$INDB
INDEPENDENT BANK CORP Stock $indb

$indb Overview Financials Valuation SEC Filings Company Website

2021 Q4 Form 10-K Financial Statement

#000077690122000048 Filed on February 28, 2022

Income Statement

Concept	2021 Q4	2021	2020 Q4
Revenue		$415.3M	$96.81M
YoY Change		3.28%	-14.86%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$8.200M	$12.50M	$6.200M
YoY Change	32.26%	-2.34%	12.73%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense		$13.72M	$5.362M
YoY Change		-60.06%	-60.89%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	-$1.100M	$156.7M	$45.20M
YoY Change	-102.43%	2.51%	-26.86%
Income Tax	-$2.800M	$35.68M	$15.40M
% Of Pretax Income		22.78%	34.07%
Net Earnings	$1.700M	$121.0M	$34.64M
YoY Change	-95.09%	-0.14%	-27.04%
Net Earnings / Revenue		29.14%	35.78%
Basic Earnings Per Share		$3.47	$1.05
Diluted Earnings Per Share	$42.08K	$3.47	$1.05
COMMON SHARES
Basic Shares Outstanding	33.05M shares	34.87M shares	32.96M shares
Diluted Shares Outstanding		34.89M shares	32.99M shares

Balance Sheet

Concept	2021 Q4	2021	2020 Q4
SHORT-TERM ASSETS
Cash & Short-Term Investments	$4.906B		$2.459B
YoY Change	99.5%		83.28%
Cash & Equivalents	$2.241B		$1.297B
Short-Term Investments	$2.665B		$1.162B
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$195.6M	$256.0M	$116.4M
YoY Change	68.04%	54.22%	-5.89%
Goodwill	$985.1M		$506.2M
YoY Change	94.6%		0.0%
Intangibles	$32.77M		$23.11M
YoY Change	41.83%		-21.1%
Long-Term Investments
YoY Change
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$20.42B	$20.42B	$13.20B
YoY Change	54.67%	54.67%	15.88%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses		$64.00M
YoY Change		14.29%
Deferred Revenue
YoY Change
Short-Term Debt
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities		$64.00M
YoY Change		14.29%
LONG-TERM LIABILITIES
Long-Term Debt	$126.7M	$127.0M	$145.3M
YoY Change	-12.81%	-12.41%	-22.44%
Other Long-Term Liabilities	$336.0M	$272.0M	$327.0M
YoY Change	2.75%	0.37%	83.71%
Total Long-Term Liabilities	$126.7M	$399.0M	$145.3M
YoY Change	-12.81%	-4.09%	-22.44%
TOTAL LIABILITIES
Total Short-Term Liabilities		$64.00M
Total Long-Term Liabilities	$126.7M	$399.0M	$145.3M
Total Liabilities	$17.40B	$17.41B	$11.50B
YoY Change	51.33%	51.32%	18.73%
SHAREHOLDERS EQUITY
Retained Earnings	$766.7M		$716.0M
YoY Change	7.08%		9.45%
Common Stock	$472.0K		$328.0K
YoY Change	43.9%		-4.09%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$3.018B	$3.018B	$1.703B
YoY Change
Total Liabilities & Shareholders Equity	$20.42B	$20.42B	$13.20B
YoY Change	54.67%	54.67%	15.88%

Cashflow Statement

Concept	2021 Q4	2021	2020 Q4
OPERATING ACTIVITIES
Net Income	$1.700M	$121.0M	$34.64M
YoY Change	-95.09%	-0.14%	-27.04%
Depreciation, Depletion And Amortization	$8.200M	$12.50M	$6.200M
YoY Change	32.26%	-2.34%	12.73%
Cash From Operating Activities	$33.40M	$190.2M	$53.80M
YoY Change	-37.92%	194.29%	-32.16%
INVESTING ACTIVITIES
Capital Expenditures	-$9.100M	$25.20M	-$4.300M
YoY Change	111.63%	100.22%	-10.42%
Acquisitions
YoY Change
Other Investing Activities	$587.8M	-$37.90M	-$33.50M
YoY Change	-1854.63%	-92.03%	-186.12%
Cash From Investing Activities	$578.8M	-$63.14M	-$37.80M
YoY Change	-1631.22%	-87.07%	-210.85%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net		$0.00
YoY Change		-100.0%
Debt Paid & Issued, Net		$18.75M
YoY Change		-55.56%
Cash From Financing Activities	-379.3M	$817.0M	12.60M
YoY Change	-3110.32%	-47.94%	-106.93%
NET CHANGE
Cash From Operating Activities	33.40M	$190.2M	53.80M
Cash From Investing Activities	578.8M	-$63.14M	-37.80M
Cash From Financing Activities	-379.3M	$817.0M	12.60M
Net Change In Cash	232.9M	$944.0M	28.60M
YoY Change	714.34%	-17.6%	-141.87%
FREE CASH FLOW
Cash From Operating Activities	$33.40M	$190.2M	$53.80M
Capital Expenditures	-$9.100M	$25.20M	-$4.300M
Free Cash Flow	$42.50M	$165.0M	$58.10M
YoY Change	-26.85%	217.04%	-30.92%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2021	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2021	dei	Entity Registrant Name EntityRegistrantName	Independent Bank Corp
CY2021	dei	Entity Central Index Key EntityCentralIndexKey	0000776901
CY2021	dei	Amendment Flag AmendmentFlag	false
CY2021	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
CY2021	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2021	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2021Q2	dei	Entity Public Float EntityPublicFloat	2464573184	USD
CY2022Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	47399980	shares
CY2021	dei	Document Type DocumentType	10-K
CY2021	dei	Document Annual Report DocumentAnnualReport	true
CY2021	dei	Document Period End Date DocumentPeriodEndDate	2021-12-31
CY2021	dei	Document Transition Report DocumentTransitionReport	false
CY2021	dei	Entity File Number EntityFileNumber	1-9047
CY2021	dei	Entity Registrant Name EntityRegistrantName	Independent Bank Corp
CY2021	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	MA
CY2021	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	04-2870273
CY2021	dei	Entity Address Address Line1 EntityAddressAddressLine1	2036 Washington Street,
CY2021	dei	Entity Address City Or Town EntityAddressCityOrTown	Hanover,
CY2021	dei	Entity Address State Or Province EntityAddressStateOrProvince	MA
CY2021	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	02339
CY2021	dei	City Area Code CityAreaCode	(781)
CY2021	dei	Local Phone Number LocalPhoneNumber	878-6100
CY2021	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2021	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2021	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2021	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2021	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2021	dei	Entity Small Business EntitySmallBusiness	false
CY2021	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2021	dei	Icfr Auditor Attestation Flag IcfrAuditorAttestationFlag	true
CY2021	dei	Entity Shell Company EntityShellCompany	false
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CY2021	dei	Document Period End Date DocumentPeriodEndDate	2021-12-31
CY2021	dei	Auditor Name AuditorName	Ernst & Young LLP
CY2021	dei	Auditor Location AuditorLocation	Boston, Massachusetts
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CY2021	indb	Gain Realized On Life Insurance Policies GainRealizedOnLifeInsurancePolicies	258000	USD
CY2020	indb	Gain Realized On Life Insurance Policies GainRealizedOnLifeInsurancePolicies	1044000	USD
CY2019	indb	Gain Realized On Life Insurance Policies GainRealizedOnLifeInsurancePolicies	434000	USD
CY2021	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	3257000	USD
CY2020	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	10058000	USD
CY2019	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	6478000	USD
CY2021	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	17584000	USD
CY2020	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	15641000	USD
CY2019	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	21004000	USD
CY2021	us-gaap	Noninterest Income NoninterestIncome	105850000	USD
CY2020	us-gaap	Noninterest Income NoninterestIncome	111440000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	115294000	USD
CY2021	us-gaap	Labor And Related Expense LaborAndRelatedExpense	172586000	USD
CY2020	us-gaap	Labor And Related Expense LaborAndRelatedExpense	152460000	USD
CY2019	us-gaap	Labor And Related Expense LaborAndRelatedExpense	149165000	USD
CY2021	us-gaap	Occupancy Net OccupancyNet	36265000	USD
CY2020	us-gaap	Occupancy Net OccupancyNet	37050000	USD
CY2019	us-gaap	Occupancy Net OccupancyNet	33207000	USD
CY2021	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	6899000	USD
CY2020	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	6265000	USD
CY2019	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	6516000	USD
CY2021	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	3980000	USD
CY2020	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	2522000	USD
CY2019	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1394000	USD
CY2021	us-gaap	Advertising Expense AdvertisingExpense	4085000	USD
CY2020	us-gaap	Advertising Expense AdvertisingExpense	4258000	USD
CY2019	us-gaap	Advertising Expense AdvertisingExpense	5444000	USD
CY2021	us-gaap	Professional Fees ProfessionalFees	8271000	USD
CY2020	us-gaap	Professional Fees ProfessionalFees	5987000	USD
CY2019	us-gaap	Professional Fees ProfessionalFees	5448000	USD
CY2021	us-gaap	Cost Of Goods And Services Sold Amortization CostOfGoodsAndServicesSoldAmortization	5715000	USD
CY2020	us-gaap	Cost Of Goods And Services Sold Amortization CostOfGoodsAndServicesSoldAmortization	6135000	USD
CY2019	us-gaap	Cost Of Goods And Services Sold Amortization CostOfGoodsAndServicesSoldAmortization	6379000	USD
CY2021	indb	Debit Card Expense DebitCardExpense	5144000	USD
CY2020	indb	Debit Card Expense DebitCardExpense	4374000	USD
CY2019	indb	Debit Card Expense DebitCardExpense	4220000	USD
CY2021	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	0	USD
CY2020	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	4163000	USD
CY2019	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	0	USD
CY2021	us-gaap	Gain Loss On Sale Of Other Investments GainLossOnSaleOfOtherInvestments	0	USD
CY2020	us-gaap	Gain Loss On Sale Of Other Investments GainLossOnSaleOfOtherInvestments	1033000	USD
CY2019	us-gaap	Gain Loss On Sale Of Other Investments GainLossOnSaleOfOtherInvestments	0	USD
CY2021	indb	Availablefor Sale Securities Fixed Income Gross Realized Losses AvailableforSaleSecuritiesFixedIncomeGrossRealizedLosses	0	USD
CY2020	indb	Availablefor Sale Securities Fixed Income Gross Realized Losses AvailableforSaleSecuritiesFixedIncomeGrossRealizedLosses	0	USD
CY2019	indb	Availablefor Sale Securities Fixed Income Gross Realized Losses AvailableforSaleSecuritiesFixedIncomeGrossRealizedLosses	1462000	USD
CY2021	us-gaap	Loss On Contract Termination LossOnContractTermination	0	USD
CY2020	us-gaap	Loss On Contract Termination LossOnContractTermination	684000	USD
CY2019	us-gaap	Loss On Contract Termination LossOnContractTermination	0	USD
CY2021	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	40840000	USD
CY2019	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	26433000	USD
CY2021	indb	Software Maintenance SoftwareMaintenance	8149000	USD
CY2020	indb	Software Maintenance SoftwareMaintenance	7264000	USD
CY2019	indb	Software Maintenance SoftwareMaintenance	5511000	USD
CY2021	us-gaap	Other Noninterest Expense OtherNoninterestExpense	40595000	USD
CY2020	us-gaap	Other Noninterest Expense OtherNoninterestExpense	41637000	USD
CY2019	us-gaap	Other Noninterest Expense OtherNoninterestExpense	39142000	USD
CY2021	us-gaap	Noninterest Expense NoninterestExpense	332529000	USD
CY2020	us-gaap	Noninterest Expense NoninterestExpense	273832000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	284321000	USD
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	156675000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	152836000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	218108000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	35683000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	31669000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	52933000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	120992000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	121167000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	165175000	USD
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.47
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.64
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	5.03
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.47
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.64
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	5.03
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	34872034	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	33259643	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	32810433	shares
CY2021	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	16484	shares
CY2020	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	25646	shares
CY2019	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	45801	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	34888518	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	33285289	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	32856234	shares
CY2021	us-gaap	Net Income Loss NetIncomeLoss	120992000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	121167000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	165175000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-22922000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	8857000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	10345000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	-19139000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	16797000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	10331000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-3549000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	3128000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	1334000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-38512000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	22526000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	19342000	USD
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	82480000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Effect Of Change In Method FinancingReceivableAllowanceForCreditLossesEffectOfChangeInMethod	-1100000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	143693000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	184517000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	1073490000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	165175000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	19342000	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	57729000	USD
CY2019	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	499693000	USD
CY2019	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	281000	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	4403000	USD
CY2019	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	-1463000	USD
CY2019	us-gaap	Stock Issued During Period Value Other StockIssuedDuringPeriodValueOther	4951000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	1708143000	USD
CY2020	us-gaap	Prior Period Reclassification Adjustment PriorPeriodReclassificationAdjustment	1553000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	121167000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	22526000	USD
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	60878000	USD
CY2020	indb	Financing Receivable Allowancefor Credit Losses Effectof Changein Methodnetoftax. FinancingReceivableAllowanceforCreditLossesEffectofChangeinMethodnetoftax.	817000	USD
CY2020	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	197000	USD
CY2020	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	4123000	USD
CY2020	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	-1187000	USD
CY2020	us-gaap	Stock Issued During Period Value Other StockIssuedDuringPeriodValueOther	2132000	USD
CY2020	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	95091000	USD
CY2020	us-gaap	Increase Decrease In Deferred Compensation IncreaseDecreaseInDeferredCompensation	0	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	1702685000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	120992000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-38512000	USD
CY2021	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	70300000	USD
CY2021	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	1298558000	USD
CY2021	indb	Stock Repurchased During Period Valueasaresultof Stock Options Exercised StockRepurchasedDuringPeriodValueasaresultofStockOptionsExercised	57000	USD
CY2021	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	4309000	USD
CY2021	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	-1249000	USD
CY2021	us-gaap	Stock Issued During Period Value Other StockIssuedDuringPeriodValueOther	2023000	USD
CY2021	us-gaap	Increase Decrease In Deferred Compensation IncreaseDecreaseInDeferredCompensation	0	USD
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	3018449000	USD
CY2020	us-gaap	Off Balance Sheet Credit Loss Liability Change In Method Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityChangeInMethodCreditLossExpenseReversal	-1000000	USD
CY2020	indb	Off Balance Sheet Credit Loss Liability Changein Method Credit Loss Expense Reversalnetoftax. OffBalanceSheetCreditLossLiabilityChangeinMethodCreditLossExpenseReversalnetoftax.	736000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	120992000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	121167000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	165175000	USD
CY2021	us-gaap	Depreciation And Amortization DepreciationAndAmortization	32824000	USD
CY2020	us-gaap	Depreciation And Amortization DepreciationAndAmortization	27262000	USD
CY2019	us-gaap	Depreciation And Amortization DepreciationAndAmortization	19439000	USD
CY2021	indb	Change In Unamortized Net Loan Costs And Premiums ChangeInUnamortizedNetLoanCostsAndPremiums	24785000	USD
CY2020	indb	Change In Unamortized Net Loan Costs And Premiums ChangeInUnamortizedNetLoanCostsAndPremiums	7126000	USD
CY2019	indb	Change In Unamortized Net Loan Costs And Premiums ChangeInUnamortizedNetLoanCostsAndPremiums	-2692000	USD
CY2021	indb	Accretion Of Acquired Loans AccretionOfAcquiredLoans	6882000	USD
CY2020	indb	Accretion Of Acquired Loans AccretionOfAcquiredLoans	6286000	USD
CY2019	indb	Accretion Of Acquired Loans AccretionOfAcquiredLoans	12778000	USD
CY2021	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	18205000	USD
CY2020	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	52500000	USD
CY2019	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	6000000	USD
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	3090000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-17506000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	10594000	USD
CY2021	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	554000	USD
CY2020	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	528000	USD
CY2019	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	1566000	USD
CY2019	us-gaap	Gain Loss On Investments GainLossOnInvestments	-1462000	USD
CY2021	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-139000	USD
CY2020	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-372000	USD
CY2019	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	474000	USD
CY2021	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	0	USD
CY2020	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	4163000	USD
CY2019	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	0	USD
CY2021	us-gaap	Loss On Derivative Instruments Pretax LossOnDerivativeInstrumentsPretax	0	USD
CY2020	us-gaap	Loss On Derivative Instruments Pretax LossOnDerivativeInstrumentsPretax	684000	USD
CY2019	us-gaap	Loss On Derivative Instruments Pretax LossOnDerivativeInstrumentsPretax	0	USD
CY2021	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	0	USD
CY2020	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	0	USD
CY2019	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-401000	USD
CY2021	us-gaap	Sale And Leaseback Transaction Gain Loss Net SaleAndLeasebackTransactionGainLossNet	578000	USD
CY2020	us-gaap	Sale And Leaseback Transaction Gain Loss Net SaleAndLeasebackTransactionGainLossNet	578000	USD
CY2019	us-gaap	Sale And Leaseback Transaction Gain Loss Net SaleAndLeasebackTransactionGainLossNet	578000	USD
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	4309000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	4123000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	4403000	USD
CY2021	us-gaap	Life Insurance Corporate Or Bank Owned Change In Value LifeInsuranceCorporateOrBankOwnedChangeInValue	6431000	USD
CY2020	us-gaap	Life Insurance Corporate Or Bank Owned Change In Value LifeInsuranceCorporateOrBankOwnedChangeInValue	5362000	USD
CY2019	us-gaap	Life Insurance Corporate Or Bank Owned Change In Value LifeInsuranceCorporateOrBankOwnedChangeInValue	5013000	USD
CY2021	indb	Gain Realized On Life Insurance Policies GainRealizedOnLifeInsurancePolicies	258000	USD
CY2020	indb	Gain Realized On Life Insurance Policies GainRealizedOnLifeInsurancePolicies	1044000	USD
CY2019	indb	Gain Realized On Life Insurance Policies GainRealizedOnLifeInsurancePolicies	434000	USD
CY2021	us-gaap	Operating Lease Payments OperatingLeasePayments	17456000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	11936000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	10669000	USD
CY2021	indb	Change In Fair Value On Loans Held For Sale ChangeInFairValueOnLoansHeldForSale	-1679000	USD
CY2020	indb	Change In Fair Value On Loans Held For Sale ChangeInFairValueOnLoansHeldForSale	1296000	USD
CY2019	indb	Change In Fair Value On Loans Held For Sale ChangeInFairValueOnLoansHeldForSale	822000	USD
CY2021	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	882000	USD
CY2020	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	659000	USD
CY2019	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	675000	USD
CY2021	us-gaap	Increase Decrease In Loans Held For Sale IncreaseDecreaseInLoansHeldForSale	-31746000	USD
CY2020	us-gaap	Increase Decrease In Loans Held For Sale IncreaseDecreaseInLoansHeldForSale	23501000	USD
CY2019	us-gaap	Increase Decrease In Loans Held For Sale IncreaseDecreaseInLoansHeldForSale	-59932000	USD
CY2021	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-93565000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	145953000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	39850000	USD
CY2021	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-58503000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	76140000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	19283000	USD
CY2021	us-gaap	Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities	69228000	USD
CY2020	us-gaap	Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities	-56531000	USD
CY2019	us-gaap	Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities	51347000	USD
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	190220000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	64636000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	216522000	USD
CY2021	us-gaap	Proceeds From Sale Of Trading Securities Heldforinvestment ProceedsFromSaleOfTradingSecuritiesHeldforinvestment	1164000	USD
CY2020	us-gaap	Proceeds From Sale Of Trading Securities Heldforinvestment ProceedsFromSaleOfTradingSecuritiesHeldforinvestment	0	USD
CY2019	us-gaap	Proceeds From Sale Of Trading Securities Heldforinvestment ProceedsFromSaleOfTradingSecuritiesHeldforinvestment	1461000	USD
CY2021	us-gaap	Increase Decrease In Equity Securities Fv Ni IncreaseDecreaseInEquitySecuritiesFvNi	2171000	USD
CY2020	us-gaap	Increase Decrease In Equity Securities Fv Ni IncreaseDecreaseInEquitySecuritiesFvNi	803000	USD
CY2019	us-gaap	Increase Decrease In Equity Securities Fv Ni IncreaseDecreaseInEquitySecuritiesFvNi	711000	USD
CY2021	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	45863000	USD
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	95981000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	108893000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	51104000	USD
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	1284867000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	84156000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	68677000	USD
CY2021	us-gaap	Proceeds From Maturities Repayments And Calls Of Trading Securities Heldforinvestment ProceedsFromMaturitiesRepaymentsAndCallsOfTradingSecuritiesHeldforinvestment	263106000	USD
CY2020	us-gaap	Proceeds From Maturities Repayments And Calls Of Trading Securities Heldforinvestment ProceedsFromMaturitiesRepaymentsAndCallsOfTradingSecuritiesHeldforinvestment	261705000	USD
CY2019	us-gaap	Proceeds From Maturities Repayments And Calls Of Trading Securities Heldforinvestment ProceedsFromMaturitiesRepaymentsAndCallsOfTradingSecuritiesHeldforinvestment	126991000	USD
CY2021	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	606543000	USD
CY2020	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	244718000	USD
CY2019	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	59967000	USD
CY2021	us-gaap	Payments For Proceeds From Federal Home Loan Bank Stock PaymentsForProceedsFromFederalHomeLoanBankStock	-25027000	USD
CY2020	us-gaap	Payments For Proceeds From Federal Home Loan Bank Stock PaymentsForProceedsFromFederalHomeLoanBankStock	-4174000	USD
CY2019	us-gaap	Payments For Proceeds From Federal Home Loan Bank Stock PaymentsForProceedsFromFederalHomeLoanBankStock	-18896000	USD
CY2021	indb	Investmentin Low Income Housing Projects InvestmentinLowIncomeHousingProjects	-22496000	USD
CY2020	indb	Investmentin Low Income Housing Projects InvestmentinLowIncomeHousingProjects	-17858000	USD
CY2019	indb	Investmentin Low Income Housing Projects InvestmentinLowIncomeHousingProjects	-10052000	USD
CY2021	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	40164000	USD
CY2020	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	164000	USD
CY2019	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	163000	USD
CY2021	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	576000	USD
CY2020	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	3417000	USD
CY2019	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	3162000	USD
CY2021	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	-744981000	USD
CY2020	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	511526000	USD
CY2019	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	-27816000	USD
CY2021	us-gaap	Cash Acquired In Excess Of Payments To Acquire Business CashAcquiredInExcessOfPaymentsToAcquireBusiness	787301000	USD
CY2020	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
CY2019	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	105264000	USD
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	25200000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	12586000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	16583000	USD
CY2021	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	169000	USD
CY2020	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	6095000	USD
CY2019	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	3796000	USD
CY2021	indb	Payments On Early Termination Of Hedging Relationship PaymentsOnEarlyTerminationOfHedgingRelationship	0	USD
CY2020	indb	Payments On Early Termination Of Hedging Relationship PaymentsOnEarlyTerminationOfHedgingRelationship	684000	USD
CY2019	indb	Payments On Early Termination Of Hedging Relationship PaymentsOnEarlyTerminationOfHedgingRelationship	0	USD
CY2021	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	0	USD
CY2020	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	0	USD
CY2019	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	2488000	USD
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-63136000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-488211000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	20160000	USD
CY2021	us-gaap	Increase Decrease In Time Deposits IncreaseDecreaseInTimeDeposits	-235577000	USD
CY2020	us-gaap	Increase Decrease In Time Deposits IncreaseDecreaseInTimeDeposits	-444276000	USD
CY2019	us-gaap	Increase Decrease In Time Deposits IncreaseDecreaseInTimeDeposits	-45272000	USD
CY2021	us-gaap	Increase Decrease In Other Deposits IncreaseDecreaseInOtherDeposits	1719398000	USD
CY2020	us-gaap	Increase Decrease In Other Deposits IncreaseDecreaseInOtherDeposits	2290489000	USD
CY2019	us-gaap	Increase Decrease In Other Deposits IncreaseDecreaseInOtherDeposits	-160637000	USD
CY2021	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	0	USD
CY2020	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	-45000000	USD
CY2019	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	-132046000	USD
CY2021	indb	Increase Decrease In Federal Home Loan Bank Advances Long Term IncreaseDecreaseInFederalHomeLoanBankAdvancesLongTerm	-586088000	USD
CY2020	indb	Increase Decrease In Federal Home Loan Bank Advances Long Term IncreaseDecreaseInFederalHomeLoanBankAdvancesLongTerm	-35000000	USD
CY2019	indb	Increase Decrease In Federal Home Loan Bank Advances Long Term IncreaseDecreaseInFederalHomeLoanBankAdvancesLongTerm	-25000000	USD
CY2021	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	0	USD
CY2020	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	0	USD
CY2019	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	49980000	USD
CY2021	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	0	USD
CY2020	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	0	USD
CY2019	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	49980000	USD
CY2021	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	18750000	USD
CY2020	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	42187000	USD
CY2019	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	74867000	USD
CY2021	indb	Repayments Of Junior Subordinated Debt RepaymentsOfJuniorSubordinatedDebt	0	USD
CY2020	indb	Repayments Of Junior Subordinated Debt RepaymentsOfJuniorSubordinatedDebt	0	USD
CY2019	indb	Repayments Of Junior Subordinated Debt RepaymentsOfJuniorSubordinatedDebt	13329000	USD
CY2021	us-gaap	Proceeds From Issuance Of Subordinated Long Term Debt ProceedsFromIssuanceOfSubordinatedLongTermDebt	0	USD
CY2020	us-gaap	Proceeds From Issuance Of Subordinated Long Term Debt ProceedsFromIssuanceOfSubordinatedLongTermDebt	0	USD
CY2019	us-gaap	Proceeds From Issuance Of Subordinated Long Term Debt ProceedsFromIssuanceOfSubordinatedLongTermDebt	49526000	USD
CY2021	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	USD
CY2020	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	USD
CY2019	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	34767000	USD
CY2021	indb	Net Payments From Exercise Of Stock Options NetPaymentsFromExerciseOfStockOptions	57000	USD
CY2020	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	197000	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	281000	USD
CY2021	indb	Issuance Of Restricted Stock Awards Netof Issuance Cost IssuanceOfRestrictedStockAwardsNetofIssuanceCost	1249000	USD
CY2020	indb	Issuance Of Restricted Stock Awards Netof Issuance Cost IssuanceOfRestrictedStockAwardsNetofIssuanceCost	1187000	USD
CY2019	indb	Issuance Of Restricted Stock Awards Netof Issuance Cost IssuanceOfRestrictedStockAwardsNetofIssuanceCost	1463000	USD
CY2021	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	2023000	USD
CY2020	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	2132000	USD
CY2019	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	4951000	USD
CY2021	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	USD
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	95091000	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	USD
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	62736000	USD
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	60840000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	53274000	USD
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	816964000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	1569237000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-336163000	USD
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	944048000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	1145662000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-99481000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents And Federal Funds Sold CashCashEquivalentsAndFederalFundsSold	1296636000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents And Federal Funds Sold CashCashEquivalentsAndFederalFundsSold	150974000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents And Federal Funds Sold CashCashEquivalentsAndFederalFundsSold	250455000	USD
CY2021Q4	us-gaap	Cash Cash Equivalents And Federal Funds Sold CashCashEquivalentsAndFederalFundsSold	2240684000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents And Federal Funds Sold CashCashEquivalentsAndFederalFundsSold	1296636000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents And Federal Funds Sold CashCashEquivalentsAndFederalFundsSold	150974000	USD
CY2021	us-gaap	Interest Paid Net InterestPaidNet	14004000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	36739000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	49704000	USD
CY2021	us-gaap	Income Taxes Paid IncomeTaxesPaid	23353000	USD
CY2020	us-gaap	Income Taxes Paid IncomeTaxesPaid	48240000	USD
CY2019	us-gaap	Income Taxes Paid IncomeTaxesPaid	39575000	USD
CY2021	indb	Capitalcommitmentrelatingto Low Income Housing Projectinvestmentsnoncash CapitalcommitmentrelatingtoLowIncomeHousingProjectinvestmentsnoncash	33691000	USD
CY2020	indb	Capitalcommitmentrelatingto Low Income Housing Projectinvestmentsnoncash CapitalcommitmentrelatingtoLowIncomeHousingProjectinvestmentsnoncash	32477000	USD
CY2019	indb	Capitalcommitmentrelatingto Low Income Housing Projectinvestmentsnoncash CapitalcommitmentrelatingtoLowIncomeHousingProjectinvestmentsnoncash	36543000	USD
CY2019Q1	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	32777000	USD
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	7768000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	8646000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	14951000	USD
CY2021	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	1298558000	USD
CY2020	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	0	USD
CY2019	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	499693000	USD
CY2021Q4	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Assets BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets	5574209000	USD
CY2020Q4	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Assets BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets	0	USD
CY2019Q4	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Assets BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets	2711067000	USD
CY2021Q4	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Liabilities BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities	5062952000	USD
CY2020Q4	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Liabilities BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities	0	USD
CY2019Q4	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Liabilities BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities	2106110000	USD
CY2019Q1	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	32800000	USD
CY2019Q1	us-gaap	Operating Lease Liability OperatingLeaseLiability	34100000	USD
CY2019Q1	us-gaap	Deferred Rent Credit DeferredRentCredit	1300000	USD
CY2021	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	<div style="margin-top:14pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Reclassification</span></div><div style="margin-top:5pt;text-align:justify;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Certain previously reported amounts have been reclassified to conform to the current year’s presentation.</span></div>
CY2021	us-gaap	Use Of Estimates UseOfEstimates	<div style="margin-top:14pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Use of Estimates</span></div><div style="margin-top:5pt;text-align:justify;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America ("GAAP") requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could vary from these estimates. Material estimates that are particularly susceptible to significant changes in the near-term relate to the determination of the allowance for expected credit losses on loans held for investment, income taxes, and valuation and allowance for expected credit losses on investment securities.</span></div>
CY2021	us-gaap	Concentration Risk Credit Risk ConcentrationRiskCreditRisk	<div style="margin-top:14pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Significant Concentrations of Credit Risk</span></div><div style="margin-top:5pt;text-align:justify;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The vast majority of the Bank’s lending activities are conducted in Massachusetts and Rhode Island. The Bank originates commercial and industrial loans, commercial and residential real estate loans, including construction loans, small business loans, home equity loans, and other consumer loans for its portfolio. The Bank considers a concentration of credit to a particular industry to exist when the aggregate credit exposure which includes direct, indirect or contingent obligations to a borrower, an affiliated group of borrowers or a nonaffiliated group of borrowers engaged in one industry, exceeds 25% of the Bank’s tier one capital.</span></div><div style="margin-top:9pt;text-align:justify;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Loans originated by the Bank to lessors of nonresidential buildings represented 23.6% and 17.1% of the total loan portfolio at December 31, 2021 and 2020, respectively. Within this concentration category, the Company believes it is well diversified among collateral property types and tenant industries.</span></div>
CY2021	indb	Days To Be Termed As Non Accrual Loans DaysToBeTermedAsNonAccrualLoans	P90D
CY2021	indb	Days To Be Termed As Non Accrual Loans DaysToBeTermedAsNonAccrualLoans	P90D
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Policy For Uncollectible Amounts FinancingReceivableAllowanceForCreditLossesPolicyForUncollectibleAmounts	<div style="margin-top:14pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Allowance for Credit Losses - Loans Held for Investment</span></div><div style="margin-top:5pt;text-align:justify;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The allowance for credit losses is established based upon the Company's current estimate of expected lifetime credit losses on loans measured at amortized cost, also referred to as the "CECL methodology". Credit losses are charged against the allowance when management's assessments confirm that the Company will not collect the full amortized cost basis of a loan. Subsequent recoveries, if any, are credited to the allowance.</span></div><div style="margin-top:9pt;text-align:justify;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Under the CECL methodology, the Company estimates credit losses for financial assets on a collective basis for loans sharing similar risk characteristics using a quantitative model combined with an assessment of certain qualitative factors designed to address forecast risk and model risk inherent in the quantitative model output. The quantitative model utilizes a factor based approach to estimate expected credit losses using Probability of Default ("PD"), Loss Given Default ("LGD") and Exposure at Default ("EAD"), which are derived from internal historical default and loss experience. The model estimates expected credit losses using loan level data over the estimated life of the exposure, considering the effect of prepayments. Economic forecasts are incorporated into the estimate over a reasonable and supportable forecast period, beyond which is a reversion to the Company's historical long-run average. Management has determined a reasonable and supportable period of 12 months, and a straight line reversion period of 6 months, to be appropriate for purposes of estimating expected credit losses. The qualitative risk factors impacting the expected risk of loss within the portfolio include the following:</span></div><div style="margin-top:5pt;padding-left:45pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Lending policies and procedures</span></div><div style="margin-top:5pt;padding-left:45pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Economic and business conditions</span></div><div style="margin-top:5pt;padding-left:45pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Nature and volume of loans</span></div><div style="margin-top:5pt;padding-left:45pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Changes in management</span></div><div style="margin-top:5pt;padding-left:45pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Changes in credit quality</span></div><div style="margin-top:5pt;padding-left:45pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Changes in loan review system</span></div><div style="margin-top:5pt;padding-left:45pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Changes to underlying collateral values</span></div><div style="margin-top:5pt;padding-left:45pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Concentrations of credit risk</span></div><div style="margin-top:5pt;padding-left:45pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Model imprecision</span></div><div style="margin-top:5pt;padding-left:45pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Other external factors</span></div><div style="margin-top:9pt;text-align:justify;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Loans that do not share similar risk characteristics with any pools of assets are subject to individual evaluation and are removed from the collectively assessed pools to avoid double counting. For the loans that are individually evaluated, the Company uses either a discounted cash flow (“DCF”) approach or a fair value of collateral approach. The latter approach is used for loans deemed to be collateral dependent or when foreclosure is probable. </span></div><div style="margin-top:9pt;text-align:justify;text-indent:27pt"><span><br/></span></div><div style="margin-top:9pt;text-align:justify;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Accrued interest receivable amounts are excluded from balances of loans held at amortized cost and are included within other assets on the consolidated balance sheets. Management has elected not to measure an allowance for credit losses on these amounts as the Company employs a timely write-off policy. Consistent with the Company's policy for nonaccrual loans, accrued interest receivable is typically written off when loans reach 90 days past due and are placed on nonaccrual status.</span></div>In the ordinary course of business, the Company enters into commitments to extend credit, commercial letters of credit, and standby letters of credit. Such financial instruments are recorded in the financial statements when they become payable. The credit risk associated with these commitments is evaluated in a manner similar to the allowance for credit losses. The reserve for unfunded lending commitments is included in other liabilities on the Consolidated Balance Sheets.
CY2021	indb	Days To Be Termed As Non Accrual Loans DaysToBeTermedAsNonAccrualLoans	P90D
CY2021Q4	us-gaap	Trading Securities Debt TradingSecuritiesDebt	3700000	USD
CY2020Q4	us-gaap	Trading Securities Debt TradingSecuritiesDebt	2800000	USD
CY2021Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	23200000	USD
CY2020Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	22100000	USD
CY2021	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	554000	USD
CY2020	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	528000	USD
CY2019	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	1566000	USD
CY2021	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	192000	USD
CY2020	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	14000	USD
CY2019	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	18000	USD
CY2021	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	362000	USD
CY2020	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	514000	USD
CY2019	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	1548000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	1583736000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	8808000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	21396000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	1571148000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	395453000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	17869000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	462000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	412860000	USD
CY2020	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Period Increase Decrease DebtSecuritiesAvailableForSaleAllowanceForCreditLossPeriodIncreaseDecrease	0	USD
CY2021	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Period Increase Decrease DebtSecuritiesAvailableForSaleAllowanceForCreditLossPeriodIncreaseDecrease	0	USD
CY2021	us-gaap	Debt Securities Available For Sale Accrued Interest Writeoff DebtSecuritiesAvailableForSaleAccruedInterestWriteoff	0	USD
CY2020	us-gaap	Debt Securities Available For Sale Accrued Interest Writeoff DebtSecuritiesAvailableForSaleAccruedInterestWriteoff	0	USD
CY2021Q4	indb	Debt Securities Availableforsale Pastdue DebtSecuritiesAvailableforsalePastdue	0	USD
CY2020Q4	indb	Debt Securities Availableforsale Pastdue DebtSecuritiesAvailableforsalePastdue	0	USD
CY2020	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	0	USD
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	0	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	37	holding
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	1210544000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	21197000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	1000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	199000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	1211544000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	21396000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	7	holding
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	24248000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	89000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	1056000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	373000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	25304000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	462000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	12474000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	15159000	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	0	USD
CY2021Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	1064133000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	28007000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	342000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	0	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	752177000	USD
CY2020	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Period Increase Decrease DebtSecuritiesHeldToMaturityAllowanceForCreditLossPeriodIncreaseDecrease	0	USD
CY2021	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Period Increase Decrease DebtSecuritiesHeldToMaturityAllowanceForCreditLossPeriodIncreaseDecrease	0	USD
CY2020	us-gaap	Debt Securities Held To Maturity Accrued Interest Writeoff DebtSecuritiesHeldToMaturityAccruedInterestWriteoff	0	USD
CY2021	us-gaap	Debt Securities Held To Maturity Accrued Interest Writeoff DebtSecuritiesHeldToMaturityAccruedInterestWriteoff	0	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity90 Days Or More Past Due Still Accruing DebtSecuritiesHeldToMaturity90DaysOrMorePastDueStillAccruing	0	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity90 Days Or More Past Due Still Accruing DebtSecuritiesHeldToMaturity90DaysOrMorePastDueStillAccruing	0	USD
CY2021	us-gaap	Held To Maturity Securities Sold Security Realized Gain Loss HeldToMaturitySecuritiesSoldSecurityRealizedGainLoss	0	USD
CY2020	us-gaap	Held To Maturity Securities Sold Security Realized Gain Loss HeldToMaturitySecuritiesSoldSecurityRealizedGainLoss	0	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	1583736000	USD
CY2021Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	1066818000	USD
CY2021Q4	indb	Available For Saleand Held To Maturity Debt Securities Maturities Within One Year Amortized Cost AvailableForSaleandHeldToMaturityDebtSecuritiesMaturitiesWithinOneYearAmortizedCost	26414000	USD
CY2021Q4	indb	Available For Saleand Held To Maturity Debt Securities Maturities Within One Year Fair Value AvailableForSaleandHeldToMaturityDebtSecuritiesMaturitiesWithinOneYearFairValue	26579000	USD
CY2021Q4	indb	Available For Saleand Held To Maturity Debt Securities Maturities After One Through Five Years Amortized Cost AvailableForSaleandHeldToMaturityDebtSecuritiesMaturitiesAfterOneThroughFiveYearsAmortizedCost	818467000	USD
CY2021Q4	indb	Available For Saleand Held To Maturity Debt Securities Maturities After One Through Five Years Fair Value AvailableForSaleandHeldToMaturityDebtSecuritiesMaturitiesAfterOneThroughFiveYearsFairValue	809993000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	3729000	USD
CY2021Q4	indb	Available For Saleand Held To Maturity Debt Securities Maturities After Five Through Ten Years Amortized Cost AvailableForSaleandHeldToMaturityDebtSecuritiesMaturitiesAfterFiveThroughTenYearsAmortizedCost	927300000	USD
CY2021Q4	indb	Available For Saleand Held To Maturity Debt Securities Maturities After Five Through Ten Years Fair Value AvailableForSaleandHeldToMaturityDebtSecuritiesMaturitiesAfterFiveThroughTenYearsFairValue	917542000	USD
CY2021Q4	indb	Available For Saleand Held To Maturity Debt Securities Maturities After Ten Years Amortized Cost AvailableForSaleandHeldToMaturityDebtSecuritiesMaturitiesAfterTenYearsAmortizedCost	878373000	USD
CY2021Q4	indb	Available For Saleand Held To Maturity Debt Securities Maturities After Ten Years Fair Value AvailableForSaleandHeldToMaturityDebtSecuritiesMaturitiesAfterTenYearsFairValue	881167000	USD
CY2021Q4	indb	Available For Saleand Held To Maturity Debt Securities Amortized Cost AvailableForSaleandHeldToMaturityDebtSecuritiesAmortizedCost	2650554000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale And Held To Maturity DebtSecuritiesAvailableForSaleAndHeldToMaturity	2635281000	USD
CY2021Q4	indb	Callable Securities In Investment Portfolio CallableSecuritiesInInvestmentPortfolio	3200000	USD
CY2021Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	740600000	USD
CY2020Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	419600000	USD
CY2021Q4	indb	Investmentsinobligationsofindividualstatescountiesormunicipalitieswhichexceed10ofequity Investmentsinobligationsofindividualstatescountiesormunicipalitieswhichexceed10ofequity	0	USD
CY2020Q4	indb	Investmentsinobligationsofindividualstatescountiesormunicipalitieswhichexceed10ofequity Investmentsinobligationsofindividualstatescountiesormunicipalitieswhichexceed10ofequity	0	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	113392000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	4944000	USD
CY2021Q4	us-gaap	Financing Receivable Purchased With Credit Deterioration Allowance For Credit Loss At Acquisition Date FinancingReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate	16540000	USD
CY2021	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	18205000	USD
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	146922000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	67740000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Effect Of Change In Method FinancingReceivableAllowanceForCreditLossesEffectOfChangeInMethod	-1137000	USD
CY2020	indb	Financing Receivable Allowance For Credit Loss Purchased With Credit Deterioration FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeterioration	1157000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	8446000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	1578000	USD
CY2020	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	52500000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	113392000	USD
CY2021Q4	us-gaap	Interest Receivable InterestReceivable	43700000	USD
CY2020Q4	us-gaap	Interest Receivable InterestReceivable	36000000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Effect Of Change In Method FinancingReceivableAllowanceForCreditLossesEffectOfChangeInMethod	-1100000	USD
CY2020	indb	Financing Receivable Allowance For Credit Loss Purchased With Credit Deterioration FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeterioration	1200000	USD
CY2021Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	146900000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Period Increase Decrease FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease	-33500000	USD
CY2021	indb	Financing Receivable Allowancefor Credit Loss Period Increase Decreasebypercentage FinancingReceivableAllowanceforCreditLossPeriodIncreaseDecreasebypercentage	0.296
CY2021Q4	us-gaap	Financing Receivable Purchased With Credit Deterioration Allowance For Credit Loss At Acquisition Date FinancingReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate	16500000	USD
CY2021Q4	us-gaap	Financing Receivable Originated In Current Fiscal Year FinancingReceivableOriginatedInCurrentFiscalYear	2962947000	USD
CY2021Q4	us-gaap	Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear	2273064000	USD
CY2021Q4	us-gaap	Financing Receivable Originated Two Years Before Latest Fiscal Year FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear	1344438000	USD
CY2021Q4	us-gaap	Financing Receivable Originated Three Years Before Latest Fiscal Year FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear	1331466000	USD
CY2021Q4	us-gaap	Financing Receivable Originated Four Years Before Latest Fiscal Year FinancingReceivableOriginatedFourYearsBeforeLatestFiscalYear	1126800000	USD
CY2021Q4	us-gaap	Financing Receivable Originated Five Or More Years Before Latest Fiscal Year FinancingReceivableOriginatedFiveOrMoreYearsBeforeLatestFiscalYear	2905961000	USD
CY2021Q4	us-gaap	Financing Receivable Revolving FinancingReceivableRevolving	1636023000	USD
CY2021Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	13587286000	USD
CY2020Q4	us-gaap	Financing Receivable Originated In Current Fiscal Year FinancingReceivableOriginatedInCurrentFiscalYear	2812901000	USD
CY2020Q4	us-gaap	Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear	1341947000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Two Years Before Latest Fiscal Year FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear	896983000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Three Years Before Latest Fiscal Year FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear	857830000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Four Years Before Latest Fiscal Year FinancingReceivableOriginatedFourYearsBeforeLatestFiscalYear	698323000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Five Or More Years Before Latest Fiscal Year FinancingReceivableOriginatedFiveOrMoreYearsBeforeLatestFiscalYear	1314136000	USD
CY2020Q4	us-gaap	Financing Receivable Revolving FinancingReceivableRevolving	1447865000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	9392866000	USD
CY2021Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1500000	USD
CY2020Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1200000	USD
CY2021	indb	Days To Be Termed As Non Accrual Loans DaysToBeTermedAsNonAccrualLoans	P90D
CY2021	indb	Days To Be Termed As Non Accrual Loans DaysToBeTermedAsNonAccrualLoans	P90D
CY2021Q4	indb	Loanswithactive Deferrals LoanswithactiveDeferrals	383100000	USD
CY2020Q4	indb	Loanswithactive Deferrals LoanswithactiveDeferrals	173600000	USD
CY2021Q4	indb	Finance Receivable Nonaccrualwithallowance FinanceReceivableNonaccrualwithallowance	27199000	USD
CY2021Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	621000	USD
CY2021Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	27820000	USD
CY2020Q4	indb	Finance Receivable Nonaccrualwithallowance FinanceReceivableNonaccrualwithallowance	31332000	USD
CY2020Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	35528000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	66860000	USD
CY2021Q4	indb	Tdrs Recorded Investment On Nonaccrual Status TdrsRecordedInvestmentOnNonaccrualStatus	2000000	USD
CY2020Q4	indb	Tdrs Recorded Investment On Nonaccrual Status TdrsRecordedInvestmentOnNonaccrualStatus	22200000	USD
CY2021Q4	indb	Foreclosedresidentialrealestatepropertyheldbythecreditor Foreclosedresidentialrealestatepropertyheldbythecreditor	0	USD
CY2020Q4	indb	Foreclosedresidentialrealestatepropertyheldbythecreditor Foreclosedresidentialrealestatepropertyheldbythecreditor	0	USD
CY2021Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	1426000	USD
CY2020Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	1750000	USD
CY2021Q4	indb	Number Of Financing Receivables Thirty To Fifty Nine Days Past Due NumberOfFinancingReceivablesThirtyToFiftyNineDaysPastDue	518	loan
CY2021Q4	indb	Number Of Financing Receivables Sixty To Eighty Nine Days Past Due NumberOfFinancingReceivablesSixtyToEightyNineDaysPastDue	60	loan
CY2021Q4	indb	Number Of Financing Receivables Equal To Greater Than Ninety Days NumberOfFinancingReceivablesEqualToGreaterThanNinetyDays	123	loan
CY2021Q4	indb	Number Of Financing Receivables Total Past Due NumberOfFinancingReceivablesTotalPastDue	701	loan
CY2021Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	13540590000	USD
CY2021Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	13587286000	USD
CY2021Q4	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	0	USD
CY2020Q4	indb	Number Of Financing Receivables Thirty To Fifty Nine Days Past Due NumberOfFinancingReceivablesThirtyToFiftyNineDaysPastDue	301	loan
CY2020Q4	indb	Number Of Financing Receivables Sixty To Eighty Nine Days Past Due NumberOfFinancingReceivablesSixtyToEightyNineDaysPastDue	25	loan
CY2020Q4	indb	Number Of Financing Receivables Equal To Greater Than Ninety Days NumberOfFinancingReceivablesEqualToGreaterThanNinetyDays	82	loan
CY2020Q4	indb	Number Of Financing Receivables Total Past Due NumberOfFinancingReceivablesTotalPastDue	408	loan
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	9371470000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	9392866000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	1000	USD
CY2021Q4	indb	Tdrs Recorded Investment On Accrual Status TdrsRecordedInvestmentOnAccrualStatus	14635000	USD
CY2020Q4	indb	Tdrs Recorded Investment On Accrual Status TdrsRecordedInvestmentOnAccrualStatus	16983000	USD
CY2021Q4	indb	Tdrs Recorded Investment On Nonaccrual Status TdrsRecordedInvestmentOnNonaccrualStatus	1993000	USD
CY2020Q4	indb	Tdrs Recorded Investment On Nonaccrual Status TdrsRecordedInvestmentOnNonaccrualStatus	22209000	USD
CY2021Q4	indb	Financing Receivable Recorded Investment Trouble Debt Restructuring FinancingReceivableRecordedInvestmentTroubleDebtRestructuring	16628000	USD
CY2020Q4	indb	Financing Receivable Recorded Investment Trouble Debt Restructuring FinancingReceivableRecordedInvestmentTroubleDebtRestructuring	39192000	USD
CY2021Q4	indb	Additional Commitments To Lend To Borrower For Trouble Debt Restructuring AdditionalCommitmentsToLendToBorrowerForTroubleDebtRestructuring	190000	USD
CY2020Q4	indb	Additional Commitments To Lend To Borrower For Trouble Debt Restructuring AdditionalCommitmentsToLendToBorrowerForTroubleDebtRestructuring	263000	USD
CY2021	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	8	contract
CY2021	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	18301000	USD
CY2021	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	18301000	USD
CY2020	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	30	contract
CY2020	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	4908000	USD
CY2020	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	4967000	USD
	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	13	contract
	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	2189000	USD
	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	2231000	USD
CY2021	us-gaap	Financing Receivable Troubled Debt Restructuring Increase Decrease From Modification FinancingReceivableTroubledDebtRestructuringIncreaseDecreaseFromModification	18301000	USD
CY2020	us-gaap	Financing Receivable Troubled Debt Restructuring Increase Decrease From Modification FinancingReceivableTroubledDebtRestructuringIncreaseDecreaseFromModification	4967000	USD
CY2019	us-gaap	Financing Receivable Troubled Debt Restructuring Increase Decrease From Modification FinancingReceivableTroubledDebtRestructuringIncreaseDecreaseFromModification	2231000	USD
CY2021	indb	Days To Be Termed As Non Accrual Loans DaysToBeTermedAsNonAccrualLoans	P90D
CY2021	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	3200000	USD
CY2020	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
CY2019	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	64293000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	5205000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	2652000	USD
CY2019	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	6000000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	67740000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	39242000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance	56605000	USD
CY2019	us-gaap	Impaired Financing Receivable With No Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment	49077000	USD
CY2020	us-gaap	Impaired Financing Receivable With No Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod	1090000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With Related Allowance Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment	10386000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance	11535000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	980000	USD
CY2019	us-gaap	Impaired Financing Receivable With Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment	10605000	USD
CY2019	us-gaap	Impaired Financing Receivable With Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod	447000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	49628000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	68140000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	980000	USD
CY2019	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	59682000	USD
CY2019	us-gaap	Impaired Financing Receivable Interest Income Cash Basis Method ImpairedFinancingReceivableInterestIncomeCashBasisMethod	1537000	USD
CY2021Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	307134000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	216476000	USD
CY2021Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	111544000	USD
CY2020Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	100083000	USD
CY2021Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	195590000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	116393000	USD
CY2021	us-gaap	Depreciation Depreciation	12500000	USD
CY2020	us-gaap	Depreciation Depreciation	12800000	USD
CY2019	us-gaap	Depreciation Depreciation	11400000	USD
CY2021	us-gaap	Rental Income Nonoperating RentalIncomeNonoperating	890000	USD
CY2020	us-gaap	Rental Income Nonoperating RentalIncomeNonoperating	1500000	USD
CY2021Q4	us-gaap	Goodwill Goodwill	985072000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	506206000	USD
CY2021Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	32772000	USD
CY2020Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	23107000	USD
CY2021Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	1017844000	USD
CY2020Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	529313000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	506206000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	506206000	USD
CY2020	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	0	USD
CY2021Q4	us-gaap	Goodwill Goodwill	985072000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	506206000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	55310000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	22538000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	32772000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	41054000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	17947000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	23107000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	7662000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	6884000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	5911000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	4720000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	2824000	USD
CY2021Q4	us-gaap	Acquired Finite Lived Intangible Assets Weighted Average Useful Life AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife	P9Y6M
CY2021Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	1216437000	USD
CY2021Q4	indb	Time Deposit Maturities Next Twelve Months Percent Of Total TimeDepositMaturitiesNextTwelveMonthsPercentOfTotal	0.794
CY2020Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	789237000	USD
CY2020Q4	indb	Time Deposit Maturities Next Twelve Months Percent Of Total TimeDepositMaturitiesNextTwelveMonthsPercentOfTotal	0.830
CY2021Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	142942000	USD
CY2021Q4	indb	Time Deposit Maturities Year Two Percent Of Total TimeDepositMaturitiesYearTwoPercentOfTotal	0.093
CY2020Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	93727000	USD
CY2020Q4	indb	Time Deposit Maturities Year Two Percent Of Total TimeDepositMaturitiesYearTwoPercentOfTotal	0.099
CY2021Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	85650000	USD
CY2021Q4	indb	Time Deposit Maturities Year Three Percent Of Total TimeDepositMaturitiesYearThreePercentOfTotal	0.056
CY2020Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	36739000	USD
CY2020Q4	indb	Time Deposit Maturities Year Three Percent Of Total TimeDepositMaturitiesYearThreePercentOfTotal	0.039
CY2021Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	66907000	USD
CY2021Q4	indb	Time Deposit Maturities Year Four Percent Of Total TimeDepositMaturitiesYearFourPercentOfTotal	0.044
CY2020Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	13407000	USD
CY2020Q4	indb	Time Deposit Maturities Year Four Percent Of Total TimeDepositMaturitiesYearFourPercentOfTotal	0.014
CY2021Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	19214000	USD
CY2021Q4	indb	Time Deposit Maturities Year Five Percent Of Total TimeDepositMaturitiesYearFivePercentOfTotal	0.013
CY2020Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	17519000	USD
CY2020Q4	indb	Time Deposit Maturities Year Five Percent Of Total TimeDepositMaturitiesYearFivePercentOfTotal	0.018
CY2021Q4	us-gaap	Time Deposits TimeDeposits	1531150000	USD
CY2021Q4	indb	Time Deposits Percent Of Total TimeDepositsPercentOfTotal	1.000
CY2020Q4	us-gaap	Time Deposits TimeDeposits	950629000	USD
CY2020Q4	indb	Time Deposits Percent Of Total TimeDepositsPercentOfTotal	1.000
CY2021Q4	us-gaap	Deposit Liabilities Reclassified As Loans Receivable1 DepositLiabilitiesReclassifiedAsLoansReceivable1	1500000	USD
CY2020Q4	us-gaap	Deposit Liabilities Reclassified As Loans Receivable1 DepositLiabilitiesReclassifiedAsLoansReceivable1	1400000	USD
CY2021Q4	us-gaap	Deposit Liabilities Collateral Issued Financial Instruments DepositLiabilitiesCollateralIssuedFinancialInstruments	740600000	USD
CY2020Q4	us-gaap	Deposit Liabilities Collateral Issued Financial Instruments DepositLiabilitiesCollateralIssuedFinancialInstruments	419600000	USD
CY2021Q4	indb	Certificatesof Depositsover250000.00 CertificatesofDepositsover250000.00	339300000	USD
CY2020Q4	indb	Certificatesof Depositsover250000.00 CertificatesofDepositsover250000.00	202200000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due Within One Year Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueWithinOneYearOfBalanceSheetDate	35042000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate Of Amounts Due Within One Year Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueWithinOneYearOfBalanceSheetDate	0.0112
CY2021Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due Within One Year Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueWithinOneYearOfBalanceSheetDate	25000000	USD
CY2021Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate Of Amounts Due Within One Year Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueWithinOneYearOfBalanceSheetDate	0.0034
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due From One To Two Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromOneToTwoYearsOfBalanceSheetDate	0	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate One To Two Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOneToTwoYearsFromBalanceSheetDate	0
CY2021Q4	us-gaap	Federal Home Loan Bank Advances Branch Of Fhlb Bank Amount Of Advances By Branch FederalHomeLoanBankAdvancesBranchOfFHLBBankAmountOfAdvancesByBranch	25000000	USD
CY2021Q4	us-gaap	Federal Home Loan Bank Advances Weighted Average Interest Rate FederalHomeLoanBankAdvancesWeightedAverageInterestRate	0.0034
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Branch Of Fhlb Bank Amount Of Advances By Branch FederalHomeLoanBankAdvancesBranchOfFHLBBankAmountOfAdvancesByBranch	35042000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Weighted Average Interest Rate FederalHomeLoanBankAdvancesWeightedAverageInterestRate	0.0112
CY2021Q4	us-gaap	Debt Instrument Unamortized Premium DebtInstrumentUnamortizedPremium	667000	USD
CY2020Q4	us-gaap	Debt Instrument Unamortized Premium DebtInstrumentUnamortizedPremium	698000	USD
CY2021Q4	indb	Total Federal Home Loan Bank Advances TotalFederalHomeLoanBankAdvances	25667000	USD
CY2020Q4	indb	Total Federal Home Loan Bank Advances TotalFederalHomeLoanBankAdvances	35740000	USD
CY2021Q4	indb	Federal Home Loan Bank Advances Weighted Average Interest Rateinclusiveof Swaps FederalHomeLoanBankAdvancesWeightedAverageInterestRateinclusiveofSwaps	0.0205
CY2020Q4	indb	Federal Home Loan Bank Advances Weighted Average Interest Rateinclusiveof Swaps FederalHomeLoanBankAdvancesWeightedAverageInterestRateinclusiveofSwaps	0.0230
CY2021Q4	us-gaap	Loans Pledged As Collateral LoansPledgedAsCollateral	2300000000	USD
CY2020Q4	us-gaap	Loans Pledged As Collateral LoansPledgedAsCollateral	2100000000	USD
CY2021Q4	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	0	USD
CY2021	us-gaap	Interest Expense Short Term Borrowings InterestExpenseShortTermBorrowings	0	USD
CY2019	us-gaap	Interest Expense Short Term Borrowings InterestExpenseShortTermBorrowings	104000	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	0	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	112888000	USD
CY2021Q4	us-gaap	Secured Debt SecuredDebt	14063000	USD
CY2020Q4	us-gaap	Secured Debt SecuredDebt	32773000	USD
CY2021Q4	us-gaap	Subordinated Debt SubordinatedDebt	49791000	USD
CY2020Q4	us-gaap	Subordinated Debt SubordinatedDebt	49696000	USD
CY2021Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	126707000	USD
CY2020Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	145320000	USD
CY2021	us-gaap	Interest Expense Long Term Debt InterestExpenseLongTermDebt	4500000	USD
CY2020	us-gaap	Interest Expense Long Term Debt InterestExpenseLongTermDebt	5400000	USD
CY2019	us-gaap	Interest Expense Long Term Debt InterestExpenseLongTermDebt	8200000	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	14063000	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	0	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	0	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	0	USD
CY2021Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	126951000	USD
CY2021	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	4309000	USD
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	4123000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	4403000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	1212000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	1159000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	1238000	USD
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2021Q4	indb	Share Based Compensation Arrangement By Share Based Payment Award Options Price Per Share Common Stock Average High And Low Price Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsPricePerShareCommonStockAverageHighAndLowPriceIntrinsicValue	81.65
CY2021	us-gaap	Maximum Length Of Time Hedged In Interest Rate Cash Flow Hedge1 MaximumLengthOfTimeHedgedInInterestRateCashFlowHedge1	P7Y2M12D
CY2020	indb	Other Comprehensive Income Loss Reclassification Adjustmentfrom Aoc Ifor Losson Terminationof Derivativesbefore Tax OtherComprehensiveIncomeLossReclassificationAdjustmentfromAOCIforLossonTerminationofDerivativesbeforeTax	-684000	USD
CY2020Q4	us-gaap	Fair Value Hedges At Fair Value Net FairValueHedgesAtFairValueNet	0	USD
CY2021Q4	us-gaap	Fair Value Hedges At Fair Value Net FairValueHedgesAtFairValueNet	0	USD
CY2019Q4	us-gaap	Fair Value Hedges At Fair Value Net FairValueHedgesAtFairValueNet	0	USD
CY2021	indb	Change In Fair Value On Loans Held For Sale ChangeInFairValueOnLoansHeldForSale	-1700000	USD
CY2020	indb	Change In Fair Value On Loans Held For Sale ChangeInFairValueOnLoansHeldForSale	1300000	USD
CY2019	indb	Change In Fair Value On Loans Held For Sale ChangeInFairValueOnLoansHeldForSale	822000	USD
CY2021	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	19900000	USD
CY2020	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	30100000	USD
CY2019	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	13200000	USD
CY2021Q4	us-gaap	Derivative Assets DerivativeAssets	92185000	USD
CY2020Q4	us-gaap	Derivative Assets DerivativeAssets	187422000	USD
CY2021Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	69246000	USD
CY2020Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	117959000	USD
CY2021Q4	us-gaap	Derivative Collateral Obligation To Return Securities DerivativeCollateralObligationToReturnSecurities	28318000	USD
CY2020Q4	us-gaap	Derivative Collateral Obligation To Return Securities DerivativeCollateralObligationToReturnSecurities	48786000	USD
CY2021Q4	us-gaap	Derivative Collateral Right To Reclaim Securities DerivativeCollateralRightToReclaimSecurities	28318000	USD
CY2020Q4	us-gaap	Derivative Collateral Right To Reclaim Securities DerivativeCollateralRightToReclaimSecurities	48786000	USD
CY2021Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	0	USD
CY2020Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	0	USD
CY2021Q4	us-gaap	Derivative Collateral Right To Reclaim Cash DerivativeCollateralRightToReclaimCash	33838000	USD
CY2020Q4	us-gaap	Derivative Collateral Right To Reclaim Cash DerivativeCollateralRightToReclaimCash	62460000	USD
CY2021Q4	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	63867000	USD
CY2020Q4	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	138636000	USD
CY2021Q4	us-gaap	Derivative Fair Value Of Derivative Liability Amount Offset Against Collateral DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral	7090000	USD
CY2020Q4	us-gaap	Derivative Fair Value Of Derivative Liability Amount Offset Against Collateral DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral	6713000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	18691000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	2346000	USD
CY2021	indb	Other Comprehensive Income Loss Reclassification Adjustmentfrom Aoc Ifor Losson Terminationof Derivativesbefore Tax OtherComprehensiveIncomeLossReclassificationAdjustmentfromAOCIforLossonTerminationofDerivativesbeforeTax	0	USD
CY2020	indb	Other Comprehensive Income Loss Reclassification Adjustmentfrom Aoc Ifor Losson Terminationof Derivativesbefore Tax OtherComprehensiveIncomeLossReclassificationAdjustmentfromAOCIforLossonTerminationofDerivativesbeforeTax	-684000	USD
CY2021Q4	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	34800000	USD
CY2020Q4	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	79800000	USD
CY2021Q4	indb	Exposureto Institutional Counterparties ExposuretoInstitutionalCounterparties	28300000	USD
CY2020Q4	indb	Exposureto Institutional Counterparties ExposuretoInstitutionalCounterparties	48800000	USD
CY2021Q4	indb	Exposure To Counterparties Relating To Customer Related Positions ExposureToCounterpartiesRelatingToCustomerRelatedPositions	62400000	USD
CY2020Q4	indb	Exposure To Counterparties Relating To Customer Related Positions ExposureToCounterpartiesRelatingToCustomerRelatedPositions	127200000	USD
CY2021	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	21539000	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	32171000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	27980000	USD
CY2021	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	11054000	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	17004000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	14359000	USD
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	32593000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	49175000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	42339000	USD
CY2021	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	3032000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-10872000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	9080000	USD
CY2021	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	58000	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-6634000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	1514000	USD
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	3090000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-17506000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	10594000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	35683000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	31669000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	52933000	USD
CY2021	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	32902000	USD
CY2021	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.2100
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	32096000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.2100
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	45803000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.2100
CY2021	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	8754000	USD
CY2021	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.0559
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	8147000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.0533
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	12262000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.0563
CY2021	indb	Effective Income Tax Rate Reconciliation Cares Act Amount EffectiveIncomeTaxRateReconciliationCARESActAmount	0	USD
CY2021	indb	Effective Income Tax Rate Reconciliation Cares Act Percent EffectiveIncomeTaxRateReconciliationCARESActPercent	0
CY2020	indb	Effective Income Tax Rate Reconciliation Cares Act Amount EffectiveIncomeTaxRateReconciliationCARESActAmount	-4809000	USD
CY2020	indb	Effective Income Tax Rate Reconciliation Cares Act Percent EffectiveIncomeTaxRateReconciliationCARESActPercent	-0.0315
CY2019	indb	Effective Income Tax Rate Reconciliation Cares Act Amount EffectiveIncomeTaxRateReconciliationCARESActAmount	0	USD
CY2019	indb	Effective Income Tax Rate Reconciliation Cares Act Percent EffectiveIncomeTaxRateReconciliationCARESActPercent	0
CY2021	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	26000	USD
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance	0.0002
CY2020	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	0	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance	0
CY2019	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	17000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance	0.0001
CY2021	indb	Effective Income Tax Rate Reconciliation Increasein Cash Surrender Valueof Life Insurance Amount EffectiveIncomeTaxRateReconciliationIncreaseinCashSurrenderValueofLifeInsuranceAmount	1405000	USD
CY2021	indb	Effective Income Tax Rate Reconciliation Increasein Cash Surrender Valueof Life Insurance Percent EffectiveIncomeTaxRateReconciliationIncreaseinCashSurrenderValueofLifeInsurancePercent	-0.0090
CY2020	indb	Effective Income Tax Rate Reconciliation Increasein Cash Surrender Valueof Life Insurance Amount EffectiveIncomeTaxRateReconciliationIncreaseinCashSurrenderValueofLifeInsuranceAmount	1345000	USD
CY2020	indb	Effective Income Tax Rate Reconciliation Increasein Cash Surrender Valueof Life Insurance Percent EffectiveIncomeTaxRateReconciliationIncreaseinCashSurrenderValueofLifeInsurancePercent	-0.0088
CY2019	indb	Effective Income Tax Rate Reconciliation Increasein Cash Surrender Valueof Life Insurance Amount EffectiveIncomeTaxRateReconciliationIncreaseinCashSurrenderValueofLifeInsuranceAmount	1144000	USD
CY2019	indb	Effective Income Tax Rate Reconciliation Increasein Cash Surrender Valueof Life Insurance Percent EffectiveIncomeTaxRateReconciliationIncreaseinCashSurrenderValueofLifeInsurancePercent	-0.0052
CY2021	us-gaap	Income Tax Reconciliation Tax Credits Investment IncomeTaxReconciliationTaxCreditsInvestment	2308000	USD
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Investment EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment	-0.0147
CY2020	us-gaap	Income Tax Reconciliation Tax Credits Investment IncomeTaxReconciliationTaxCreditsInvestment	1851000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Investment EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment	-0.0121
CY2019	us-gaap	Income Tax Reconciliation Tax Credits Investment IncomeTaxReconciliationTaxCreditsInvestment	1696000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Investment EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment	-0.0078
CY2021	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	630000	USD
CY2021	indb	Effective Income Tax Rate Reconciliation Merger And Other Related Costs EffectiveIncomeTaxRateReconciliationMergerAndOtherRelatedCosts	0.0040
CY2020	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	0	USD
CY2020	indb	Effective Income Tax Rate Reconciliation Merger And Other Related Costs EffectiveIncomeTaxRateReconciliationMergerAndOtherRelatedCosts	0
CY2019	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	582000	USD
CY2019	indb	Effective Income Tax Rate Reconciliation Merger And Other Related Costs EffectiveIncomeTaxRateReconciliationMergerAndOtherRelatedCosts	0.0027
CY2021	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	0	USD
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0
CY2020	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	0	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0
CY2019	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	2675000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	-0.0123
CY2021	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	1022000	USD
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	-0.0065
CY2020	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	723000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	-0.0047
CY2019	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	757000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	-0.0035
CY2021	indb	Effective Income Tax Rate Reconciliation Stock Based Compensation Amount EffectiveIncomeTaxRateReconciliationStockBasedCompensationAmount	372000	USD
CY2021	indb	Effective Income Tax Rate Reconciliation Stock Based Compensation Percent EffectiveIncomeTaxRateReconciliationStockBasedCompensationPercent	-0.0024
CY2020	indb	Effective Income Tax Rate Reconciliation Stock Based Compensation Amount EffectiveIncomeTaxRateReconciliationStockBasedCompensationAmount	1067000	USD
CY2020	indb	Effective Income Tax Rate Reconciliation Stock Based Compensation Percent EffectiveIncomeTaxRateReconciliationStockBasedCompensationPercent	-0.0070
CY2019	indb	Effective Income Tax Rate Reconciliation Stock Based Compensation Amount EffectiveIncomeTaxRateReconciliationStockBasedCompensationAmount	824000	USD
CY2019	indb	Effective Income Tax Rate Reconciliation Stock Based Compensation Percent EffectiveIncomeTaxRateReconciliationStockBasedCompensationPercent	-0.0038
CY2021	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-1522000	USD
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Other Reconciling Items Percent EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent	-0.0097
CY2020	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	1221000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Other Reconciling Items Percent EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent	0.0080
CY2019	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	1365000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Reconciling Items Percent EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent	0.0063
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	35683000	USD
CY2021	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.2278
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	31669000	USD
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.2072
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	52933000	USD
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.2428
CY2020	indb	Effective Income Tax Rate Reconciliation Cares Act Amount EffectiveIncomeTaxRateReconciliationCARESActAmount	-4800000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	15909000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	13804000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	41541000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	32265000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	1489000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	1548000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Foreign DeferredTaxAssetsTaxCreditCarryforwardsForeign	89000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Foreign DeferredTaxAssetsTaxCreditCarryforwardsForeign	89000	USD
CY2021Q4	indb	Deferred Tax Asset Loan Fair Value Adjustment DeferredTaxAssetLoanFairValueAdjustment	2286000	USD
CY2020Q4	indb	Deferred Tax Asset Loan Fair Value Adjustment DeferredTaxAssetLoanFairValueAdjustment	4791000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	637000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	226000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Unrealized Losses On Availablefor Sale Securities Gross DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	2921000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Unrealized Losses On Availablefor Sale Securities Gross DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	0	USD
CY2021Q4	indb	Deferred Tax Asset Operating Lease Liability DeferredTaxAssetOperatingLeaseLiability	17970000	USD
CY2020Q4	indb	Deferred Tax Asset Operating Lease Liability DeferredTaxAssetOperatingLeaseLiability	15846000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	1188000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	999000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	84030000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	69568000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	306000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	280000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	83724000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	69288000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	5927000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	4344000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Financing Costs DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts	6107000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Financing Costs DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts	336000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Derivatives DeferredTaxLiabilitiesDerivatives	5536000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Derivatives DeferredTaxLiabilitiesDerivatives	13036000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	18437000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	7786000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Goodwill DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill	11249000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Goodwill DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill	10947000	USD
CY2021Q4	indb	Deferred Tax Liabilities Unrealized Gains On Available For Sale DeferredTaxLiabilitiesUnrealizedGainsOnAvailableForSale	0	USD
CY2020Q4	indb	Deferred Tax Liabilities Unrealized Gains On Available For Sale DeferredTaxLiabilitiesUnrealizedGainsOnAvailableForSale	4152000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Prepaid Expenses DeferredTaxLiabilitiesPrepaidExpenses	3296000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Prepaid Expenses DeferredTaxLiabilitiesPrepaidExpenses	3404000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	16829000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	12979000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	1825000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	1573000	USD
CY2021Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	69206000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	58557000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	14518000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	10731000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Foreign DeferredTaxAssetsTaxCreditCarryforwardsForeign	89000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	532000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	58000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	474000	USD
CY2021	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	29000	USD
CY2021	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	2433000	USD
CY2021Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	2878000	USD
CY2021	indb	Unrecognized Tax Benefits Increase Resultingfrom Current Period Tax Positionsfederalbenefitofstatetaxamount UnrecognizedTaxBenefitsIncreaseResultingfromCurrentPeriodTaxPositionsfederalbenefitofstatetaxamount	604000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	95000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	43000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	53000	USD
CY2021	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	69000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	52000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	10000	USD
CY2021	indb	Acquired Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued AcquiredUnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	756000	USD
CY2021Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	920000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	95000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	43000	USD
CY2021Q4	indb	Original Investmentin Low Income Housing Projects OriginalInvestmentinLowIncomeHousingProjects	179481000	USD
CY2020Q4	indb	Original Investmentin Low Income Housing Projects OriginalInvestmentinLowIncomeHousingProjects	128752000	USD
CY2019Q4	indb	Original Investmentin Low Income Housing Projects OriginalInvestmentinLowIncomeHousingProjects	96275000	USD
CY2021Q4	us-gaap	Amortization Method Qualified Affordable Housing Project Investments AmortizationMethodQualifiedAffordableHousingProjectInvestments	135497000	USD
CY2020Q4	us-gaap	Amortization Method Qualified Affordable Housing Project Investments AmortizationMethodQualifiedAffordableHousingProjectInvestments	97435000	USD
CY2018Q4	us-gaap	Amortization Method Qualified Affordable Housing Project Investments AmortizationMethodQualifiedAffordableHousingProjectInvestments	72510000	USD
CY2021Q4	us-gaap	Qualified Affordable Housing Project Investments Commitment QualifiedAffordableHousingProjectInvestmentsCommitment	73336000	USD
CY2020Q4	us-gaap	Qualified Affordable Housing Project Investments Commitment QualifiedAffordableHousingProjectInvestmentsCommitment	49586000	USD
CY2018Q4	us-gaap	Qualified Affordable Housing Project Investments Commitment QualifiedAffordableHousingProjectInvestmentsCommitment	34967000	USD
CY2021	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	14198000	USD
	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	9404000	USD
CY2019	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	7342000	USD
CY2021	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	11892000	USD
	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	7552000	USD
CY2019	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	5645000	USD
CY2021	us-gaap	Income Loss From Affordable Housing Projects Equity Method Investments IncomeLossFromAffordableHousingProjectsEquityMethodInvestments	2306000	USD
	us-gaap	Income Loss From Affordable Housing Projects Equity Method Investments IncomeLossFromAffordableHousingProjectsEquityMethodInvestments	1851000	USD
CY2019	us-gaap	Income Loss From Affordable Housing Projects Equity Method Investments IncomeLossFromAffordableHousingProjectsEquityMethodInvestments	1696000	USD
CY2021	us-gaap	Multiemployer Plan Pension Significant Funded Status Fixed List MultiemployerPlanPensionSignificantFundedStatusFixedList	At least 80 percent
CY2020	us-gaap	Multiemployer Plan Pension Significant Funded Status Fixed List MultiemployerPlanPensionSignificantFundedStatusFixedList	At least 80 percent
CY2021	us-gaap	Multiemployer Plan Pension Significant Funding Improvement Or Rehabilitation Plan Implementation Status Fixed List MultiemployerPlanPensionSignificantFundingImprovementOrRehabilitationPlanImplementationStatusFixedList	No
CY2021	us-gaap	Multiemployer Plan Pension Significant Surcharge Fixed List MultiemployerPlanPensionSignificantSurchargeFixedList	No
CY2021	us-gaap	Multiemployer Plans Collective Bargaining Arrangement Expiration Date Description MultiemployerPlansCollectiveBargainingArrangementExpirationDateDescription	N/A
CY2021	us-gaap	Multiemployer Plan Pension Significant Future Employer Contribution Amount MultiemployerPlanPensionSignificantFutureEmployerContributionAmount	0	USD
CY2021	indb	Multiemployer Plans Period Contributions Significance Of Contributions Percentage MultiemployerPlansPeriodContributionsSignificanceOfContributionsPercentage	0.05
CY2021	us-gaap	Pension Expense PensionExpense	1200000	USD
CY2020	us-gaap	Pension Expense PensionExpense	1900000	USD
CY2019	us-gaap	Pension Expense PensionExpense	1400000	USD
CY2021	indb	Defined Benefit Plan Requisite Age DefinedBenefitPlanRequisiteAge	65	age
CY2021	indb	Defined Benefit Plan Requisite Service Period DefinedBenefitPlanRequisiteServicePeriod	P10Y
CY2021	indb	Defined Benefit Plan Death Benefit DefinedBenefitPlanDeathBenefit	5000	USD
CY2021Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	20300000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	19100000	USD
CY2021	indb	Incentive Plans And Discretionary Bonus Expense IncentivePlansAndDiscretionaryBonusExpense	21200000	USD
CY2020	indb	Incentive Plans And Discretionary Bonus Expense IncentivePlansAndDiscretionaryBonusExpense	11000000	USD
CY2019	indb	Incentive Plans And Discretionary Bonus Expense IncentivePlansAndDiscretionaryBonusExpense	16300000	USD
CY2021	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent DefinedContributionPlanEmployerMatchingContributionPercent	0.25
CY2021	us-gaap	Defined Contribution Plan Maximum Annual Contributions Per Employee Percent DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent	0.06
CY2021	indb	Defined Contribution Plan Nondiscretionary Requisite Service Period DefinedContributionPlanNondiscretionaryRequisiteServicePeriod	P1Y
CY2021	indb	Defined Contribution Plan Nondiscretionary Requisiteservicehours DefinedContributionPlanNondiscretionaryRequisiteservicehours	1,000
CY2021	indb	Defined Contribution Plan Employer Safe Harbor Contribution Amount DefinedContributionPlanEmployerSafeHarborContributionAmount	0.03
CY2021	indb	Defined Contribution Plan Employer Discretionary Contribution Percentageupto Social Security Limit DefinedContributionPlanEmployerDiscretionaryContributionPercentageuptoSocialSecurityLimit	0.02
CY2021	indb	Defined Contribution Plan Nondiscretionary Employer Contribution Percent Over Social Security Limit DefinedContributionPlanNondiscretionaryEmployerContributionPercentOverSocialSecurityLimit	0.05
CY2021	us-gaap	Deferred Compensation Arrangement With Individual Contributions By Employer DeferredCompensationArrangementWithIndividualContributionsByEmployer	84000	USD
CY2020	us-gaap	Deferred Compensation Arrangement With Individual Contributions By Employer DeferredCompensationArrangementWithIndividualContributionsByEmployer	101000	USD
CY2019	us-gaap	Deferred Compensation Arrangement With Individual Contributions By Employer DeferredCompensationArrangementWithIndividualContributionsByEmployer	180000	USD
CY2021	indb	Othernoninterestincome Asc606 OthernoninterestincomeASC606	5312000	USD
CY2020	indb	Othernoninterestincome Asc606 OthernoninterestincomeASC606	4235000	USD
CY2019	indb	Othernoninterestincome Asc606 OthernoninterestincomeASC606	8696000	USD
CY2021	indb	Totalnoninterestincomeinscopeof Asc606 TotalnoninterestincomeinscopeofASC606	71809000	USD
CY2020	indb	Totalnoninterestincomeinscopeof Asc606 TotalnoninterestincomeinscopeofASC606	65905000	USD
CY2019	indb	Totalnoninterestincomeinscopeof Asc606 TotalnoninterestincomeinscopeofASC606	80116000	USD
CY2021	indb	Totalnoninterestincomeoutofscopeof Asc606 TotalnoninterestincomeoutofscopeofASC606	34041000	USD
CY2020	indb	Totalnoninterestincomeoutofscopeof Asc606 TotalnoninterestincomeoutofscopeofASC606	45535000	USD
CY2019	indb	Totalnoninterestincomeoutofscopeof Asc606 TotalnoninterestincomeoutofscopeofASC606	35178000	USD
CY2021	us-gaap	Noninterest Income NoninterestIncome	105850000	USD
CY2020	us-gaap	Noninterest Income NoninterestIncome	111440000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	115294000	USD
CY2021Q4	indb	Investment Management Income Receivable InvestmentManagementIncomeReceivable	5385000	USD
CY2020Q4	indb	Investment Management Income Receivable InvestmentManagementIncomeReceivable	4636000	USD
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-29995000	USD
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-7073000	USD
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-22922000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	0	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	0	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	0	USD
CY2021	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Before Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent	-29995000	USD
CY2021	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	-7073000	USD
CY2021	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	-22922000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	-7938000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax	-2234000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-5704000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	18691000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax	5256000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax	13435000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax	-26629000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax	-7490000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	-19139000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	3414000	USD
CY2021	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	960000	USD
CY2021	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	2454000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-1331000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-374000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-957000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	192000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	54000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	138000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-4937000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-1388000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-3549000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	-51687000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	-13175000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-38512000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	11686000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	2829000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	8857000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Before Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent	11686000	USD
CY2020	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	2829000	USD
CY2020	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	8857000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	36994000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax	10406000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	26588000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	14306000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax	4023000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax	10283000	USD
CY2020	indb	Other Comprehensive Income Loss Reclassification Adjustmentfrom Aoc Ifor Losson Terminationof Derivativesbefore Tax OtherComprehensiveIncomeLossReclassificationAdjustmentfromAOCIforLossonTerminationofDerivativesbeforeTax	-684000	USD
CY2020	indb	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Loss On Termination Of Derivatives Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForLossOnTerminationOfDerivativesTax	-192000	USD
CY2020	indb	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Loss On Termination Of Derivatives After Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForLossOnTerminationOfDerivativesAfterTax	-492000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax	23372000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax	6575000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	16797000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-5785000	USD
CY2020	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	-1627000	USD
CY2020	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-4158000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-982000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-276000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-706000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	276000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	78000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	198000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Finalization Of Pension And Non Pension Postretirement Plan Valuation Before Tax OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax	176000	USD
CY2020	us-gaap	Other Comprehensive Income Finalization Of Pension And Non Pension Postretirement Plan Valuation Tax OtherComprehensiveIncomeFinalizationOfPensionAndNonPensionPostretirementPlanValuationTax	50000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Finalization Of Pension And Non Pension Postretirement Plan Valuation Net Of Tax OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationNetOfTax	126000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	4351000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	1223000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	3128000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	30707000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	8181000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	22526000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	12055000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	2761000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	9294000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-1462000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-411000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-1051000	USD
CY2019	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Before Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent	13517000	USD
CY2019	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	3172000	USD
CY2019	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	10345000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	16725000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax	4708000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	12017000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	2346000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax	660000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax	1686000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax	14379000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax	4048000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	10331000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-2123000	USD
CY2019	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	-597000	USD
CY2019	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-1526000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	8000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	2000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	6000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	276000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	78000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	198000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	1855000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	521000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	1334000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	26041000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	6699000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	19342000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	16881000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-1173000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	19342000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	18169000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	22526000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	40695000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-38512000	USD
CY2021Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	2183000	USD
CY2021Q4	us-gaap	Property Subject To Or Available For Operating Lease Number Of Units PropertySubjectToOrAvailableForOperatingLeaseNumberOfUnits	126
CY2021Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	60200000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	49700000	USD
CY2020	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	4200000	USD
CY2021	us-gaap	Operating Lease Cost OperatingLeaseCost	14550000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	10718000	USD
CY2021	us-gaap	Short Term Lease Cost ShortTermLeaseCost	23000	USD
CY2020	us-gaap	Short Term Lease Cost ShortTermLeaseCost	16000	USD
CY2019	us-gaap	Short Term Lease Cost ShortTermLeaseCost	116000	USD
CY2021	us-gaap	Variable Lease Cost VariableLeaseCost	0	USD
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	0	USD
CY2019	us-gaap	Variable Lease Cost VariableLeaseCost	0	USD
CY2021	us-gaap	Lease Cost LeaseCost	14573000	USD
CY2020	us-gaap	Lease Cost LeaseCost	16897000	USD
CY2019	us-gaap	Lease Cost LeaseCost	10834000	USD
CY2021Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P5Y8M19D
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P5Y7M2D
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P6Y5M4D
CY2021Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0197
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0213
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0275
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	16288000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	12349000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	10585000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	9406000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	7028000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	12038000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	67694000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	3786000	USD
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	63908000	USD
CY2021	us-gaap	Cash Dividends Paid To Parent Company By Consolidated Subsidiaries CashDividendsPaidToParentCompanyByConsolidatedSubsidiaries	77600000	USD
CY2020	us-gaap	Cash Dividends Paid To Parent Company By Consolidated Subsidiaries CashDividendsPaidToParentCompanyByConsolidatedSubsidiaries	166000000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	26343000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	55830000	USD
CY2021	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	57983000	USD
CY2020	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	45308000	USD
CY2021	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	39293000	USD
CY2020	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	74795000	USD
CY2021Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	45033000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	26343000	USD
CY2021	indb	Nonaccrual Tdr Loanswithrelatedparties NonaccrualTDRLoanswithrelatedparties	0	USD
CY2020	indb	Nonaccrual Tdr Loanswithrelatedparties NonaccrualTDRLoanswithrelatedparties	0	USD
CY2021Q4	us-gaap	Related Party Deposit Liabilities RelatedPartyDepositLiabilities	22300000	USD
CY2020Q4	us-gaap	Related Party Deposit Liabilities RelatedPartyDepositLiabilities	22900000	USD
CY2020	indb	Leaseswithrelatedparties Leaseswithrelatedparties	0	USD
CY2020	indb	Leaseswithrelatedparties Leaseswithrelatedparties	0	USD
CY2021	dei	Auditor Firm AuditorFirmId	42

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INDEPENDENT BANK CORP Stock $indb

2021 Q4 Form 10-K Financial Statement

#000077690122000048 Filed on February 28, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$INDB INDEPENDENT BANK CORP Stock $indb

2021 Q4 Form 10-K Financial Statement

#000077690122000048 Filed on February 28, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$INDB
INDEPENDENT BANK CORP Stock $indb