$GBCI
GLACIER BANCORP, INC. Stock $gbci

$gbci Overview Financials Valuation SEC Filings Company Website

2021 Q1 Form 10-Q Financial Statement

#000086867121000046 Filed on May 03, 2021

Income Statement

Concept	2021 Q1	2020 Q1
Revenue	$161.6M	$142.9M
YoY Change	13.08%	13.28%
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	$7.800M	$7.300M
YoY Change	6.85%	15.87%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$4.740M	$8.496M
YoY Change	-44.21%	-22.08%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$100.3M	$52.97M
YoY Change	89.36%	-12.88%
Income Tax	$19.50M	$9.630M
% Of Pretax Income	19.44%	18.18%
Net Earnings	$80.80M	$43.34M
YoY Change	86.44%	-11.79%
Net Earnings / Revenue	50.02%	30.34%
Basic Earnings Per Share	$0.85	$0.46
Diluted Earnings Per Share	$0.85	$0.46
COMMON SHARES
Basic Shares Outstanding	95.47M shares	93.29M shares
Diluted Shares Outstanding	95.55M shares	93.36M shares

Balance Sheet

Concept	2021 Q1	2020 Q1
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$878.5M	$273.4M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$322.4M	$324.2M
YoY Change	-0.58%	16.79%
Goodwill	$514.0M	$513.4M
YoY Change	0.13%	77.27%
Intangibles
YoY Change
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	$19.77B	$15.16B
YoY Change	30.43%	25.55%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$3.000M	$5.000M
YoY Change	-40.0%	0.0%
Accrued Expenses	$49.00M	$46.00M
YoY Change	6.52%	21.05%
Deferred Revenue
YoY Change
Short-Term Debt	$997.0M	$580.0M
YoY Change	71.9%	18.37%
Long-Term Debt Due	$0.00	$0.00
YoY Change
Total Short-Term Liabilities	$52.00M	$51.00M
YoY Change	1.96%	18.6%
LONG-TERM LIABILITIES
Long-Term Debt	$166.0M	$172.0M
YoY Change	-3.49%	15.44%
Other Long-Term Liabilities	$153.0M	$132.0M
YoY Change	15.91%	33.33%
Total Long-Term Liabilities	$319.0M	$304.0M
YoY Change	4.93%	22.58%
TOTAL LIABILITIES
Total Short-Term Liabilities	$52.00M	$51.00M
Total Long-Term Liabilities	$319.0M	$304.0M
Total Liabilities	$17.48B	$13.02B
YoY Change	34.2%	23.75%
SHAREHOLDERS EQUITY
Retained Earnings	$719.1M	$544.3M
YoY Change	32.11%	14.64%
Common Stock	$1.495B	$1.492B
YoY Change	0.25%	41.89%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$2.295B	$2.137B
YoY Change
Total Liabilities & Shareholders Equity	$19.77B	$15.16B
YoY Change	30.43%	25.55%

Cashflow Statement

Concept	2021 Q1	2020 Q1
OPERATING ACTIVITIES
Net Income	$80.80M	$43.34M
YoY Change	86.44%	-11.79%
Depreciation, Depletion And Amortization	$7.800M	$7.300M
YoY Change	6.85%	15.87%
Cash From Operating Activities	$147.7M	$25.76M
YoY Change	473.5%	-44.37%
INVESTING ACTIVITIES
Capital Expenditures	-$1.600M	-$900.0K
YoY Change	77.78%	-76.32%
Acquisitions	$0.00	-$43.71M
YoY Change	-100.0%
Other Investing Activities	-$1.177B	-$719.2M
YoY Change	63.67%	-987.9%
Cash From Investing Activities	-$1.179B	-$720.1M
YoY Change	63.68%	-1032.65%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	$1.276B	$636.8M
YoY Change	100.41%	-610.36%
NET CHANGE
Cash From Operating Activities	$147.7M	$25.76M
Cash From Investing Activities	-$1.179B	-$720.1M
Cash From Financing Activities	$1.276B	$636.8M
Net Change In Cash	$245.3M	-$57.52M
YoY Change	-526.47%	4454.24%
FREE CASH FLOW
Cash From Operating Activities	$147.7M	$25.76M
Capital Expenditures	-$1.600M	-$900.0K
Free Cash Flow	$149.3M	$26.66M
YoY Change	460.14%	-46.79%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2021Q1	dei	Entity Central Index Key EntityCentralIndexKey	0000868671
CY2021Q1	dei	Amendment Flag AmendmentFlag	false
CY2021Q1	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
CY2021Q1	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q1
CY2021Q1	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2021Q1	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	1	operating_segment
CY2021Q1	dei	Document Type DocumentType	10-Q
CY2021Q1	dei	Document Quarterly Report DocumentQuarterlyReport	true
CY2021Q1	dei	Document Period End Date DocumentPeriodEndDate	2021-03-31
CY2021Q1	dei	Document Transition Report DocumentTransitionReport	false
CY2021Q1	dei	Entity File Number EntityFileNumber	000-18911
CY2021Q1	dei	Entity Registrant Name EntityRegistrantName	GLACIER BANCORP, INC.
CY2021Q1	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	MT
CY2021Q1	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	81-0519541
CY2021Q1	dei	Entity Address Address Line1 EntityAddressAddressLine1	49 Commons Loop
CY2021Q1	dei	Entity Address City Or Town EntityAddressCityOrTown	Kalispell,
CY2021Q1	dei	Entity Address State Or Province EntityAddressStateOrProvince	MT
CY2021Q1	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	59901
CY2021Q1	dei	City Area Code CityAreaCode	(406)
CY2021Q1	dei	Local Phone Number LocalPhoneNumber	756-4200
CY2021Q1	dei	Security12b Title Security12bTitle	Common Stock, $0.01 par value
CY2021Q1	dei	Trading Symbol TradingSymbol	GBCI
CY2021Q1	dei	Security Exchange Name SecurityExchangeName	NASDAQ
CY2021Q1	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2021Q1	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2021Q1	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2021Q1	dei	Entity Small Business EntitySmallBusiness	false
CY2021Q1	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2021Q1	dei	Entity Shell Company EntityShellCompany	false
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CY2021Q1	us-gaap	Goodwill Goodwill	514013000	USD
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CY2021Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	19498000	USD
CY2020Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	9630000	USD
CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	80802000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	43339000	USD
CY2021Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.85
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.46
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CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.46
CY2021Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.31
CY2020Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.29
CY2021Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	95465801	shares
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CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	80802000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	43339000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-84798000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	80555000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	326000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	862000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-85124000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	79693000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-21511000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	20195000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-63613000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	59498000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	593000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	0	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Reclassification For Discontinuance Before Tax OtherComprehensiveIncomeLossCashFlowHedgeReclassificationForDiscontinuanceBeforeTax	0	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Reclassification For Discontinuance Before Tax OtherComprehensiveIncomeLossCashFlowHedgeReclassificationForDiscontinuanceBeforeTax	0	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax	593000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax	0	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax	150000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax	0	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	443000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	0	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-63170000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	59498000	USD
CY2021Q1	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	17632000	USD
CY2020Q1	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	102837000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	1960733000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	43339000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	59498000	USD
CY2020Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.29
CY2020Q1	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	27727000	USD
CY2020Q1	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	112133000	USD
CY2020Q1	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
CY2020Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	1015000	USD
CY2020Q1	us-gaap	Stockholders Equity StockholdersEquity	2136644000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	2307041000	USD
CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	80802000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-63170000	USD
CY2021Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.31
CY2021Q1	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	29674000	USD
CY2021Q1	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
CY2021Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	386000	USD
CY2021Q1	us-gaap	Stockholders Equity StockholdersEquity	2295385000	USD
CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	80802000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	43339000	USD
CY2021Q1	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	48000	USD
CY2020Q1	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	19185000	USD
CY2021Q1	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-8562000	USD
CY2020Q1	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-3237000	USD
CY2021Q1	gbci	Accretion Amortization Of Discounts And Premiums Business Combinations AccretionAmortizationOfDiscountsAndPremiumsBusinessCombinations	-12892000	USD
CY2020Q1	gbci	Accretion Amortization Of Discounts And Premiums Business Combinations AccretionAmortizationOfDiscountsAndPremiumsBusinessCombinations	-324000	USD
CY2021Q1	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	439887000	USD
CY2020Q1	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	275256000	USD
CY2021Q1	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	509668000	USD
CY2020Q1	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	268067000	USD
CY2021Q1	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	21624000	USD
CY2020Q1	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	11862000	USD
CY2021Q1	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	284000	USD
CY2020Q1	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	863000	USD
CY2021Q1	us-gaap	Life Insurance Corporate Or Bank Owned Change In Value LifeInsuranceCorporateOrBankOwnedChangeInValue	641000	USD
CY2020Q1	us-gaap	Life Insurance Corporate Or Bank Owned Change In Value LifeInsuranceCorporateOrBankOwnedChangeInValue	656000	USD
CY2021Q1	us-gaap	Share Based Compensation ShareBasedCompensation	1491000	USD
CY2020Q1	us-gaap	Share Based Compensation ShareBasedCompensation	1199000	USD
CY2021Q1	us-gaap	Depreciation Nonproduction DepreciationNonproduction	5251000	USD
CY2020Q1	us-gaap	Depreciation Nonproduction DepreciationNonproduction	4833000	USD
CY2021Q1	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	0	USD
CY2020Q1	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	196000	USD
CY2021Q1	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2488000	USD
CY2020Q1	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2533000	USD
CY2021Q1	gbci	Variable Interest Entities Investment Amortization VariableInterestEntitiesInvestmentAmortization	3158000	USD
CY2020Q1	gbci	Variable Interest Entities Investment Amortization VariableInterestEntitiesInvestmentAmortization	2114000	USD
CY2021Q1	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	3834000	USD
CY2020Q1	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	10690000	USD
CY2021Q1	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-14036000	USD
CY2020Q1	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	9793000	USD
CY2021Q1	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-715000	USD
CY2020Q1	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-99000	USD
CY2021Q1	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-23666000	USD
CY2020Q1	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-9654000	USD
CY2021Q1	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	147745000	USD
CY2020Q1	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	25762000	USD
CY2021Q1	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	290743000	USD
CY2020Q1	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	176926000	USD
CY2021Q1	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	1302635000	USD
CY2020Q1	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	811523000	USD
CY2021Q1	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	4130000	USD
CY2020Q1	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	20250000	USD
CY2021Q1	us-gaap	Proceeds From Loan And Lease Originations And Principal Collections1 ProceedsFromLoanAndLeaseOriginationsAndPrincipalCollections1	1519493000	USD
CY2020Q1	us-gaap	Proceeds From Loan And Lease Originations And Principal Collections1 ProceedsFromLoanAndLeaseOriginationsAndPrincipalCollections1	810652000	USD
CY2021Q1	gbci	Payments For Loans Originated Or Acquired PaymentsForLoansOriginatedOrAcquired	1683608000	USD
CY2020Q1	gbci	Payments For Loans Originated Or Acquired PaymentsForLoansOriginatedOrAcquired	942157000	USD
CY2021Q1	us-gaap	Payments For Proceeds From Productive Assets PaymentsForProceedsFromProductiveAssets	1573000	USD
CY2020Q1	us-gaap	Payments For Proceeds From Productive Assets PaymentsForProceedsFromProductiveAssets	940000	USD
CY2021Q1	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	176000	USD
CY2020Q1	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	1198000	USD
CY2021Q1	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	0	USD
CY2020Q1	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	36244000	USD
CY2021Q1	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	0	USD
CY2020Q1	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	51598000	USD
CY2021Q1	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	1575000	USD
CY2020Q1	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	0	USD
CY2021Q1	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	7021000	USD
CY2020Q1	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	2895000	USD
CY2021Q1	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
CY2020Q1	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	-43713000	USD
CY2021Q1	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1178720000	USD
CY2020Q1	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-720130000	USD
CY2021Q1	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	1306824000	USD
CY2020Q1	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	178132000	USD
CY2021Q1	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	-7705000	USD
CY2020Q1	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	3263000	USD
CY2021Q1	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	0	USD
CY2020Q1	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	475000000	USD
CY2021Q1	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	0	USD
CY2020Q1	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	547000	USD
CY2021Q1	us-gaap	Proceeds From Repayments Of Other Debt ProceedsFromRepaymentsOfOtherDebt	-7116000	USD
CY2020Q1	us-gaap	Proceeds From Repayments Of Other Debt ProceedsFromRepaymentsOfOtherDebt	-5000	USD
CY2021Q1	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	14530000	USD
CY2020Q1	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	18652000	USD
CY2021Q1	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	1351000	USD
CY2020Q1	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	977000	USD
CY2021Q1	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	161000	USD
CY2020Q1	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	634000	USD
CY2021Q1	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	1276283000	USD
CY2020Q1	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	636848000	USD
CY2021Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	245308000	USD
CY2020Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-57520000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	633142000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	330961000	USD
CY2021Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	878450000	USD
CY2020Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	273441000	USD
CY2021Q1	us-gaap	Interest Paid Net InterestPaidNet	5455000	USD
CY2020Q1	us-gaap	Interest Paid Net InterestPaidNet	8595000	USD
CY2021Q1	us-gaap	Income Taxes Paid IncomeTaxesPaid	2000	USD
CY2020Q1	us-gaap	Income Taxes Paid IncomeTaxesPaid	0	USD
CY2021Q1	us-gaap	Transfer Of Investments TransferOfInvestments	403767000	USD
CY2020Q1	us-gaap	Transfer Of Investments TransferOfInvestments	0	USD
CY2021Q1	us-gaap	Transfer Of Other Real Estate TransferOfOtherRealEstate	0	USD
CY2020Q1	us-gaap	Transfer Of Other Real Estate TransferOfOtherRealEstate	215000	USD
CY2021Q1	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	1397000	USD
CY2020Q1	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	465000	USD
CY2021Q1	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	345000	USD
CY2020Q1	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	2241000	USD
CY2021Q1	gbci	Dividends Declared But Not Paid During The Period DividendsDeclaredButNotPaidDuringThePeriod	29674000	USD
CY2020Q1	gbci	Dividends Declared But Not Paid During The Period DividendsDeclaredButNotPaidDuringThePeriod	27727000	USD
CY2021Q1	us-gaap	Stock Issued1 StockIssued1	0	USD
CY2020Q1	us-gaap	Stock Issued1 StockIssued1	112133000	USD
CY2021Q1	gbci	Cash Consideration For Outstanding Shares CashConsiderationForOutstandingShares	0	USD
CY2020Q1	gbci	Cash Consideration For Outstanding Shares CashConsiderationForOutstandingShares	13721000	USD
CY2021Q1	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	0	USD
CY2020Q1	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	744109000	USD
CY2021Q1	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	0	USD
CY2020Q1	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	618255000	USD
CY2021Q1	gbci	Number Of Bank Divisions NumberOfBankDivisions	16	bankDivision
CY2021Q1	gbci	Federal Reserve Balance Or Cash On Hand Required FederalReserveBalanceOrCashOnHandRequired	0	USD
CY2021Q1	us-gaap	Financing Receivable Allowance For Credit Losses Policy For Uncollectible Amounts FinancingReceivableAllowanceForCreditLossesPolicyForUncollectibleAmounts	<div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;text-decoration:underline">Allowance for Credit Losses - Loans Receivable</span></div><div style="text-align:justify"><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 for loans receivable represents management’s estimate of credit losses over the expected contractual life of the loan portfolio. The estimate is determined based on the amortized cost of the loan portfolio including the loan balance adjusted for charge-offs, recoveries, deferred fees and costs, and loan discount and premiums. Recoveries are included only to the extent that such amounts were previously charged-off. The Company has elected to exclude accrued interest from the estimate of credit losses for loans. Determining the adequacy of the allowance is complex and requires a high degree of judgment by management about the effect of matters that are inherently uncertain. Subsequent evaluations of the then-existing loan portfolio, in light of the factors then prevailing, may result in significant changes in the allowance in those future periods.</span></div><div><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The allowance is increased for estimated credit losses which are recorded as expense. The portion of loans and overdraft balances determined by management to be uncollectable are charged-off as a reduction to the allowance and recoveries of amounts previously charged-off increase the allowance. The Company’s charge-off policy is consistent with bank regulatory standards. Consumer loans generally are charged-off when the loan becomes over 120 days delinquent. Real estate acquired as a result of foreclosure or by deed-in-lieu of foreclosure is classified as other real estate owned (“OREO”) until such time as it is sold. </span></div><div><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The expected credit loss estimate process involves procedures to consider the unique characteristics of each of the Company’s loan portfolio segments, which consist of residential real estate, commercial real estate, other commercial, home equity, and other consumer loans. When computing the allowance levels, credit loss assumptions are estimated using a model that categorizes loan pools based on loss history, credit and risk characteristics, including current conditions and reasonable and supportable forecasts about the future. The Company has determined a four consecutive quarter forecasting period is a reasonable and supportable period. Expected credit loss for periods beyond reasonable and supportable forecast periods are determined based on a reversion method which reverts back to historical loss estimate over a four consecutive quarter period on a straight-line basis.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Credit quality is assessed and monitored by evaluating various attributes and the results of those evaluations are utilized in underwriting new loans and the process for estimating the expected credit losses. The following paragraphs describe the risk characteristics relevant to each portfolio segment.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Residential Real Estate.</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> Residential real estate loans are secured by owner-occupied 1-4 family residences. Repayment of these loans is primarily dependent on the personal income and credit rating of the borrowers. Credit risk in these loans is impacted by economic conditions within the Company’s market areas that affect the value of the residential property securing the loans and affect the borrowers' personal incomes. Mitigating risk factors for this loan segment include a large number of borrowers, geographic dispersion of market areas and the loans are originated for relatively smaller amounts.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Commercial Real Estate</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">. Commercial real estate loans typically involve larger principal amounts, and repayment of these loans is generally dependent on the successful operation of the property securing the loan and/or the business conducted on the property securing the loan. Credit risk in these loans is impacted by the creditworthiness of a borrower, valuation of the property securing the loan and conditions within the local economies in the Company’s diverse, geographic market areas.</span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Commercial</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">. Commercial loans consist of loans to commercial customers for use in financing working capital needs, equipment purchases and business expansions. The loans in this category are repaid primarily from the cash flow of a borrower’s principal business operation. Credit risk in these loans is driven by creditworthiness of a borrower and the economic conditions that impact the cash flow stability from business operations across the Company’s diverse, geographic market areas.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Home Equity</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">. Home equity loans consist of junior lien mortgages and first and junior lien lines of credit (revolving open-end and amortizing closed-end) secured by owner-occupied 1-4 family residences. Repayment of these loans is primarily dependent on the personal income and credit rating of the borrowers. Credit risk in these loans is impacted by economic conditions within the Company’s market areas that affect the value of the residential property securing the loans and affect the borrowers' personal incomes. Mitigating risk factors for this loan segment are a large number of borrowers, geographic dispersion of market areas and the loans are originated for terms that range from 10 to 15 years.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Other Consumer</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">. The other consumer loan portfolio consists of various short-term loans such as automobile loans and loans for other personal purposes. Repayment of these loans is primarily dependent on the personal income of the borrowers. Credit risk is driven by consumer economic factors (such as unemployment and general economic conditions in the Company’s diverse, geographic market area) and the creditworthiness of a borrower. </span></div><div><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The allowance is impacted by loan volumes, delinquency status, credit ratings, historical loss experiences, estimated prepayment speeds, weighted average lives and other conditions influencing loss expectations, such as reasonable and supportable forecasts of economic conditions. The methodology for estimating the amount of expected credit losses reported in the allowance has two basic components: 1) individual loans that do not share similar risk characteristics with other loans and the measurement of expected credit losses for such individual loans; and 2) the expected credit losses for pools of loans that share similar risk characteristics.</span></div><div><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Loans that do not Share Similar Risk Characteristics with Other Loans. </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">For a loan that does not share similar risk characteristics with other loans, expected credit loss is measured based on the net realizable value, that is, the difference between the discounted value of the expected future cash flows, based on the original effective interest rate, and the amortized cost basis of the loan. For these loans, the expected credit loss is equal to the amount by which the net realizable value of the loan is less than the amortized cost basis of the loan (which is net of previous charge-offs and deferred loan fees and costs), except when the loan is collateral-dependent, that is, when foreclosure is probable or the borrower is experiencing financial difficulty and repayment is expected to be provided substantially through the operation or sale of the collateral. In these cases, expected credit loss is measured as the difference between the amortized cost basis of the loan and the fair value of the collateral. The fair value of the collateral is adjusted for the estimated cost to sell if repayment or satisfaction of a loan is dependent on the sale (rather than only on the operation) of the collateral. The Company has determined that non-accrual loans do not share similar risk characteristics with other loans and these loans are individually evaluated for estimated allowance for credit losses. The Company, through its credit monitoring process, may also identify other loans that do no share similar risk characteristics and individually evaluate such loans. The starting point for determining the fair value of collateral is to obtain external appraisals or evaluations (new or updated). The valuation techniques used in preparing appraisals or evaluations (new or updated) include the cost approach, income approach, sales comparison approach, or a combination of the preceding valuation techniques. The Company’s credit department reviews appraisals, giving consideration to the highest and best use of the collateral. The appraisals or evaluations (new or updated) are reviewed at least quarterly and more frequently based on current market conditions, including deterioration in a borrower’s financial condition and when property values may be subject to significant volatility. Adjustments may be made to the fair value of the collateral after review and acceptance of the collateral appraisal or evaluation (new or updated).</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Loans that Share Similar Risk Characteristics with other Loans. </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">For estimating the allowance for loans that share similar risk characteristics with other loans, such loans are segregated into loan segments. Loans are designated into loan segments based on loans pooled by product types and similar risk characteristics or areas of risk concentration. In determining the ACL, the Company derives an estimated credit loss assumption from a model that categorizes loan pools based on loan type which is further segregated by the credit quality indicators. This model calculates an expected loss percentage for each loan segment by considering the non-discounted simple annual average historical loss rate of each loan segment (calculated through an “open pool” method), multiplying the loss rate by the amortized loan balance and incorporating that segment’s internally generated prepayment speed assumption and contractually scheduled remaining principal pay downs on a loan level basis. The annual historical loss rates are adjusted over a reasonable economic forecast period by a multiplier that is calculated based upon current national economic forecasts as a proportion of each segment’s historical average loss levels. The Company will then revert from the economic forecast period back to the historical average loss rate in a straight-line basis. After the reversion period, the loans will be assumed to experience their historical loss rate for the remainder of their contractual lives. The model applies the </span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">expected loss rate over the projected cash flows at the individual loan level and then aggregates the losses by loan segment in determining their quantitative allowance. The Company will also include qualitative adjustments to adjust the ACL on loan segments</span><span style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> to the extent the current or future market conditions are believed to vary substantially from historical conditions in regards to:</span></div><div style="margin-top:6pt;padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;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="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">i</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">nternational, national, regional and local economic business conditions and developments that affect the collectability of the portfolio, including the condition of various markets;</span></div><div style="padding-left:36pt;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">the nature and volume of the loan portfolio including the terms of the loans;</span></div><div style="padding-left:36pt;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">the experience, ability, and depth of the lending management and other relevant staff;</span></div><div style="padding-left:36pt;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">the volume and severity of past due and adversely classified or graded loans and the volume of non-accrual loans;</span></div><div style="padding-left:36pt;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">the quality of our loan review system;</span></div><div style="padding-left:36pt;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">the value of underlying collateral for collateralized loans;</span></div><div style="padding-left:36pt;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">the existence and effect of any concentrations of credit, and changes in the level of concentrations; and</span></div><div style="padding-left:36pt;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">the effect of external factors such as competition and legal and regulatory requirements on the level of estimated credit losses in the existing portfolio. </span></div><div><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The Company regularly reviews loans in the portfolio to assess credit quality indicators and to determine the appropriate loan classification and grading in accordance with applicable bank regulations. The primary credit quality indicator for residential, home equity and other consumer loans is the days past due status, which consists of the following categories: 1) performing loans; 2) 30 to 89 days past due loans; and 3) non-accrual and ninety days or more past due loans. The primary credit quality indicator for commercial real estate and commercial loans is the Company’s internal risk rating system, which includes the following categories: 1) pass loans; 2) special mention loans; 3) substandard loans; and 4) doubtful or loss loans. Such credit quality indicators are regularly monitored and incorporated into the Company’s allowance estimate. The following paragraphs further define the internal risk ratings for commercial real estate and commercial loans. </span></div><div><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Pass Loans.</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> These ratings represent loans that are of acceptable, good or excellent quality with very limited to no risk. Loans that do not have one of the following ratings are considered pass loans. </span></div><div><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Special Mention Loans.</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> These ratings represent loans that are designated as special mention per the regulatory definition. Special mention loans are currently protected but are potentially weak. The credit risk may be relatively minor yet constitute an undue and unwarranted risk in light of the circumstances surrounding a specific loan. The rating may be used to identify credit with potential weaknesses that if not corrected may weaken the loan to the point of inadequately protecting the Bank’s credit position. Examples include a lack of supervision, inadequate loan agreement, condition, or control of collateral, incomplete, or improper documentation, deviations from lending policy, and adverse trends in operations or economic conditions.</span></div><div><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Substandard Loans. </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> This rating represents loans that are inadequately protected by the current sound worth and paying capacity of the obligor or of the collateral pledged. A loan so classified must have a well-defined weakness that jeopardizes the liquidation of the debt. These loans are characterized by the distinct possibility that the Bank will sustain some loss if the deficiencies are not corrected. Loss potential, while existing in the aggregated amount of substandard loans, does not have to exist in an individual loan classified substandard.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Doubtful/Loss Loans. </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> A loan classified as doubtful has the characteristics that make collection in full, on the basis of currently existing facts, conditions, and values, highly improbable. The possibility of loss is extremely high, but because of pending factors, which may work to the advantage and strengthening of the loan, its classification as loss is deferred until its more exact status may be determined. Pending factors include proposed merger, acquisition, or liquidation procedures, capital injection, perfecting liens on additional collateral and refinancing plans. Loans are classified as loss when they are deemed to be not collectible and of such little value that continuance as an active asset of the Bank is not warranted. Loans classified as loss must be charged-off. Assignment of this classification does not mean that an asset has absolutely no recovery or salvage value, but that it is not practical or desirable to defer writing off a basically worthless asset, even though partial recovery may be attained in the future.</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;text-decoration:underline">Restructured Loans</span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">A restructured loan is considered a troubled debt restructuring (“TDR”) if the creditor, for economic or legal reasons related to the debtor’s financial difficulties, grants a concession to the debtor that it would not otherwise consider. The Company periodically enters into restructure agreements with borrowers whereby the loans were previously identified as TDRs. When such circumstances occur, the Company carefully evaluates the facts of the subsequent restructure to determine the appropriate accounting and under certain circumstances it may be acceptable not to account for the subsequently restructured loan as a TDR. When assessing whether a concession has been granted by the Company, any prior forgiveness on a cumulative basis is considered a continuing concession. The Company has made the following types of loan modifications, some of which were considered a TDR:</span></div><div style="margin-top:6pt;padding-left:36pt;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">reduction of the stated interest rate for the remaining term of the debt;</span></div><div style="padding-left:36pt;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">extension of the maturity date(s) at a stated rate of interest lower than the current market rate for newly originated debt having similar risk characteristics; and</span></div><div style="padding-left:36pt;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">reduction of the face amount of the debt as stated in the debt agreements.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The Company recognizes that while borrowers may experience deterioration in their financial condition, many continue to be creditworthy borrowers who have the willingness and capacity for debt repayment. In determining whether non-restructured or performing loans issued to a single or related party group of borrowers should continue to accrue interest when the borrower has other loans that are non-performing or are TDRs, the Company on a quarterly or more frequent basis performs an updated and comprehensive assessment of the willingness and capacity of the borrowers to timely and ultimately repay their total debt obligations, including contingent obligations. Such analysis takes into account current financial information about the borrowers and financially responsible guarantors, if any, including for example:</span></div><div style="margin-top:6pt;padding-left:36pt;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">analysis of global, i.e., aggregate debt service for total debt obligations;</span></div><div style="padding-left:36pt;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">assessment of the value and security protection of collateral pledged using current market conditions and alternative market assumptions across a variety of potential future situations; and</span></div><div style="padding-left:36pt;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">loan structures and related covenants.</span></div><div style="padding-left:36pt"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was signed into law which includes many provisions that impact the Company and its customers. The banking regulatory agencies have encouraged banks to work with borrowers who have been impacted by the coronavirus disease of 2019 (“COVID-19”) and the CARES Act, along with related regulatory guidance, allows banks to not designate certain modifications as TDRs that otherwise may have been classified as TDRs. In general, in order to qualify for such treatment, the modifications need to be short-term and made on a good faith basis in response to the COVID-19 pandemic to borrowers who were previously deemed current as outlined in the regulatory guidance. The Company has made such modifications to assist borrowers impacted by the COVID-19 pandemic. </span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The allowance for credit losses on a TDR is measured using the same method as all other loans held for investment. For a TDR that is individually reviewed and not collateral-dependent, the value of the concession can only be measured using the discounted cash flow method. When the value of a </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">concession is measured using the discounted cash flow method, the ACL is determined by discounting the expected future cash flows at the original interest of the loan.</span></div><div style="text-align:justify"><span><br/></span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;text-decoration:underline">Allowance for Credit Losses - Off-Balance Sheet Credit Exposures</span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The Company maintains a separate allowance for off-balance sheet credit exposures, including unfunded loan commitments, which is included in other liabilities on the Company’s statements of financial condition. The Company estimates the amount of expected losses by calculating a commitment usage factor over the contractual period for exposures and applying the loss factors used in the allowance for credit loss methodology to the results of the usage calculation to estimate the liability for credit losses related to unfunded commitments for each loan segment. No credit loss estimate is reported for off-balance sheet credit exposures that are unconditionally cancellable by the Bank or for unfunded amounts under such arrangements that may be drawn prior to the cancellation of the arrangement. </span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;text-decoration:underline">Provision for Credit Losses</span></div>The Company recognizes provision for credit losses on the allowance for off-balance sheet credit exposures (e.g., unfunded loan commitments) together with provision for credit losses on the loan portfolio in the income statement line item provision for credit losses.
CY2021Q1	gbci	Financing Receivable Allowance For Credit Losses Forecasting Period FinancingReceivableAllowanceForCreditLossesForecastingPeriod	4	quarter
CY2021Q1	gbci	Financing Receivable Allowance For Credit Losses Forecasting Period FinancingReceivableAllowanceForCreditLossesForecastingPeriod	4	quarter
CY2021Q1	gbci	Financing Receivable Allowance For Credit Losses Number Of Components FinancingReceivableAllowanceForCreditLossesNumberOfComponents	2	component
CY2021Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	489000	USD
CY2020Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	22744000	USD
CY2021Q1	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	441000	USD
CY2020Q1	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	3559000	USD
CY2021Q1	gbci	Maximum Term Leases Will Be Considered Short Term MaximumTermLeasesWillBeConsideredShortTerm	P12M
CY2021Q1	gbci	Maximum Period Up To Which Purchase Price Of Business Is Allocated To Assets Acquired And Liabilities Assumed MaximumPeriodUpToWhichPurchasePriceOfBusinessIsAllocatedToAssetsAcquiredAndLiabilitiesAssumed	P1Y
CY2021Q1	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	13695000	USD
CY2020Q1	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	14458000	USD
CY2020Q4	us-gaap	Capitalized Contract Cost Accumulated Impairment CapitalizedContractCostAccumulatedImpairment	0	USD
CY2021Q1	us-gaap	Capitalized Contract Cost Accumulated Impairment CapitalizedContractCostAccumulatedImpairment	0	USD
CY2021Q1	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	5750190000	USD
CY2021Q1	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	131176000	USD
CY2021Q1	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	28051000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	5853315000	USD
CY2021Q1	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	588751000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	10937000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	728000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	598960000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	5145866000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	192740000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	792000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	5337814000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	189836000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	13380000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	0	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	203216000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	91067000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	92128000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	711001000	USD
CY2021Q1	us-gaap	Heldtomaturity Securities Debt Maturities Next Rolling Twelve Months Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCost	482000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Debt Maturities Next Rolling Twelve Months Fair Value HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	486000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis	237676000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	248388000	USD
CY2021Q1	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Two Through Five Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCost	23431000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Two Through Five Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	24883000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis	247854000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	257032000	USD
CY2021Q1	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCost	66883000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Six Through Ten Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	71375000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis	658242000	USD
CY2020Q1	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	962000	USD
CY2021Q1	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	43000	USD
CY2020Q1	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	100000	USD
CY2021Q1	gbci	Heldto Maturity Securities Gross Realized Gains Losses Sale Proceeds HeldtoMaturitySecuritiesGrossRealizedGainsLossesSaleProceeds	4130000	USD
CY2020Q1	gbci	Heldto Maturity Securities Gross Realized Gains Losses Sale Proceeds HeldtoMaturitySecuritiesGrossRealizedGainsLossesSaleProceeds	20250000	USD
CY2021Q1	gbci	Heldto Maturity Securities Sold Security Realized Gain HeldtoMaturitySecuritiesSoldSecurityRealizedGain	0	USD
CY2020Q1	gbci	Heldto Maturity Securities Sold Security Realized Gain HeldtoMaturitySecuritiesSoldSecurityRealizedGain	1000	USD
CY2021Q1	gbci	Heldto Maturity Securities Sold Security Realized Loss HeldtoMaturitySecuritiesSoldSecurityRealizedLoss	42000	USD
CY2020Q1	gbci	Heldto Maturity Securities Sold Security Realized Loss HeldtoMaturitySecuritiesSoldSecurityRealizedLoss	0	USD
CY2021Q1	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	175	security
CY2021Q1	us-gaap	Heldtomaturity Securities Debt Maturities Rolling After Ten Years Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost	497955000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Debt Maturities Rolling After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue	502216000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	1234839000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate	1308549000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Amortized Cost Basis HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	588751000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue	598960000	USD
CY2021Q1	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	5750190000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	5853315000	USD
CY2021Q1	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	588751000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	598960000	USD
CY2021Q1	gbci	Proceeds From Sales And Calls Of Debt Securities Available For Sale ProceedsFromSalesAndCallsOfDebtSecuritiesAvailableForSale	54336000	USD
CY2020Q1	gbci	Proceeds From Sales And Calls Of Debt Securities Available For Sale ProceedsFromSalesAndCallsOfDebtSecuritiesAvailableForSale	77073000	USD
CY2021Q1	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	369000	USD
CY2021Q1	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	2454519000	USD
CY2021Q1	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	27870000	USD
CY2021Q1	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	3204000	USD
CY2021Q1	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	181000	USD
CY2021Q1	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	2457723000	USD
CY2021Q1	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	28051000	USD
CY2021Q1	gbci	Debt Securities Held To Maturity Unrealized Loss Position Number Of Positions DebtSecuritiesHeldToMaturityUnrealizedLossPositionNumberOfPositions	65	security
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	217131000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	728000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	0	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	0	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue	217131000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	728000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	46	security
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	145530000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	783000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	753000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	9000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	146283000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	792000	USD
CY2021Q1	gbci	Available For Sale Securities In Unrealized Loss Positions Severity Rate AvailableForSaleSecuritiesInUnrealizedLossPositionsSeverityRate	0.05
CY2021Q1	gbci	Number Of Credit Rating Categories Highest NumberOfCreditRatingCategoriesHighest	4	security
CY2020Q4	gbci	Debt Securities Available For Sale Past Due DebtSecuritiesAvailableForSalePastDue	0	USD
CY2021Q1	gbci	Debt Securities Available For Sale Past Due DebtSecuritiesAvailableForSalePastDue	0	USD
CY2021Q1	gbci	Interest Receivable Available For Sale Debt Securities InterestReceivableAvailableForSaleDebtSecurities	22398000	USD
CY2020Q4	gbci	Interest Receivable Available For Sale Debt Securities InterestReceivableAvailableForSaleDebtSecurities	20215000	USD
CY2021Q1	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2021Q1	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	588751000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	189836000	USD
CY2021Q1	gbci	Number Of Credit Rating Categories Highest NumberOfCreditRatingCategoriesHighest	4	security
CY2020Q4	us-gaap	Debt Securities Held To Maturity Past Due DebtSecuritiesHeldToMaturityPastDue	0	USD
CY2021Q1	us-gaap	Debt Securities Held To Maturity Past Due DebtSecuritiesHeldToMaturityPastDue	0	USD
CY2021Q1	gbci	Interest Receivable Held To Maturity Debt Securities InterestReceivableHeldToMaturityDebtSecurities	5929000	USD
CY2020Q4	gbci	Interest Receivable Held To Maturity Debt Securities InterestReceivableHeldToMaturityDebtSecurities	1728000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	0	USD
CY2021Q1	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	0	USD
CY2021Q1	us-gaap	Notes Receivable Gross NotesReceivableGross	11269929000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	11122696000	USD
CY2021Q1	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	156446000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	158243000	USD
CY2021Q1	us-gaap	Notes Receivable Net NotesReceivableNet	11113483000	USD
CY2020Q4	us-gaap	Notes Receivable Net NotesReceivableNet	10964453000	USD
CY2020Q1	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	2567000	USD
CY2021Q1	gbci	Unamortized Loan Origination Fees And Costs UnamortizedLoanOriginationFeesAndCosts	-37946000	USD
CY2020Q4	gbci	Unamortized Loan Origination Fees And Costs UnamortizedLoanOriginationFeesAndCosts	-26709000	USD
CY2021Q1	gbci	Unamortized Discounts And Premiums On Loans UnamortizedDiscountsAndPremiumsOnLoans	-15122000	USD
CY2020Q4	gbci	Unamortized Discounts And Premiums On Loans UnamortizedDiscountsAndPremiumsOnLoans	-17091000	USD
CY2021Q1	gbci	Interest Receivable Financing Receivable InterestReceivableFinancingReceivable	50989000	USD
CY2020Q4	gbci	Interest Receivable Financing Receivable InterestReceivableFinancingReceivable	53538000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	158243000	USD
CY2021Q1	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	489000	USD
CY2021Q1	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	4246000	USD
CY2021Q1	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	1960000	USD
CY2021Q1	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	156446000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	124490000	USD
CY2020Q1	us-gaap	Financing Receivable Change In Method Credit Loss Expense Reversal FinancingReceivableChangeInMethodCreditLossExpenseReversal	3720000	USD
CY2020Q1	us-gaap	Financing Receivable Allowance For Credit Loss Purchased With Credit Deterioration Increase FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease	49000	USD
CY2020Q1	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	22744000	USD
CY2020Q1	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	1754000	USD
CY2020Q1	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	150190000	USD
CY2021Q1	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	28654000	USD
CY2021Q1	gbci	Financing Receivable Nonaccrual With Allowance FinancingReceivableNonaccrualWithAllowance	1233000	USD
CY2021Q1	gbci	Financing Receivable Recorded Investment Past Due And Non Accrual Loans FinancingReceivableRecordedInvestmentPastDueAndNonAccrualLoans	78236000	USD
CY2021Q1	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	11191693000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	11269929000	USD
CY2020Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	29532000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	2432000	USD
CY2020Q4	gbci	Financing Receivable Recorded Investment Past Due And Non Accrual Loans FinancingReceivableRecordedInvestmentPastDueAndNonAccrualLoans	56410000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	11066286000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	11122696000	USD
CY2021Q1	gbci	Financing Receivable Nonaccrual Interest Income Reversed FinancingReceivableNonaccrualInterestIncomeReversed	73000	USD
CY2021Q1	gbci	Collateral Dependent Loans CollateralDependentLoans	86015000	USD
CY2020Q4	gbci	Collateral Dependent Loans CollateralDependentLoans	64455000	USD
CY2021Q1	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	7	Loan
CY2021Q1	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	1753000	USD
CY2021Q1	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	1753000	USD
CY2021Q1	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	Loan
CY2021Q1	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
CY2020Q1	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	5	Loan
CY2020Q1	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	7268000	USD
CY2020Q1	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	7268000	USD
CY2020Q1	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	Loan
CY2020Q1	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
CY2021Q1	gbci	Tdr With Pre Modification Loan Balance For Which Oreo Was Received TDRWithPreModificationLoanBalanceForWhichOreoWasReceived	1474000	USD
CY2020Q1	gbci	Tdr With Pre Modification Loan Balance For Which Oreo Was Received TDRWithPreModificationLoanBalanceForWhichOreoWasReceived	568000	USD
CY2021Q1	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	505000	USD
CY2020Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	548000	USD
CY2021Q1	gbci	Real Estate Acquired Through Foreclosure Securedby Residential Real Estate RealEstateAcquiredThroughForeclosureSecuredbyResidentialRealEstate	930000	USD
CY2020Q4	gbci	Real Estate Acquired Through Foreclosure Securedby Residential Real Estate RealEstateAcquiredThroughForeclosureSecuredbyResidentialRealEstate	273000	USD
CY2021Q1	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	5999000	USD
CY2020Q4	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	5999000	USD
CY2021Q1	us-gaap	Finance Lease Right Of Use Asset Accumulated Amortization FinanceLeaseRightOfUseAssetAccumulatedAmortization	334000	USD
CY2020Q4	us-gaap	Finance Lease Right Of Use Asset Accumulated Amortization FinanceLeaseRightOfUseAssetAccumulatedAmortization	273000	USD
CY2021Q1	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	5665000	USD
CY2021Q1	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	46298000	USD
CY2020Q4	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	5726000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	46820000	USD
CY2021Q1	us-gaap	Finance Lease Liability FinanceLeaseLiability	5864000	USD
CY2020Q1	us-gaap	Short Term Lease Cost ShortTermLeaseCost	90000	USD
CY2021Q1	us-gaap	Operating Lease Liability OperatingLeaseLiability	49250000	USD
CY2020Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	5891000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	49675000	USD
CY2021Q1	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P24Y
CY2021Q1	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P17Y
CY2020Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P24Y
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P17Y
CY2021Q1	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.026
CY2021Q1	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.034
CY2020Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.026
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.034
CY2021Q1	us-gaap	Finance Lease Liability Payments Due In Next Rolling Twelve Months FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths	261000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due Next Rolling Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths	4808000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due In Rolling Year Two FinanceLeaseLiabilityPaymentsDueInRollingYearTwo	268000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Two LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo	4424000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due In Rolling Year Three FinanceLeaseLiabilityPaymentsDueInRollingYearThree	274000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Three LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree	3955000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due In Rolling Year Four FinanceLeaseLiabilityPaymentsDueInRollingYearFour	281000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Four LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour	3978000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due In Rolling Year Five FinanceLeaseLiabilityPaymentsDueInRollingYearFive	287000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Five LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive	3898000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due In Rolling After Year Five FinanceLeaseLiabilityPaymentsDueInRollingAfterYearFive	6663000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due After Rolling Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterRollingYearFive	46484000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	8034000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	67547000	USD
CY2021Q1	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	112000	USD
CY2021Q1	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	3211000	USD
CY2021Q1	us-gaap	Finance Lease Liability Noncurrent FinanceLeaseLiabilityNoncurrent	5752000	USD
CY2021Q1	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	46039000	USD
CY2021Q1	us-gaap	Finance Lease Liability FinanceLeaseLiability	5864000	USD
CY2021Q1	us-gaap	Operating Lease Liability OperatingLeaseLiability	49250000	USD
CY2021Q1	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	2170000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	18297000	USD
CY2021Q1	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	61000	USD
CY2020Q1	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	57000	USD
CY2021Q1	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	37000	USD
CY2020Q1	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	41000	USD
CY2021Q1	us-gaap	Operating Lease Cost OperatingLeaseCost	1279000	USD
CY2020Q1	us-gaap	Operating Lease Cost OperatingLeaseCost	1108000	USD
CY2021Q1	us-gaap	Short Term Lease Cost ShortTermLeaseCost	86000	USD
CY2021Q1	us-gaap	Variable Lease Cost VariableLeaseCost	261000	USD
CY2020Q1	us-gaap	Variable Lease Cost VariableLeaseCost	385000	USD
CY2021Q1	us-gaap	Sublease Income SubleaseIncome	11000	USD
CY2020Q1	us-gaap	Sublease Income SubleaseIncome	2000	USD
CY2021Q1	us-gaap	Lease Cost LeaseCost	1713000	USD
CY2020Q1	us-gaap	Lease Cost LeaseCost	1679000	USD
CY2021Q1	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	37000	USD
CY2021Q1	us-gaap	Operating Lease Payments OperatingLeasePayments	780000	USD
CY2020Q1	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	41000	USD
CY2020Q1	us-gaap	Operating Lease Payments OperatingLeasePayments	615000	USD
CY2021Q1	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	27000	USD
CY2020Q1	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	23000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	514013000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	456418000	USD
CY2021Q1	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	0	USD
CY2020Q1	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	56937000	USD
CY2021Q1	us-gaap	Goodwill Goodwill	514013000	USD
CY2020Q1	us-gaap	Goodwill Goodwill	513355000	USD
CY2020Q4	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	40159000	USD
CY2021Q1	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	40159000	USD
CY2020Q4	us-gaap	Servicing Asset At Amortized Value ServicingAssetAtAmortizedValue	8976000	USD
CY2019Q4	us-gaap	Servicing Asset At Amortized Value ServicingAssetAtAmortizedValue	1618000	USD
CY2021Q1	us-gaap	Servicing Asset At Amortized Value Additions ServicingAssetAtAmortizedValueAdditions	1357000	USD
CY2020Q1	us-gaap	Servicing Asset At Amortized Value Additions ServicingAssetAtAmortizedValueAdditions	8298000	USD
CY2021Q1	us-gaap	Servicing Asset At Amortized Value Amortization1 ServicingAssetAtAmortizedValueAmortization1	397000	USD
CY2020Q1	us-gaap	Servicing Asset At Amortized Value Amortization1 ServicingAssetAtAmortizedValueAmortization1	940000	USD
CY2021Q1	us-gaap	Servicing Asset At Amortized Value ServicingAssetAtAmortizedValue	9936000	USD
CY2020Q4	us-gaap	Servicing Asset At Amortized Value ServicingAssetAtAmortizedValue	8976000	USD
CY2021Q1	us-gaap	Servicing Asset ServicingAsset	1377187000	USD
CY2020Q4	us-gaap	Servicing Asset ServicingAsset	1269080000	USD
CY2021Q1	us-gaap	Servicing Asset At Fair Value Amount ServicingAssetAtFairValueAmount	14263000	USD
CY2020Q4	us-gaap	Servicing Asset At Fair Value Amount ServicingAssetAtFairValueAmount	12087000	USD
CY2021Q1	us-gaap	Affordable Housing Project Investment Write Down Amount AffordableHousingProjectInvestmentWriteDownAmount	0	USD
CY2020Q1	us-gaap	Affordable Housing Project Investment Write Down Amount AffordableHousingProjectInvestmentWriteDownAmount	0	USD
CY2021Q1	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	2326000	USD
CY2020Q1	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	1842000	USD
CY2021Q1	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	3095000	USD
CY2020Q1	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	2485000	USD
CY2021Q1	us-gaap	Pledged Financial Instruments Not Separately Reported Securities For Repurchase Agreements PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForRepurchaseAgreements	1154580000	USD
CY2020Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities For Repurchase Agreements PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForRepurchaseAgreements	1151264000	USD
CY2021Q1	gbci	Consulting Fees ConsultingFees	2171000	USD
CY2020Q1	gbci	Consulting Fees ConsultingFees	2235000	USD
CY2021Q1	gbci	Loan Related Expenses LoanRelatedExpenses	1624000	USD
CY2020Q1	gbci	Loan Related Expenses LoanRelatedExpenses	864000	USD
CY2021Q1	gbci	Vie Write Downs Losses And Other Expenses VIEWriteDownsLossesAndOtherExpenses	1531000	USD
CY2020Q1	gbci	Vie Write Downs Losses And Other Expenses VIEWriteDownsLossesAndOtherExpenses	841000	USD
CY2021Q1	gbci	Telephone Expenses TelephoneExpenses	1375000	USD
CY2020Q1	gbci	Telephone Expenses TelephoneExpenses	1238000	USD
CY2021Q1	gbci	Debit Card Expense DebitCardExpense	1322000	USD
CY2020Q1	gbci	Debit Card Expense DebitCardExpense	1093000	USD
CY2021Q1	us-gaap	Postage Expense PostageExpense	961000	USD
CY2020Q1	us-gaap	Postage Expense PostageExpense	795000	USD
CY2021Q1	us-gaap	Business Development BusinessDevelopment	822000	USD
CY2020Q1	us-gaap	Business Development BusinessDevelopment	1048000	USD
CY2021Q1	us-gaap	Supplies Expense SuppliesExpense	790000	USD
CY2020Q1	us-gaap	Supplies Expense SuppliesExpense	903000	USD
CY2021Q1	gbci	Accounting Fees AccountingFees	455000	USD
CY2020Q1	gbci	Accounting Fees AccountingFees	448000	USD
CY2021Q1	gbci	Miscellaneous Employee Expenses MiscellaneousEmployeeExpenses	431000	USD
CY2020Q1	gbci	Miscellaneous Employee Expenses MiscellaneousEmployeeExpenses	1043000	USD
CY2021Q1	gbci	Deposit Related Expenses DepositRelatedExpenses	156000	USD
CY2020Q1	gbci	Deposit Related Expenses DepositRelatedExpenses	357000	USD
CY2021Q1	us-gaap	Legal Fees LegalFees	156000	USD
CY2020Q1	us-gaap	Legal Fees LegalFees	433000	USD
CY2021Q1	us-gaap	Business Combination Integration Related Costs BusinessCombinationIntegrationRelatedCosts	104000	USD
CY2020Q1	us-gaap	Business Combination Integration Related Costs BusinessCombinationIntegrationRelatedCosts	2791000	USD
CY2021Q1	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	748000	USD
CY2020Q1	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	1015000	USD
CY2021Q1	us-gaap	Other Noninterest Expense OtherNoninterestExpense	12646000	USD
CY2020Q1	us-gaap	Other Noninterest Expense OtherNoninterestExpense	15104000	USD
CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	80802000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	43339000	USD
CY2021Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	95465801	shares
CY2020Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	93287670	shares
CY2021Q1	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	81121	shares
CY2020Q1	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	72122	shares
CY2021Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	95546922	shares
CY2020Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	93359792	shares
CY2021Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.85
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.46
CY2021Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.85
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.46
CY2021Q1	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	0	shares
CY2020Q1	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	102094	shares
CY2021Q1	gbci	Fair Value Measurement Transfers From One Level To Another FairValueMeasurementTransfersFromOneLevelToAnother	0	USD
CY2020Q1	gbci	Fair Value Measurement Transfers From One Level To Another FairValueMeasurementTransfersFromOneLevelToAnother	0	USD

Files In Submission

Name	View Source	Status
gbci-20210331_pre.xml	Edgar Link	unprocessable
0000868671-21-000046-index-headers.html	Edgar Link	pending
0000868671-21-000046-index.html	Edgar Link	pending
0000868671-21-000046.txt	Edgar Link	pending
0000868671-21-000046-xbrl.zip	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
gbci-03312021xex311.htm	Edgar Link	pending
gbci-03312021xex312.htm	Edgar Link	pending
gbci-03312021xex32.htm	Edgar Link	pending
gbci-20210331.htm	Edgar Link	pending
gbci-20210331.xsd	Edgar Link	pending
gbci-20210331_cal.xml	Edgar Link	unprocessable
gbci-20210331_def.xml	Edgar Link	unprocessable
gbci-20210331_htm.xml	Edgar Link	completed
gbci-20210331_lab.xml	Edgar Link	unprocessable
MetaLinks.json	Edgar Link	pending
R1.htm	Edgar Link	pending
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report.css	Edgar Link	pending
Show.js	Edgar Link	pending

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$GBCI
GLACIER BANCORP, INC. Stock $gbci

2021 Q1 Form 10-Q Financial Statement

#000086867121000046 Filed on May 03, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$GBCI GLACIER BANCORP, INC. Stock $gbci

2021 Q1 Form 10-Q Financial Statement

#000086867121000046 Filed on May 03, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$GBCI
GLACIER BANCORP, INC. Stock $gbci