$GBCI
GLACIER BANCORP, INC. Stock $gbci

$gbci Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-Q Financial Statement

#000086867120000080 Filed on October 30, 2020

Income Statement

Concept	2020 Q4	2020 Q3	2019 Q3
Revenue	$171.3M	$157.5M	$142.4M
YoY Change	17.91%	10.6%	15.86%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$7.900M	$7.900M	$7.000M
YoY Change	5.33%	12.86%	22.81%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$5.550M	$6.084M	$10.95M
YoY Change	-37.17%	-44.42%	19.51%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$100.8M	$96.51M	$63.82M
YoY Change	44.81%	51.22%	6.13%
Income Tax	$18.95M	$18.75M	$12.21M
% Of Pretax Income	18.8%	19.43%	19.13%
Net Earnings	$81.86M	$77.76M	$51.61M
YoY Change	42.59%	50.66%	4.61%
Net Earnings / Revenue	47.79%	49.37%	36.24%
Basic Earnings Per Share	$0.86	$0.81	$0.57
Diluted Earnings Per Share	$0.86	$0.81	$0.57
COMMON SHARES
Basic Shares Outstanding	95.41M shares	95.41M shares	90.29M shares
Diluted Shares Outstanding		95.44M shares	90.45M shares

Balance Sheet

Concept	2020 Q4	2020 Q3	2019 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$633.1M	$769.9M	$406.4M
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	$272.8M	$326.9M	$307.6M
YoY Change	3.63%	6.29%	28.7%
Goodwill	$514.0M	$514.0M	$456.4M
YoY Change	12.62%	12.62%	57.64%
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets		$0.00	$0.00
YoY Change			-100.0%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$18.50B	$17.93B	$13.72B
YoY Change	35.23%	30.67%	15.2%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$3.000M	$4.000M	$4.000M
YoY Change	-40.0%	0.0%	0.0%
Accrued Expenses	$50.00M	$50.00M	$44.00M
YoY Change	13.64%	13.64%
Deferred Revenue
YoY Change
Short-Term Debt	$1.005B	$966.0M	$559.0M
YoY Change	76.32%	72.81%	36.67%
Long-Term Debt Due	$0.00	$0.00	$0.00
YoY Change
Total Short-Term Liabilities	$53.00M	$54.00M	$48.00M
YoY Change	8.16%	12.5%	1100.0%
LONG-TERM LIABILITIES
Long-Term Debt	$173.0M	$173.0M	$155.0M
YoY Change	2.37%	11.61%	7.64%
Other Long-Term Liabilities	$145.0M	$154.0M	$126.0M
YoY Change	19.83%	22.22%	22.33%
Total Long-Term Liabilities	$318.0M	$327.0M	$281.0M
YoY Change	9.66%	16.37%	13.77%
TOTAL LIABILITIES
Total Short-Term Liabilities	$53.00M	$54.00M	$48.00M
Total Long-Term Liabilities	$318.0M	$327.0M	$281.0M
Total Liabilities	$16.20B	$15.67B	$11.77B
YoY Change	38.16%	33.2%	12.95%
SHAREHOLDERS EQUITY
Retained Earnings	$667.9M	$629.1M	$528.6M
YoY Change	23.45%	19.01%	12.22%
Common Stock	$1.495B	$1.494B	$1.376B
YoY Change	8.45%	8.59%	30.97%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$2.307B	$2.255B	$1.953B
YoY Change
Total Liabilities & Shareholders Equity	$18.50B	$17.93B	$13.72B
YoY Change	35.23%	30.67%	15.2%

Cashflow Statement

Concept	2020 Q4	2020 Q3	2019 Q3
OPERATING ACTIVITIES
Net Income	$81.86M	$77.76M	$51.61M
YoY Change	42.59%	50.66%	4.61%
Depreciation, Depletion And Amortization	$7.900M	$7.900M	$7.000M
YoY Change	5.33%	12.86%	22.81%
Cash From Operating Activities	$75.70M	-$23.40M	$28.70M
YoY Change	-32.53%	-181.53%	-57.98%
INVESTING ACTIVITIES
Capital Expenditures	-$3.600M	-$3.200M	-$2.300M
YoY Change	63.64%	39.13%	-14.81%
Acquisitions
YoY Change
Other Investing Activities	-$681.3M	-$696.1M	$130.7M
YoY Change	604.55%	-632.59%	-246.52%
Cash From Investing Activities	-$684.9M	-$699.3M	$128.3M
YoY Change	592.52%	-645.05%	-239.61%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	472.3M	945.0M	18.10M
YoY Change	-631.87%	5120.99%	-148.53%
NET CHANGE
Cash From Operating Activities	75.70M	-23.40M	28.70M
Cash From Investing Activities	-684.9M	-699.3M	128.3M
Cash From Financing Activities	472.3M	945.0M	18.10M
Net Change In Cash	-136.9M	222.3M	175.1M
YoY Change	81.32%	26.96%	-387.52%
FREE CASH FLOW
Cash From Operating Activities	$75.70M	-$23.40M	$28.70M
Capital Expenditures	-$3.600M	-$3.200M	-$2.300M
Free Cash Flow	$79.30M	-$20.20M	$31.00M
YoY Change	-30.68%	-165.16%	-56.34%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Entity Central Index Key EntityCentralIndexKey	0000868671
	dei	Amendment Flag AmendmentFlag	false
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	us-gaap	Accounting Standards Update Extensible List AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201613Member
	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	1	operating_segment
	dei	Document Type DocumentType	10-Q
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2020-09-30
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity File Number EntityFileNumber	000-18911
	dei	Entity Registrant Name EntityRegistrantName	GLACIER BANCORP, INC.
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	MT
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	81-0519541
	dei	Entity Address Address Line1 EntityAddressAddressLine1	49 Commons Loop
	dei	Entity Address City Or Town EntityAddressCityOrTown	Kalispell,
	dei	Entity Address State Or Province EntityAddressStateOrProvince	MT
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	59901
	dei	City Area Code CityAreaCode	(406)
	dei	Local Phone Number LocalPhoneNumber	756-4200
	dei	Security12b Title Security12bTitle	Common Stock, $0.01 par value
	dei	Trading Symbol TradingSymbol	GBCI
	dei	Security Exchange Name SecurityExchangeName	NASDAQ
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
	dei	Entity Small Business EntitySmallBusiness	false
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Shell Company EntityShellCompany	false
CY2020Q4	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	95414850	shares
CY2020Q3	us-gaap	Cash And Due From Banks CashAndDueFromBanks	249245000	USD
CY2019Q4	us-gaap	Cash And Due From Banks CashAndDueFromBanks	198639000	USD
CY2020Q3	us-gaap	Federal Funds Sold FederalFundsSold	590000	USD
CY2019Q4	us-gaap	Federal Funds Sold FederalFundsSold	0	USD
CY2020Q3	us-gaap	Interest Bearing Deposits In Banks InterestBearingDepositsInBanks	520044000	USD
CY2019Q4	us-gaap	Interest Bearing Deposits In Banks InterestBearingDepositsInBanks	132322000	USD
CY2020Q3	us-gaap	Cash Cash Equivalents And Federal Funds Sold CashCashEquivalentsAndFederalFundsSold	769879000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents And Federal Funds Sold CashCashEquivalentsAndFederalFundsSold	330961000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	4125548000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2575252000	USD
CY2020Q3	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	193509000	USD
CY2019Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	224611000	USD
CY2020Q3	us-gaap	Debt Securities DebtSecurities	4319057000	USD
CY2019Q4	us-gaap	Debt Securities DebtSecurities	2799863000	USD
CY2020Q3	us-gaap	Loans Receivable Held For Sale Net Not Part Of Disposal Group LoansReceivableHeldForSaleNetNotPartOfDisposalGroup	147937000	USD
CY2019Q4	us-gaap	Loans Receivable Held For Sale Net Not Part Of Disposal Group LoansReceivableHeldForSaleNetNotPartOfDisposalGroup	69194000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	11618731000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	9512810000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	164552000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	124490000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	11454179000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	9388320000	USD
CY2020Q3	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	326925000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	310309000	USD
CY2020Q3	us-gaap	Other Real Estate And Foreclosed Assets OtherRealEstateAndForeclosedAssets	5361000	USD
CY2019Q4	us-gaap	Other Real Estate And Foreclosed Assets OtherRealEstateAndForeclosedAssets	5142000	USD
CY2020Q3	us-gaap	Interest Receivable InterestReceivable	91393000	USD
CY2019Q4	us-gaap	Interest Receivable InterestReceivable	56047000	USD
CY2020Q3	us-gaap	Deferred Income Tax Assets Net DeferredIncomeTaxAssetsNet	0	USD
CY2019Q4	us-gaap	Deferred Income Tax Assets Net DeferredIncomeTaxAssetsNet	2037000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	58121000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	63286000	USD
CY2020Q3	us-gaap	Goodwill Goodwill	514013000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	456418000	USD
CY2020Q3	gbci	Nonmarketable Securities Equity Securities NonmarketableSecuritiesEquitySecurities	10366000	USD
CY2019Q4	gbci	Nonmarketable Securities Equity Securities NonmarketableSecuritiesEquitySecurities	11623000	USD
CY2020Q3	us-gaap	Bank Owned Life Insurance BankOwnedLifeInsurance	123095000	USD
CY2019Q4	us-gaap	Bank Owned Life Insurance BankOwnedLifeInsurance	109428000	USD
CY2020Q3	us-gaap	Other Assets OtherAssets	105741000	USD
CY2019Q4	us-gaap	Other Assets OtherAssets	81371000	USD
CY2020Q3	us-gaap	Assets Assets	17926067000	USD
CY2019Q4	us-gaap	Assets Assets	13683999000	USD
CY2020Q3	us-gaap	Noninterest Bearing Deposit Liabilities NoninterestBearingDepositLiabilities	5479311000	USD
CY2019Q4	us-gaap	Noninterest Bearing Deposit Liabilities NoninterestBearingDepositLiabilities	3696627000	USD
CY2020Q3	us-gaap	Interest Bearing Deposit Liabilities InterestBearingDepositLiabilities	8820577000	USD
CY2019Q4	us-gaap	Interest Bearing Deposit Liabilities InterestBearingDepositLiabilities	7079830000	USD
CY2020Q3	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	965668000	USD
CY2019Q4	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	569824000	USD
CY2020Q3	us-gaap	Advances From Federal Home Loan Banks AdvancesFromFederalHomeLoanBanks	7318000	USD
CY2019Q4	us-gaap	Advances From Federal Home Loan Banks AdvancesFromFederalHomeLoanBanks	38611000	USD
CY2020Q3	us-gaap	Other Borrowings OtherBorrowings	32967000	USD
CY2019Q4	us-gaap	Other Borrowings OtherBorrowings	28820000	USD
CY2020Q3	us-gaap	Subordinated Debt SubordinatedDebt	139918000	USD
CY2019Q4	us-gaap	Subordinated Debt SubordinatedDebt	139914000	USD
CY2020Q3	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	3951000	USD
CY2019Q4	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	4686000	USD
CY2020Q3	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	17227000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	0	USD
CY2020Q3	us-gaap	Other Liabilities OtherLiabilities	204041000	USD
CY2019Q4	us-gaap	Other Liabilities OtherLiabilities	164954000	USD
CY2020Q3	us-gaap	Liabilities Liabilities	15670978000	USD
CY2019Q4	us-gaap	Liabilities Liabilities	11723266000	USD
CY2020Q3	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2019Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2020Q3	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2019Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2019Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	1000000	shares
CY2020Q3	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	1000000	shares
CY2019Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2020Q3	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2020Q3	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2019Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2020Q3	us-gaap	Preferred Stock Value PreferredStockValue	0	USD
CY2019Q4	us-gaap	Preferred Stock Value PreferredStockValue	0	USD
CY2019Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2020Q3	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2020Q3	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	117187500	shares
CY2019Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	117187500	shares
CY2020Q3	us-gaap	Common Stock Value Outstanding CommonStockValueOutstanding	954000	USD
CY2019Q4	us-gaap	Common Stock Value Outstanding CommonStockValueOutstanding	923000	USD
CY2020Q3	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	1493928000	USD
CY2019Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	1378534000	USD
CY2020Q3	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	629109000	USD
CY2019Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	541050000	USD
CY2020Q3	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	131098000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	40226000	USD
CY2020Q3	us-gaap	Stockholders Equity StockholdersEquity	2255089000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	1960733000	USD
CY2020Q3	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	17926067000	USD
CY2019Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	13683999000	USD
CY2020Q3	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	95413743	shares
CY2019Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	92289750	shares
CY2020Q3	us-gaap	Interest And Dividend Income Securities InterestAndDividendIncomeSecurities	25381000	USD
CY2019Q3	us-gaap	Interest And Dividend Income Securities InterestAndDividendIncomeSecurities	21357000	USD
	us-gaap	Interest And Dividend Income Securities InterestAndDividendIncomeSecurities	72228000	USD
	us-gaap	Interest And Dividend Income Securities InterestAndDividendIncomeSecurities	64600000	USD
CY2020Q3	us-gaap	Interest And Fee Income Loans Consumer Real Estate InterestAndFeeIncomeLoansConsumerRealEstate	11592000	USD
CY2019Q3	us-gaap	Interest And Fee Income Loans Consumer Real Estate InterestAndFeeIncomeLoansConsumerRealEstate	12156000	USD
	us-gaap	Interest And Fee Income Loans Consumer Real Estate InterestAndFeeIncomeLoansConsumerRealEstate	35216000	USD
	us-gaap	Interest And Fee Income Loans Consumer Real Estate InterestAndFeeIncomeLoansConsumerRealEstate	34345000	USD
CY2020Q3	us-gaap	Interest And Fee Income Loans Commercial InterestAndFeeIncomeLoansCommercial	109514000	USD
CY2019Q3	us-gaap	Interest And Fee Income Loans Commercial InterestAndFeeIncomeLoansCommercial	97224000	USD
	us-gaap	Interest And Fee Income Loans Commercial InterestAndFeeIncomeLoansCommercial	314541000	USD
	us-gaap	Interest And Fee Income Loans Commercial InterestAndFeeIncomeLoansCommercial	268806000	USD
CY2020Q3	us-gaap	Interest And Fee Income Loans Other Consumer InterestAndFeeIncomeLoansOtherConsumer	11000000	USD
CY2019Q3	us-gaap	Interest And Fee Income Loans Other Consumer InterestAndFeeIncomeLoansOtherConsumer	11658000	USD
	us-gaap	Interest And Fee Income Loans Other Consumer InterestAndFeeIncomeLoansOtherConsumer	33771000	USD
	us-gaap	Interest And Fee Income Loans Other Consumer InterestAndFeeIncomeLoansOtherConsumer	33145000	USD
CY2020Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	157487000	USD
CY2019Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	142395000	USD
	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	455756000	USD
	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	400896000	USD
CY2020Q3	us-gaap	Interest Expense Deposits InterestExpenseDeposits	3952000	USD
CY2019Q3	us-gaap	Interest Expense Deposits InterestExpenseDeposits	6214000	USD
	us-gaap	Interest Expense Deposits InterestExpenseDeposits	14120000	USD
	us-gaap	Interest Expense Deposits InterestExpenseDeposits	17179000	USD
CY2020Q3	us-gaap	Interest Expense Securities Sold Under Agreements To Repurchase InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase	886000	USD
CY2019Q3	us-gaap	Interest Expense Securities Sold Under Agreements To Repurchase InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase	999000	USD
	us-gaap	Interest Expense Securities Sold Under Agreements To Repurchase InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase	2783000	USD
	us-gaap	Interest Expense Securities Sold Under Agreements To Repurchase InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase	2687000	USD
CY2020Q3	gbci	Interest Expense Federal Home Loan Bank Advance InterestExpenseFederalHomeLoanBankAdvance	70000	USD
CY2019Q3	gbci	Interest Expense Federal Home Loan Bank Advance InterestExpenseFederalHomeLoanBankAdvance	2035000	USD
	gbci	Interest Expense Federal Home Loan Bank Advance InterestExpenseFederalHomeLoanBankAdvance	684000	USD
	gbci	Interest Expense Federal Home Loan Bank Advance InterestExpenseFederalHomeLoanBankAdvance	8937000	USD
CY2020Q3	us-gaap	Interest Expense Other InterestExpenseOther	173000	USD
CY2019Q3	us-gaap	Interest Expense Other InterestExpenseOther	47000	USD
	us-gaap	Interest Expense Other InterestExpenseOther	473000	USD
	us-gaap	Interest Expense Other InterestExpenseOther	123000	USD
CY2020Q3	us-gaap	Interest Expense Junior Subordinated Debentures InterestExpenseJuniorSubordinatedDebentures	1003000	USD
CY2019Q3	us-gaap	Interest Expense Junior Subordinated Debentures InterestExpenseJuniorSubordinatedDebentures	1652000	USD
	us-gaap	Interest Expense Junior Subordinated Debentures InterestExpenseJuniorSubordinatedDebentures	3705000	USD
	us-gaap	Interest Expense Junior Subordinated Debentures InterestExpenseJuniorSubordinatedDebentures	5014000	USD
CY2020Q3	us-gaap	Interest Expense InterestExpense	6084000	USD
CY2019Q3	us-gaap	Interest Expense InterestExpense	10947000	USD
	us-gaap	Interest Expense InterestExpense	21765000	USD
	us-gaap	Interest Expense InterestExpense	33940000	USD
CY2020Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	151403000	USD
CY2019Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	131448000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	433991000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	366956000	USD
CY2020Q3	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	2869000	USD
CY2019Q3	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	0	USD
	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	39165000	USD
	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	57000	USD
CY2020Q3	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	148534000	USD
CY2019Q3	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	131448000	USD
	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	394826000	USD
	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	366899000	USD
CY2020Q3	gbci	Service Charges And Other Fees ServiceChargesAndOtherFees	13404000	USD
CY2019Q3	gbci	Service Charges And Other Fees ServiceChargesAndOtherFees	15138000	USD
	gbci	Service Charges And Other Fees ServiceChargesAndOtherFees	38790000	USD
	gbci	Service Charges And Other Fees ServiceChargesAndOtherFees	53178000	USD
CY2020Q3	gbci	Miscellaneous Loan Fees And Charges MiscellaneousLoanFeesAndCharges	2084000	USD
CY2019Q3	gbci	Miscellaneous Loan Fees And Charges MiscellaneousLoanFeesAndCharges	1775000	USD
	gbci	Miscellaneous Loan Fees And Charges MiscellaneousLoanFeesAndCharges	5051000	USD
	gbci	Miscellaneous Loan Fees And Charges MiscellaneousLoanFeesAndCharges	3934000	USD
CY2020Q3	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	35516000	USD
CY2019Q3	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	10369000	USD
	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	73236000	USD
	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	23929000	USD
CY2020Q3	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	24000	USD
CY2019Q3	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	13811000	USD
	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	1015000	USD
	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	14158000	USD
CY2020Q3	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	2639000	USD
CY2019Q3	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	1956000	USD
	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	10071000	USD
	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	7158000	USD
CY2020Q3	us-gaap	Noninterest Income NoninterestIncome	53667000	USD
CY2019Q3	us-gaap	Noninterest Income NoninterestIncome	43049000	USD
	us-gaap	Noninterest Income NoninterestIncome	128163000	USD
	us-gaap	Noninterest Income NoninterestIncome	102357000	USD
CY2020Q3	us-gaap	Labor And Related Expense LaborAndRelatedExpense	64866000	USD
CY2019Q3	us-gaap	Labor And Related Expense LaborAndRelatedExpense	62509000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	182507000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	167210000	USD
CY2020Q3	us-gaap	Occupancy Net OccupancyNet	9369000	USD
CY2019Q3	us-gaap	Occupancy Net OccupancyNet	8731000	USD
	us-gaap	Occupancy Net OccupancyNet	27945000	USD
	us-gaap	Occupancy Net OccupancyNet	25348000	USD
CY2020Q3	us-gaap	Advertising Expense AdvertisingExpense	2779000	USD
CY2019Q3	us-gaap	Advertising Expense AdvertisingExpense	2719000	USD
	us-gaap	Advertising Expense AdvertisingExpense	7404000	USD
	us-gaap	Advertising Expense AdvertisingExpense	7874000	USD
CY2020Q3	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	5597000	USD
CY2019Q3	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	4466000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	15921000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	12420000	USD
CY2020Q3	us-gaap	Foreclosed Real Estate Expense ForeclosedRealEstateExpense	186000	USD
CY2019Q3	us-gaap	Foreclosed Real Estate Expense ForeclosedRealEstateExpense	166000	USD
	us-gaap	Foreclosed Real Estate Expense ForeclosedRealEstateExpense	373000	USD
	us-gaap	Foreclosed Real Estate Expense ForeclosedRealEstateExpense	496000	USD
CY2020Q3	gbci	General Insurance And Federal Deposit Insurance Corporation Premium Expense GeneralInsuranceAndFederalDepositInsuranceCorporationPremiumExpense	1495000	USD
CY2019Q3	gbci	General Insurance And Federal Deposit Insurance Corporation Premium Expense GeneralInsuranceAndFederalDepositInsuranceCorporationPremiumExpense	593000	USD
	gbci	General Insurance And Federal Deposit Insurance Corporation Premium Expense GeneralInsuranceAndFederalDepositInsuranceCorporationPremiumExpense	3622000	USD
	gbci	General Insurance And Federal Deposit Insurance Corporation Premium Expense GeneralInsuranceAndFederalDepositInsuranceCorporationPremiumExpense	3726000	USD
CY2020Q3	gbci	Loss On Hedging Activity LossOnHedgingActivity	0	USD
CY2019Q3	gbci	Loss On Hedging Activity LossOnHedgingActivity	13528000	USD
	gbci	Loss On Hedging Activity LossOnHedgingActivity	0	USD
	gbci	Loss On Hedging Activity LossOnHedgingActivity	13528000	USD
CY2020Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2612000	USD
CY2019Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2360000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	7758000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	5919000	USD
CY2020Q3	us-gaap	Other Noninterest Expense OtherNoninterestExpense	18786000	USD
CY2019Q3	us-gaap	Other Noninterest Expense OtherNoninterestExpense	15603000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	50229000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	43154000	USD
CY2020Q3	us-gaap	Noninterest Expense NoninterestExpense	105690000	USD
CY2019Q3	us-gaap	Noninterest Expense NoninterestExpense	110675000	USD
	us-gaap	Noninterest Expense NoninterestExpense	295759000	USD
	us-gaap	Noninterest Expense NoninterestExpense	279675000	USD
CY2020Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	96511000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	63822000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	227230000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	189581000	USD
CY2020Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	18754000	USD
CY2019Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	12212000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	42690000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	36447000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	77757000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	51610000	USD
	us-gaap	Net Income Loss NetIncomeLoss	184540000	USD
	us-gaap	Net Income Loss NetIncomeLoss	153134000	USD
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.81
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.57
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.95
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.76
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.81
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.57
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.95
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.76
CY2020Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.30
CY2019Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.29
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.88
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.82
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	95411656	shares
CY2019Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	90294811	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	94704198	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	86911402	shares
CY2020Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	95442576	shares
CY2019Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	90449195	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	94747894	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	87082178	shares
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	77757000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	51610000	USD
	us-gaap	Net Income Loss NetIncomeLoss	184540000	USD
	us-gaap	Net Income Loss NetIncomeLoss	153134000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	1693000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	11113000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	123262000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	87442000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	24000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	13811000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	1014000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	14166000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	1669000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-2698000	USD
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	122248000	USD
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	73276000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	424000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-684000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	30979000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	18568000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	1245000	USD
	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	-135000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-2014000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	91269000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	54708000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-76000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-1393000	USD
	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-532000	USD
	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-7047000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	-10315000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	-10816000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-76000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	8922000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-532000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	3769000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	-20000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	2261000	USD
	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	955000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	-56000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	6661000	USD
	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	-397000	USD
	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	2814000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	1189000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	4647000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	90872000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	57522000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	78946000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	56257000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	275412000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	210656000	USD
CY2019Q2	us-gaap	Stockholders Equity StockholdersEquity	1687376000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	51610000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	4647000	USD
CY2019Q3	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	26784000	USD
CY2019Q3	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	229385000	USD
CY2019Q3	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
CY2019Q3	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7167000	USD
CY2019Q3	us-gaap	Stockholders Equity StockholdersEquity	1953401000	USD
CY2020Q2	us-gaap	Stockholders Equity StockholdersEquity	2203715000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	77757000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	1189000	USD
CY2020Q3	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	28683000	USD
CY2020Q3	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
CY2020Q3	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	1111000	USD
CY2020Q3	us-gaap	Stockholders Equity StockholdersEquity	2255089000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	1515854000	USD
	us-gaap	Net Income Loss NetIncomeLoss	153134000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	57522000	USD
	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	72260000	USD
	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	316538000	USD
	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	8071000	USD
CY2019Q3	us-gaap	Stockholders Equity StockholdersEquity	1953401000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	1960733000	USD
	us-gaap	Net Income Loss NetIncomeLoss	184540000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	90872000	USD
	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	84134000	USD
	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	112133000	USD
	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	3292000	USD
CY2020Q3	us-gaap	Stockholders Equity StockholdersEquity	2255089000	USD
	us-gaap	Net Income Loss NetIncomeLoss	184540000	USD
	us-gaap	Net Income Loss NetIncomeLoss	153134000	USD
	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	39165000	USD
	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	57000	USD
	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-10830000	USD
	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-11687000	USD
	gbci	Accretion Amortization Of Discounts And Premiums Business Combinations AccretionAmortizationOfDiscountsAndPremiumsBusinessCombinations	23369000	USD
	gbci	Accretion Amortization Of Discounts And Premiums Business Combinations AccretionAmortizationOfDiscountsAndPremiumsBusinessCombinations	2680000	USD
	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	0	USD
	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	4630000	USD
	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	1393224000	USD
	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	671038000	USD
	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	1400697000	USD
	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	633085000	USD
	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	73236000	USD
	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	23929000	USD
	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	1015000	USD
	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	14158000	USD
	us-gaap	Life Insurance Corporate Or Bank Owned Change In Value LifeInsuranceCorporateOrBankOwnedChangeInValue	2059000	USD
	us-gaap	Life Insurance Corporate Or Bank Owned Change In Value LifeInsuranceCorporateOrBankOwnedChangeInValue	1629000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	2829000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	6554000	USD
	us-gaap	Depreciation Nonproduction DepreciationNonproduction	15124000	USD
	us-gaap	Depreciation Nonproduction DepreciationNonproduction	13713000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	64000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	288000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	7758000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	5919000	USD
	gbci	Variable Interest Entities Investment Amortization VariableInterestEntitiesInvestmentAmortization	8244000	USD
	gbci	Variable Interest Entities Investment Amortization VariableInterestEntitiesInvestmentAmortization	6767000	USD
	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	33558000	USD
	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	5348000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	22729000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	367000	USD
	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-861000	USD
	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	61000	USD
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-5315000	USD
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-1730000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	113757000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	114440000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	711268000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	545191000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	457299000	USD
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	1839308000	USD
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	839835000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	29530000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	48940000	USD
	us-gaap	Proceeds From Loan And Lease Originations And Principal Collections1 ProceedsFromLoanAndLeaseOriginationsAndPrincipalCollections1	2978796000	USD
	us-gaap	Proceeds From Loan And Lease Originations And Principal Collections1 ProceedsFromLoanAndLeaseOriginationsAndPrincipalCollections1	2497073000	USD
	gbci	Payments For Loans Originated Or Acquired PaymentsForLoansOriginatedOrAcquired	4627653000	USD
	gbci	Payments For Loans Originated Or Acquired PaymentsForLoansOriginatedOrAcquired	2900692000	USD
	us-gaap	Payments For Proceeds From Productive Assets PaymentsForProceedsFromProductiveAssets	8140000	USD
	us-gaap	Payments For Proceeds From Productive Assets PaymentsForProceedsFromProductiveAssets	14230000	USD
	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	2140000	USD
	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	2960000	USD
	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	76275000	USD
	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	115436000	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	71397000	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	93397000	USD
	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	7975000	USD
	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	7956000	USD
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	-43713000	USD
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	-79334000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-2878828000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	56200000	USD
	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	2920429000	USD
	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	377986000	USD
	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	388595000	USD
	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	161191000	USD
	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	-30000000	USD
	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	-285000000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	30000000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	0	USD
	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	31271000	USD
	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	151073000	USD
	us-gaap	Proceeds From Repayments Of Other Debt ProceedsFromRepaymentsOfOtherDebt	463000	USD
	us-gaap	Proceeds From Repayments Of Other Debt ProceedsFromRepaymentsOfOtherDebt	97000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	73999000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	70970000	USD
	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	1023000	USD
	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	277000	USD
	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	795000	USD
	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	0	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	3203989000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	31954000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	438918000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	202594000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	330961000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	203790000	USD
CY2020Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	769879000	USD
CY2019Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	406384000	USD
	us-gaap	Interest Paid Net InterestPaidNet	22626000	USD
	us-gaap	Interest Paid Net InterestPaidNet	33878000	USD
	us-gaap	Income Taxes Paid IncomeTaxesPaid	43944000	USD
	us-gaap	Income Taxes Paid IncomeTaxesPaid	33032000	USD
	us-gaap	Transfer Of Other Real Estate TransferOfOtherRealEstate	215000	USD
	us-gaap	Transfer Of Other Real Estate TransferOfOtherRealEstate	7000	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	2062000	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	2347000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	7343000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	3910000	USD
	gbci	Dividends Declared But Not Paid During The Period DividendsDeclaredButNotPaidDuringThePeriod	28799000	USD
	gbci	Dividends Declared But Not Paid During The Period DividendsDeclaredButNotPaidDuringThePeriod	26874000	USD
	us-gaap	Stock Issued1 StockIssued1	112133000	USD
	us-gaap	Stock Issued1 StockIssued1	316538000	USD
	gbci	Cash Consideration For Outstanding Shares CashConsiderationForOutstandingShares	13721000	USD
	gbci	Cash Consideration For Outstanding Shares CashConsiderationForOutstandingShares	16424000	USD
	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	745420000	USD
	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	1190267000	USD
	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	619565000	USD
	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	1024141000	USD
CY2020Q3	gbci	Number Of Bank Divisions NumberOfBankDivisions	16	division
	gbci	Financing Receivable Allowance For Credit Losses Forecasting Period FinancingReceivableAllowanceForCreditLossesForecastingPeriod	4	quarter
	gbci	Financing Receivable Allowance For Credit Losses Forecasting Period FinancingReceivableAllowanceForCreditLossesForecastingPeriod	4	quarter
	gbci	Financing Receivable Allowance For Credit Losses Number Of Components FinancingReceivableAllowanceForCreditLossesNumberOfComponents	2	numberOfComponents
	gbci	Maximum Term Leases Will Be Considered Short Term MaximumTermLeasesWillBeConsideredShortTerm	P12M
	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	40184000	USD
	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	54608000	USD
CY2020Q3	us-gaap	Capitalized Contract Cost Accumulated Impairment CapitalizedContractCostAccumulatedImpairment	0	USD
CY2019Q4	us-gaap	Capitalized Contract Cost Accumulated Impairment CapitalizedContractCostAccumulatedImpairment	0	USD
CY2020Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	3949422000	USD
CY2020Q3	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	177137000	USD
CY2020Q3	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	1011000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	4125548000	USD
CY2020Q3	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	193509000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	13068000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	0	USD
CY2020Q3	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	206577000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2521374000	USD
CY2019Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	55965000	USD
CY2019Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	2087000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2575252000	USD
CY2019Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	224611000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	9785000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	0	USD
CY2019Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	234396000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	119874000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	121303000	USD
CY2020Q3	us-gaap	Heldtomaturity Securities Debt Maturities Next Rolling Twelve Months Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCost	0	USD
CY2020Q3	us-gaap	Held To Maturity Securities Debt Maturities Next Rolling Twelve Months Fair Value HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	0	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis	264927000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	277758000	USD
CY2020Q3	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Two Through Five Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCost	19543000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Two Through Five Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	20996000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis	263208000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	277022000	USD
CY2020Q3	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCost	69924000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Six Through Ten Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	75680000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis	942145000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	1010282000	USD
CY2020Q3	us-gaap	Heldtomaturity Securities Debt Maturities Rolling After Ten Years Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost	104042000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Debt Maturities Rolling After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue	109901000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	1590154000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate	1686365000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Amortized Cost Basis HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	193509000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue	206577000	USD
CY2020Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	3949422000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	4125548000	USD
CY2020Q3	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	193509000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	206577000	USD
CY2020Q3	gbci	Proceeds From Sales And Calls Of Debt Securities Available For Sale ProceedsFromSalesAndCallsOfDebtSecuritiesAvailableForSale	69304000	USD
CY2019Q3	gbci	Proceeds From Sales And Calls Of Debt Securities Available For Sale ProceedsFromSalesAndCallsOfDebtSecuritiesAvailableForSale	401701000	USD
	gbci	Proceeds From Sales And Calls Of Debt Securities Available For Sale ProceedsFromSalesAndCallsOfDebtSecuritiesAvailableForSale	184088000	USD
	gbci	Proceeds From Sales And Calls Of Debt Securities Available For Sale ProceedsFromSalesAndCallsOfDebtSecuritiesAvailableForSale	878072000	USD
CY2020Q3	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	102000	USD
CY2019Q3	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	14329000	USD
	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	1206000	USD
	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	18613000	USD
CY2020Q3	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	78000	USD
CY2019Q3	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	518000	USD
	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	192000	USD
	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	4447000	USD
CY2020Q3	gbci	Heldto Maturity Securities Gross Realized Gains Losses Sale Proceeds HeldtoMaturitySecuritiesGrossRealizedGainsLossesSaleProceeds	9280000	USD
CY2019Q3	gbci	Heldto Maturity Securities Gross Realized Gains Losses Sale Proceeds HeldtoMaturitySecuritiesGrossRealizedGainsLossesSaleProceeds	16365000	USD
	gbci	Heldto Maturity Securities Gross Realized Gains Losses Sale Proceeds HeldtoMaturitySecuritiesGrossRealizedGainsLossesSaleProceeds	29530000	USD
	gbci	Heldto Maturity Securities Gross Realized Gains Losses Sale Proceeds HeldtoMaturitySecuritiesGrossRealizedGainsLossesSaleProceeds	48940000	USD
CY2020Q3	gbci	Heldto Maturity Securities Sold Security Realized Gain HeldtoMaturitySecuritiesSoldSecurityRealizedGain	0	USD
CY2019Q3	gbci	Heldto Maturity Securities Sold Security Realized Gain HeldtoMaturitySecuritiesSoldSecurityRealizedGain	0	USD
	gbci	Heldto Maturity Securities Sold Security Realized Gain HeldtoMaturitySecuritiesSoldSecurityRealizedGain	1000	USD
	gbci	Heldto Maturity Securities Sold Security Realized Gain HeldtoMaturitySecuritiesSoldSecurityRealizedGain	2000	USD
CY2020Q3	gbci	Heldto Maturity Securities Sold Security Realized Loss HeldtoMaturitySecuritiesSoldSecurityRealizedLoss	0	USD
CY2019Q3	gbci	Heldto Maturity Securities Sold Security Realized Loss HeldtoMaturitySecuritiesSoldSecurityRealizedLoss	0	USD
	gbci	Heldto Maturity Securities Sold Security Realized Loss HeldtoMaturitySecuritiesSoldSecurityRealizedLoss	0	USD
	gbci	Heldto Maturity Securities Sold Security Realized Loss HeldtoMaturitySecuritiesSoldSecurityRealizedLoss	10000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	690000	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	65	security
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	324015000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	1002000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	9000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	324705000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	1011000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	88	security
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	289499000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	1608000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	46637000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	479000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	336136000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	2087000	USD
	gbci	Available For Sale Securities In Unrealized Loss Positions Severity Rate AvailableForSaleSecuritiesInUnrealizedLossPositionsSeverityRate	0.05
CY2020Q3	gbci	Number Of Credit Rating Categories Highest NumberOfCreditRatingCategoriesHighest	4	security
CY2020Q3	gbci	Debt Securities Available For Sale Past Due DebtSecuritiesAvailableForSalePastDue	0	USD
CY2020Q3	gbci	Interest Receivable Available For Sale Debt Securities InterestReceivableAvailableForSaleDebtSecurities	23491000	USD
	us-gaap	Debt Securities Available For Sale Purchased With Credit Deterioration Amount At Par Value DebtSecuritiesAvailableForSalePurchasedWithCreditDeteriorationAmountAtParValue	0	USD
	us-gaap	Debt Securities Available For Sale Purchased With Credit Deterioration Allowance For Credit Loss At Acquisition Date DebtSecuritiesAvailableForSalePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate	0	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2020Q3	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	193509000	USD
CY2019Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	224611000	USD
CY2020Q3	gbci	Number Of Credit Rating Categories Highest NumberOfCreditRatingCategoriesHighest	4	security
CY2020Q3	us-gaap	Debt Securities Held To Maturity Past Due DebtSecuritiesHeldToMaturityPastDue	0	USD
CY2020Q3	gbci	Interest Receivable Held To Maturity Debt Securities InterestReceivableHeldToMaturityDebtSecurities	2079000	USD
CY2020Q3	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	0	USD
CY2020Q3	us-gaap	Notes Receivable Gross NotesReceivableGross	11618731000	USD
CY2019Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	9512810000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	164552000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	124490000	USD
CY2020Q3	us-gaap	Notes Receivable Net NotesReceivableNet	11454179000	USD
CY2019Q4	us-gaap	Notes Receivable Net NotesReceivableNet	9388320000	USD
CY2020Q3	gbci	Unamortized Loan Origination Fees And Costs UnamortizedLoanOriginationFeesAndCosts	-38712000	USD
CY2019Q4	gbci	Unamortized Loan Origination Fees And Costs UnamortizedLoanOriginationFeesAndCosts	-6964000	USD
CY2020Q3	gbci	Unamortized Discounts And Premiums On Loans UnamortizedDiscountsAndPremiumsOnLoans	-18063000	USD
CY2019Q4	gbci	Unamortized Discounts And Premiums On Loans UnamortizedDiscountsAndPremiumsOnLoans	-21574000	USD
CY2020Q3	gbci	Interest Receivable Financing Receivable InterestReceivableFinancingReceivable	65806000	USD
CY2019Q4	gbci	Interest Receivable Financing Receivable InterestReceivableFinancingReceivable	40962000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	162509000	USD
CY2020Q3	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	2869000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	2630000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	1804000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	164552000	USD
CY2019Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	129054000	USD
CY2019Q3	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0	USD
CY2019Q3	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	5890000	USD
CY2019Q3	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	2371000	USD
CY2019Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	125535000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	124490000	USD
	us-gaap	Financing Receivable Change In Method Credit Loss Expense Reversal FinancingReceivableChangeInMethodCreditLossExpenseReversal	3720000	USD
	us-gaap	Financing Receivable Allowance For Credit Loss Purchased With Credit Deterioration Increase FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease	49000	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	39165000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	7865000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	4993000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	164552000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	131239000	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	57000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	12090000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	6329000	USD
CY2019Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	125535000	USD
	us-gaap	Financing Receivable Purchased With Credit Deterioration Amount At Par Value FinancingReceivablePurchasedWithCreditDeteriorationAmountAtParValue	3401000	USD
	us-gaap	Financing Receivable Purchased With Credit Deterioration Allowance For Credit Loss At Acquisition Date FinancingReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate	49000	USD
	us-gaap	Financing Receivable Purchased With Credit Deterioration Discount Premium FinancingReceivablePurchasedWithCreditDeteriorationDiscountPremium	13000	USD
CY2020Q3	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	32047000	USD
CY2020Q3	gbci	Financing Receivable Nonaccrual With Allowance FinancingReceivableNonaccrualWithAllowance	4303000	USD
CY2020Q3	gbci	Financing Receivable Recorded Investment Past Due And Non Accrual Loans FinancingReceivableRecordedInvestmentPastDueAndNonAccrualLoans	56933000	USD
CY2020Q3	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	11561798000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	11618731000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	30883000	USD
CY2019Q4	gbci	Financing Receivable Recorded Investment Past Due And Non Accrual Loans FinancingReceivableRecordedInvestmentPastDueAndNonAccrualLoans	55487000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	9457323000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	9512810000	USD
	gbci	Financing Receivable Nonaccrual Interest Income Reversed FinancingReceivableNonaccrualInterestIncomeReversed	628000	USD
CY2020Q3	gbci	Collateral Dependent Loans CollateralDependentLoans	22985000	USD
CY2020Q3	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	6	Loan
CY2020Q3	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	7482000	USD
CY2020Q3	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	7482000	USD
CY2020Q3	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	Loan
CY2020Q3	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
CY2019Q3	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	6	Loan
CY2019Q3	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	3168000	USD
CY2019Q3	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	3168000	USD
CY2019Q3	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	Loan
CY2019Q3	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	16	Loan
	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	14945000	USD
	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	14945000	USD
	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	Loan
	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	14	Loan
	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	5261000	USD
	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	5247000	USD
	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	1	Loan
	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	305000	USD
CY2020Q3	gbci	Tdr With Pre Modification Loan Balance For Which Oreo Was Received TDRWithPreModificationLoanBalanceForWhichOreoWasReceived	2265000	USD
CY2019Q3	gbci	Tdr With Pre Modification Loan Balance For Which Oreo Was Received TDRWithPreModificationLoanBalanceForWhichOreoWasReceived	2982000	USD
CY2020Q3	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	765000	USD
CY2019Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	1744000	USD
CY2020Q3	gbci	Real Estate Acquired Through Foreclosure Securedby Residential Real Estate RealEstateAcquiredThroughForeclosureSecuredbyResidentialRealEstate	1917000	USD
CY2019Q4	gbci	Real Estate Acquired Through Foreclosure Securedby Residential Real Estate RealEstateAcquiredThroughForeclosureSecuredbyResidentialRealEstate	1504000	USD
CY2019Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	94504000	USD
CY2019Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	9418306000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	9512810000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	95000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	124395000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	124490000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With Related Allowance Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment	5388000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance	5388000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	95000	USD
CY2019	us-gaap	Impaired Financing Receivable With Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment	10378000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	89116000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance	99355000	USD
CY2019	us-gaap	Impaired Financing Receivable With No Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment	93338000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	94504000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	104743000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	95000	USD
CY2019	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	103716000	USD
CY2020Q3	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	5999000	USD
CY2019Q4	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	6537000	USD
CY2020Q3	us-gaap	Finance Lease Right Of Use Asset Accumulated Amortization FinanceLeaseRightOfUseAssetAccumulatedAmortization	212000	USD
CY2019Q4	us-gaap	Finance Lease Right Of Use Asset Accumulated Amortization FinanceLeaseRightOfUseAssetAccumulatedAmortization	917000	USD
CY2020Q3	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	5787000	USD
CY2020Q3	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	47329000	USD
CY2019Q4	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	5620000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	41453000	USD
CY2020Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	5917000	USD
CY2020Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	50089000	USD
CY2019Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	5671000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	43904000	USD
CY2020Q3	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P24Y
CY2020Q3	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P17Y
CY2019Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P24Y
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P19Y
CY2020Q3	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.026
CY2020Q3	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.035
CY2019Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.030
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.037
CY2020Q3	us-gaap	Finance Lease Liability Payments Due In Next Rolling Twelve Months FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths	259000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Four LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour	3914000	USD
CY2020Q3	us-gaap	Finance Lease Liability Payments Due In Rolling Year Five FinanceLeaseLiabilityPaymentsDueInRollingYearFive	285000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due Next Rolling Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths	4608000	USD
CY2020Q3	us-gaap	Finance Lease Liability Payments Due In Rolling Year Two FinanceLeaseLiabilityPaymentsDueInRollingYearTwo	265000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Two LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo	4431000	USD
CY2020Q3	us-gaap	Finance Lease Liability Payments Due In Rolling Year Three FinanceLeaseLiabilityPaymentsDueInRollingYearThree	270000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Three LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree	3961000	USD
CY2020Q3	us-gaap	Finance Lease Liability Payments Due In Rolling Year Four FinanceLeaseLiabilityPaymentsDueInRollingYearFour	277000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Five LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive	3869000	USD
CY2020Q3	us-gaap	Finance Lease Liability Payments Due In Rolling After Year Five FinanceLeaseLiabilityPaymentsDueInRollingAfterYearFive	6808000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due After Rolling Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterRollingYearFive	48432000	USD
CY2020Q3	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	8164000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	69215000	USD
CY2020Q3	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	214000	USD
CY2020Q3	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	2973000	USD
CY2020Q3	us-gaap	Finance Lease Liability Noncurrent FinanceLeaseLiabilityNoncurrent	5703000	USD
CY2020Q3	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	47116000	USD
CY2020Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	5917000	USD
CY2020Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	50089000	USD
CY2020Q3	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	2247000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	19126000	USD
CY2020Q3	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	59000	USD
CY2019Q3	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	16000	USD
	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	174000	USD
	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	48000	USD
CY2020Q3	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	40000	USD
CY2019Q3	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	2000	USD
	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	121000	USD
	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	6000	USD
CY2020Q3	us-gaap	Operating Lease Cost OperatingLeaseCost	1254000	USD
CY2019Q3	us-gaap	Operating Lease Cost OperatingLeaseCost	1057000	USD
	us-gaap	Operating Lease Cost OperatingLeaseCost	3553000	USD
	us-gaap	Operating Lease Cost OperatingLeaseCost	2967000	USD
CY2020Q3	us-gaap	Short Term Lease Cost ShortTermLeaseCost	88000	USD
CY2019Q3	us-gaap	Short Term Lease Cost ShortTermLeaseCost	102000	USD
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	266000	USD
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	330000	USD
CY2020Q3	us-gaap	Variable Lease Cost VariableLeaseCost	264000	USD
CY2019Q3	us-gaap	Variable Lease Cost VariableLeaseCost	236000	USD
	us-gaap	Variable Lease Cost VariableLeaseCost	977000	USD
	us-gaap	Variable Lease Cost VariableLeaseCost	657000	USD
CY2020Q3	us-gaap	Sublease Income SubleaseIncome	2000	USD
CY2019Q3	us-gaap	Sublease Income SubleaseIncome	2000	USD
	us-gaap	Sublease Income SubleaseIncome	5000	USD
	us-gaap	Sublease Income SubleaseIncome	5000	USD
CY2020Q3	us-gaap	Lease Cost LeaseCost	1703000	USD
CY2019Q3	us-gaap	Lease Cost LeaseCost	1411000	USD
	us-gaap	Lease Cost LeaseCost	5086000	USD
	us-gaap	Lease Cost LeaseCost	4003000	USD
CY2020Q3	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	40000	USD
CY2019Q3	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	21000	USD
CY2020Q3	us-gaap	Operating Lease Payments OperatingLeasePayments	706000	USD
CY2019Q3	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	2000	USD
CY2019Q3	us-gaap	Operating Lease Payments OperatingLeasePayments	565000	USD
CY2020Q3	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	23000	USD
	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	121000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	1994000	USD
	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	6000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	1541000	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	67000	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	63000	USD
CY2020Q2	us-gaap	Goodwill Goodwill	513355000	USD
CY2019Q2	us-gaap	Goodwill Goodwill	330887000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	456418000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	289586000	USD
CY2020Q3	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	658000	USD
CY2019Q3	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	125535000	USD
	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	57595000	USD
	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	166836000	USD
CY2020Q3	us-gaap	Goodwill Goodwill	514013000	USD
CY2019Q3	us-gaap	Goodwill Goodwill	456422000	USD
CY2020Q3	us-gaap	Goodwill Goodwill	514013000	USD
CY2019Q3	us-gaap	Goodwill Goodwill	456422000	USD
CY2020Q3	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	40159000	USD
CY2019Q4	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	40159000	USD
	us-gaap	Affordable Housing Project Investment Write Down Amount AffordableHousingProjectInvestmentWriteDownAmount	0	USD
	us-gaap	Affordable Housing Project Investment Write Down Amount AffordableHousingProjectInvestmentWriteDownAmount	0	USD
CY2020Q3	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	1936000	USD
CY2019Q3	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	1609000	USD
	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	5766000	USD
	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	4504000	USD
CY2020Q3	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	2608000	USD
CY2019Q3	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	2202000	USD
	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	7771000	USD
	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	6169000	USD
CY2020Q3	us-gaap	Pledged Financial Instruments Not Separately Reported Securities For Repurchase Agreements PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForRepurchaseAgreements	1096781000	USD
CY2019Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities For Repurchase Agreements PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForRepurchaseAgreements	711210000	USD
CY2020Q3	gbci	Consulting Fees ConsultingFees	4050000	USD
CY2019Q3	gbci	Consulting Fees ConsultingFees	1938000	USD
	gbci	Consulting Fees ConsultingFees	8604000	USD
	gbci	Consulting Fees ConsultingFees	5715000	USD
CY2020Q3	us-gaap	Business Combination Integration Related Costs BusinessCombinationIntegrationRelatedCosts	792000	USD
CY2019Q3	us-gaap	Business Combination Integration Related Costs BusinessCombinationIntegrationRelatedCosts	2058000	USD
	us-gaap	Business Combination Integration Related Costs BusinessCombinationIntegrationRelatedCosts	7311000	USD
	us-gaap	Business Combination Integration Related Costs BusinessCombinationIntegrationRelatedCosts	4103000	USD
CY2020Q3	gbci	Loan Related Expenses LoanRelatedExpenses	4060000	USD
CY2019Q3	gbci	Loan Related Expenses LoanRelatedExpenses	924000	USD
	gbci	Loan Related Expenses LoanRelatedExpenses	5867000	USD
	gbci	Loan Related Expenses LoanRelatedExpenses	2726000	USD
CY2020Q3	gbci	Telephone Expenses TelephoneExpenses	1314000	USD
CY2019Q3	gbci	Telephone Expenses TelephoneExpenses	1216000	USD
	gbci	Telephone Expenses TelephoneExpenses	3865000	USD
	gbci	Telephone Expenses TelephoneExpenses	3601000	USD
CY2020Q3	gbci	Debit Card Expense DebitCardExpense	1414000	USD
CY2019Q3	gbci	Debit Card Expense DebitCardExpense	1699000	USD
	gbci	Debit Card Expense DebitCardExpense	3704000	USD
	gbci	Debit Card Expense DebitCardExpense	5003000	USD
CY2020Q3	gbci	Vie Write Downs Losses And Other Expenses VIEWriteDownsLossesAndOtherExpenses	1510000	USD
CY2019Q3	gbci	Vie Write Downs Losses And Other Expenses VIEWriteDownsLossesAndOtherExpenses	1427000	USD
	gbci	Vie Write Downs Losses And Other Expenses VIEWriteDownsLossesAndOtherExpenses	3396000	USD
	gbci	Vie Write Downs Losses And Other Expenses VIEWriteDownsLossesAndOtherExpenses	2878000	USD
CY2020Q3	us-gaap	Business Development BusinessDevelopment	1139000	USD
CY2019Q3	us-gaap	Business Development BusinessDevelopment	1176000	USD
	us-gaap	Business Development BusinessDevelopment	3110000	USD
	us-gaap	Business Development BusinessDevelopment	3189000	USD
CY2020Q3	us-gaap	Supplies Expense SuppliesExpense	877000	USD
CY2019Q3	us-gaap	Supplies Expense SuppliesExpense	735000	USD
	us-gaap	Supplies Expense SuppliesExpense	2704000	USD
	us-gaap	Supplies Expense SuppliesExpense	2246000	USD
CY2020Q3	us-gaap	Postage Expense PostageExpense	851000	USD
CY2019Q3	us-gaap	Postage Expense PostageExpense	831000	USD
	us-gaap	Postage Expense PostageExpense	2479000	USD
	us-gaap	Postage Expense PostageExpense	2487000	USD
CY2020Q3	gbci	Miscellaneous Employee Expenses MiscellaneousEmployeeExpenses	560000	USD
CY2019Q3	gbci	Miscellaneous Employee Expenses MiscellaneousEmployeeExpenses	1245000	USD
	gbci	Miscellaneous Employee Expenses MiscellaneousEmployeeExpenses	2247000	USD
	gbci	Miscellaneous Employee Expenses MiscellaneousEmployeeExpenses	3646000	USD
CY2020Q3	gbci	Accounting Fees AccountingFees	455000	USD
CY2019Q3	gbci	Accounting Fees AccountingFees	365000	USD
	gbci	Accounting Fees AccountingFees	1453000	USD
	gbci	Accounting Fees AccountingFees	1290000	USD
CY2020Q3	gbci	Deposit Related Expenses DepositRelatedExpenses	355000	USD
CY2019Q3	gbci	Deposit Related Expenses DepositRelatedExpenses	361000	USD
	gbci	Deposit Related Expenses DepositRelatedExpenses	1263000	USD
	gbci	Deposit Related Expenses DepositRelatedExpenses	1353000	USD
CY2020Q3	us-gaap	Legal Fees LegalFees	206000	USD
CY2019Q3	us-gaap	Legal Fees LegalFees	338000	USD
	us-gaap	Legal Fees LegalFees	1025000	USD
	us-gaap	Legal Fees LegalFees	926000	USD
CY2020Q3	gbci	Atm Expenses ATMExpenses	245000	USD
CY2019Q3	gbci	Atm Expenses ATMExpenses	299000	USD
	gbci	Atm Expenses ATMExpenses	373000	USD
	gbci	Atm Expenses ATMExpenses	1312000	USD
CY2020Q3	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	958000	USD
CY2019Q3	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	991000	USD
	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	2828000	USD
	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	2679000	USD
CY2020Q3	us-gaap	Other Noninterest Expense OtherNoninterestExpense	18786000	USD
CY2019Q3	us-gaap	Other Noninterest Expense OtherNoninterestExpense	15603000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	50229000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	43154000	USD
	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	60023000	USD
	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	2501000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	57522000	USD
	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	91630000	USD
	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	758000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	90872000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	77757000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	51610000	USD
	us-gaap	Net Income Loss NetIncomeLoss	184540000	USD
	us-gaap	Net Income Loss NetIncomeLoss	153134000	USD
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	95411656	shares
CY2019Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	90294811	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	94704198	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	86911402	shares
CY2020Q3	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	30920	shares
CY2019Q3	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	154384	shares
	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	43696	shares
	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	170776	shares
CY2020Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	95442576	shares
CY2019Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	90449195	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	94747894	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	87082178	shares
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.81
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.57
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.95
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.76
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.81
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.57
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.95
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.76
CY2020Q3	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	93253	shares
CY2019Q3	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	4037	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	78605	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1360	shares
	gbci	Fair Value Measurement Transfers From One Level To Another FairValueMeasurementTransfersFromOneLevelToAnother	0	USD
	gbci	Fair Value Measurement Transfers From One Level To Another FairValueMeasurementTransfersFromOneLevelToAnother	0	USD

Files In Submission

Name	View Source	Status
0000868671-20-000080-index-headers.html	Edgar Link	pending
0000868671-20-000080-index.html	Edgar Link	pending
0000868671-20-000080.txt	Edgar Link	pending
0000868671-20-000080-xbrl.zip	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
gbci-09302020xex311.htm	Edgar Link	pending
gbci-09302020xex312.htm	Edgar Link	pending
gbci-09302020xex32.htm	Edgar Link	pending
gbci-20200930.htm	Edgar Link	pending
gbci-20200930.xsd	Edgar Link	pending
gbci-20200930_cal.xml	Edgar Link	unprocessable
gbci-20200930_def.xml	Edgar Link	unprocessable
gbci-20200930_htm.xml	Edgar Link	completed
gbci-20200930_lab.xml	Edgar Link	unprocessable
gbci-20200930_pre.xml	Edgar Link	unprocessable
MetaLinks.json	Edgar Link	pending
R1.htm	Edgar Link	pending
R10.htm	Edgar Link	pending
R11.htm	Edgar Link	pending
R12.htm	Edgar Link	pending
R13.htm	Edgar Link	pending
R14.htm	Edgar Link	pending
R15.htm	Edgar Link	pending
R16.htm	Edgar Link	pending
R17.htm	Edgar Link	pending
R18.htm	Edgar Link	pending
R19.htm	Edgar Link	pending
R2.htm	Edgar Link	pending
R20.htm	Edgar Link	pending
R21.htm	Edgar Link	pending
R22.htm	Edgar Link	pending
R23.htm	Edgar Link	pending
R24.htm	Edgar Link	pending
R25.htm	Edgar Link	pending
R26.htm	Edgar Link	pending
R27.htm	Edgar Link	pending
R28.htm	Edgar Link	pending
R29.htm	Edgar Link	pending
R3.htm	Edgar Link	pending
R30.htm	Edgar Link	pending
R31.htm	Edgar Link	pending
R32.htm	Edgar Link	pending
R33.htm	Edgar Link	pending
R34.htm	Edgar Link	pending
R35.htm	Edgar Link	pending
R36.htm	Edgar Link	pending
R37.htm	Edgar Link	pending
R38.htm	Edgar Link	pending
R39.htm	Edgar Link	pending
R4.htm	Edgar Link	pending
R40.htm	Edgar Link	pending
R41.htm	Edgar Link	pending
R42.htm	Edgar Link	pending
R43.htm	Edgar Link	pending
R44.htm	Edgar Link	pending
R45.htm	Edgar Link	pending
R46.htm	Edgar Link	pending
R47.htm	Edgar Link	pending
R48.htm	Edgar Link	pending
R49.htm	Edgar Link	pending
R5.htm	Edgar Link	pending
R50.htm	Edgar Link	pending
R51.htm	Edgar Link	pending
R52.htm	Edgar Link	pending
R53.htm	Edgar Link	pending
R54.htm	Edgar Link	pending
R55.htm	Edgar Link	pending
R56.htm	Edgar Link	pending
R57.htm	Edgar Link	pending
R58.htm	Edgar Link	pending
R59.htm	Edgar Link	pending
R6.htm	Edgar Link	pending
R60.htm	Edgar Link	pending
R61.htm	Edgar Link	pending
R62.htm	Edgar Link	pending
R63.htm	Edgar Link	pending
R64.htm	Edgar Link	pending
R65.htm	Edgar Link	pending
R66.htm	Edgar Link	pending
R67.htm	Edgar Link	pending
R68.htm	Edgar Link	pending
R69.htm	Edgar Link	pending
R7.htm	Edgar Link	pending
R70.htm	Edgar Link	pending
R71.htm	Edgar Link	pending
R72.htm	Edgar Link	pending
R73.htm	Edgar Link	pending
R74.htm	Edgar Link	pending
R75.htm	Edgar Link	pending
R76.htm	Edgar Link	pending
R8.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
report.css	Edgar Link	pending
Show.js	Edgar Link	pending

Create your account

Find Stocks Worth Researching

Deeply Understand Businesses

Value Businesses Intelligently

$GBCI
GLACIER BANCORP, INC. Stock $gbci

2020 Q4 Form 10-Q Financial Statement

#000086867120000080 Filed on October 30, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$GBCI GLACIER BANCORP, INC. Stock $gbci

2020 Q4 Form 10-Q Financial Statement

#000086867120000080 Filed on October 30, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$GBCI
GLACIER BANCORP, INC. Stock $gbci