$GBCI
GLACIER BANCORP, INC. Stock $gbci

$gbci Overview Financials Valuation SEC Filings Company Website

2019 Q4 Form 10-K Financial Statement

#000086867120000032 Filed on February 21, 2020

Income Statement

Concept	2019 Q4	2018 Q4	2018 Q3
Revenue	$145.3M	$125.3M	$122.9M
YoY Change	15.94%	29.32%	27.41%
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	$7.500M	$6.300M	$5.700M
YoY Change	19.05%	43.18%	29.55%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$8.833M	$9.436M	$9.160M
YoY Change	-6.39%	33.43%	19.71%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$69.61M	$61.25M	$60.14M
YoY Change	13.66%	32.33%	24.98%
Income Tax	$12.20M	$11.65M	$10.80M
% Of Pretax Income	17.53%	19.02%	17.96%
Net Earnings	$57.41M	$49.60M	$49.34M
YoY Change	15.75%	231.63%	35.24%
Net Earnings / Revenue	39.52%	39.58%	40.14%
Basic Earnings Per Share	$0.62	$0.59	$0.58
Diluted Earnings Per Share	$0.62	$0.59	$0.58
COMMON SHARES
Basic Shares Outstanding	92.19M shares	84.52M shares	84.52M shares
Diluted Shares Outstanding			84.59M shares

Balance Sheet

Concept	2019 Q4	2018 Q4	2018 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$331.0M	$203.8M	$307.1M
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	$263.2M	$241.5M	$239.0M
YoY Change	8.99%	36.19%	33.77%
Goodwill	$456.4M	$289.6M	$289.5M
YoY Change	57.61%	62.86%	62.83%
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets	$2.000M	$24.00M	$37.00M
YoY Change	-91.67%	-36.84%	-37.29%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$13.68B	$12.12B	$11.91B
YoY Change	12.95%	24.82%	21.54%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$5.000M	$4.000M	$4.000M
YoY Change	25.0%	33.33%	33.33%
Accrued Expenses	$44.00M
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$570.0M	$396.0M	$409.0M
YoY Change	43.94%	9.09%	-9.91%
Long-Term Debt Due	$0.00
YoY Change
Total Short-Term Liabilities	$49.00M	$4.000M	$4.000M
YoY Change	1125.0%	33.33%	33.33%
LONG-TERM LIABILITIES
Long-Term Debt	$169.0M	$149.0M	$144.0M
YoY Change	13.42%	11.19%	7.46%
Other Long-Term Liabilities	$121.0M	$117.0M	$103.0M
YoY Change	3.42%	60.27%	28.75%
Total Long-Term Liabilities	$290.0M	$266.0M	$247.0M
YoY Change	9.02%	28.5%	15.42%
TOTAL LIABILITIES
Total Short-Term Liabilities	$49.00M	$4.000M	$4.000M
Total Long-Term Liabilities	$290.0M	$266.0M	$247.0M
Total Liabilities	$11.72B	$10.60B	$10.42B
YoY Change	10.6%	24.59%	21.23%
SHAREHOLDERS EQUITY
Retained Earnings	$541.1M	$473.2M	$471.0M
YoY Change	14.34%	17.63%	16.77%
Common Stock	$1.379B	$1.051B	$1.050B
YoY Change	31.13%	31.74%	31.74%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$1.961B	$1.516B	$1.493B
YoY Change
Total Liabilities & Shareholders Equity	$13.68B	$12.12B	$11.91B
YoY Change	12.95%	24.82%	21.54%

Cashflow Statement

Concept	2019 Q4	2018 Q4	2018 Q3
OPERATING ACTIVITIES
Net Income	$57.41M	$49.60M	$49.34M
YoY Change	15.75%	231.63%	35.24%
Depreciation, Depletion And Amortization	$7.500M	$6.300M	$5.700M
YoY Change	19.05%	43.18%	29.55%
Cash From Operating Activities	$112.2M	$113.2M	$68.30M
YoY Change	-0.88%	48.56%	63.4%
INVESTING ACTIVITIES
Capital Expenditures	-$2.200M	-$4.600M	-$2.700M
YoY Change	-52.17%	91.67%	8.0%
Acquisitions
YoY Change
Other Investing Activities	-$96.70M	-$337.1M	-$89.20M
YoY Change	-71.31%	-37555.56%	-207.08%
Cash From Investing Activities	-$98.90M	-$341.7M	-$91.90M
YoY Change	-71.06%	22680.0%	-213.74%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-88.80M	125.2M	-37.30M
YoY Change	-170.93%	-231.93%	-73.36%
NET CHANGE
Cash From Operating Activities	112.2M	113.2M	68.30M
Cash From Investing Activities	-98.90M	-341.7M	-91.90M
Cash From Financing Activities	-88.80M	125.2M	-37.30M
Net Change In Cash	-75.50M	-103.3M	-60.90M
YoY Change	-26.91%	411.39%	250.0%
FREE CASH FLOW
Cash From Operating Activities	$112.2M	$113.2M	$68.30M
Capital Expenditures	-$2.200M	-$4.600M	-$2.700M
Free Cash Flow	$114.4M	$117.8M	$71.00M
YoY Change	-2.89%	49.87%	60.27%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
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CY2019	dei	Entity File Number EntityFileNumber	000-18911
CY2019	dei	Entity Registrant Name EntityRegistrantName	GLACIER BANCORP, INC.
CY2019	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	MT
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CY2019	dei	Security12b Title Security12bTitle	Common Stock, $0.01 par value
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CY2017	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	30439000	USD
CY2019	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	14415000	USD
CY2018	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	-1113000	USD
CY2017	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	-660000	USD
CY2019	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	9048000	USD
CY2018	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	11111000	USD
CY2017	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	10383000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	130774000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	118824000	USD
CY2017	us-gaap	Noninterest Income NoninterestIncome	112239000	USD
CY2019	us-gaap	Labor And Related Expense LaborAndRelatedExpense	222753000	USD
CY2018	us-gaap	Labor And Related Expense LaborAndRelatedExpense	195056000	USD
CY2017	us-gaap	Labor And Related Expense LaborAndRelatedExpense	160506000	USD
CY2019	us-gaap	Occupancy Net OccupancyNet	34497000	USD
CY2018	us-gaap	Occupancy Net OccupancyNet	30734000	USD
CY2017	us-gaap	Occupancy Net OccupancyNet	26631000	USD
CY2019	us-gaap	Advertising Expense AdvertisingExpense	10621000	USD
CY2018	us-gaap	Advertising Expense AdvertisingExpense	9566000	USD
CY2017	us-gaap	Advertising Expense AdvertisingExpense	8405000	USD
CY2019	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	17392000	USD
CY2018	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	15911000	USD
CY2017	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	14150000	USD
CY2019	us-gaap	Foreclosed Real Estate Expense ForeclosedRealEstateExpense	1105000	USD
CY2018	us-gaap	Foreclosed Real Estate Expense ForeclosedRealEstateExpense	3221000	USD
CY2017	us-gaap	Foreclosed Real Estate Expense ForeclosedRealEstateExpense	1909000	USD
CY2019	gbci	General Insuranceand Federal Deposit Insurance Corporation Premium Expense GeneralInsuranceandFederalDepositInsuranceCorporationPremiumExpense	3771000	USD
CY2018	gbci	General Insuranceand Federal Deposit Insurance Corporation Premium Expense GeneralInsuranceandFederalDepositInsuranceCorporationPremiumExpense	5075000	USD
CY2017	gbci	General Insuranceand Federal Deposit Insurance Corporation Premium Expense GeneralInsuranceandFederalDepositInsuranceCorporationPremiumExpense	4431000	USD
CY2019	gbci	Loss On Hedging Activity LossOnHedgingActivity	13528000	USD
CY2018	gbci	Loss On Hedging Activity LossOnHedgingActivity	0	USD
CY2017	gbci	Loss On Hedging Activity LossOnHedgingActivity	0	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	8485000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	6270000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2494000	USD
CY2019	us-gaap	Other Noninterest Expense OtherNoninterestExpense	62775000	USD
CY2018	us-gaap	Other Noninterest Expense OtherNoninterestExpense	54294000	USD
CY2017	us-gaap	Other Noninterest Expense OtherNoninterestExpense	47045000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	374927000	USD
CY2018	us-gaap	Noninterest Expense NoninterestExpense	320127000	USD
CY2017	us-gaap	Noninterest Expense NoninterestExpense	265571000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	259194000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	222209000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	181002000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	48650000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	40331000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	64625000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	210544000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	181878000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	116377000	USD
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.39
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.18
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.50
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.38
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.17
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.50
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.31
CY2018	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.31
CY2017	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.14
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	88255290	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	83603515	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	77537664	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	88385775	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	83677185	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	77607605	shares
CY2019	us-gaap	Net Income Loss NetIncomeLoss	210544000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	181878000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	116377000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	77158000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-15608000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	3428000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	14423000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-12000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-636000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	62735000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-15596000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	4064000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	15896000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-3952000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	1563000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	46839000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-11644000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	2501000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-7047000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	3286000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	444000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	-10816000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	-2334000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	-4892000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	3769000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	5620000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	5336000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	955000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	1424000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	2083000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	2814000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	4196000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	3253000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	49653000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-7448000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	5754000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	260197000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	174430000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	122131000	USD
CY2016Q4	us-gaap	Stockholders Equity StockholdersEquity	1116869000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	116377000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	5754000	USD
CY2017	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	88848000	USD
CY2017	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	46673000	USD
CY2017	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
CY2017	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	2232000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	1199057000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	181878000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-7448000	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	110954000	USD
CY2018	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	250807000	USD
CY2018	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
CY2018	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	2514000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	1515854000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	210544000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	49653000	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	117563000	USD
CY2019	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	316538000	USD
CY2019	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	10821000	USD
CY2019Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	-25114000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	1960733000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	210544000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	181878000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	116377000	USD
CY2019	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	57000	USD
CY2018	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	9953000	USD
CY2017	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	10824000	USD
CY2019	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-12985000	USD
CY2018	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-13095000	USD
CY2017	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-20026000	USD
CY2019	gbci	Accretion Amortizationof Discountsand Premiums Business Combinations AccretionAmortizationofDiscountsandPremiumsBusinessCombinations	3712000	USD
CY2018	gbci	Accretion Amortizationof Discountsand Premiums Business Combinations AccretionAmortizationofDiscountsandPremiumsBusinessCombinations	3963000	USD
CY2017	gbci	Accretion Amortizationof Discountsand Premiums Business Combinations AccretionAmortizationofDiscountsandPremiumsBusinessCombinations	5131000	USD
CY2019	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	4630000	USD
CY2018	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	1649000	USD
CY2017	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	471000	USD
CY2019	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	983988000	USD
CY2018	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	841451000	USD
CY2017	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	889212000	USD
CY2019	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	985345000	USD
CY2018	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	896145000	USD
CY2017	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	984506000	USD
CY2019	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	34064000	USD
CY2018	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	27134000	USD
CY2017	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	30439000	USD
CY2019	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	14415000	USD
CY2018	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	-1113000	USD
CY2017	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	-660000	USD
CY2019	us-gaap	Life Insurance Corporate Or Bank Owned Change In Value LifeInsuranceCorporateOrBankOwnedChangeInValue	2245000	USD
CY2018	us-gaap	Life Insurance Corporate Or Bank Owned Change In Value LifeInsuranceCorporateOrBankOwnedChangeInValue	2234000	USD
CY2017	us-gaap	Life Insurance Corporate Or Bank Owned Change In Value LifeInsuranceCorporateOrBankOwnedChangeInValue	1395000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	7475000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	3122000	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	2952000	USD
CY2019	us-gaap	Depreciation Nonproduction DepreciationNonproduction	18592000	USD
CY2018	us-gaap	Depreciation Nonproduction DepreciationNonproduction	16019000	USD
CY2017	us-gaap	Depreciation Nonproduction DepreciationNonproduction	14758000	USD
CY2019	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-73000	USD
CY2018	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-2130000	USD
CY2017	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	1641000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-356000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	6861000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	25887000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	8485000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	6270000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2494000	USD
CY2019	gbci	Variable Interest Entities Investment Amortization VariableInterestEntitiesInvestmentAmortization	9700000	USD
CY2018	gbci	Variable Interest Entities Investment Amortization VariableInterestEntitiesInvestmentAmortization	7639000	USD
CY2017	gbci	Variable Interest Entities Investment Amortization VariableInterestEntitiesInvestmentAmortization	4692000	USD
CY2019	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	-1899000	USD
CY2018	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	2741000	USD
CY2017	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	-2466000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-5078000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-348000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-1139000	USD
CY2019	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	312000	USD
CY2018	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	357000	USD
CY2017	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-135000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	254000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	11655000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-4558000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	226649000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	280711000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	254741000	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	712113000	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	226842000	USD
CY2017	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	247748000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	711838000	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	357876000	USD
CY2017	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	446695000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	1224231000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	820333000	USD
CY2017	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	36239000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	58750000	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	76832000	USD
CY2017	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	25187000	USD
CY2019	us-gaap	Proceeds From Loan And Lease Originations And Principal Collections1 ProceedsFromLoanAndLeaseOriginationsAndPrincipalCollections1	3250220000	USD
CY2018	us-gaap	Proceeds From Loan And Lease Originations And Principal Collections1 ProceedsFromLoanAndLeaseOriginationsAndPrincipalCollections1	2691953000	USD
CY2017	us-gaap	Proceeds From Loan And Lease Originations And Principal Collections1 ProceedsFromLoanAndLeaseOriginationsAndPrincipalCollections1	2099292000	USD
CY2019	gbci	Payments For Loans Originated Or Acquired PaymentsForLoansOriginatedOrAcquired	3623548000	USD
CY2018	gbci	Payments For Loans Originated Or Acquired PaymentsForLoansOriginatedOrAcquired	3460227000	USD
CY2017	gbci	Payments For Loans Originated Or Acquired PaymentsForLoansOriginatedOrAcquired	2740281000	USD
CY2019	us-gaap	Payments For Proceeds From Productive Assets PaymentsForProceedsFromProductiveAssets	16398000	USD
CY2018	us-gaap	Payments For Proceeds From Productive Assets PaymentsForProceedsFromProductiveAssets	18637000	USD
CY2017	us-gaap	Payments For Proceeds From Productive Assets PaymentsForProceedsFromProductiveAssets	10128000	USD
CY2019	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	4670000	USD
CY2018	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	9385000	USD
CY2017	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	12335000	USD
CY2019	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	118516000	USD
CY2018	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	87221000	USD
CY2017	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	68610000	USD
CY2019	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	97597000	USD
CY2018	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	87975000	USD
CY2017	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	71396000	USD
CY2019	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	0	USD
CY2018	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	1331000	USD
CY2017	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	437000	USD
CY2019	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	16348000	USD
CY2018	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	37956000	USD
CY2017	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	14514000	USD
CY2019	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	-79333000	USD
CY2018	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	-101268000	USD
CY2017	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	4091000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-42682000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-872420000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	23655000	USD
CY2019	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	285856000	USD
CY2018	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	599037000	USD
CY2017	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	-89397000	USD
CY2019	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	172264000	USD
CY2018	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	4398000	USD
CY2017	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	-111077000	USD
CY2019	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	-255000000	USD
CY2018	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	85000000	USD
CY2017	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	137200000	USD
CY2019	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	0	USD
CY2018	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	0	USD
CY2017	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	150000000	USD
CY2019	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	151160000	USD
CY2018	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	1198000	USD
CY2017	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	208192000	USD
CY2019	us-gaap	Proceeds From Repayments Of Other Debt ProceedsFromRepaymentsOfOtherDebt	14109000	USD
CY2018	us-gaap	Proceeds From Repayments Of Other Debt ProceedsFromRepaymentsOfOtherDebt	-5059000	USD
CY2017	us-gaap	Proceeds From Repayments Of Other Debt ProceedsFromRepaymentsOfOtherDebt	3784000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	124468000	USD
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	85493000	USD
CY2017	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	111720000	USD
CY2019	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	1293000	USD
CY2018	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	1214000	USD
CY2017	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	1531000	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	2896000	USD
CY2018	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	24000	USD
CY2017	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	0	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-56796000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	595495000	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-230933000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	127171000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	3786000	USD
CY2017	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	47463000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	203790000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	200004000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	152541000	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
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	200004000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	42461000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	35174000	USD
CY2017	us-gaap	Interest Paid Net InterestPaidNet	30000000	USD
CY2019	us-gaap	Income Taxes Paid IncomeTaxesPaid	36817000	USD
CY2018	us-gaap	Income Taxes Paid IncomeTaxesPaid	26489000	USD
CY2017	us-gaap	Income Taxes Paid IncomeTaxesPaid	40219000	USD
CY2019	us-gaap	Transfer Of Investments TransferOfInvestments	0	USD
CY2018	us-gaap	Transfer Of Investments TransferOfInvestments	270331000	USD
CY2017	us-gaap	Transfer Of Investments TransferOfInvestments	0	USD
CY2019	us-gaap	Transfer Of Other Real Estate TransferOfOtherRealEstate	7000	USD
CY2018	us-gaap	Transfer Of Other Real Estate TransferOfOtherRealEstate	406000	USD
CY2017	us-gaap	Transfer Of Other Real Estate TransferOfOtherRealEstate	553000	USD
CY2019	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	2349000	USD
CY2018	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	4924000	USD
CY2017	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	4466000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	9948000	USD
CY2018	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	0	USD
CY2017	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	0	USD
CY2019	gbci	Dividends Declared But Not Paid Duringthe Period DividendsDeclaredButNotPaidDuringthePeriod	18686000	USD
CY2018	gbci	Dividends Declared But Not Paid Duringthe Period DividendsDeclaredButNotPaidDuringthePeriod	25726000	USD
CY2017	gbci	Dividends Declared But Not Paid Duringthe Period DividendsDeclaredButNotPaidDuringthePeriod	265000	USD
CY2019	us-gaap	Stock Issued1 StockIssued1	316538000	USD
CY2018	us-gaap	Stock Issued1 StockIssued1	250807000	USD
CY2017	us-gaap	Stock Issued1 StockIssued1	46673000	USD
CY2019	gbci	Cash Considerationfor Outstanding Shares CashConsiderationforOutstandingShares	16424000	USD
CY2018	gbci	Cash Considerationfor Outstanding Shares CashConsiderationforOutstandingShares	16265000	USD
CY2017	gbci	Cash Considerationfor Outstanding Shares CashConsiderationforOutstandingShares	17342000	USD
CY2019	gbci	Business Combination Effective Settlementofa Pre Existing Relationship BusinessCombinationEffectiveSettlementofaPreExistingRelationship	0	USD
CY2018	gbci	Business Combination Effective Settlementofa Pre Existing Relationship BusinessCombinationEffectiveSettlementofaPreExistingRelationship	10054000	USD
CY2017	gbci	Business Combination Effective Settlementofa Pre Existing Relationship BusinessCombinationEffectiveSettlementofaPreExistingRelationship	0	USD
CY2019	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	1190267000	USD
CY2018	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	1660882000	USD
CY2017	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	355230000	USD
CY2019	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	1024137000	USD
CY2018	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	1383756000	USD
CY2017	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	321824000	USD
CY2019Q4	gbci	Number Of Bank Divisions NumberOfBankDivisions	16	division
CY2019	gbci	Maximum Periodof Original Maturitytobe Includedin Cashand Cash Equivalents MaximumPeriodofOriginalMaturitytobeIncludedinCashandCashEquivalents	three months
CY2019Q4	gbci	Federal Reserve Balance Or Cash On Hand Required FederalReserveBalanceOrCashOnHandRequired	50055000	USD
CY2019	gbci	Minimum Period Past Dueto Consider Loansas Delinquent MinimumPeriodPastDuetoConsiderLoansasDelinquent	P30D
CY2019	gbci	Minimum Period Past Dueto Consider Loansas Non Accrual MinimumPeriodPastDuetoConsiderLoansasNonAccrual	P90D
CY2019	gbci	Minimum Period Past Dueto Consider Loansas Non Accrual MinimumPeriodPastDuetoConsiderLoansasNonAccrual	P90D
CY2019	gbci	Minimum Period Past Dueto Consider Loansas Non Accrual MinimumPeriodPastDuetoConsiderLoansasNonAccrual	P90D
CY2019	gbci	Financing Receivable Allowancefor Credit Losses Numberof Quarters Usedto Evaluate Historical Loss Experience FinancingReceivableAllowanceforCreditLossesNumberofQuartersUsedtoEvaluateHistoricalLossExperience	12	quarter
CY2019	gbci	Financing Receivable Threshold Period Past Due Writeoff1 FinancingReceivableThresholdPeriodPastDueWriteoff1	P120D
CY2019	gbci	Maximum Term Leases Will Be Considered Short Term MaximumTermLeasesWillBeConsideredShortTerm	P12M
CY2019	gbci	Maximum Period Up To Which Purchase Price Of Business Is Allocated To Assets Acquired And Liabilities Assumed MaximumPeriodUpToWhichPurchasePriceOfBusinessIsAllocatedToAssetsAcquiredAndLiabilitiesAssumed	P1Y
CY2019	gbci	Numberofstepsincludedingoodwillimpairmenttest Numberofstepsincludedingoodwillimpairmenttest	2	step
CY2019	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	69877000	USD
CY2018	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	76664000	USD
CY2017	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	69808000	USD
CY2019	us-gaap	Advertising Cost Policy Expensed Advertising Cost AdvertisingCostPolicyExpensedAdvertisingCost	<div style="text-align:justify;"><span style="background-color:rgb(255,255,255, 0.0);color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;text-decoration: underline;">Advertising and Promotion</span></div><div style="text-align:justify;"><span style="background-color:rgb(255,255,255, 0.0);color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;">Advertising and promotion costs are recognized in the period incurred.</span></div>
CY2019	gbci	Percentage Of Likelihood For Term More Likely Than Not PercentageOfLikelihoodForTermMoreLikelyThanNot	0.50
CY2019	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	<div><span style="background-color:rgb(255,255,255, 0.0);color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;text-decoration: underline;">Reclassifications</span></div><div><span style="background-color:rgb(255,255,255, 0.0);color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;">Certain reclassifications have been made to the 2018 and 2017 financial statements to conform to the 2019 presentation.</span></div>
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
CY2019Q4	gbci	Debt Securities Amortized Cost Basis DebtSecuritiesAmortizedCostBasis	2745985000	USD
CY2019Q4	gbci	Securities Gross Unrealized Gain Accumulatedin Investments SecuritiesGrossUnrealizedGainAccumulatedinInvestments	65750000	USD
CY2019Q4	gbci	Securities Gross Unrealized Loss Accumulatedin Investments1 SecuritiesGrossUnrealizedLossAccumulatedinInvestments1	2087000	USD
CY2019Q4	gbci	Debt Securities Fair Value DebtSecuritiesFairValue	2809648000	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2580520000	USD
CY2018Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	23360000	USD
CY2018Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	32217000	USD
CY2018Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2571663000	USD
CY2018Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	297915000	USD
CY2018Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	1380000	USD
CY2018Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	11039000	USD
CY2018Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	288256000	USD
CY2018Q4	gbci	Debt Securities Amortized Cost Basis DebtSecuritiesAmortizedCostBasis	2878435000	USD
CY2018Q4	gbci	Securities Gross Unrealized Gain Accumulatedin Investments SecuritiesGrossUnrealizedGainAccumulatedinInvestments	24740000	USD
CY2018Q4	gbci	Securities Gross Unrealized Loss Accumulatedin Investments1 SecuritiesGrossUnrealizedLossAccumulatedinInvestments1	43256000	USD
CY2018Q4	gbci	Debt Securities Fair Value DebtSecuritiesFairValue	2859919000	USD
CY2018	us-gaap	Transfer Of Investments TransferOfInvestments	270331000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	62317000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	62555000	USD
CY2019Q4	us-gaap	Heldtomaturity Securities Debt Maturities Next Rolling Twelve Months Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCost	0	USD
CY2019Q4	us-gaap	Held To Maturity Securities Debt Maturities Next Rolling Twelve Months Fair Value HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	0	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis	170631000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	174195000	USD
CY2019Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Two Through Five Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCost	12841000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Two Through Five Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	13383000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis	206056000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	214517000	USD
CY2019Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCost	71708000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Six Through Ten Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	75771000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis	459230000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	472454000	USD
CY2019Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling After Ten Years Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost	140062000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Debt Maturities Rolling After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue	145242000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	898234000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate	923721000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Amortized Cost Basis HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	224611000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue	234396000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2521374000	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 Fair Value HeldToMaturitySecuritiesFairValue	234396000	USD
CY2019	gbci	Proceedsfrom Salesand Callsof Debt Securities Availableforsale ProceedsfromSalesandCallsofDebtSecuritiesAvailableforsale	928710000	USD
CY2018	gbci	Proceedsfrom Salesand Callsof Debt Securities Availableforsale ProceedsfromSalesandCallsofDebtSecuritiesAvailableforsale	265587000	USD
CY2017	gbci	Proceedsfrom Salesand Callsof Debt Securities Availableforsale ProceedsfromSalesandCallsofDebtSecuritiesAvailableforsale	280783000	USD
CY2019	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	18936000	USD
CY2018	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	443000	USD
CY2017	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	3369000	USD
CY2019	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	4513000	USD
CY2018	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	455000	USD
CY2017	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	4005000	USD
CY2019	gbci	Heldto Maturity Securities Gross Realized Gains Losses Sale Proceeds HeldtoMaturitySecuritiesGrossRealizedGainsLossesSaleProceeds	58750000	USD
CY2018	gbci	Heldto Maturity Securities Gross Realized Gains Losses Sale Proceeds HeldtoMaturitySecuritiesGrossRealizedGainsLossesSaleProceeds	79000000	USD
CY2017	gbci	Heldto Maturity Securities Gross Realized Gains Losses Sale Proceeds HeldtoMaturitySecuritiesGrossRealizedGainsLossesSaleProceeds	23020000	USD
CY2019	gbci	Heldto Maturity Securities Sold Security Realized Gain HeldtoMaturitySecuritiesSoldSecurityRealizedGain	2000	USD
CY2018	gbci	Heldto Maturity Securities Sold Security Realized Gain HeldtoMaturitySecuritiesSoldSecurityRealizedGain	101000	USD
CY2017	gbci	Heldto Maturity Securities Sold Security Realized Gain HeldtoMaturitySecuritiesSoldSecurityRealizedGain	204000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	32217000	USD
CY2019	gbci	Heldto Maturity Securities Sold Security Realized Loss HeldtoMaturitySecuritiesSoldSecurityRealizedLoss	10000	USD
CY2018	gbci	Heldto Maturity Securities Sold Security Realized Loss HeldtoMaturitySecuritiesSoldSecurityRealizedLoss	1202000	USD
CY2017	gbci	Heldto Maturity Securities Sold Security Realized Loss HeldtoMaturitySecuritiesSoldSecurityRealizedLoss	228000	USD
CY2019Q4	us-gaap	Security Owned And Pledged As Collateral Fair Value SecurityOwnedAndPledgedAsCollateralFairValue	1475752000	USD
CY2018Q4	us-gaap	Security Owned And Pledged As Collateral Fair Value SecurityOwnedAndPledgedAsCollateralFairValue	1333455000	USD
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
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	444401000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	3224000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	1016813000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	28993000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	1461214000	USD
CY2018Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	87392000	USD
CY2018Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	2778000	USD
CY2018Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	126226000	USD
CY2018Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	8261000	USD
CY2018Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue	213618000	USD
CY2018Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	11039000	USD
CY2019	gbci	Financing Receivable Numberof Portfolio Segments FinancingReceivableNumberofPortfolioSegments	3	portfolio_segment
CY2019Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	9512810000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	8287549000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	124490000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	131239000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	9388320000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	8156310000	USD
CY2019Q4	gbci	Unamortized Loan Origination Feesand Costs UnamortizedLoanOriginationFeesandCosts	-6964000	USD
CY2018Q4	gbci	Unamortized Loan Origination Feesand Costs UnamortizedLoanOriginationFeesandCosts	-5685000	USD
CY2019Q4	gbci	Unamortized Discountsand Premiumson Loans UnamortizedDiscountsandPremiumsonLoans	-21574000	USD
CY2018Q4	gbci	Unamortized Discountsand Premiumson Loans UnamortizedDiscountsandPremiumsonLoans	-25172000	USD
CY2019Q4	us-gaap	Loans Pledged As Collateral LoansPledgedAsCollateral	5228136000	USD
CY2019Q4	gbci	Percentage Of Consolidated Stockholders Equity Exceeding Which No Borrower Had Outstanding Loans Or Commitments PercentageOfConsolidatedStockholdersEquityExceedingWhichNoBorrowerHadOutstandingLoansOrCommitments	0.10
CY2019Q4	us-gaap	Servicing Asset At Amortized Value ServicingAssetAtAmortizedValue	185897000	USD
CY2018Q4	us-gaap	Servicing Asset At Amortized Value ServicingAssetAtAmortizedValue	181281000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	57825000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	59528000	USD
CY2019	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	17504000	USD
CY2019	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	19207000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	131239000	USD
CY2019	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	57000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	15178000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	8372000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	124490000	USD
CY2017Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	129568000	USD
CY2018	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	9953000	USD
CY2018	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	17807000	USD
CY2018	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	9525000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	131239000	USD
CY2016Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	129572000	USD
CY2017	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	10824000	USD
CY2017	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	19331000	USD
CY2017	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	8503000	USD
CY2017Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	129568000	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	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	124490000	USD
CY2018Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	108788000	USD
CY2018Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	8178761000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	8287549000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	3223000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	128016000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	131239000	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
CY2018Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	47252000	USD
CY2018Q4	gbci	Financing Receivable Recorded Investment Past Due And Non Accrual Loans FinancingReceivableRecordedInvestmentPastDueAndNonAccrualLoans	82837000	USD
CY2018Q4	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	8204712000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	8287549000	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
CY2018Q4	us-gaap	Impaired Financing Receivable With Related Allowance Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment	19197000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable With Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance	19491000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	3223000	USD
CY2018	us-gaap	Impaired Financing Receivable With Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment	19519000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	89591000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance	107486000	USD
CY2018	us-gaap	Impaired Financing Receivable With No Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment	106747000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	108788000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	126977000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	3223000	USD
CY2018	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	126266000	USD
CY2019	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	18	Loan
CY2019	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	18508000	USD
CY2019	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	18476000	USD
CY2019	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	1	Loan
CY2019	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	106000	USD
CY2018	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	25	Loan
CY2018	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	21995000	USD
CY2018	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	21881000	USD
CY2018	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	1	Loan
CY2018	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	47000	USD
CY2017	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	32	Loan
CY2017	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	41521000	USD
CY2017	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	38838000	USD
CY2017	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	1	Loan
CY2017	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	18000	USD
CY2019Q4	gbci	Tdr With Pre Modification Loan Balance For Which Oreo Was Received TdrWithPreModificationLoanBalanceForWhichOreoWasReceived	2992000	USD
CY2018Q4	gbci	Tdr With Pre Modification Loan Balance For Which Oreo Was Received TdrWithPreModificationLoanBalanceForWhichOreoWasReceived	6793000	USD
CY2017Q4	gbci	Tdr With Pre Modification Loan Balance For Which Oreo Was Received TdrWithPreModificationLoanBalanceForWhichOreoWasReceived	5987000	USD
CY2019Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	1744000	USD
CY2018Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	350000	USD
CY2019Q4	gbci	Real Estate Acquired Through Foreclosure Securedby Residential Real Estate RealEstateAcquiredThroughForeclosureSecuredbyResidentialRealEstate	1504000	USD
CY2018Q4	gbci	Real Estate Acquired Through Foreclosure Securedby Residential Real Estate RealEstateAcquiredThroughForeclosureSecuredbyResidentialRealEstate	698000	USD
CY2019Q4	gbci	Additional Outstanding Commitments On Troubled Debt Restructuring AdditionalOutstandingCommitmentsOnTroubledDebtRestructuring	3933000	USD
CY2018Q4	gbci	Additional Outstanding Commitments On Troubled Debt Restructuring AdditionalOutstandingCommitmentsOnTroubledDebtRestructuring	5335000	USD
CY2019	us-gaap	Financing Receivables Impaired Troubled Debt Restructuring Write Down FinancingReceivablesImpairedTroubledDebtRestructuringWriteDown	709000	USD
CY2018	us-gaap	Financing Receivables Impaired Troubled Debt Restructuring Write Down FinancingReceivablesImpairedTroubledDebtRestructuringWriteDown	1685000	USD
CY2017	us-gaap	Financing Receivables Impaired Troubled Debt Restructuring Write Down FinancingReceivablesImpairedTroubledDebtRestructuringWriteDown	2984000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	148373000	USD
CY2018Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	137237000	USD
CY2019Q4	gbci	Property Plan And Equipment Excluding Right Of Use Asset PropertyPlanAndEquipmentExcludingRightOfUseAsset	263236000	USD
CY2018Q4	gbci	Property Plan And Equipment Excluding Right Of Use Asset PropertyPlanAndEquipmentExcludingRightOfUseAsset	241528000	USD
CY2019Q4	gbci	Right Of Use Asset RightOfUseAsset	47073000	USD
CY2018Q4	gbci	Right Of Use Asset RightOfUseAsset	0	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	310309000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	241528000	USD
CY2019Q4	gbci	Finance Lease Right Of Use Asset Gross FinanceLeaseRightOfUseAssetGross	6537000	USD
CY2019Q4	gbci	Finance Lease Right Of Use Asset Accumulated Amortization FinanceLeaseRightOfUseAssetAccumulatedAmortization	917000	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
CY2019Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	5671000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	43904000	USD
CY2019Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P24Y
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P19Y
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
CY2019Q4	us-gaap	Finance Lease Liability Payments Due In Next Rolling Twelve Months FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths	335000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Rolling Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths	3965000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due In Rolling Year Two FinanceLeaseLiabilityPaymentsDueInRollingYearTwo	257000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Two LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo	3761000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due In Rolling Year Three FinanceLeaseLiabilityPaymentsDueInRollingYearThree	255000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Three LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree	3473000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due In Rolling Year Four FinanceLeaseLiabilityPaymentsDueInRollingYearFour	261000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Four LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour	3123000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due In Rolling Year Five FinanceLeaseLiabilityPaymentsDueInRollingYearFive	268000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Five LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive	3130000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due In Rolling After Year Five FinanceLeaseLiabilityPaymentsDueInRollingAfterYearFive	6797000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Rolling Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterRollingYearFive	45336000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	8173000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	62788000	USD
CY2019Q4	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	170000	USD
CY2019Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	2421000	USD
CY2019Q4	us-gaap	Finance Lease Liability Noncurrent FinanceLeaseLiabilityNoncurrent	5501000	USD
CY2019Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	41483000	USD
CY2019Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	5671000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	43904000	USD
CY2019Q4	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	2502000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	18884000	USD
CY2019	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	101000	USD
CY2019	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	34000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	4063000	USD
CY2019	us-gaap	Short Term Lease Cost ShortTermLeaseCost	431000	USD
CY2019	us-gaap	Variable Lease Cost VariableLeaseCost	896000	USD
CY2019	us-gaap	Sublease Income SubleaseIncome	6000	USD
CY2019	us-gaap	Lease Cost LeaseCost	5519000	USD
CY2019	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	34000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	2136000	USD
CY2019	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	98000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	289586000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	177811000	USD
CY2016Q4	us-gaap	Goodwill Goodwill	147053000	USD
CY2019	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	166832000	USD
CY2018	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	111775000	USD
CY2017	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	30758000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	456418000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	289586000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	177811000	USD
CY2019Q4	gbci	Qualified Affordable Housing Project Investments Commitment To Be Paid Year One QualifiedAffordableHousingProjectInvestmentsCommitmentToBePaidYearOne	11916000	USD
CY2019Q4	gbci	Qualified Affordable Housing Project Investments Commitment To Be Paid Year Two QualifiedAffordableHousingProjectInvestmentsCommitmentToBePaidYearTwo	7692000	USD
CY2019Q4	gbci	Qualified Affordable Housing Project Investments Commitment To Be Paid Year Three QualifiedAffordableHousingProjectInvestmentsCommitmentToBePaidYearThree	7471000	USD
CY2019Q4	gbci	Qualified Affordable Housing Project Investments Commitment To Be Paid Year Four QualifiedAffordableHousingProjectInvestmentsCommitmentToBePaidYearFour	130000	USD
CY2019Q4	gbci	Qualified Affordable Housing Project Investments Commitment To Be Paid Year Five QualifiedAffordableHousingProjectInvestmentsCommitmentToBePaidYearFive	309000	USD
CY2019Q4	gbci	Qualified Affordable Housing Project Investments Commitment To Be Paid Thereafter QualifiedAffordableHousingProjectInvestmentsCommitmentToBePaidThereafter	419000	USD
CY2019Q4	us-gaap	Qualified Affordable Housing Project Investments Commitment QualifiedAffordableHousingProjectInvestmentsCommitment	27937000	USD
CY2019	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	6289000	USD
CY2018	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	4926000	USD
CY2017	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	2507000	USD
CY2019	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	8547000	USD
CY2018	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	6550000	USD
CY2017	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	3827000	USD
CY2019Q4	us-gaap	Cash Fdic Insured Amount CashFDICInsuredAmount	250000	USD
CY2019Q4	gbci	Time Deposits That Meetor Exceed Fdic Insurance Limit TimeDepositsThatMeetorExceedFDICInsuranceLimit	281054000	USD
CY2018Q4	gbci	Time Deposits That Meetor Exceed Fdic Insurance Limit TimeDepositsThatMeetorExceedFDICInsuranceLimit	244999000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	706520000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	150925000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	55809000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	23584000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	21513000	USD
CY2019Q4	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	150000	USD
CY2019Q4	us-gaap	Time Deposits TimeDeposits	958501000	USD
CY2019Q4	gbci	Overdraft Demand Deposits Reclassified As Loans OverdraftDemandDepositsReclassifiedAsLoans	5514000	USD
CY2018Q4	gbci	Overdraft Demand Deposits Reclassified As Loans OverdraftDemandDepositsReclassifiedAsLoans	5992000	USD
CY2019Q4	us-gaap	Related Party Deposit Liabilities RelatedPartyDepositLiabilities	21723000	USD
CY2018Q4	us-gaap	Related Party Deposit Liabilities RelatedPartyDepositLiabilities	26260000	USD
CY2019Q4	us-gaap	Securities Sold Under Agreements To Repurchase Gross Including Not Subject To Master Netting Arrangement SecuritiesSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	569824000	USD
CY2018Q4	us-gaap	Securities Sold Under Agreements To Repurchase Gross Including Not Subject To Master Netting Arrangement SecuritiesSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	396151000	USD
CY2019Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities For Repurchase Agreements PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForRepurchaseAgreements	711210000	USD
CY2018Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities For Repurchase Agreements PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForRepurchaseAgreements	511294000	USD
CY2019Q4	us-gaap	Securities Sold Under Agreements To Repurchase Gross Including Not Subject To Master Netting Arrangement SecuritiesSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	569824000	USD
CY2018Q4	us-gaap	Securities Sold Under Agreements To Repurchase Gross Including Not Subject To Master Netting Arrangement SecuritiesSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	396151000	USD
CY2019	us-gaap	Gain Loss On Contract Termination GainLossOnContractTermination	-3531000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due Within One Year Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueWithinOneYearOfBalanceSheetDate	31492000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate Of Amounts Due Within One Year Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueWithinOneYearOfBalanceSheetDate	0.0181
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due Within One Year Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueWithinOneYearOfBalanceSheetDate	285847000	USD
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate Of Amounts Due Within One Year Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueWithinOneYearOfBalanceSheetDate	0.0263
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due From One To Two Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromOneToTwoYearsOfBalanceSheetDate	5000000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate One To Two Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOneToTwoYearsFromBalanceSheetDate	0.0295
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due From One To Two Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromOneToTwoYearsOfBalanceSheetDate	1572000	USD
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate One To Two Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOneToTwoYearsFromBalanceSheetDate	0.0350
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due From Two To Three Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromTwoToThreeYearsOfBalanceSheetDate	889000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate Two To Three Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateTwoToThreeYearsFromBalanceSheetDate	0.0525
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due From Two To Three Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromTwoToThreeYearsOfBalanceSheetDate	150370000	USD
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate Two To Three Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateTwoToThreeYearsFromBalanceSheetDate	0.0377
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due From Three To Four Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromThreeToFourYearsOfBalanceSheetDate	165000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate Three To Four Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateThreeToFourYearsFromBalanceSheetDate	0.0545
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due From Three To Four Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromThreeToFourYearsOfBalanceSheetDate	918000	USD
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate Three To Four Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateThreeToFourYearsFromBalanceSheetDate	0.0525
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due From Four To Five Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromFourToFiveYearsOfBalanceSheetDate	780000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate Four To Five Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateFourToFiveYearsFromBalanceSheetDate	0.0431
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due From Four To Five Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromFourToFiveYearsOfBalanceSheetDate	204000	USD
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate Four To Five Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateFourToFiveYearsFromBalanceSheetDate	0.0545
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due After Five Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueAfterFiveYearsOfBalanceSheetDate	285000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate After Five Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateAfterFiveYearsFromBalanceSheetDate	0.0631
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Due After Five Years Of Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryDueAfterFiveYearsOfBalanceSheetDate	1264000	USD
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate After Five Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateAfterFiveYearsFromBalanceSheetDate	0.0482
CY2019Q4	us-gaap	Advances From Federal Home Loan Banks AdvancesFromFederalHomeLoanBanks	38611000	USD
CY2019Q4	gbci	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRate	0.0214
CY2018Q4	us-gaap	Advances From Federal Home Loan Banks AdvancesFromFederalHomeLoanBanks	440175000	USD
CY2018Q4	gbci	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRate	0.0303
CY2019Q4	us-gaap	Line Of Credit Facility Maximum Borrowing Capacity LineOfCreditFacilityMaximumBorrowingCapacity	230000000	USD
CY2019Q4	us-gaap	Subordinated Debt SubordinatedDebt	139914000	USD
CY2019	gbci	Maximum Numberof Consecutive Quartersfor Deferralof Interest Paymentson Trust Preferred Securities MaximumNumberofConsecutiveQuartersforDeferralofInterestPaymentsonTrustPreferredSecurities	20
CY2019Q4	gbci	Size Of Company Eligible For Tier1 Grandfather Provision SizeOfCompanyEligibleForTier1GrandfatherProvision	15000000000
CY2019Q4	gbci	Size Of Company Eligible For Tier1 Grandfather Provision SizeOfCompanyEligibleForTier1GrandfatherProvision	15000000000
CY2019	us-gaap	Business Combination Integration Related Costs BusinessCombinationIntegrationRelatedCosts	8503000	USD
CY2019Q4	gbci	Capital Conservation Buffer To Risk Weighted Assets Current Year CapitalConservationBufferToRiskWeightedAssetsCurrentYear	0.025
CY2019Q4	us-gaap	Capital Capital	1661249000	USD
CY2019Q4	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1495
CY2019Q4	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	888986000	USD
CY2019Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2019Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	1528683000	USD
CY2019Q4	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.1376
CY2019Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	666740000	USD
CY2019Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2019Q4	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	1398183000	USD
CY2019Q4	us-gaap	Common Equity Tier One Capital Ratio CommonEquityTierOneCapitalRatio	0.1258
CY2019Q4	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	500055000	USD
CY2019Q4	gbci	Tier One Common Capital Requiredfor Capital Adequacyto Risk Weighted Assets TierOneCommonCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.0450
CY2019Q4	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	1528683000	USD
CY2019Q4	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.1165
CY2019Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	524987000	USD
CY2019Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2018Q4	us-gaap	Capital Capital	1437889000	USD
CY2018Q4	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1470
CY2018Q4	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	782453000	USD
CY2018Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2018Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	1308017000	USD
CY2018Q4	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.1337
CY2018Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	586840000	USD
CY2018Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2018Q4	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	1183517000	USD
CY2018Q4	us-gaap	Common Equity Tier One Capital Ratio CommonEquityTierOneCapitalRatio	0.1210
CY2018Q4	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	440130000	USD
CY2018Q4	gbci	Tier One Common Capital Requiredfor Capital Adequacyto Risk Weighted Assets TierOneCommonCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.0450
CY2018Q4	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	1308017000	USD
CY2018Q4	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.1135
CY2018Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	461130000	USD
CY2018Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	2041367	shares
CY2018	us-gaap	Business Combination Integration Related Costs BusinessCombinationIntegrationRelatedCosts	6618000	USD
CY2017	us-gaap	Business Combination Integration Related Costs BusinessCombinationIntegrationRelatedCosts	2130000	USD
CY2019	gbci	Consulting Fees ConsultingFees	8276000	USD
CY2018	gbci	Consulting Fees ConsultingFees	7219000	USD
CY2017	gbci	Consulting Fees ConsultingFees	5331000	USD
CY2019	gbci	Debit Card Expense DebitCardExpense	5968000	USD
CY2018	gbci	Debit Card Expense DebitCardExpense	5104000	USD
CY2017	gbci	Debit Card Expense DebitCardExpense	7189000	USD
CY2019	gbci	Miscellaneous Employee Expenses MiscellaneousEmployeeExpenses	5138000	USD
CY2018	gbci	Miscellaneous Employee Expenses MiscellaneousEmployeeExpenses	4412000	USD
CY2017	gbci	Miscellaneous Employee Expenses MiscellaneousEmployeeExpenses	4160000	USD
CY2019	gbci	Telephone Expenses TelephoneExpenses	4827000	USD
CY2018	gbci	Telephone Expenses TelephoneExpenses	4487000	USD
CY2017	gbci	Telephone Expenses TelephoneExpenses	3891000	USD
CY2019	us-gaap	Business Development BusinessDevelopment	4446000	USD
CY2018	us-gaap	Business Development BusinessDevelopment	4172000	USD
CY2017	us-gaap	Business Development BusinessDevelopment	3333000	USD
CY2019	gbci	Vie Writedowns Lossesand Other Expenses VIEWritedownsLossesandOtherExpenses	4341000	USD
CY2018	gbci	Vie Writedowns Lossesand Other Expenses VIEWritedownsLossesandOtherExpenses	3618000	USD
CY2017	gbci	Vie Writedowns Lossesand Other Expenses VIEWritedownsLossesandOtherExpenses	3109000	USD
CY2019	gbci	Loan Related Expenses LoanRelatedExpenses	4140000	USD
CY2018	gbci	Loan Related Expenses LoanRelatedExpenses	3462000	USD
CY2017	gbci	Loan Related Expenses LoanRelatedExpenses	3080000	USD
CY2019	us-gaap	Postage Expense PostageExpense	3437000	USD
CY2018	us-gaap	Postage Expense PostageExpense	3104000	USD
CY2017	us-gaap	Postage Expense PostageExpense	2684000	USD
CY2019	us-gaap	Supplies Expense SuppliesExpense	3256000	USD
CY2018	us-gaap	Supplies Expense SuppliesExpense	3264000	USD
CY2017	us-gaap	Supplies Expense SuppliesExpense	2661000	USD
CY2019	gbci	Deposit Related Expenses DepositRelatedExpenses	1757000	USD
CY2018	gbci	Deposit Related Expenses DepositRelatedExpenses	1234000	USD
CY2017	gbci	Deposit Related Expenses DepositRelatedExpenses	1760000	USD
CY2019	gbci	Accounting Fees AccountingFees	1712000	USD
CY2018	gbci	Accounting Fees AccountingFees	1456000	USD
CY2017	gbci	Accounting Fees AccountingFees	1848000	USD
CY2019	gbci	Atm Expenses ATMExpenses	1700000	USD
CY2018	gbci	Atm Expenses ATMExpenses	1217000	USD
CY2017	gbci	Atm Expenses ATMExpenses	1720000	USD
CY2019	us-gaap	Legal Fees LegalFees	1245000	USD
CY2018	us-gaap	Legal Fees LegalFees	1763000	USD
CY2017	us-gaap	Legal Fees LegalFees	1106000	USD
CY2019	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	4029000	USD
CY2018	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	3164000	USD
CY2017	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	3043000	USD
CY2019	us-gaap	Other Noninterest Expense OtherNoninterestExpense	62775000	USD
CY2018	us-gaap	Other Noninterest Expense OtherNoninterestExpense	54294000	USD
CY2017	us-gaap	Other Noninterest Expense OtherNoninterestExpense	47045000	USD
CY2017	gbci	Federal Tax Rate Priorto Enactmentof The Tax Cutsand Jobs Act FederalTaxRatePriortoEnactmentofTheTaxCutsandJobsAct	0.35
CY2017	gbci	Federal Tax Rate Subsequentto Enactmentof The Tax Cutsand Jobs Act FederalTaxRateSubsequenttoEnactmentofTheTaxCutsandJobsAct	0.21
CY2017	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	19699000	USD
CY2017	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.046
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	34461000	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	21510000	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	29555000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	14545000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	11960000	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	9183000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	49006000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	33470000	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	38738000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-279000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	5372000	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	22246000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-77000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	1489000	USD
CY2017	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	3641000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-356000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	6861000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	25887000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	48650000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	40331000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	64625000	USD
CY2019	us-gaap	Other Tax Expense Benefit OtherTaxExpenseBenefit	-317000	USD
CY2018	us-gaap	Other Tax Expense Benefit OtherTaxExpenseBenefit	-443000	USD
CY2017	us-gaap	Other Tax Expense Benefit OtherTaxExpenseBenefit	-644000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.350
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.044
CY2018	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.048
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0.109
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.037
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.050
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.105
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.045
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.042
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.032
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.016
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.016
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.011
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.188
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.182
CY2017	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.357
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	31698000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	33313000	USD
CY2019Q4	gbci	Deferred Tax Assets Operating Lease Liabilities DeferredTaxAssetsOperatingLeaseLiabilities	11127000	USD
CY2018Q4	gbci	Deferred Tax Assets Operating Lease Liabilities DeferredTaxAssetsOperatingLeaseLiabilities	0	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	7447000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	6251000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	6646000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	5652000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Equity Method Investments DeferredTaxAssetsEquityMethodInvestments	5480000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Equity Method Investments DeferredTaxAssetsEquityMethodInvestments	6380000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	2209000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	2525000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Unrealized Losses On Availablefor Sale Securities Gross DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	0	USD
CY2018Q4	us-gaap	Deferred Tax Assets Unrealized Losses On Availablefor Sale Securities Gross DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	2244000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	3891000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	3841000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	68498000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	60206000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	16469000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	12667000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	13987000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	10776000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other Comprehensive Income DeferredTaxLiabilitiesOtherComprehensiveIncome	13652000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Other Comprehensive Income DeferredTaxLiabilitiesOtherComprehensiveIncome	0	USD
CY2019Q4	gbci	Deferred Tax Liabilities Operating Lease Rou Assets DeferredTaxLiabilitiesOperatingLeaseROUAssets	10506000	USD
CY2018Q4	gbci	Deferred Tax Liabilities Operating Lease Rou Assets DeferredTaxLiabilitiesOperatingLeaseROUAssets	0	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Tax Deferred Income DeferredTaxLiabilitiesTaxDeferredIncome	7311000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Tax Deferred Income DeferredTaxLiabilitiesTaxDeferredIncome	6436000	USD
CY2019Q4	gbci	Deferred Tax Liabilities Stock Dividends DeferredTaxLiabilitiesStockDividends	1486000	USD
CY2018Q4	gbci	Deferred Tax Liabilities Stock Dividends DeferredTaxLiabilitiesStockDividends	2722000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	3050000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	4041000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	66461000	USD
CY2018Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	36642000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	2037000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	23564000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	210544000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	181878000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	116377000	USD
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	88255290	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	83603515	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	77537664	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	130485	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	73670	shares
CY2017	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	69941	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	88385775	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	83677185	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	77607605	shares
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.39
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.18
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.50
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.38
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.17
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.50
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	0	shares
CY2018	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1357	shares
CY2017	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	0	shares
CY2019Q3	us-gaap	Interest Expense InterestExpense	10947000	USD
CY2019Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	126116000	USD
CY2019Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	132385000	USD
CY2019Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	142395000	USD
CY2019Q4	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	145281000	USD
CY2019Q1	us-gaap	Interest Expense InterestExpense	10904000	USD
CY2019Q2	us-gaap	Interest Expense InterestExpense	12089000	USD
CY2019Q4	us-gaap	Interest Expense InterestExpense	8833000	USD
CY2019Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	115212000	USD
CY2019Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	120296000	USD
CY2019Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	131448000	USD
CY2019Q4	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	136448000	USD
CY2019Q1	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	57000	USD
CY2019Q2	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	0	USD
CY2019Q3	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	0	USD
CY2019Q4	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	0	USD
CY2019Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11667000	USD
CY2019Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	12568000	USD
CY2018Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	122905000	USD
CY2019Q1	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	115155000	USD
CY2019Q2	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	120296000	USD
CY2019Q3	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	131448000	USD
CY2019Q4	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	136448000	USD
CY2019Q1	us-gaap	Noninterest Income NoninterestIncome	28474000	USD
CY2019Q2	us-gaap	Noninterest Income NoninterestIncome	30834000	USD
CY2019Q3	us-gaap	Noninterest Income NoninterestIncome	43049000	USD
CY2019Q4	us-gaap	Noninterest Income NoninterestIncome	28417000	USD
CY2019Q1	us-gaap	Noninterest Expense NoninterestExpense	82830000	USD
CY2019Q2	us-gaap	Noninterest Expense NoninterestExpense	86170000	USD
CY2019Q3	us-gaap	Noninterest Expense NoninterestExpense	110675000	USD
CY2019Q4	us-gaap	Noninterest Expense NoninterestExpense	95252000	USD
CY2019Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	60799000	USD
CY2019Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	64960000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	63822000	USD
CY2019Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	69613000	USD
CY2018Q4	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	125310000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	51610000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	57410000	USD
CY2019Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	12212000	USD
CY2019Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	12203000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	49132000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	52392000	USD
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.58
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.61
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.57
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.62
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.58
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.61
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.57
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.62
CY2018Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	103066000	USD
CY2018Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	117715000	USD
CY2018Q1	us-gaap	Interest Expense InterestExpense	7774000	USD
CY2018Q2	us-gaap	Interest Expense InterestExpense	9161000	USD
CY2018Q3	us-gaap	Interest Expense InterestExpense	9160000	USD
CY2018Q4	us-gaap	Interest Expense InterestExpense	9436000	USD
CY2018Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	95292000	USD
CY2018Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	108554000	USD
CY2018Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	113745000	USD
CY2018Q4	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	115874000	USD
CY2018Q1	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	795000	USD
CY2018Q2	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	4718000	USD
CY2018Q3	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	3194000	USD
CY2018Q4	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	1246000	USD
CY2018Q1	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	94497000	USD
CY2018Q2	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	103836000	USD
CY2018Q3	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	110551000	USD
CY2018Q4	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	114628000	USD
CY2018Q1	us-gaap	Noninterest Income NoninterestIncome	26086000	USD
CY2018Q2	us-gaap	Noninterest Income NoninterestIncome	31828000	USD
CY2018Q3	us-gaap	Noninterest Income NoninterestIncome	32416000	USD
CY2018Q4	us-gaap	Noninterest Income NoninterestIncome	28494000	USD
CY2018Q1	us-gaap	Noninterest Expense NoninterestExpense	73627000	USD
CY2018Q2	us-gaap	Noninterest Expense NoninterestExpense	81795000	USD
CY2018Q3	us-gaap	Noninterest Expense NoninterestExpense	82829000	USD
CY2018Q4	us-gaap	Noninterest Expense NoninterestExpense	81876000	USD
CY2018Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	46956000	USD
CY2018Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	53869000	USD
CY2018Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	60138000	USD
CY2018Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	61246000	USD
CY2018Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	8397000	USD
CY2018Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	9485000	USD
CY2018Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	10802000	USD
CY2018Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11647000	USD
CY2018Q1	us-gaap	Net Income Loss NetIncomeLoss	38559000	USD
CY2018Q2	us-gaap	Net Income Loss NetIncomeLoss	44384000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	49336000	USD
CY2018Q4	us-gaap	Net Income Loss NetIncomeLoss	49599000	USD
CY2018Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.48
CY2018Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.53
CY2018Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.58
CY2018Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
CY2018Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.48
CY2018Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.52
CY2018Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.58
CY2018Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.59
CY2019Q4	us-gaap	Other Commitment OtherCommitment	2482673000	USD
CY2018Q4	us-gaap	Other Commitment OtherCommitment	1993779000	USD

Files In Submission

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0000868671-20-000032-index-headers.html	Edgar Link	pending
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0000868671-20-000032.txt	Edgar Link	pending
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$GBCI
GLACIER BANCORP, INC. Stock $gbci

2019 Q4 Form 10-K Financial Statement

#000086867120000032 Filed on February 21, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$GBCI GLACIER BANCORP, INC. Stock $gbci

2019 Q4 Form 10-K Financial Statement

#000086867120000032 Filed on February 21, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$GBCI
GLACIER BANCORP, INC. Stock $gbci