$COLB
COLUMBIA BANKING SYSTEM, INC. Stock $colb

$colb Overview Financials Valuation SEC Filings Company Website

2019 Q4 Form 10-K Financial Statement

#000088734320000070 Filed on February 27, 2020

Income Statement

Concept	2019 Q4	2019 Q3	2019 Q2
Revenue	$133.1M	$132.5M	$135.4M
YoY Change	2.55%	3.89%	12.34%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development		$5.102M	$4.601M
YoY Change		14.24%	-11.88%
% of Gross Profit
Depreciation & Amortization	$8.000M	$8.900M	$9.100M
YoY Change	11.11%	-1.11%	-1.09%
% of Gross Profit
Operating Expenses		$5.102M	$4.601M
YoY Change		14.24%	-11.88%
Operating Profit
YoY Change
Interest Expense	$8.292M	$10.08M	$10.31M
YoY Change	40.23%	110.99%	165.96%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$58.03M	$63.11M	$63.82M
YoY Change	4.6%	9.14%	23.32%
Income Tax	$11.90M	$12.38M	$12.09M
% Of Pretax Income	20.51%	19.61%	18.95%
Net Earnings	$46.13M	$50.73M	$51.72M
YoY Change	3.09%	9.29%	23.89%
Net Earnings / Revenue	34.66%	38.27%	38.19%
Basic Earnings Per Share	$0.64	$0.70	$0.71
Diluted Earnings Per Share	$0.64	$0.70	$0.71
COMMON SHARES
Basic Shares Outstanding	72.14M shares	71.80M shares	72.45M shares
Diluted Shares Outstanding		71.80M shares	72.45M shares

Balance Sheet

Concept	2019 Q4	2019 Q3	2019 Q2
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$247.7M	$298.6M	$258.7M
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	$165.4M	$165.4M	$167.3M
YoY Change	-2.0%	-2.5%	-0.61%
Goodwill	$765.8M	$765.8M	$765.8M
YoY Change	0.0%	0.0%	0.0%
Intangibles	$35.46M	$37.91M	$40.54M
YoY Change	-22.81%	-22.36%	-21.88%
Long-Term Investments
YoY Change
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$14.08B	$13.76B	$13.09B
YoY Change	7.52%	6.18%	3.66%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$63.00M	$57.00M	$54.00M
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$64.00M	$24.00M	$50.00M
YoY Change	4.92%	-61.29%	8.7%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$63.00M	$57.00M	$54.00M
YoY Change	3.28%	-8.06%	17.39%
LONG-TERM LIABILITIES
Long-Term Debt	$35.00M	$35.00M	$35.00M
YoY Change	0.0%	-2.78%	-2.78%
Other Long-Term Liabilities	$119.0M	$131.0M	$111.0M
YoY Change	11.21%	22.43%	13.27%
Total Long-Term Liabilities	$154.0M	$166.0M	$146.0M
YoY Change	8.45%	16.08%	8.96%
TOTAL LIABILITIES
Total Short-Term Liabilities	$63.00M	$57.00M	$54.00M
Total Long-Term Liabilities	$154.0M	$166.0M	$146.0M
Total Liabilities	$11.92B	$11.60B	$10.96B
YoY Change	7.76%	5.66%	2.75%
SHAREHOLDERS EQUITY
Retained Earnings	$519.7M	$493.7M	$463.4M
YoY Change	21.79%	20.05%	20.72%
Common Stock	$1.651B	$1.648B	$1.645B
YoY Change	0.52%	0.5%	0.49%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$50.83M	$45.38M	$21.86M
YoY Change
Treasury Stock Shares	1.453M shares	1.300M shares	624.0K shares
Shareholders Equity	$2.160B	$2.162B	$2.134B
YoY Change
Total Liabilities & Shareholders Equity	$14.08B	$13.76B	$13.09B
YoY Change	7.52%	6.18%	3.66%

Cashflow Statement

Concept	2019 Q4	2019 Q3	2019 Q2
OPERATING ACTIVITIES
Net Income	$46.13M	$50.73M	$51.72M
YoY Change	3.09%	9.29%	23.89%
Depreciation, Depletion And Amortization	$8.000M	$8.900M	$9.100M
YoY Change	11.11%	-1.11%	-1.09%
Cash From Operating Activities	$49.90M	$56.30M	$46.00M
YoY Change	-24.39%	-0.71%	-35.21%
INVESTING ACTIVITIES
Capital Expenditures	-$2.600M	-$2.300M	-$1.700M
YoY Change	-13.33%	-30.3%	-41.38%
Acquisitions
YoY Change
Other Investing Activities	-$402.7M	-$586.9M	$80.40M
YoY Change	377.7%	63.03%	-154.43%
Cash From Investing Activities	-$405.4M	-$589.2M	$78.70M
YoY Change	363.84%	62.22%	-152.26%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	304.5M	572.8M	-78.10M
YoY Change	436.09%	100.91%	-257.78%
NET CHANGE
Cash From Operating Activities	49.90M	56.30M	46.00M
Cash From Investing Activities	-405.4M	-589.2M	78.70M
Cash From Financing Activities	304.5M	572.8M	-78.10M
Net Change In Cash	-51.00M	39.90M	46.60M
YoY Change	-244.07%	-286.45%	-254.82%
FREE CASH FLOW
Cash From Operating Activities	$49.90M	$56.30M	$46.00M
Capital Expenditures	-$2.600M	-$2.300M	-$1.700M
Free Cash Flow	$52.50M	$58.60M	$47.70M
YoY Change	-23.91%	-2.33%	-35.45%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2019	colb	Look Back Period Under Employee Stock Purchase Plan LookBackPeriodUnderEmployeeStockPurchasePlan	P6M
CY2018Q4	colb	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing Number Of Loans FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruingNumberOfLoans	0
CY2019	colb	Number Of Days Used To Determine Treatment As Cash Equivalent NumberOfDaysUsedToDetermineTreatmentAsCashEquivalent	P90D
CY2019	colb	Number Of Look Back Period Under Employee Stock Purchase Plan NumberOfLookBackPeriodUnderEmployeeStockPurchasePlan	2	period
CY2019	colb	Numberof Daysof Delinquencyat Which Loans Are Categorized As Non Accrual Status NumberofDaysofDelinquencyatWhichLoansAreCategorizedAsNonAccrualStatus	P90D
CY2019	dei	Amendment Flag AmendmentFlag	false
CY2019	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2019	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2019	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2019
CY2019	dei	Entity Central Index Key EntityCentralIndexKey	0000887343
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CY2018	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.14
CY2019	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.40
CY2018Q4	us-gaap	Common Stock No Par Value CommonStockNoParValue	0
CY2019Q4	us-gaap	Common Stock No Par Value CommonStockNoParValue	0
CY2018Q4	us-gaap	Deferred Tax Liability Not Recognized Amount Of Unrecognized Deferred Tax Liability Undistributed Earnings Of Domestic Subsidiaries DeferredTaxLiabilityNotRecognizedAmountOfUnrecognizedDeferredTaxLiabilityUndistributedEarningsOfDomesticSubsidiaries	0	USD
CY2018Q4	us-gaap	Fair Value Liabilities Level1 To Level2 Transfers Amount FairValueLiabilitiesLevel1ToLevel2TransfersAmount	0	USD
CY2017	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0
CY2018	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0
CY2017	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
CY2018	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
CY2017	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	-2287000	USD
CY2018	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	-7000	USD
CY2019	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	619000	USD
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CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax	-3562000	USD
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CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax	138000	USD
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CY2018	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	0	USD
CY2019	dei	Document Type DocumentType	10-K
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CY2019	dei	Entity File Number EntityFileNumber	0-20288
CY2019	dei	Entity Registrant Name EntityRegistrantName	COLUMBIA BANKING SYSTEM, INC.
CY2019	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	WA
CY2019	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	91-1422237
CY2019	dei	Entity Address Address Line1 EntityAddressAddressLine1	1301 A Street
CY2019	dei	Entity Address City Or Town EntityAddressCityOrTown	Tacoma
CY2019	dei	Entity Address State Or Province EntityAddressStateOrProvince	WA
CY2019	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	98402-2156
CY2019	dei	City Area Code CityAreaCode	253
CY2019	dei	Local Phone Number LocalPhoneNumber	305-1900
CY2019	dei	Security12b Title Security12bTitle	Common Stock, No Par Value
CY2019	dei	Trading Symbol TradingSymbol	COLB
CY2019	dei	Security Exchange Name SecurityExchangeName	NASDAQ
CY2019	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2019	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
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CY2017	us-gaap	Interest Expense Other Short Term Borrowings InterestExpenseOtherShortTermBorrowings	575000	USD
CY2019	us-gaap	Interest Expense InterestExpense	36547000	USD
CY2018	us-gaap	Interest Expense InterestExpense	18230000	USD
CY2017	us-gaap	Interest Expense InterestExpense	6757000	USD
CY2019	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	493405000	USD
CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	478839000	USD
CY2017	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	367989000	USD
CY2019	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3493000	USD
CY2018	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	14769000	USD
CY2017	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	8631000	USD
CY2019	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	489912000	USD
CY2018	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	464070000	USD
CY2017	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	359358000	USD
CY2019	colb	Depositaccountandtreasurymanagementfees Depositaccountandtreasurymanagementfees	35695000	USD
CY2018	colb	Depositaccountandtreasurymanagementfees Depositaccountandtreasurymanagementfees	36072000	USD
CY2017	colb	Depositaccountandtreasurymanagementfees Depositaccountandtreasurymanagementfees	30381000	USD
CY2019	colb	Cardrevenue Cardrevenue	15198000	USD
CY2018	colb	Cardrevenue Cardrevenue	19719000	USD
CY2017	colb	Cardrevenue Cardrevenue	25627000	USD
CY2019	colb	Financialservicesandtrustrevenue Financialservicesandtrustrevenue	12799000	USD
CY2018	colb	Financialservicesandtrustrevenue Financialservicesandtrustrevenue	12135000	USD
CY2017	colb	Financialservicesandtrustrevenue Financialservicesandtrustrevenue	11478000	USD
CY2019	colb	Loanrevenue Loanrevenue	13465000	USD
CY2018	colb	Loanrevenue Loanrevenue	11866000	USD
CY2017	colb	Loanrevenue Loanrevenue	12399000	USD
CY2019	colb	Merchantprocessingrevenue Merchantprocessingrevenue	0	USD
CY2018	colb	Merchantprocessingrevenue Merchantprocessingrevenue	0	USD
CY2017	colb	Merchantprocessingrevenue Merchantprocessingrevenue	4283000	USD
CY2019	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	6294000	USD
CY2018	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	6007000	USD
CY2017	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	5380000	USD
CY2019	us-gaap	Available For Sale Securities Gross Realized Gain Loss Net AvailableForSaleSecuritiesGrossRealizedGainLossNet	2132000	USD
CY2018	us-gaap	Available For Sale Securities Gross Realized Gain Loss Net AvailableForSaleSecuritiesGrossRealizedGainLossNet	-89000	USD
CY2017	us-gaap	Available For Sale Securities Gross Realized Gain Loss Net AvailableForSaleSecuritiesGrossRealizedGainLossNet	-11000	USD
CY2019	colb	Gainonsaleofmerchantcardservicesportfolio Gainonsaleofmerchantcardservicesportfolio	0	USD
CY2018	colb	Gainonsaleofmerchantcardservicesportfolio Gainonsaleofmerchantcardservicesportfolio	0	USD
CY2017	us-gaap	Other Noninterest Expense OtherNoninterestExpense	34608000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	345482000	USD
CY2017	colb	Gainonsaleofmerchantcardservicesportfolio Gainonsaleofmerchantcardservicesportfolio	14000000	USD
CY2019	colb	Change In Federal Deposit Insurance Corporation Loss Sharing Asset ChangeInFederalDepositInsuranceCorporationLossSharingAsset	0	USD
CY2018	colb	Change In Federal Deposit Insurance Corporation Loss Sharing Asset ChangeInFederalDepositInsuranceCorporationLossSharingAsset	0	USD
CY2017	colb	Change In Federal Deposit Insurance Corporation Loss Sharing Asset ChangeInFederalDepositInsuranceCorporationLossSharingAsset	-447000	USD
CY2019	us-gaap	Noninterest Income Other NoninterestIncomeOther	11598000	USD
CY2018	us-gaap	Noninterest Income Other NoninterestIncomeOther	2546000	USD
CY2017	us-gaap	Noninterest Income Other NoninterestIncomeOther	6552000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	97181000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	88256000	USD
CY2017	us-gaap	Noninterest Income NoninterestIncome	109642000	USD
CY2019	us-gaap	Labor And Related Expense LaborAndRelatedExpense	212867000	USD
CY2018	us-gaap	Labor And Related Expense LaborAndRelatedExpense	200199000	USD
CY2017	us-gaap	Labor And Related Expense LaborAndRelatedExpense	169674000	USD
CY2019	us-gaap	Occupancy Net OccupancyNet	35176000	USD
CY2018	us-gaap	Occupancy Net OccupancyNet	36576000	USD
CY2017	us-gaap	Occupancy Net OccupancyNet	32407000	USD
CY2019	us-gaap	Communications And Information Technology CommunicationsAndInformationTechnology	19164000	USD
CY2018	us-gaap	Communications And Information Technology CommunicationsAndInformationTechnology	20235000	USD
CY2017	us-gaap	Communications And Information Technology CommunicationsAndInformationTechnology	18205000	USD
CY2019	us-gaap	Professional Fees ProfessionalFees	21645000	USD
CY2018	us-gaap	Professional Fees ProfessionalFees	18044000	USD
CY2017	us-gaap	Professional Fees ProfessionalFees	15151000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	10479000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	12236000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	6333000	USD
CY2019	colb	Businessand Occupationtaxes BusinessandOccupationtaxes	5846000	USD
CY2018	colb	Businessand Occupationtaxes BusinessandOccupationtaxes	5664000	USD
CY2017	colb	Businessand Occupationtaxes BusinessandOccupationtaxes	4326000	USD
CY2019	us-gaap	Advertising Expense AdvertisingExpense	4925000	USD
CY2018	us-gaap	Advertising Expense AdvertisingExpense	5584000	USD
CY2017	us-gaap	Advertising Expense AdvertisingExpense	4466000	USD
CY2019	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1920000	USD
CY2018	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	3710000	USD
CY2017	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	3183000	USD
CY2019	colb	Merchant Processing MerchantProcessing	0	USD
CY2018	colb	Merchant Processing MerchantProcessing	0	USD
CY2017	colb	Merchant Processing MerchantProcessing	2196000	USD
CY2019	colb	Netcostbenefitofoperationofotherrealestateowned Netcostbenefitofoperationofotherrealestateowned	-692000	USD
CY2018	colb	Netcostbenefitofoperationofotherrealestateowned Netcostbenefitofoperationofotherrealestateowned	1218000	USD
CY2017	colb	Netcostbenefitofoperationofotherrealestateowned Netcostbenefitofoperationofotherrealestateowned	468000	USD
CY2019	us-gaap	Other Noninterest Expense OtherNoninterestExpense	34152000	USD
CY2018	us-gaap	Noninterest Expense NoninterestExpense	340490000	USD
CY2018	us-gaap	Other Noninterest Expense OtherNoninterestExpense	37024000	USD
CY2017	us-gaap	Noninterest Expense NoninterestExpense	291017000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	241611000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	211836000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	177983000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	47160000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	38954000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	65155000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	194451000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	172882000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	112828000	USD
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.68
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.36
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.86
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.68
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.36
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.86
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	71999000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	72385000	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	59882000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	72032000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	72390000	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	59888000	shares
CY2019	us-gaap	Net Income Loss NetIncomeLoss	194451000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	172882000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	112828000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	67802000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-13425000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-3391000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	1636000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	81000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-7000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	66166000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-13506000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-3384000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Reclassification Adjustments Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeReclassificationAdjustmentsNetOfTax	2042000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Reclassification Adjustments Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeReclassificationAdjustmentsNetOfTax	-24000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Reclassification Adjustments Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeReclassificationAdjustmentsNetOfTax	-4017000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	245000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	245000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	223000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-4240000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	1797000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-269000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	11760000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	0	USD
CY2017	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax	-457000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax	0	USD
CY2017	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	11303000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	0	USD
CY2017	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	75672000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-13237000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	856000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	270123000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	159645000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	113684000	USD
CY2016Q4	us-gaap	Stockholders Equity StockholdersEquity	1251012000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	112828000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	856000	USD
CY2017	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	636385000	USD
CY2017	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	1980000	USD
CY2017	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	7745000	USD
CY2017	us-gaap	Conversion Of Stock Amount Issued1 ConversionOfStockAmountIssued1	0	USD
CY2017	colb	Stock Adjustment Value Deferred Compensation StockAdjustmentValueDeferredCompensation	1000	USD
CY2017	colb	Stock Adjustment Value Deferred Compensation StockAdjustmentValueDeferredCompensation	1000	USD
CY2017	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	2299000	USD
CY2017	us-gaap	Stock Redeemed Or Called During Period Value StockRedeemedOrCalledDuringPeriodValue	7345000	USD
CY2017	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	51308000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	1949922000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	172882000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-13237000	USD
CY2018	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	1857000	USD
CY2018	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	8354000	USD
CY2018	colb	Stock Adjustment Value Deferred Compensation StockAdjustmentValueDeferredCompensation	7000	USD
CY2018	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	2677000	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	83459000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	2033649000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	194451000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	75672000	USD
CY2019	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	2025000	USD
CY2019	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	9271000	USD
CY2019	colb	Stock Adjustment Value Deferred Compensation StockAdjustmentValueDeferredCompensation	3000	USD
CY2019	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	2792000	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	102265000	USD
CY2019	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	50834000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	2159962000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	194451000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	172882000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	112828000	USD
CY2019	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3493000	USD
CY2018	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	14769000	USD
CY2017	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	8631000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	9271000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	8354000	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	7745000	USD
CY2019	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	34213000	USD
CY2018	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	32971000	USD
CY2017	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	31101000	USD
CY2019	us-gaap	Available For Sale Securities Gross Realized Gain Loss Net AvailableForSaleSecuritiesGrossRealizedGainLossNet	2132000	USD
CY2018	us-gaap	Available For Sale Securities Gross Realized Gain Loss Net AvailableForSaleSecuritiesGrossRealizedGainLossNet	-89000	USD
CY2017	us-gaap	Available For Sale Securities Gross Realized Gain Loss Net AvailableForSaleSecuritiesGrossRealizedGainLossNet	-11000	USD
CY2019	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	7317000	USD
CY2018	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	-316000	USD
CY2017	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	139000	USD
CY2019	colb	Netgainonsaleandvaluationadjustmentsof Oreo NetgainonsaleandvaluationadjustmentsofOREO	602000	USD
CY2018	colb	Netgainonsaleandvaluationadjustmentsof Oreo NetgainonsaleandvaluationadjustmentsofOREO	-1218000	USD
CY2017	colb	Netgainonsaleandvaluationadjustmentsof Oreo NetgainonsaleandvaluationadjustmentsofOREO	-495000	USD
CY2019	colb	Gainonsaleofmerchantcardservicesportfolio Gainonsaleofmerchantcardservicesportfolio	0	USD
CY2018	colb	Gainonsaleofmerchantcardservicesportfolio Gainonsaleofmerchantcardservicesportfolio	0	USD
CY2017	colb	Gainonsaleofmerchantcardservicesportfolio Gainonsaleofmerchantcardservicesportfolio	14000000	USD
CY2019	us-gaap	Gain Loss On Sale Of Insurance Block GainLossOnSaleOfInsuranceBlock	3051000	USD
CY2018	us-gaap	Gain Loss On Sale Of Insurance Block GainLossOnSaleOfInsuranceBlock	0	USD
CY2017	us-gaap	Gain Loss On Sale Of Insurance Block GainLossOnSaleOfInsuranceBlock	4193000	USD
CY2019	colb	Fdi Closssharingagreementearlyterminationpretaxcharge FDIClosssharingagreementearlyterminationpretaxcharge	0	USD
CY2018	colb	Fdi Closssharingagreementearlyterminationpretaxcharge FDIClosssharingagreementearlyterminationpretaxcharge	0	USD
CY2017	colb	Fdi Closssharingagreementearlyterminationpretaxcharge FDIClosssharingagreementearlyterminationpretaxcharge	2409000	USD
CY2019	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	210484000	USD
CY2018	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	133945000	USD
CY2017	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	133460000	USD
CY2019	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	196615000	USD
CY2018	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	135862000	USD
CY2017	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	133540000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	330000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	108000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	22431000	USD
CY2019	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	1516000	USD
CY2018	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	4442000	USD
CY2017	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	2980000	USD
CY2019	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	632000	USD
CY2018	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	164000	USD
CY2017	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	131000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	23464000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-2176000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	25471000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	14308000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	6679000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-10554000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	204747000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	237201000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	128525000	USD
CY2019	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	291857000	USD
CY2018	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	-2069000	USD
CY2017	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	273927000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	1196895000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	965585000	USD
CY2017	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	355607000	USD
CY2019	us-gaap	Payments To Acquire Loans Held For Investment PaymentsToAcquireLoansHeldForInvestment	57075000	USD
CY2018	us-gaap	Payments To Acquire Loans Held For Investment PaymentsToAcquireLoansHeldForInvestment	46969000	USD
CY2017	us-gaap	Payments To Acquire Loans Held For Investment PaymentsToAcquireLoansHeldForInvestment	0	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	8447000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	11328000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	6495000	USD
CY2019	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	273800000	USD
CY2018	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	197440000	USD
CY2017	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	92040000	USD
CY2019	colb	Proceedsfrom Fdi Cforreimbursementonlosssharingasset ProceedsfromFDICforreimbursementonlosssharingasset	0	USD
CY2018	colb	Proceedsfrom Fdi Cforreimbursementonlosssharingasset ProceedsfromFDICforreimbursementonlosssharingasset	0	USD
CY2017	colb	Proceedsfrom Fdi Cforreimbursementonlosssharingasset ProceedsfromFDICforreimbursementonlosssharingasset	26000	USD
CY2019	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	259554000	USD
CY2018	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	32330000	USD
CY2017	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	30403000	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Equity ProceedsFromSaleOfAvailableForSaleSecuritiesEquity	0	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities Equity ProceedsFromSaleOfAvailableForSaleSecuritiesEquity	4808000	USD
CY2017	us-gaap	Proceeds From Sale Of Available For Sale Securities Equity ProceedsFromSaleOfAvailableForSaleSecuritiesEquity	0	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	428025000	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	465747000	USD
CY2017	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	283874000	USD
CY2019	colb	Proceeds From Sales Of Loans Held For Investment And Other Assets ProceedsFromSalesOfLoansHeldForInvestmentAndOtherAssets	8634000	USD
CY2018	colb	Proceeds From Sales Of Loans Held For Investment And Other Assets ProceedsFromSalesOfLoansHeldForInvestmentAndOtherAssets	16030000	USD
CY2017	colb	Proceeds From Sales Of Loans Held For Investment And Other Assets ProceedsFromSalesOfLoansHeldForInvestmentAndOtherAssets	12422000	USD
CY2019	colb	Proceedsfromsaleofmerchantcardservicesportfolio Proceedsfromsaleofmerchantcardservicesportfolio	0	USD
CY2018	colb	Proceedsfromsaleofmerchantcardservicesportfolio Proceedsfromsaleofmerchantcardservicesportfolio	0	USD
CY2017	colb	Proceedsfromsaleofmerchantcardservicesportfolio Proceedsfromsaleofmerchantcardservicesportfolio	14000000	USD
CY2019	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	251640000	USD
CY2018	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	181920000	USD
CY2017	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	98924000	USD
CY2019	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	6506000	USD
CY2018	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	7261000	USD
CY2017	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	2590000	USD
CY2019	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	8265000	USD
CY2018	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	5074000	USD
CY2017	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	10745000	USD
CY2019	colb	Paymentfromto Fdi Ctoterminatelosssharingagreements PaymentfromtoFDICtoterminatelosssharingagreements	0	USD
CY2018	colb	Paymentfromto Fdi Ctoterminatelosssharingagreements PaymentfromtoFDICtoterminatelosssharingagreements	0	USD
CY2017	colb	Paymentfromto Fdi Ctoterminatelosssharingagreements PaymentfromtoFDICtoterminatelosssharingagreements	-4666000	USD
CY2019	colb	Paymentto Fdic Relatedto Loss Sharing Asset PaymenttoFDICRelatedtoLossSharingAsset	0	USD
CY2018	colb	Paymentto Fdic Relatedto Loss Sharing Asset PaymenttoFDICRelatedtoLossSharingAsset	0	USD
CY2017	colb	Paymentto Fdic Relatedto Loss Sharing Asset PaymenttoFDICRelatedtoLossSharingAsset	210000	USD
CY2019	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	0	USD
CY2018	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	0	USD
CY2017	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	80472000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-865450000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-506083000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-199489000	USD
CY2019	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	226958000	USD
CY2018	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	-73591000	USD
CY2017	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	353797000	USD
CY2019	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	3343000	USD
CY2018	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	7035000	USD
CY2017	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	-3380000	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	2025000	USD
CY2018	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1857000	USD
CY2017	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1980000	USD
CY2019	us-gaap	Proceeds From Federal Home Loan Bank Advances ProceedsFromFederalHomeLoanBankAdvances	6845000000	USD
CY2018	us-gaap	Proceeds From Federal Home Loan Bank Advances ProceedsFromFederalHomeLoanBankAdvances	4936000000	USD
CY2017	us-gaap	Proceeds From Federal Home Loan Bank Advances ProceedsFromFederalHomeLoanBankAdvances	2301000000	USD
CY2019	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	36000000	USD
CY2018	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	5010000	USD
CY2017	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	10000	USD
CY2019	us-gaap	Proceeds From Other Debt ProceedsFromOtherDebt	100000	USD
CY2018	us-gaap	Proceeds From Other Debt ProceedsFromOtherDebt	0	USD
CY2017	us-gaap	Proceeds From Other Debt ProceedsFromOtherDebt	0	USD
CY2019	us-gaap	Payments For Federal Home Loan Bank Advances PaymentsForFederalHomeLoanBankAdvances	6291000000	USD
CY2018	us-gaap	Payments For Federal Home Loan Bank Advances PaymentsForFederalHomeLoanBankAdvances	4548000000	USD
CY2017	us-gaap	Payments For Federal Home Loan Bank Advances PaymentsForFederalHomeLoanBankAdvances	2397000000	USD
CY2019	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	36000000	USD
CY2018	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	5010000	USD
CY2017	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	10000	USD
CY2019	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	100000	USD
CY2018	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	0	USD
CY2017	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	0	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	101911000	USD
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	83440000	USD
CY2017	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	51308000	USD
CY2019	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	USD
CY2018	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	8248000	USD
CY2017	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	6186000	USD
CY2019	colb	Repaymentoftermrepurchaseagreement Repaymentoftermrepurchaseagreement	0	USD
CY2018	colb	Repaymentoftermrepurchaseagreement Repaymentoftermrepurchaseagreement	25000000	USD
CY2017	colb	Repaymentoftermrepurchaseagreement Repaymentoftermrepurchaseagreement	0	USD
CY2019	us-gaap	Payments For Repurchase Of Equity PaymentsForRepurchaseOfEquity	0	USD
CY2018	us-gaap	Payments For Repurchase Of Equity PaymentsForRepurchaseOfEquity	0	USD
CY2017	us-gaap	Payments For Repurchase Of Equity PaymentsForRepurchaseOfEquity	7345000	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	50834000	USD
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	USD
CY2017	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	USD
CY2019	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	2792000	USD
CY2018	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	2677000	USD
CY2017	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	2299000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	630789000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	203936000	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	189259000	USD
CY2019	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-29914000	USD
CY2018	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-64946000	USD
CY2017	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	118295000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	277587000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	342533000	USD
CY2016Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	224238000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	247673000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	277587000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	342533000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	35916000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	18066000	USD
CY2017	us-gaap	Interest Paid Net InterestPaidNet	6626000	USD
CY2019	us-gaap	Income Taxes Paid IncomeTaxesPaid	47375000	USD
CY2018	us-gaap	Income Taxes Paid IncomeTaxesPaid	24067000	USD
CY2017	us-gaap	Income Taxes Paid IncomeTaxesPaid	59071000	USD
CY2019	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	386000	USD
CY2018	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	1200000	USD
CY2017	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	106000	USD
CY2019	us-gaap	Stock Issued1 StockIssued1	0	USD
CY2018	us-gaap	Stock Issued1 StockIssued1	0	USD
CY2017	us-gaap	Stock Issued1 StockIssued1	636385000	USD
CY2019	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	451000	USD
CY2018	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	195000	USD
CY2017	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	0	USD
CY2019	colb	Changeindividendspayableonunvestedshares Changeindividendspayableonunvestedshares	354000	USD
CY2018	colb	Changeindividendspayableonunvestedshares Changeindividendspayableonunvestedshares	19000	USD
CY2017	colb	Changeindividendspayableonunvestedshares Changeindividendspayableonunvestedshares	0	USD
CY2019Q4	colb	Number Of Branch Locations NumberOfBranchLocations	146
CY2019Q4	colb	Fhl Bmembershipstockpurchaserequirementcap FHLBmembershipstockpurchaserequirementcap	10000000	USD
CY2019Q4	colb	Federal Home Loan Bankstockparvalue FederalHomeLoanBankstockparvalue	100	USD
CY2019Q4	colb	Loans And Leases Receivable Nonaccrual Loans Considered Impaired LoansAndLeasesReceivableNonaccrualLoansConsideredImpaired	500000	USD
CY2019Q4	colb	Loans And Leases Receivable Loans Evaluated For Impairment On Quarterly Basis Outstanding LoansAndLeasesReceivableLoansEvaluatedForImpairmentOnQuarterlyBasisOutstanding	500000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Policy For Uncollectible Amounts FinancingReceivableAllowanceForCreditLossesPolicyForUncollectibleAmounts	<div style="line-height:120%;padding-top:12px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-style:italic;">Adoption of Allowance for Credit Losses - ASC 326</span></div><div style="line-height:120%;padding-top:12px;text-indent:30px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">In accordance with ASU 2016-13, the Company was required to adopt ASC 326 as of January 1, 2020. The allowance for credit losses under ASC 326 is an accounting estimate of expected losses over the contractual life of assets carried at amortized cost within the Company’s loan portfolio at the balance sheet date. The ASU requires a financial asset (or group of financial assets) measured at amortized cost to be presented at the net amount expected to be collected. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset to present the net carrying value at the amount expected to be collected on the financial asset.</span></div><div style="line-height:120%;padding-top:12px;text-indent:30px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">The quantitative allowance is calculated using a discounted cash flow approach with a probability of default methodology. The probability of default is an assumption derived from regression models which determines the relationship between historical defaults and certain economic variables. The Company determines a reasonable and supportable forecast and applies that forecast to the model to determine defaults over the forecast period. Following the forecast period, the economic variables used to calculate the probability of default revert to a historical average. Other assumptions relevant to the discounted cash flow model to derive the quantitative allowance include the loss given default, which is the estimate of loss for a defaulted loan, and the discount rate applied to future cash flows. The model calculates the net present value of each loan using both the contractual and expected cash flows, respectively.</span></div><div style="line-height:120%;padding-top:12px;text-indent:30px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">In addition to the quantitative portion of the allowance for credit losses, the Company also considers the effects of the following qualitative factors in its calculation of expected losses in the loan portfolio:</span></div><table cellpadding="0" cellspacing="0" style="padding-top:12px;font-family:Times New Roman; font-size:10pt;"><tr><td style="width:66px;"/><td/></tr><tr><td style="vertical-align:top"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><span style="font-family:inherit;font-size:10pt;">•</span></div></td><td style="vertical-align:top;"><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Economic and business conditions;</span></div></td></tr></table><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman; font-size:10pt;"><tr><td style="width:66px;"/><td/></tr><tr><td style="vertical-align:top"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><span style="font-family:inherit;font-size:10pt;">•</span></div></td><td style="vertical-align:top;"><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Concentration of credit;</span></div></td></tr></table><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman; font-size:10pt;"><tr><td style="width:66px;"/><td/></tr><tr><td style="vertical-align:top"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><span style="font-family:inherit;font-size:10pt;">•</span></div></td><td style="vertical-align:top;"><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Lending management and staff;</span></div></td></tr></table><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman; font-size:10pt;"><tr><td style="width:66px;"/><td/></tr><tr><td style="vertical-align:top"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><span style="font-family:inherit;font-size:10pt;">•</span></div></td><td style="vertical-align:top;"><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Lending policies and procedures;</span></div></td></tr></table><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman; font-size:10pt;"><tr><td style="width:66px;"/><td/></tr><tr><td style="vertical-align:top"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><span style="font-family:inherit;font-size:10pt;">•</span></div></td><td style="vertical-align:top;"><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Loss and recovery trends;</span></div></td></tr></table><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman; font-size:10pt;"><tr><td style="width:66px;"/><td/></tr><tr><td style="vertical-align:top"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><span style="font-family:inherit;font-size:10pt;">•</span></div></td><td style="vertical-align:top;"><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Nature and volume of the portfolio;</span></div></td></tr></table><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman; font-size:10pt;"><tr><td style="width:66px;"/><td/></tr><tr><td style="vertical-align:top"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><span style="font-family:inherit;font-size:10pt;">•</span></div></td><td style="vertical-align:top;"><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Trends in problem loans, loan delinquencies and nonaccrual loans;</span></div></td></tr></table><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman; font-size:10pt;"><tr><td style="width:66px;"/><td/></tr><tr><td style="vertical-align:top"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><span style="font-family:inherit;font-size:10pt;">•</span></div></td><td style="vertical-align:top;"><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Quality of internal loan review; and</span></div></td></tr></table><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman; font-size:10pt;"><tr><td style="width:66px;"/><td/></tr><tr><td style="vertical-align:top"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><span style="font-family:inherit;font-size:10pt;">•</span></div></td><td style="vertical-align:top;"><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">External factors.</span></div></td></tr></table><div style="line-height:120%;padding-top:12px;text-indent:32px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">These qualitative factors are based in quantitative factors but also include a high degree of subjectivity and changes in any of the factors could have a significant impact on our calculation of the allowance. </span></div><div style="line-height:120%;padding-top:12px;text-indent:32px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Loans for which repayment is expected to be provided substantially through the operation or sale of collateral are considered collateral-dependent. The allowance for credit losses for collateral-dependent loans is measured on the basis of the fair value of the collateral when foreclosure is probable.</span></div>
CY2019Q4	colb	Number Of Issuances Of Securities Exceeding Shareholders Equity Threshold NumberOfIssuancesOfSecuritiesExceedingShareholdersEquityThreshold	0
CY2019Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	3703096000	USD
CY2019Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	63486000	USD
CY2019Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	20440000	USD
CY2019Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	3746142000	USD
CY2018Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	3210615000	USD
CY2018Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	12799000	USD
CY2018Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	55966000	USD
CY2018Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	3167448000	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	259554000	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	32330000	USD
CY2017	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	30403000	USD
CY2019	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	3357000	USD
CY2018	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	235000	USD
CY2017	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	111000	USD
CY2019	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	1225000	USD
CY2018	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	129000	USD
CY2017	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	122000	USD
CY2019	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	0	USD
CY2018	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	-195000	USD
CY2017	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	0	USD
CY2019	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	2132000	USD
CY2018	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-89000	USD
CY2017	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-11000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	77363000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	77538000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	416556000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	421363000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	2007225000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	2041751000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	1201952000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	1205490000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	3703096000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	3746142000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Restricted DebtSecuritiesAvailableForSaleRestricted	588573000	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Restricted DebtSecuritiesAvailableForSaleRestricted	467138000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	1157774000	USD
CY2019Q4	colb	Availableforsale Securities Continuous Unrealized Loss Position Lessthan12 Months Aggregate Loss Instant AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAggregateLossInstant	13446000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	521420000	USD
CY2019Q4	colb	Availableforsale Securities Continuous Unrealized Loss Position12 Monthsor Longer Aggregate Lossinstant AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAggregateLossinstant	6994000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	1679194000	USD
CY2019Q4	colb	Availableforsale Securities Continuous Unrealized Loss Position Aggregate Lossinstant AvailableforsaleSecuritiesContinuousUnrealizedLossPositionAggregateLossinstant	20440000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	276306000	USD
CY2018Q4	colb	Availableforsale Securities Continuous Unrealized Loss Position Lessthan12 Months Aggregate Loss Instant AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAggregateLossInstant	1598000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	1873565000	USD
CY2018Q4	colb	Availableforsale Securities Continuous Unrealized Loss Position12 Monthsor Longer Aggregate Lossinstant AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAggregateLossinstant	54368000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	2149871000	USD
CY2018Q4	colb	Availableforsale Securities Continuous Unrealized Loss Position Aggregate Lossinstant AvailableforsaleSecuritiesContinuousUnrealizedLossPositionAggregateLossinstant	55966000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	34315000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	42194000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	8743465000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	8391511000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	83968000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	83369000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	8659497000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	8308142000	USD
CY2019Q4	us-gaap	Loans Receivable Held For Sale Net Not Part Of Disposal Group LoansReceivableHeldForSaleNetNotPartOfDisposalGroup	17718000	USD
CY2018Q4	us-gaap	Loans Receivable Held For Sale Net Not Part Of Disposal Group LoansReceivableHeldForSaleNetNotPartOfDisposalGroup	3849000	USD
CY2019	us-gaap	Loans And Leases Receivable Impaired Interest Lost On Nonaccrual Loans LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans	2000000.0	USD
CY2018	us-gaap	Loans And Leases Receivable Impaired Interest Lost On Nonaccrual Loans LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans	3600000	USD
CY2017	us-gaap	Loans And Leases Receivable Impaired Interest Lost On Nonaccrual Loans LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans	2400000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	0	USD
CY2019Q4	colb	Loans And Leases Receivable Nonaccrual Of Interest Commitments Of Additional Funds LoansAndLeasesReceivableNonaccrualOfInterestCommitmentsOfAdditionalFunds	2000000.0	USD
CY2018Q4	colb	Loans And Leases Receivable Nonaccrual Of Interest Commitments Of Additional Funds LoansAndLeasesReceivableNonaccrualOfInterestCommitmentsOfAdditionalFunds	2100000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	33060000	USD
CY2019Q4	colb	Financing Receivable Unpaid Principal Balance Nonaccrual Status FinancingReceivableUnpaidPrincipalBalanceNonaccrualStatus	45209000	USD
CY2018Q4	colb	Financing Receivable Recorded Investment Gross Nonaccrual Status FinancingReceivableRecordedInvestmentGrossNonaccrualStatus	54842000	USD
CY2018Q4	colb	Financing Receivable Unpaid Principal Balance Nonaccrual Status FinancingReceivableUnpaidPrincipalBalanceNonaccrualStatus	65358000	USD
CY2019Q4	colb	Financing Receivable Modifications Additional Commitment To Lend FinancingReceivableModificationsAdditionalCommitmentToLend	1100000	USD
CY2018Q4	colb	Financing Receivable Modifications Additional Commitment To Lend FinancingReceivableModificationsAdditionalCommitmentToLend	2100000	USD
CY2019	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	1
CY2019	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	26000	USD
CY2018Q4	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield	21949000	USD
CY2017Q4	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield	31176000	USD
CY2016Q4	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield	45191000	USD
CY2019	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Accretion CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAccretion	6053000	USD
CY2018	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Accretion CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAccretion	8194000	USD
CY2017	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Accretion CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAccretion	12357000	USD
CY2019	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Disposals Of Loans CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldDisposalsOfLoans	-46000	USD
CY2018	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Disposals Of Loans CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldDisposalsOfLoans	387000	USD
CY2017	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Disposals Of Loans CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldDisposalsOfLoans	158000	USD
CY2019	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Reclassifications To From Nonaccretable Difference CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldReclassificationsToFromNonaccretableDifference	3719000	USD
CY2018	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Reclassifications To From Nonaccretable Difference CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldReclassificationsToFromNonaccretableDifference	-646000	USD
CY2017	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Reclassifications To From Nonaccretable Difference CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldReclassificationsToFromNonaccretableDifference	-1500000	USD
CY2019Q4	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield	19661000	USD
CY2018Q4	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield	21949000	USD
CY2017Q4	us-gaap	Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield	31176000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	83369000	USD
CY2019	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	15215000	USD
CY2019	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	12321000	USD
CY2019	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3493000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	83968000	USD
CY2019Q4	colb	Loan And Lease Losses Specific Reserve LoanAndLeaseLossesSpecificReserve	461000	USD
CY2019Q4	colb	Loan And Lease Losses General Allocation LoanAndLeaseLossesGeneralAllocation	83507000	USD
CY2017Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	75646000	USD
CY2018	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	18555000	USD
CY2018	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	11509000	USD
CY2018	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	14769000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	83369000	USD
CY2018Q4	colb	Loan And Lease Losses Specific Reserve LoanAndLeaseLossesSpecificReserve	2132000	USD
CY2018Q4	colb	Loan And Lease Losses General Allocation LoanAndLeaseLossesGeneralAllocation	81237000	USD
CY2016Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	70043000	USD
CY2017	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	16660000	USD
CY2017	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	13632000	USD
CY2017	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	8631000	USD
CY2017Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	75646000	USD
CY2017Q4	colb	Loan And Lease Losses Specific Reserve LoanAndLeaseLossesSpecificReserve	2360000	USD
CY2017Q4	colb	Loan And Lease Losses General Allocation LoanAndLeaseLossesGeneralAllocation	73286000	USD
CY2018Q4	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	4330000	USD
CY2017Q4	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	3130000	USD
CY2016Q4	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	2705000	USD
CY2019	colb	Allowance For Loan And Lease Losses Net Changes In Unfunded Commitments And Letters Of Credit Allowance AllowanceForLoanAndLeaseLossesNetChangesInUnfundedCommitmentsAndLettersOfCreditAllowance	-900000	USD
CY2018	colb	Allowance For Loan And Lease Losses Net Changes In Unfunded Commitments And Letters Of Credit Allowance AllowanceForLoanAndLeaseLossesNetChangesInUnfundedCommitmentsAndLettersOfCreditAllowance	1200000	USD
CY2017	colb	Allowance For Loan And Lease Losses Net Changes In Unfunded Commitments And Letters Of Credit Allowance AllowanceForLoanAndLeaseLossesNetChangesInUnfundedCommitmentsAndLettersOfCreditAllowance	425000	USD
CY2019Q4	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	3430000	USD
CY2018Q4	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	4330000	USD
CY2017Q4	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	3130000	USD
CY2018Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	6019000	USD
CY2017Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	13298000	USD
CY2019	colb	Real Estate Acquired Through Foreclosure Transfers In Net Of Write Downs RealEstateAcquiredThroughForeclosureTransfersInNetOfWriteDowns	386000	USD
CY2018	colb	Real Estate Acquired Through Foreclosure Transfers In Net Of Write Downs RealEstateAcquiredThroughForeclosureTransfersInNetOfWriteDowns	1200000	USD
CY2019	colb	Transfer Other Real Estate Write Down TransferOtherRealEstateWriteDown	195000	USD
CY2018	colb	Transfer Other Real Estate Write Down TransferOtherRealEstateWriteDown	698000	USD
CY2019	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	6455000	USD
CY2018	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	7261000	USD
CY2019	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	797000	USD
CY2018	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-520000	USD
CY2019Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	552000	USD
CY2018Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	6019000	USD
CY2019Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	875000	USD
CY2019Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	35458000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	243329000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	243095000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	77921000	USD
CY2018Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	74307000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	165408000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	168788000	USD
CY2019	us-gaap	Depreciation And Amortization DepreciationAndAmortization	10300000	USD
CY2018	us-gaap	Depreciation And Amortization DepreciationAndAmortization	10400000	USD
CY2017	us-gaap	Depreciation And Amortization DepreciationAndAmortization	9800000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	765842000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	765842000	USD
CY2016Q4	us-gaap	Goodwill Goodwill	382762000	USD
CY2019	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	0	USD
CY2018	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	0	USD
CY2017	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	383080000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	765842000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	765842000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	765842000	USD
CY2019Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	919000	USD
CY2018Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	919000	USD
CY2017Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	919000	USD
CY2018Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	45937000	USD
CY2017Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	58173000	USD
CY2019Q4	colb	Goodwill And Intangible Assets Total GoodwillAndIntangibleAssetsTotal	801300000	USD
CY2018Q4	colb	Goodwill And Intangible Assets Total GoodwillAndIntangibleAssetsTotal	811779000	USD
CY2017Q4	colb	Goodwill And Intangible Assets Total GoodwillAndIntangibleAssetsTotal	824015000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	57226000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	63030000	USD
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P7Y8M12D
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.030
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	11200000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	20600000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	10851000	USD
CY2019	us-gaap	Variable Lease Cost VariableLeaseCost	1805000	USD
CY2019	us-gaap	Sublease Income SubleaseIncome	1182000	USD
CY2019	us-gaap	Lease Cost LeaseCost	11474000	USD
CY2018	us-gaap	Operating Leases Rent Expense Sublease Rentals1 OperatingLeasesRentExpenseSubleaseRentals1	1200000	USD
CY2017	us-gaap	Operating Leases Rent Expense Sublease Rentals1 OperatingLeasesRentExpenseSubleaseRentals1	791000	USD
CY2018	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	9600000	USD
CY2017	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	7900000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	11105000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	11126000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	10689000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	9476000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	6980000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	21866000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	71242000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	8212000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	63030000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	10947000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	9766000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	8729000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	8102000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	6796000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	18703000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	63043000	USD
CY2019Q4	us-gaap	Noninterest Bearing Deposit Liabilities Domestic NoninterestBearingDepositLiabilitiesDomestic	5328146000	USD
CY2018Q4	us-gaap	Noninterest Bearing Deposit Liabilities Domestic NoninterestBearingDepositLiabilitiesDomestic	5227216000	USD
CY2019Q4	us-gaap	Deposits Money Market Deposits DepositsMoneyMarketDeposits	2322644000	USD
CY2018Q4	us-gaap	Deposits Money Market Deposits DepositsMoneyMarketDeposits	2294125000	USD
CY2019Q4	us-gaap	Interest Bearing Domestic Deposit Demand InterestBearingDomesticDepositDemand	1150437000	USD
CY2018Q4	us-gaap	Interest Bearing Domestic Deposit Demand InterestBearingDomesticDepositDemand	1084863000	USD
CY2019Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	882050000	USD
CY2018Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	889849000	USD
CY2019Q4	colb	Interestbearingpublicfundsotherthancertificatesofdeposit Interestbearingpublicfundsotherthancertificatesofdeposit	301203000	USD
CY2018Q4	colb	Interestbearingpublicfundsotherthancertificatesofdeposit Interestbearingpublicfundsotherthancertificatesofdeposit	233938000	USD
CY2019Q4	us-gaap	Time Deposits Less Than100000 TimeDepositsLessThan100000	218764000	USD
CY2018Q4	us-gaap	Time Deposits Less Than100000 TimeDepositsLessThan100000	243849000	USD
CY2019Q4	us-gaap	Time Deposits100000 Or More TimeDeposits100000OrMore	151995000	USD
CY2018Q4	us-gaap	Time Deposits100000 Or More TimeDeposits100000OrMore	89473000	USD
CY2019Q4	colb	Certificates Of Deposit Insured By Cdars CertificatesOfDepositInsuredByCdars	17065000	USD
CY2018Q4	colb	Certificates Of Deposit Insured By Cdars CertificatesOfDepositInsuredByCdars	23580000	USD
CY2019Q4	colb	Otherbrokeredcertificatesofdeposit Otherbrokeredcertificatesofdeposit	12259000	USD
CY2018Q4	colb	Otherbrokeredcertificatesofdeposit Otherbrokeredcertificatesofdeposit	57930000	USD
CY2019Q4	colb	Brokered Money Market Accounts BrokeredMoneyMarketAccounts	300158000	USD
CY2018Q4	colb	Brokered Money Market Accounts BrokeredMoneyMarketAccounts	313692000	USD
CY2019Q4	colb	Core And Other Deposits CoreAndOtherDeposits	10684721000	USD
CY2018Q4	colb	Core And Other Deposits CoreAndOtherDeposits	10458515000	USD
CY2019Q4	colb	Deposits Valuation Adjustment From Acquisition Accounting DepositsValuationAdjustmentFromAcquisitionAccounting	-13000	USD
CY2018Q4	colb	Deposits Valuation Adjustment From Acquisition Accounting DepositsValuationAdjustmentFromAcquisitionAccounting	-389000	USD
CY2019Q4	us-gaap	Deposits Deposits	10684708000	USD
CY2018Q4	us-gaap	Deposits Deposits	10458126000	USD
CY2019Q4	us-gaap	Deposit Liabilities Reclassified As Loans Receivable1 DepositLiabilitiesReclassifiedAsLoansReceivable1	3800000	USD
CY2018Q4	us-gaap	Deposit Liabilities Reclassified As Loans Receivable1 DepositLiabilitiesReclassifiedAsLoansReceivable1	4000000.0	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	313241000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	53679000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	19346000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	8060000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	5593000	USD
CY2019Q4	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	151000	USD
CY2019Q4	us-gaap	Time Deposits TimeDeposits	400070000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances General Debt Obligations Disclosures Maximum Amount Available FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable	1960000000	USD
CY2018Q4	us-gaap	Federal Home Loan Bank Advances General Debt Obligations Disclosures Maximum Amount Available FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable	1620000000	USD
CY2019Q4	colb	Federal Home Loan Bank Advances Maturities Summary By Interest Rate Type Fixed Rate Before Valuation Adjustment FederalHomeLoanBankAdvancesMaturitiesSummaryByInterestRateTypeFixedRateBeforeValuationAdjustment	953000000.0	USD
CY2018Q4	colb	Federal Home Loan Bank Advances Maturities Summary By Interest Rate Type Fixed Rate Before Valuation Adjustment FederalHomeLoanBankAdvancesMaturitiesSummaryByInterestRateTypeFixedRateBeforeValuationAdjustment	399000000.0	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	0.0182
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary By Interest Rate Type Fixed Rate Under One Year FederalHomeLoanBankAdvancesMaturitiesSummaryByInterestRateTypeFixedRateUnderOneYear	946000000	USD
CY2019Q4	colb	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate One To Five Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOneToFiveYearsFromBalanceSheetDate	0.0385
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary By Interest Rate Type Fixed Rate One To Five Years FederalHomeLoanBankAdvancesMaturitiesSummaryByInterestRateTypeFixedRateOneToFiveYears	2000000	USD
CY2019Q4	colb	Federal Home Loan Bank Advances Maturities Summary Average Interest Rate After Ten Years From Balance Sheet Date FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateAfterTenYearsFromBalanceSheetDate	0.0537
CY2019Q4	colb	Federal Home Loan Bank Advances Maturities Summary By Interest Rate Type Fixed Rate After Ten Years FederalHomeLoanBankAdvancesMaturitiesSummaryByInterestRateTypeFixedRateAfterTenYears	5000000	USD
CY2019Q4	colb	Federal Home Loan Bank Advances Maturities Summary By Interest Rate Type Fixed Rate Before Valuation Adjustment FederalHomeLoanBankAdvancesMaturitiesSummaryByInterestRateTypeFixedRateBeforeValuationAdjustment	953000000	USD
CY2019Q4	colb	Federal Home Loan Bank Fixed Rate Advances Valuation Adjustment From Acquisition Accounting FederalHomeLoanBankFixedRateAdvancesValuationAdjustmentFromAcquisitionAccounting	469000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Maturities Summary By Interest Rate Type Fixed Rate FederalHomeLoanBankAdvancesMaturitiesSummaryByInterestRateTypeFixedRate	953469000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Long Term FederalHomeLoanBankAdvancesLongTerm	953469000	USD
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Long Term FederalHomeLoanBankAdvancesLongTerm	399523000	USD
CY2017Q4	us-gaap	Federal Home Loan Bank Advances Long Term FederalHomeLoanBankAdvancesLongTerm	11579000	USD
CY2019	us-gaap	Federal Home Loan Bank Advances Activity For Year Average Balance Of Agreements Outstanding FederalHomeLoanBankAdvancesActivityForYearAverageBalanceOfAgreementsOutstanding	469983000	USD
CY2018	us-gaap	Federal Home Loan Bank Advances Activity For Year Average Balance Of Agreements Outstanding FederalHomeLoanBankAdvancesActivityForYearAverageBalanceOfAgreementsOutstanding	166563000	USD
CY2017	us-gaap	Federal Home Loan Bank Advances Activity For Year Average Balance Of Agreements Outstanding FederalHomeLoanBankAdvancesActivityForYearAverageBalanceOfAgreementsOutstanding	79788000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Activity For Year Maximum Outstanding At Any Month End FederalHomeLoanBankAdvancesActivityForYearMaximumOutstandingAtAnyMonthEnd	953469000	USD
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Activity For Year Maximum Outstanding At Any Month End FederalHomeLoanBankAdvancesActivityForYearMaximumOutstandingAtAnyMonthEnd	399523000	USD
CY2017Q4	us-gaap	Federal Home Loan Bank Advances Activity For Year Maximum Outstanding At Any Month End FederalHomeLoanBankAdvancesActivityForYearMaximumOutstandingAtAnyMonthEnd	317480000	USD
CY2019	us-gaap	Federal Home Loan Bank Advances Activity For Year Average Interest Rate For Year FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateForYear	0.0242
CY2018	us-gaap	Federal Home Loan Bank Advances Activity For Year Average Interest Rate For Year FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateForYear	0.0229
CY2017	us-gaap	Federal Home Loan Bank Advances Activity For Year Average Interest Rate For Year FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateForYear	0.0133
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Activity For Year Average Interest Rate At Period End FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateAtPeriodEnd	0.0184
CY2018Q4	us-gaap	Federal Home Loan Bank Advances Activity For Year Average Interest Rate At Period End FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateAtPeriodEnd	0.0268
CY2017Q4	us-gaap	Federal Home Loan Bank Advances Activity For Year Average Interest Rate At Period End FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateAtPeriodEnd	0.0408
CY2019	colb	Federal Reserve Bank Advances Activityfortheyearaveragebalanceofagreementsoutstanding FederalReserveBankAdvancesActivityfortheyearaveragebalanceofagreementsoutstanding	99000	USD
CY2018	colb	Federal Reserve Bank Advances Activityfortheyearaveragebalanceofagreementsoutstanding FederalReserveBankAdvancesActivityfortheyearaveragebalanceofagreementsoutstanding	14000	USD
CY2019Q4	colb	Federal Reserve Bank Advances Maximum Amount Available FederalReserveBankAdvancesMaximumAmountAvailable	209100000	USD
CY2018Q4	colb	Federal Reserve Bank Advances Maximum Amount Available FederalReserveBankAdvancesMaximumAmountAvailable	107100000	USD
CY2019	us-gaap	Subordinated Borrowing Interest Rate SubordinatedBorrowingInterestRate	0.05875
CY2019Q4	us-gaap	Line Of Credit Facility Maximum Borrowing Capacity LineOfCreditFacilityMaximumBorrowingCapacity	30000000.0	USD
CY2019Q4	us-gaap	Interest Rate Cash Flow Hedge Gain Loss To Be Reclassified During Next12 Months Net InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet	3200000	USD
CY2019	us-gaap	Gain Loss On Derivative Instruments Net Pretax GainLossOnDerivativeInstrumentsNetPretax	-1000	USD
CY2018	us-gaap	Gain Loss On Derivative Instruments Net Pretax GainLossOnDerivativeInstrumentsNetPretax	8000	USD
CY2017	us-gaap	Gain Loss On Derivative Instruments Net Pretax GainLossOnDerivativeInstrumentsNetPretax	16000	USD
CY2019	us-gaap	Unrealized Gain Loss On Interest Rate Cash Flow Hedges Pretax Accumulated Other Comprehensive Income Loss UnrealizedGainLossOnInterestRateCashFlowHedgesPretaxAccumulatedOtherComprehensiveIncomeLoss	15322000	USD
CY2018	us-gaap	Unrealized Gain Loss On Interest Rate Cash Flow Hedges Pretax Accumulated Other Comprehensive Income Loss UnrealizedGainLossOnInterestRateCashFlowHedgesPretaxAccumulatedOtherComprehensiveIncomeLoss	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	595000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	0	USD
CY2019Q4	colb	Repurchaseagreementsamountsoffsetinbalancesheet Repurchaseagreementsamountsoffsetinbalancesheet	0	USD
CY2019Q4	colb	Repurchaseagreementsnetamountpresentedinstatementoffinancialposition Repurchaseagreementsnetamountpresentedinstatementoffinancialposition	64437000	USD
CY2019Q4	us-gaap	Securities Sold Under Agreements To Repurchase Collateral Right To Reclaim Securities SecuritiesSoldUnderAgreementsToRepurchaseCollateralRightToReclaimSecurities	64437000	USD
CY2019Q4	colb	Securitiessoldunderagreementstorepurchaseamountnotoffset Securitiessoldunderagreementstorepurchaseamountnotoffset	0	USD
CY2018Q4	colb	Repurchaseagreementsamountsoffsetinbalancesheet Repurchaseagreementsamountsoffsetinbalancesheet	0	USD
CY2018Q4	colb	Repurchaseagreementsnetamountpresentedinstatementoffinancialposition Repurchaseagreementsnetamountpresentedinstatementoffinancialposition	61094000	USD
CY2018Q4	us-gaap	Securities Sold Under Agreements To Repurchase Collateral Right To Reclaim Securities SecuritiesSoldUnderAgreementsToRepurchaseCollateralRightToReclaimSecurities	61094000	USD
CY2018Q4	colb	Securitiessoldunderagreementstorepurchaseamountnotoffset Securitiessoldunderagreementstorepurchaseamountnotoffset	0	USD
CY2019Q4	us-gaap	Secured Borrowings Gross Including Not Subject To Master Netting Arrangement SecuredBorrowingsGrossIncludingNotSubjectToMasterNettingArrangement	64437000	USD
CY2019Q4	us-gaap	Secured Borrowings Gross Difference Amount SecuredBorrowingsGrossDifferenceAmount	0	USD
CY2019	colb	Discount On Common Stock Under Employee Stock Purchase Plan Percent DiscountOnCommonStockUnderEmployeeStockPurchasePlanPercent	0.10
CY2019	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	57201	shares
CY2019	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	2100000	USD
CY2018	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	50750	shares
CY2018	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	2000000.0	USD
CY2017	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	38387	shares
CY2017	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	1500000	USD
CY2019Q4	colb	Shares Available For Purchase Under Employee Stock Purchase Plan SharesAvailableForPurchaseUnderEmployeeStockPurchasePlan	303156	shares
CY2018Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	21287000	USD
CY2017Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	20553000	USD
CY2019	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	2663000	USD
CY2018	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	-31000	USD
CY2019	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	1930000	USD
CY2018	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	1701000	USD
CY2019	us-gaap	Defined Benefit Plan Benefit Obligation Benefits Paid DefinedBenefitPlanBenefitObligationBenefitsPaid	966000	USD
CY2018	us-gaap	Defined Benefit Plan Benefit Obligation Benefits Paid DefinedBenefitPlanBenefitObligationBenefitsPaid	936000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	24914000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	21287000	USD
CY2019Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.28
CY2019Q1	colb	Common Stock Special Cash Dividends Per Share Declared CommonStockSpecialCashDividendsPerShareDeclared	0.14
CY2019Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.28
CY2019Q2	colb	Common Stock Special Cash Dividends Per Share Declared CommonStockSpecialCashDividendsPerShareDeclared	0.14
CY2019Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.28
CY2019Q3	colb	Common Stock Special Cash Dividends Per Share Declared CommonStockSpecialCashDividendsPerShareDeclared	0
CY2019Q4	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.28
CY2019Q4	colb	Common Stock Special Cash Dividends Per Share Declared CommonStockSpecialCashDividendsPerShareDeclared	0
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.68
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.36
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.86
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	192921000	USD
CY2018	colb	Basic Earnings Allocated To Common Shareholders BasicEarningsAllocatedToCommonShareholders	170990000	USD
CY2017	colb	Basic Earnings Allocated To Common Shareholders BasicEarningsAllocatedToCommonShareholders	111324000	USD
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	71999000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	72385000	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	59882000	shares
CY2018	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	170990000	USD
CY2017	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	111324000	USD
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	71999000	shares
CY2019	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	33000	shares
CY2019	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	1500000	shares
CY2019	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	35.00
CY2019Q4	us-gaap	Stock Repurchase Program Remaining Number Of Shares Authorized To Be Repurchased StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased	1400000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	72385000	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	59882000	shares
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-35305000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	77520000	USD
CY2019	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	1848000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	75672000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	40367000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-22225000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	-13401000	USD
CY2018	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-164000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-13237000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-35305000	USD
CY2016Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-18999000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	626000	USD
CY2017	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-230000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	856000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-22225000	USD
CY2019Q4	us-gaap	Fair Value Liabilities Level1 To Level2 Transfers Amount FairValueLiabilitiesLevel1ToLevel2TransfersAmount	0	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	194451000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	172882000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	112828000	USD
CY2019	colb	Earningsallocatedtoparticipatingsecuritiespreferredshares Earningsallocatedtoparticipatingsecuritiespreferredshares	0	USD
CY2018	colb	Earningsallocatedtoparticipatingsecuritiespreferredshares Earningsallocatedtoparticipatingsecuritiespreferredshares	0	USD
CY2017	colb	Earningsallocatedtoparticipatingsecuritiespreferredshares Earningsallocatedtoparticipatingsecuritiespreferredshares	3000	USD
CY2019	colb	Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares	1530000	USD
CY2018	colb	Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares	1892000	USD
CY2017	colb	Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares	1501000	USD
CY2019	colb	Basic Earnings Allocated To Common Shareholders BasicEarningsAllocatedToCommonShareholders	192921000	USD
CY2018	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	5000	shares
CY2017	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	6000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	72032000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	72390000	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	59888000	shares
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.68
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.36
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.86
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	8000	shares
CY2018	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	4000	shares
CY2017	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	13000	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	3050000	shares
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	818755	shares
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	27.19
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	337384	shares
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	38.51
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	253509	shares
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	25.67
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	96924	shares
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	28.97
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	805706	shares
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	32.23
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	306592	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	41.47
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	237146	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	28.78
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	61012	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	35.92
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	814140	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	36.43
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	405516	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	35.08
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	268253	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	32.50
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	62386	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	37.12
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	889017	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	36.96
CY2019Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	23100000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	5446000	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	3016000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	46830000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P2Y8M12D
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	8700000	USD
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	6700000	USD
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	6500000	USD
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	5514	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	9.91
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	1187	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	9.91
CY2019	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	4327	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	9.91
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	0	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	108000	USD
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	29000	USD
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	67000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares	0	shares
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	9300000	USD
CY2018	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	8400000	USD
CY2017	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	7700000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	40471000	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	33400000	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	39708000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	6359000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	38846000	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	42724000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	60000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-291000	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	21524000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	270000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	399000	USD
CY2017	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	907000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	330000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	108000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	22431000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	47160000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	38954000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	65155000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	20489000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	20578000	USD
CY2019Q4	colb	Deferred Tax Assets Leasing Arrangements DeferredTaxAssetsLeasingArrangements	14776000	USD
CY2018Q4	colb	Deferred Tax Assets Leasing Arrangements DeferredTaxAssetsLeasingArrangements	0	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	11079000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	9501000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	2016000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	1850000	USD
CY2019Q4	colb	Deferred Tax Asset Other Real Estate Owned Costs DeferredTaxAssetOtherRealEstateOwnedCosts	0	USD
CY2018Q4	colb	Deferred Tax Asset Other Real Estate Owned Costs DeferredTaxAssetOtherRealEstateOwnedCosts	288000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	112000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	446000	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	10129000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	4136000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	5356000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	245000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	733000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	52853000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	48881000	USD
CY2019Q4	colb	Deferred Tax Liabilities Asset Purchase Tax Basis Difference DeferredTaxLiabilitiesAssetPurchaseTaxBasisDifference	7888000	USD
CY2018Q4	colb	Deferred Tax Liabilities Asset Purchase Tax Basis Difference DeferredTaxLiabilitiesAssetPurchaseTaxBasisDifference	7229000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	13415000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	0	USD
CY2019Q4	colb	Deferred Tax Liabilities Stock Dividends DeferredTaxLiabilitiesStockDividends	789000	USD
CY2018Q4	colb	Deferred Tax Liabilities Stock Dividends DeferredTaxLiabilitiesStockDividends	790000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Financing Costs DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts	4097000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Financing Costs DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts	4399000	USD
CY2019Q4	colb	Deferredtaxliabilitiesunrealizedgainsonavailableforsalesecurities Deferredtaxliabilitiesunrealizedgainsonavailableforsalesecurities	10091000	USD
CY2018Q4	colb	Deferredtaxliabilitiesunrealizedgainsonavailableforsalesecurities Deferredtaxliabilitiesunrealizedgainsonavailableforsalesecurities	0	USD
CY2019Q4	colb	Deferredtaxliabilitiespurchaseaccounting Deferredtaxliabilitiespurchaseaccounting	8946000	USD
CY2018Q4	colb	Deferredtaxliabilitiespurchaseaccounting Deferredtaxliabilitiespurchaseaccounting	9245000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	3152000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	2609000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Derivatives DeferredTaxLiabilitiesDerivatives	3452000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Derivatives DeferredTaxLiabilitiesDerivatives	0	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	100000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	195000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	51930000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	24467000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	923000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	24414000	USD
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	50738000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	44485000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2017	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	62262000	USD
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2019	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	6771000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	-0.03
CY2018	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	6423000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	-0.03
CY2017	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	8485000	USD
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	-0.05
CY2019	colb	Income Tax Reconciliation Life Insurance Proceeds IncomeTaxReconciliationLifeInsuranceProceeds	1963000	USD
CY2019	colb	Effective Income Tax Rate Reconciliation Life Insurance Proceeds EffectiveIncomeTaxRateReconciliationLifeInsuranceProceeds	-0.01
CY2018	colb	Income Tax Reconciliation Life Insurance Proceeds IncomeTaxReconciliationLifeInsuranceProceeds	1261000	USD
CY2018	colb	Effective Income Tax Rate Reconciliation Life Insurance Proceeds EffectiveIncomeTaxRateReconciliationLifeInsuranceProceeds	-0.01
CY2017	colb	Income Tax Reconciliation Life Insurance Proceeds IncomeTaxReconciliationLifeInsuranceProceeds	3351000	USD
CY2017	colb	Effective Income Tax Rate Reconciliation Life Insurance Proceeds EffectiveIncomeTaxRateReconciliationLifeInsuranceProceeds	-0.02
CY2019	colb	Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationamount Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationamount	0	USD
CY2019	colb	Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationpercent Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationpercent	0
CY2018	colb	Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationamount Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationamount	0	USD
CY2018	colb	Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationpercent Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationpercent	0
CY2017	colb	Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationamount Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationamount	825000	USD
CY2017	colb	Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationpercent Effectiveincometaxratereconciliationnondeductibleexpensebusinesscombinationpercent	0.01
CY2019	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	0	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2018	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	0	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2017	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	12210000	USD
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0.07
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	5134000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.02
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	4931000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.02
CY2017	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	2550000	USD
CY2017	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.01
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	22000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.01
CY2018	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-2778000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.01
CY2017	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-856000	USD
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	47160000	USD
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.20
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	38954000	USD
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.18
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	65155000	USD
CY2017	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.37
CY2019Q4	us-gaap	Deferred Tax Liability Not Recognized Amount Of Unrecognized Deferred Tax Liability Undistributed Earnings Of Domestic Subsidiaries DeferredTaxLiabilityNotRecognizedAmountOfUnrecognizedDeferredTaxLiabilityUndistributedEarningsOfDomesticSubsidiaries	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	0	USD
CY2019Q4	colb	Federaloperatinglosscarryforwardssettobegintoexpirein2024 Federaloperatinglosscarryforwardssettobegintoexpirein2024	15800000	USD
CY2019Q4	colb	Idahostateoperatinglosscarryforwardssettobegintoexpirein2024 Idahostateoperatinglosscarryforwardssettobegintoexpirein2024	14300000	USD
CY2019Q4	colb	Oregonstateoperatinglosscarryforwardssettobegintoexpirein2024 Oregonstateoperatinglosscarryforwardssettobegintoexpirein2024	121000	USD
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2019	colb	Federalincometaxrate2018 Federalincometaxrate2018	0.21
CY2019	colb	Federalincometaxrate2018 Federalincometaxrate2018	0.21
CY2017	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	12200000	USD
CY2019Q4	colb	Capital Conservation Buffer CapitalConservationBuffer	0.0560
CY2019Q4	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	1317202000	USD
CY2019Q4	colb	Common Equity Tier1 Capitalto Risk Weighted Assets CommonEquityTier1CapitaltoRiskWeightedAssets	0.1245
CY2019Q4	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	476260000	USD
CY2019Q4	colb	Common Equity Tier1 Risk Based Capital Requiredfor Capital Adequacyto Risk Weighted Assets CommonEquityTier1RiskBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.0450
CY2019Q4	colb	Common Equity Tier One Capital Requiredfor Capital Adequacyminimumrequiredplusfullyphasedincapitalconservationbuffer CommonEquityTierOneCapitalRequiredforCapitalAdequacyminimumrequiredplusfullyphasedincapitalconservationbuffer	740849000	USD
CY2019Q4	colb	Common Equity Tier1 Risk Based Capital Requiredfor Capital Adequacyto Risk Weighted Assetspluscapitalconservationbufferfullyphasedin CommonEquityTier1RiskBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssetspluscapitalconservationbufferfullyphasedin	0.0700
CY2019Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	1317202000	USD
CY2019Q4	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.1245
CY2019Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	635014000	USD
CY2019Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2019Q4	colb	Tier One Risk Based Capital Requiredfor Capital Adequacypluscapitalconservationbufferfullyphasedin TierOneRiskBasedCapitalRequiredforCapitalAdequacypluscapitalconservationbufferfullyphasedin	899603000	USD
CY2019Q4	colb	Tier One Based Capital Requiredfor Capital Adequacyto Risk Weighted Assetspluscapitalconservationbufferfullyphasedin TierOneBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssetspluscapitalconservationbufferfullyphasedin	0.0850
CY2019Q4	us-gaap	Capital Capital	1439877000	USD
CY2019Q4	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1360
CY2019Q4	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	846685000	USD
CY2019Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2019Q4	colb	Capital Requiredfor Capital Adequacypluscapitalconservationbufferfullyphasedin CapitalRequiredforCapitalAdequacypluscapitalconservationbufferfullyphasedin	1111274000	USD
CY2019Q4	colb	Capital Requiredfor Capital Adequacyto Risk Weighted Assetspluscapitalconservationbufferfullyphasedin CapitalRequiredforCapitalAdequacytoRiskWeightedAssetspluscapitalconservationbufferfullyphasedin	0.1050
CY2019Q4	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	1317202000	USD
CY2019Q4	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.1017
CY2019Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	517938000	USD
CY2019Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2019Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	517938000	USD
CY2019Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2018Q4	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	1253394000	USD
CY2018Q4	colb	Common Equity Tier1 Capitalto Risk Weighted Assets CommonEquityTier1CapitaltoRiskWeightedAssets	0.1274
CY2018Q4	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	442717000	USD
CY2018Q4	colb	Common Equity Tier1 Risk Based Capital Requiredfor Capital Adequacyto Risk Weighted Assets CommonEquityTier1RiskBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.0450
CY2018Q4	colb	Common Equity Tier One Capital Requiredfor Capital Adequacypluscapitalconservationbufferphasein CommonEquityTierOneCapitalRequiredforCapitalAdequacypluscapitalconservationbufferphasein	627182000	USD
CY2018Q4	colb	Common Equity Tier1 Risk Based Capital Requiredfor Capital Adequacyto Risk Weighted Assetspluscapitalconservationbufferphasein CommonEquityTier1RiskBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssetspluscapitalconservationbufferphasein	0.0638
CY2018Q4	colb	Common Equity Tier One Capital Requiredfor Capital Adequacyminimumrequiredplusfullyphasedincapitalconservationbuffer CommonEquityTierOneCapitalRequiredforCapitalAdequacyminimumrequiredplusfullyphasedincapitalconservationbuffer	688670000	USD
CY2018Q4	colb	Common Equity Tier1 Risk Based Capital Requiredfor Capital Adequacyto Risk Weighted Assetspluscapitalconservationbufferfullyphasedin CommonEquityTier1RiskBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssetspluscapitalconservationbufferfullyphasedin	0.0700
CY2018Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	1253394000	USD
CY2018Q4	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.1274
CY2018Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	590289000	USD
CY2018Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2018Q4	colb	Tier One Risk Based Capital Requiredfor Capital Adequacypluscapitalconservationbufferphasein TierOneRiskBasedCapitalRequiredforCapitalAdequacypluscapitalconservationbufferphasein	774754000	USD
CY2018Q4	colb	Tier One Based Capital Requiredfor Capital Adequacyto Risk Weighted Assetspluscapitalconservationbufferphasein TierOneBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssetspluscapitalconservationbufferphasein	0.0788
CY2018Q4	colb	Tier One Risk Based Capital Requiredfor Capital Adequacypluscapitalconservationbufferfullyphasedin TierOneRiskBasedCapitalRequiredforCapitalAdequacypluscapitalconservationbufferfullyphasedin	836243000	USD
CY2018Q4	colb	Tier One Based Capital Requiredfor Capital Adequacyto Risk Weighted Assetspluscapitalconservationbufferfullyphasedin TierOneBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssetspluscapitalconservationbufferfullyphasedin	0.0850
CY2018Q4	us-gaap	Capital Capital	1376555000	USD
CY2018Q4	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1399
CY2018Q4	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	787052000	USD
CY2018Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2018Q4	colb	Capital Requiredfor Capital Adequacypluscapitalconservationbufferphasein CapitalRequiredforCapitalAdequacypluscapitalconservationbufferphasein	971517000	USD
CY2018Q4	colb	Capital Requiredfor Capital Adequacyto Risk Weighted Assetspluscapitalconservationbufferphasein CapitalRequiredforCapitalAdequacytoRiskWeightedAssetspluscapitalconservationbufferphasein	0.0988
CY2018Q4	colb	Capital Requiredfor Capital Adequacypluscapitalconservationbufferfullyphasedin CapitalRequiredforCapitalAdequacypluscapitalconservationbufferfullyphasedin	1033006000	USD
CY2018Q4	colb	Capital Requiredfor Capital Adequacyto Risk Weighted Assetspluscapitalconservationbufferfullyphasedin CapitalRequiredforCapitalAdequacytoRiskWeightedAssetspluscapitalconservationbufferfullyphasedin	0.1050
CY2018Q4	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	1253394000	USD
CY2018Q4	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.1024
CY2018Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	489399000	USD
CY2018Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2018Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	489399000	USD
CY2018Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2018Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	489399000	USD
CY2018Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2019Q4	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	133109000	USD
CY2019Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	132533000	USD
CY2019Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	135422000	USD
CY2019Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	128888000	USD
CY2019	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	529952000	USD
CY2019Q4	us-gaap	Interest Expense InterestExpense	8292000	USD
CY2019Q3	us-gaap	Interest Expense InterestExpense	10083000	USD
CY2019Q2	us-gaap	Interest Expense InterestExpense	10306000	USD
CY2019Q1	us-gaap	Interest Expense InterestExpense	7866000	USD
CY2019	us-gaap	Interest Expense InterestExpense	36547000	USD
CY2019Q4	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	124817000	USD
CY2019Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	122450000	USD
CY2019Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	125116000	USD
CY2019Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	121022000	USD
CY2019	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	493405000	USD
CY2019Q4	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	1614000	USD
CY2019Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	299000	USD
CY2019Q2	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	218000	USD
CY2019Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	1362000	USD
CY2019	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3493000	USD
CY2019Q4	us-gaap	Noninterest Income NoninterestIncome	21807000	USD
CY2019Q3	us-gaap	Noninterest Income NoninterestIncome	28030000	USD
CY2019Q2	us-gaap	Noninterest Income NoninterestIncome	25648000	USD
CY2019Q1	us-gaap	Noninterest Income NoninterestIncome	21696000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	97181000	USD
CY2019Q4	us-gaap	Noninterest Expense NoninterestExpense	86978000	USD
CY2019Q3	us-gaap	Noninterest Expense NoninterestExpense	87076000	USD
CY2019Q2	us-gaap	Noninterest Expense NoninterestExpense	86728000	USD
CY2019Q1	us-gaap	Noninterest Expense NoninterestExpense	84700000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	345482000	USD
CY2019Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	58032000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	63105000	USD
CY2019Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	63818000	USD
CY2019Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	56656000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	241611000	USD
CY2019Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11903000	USD
CY2019Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	12378000	USD
CY2019Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	12094000	USD
CY2019Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	10785000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	47160000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	46129000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	50727000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	51724000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	45871000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	194451000	USD
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.64
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.70
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.71
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.63
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.68
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.64
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.70
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.71
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.63
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.68
CY2018Q4	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	129801000	USD
CY2018Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	127575000	USD
CY2018Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	120549000	USD
CY2018Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	119144000	USD
CY2018	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	497069000	USD
CY2018Q4	us-gaap	Interest Expense InterestExpense	5913000	USD
CY2018Q3	us-gaap	Interest Expense InterestExpense	4779000	USD
CY2018Q2	us-gaap	Interest Expense InterestExpense	3875000	USD
CY2018Q1	us-gaap	Interest Expense InterestExpense	3663000	USD
CY2018	us-gaap	Interest Expense InterestExpense	18230000	USD
CY2018Q4	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	123888000	USD
CY2018Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	122796000	USD
CY2018Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	116674000	USD
CY2018Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	115481000	USD
CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	478839000	USD
CY2018Q4	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	1789000	USD
CY2018Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3153000	USD
CY2018Q2	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3975000	USD
CY2018Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	5852000	USD
CY2018	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	14769000	USD
CY2018Q4	us-gaap	Noninterest Income NoninterestIncome	20402000	USD
CY2018Q3	us-gaap	Noninterest Income NoninterestIncome	21019000	USD
CY2018Q2	us-gaap	Noninterest Income NoninterestIncome	23692000	USD
CY2018Q1	us-gaap	Noninterest Income NoninterestIncome	23143000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	88256000	USD
CY2018Q4	us-gaap	Noninterest Expense NoninterestExpense	87019000	USD
CY2018Q3	us-gaap	Noninterest Expense NoninterestExpense	82841000	USD
CY2018Q2	us-gaap	Noninterest Expense NoninterestExpense	84643000	USD
CY2018Q1	us-gaap	Noninterest Expense NoninterestExpense	85987000	USD
CY2018	us-gaap	Noninterest Expense NoninterestExpense	340490000	USD
CY2018Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	55482000	USD
CY2018Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	57821000	USD
CY2018Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	51748000	USD
CY2018Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	46785000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	211836000	USD
CY2018Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	10734000	USD
CY2018Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11406000	USD
CY2018Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	9999000	USD
CY2018Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	6815000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	38954000	USD
CY2018Q4	us-gaap	Net Income Loss NetIncomeLoss	44748000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	46415000	USD
CY2018Q2	us-gaap	Net Income Loss NetIncomeLoss	41749000	USD
CY2018Q1	us-gaap	Net Income Loss NetIncomeLoss	39970000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	172882000	USD
CY2018Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.61
CY2018Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.63
CY2018Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.57
CY2018Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.55
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.36
CY2018Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.61
CY2018Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.63
CY2018Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.57
CY2018Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.55
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.36
CY2019	colb	Depositaccountandtreasurymanagementfees Depositaccountandtreasurymanagementfees	35695000	USD
CY2018	colb	Depositaccountandtreasurymanagementfees Depositaccountandtreasurymanagementfees	36072000	USD
CY2019	colb	Cardrevenue Cardrevenue	15198000	USD
CY2018	colb	Cardrevenue Cardrevenue	19719000	USD
CY2019	colb	Financialservicesandtrustrevenue Financialservicesandtrustrevenue	12799000	USD
CY2018	colb	Financialservicesandtrustrevenue Financialservicesandtrustrevenue	12135000	USD
CY2019	colb	Revenuefromcontractswithcustomers Revenuefromcontractswithcustomers	63692000	USD
CY2018	colb	Revenuefromcontractswithcustomers Revenuefromcontractswithcustomers	67926000	USD
CY2019	colb	Noninterestincomeexcludingrevenuefromcontractswithcustomers Noninterestincomeexcludingrevenuefromcontractswithcustomers	33489000	USD
CY2018	colb	Noninterestincomeexcludingrevenuefromcontractswithcustomers Noninterestincomeexcludingrevenuefromcontractswithcustomers	20330000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	97181000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	88256000	USD

Files In Submission

Name	View Source	Status
0000887343-20-000070-index-headers.html	Edgar Link	pending
0000887343-20-000070-index.html	Edgar Link	pending
0000887343-20-000070.txt	Edgar Link	pending
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$COLB
COLUMBIA BANKING SYSTEM, INC. Stock $colb

2019 Q4 Form 10-K Financial Statement

#000088734320000070 Filed on February 27, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$COLB COLUMBIA BANKING SYSTEM, INC. Stock $colb

2019 Q4 Form 10-K Financial Statement

#000088734320000070 Filed on February 27, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$COLB
COLUMBIA BANKING SYSTEM, INC. Stock $colb