$COLB
Columbia Banking System Inc Stock $colb

$colb Overview Financials Valuation SEC Filings Company Website

2021 Q2 Form 10-Q Financial Statement

#000088734321000155 Filed on August 06, 2021

Income Statement

Concept	2021 Q2	2020 Q2	2020 Q1
Revenue	$127.4M	$126.2M	$130.9M
YoY Change	0.96%	-6.79%	1.56%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development	$7.402M	$7.981M	$7.099M
YoY Change	-7.25%	73.46%	52.05%
% of Gross Profit
Depreciation & Amortization	$5.700M	-$2.800M	$13.20M
YoY Change	-303.57%	-130.77%	60.98%
% of Gross Profit
Operating Expenses	$7.402M	$7.981M	$7.099M
YoY Change	-7.25%	73.46%	52.05%
Operating Profit
YoY Change
Interest Expense	$1.985M	$4.381M	$8.475M
YoY Change	-54.69%	-57.49%	7.74%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$69.58M	$44.78M	$17.86M
YoY Change	55.38%	-29.84%	-68.48%
Income Tax	$14.54M	$8.195M	$3.230M
% Of Pretax Income	20.89%	18.3%	18.09%
Net Earnings	$55.04M	$36.58M	$14.63M
YoY Change	50.45%	-29.27%	-68.11%
Net Earnings / Revenue	43.19%	28.98%	11.18%
Basic Earnings Per Share	$0.77	$0.52	$0.20
Diluted Earnings Per Share	$0.77	$0.52	$0.20
COMMON SHARES
Basic Shares Outstanding	70.99M shares	70.68M shares	71.21M shares
Diluted Shares Outstanding	71.16M shares	70.71M shares	71.26M shares

Balance Sheet

Concept	2021 Q2	2020 Q2	2020 Q1
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$831.5M	$1.098B	$215.8M
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	$158.8M	$164.4M	$164.6M
YoY Change	-3.37%	-1.75%	-2.09%
Goodwill	$765.8M	$765.8M	$765.8M
YoY Change	0.0%	0.0%	0.0%
Intangibles	$22.96M	$30.94M	$33.15M
YoY Change	-25.79%	-23.69%	-23.25%
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	$18.01B	$15.92B	$14.04B
YoY Change	13.14%	21.62%	7.46%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$71.00M	$51.00M	$34.00M
YoY Change	39.22%	2.0%	47.83%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$71.00M	$51.00M	$34.00M
YoY Change	39.22%	-5.56%	-37.04%
LONG-TERM LIABILITIES
Long-Term Debt	$35.00M	$35.00M	$35.00M
YoY Change	0.0%	0.0%	0.0%
Other Long-Term Liabilities	$221.0M	$269.0M	$230.0M
YoY Change	-17.84%	142.34%	121.15%
Total Long-Term Liabilities	$256.0M	$304.0M	$265.0M
YoY Change	-15.79%	108.22%	90.65%
TOTAL LIABILITIES
Total Short-Term Liabilities	$71.00M	$51.00M	$34.00M
Total Long-Term Liabilities	$256.0M	$304.0M	$265.0M
Total Liabilities	$15.68B	$13.64B	$11.82B
YoY Change	14.92%	24.52%	7.74%
SHAREHOLDERS EQUITY
Retained Earnings	$642.0M	$512.4M	$495.8M
YoY Change	25.3%	10.56%	12.03%
Common Stock	$1.665B	$1.654B	$1.651B
YoY Change	0.65%	0.56%	0.51%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$70.83M	$70.83M	$70.83M
YoY Change	0.0%	223.99%
Treasury Stock Shares	2.184M shares	2.184M shares	2.184M shares
Shareholders Equity	$2.333B	$2.277B	$2.214B
YoY Change
Total Liabilities & Shareholders Equity	$18.01B	$15.92B	$14.04B
YoY Change	13.14%	21.62%	7.46%

Cashflow Statement

Concept	2021 Q2	2020 Q2	2020 Q1
OPERATING ACTIVITIES
Net Income	$55.04M	$36.58M	$14.63M
YoY Change	50.45%	-29.27%	-68.11%
Depreciation, Depletion And Amortization	$5.700M	-$2.800M	$13.20M
YoY Change	-303.57%	-130.77%	60.98%
Cash From Operating Activities	$68.30M	$17.70M	$65.37M
YoY Change	285.88%	-61.52%	24.57%
INVESTING ACTIVITIES
Capital Expenditures	-$2.300M	-$2.800M	$1.650M
YoY Change	-17.86%	64.71%	-7.72%
Acquisitions
YoY Change
Other Investing Activities	-$709.2M	-$894.0M	$104.9M
YoY Change	-20.67%	-1211.94%	100.96%
Cash From Investing Activities	-$711.5M	-$896.8M	$103.2M
YoY Change	-20.66%	-1239.52%	104.74%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net			$20.00M
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	590.1M	1.761B	-$200.5M
YoY Change	-66.49%	-2354.8%	19.07%
NET CHANGE
Cash From Operating Activities	68.30M	17.70M	$65.37M
Cash From Investing Activities	-711.5M	-896.8M	$103.2M
Cash From Financing Activities	590.1M	1.761B	-$200.5M
Net Change In Cash	-53.10M	881.9M	-$31.92M
YoY Change	-106.02%	1792.49%	-51.28%
FREE CASH FLOW
Cash From Operating Activities	$68.30M	$17.70M	$65.37M
Capital Expenditures	-$2.300M	-$2.800M	$1.650M
Free Cash Flow	$70.60M	$20.50M	$63.72M
YoY Change	244.39%	-57.02%	25.71%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Entity Central Index Key EntityCentralIndexKey	0000887343
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q2
	dei	Amendment Flag AmendmentFlag	false
	dei	Document Type DocumentType	10-Q
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2021-06-30
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity File Number EntityFileNumber	000-20288
	dei	Entity Registrant Name EntityRegistrantName	COLUMBIA BANKING SYSTEM, INC.
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	WA
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	91-1422237
	dei	Entity Address Address Line1 EntityAddressAddressLine1	1301 A Street
	dei	Entity Address City Or Town EntityAddressCityOrTown	Tacoma
	dei	Entity Address State Or Province EntityAddressStateOrProvince	WA
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	98402-2156
	dei	City Area Code CityAreaCode	253
	dei	Local Phone Number LocalPhoneNumber	305-1900
	dei	Security12b Title Security12bTitle	Common Stock, No Par Value
	dei	Trading Symbol TradingSymbol	COLB
	dei	Security Exchange Name SecurityExchangeName	NASDAQ
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
	dei	Entity Small Business EntitySmallBusiness	false
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Shell Company EntityShellCompany	false
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	us-gaap	Noninterest Income Other NoninterestIncomeOther	1313000	USD
	us-gaap	Noninterest Income Other NoninterestIncomeOther	1676000	USD
CY2021Q2	us-gaap	Noninterest Income NoninterestIncome	22730000	USD
CY2020Q2	us-gaap	Noninterest Income NoninterestIncome	37259000	USD
	us-gaap	Noninterest Income NoninterestIncome	45896000	USD
	us-gaap	Noninterest Income NoninterestIncome	58466000	USD
CY2021Q2	us-gaap	Labor And Related Expense LaborAndRelatedExpense	53450000	USD
CY2020Q2	us-gaap	Labor And Related Expense LaborAndRelatedExpense	46043000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	105186000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	100885000	USD
CY2021Q2	us-gaap	Occupancy Net OccupancyNet	9038000	USD
CY2020Q2	us-gaap	Occupancy Net OccupancyNet	8812000	USD
	us-gaap	Occupancy Net OccupancyNet	18044000	USD
	us-gaap	Occupancy Net OccupancyNet	18009000	USD
CY2021Q2	us-gaap	Communications And Information Technology CommunicationsAndInformationTechnology	7402000	USD
CY2020Q2	us-gaap	Communications And Information Technology CommunicationsAndInformationTechnology	7981000	USD
	us-gaap	Communications And Information Technology CommunicationsAndInformationTechnology	15853000	USD
	us-gaap	Communications And Information Technology CommunicationsAndInformationTechnology	15080000	USD
CY2021Q2	us-gaap	Professional Fees ProfessionalFees	3264000	USD
CY2020Q2	us-gaap	Professional Fees ProfessionalFees	3483000	USD
	us-gaap	Professional Fees ProfessionalFees	6079000	USD
	us-gaap	Professional Fees ProfessionalFees	5585000	USD
CY2021Q2	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1852000	USD
CY2020Q2	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2210000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	3776000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	4520000	USD
CY2021Q2	colb	Taxes Licenses And Fees TaxesLicensesAndFees	1490000	USD
CY2020Q2	colb	Taxes Licenses And Fees TaxesLicensesAndFees	1244000	USD
	colb	Taxes Licenses And Fees TaxesLicensesAndFees	2749000	USD
	colb	Taxes Licenses And Fees TaxesLicensesAndFees	1868000	USD
CY2021Q2	us-gaap	Advertising Expense AdvertisingExpense	588000	USD
CY2020Q2	us-gaap	Advertising Expense AdvertisingExpense	837000	USD
	us-gaap	Advertising Expense AdvertisingExpense	1348000	USD
	us-gaap	Advertising Expense AdvertisingExpense	2142000	USD
CY2021Q2	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1112000	USD
CY2020Q2	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1034000	USD
	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	2217000	USD
	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1068000	USD
CY2021Q2	colb	Netcostbenefitofoperationofotherrealestateowned Netcostbenefitofoperationofotherrealestateowned	111000	USD
CY2020Q2	colb	Netcostbenefitofoperationofotherrealestateowned Netcostbenefitofoperationofotherrealestateowned	-200000	USD
	colb	Netcostbenefitofoperationofotherrealestateowned Netcostbenefitofoperationofotherrealestateowned	48000	USD
	colb	Netcostbenefitofoperationofotherrealestateowned Netcostbenefitofoperationofotherrealestateowned	-188000	USD
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	55039000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	36582000	USD
CY2021Q2	us-gaap	Other Noninterest Expense OtherNoninterestExpense	5809000	USD
CY2020Q2	us-gaap	Other Noninterest Expense OtherNoninterestExpense	9389000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	12375000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	16135000	USD
CY2021Q2	us-gaap	Noninterest Expense NoninterestExpense	84116000	USD
CY2020Q2	us-gaap	Noninterest Expense NoninterestExpense	80833000	USD
	us-gaap	Noninterest Expense NoninterestExpense	167675000	USD
	us-gaap	Noninterest Expense NoninterestExpense	165104000	USD
CY2021Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	69576000	USD
CY2020Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	44777000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	133977000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	62635000	USD
CY2021Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	14537000	USD
CY2020Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	8195000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	27085000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11425000	USD
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.50
	us-gaap	Net Income Loss NetIncomeLoss	106892000	USD
	us-gaap	Net Income Loss NetIncomeLoss	51210000	USD
CY2021Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.77
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.52
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.72
CY2021Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.77
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.52
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.50
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.72
CY2021Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70987000	shares
CY2020Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70679000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70924000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70942000	shares
CY2021Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	71164000	shares
CY2020Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	70711000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	71079000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	70981000	shares
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	55039000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	36582000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-6619000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-12984000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	21850000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	42860000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	73000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	0	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	241000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	0	USD
CY2021Q2	us-gaap	Oci Debt Securities Available For Sale Transfer To Held To Maturity Adjustment From Aoci For Amortization Of Gain Loss Tax OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossTax	105000	USD
CY2020Q2	us-gaap	Oci Debt Securities Available For Sale Transfer To Held To Maturity Adjustment From Aoci For Amortization Of Gain Loss Tax OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossTax	0	USD
CY2021Q2	us-gaap	Oci Debt Securities Available For Sale Transfer To Held To Maturity Adjustment From Aoci For Amortization Of Gain Loss After Tax OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossAfterTax	345000	USD
CY2020Q2	us-gaap	Oci Debt Securities Available For Sale Transfer To Held To Maturity Adjustment From Aoci For Amortization Of Gain Loss After Tax OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossAfterTax	0	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	21264000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	42860000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	-34000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	-24000	USD
CY2021Q2	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	115000	USD
CY2020Q2	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	79000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-115000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-79000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax	0	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax	-791000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	0	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	2611000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax	604000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax	510000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax	1998000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax	1680000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	-1998000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	931000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	19381000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	43870000	USD
CY2021Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	74420000	USD
CY2020Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	80452000	USD
	us-gaap	Net Income Loss NetIncomeLoss	106892000	USD
	us-gaap	Net Income Loss NetIncomeLoss	51210000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	24463000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-37126000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-80755000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	122556000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	73000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	58000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	241000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	191000	USD
	us-gaap	Oci Debt Securities Available For Sale Transfer To Held To Maturity Adjustment From Aoci For Amortization Of Gain Loss Tax OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossTax	105000	USD
	us-gaap	Oci Debt Securities Available For Sale Transfer To Held To Maturity Adjustment From Aoci For Amortization Of Gain Loss Tax OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossTax	0	USD
	us-gaap	Oci Debt Securities Available For Sale Transfer To Held To Maturity Adjustment From Aoci For Amortization Of Gain Loss After Tax OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossAfterTax	345000	USD
	us-gaap	Oci Debt Securities Available For Sale Transfer To Held To Maturity Adjustment From Aoci For Amortization Of Gain Loss After Tax OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossAfterTax	0	USD
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-81341000	USD
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	122365000	USD
	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	-69000	USD
	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	-48000	USD
	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	230000	USD
	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	159000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-230000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-159000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax	0	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax	-6237000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	0	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	20588000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax	1203000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax	728000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax	3975000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax	2402000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	-3975000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	18186000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-85086000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	140710000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	21806000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	191920000	USD
CY2021Q1	us-gaap	Stockholders Equity StockholdersEquity	2275063000	USD
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	55039000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	19381000	USD
CY2021Q2	colb	Stock Adjustment Value Deferred Compensation StockAdjustmentValueDeferredCompensation	-8000	USD
CY2021Q2	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	3908000	USD
CY2021Q2	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	76000	USD
CY2021Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.28
CY2021Q2	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	20061000	USD
CY2021Q2	us-gaap	Stockholders Equity StockholdersEquity	2333246000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	2347607000	USD
	us-gaap	Net Income Loss NetIncomeLoss	106892000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-85086000	USD
	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	1098000	USD
	colb	Stock Adjustment Value Deferred Compensation StockAdjustmentValueDeferredCompensation	-8000	USD
	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	6936000	USD
	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	4071000	USD
	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.56
	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	40122000	USD
CY2021Q2	us-gaap	Stockholders Equity StockholdersEquity	2333246000	USD
CY2020Q1	us-gaap	Stockholders Equity StockholdersEquity	2213602000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	36582000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	43870000	USD
CY2020Q2	colb	Stock Adjustment Deferred Compensation Shares StockAdjustmentDeferredCompensationShares	0	shares
CY2020Q2	colb	Stock Adjustment Value Deferred Compensation StockAdjustmentValueDeferredCompensation	1000	USD
CY2020Q2	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	2737000	USD
CY2020Q2	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	8000	USD
CY2020Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.28
CY2020Q2	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	20029000	USD
CY2020Q2	us-gaap	Stockholders Equity StockholdersEquity	2276755000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	2159962000	USD
	us-gaap	Net Income Loss NetIncomeLoss	51210000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	140710000	USD
	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	945000	USD
	colb	Stock Adjustment Deferred Compensation Shares StockAdjustmentDeferredCompensationShares	0	shares
	colb	Stock Adjustment Value Deferred Compensation StockAdjustmentValueDeferredCompensation	4000	USD
	colb	Stock Adjustment Value Deferred Compensation StockAdjustmentValueDeferredCompensation	4000	USD
	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	4909000	USD
	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	2482000	USD
	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.78
	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	56046000	USD
	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	20000000	USD
CY2020Q2	us-gaap	Stockholders Equity StockholdersEquity	2276755000	USD
	us-gaap	Net Income Loss NetIncomeLoss	106892000	USD
	us-gaap	Net Income Loss NetIncomeLoss	51210000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	-6300000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	75000000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	6936000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	4909000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	7056000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	10382000	USD
	us-gaap	Available For Sale Securities Gross Realized Gain Loss Net AvailableForSaleSecuritiesGrossRealizedGainLossNet	314000	USD
	us-gaap	Available For Sale Securities Gross Realized Gain Loss Net AvailableForSaleSecuritiesGrossRealizedGainLossNet	16674000	USD
	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	279000	USD
	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	705000	USD
	colb	Netgainlossonsaleandvaluationadjustmentsof Oreo NetgainlossonsaleandvaluationadjustmentsofOREO	-40000	USD
	colb	Netgainlossonsaleandvaluationadjustmentsof Oreo NetgainlossonsaleandvaluationadjustmentsofOREO	-18000	USD
	colb	Gainonbankownedlifeinsurancedeathbenefit Gainonbankownedlifeinsurancedeathbenefit	209000	USD
	colb	Gainonbankownedlifeinsurancedeathbenefit Gainonbankownedlifeinsurancedeathbenefit	0	USD
	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	195632000	USD
	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	217017000	USD
	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	208789000	USD
	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	205932000	USD
	us-gaap	Increase Decrease In Mortgage Loans Held For Sale IncreaseDecreaseInMortgageLoansHeldForSale	-145000	USD
	us-gaap	Increase Decrease In Mortgage Loans Held For Sale IncreaseDecreaseInMortgageLoansHeldForSale	0	USD
	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	-2484000	USD
	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	12310000	USD
	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-49000	USD
	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-219000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-12583000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	93919000	USD
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-14700000	USD
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	76500000	USD
CY2020Q2	colb	Visa Class Bsharessharessold VisaClassBsharessharessold	17360	shares
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	127442000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	83107000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	177399000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	1026250000	USD
	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	1527512000	USD
	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	259236000	USD
	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	22915000	USD
	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	0	USD
	us-gaap	Payments To Acquire Loans Receivable PaymentsToAcquireLoansReceivable	74383000	USD
	us-gaap	Payments To Acquire Loans Receivable PaymentsToAcquireLoansReceivable	0	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	3087000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	4490000	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	0	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	53240000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	26914000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	194105000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Equity ProceedsFromSaleOfAvailableForSaleSecuritiesEquity	0	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Equity ProceedsFromSaleOfAvailableForSaleSecuritiesEquity	3000000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	385408000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	265072000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	8711000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	0	USD
	us-gaap	Proceeds From Sales Of Assets Investing Activities ProceedsFromSalesOfAssetsInvestingActivities	4296000	USD
	us-gaap	Proceeds From Sales Of Assets Investing Activities ProceedsFromSalesOfAssetsInvestingActivities	932000	USD
	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	0	USD
	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	85080000	USD
	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	132000	USD
	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	353000	USD
	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	671000	USD
	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	1050000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1379164000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-793624000	USD
	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	1475570000	USD
	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	2446782000	USD
	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	-2865000	USD
	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	-12958000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Advances ProceedsFromFederalHomeLoanBankAdvances	10000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Advances ProceedsFromFederalHomeLoanBankAdvances	1331000000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	0	USD
	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	222010000	USD
	us-gaap	Proceeds From Other Debt ProceedsFromOtherDebt	0	USD
	us-gaap	Proceeds From Other Debt ProceedsFromOtherDebt	9222000	USD
	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1098000	USD
	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	945000	USD
	us-gaap	Payments For Federal Home Loan Bank Advances PaymentsForFederalHomeLoanBankAdvances	10000	USD
	us-gaap	Payments For Federal Home Loan Bank Advances PaymentsForFederalHomeLoanBankAdvances	2127000000	USD
	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	0	USD
	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	222010000	USD
	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	0	USD
	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	9222000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	40244000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	55750000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	20000000	USD
	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	4071000	USD
	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	2482000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	1429488000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	1560537000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	177766000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	850020000	USD
CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	653766000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	247673000	USD
CY2021Q2	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	831532000	USD
CY2020Q2	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	1097693000	USD
	us-gaap	Interest Paid Net InterestPaidNet	4082000	USD
	us-gaap	Interest Paid Net InterestPaidNet	13075000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	28474000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	21501000	USD
	colb	Securities Transfer From Afs To Htm Fair Value SecuritiesTransferFromAFSToHTMFairValue	2012123000	USD
	colb	Securities Transfer From Afs To Htm Fair Value SecuritiesTransferFromAFSToHTMFairValue	0	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	0	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	558000	USD
	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	0	USD
	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	9000	USD
	colb	Changeindividendspayableonunvestedshares Changeindividendspayableonunvestedshares	-122000	USD
	colb	Changeindividendspayableonunvestedshares Changeindividendspayableonunvestedshares	296000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	4103196000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	103979000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	17109000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	4190066000	USD
CY2021Q2	us-gaap	Debt Securities Held To Maturity Amortized Cost After Allowance For Credit Loss DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss	2024715000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	9586000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	1321000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	2032980000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	4997529000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	219873000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	7268000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	5210134000	USD
CY2021Q2	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	0	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	0	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2021Q2	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	26914000	USD
CY2020Q2	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	26914000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	194105000	USD
CY2021Q2	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	751000	USD
CY2020Q2	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	0	USD
	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	751000	USD
	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	435000	USD
CY2021Q2	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	437000	USD
CY2020Q2	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	0	USD
	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	437000	USD
	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	186000	USD
CY2021Q2	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	0	USD
CY2020Q2	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	16425000	USD
	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	0	USD
	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	16425000	USD
CY2021Q2	us-gaap	Gain Loss On Investments GainLossOnInvestments	314000	USD
CY2020Q2	us-gaap	Gain Loss On Investments GainLossOnInvestments	16425000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	314000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	16674000	USD
CY2021Q2	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	0	USD
CY2020Q2	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	16425000	USD
	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	0	USD
	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	16425000	USD
CY2021Q2	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	0	USD
CY2020Q2	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	3000000	USD
	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	0	USD
	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	3000000	USD
CY2021Q2	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	0	USD
CY2020Q2	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	13425000	USD
	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	0	USD
	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	13425000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	57266000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	57900000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount	0	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities Next Rolling Twelve Months Fair Value HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	0	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	751065000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	779527000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount	26224000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	26163000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	1531719000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	1578489000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount	1241524000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	1248569000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	1763146000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	1774150000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount	756967000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue	758248000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	4103196000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	4190066000	USD
CY2021Q2	us-gaap	Debt Securities Held To Maturity Amortized Cost After Allowance For Credit Loss DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss	2024715000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	2032980000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Restricted DebtSecuritiesAvailableForSaleRestricted	780201000	USD
CY2021Q2	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	1413001000	USD
CY2021Q2	colb	Availableforsale Securities Continuous Unrealized Loss Position Lessthan12 Months Aggregate Loss Instant AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAggregateLossInstant	16707000	USD
CY2021Q2	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	25010000	USD
CY2021Q2	colb	Availableforsale Securities Continuous Unrealized Loss Position12 Monthsor Longer Aggregate Lossinstant AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAggregateLossinstant	402000	USD
CY2021Q2	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	1438011000	USD
CY2021Q2	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	17109000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	880507000	USD
CY2020Q4	colb	Availableforsale Securities Continuous Unrealized Loss Position Lessthan12 Months Aggregate Loss Instant AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAggregateLossInstant	6453000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	18597000	USD
CY2020Q4	colb	Availableforsale Securities Continuous Unrealized Loss Position12 Monthsor Longer Aggregate Lossinstant AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAggregateLossinstant	815000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	899104000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	7268000	USD
CY2021Q2	colb	Visa Class Bsharesremainingshares VisaClassBsharesremainingshares	77683	shares
CY2021Q2	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	13400000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	9693116000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	9427660000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	142988000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	149140000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	9550128000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	9278520000	USD
CY2021Q2	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	24021000	USD
CY2021Q2	us-gaap	Notes Receivable Gross NotesReceivableGross	9693116000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	34806000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	9427660000	USD
CY2021Q2	colb	Financing Receivable Accrued Interest Reversed Through Interest Income FinancingReceivableAccruedInterestReversedThroughInterestIncome	214000	USD
CY2020Q2	colb	Financing Receivable Accrued Interest Reversed Through Interest Income FinancingReceivableAccruedInterestReversedThroughInterestIncome	673000	USD
	colb	Financing Receivable Accrued Interest Reversed Through Interest Income FinancingReceivableAccruedInterestReversedThroughInterestIncome	433000	USD
	colb	Financing Receivable Accrued Interest Reversed Through Interest Income FinancingReceivableAccruedInterestReversedThroughInterestIncome	1461000	USD
CY2021Q2	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	13811000	USD
CY2020Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	20911000	USD
CY2021Q2	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	4	Modifications
CY2021Q2	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	1757000	USD
CY2021Q2	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	1757000	USD
CY2020Q2	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	5	Modifications
CY2020Q2	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	1818000	USD
CY2020Q2	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	1818000	USD
	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	14	Modifications
	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	3368000	USD
	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	3368000	USD
	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	9	Modifications
	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	3053000	USD
	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	3053000	USD
CY2021Q2	colb	Financing Receivable Modifications Additional Commitment To Lend FinancingReceivableModificationsAdditionalCommitmentToLend	988000	USD
CY2020Q4	colb	Financing Receivable Modifications Additional Commitment To Lend FinancingReceivableModificationsAdditionalCommitmentToLend	651000	USD
	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	contract
CY2021Q2	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	contract
CY2020Q2	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	contract
	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	contract
	colb	Loan Modifications Short Term Deferments Not Classified As Tdr Number Of Contracts LoanModificationsShortTermDefermentsNotClassifiedAsTDRNumberOfContracts	10	contract
	colb	Loan Modifications Short Term Deferments Not Classified As Tdr Net Of Unearned Income LoanModificationsShortTermDefermentsNotClassifiedAsTDRNetOfUnearnedIncome	40700000	USD
CY2021Q2	colb	Paycheck Protection Program Pp Ploansnetofunearnedincome PaycheckProtectionProgramPPPloansnetofunearnedincome	691900000	USD
CY2021Q2	colb	Minimumloanbalanceofnonaccrualcollateraldependentloansconsideredfor Acl MinimumloanbalanceofnonaccrualcollateraldependentloansconsideredforACL	500000	USD
CY2021Q1	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	148294000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	1940000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	2134000	USD
CY2021Q2	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	-5500000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	142988000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	149140000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	5406000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	5554000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	-6300000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	142988000	USD
CY2020Q1	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	122074000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	5640000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	1612000	USD
CY2020Q2	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	33500000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	151546000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	83968000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	12429000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	3375000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	75000000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	151546000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses Period Increase Decrease FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease	-6200000	USD
CY2021Q1	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	9800000	USD
CY2020Q1	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	6000000	USD
CY2020Q4	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	8300000	USD
CY2019Q4	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	3430000	USD
CY2021Q2	colb	Allowance For Loan And Lease Losses Net Changes In Unfunded Commitments And Letters Of Credit Allowance AllowanceForLoanAndLeaseLossesNetChangesInUnfundedCommitmentsAndLettersOfCreditAllowance	200000	USD
CY2020Q2	colb	Allowance For Loan And Lease Losses Net Changes In Unfunded Commitments And Letters Of Credit Allowance AllowanceForLoanAndLeaseLossesNetChangesInUnfundedCommitmentsAndLettersOfCreditAllowance	2800000	USD
	colb	Allowance For Loan And Lease Losses Net Changes In Unfunded Commitments And Letters Of Credit Allowance AllowanceForLoanAndLeaseLossesNetChangesInUnfundedCommitmentsAndLettersOfCreditAllowance	1700000	USD
	colb	Allowance For Loan And Lease Losses Net Changes In Unfunded Commitments And Letters Of Credit Allowance AllowanceForLoanAndLeaseLossesNetChangesInUnfundedCommitmentsAndLettersOfCreditAllowance	3800000	USD
CY2021Q2	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	10000000	USD
CY2020Q2	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	8800000	USD
CY2021Q2	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	10000000	USD
CY2020Q2	colb	Allowance For Unfunded Loan Commitments And Letters Of Credit AllowanceForUnfundedLoanCommitmentsAndLettersOfCredit	8800000	USD
CY2021Q2	us-gaap	Financing Receivable Originated In Current Fiscal Year FinancingReceivableOriginatedInCurrentFiscalYear	1621922000	USD
CY2021Q2	us-gaap	Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear	1615362000	USD
CY2021Q2	us-gaap	Financing Receivable Originated Two Years Before Latest Fiscal Year FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear	1239041000	USD
CY2021Q2	us-gaap	Financing Receivable Originated Three Years Before Latest Fiscal Year FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear	854436000	USD
CY2021Q2	us-gaap	Financing Receivable Originated Four Years Before Latest Fiscal Year FinancingReceivableOriginatedFourYearsBeforeLatestFiscalYear	785447000	USD
CY2021Q2	us-gaap	Financing Receivable Originated Five Or More Years Before Latest Fiscal Year FinancingReceivableOriginatedFiveOrMoreYearsBeforeLatestFiscalYear	1855933000	USD
CY2021Q2	us-gaap	Financing Receivable Revolving FinancingReceivableRevolving	1693637000	USD
CY2021Q2	colb	Financing Receivable Revolving Convertedto Term Loans FinancingReceivableRevolvingConvertedtoTermLoans	27338000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	9693116000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	142988000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	9550128000	USD
CY2020Q4	us-gaap	Financing Receivable Originated In Current Fiscal Year FinancingReceivableOriginatedInCurrentFiscalYear	2223383000	USD
CY2020Q4	us-gaap	Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear	1379336000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Two Years Before Latest Fiscal Year FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear	985423000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Three Years Before Latest Fiscal Year FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear	875545000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Four Years Before Latest Fiscal Year FinancingReceivableOriginatedFourYearsBeforeLatestFiscalYear	812034000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Five Or More Years Before Latest Fiscal Year FinancingReceivableOriginatedFiveOrMoreYearsBeforeLatestFiscalYear	1413553000	USD
CY2020Q4	us-gaap	Financing Receivable Revolving FinancingReceivableRevolving	1687345000	USD
CY2020Q4	colb	Financing Receivable Revolving Convertedto Term Loans FinancingReceivableRevolvingConvertedtoTermLoans	51041000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	9427660000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	149140000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	9278520000	USD
CY2021Q1	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	521000	USD
CY2020Q1	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	510000	USD
CY2020Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	553000	USD
CY2019Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	552000	USD
CY2021Q2	colb	Real Estate Acquired Through Foreclosure Transfers In Net Of Write Downs RealEstateAcquiredThroughForeclosureTransfersInNetOfWriteDowns	0	USD
CY2020Q2	colb	Real Estate Acquired Through Foreclosure Transfers In Net Of Write Downs RealEstateAcquiredThroughForeclosureTransfersInNetOfWriteDowns	558000	USD
	colb	Real Estate Acquired Through Foreclosure Transfers In Net Of Write Downs RealEstateAcquiredThroughForeclosureTransfersInNetOfWriteDowns	0	USD
	colb	Real Estate Acquired Through Foreclosure Transfers In Net Of Write Downs RealEstateAcquiredThroughForeclosureTransfersInNetOfWriteDowns	558000	USD
CY2021Q2	colb	Transfer Other Real Estate Write Down TransferOtherRealEstateWriteDown	140000	USD
CY2020Q2	colb	Transfer Other Real Estate Write Down TransferOtherRealEstateWriteDown	0	USD
	colb	Transfer Other Real Estate Write Down TransferOtherRealEstateWriteDown	140000	USD
	colb	Transfer Other Real Estate Write Down TransferOtherRealEstateWriteDown	0	USD
CY2021Q2	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	0	USD
CY2020Q2	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	303000	USD
	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	132000	USD
	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	345000	USD
CY2021Q2	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	0	USD
CY2020Q2	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-18000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	100000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-18000	USD
CY2021Q2	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	381000	USD
CY2020Q2	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	747000	USD
CY2021Q2	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	381000	USD
CY2020Q2	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	747000	USD
CY2021Q2	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	166000	USD
CY2021Q2	us-gaap	Goodwill Goodwill	765842000	USD
CY2020Q2	us-gaap	Goodwill Goodwill	765842000	USD
CY2021Q2	us-gaap	Goodwill Goodwill	765842000	USD
CY2020Q2	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	919000	USD
CY2021Q2	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	919000	USD
CY2020Q2	us-gaap	Goodwill Goodwill	765842000	USD
CY2021Q2	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	919000	USD
CY2020Q2	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	919000	USD
CY2021Q2	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	22958000	USD
CY2020Q2	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	30938000	USD
CY2021Q2	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	22958000	USD
CY2020Q2	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	30938000	USD
CY2021Q2	colb	Goodwill And Intangible Assets Total GoodwillAndIntangibleAssetsTotal	788800000	USD
CY2020Q2	colb	Goodwill And Intangible Assets Total GoodwillAndIntangibleAssetsTotal	796780000	USD
CY2021Q2	colb	Goodwill And Intangible Assets Total GoodwillAndIntangibleAssetsTotal	788800000	USD
CY2020Q2	colb	Goodwill And Intangible Assets Total GoodwillAndIntangibleAssetsTotal	796780000	USD
CY2021Q2	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	3488000	USD
CY2021Q2	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	3432000	USD
CY2021Q2	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	5880000	USD
CY2021Q2	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	4552000	USD
CY2021Q2	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	2415000	USD
CY2021Q2	us-gaap	Line Of Credit Facility Maximum Borrowing Capacity LineOfCreditFacilityMaximumBorrowingCapacity	15000000.0	USD
CY2021Q2	us-gaap	Interest Rate Cash Flow Hedge Gain Loss To Be Reclassified During Next12 Months Net InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet	10400000	USD
CY2021Q2	us-gaap	Unrealized Gain Loss On Interest Rate Cash Flow Hedges Pretax Accumulated Other Comprehensive Income Loss UnrealizedGainLossOnInterestRateCashFlowHedgesPretaxAccumulatedOtherComprehensiveIncomeLoss	0	USD
CY2020Q2	us-gaap	Unrealized Gain Loss On Interest Rate Cash Flow Hedges Pretax Accumulated Other Comprehensive Income Loss UnrealizedGainLossOnInterestRateCashFlowHedgesPretaxAccumulatedOtherComprehensiveIncomeLoss	3402000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	2602000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	2190000	USD
	us-gaap	Unrealized Gain Loss On Interest Rate Cash Flow Hedges Pretax Accumulated Other Comprehensive Income Loss UnrealizedGainLossOnInterestRateCashFlowHedgesPretaxAccumulatedOtherComprehensiveIncomeLoss	0	USD
	us-gaap	Unrealized Gain Loss On Interest Rate Cash Flow Hedges Pretax Accumulated Other Comprehensive Income Loss UnrealizedGainLossOnInterestRateCashFlowHedgesPretaxAccumulatedOtherComprehensiveIncomeLoss	26825000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	5178000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	3130000	USD
	colb	Gain On Termination Of Interest Rate Collar GainOnTerminationOfInterestRateCollar	34400000	USD
CY2021Q2	colb	Repurchaseagreementsamountsoffsetinbalancesheet Repurchaseagreementsamountsoffsetinbalancesheet	0	USD
CY2021Q2	colb	Repurchaseagreementsnetamountpresentedinstatementoffinancialposition Repurchaseagreementsnetamountpresentedinstatementoffinancialposition	70994000	USD
CY2021Q2	us-gaap	Securities Sold Under Agreements To Repurchase Collateral Right To Reclaim Securities SecuritiesSoldUnderAgreementsToRepurchaseCollateralRightToReclaimSecurities	70994000	USD
CY2021Q2	colb	Securitiessoldunderagreementstorepurchaseamountnotoffset Securitiessoldunderagreementstorepurchaseamountnotoffset	0	USD
CY2020Q4	colb	Repurchaseagreementsamountsoffsetinbalancesheet Repurchaseagreementsamountsoffsetinbalancesheet	0	USD
CY2020Q4	colb	Repurchaseagreementsnetamountpresentedinstatementoffinancialposition Repurchaseagreementsnetamountpresentedinstatementoffinancialposition	73859000	USD
CY2021Q1	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	77728000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	21850000	USD
CY2020Q4	us-gaap	Securities Sold Under Agreements To Repurchase Collateral Right To Reclaim Securities SecuritiesSoldUnderAgreementsToRepurchaseCollateralRightToReclaimSecurities	73859000	USD
CY2020Q4	colb	Securitiessoldunderagreementstorepurchaseamountnotoffset Securitiessoldunderagreementstorepurchaseamountnotoffset	0	USD
CY2021Q2	us-gaap	Secured Borrowings Gross Including Not Subject To Master Netting Arrangement SecuredBorrowingsGrossIncludingNotSubjectToMasterNettingArrangement	70994000	USD
CY2021Q2	us-gaap	Secured Borrowings Gross Difference Amount SecuredBorrowingsGrossDifferenceAmount	0	USD
CY2021Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.28
CY2021Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.28
CY2021Q2	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	2469000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	19381000	USD
CY2021Q2	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	97109000	USD
CY2020Q1	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	137207000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	45471000	USD
CY2020Q2	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	1601000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	43870000	USD
CY2020Q2	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	181077000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	182195000	USD
	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	-80755000	USD
	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	4331000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-85086000	USD
CY2021Q2	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	97109000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	40367000	USD
	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	143144000	USD
	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	2434000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	140710000	USD
CY2020Q2	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	181077000	USD
CY2021Q2	colb	Visa Class Bsharesremainingshares VisaClassBsharesremainingshares	77683	shares
CY2021Q1	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	13425000	USD
CY2020Q1	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	0	USD
CY2020Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	13425000	USD
CY2019Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	0	USD
CY2020Q2	us-gaap	Fair Value Option Changes In Fair Value Gain Loss1 FairValueOptionChangesInFairValueGainLoss1	0	USD
CY2021Q2	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	0	USD
CY2020Q2	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	13425000	USD
	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	0	USD
	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	13425000	USD
CY2021Q2	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	13425000	USD
CY2020Q2	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	13425000	USD
CY2021Q2	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	13425000	USD
CY2020Q2	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	13425000	USD
CY2021Q2	colb	Fair Value Loans Held For Sale Mandatory Delivery Method Fv Option FairValueLoansHeldForSaleMandatoryDeliveryMethodFVOption	14413000	USD
CY2021Q2	colb	Fair Value Fv Option Aggregate Unpaid Balance Loans And Long Term Receivables FairValueFVOptionAggregateUnpaidBalanceLoansAndLongTermReceivables	14050000	USD
CY2021Q2	us-gaap	Fair Value Option Aggregate Differences Loans And Long Term Receivables FairValueOptionAggregateDifferencesLoansAndLongTermReceivables	363000	USD
CY2020Q2	colb	Fair Value Loans Held For Sale Mandatory Delivery Method Fv Option FairValueLoansHeldForSaleMandatoryDeliveryMethodFVOption	14760000	USD
CY2021Q2	us-gaap	Fair Value Option Changes In Fair Value Gain Loss1 FairValueOptionChangesInFairValueGainLoss1	-57000	USD
CY2020Q2	colb	Fair Value Fv Option Aggregate Unpaid Balance Loans And Long Term Receivables FairValueFVOptionAggregateUnpaidBalanceLoansAndLongTermReceivables	14252000	USD
CY2020Q2	us-gaap	Fair Value Option Aggregate Differences Loans And Long Term Receivables FairValueOptionAggregateDifferencesLoansAndLongTermReceivables	508000	USD
	us-gaap	Fair Value Option Changes In Fair Value Gain Loss1 FairValueOptionChangesInFairValueGainLoss1	-145000	USD
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	55039000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	36582000	USD
	us-gaap	Net Income Loss NetIncomeLoss	106892000	USD
	us-gaap	Net Income Loss NetIncomeLoss	51210000	USD
CY2021Q2	colb	Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares	70000	USD
CY2020Q2	colb	Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares	139000	USD
	colb	Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares	227000	USD
	colb	Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares Earningsallocatedtoparticipatingsecuritiesnonvestedrestrictedshares	325000	USD
CY2021Q2	colb	Basic Earnings Allocated To Common Shareholders BasicEarningsAllocatedToCommonShareholders	54969000	USD
CY2020Q2	colb	Basic Earnings Allocated To Common Shareholders BasicEarningsAllocatedToCommonShareholders	36443000	USD
	colb	Basic Earnings Allocated To Common Shareholders BasicEarningsAllocatedToCommonShareholders	106665000	USD
	colb	Basic Earnings Allocated To Common Shareholders BasicEarningsAllocatedToCommonShareholders	50885000	USD
CY2021Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70987000	shares
CY2020Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70679000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70924000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70942000	shares
CY2021Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.77
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.52
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.50
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.72
CY2021Q2	colb	Diluted Earnings Allocated To Common Shareholders DilutedEarningsAllocatedToCommonShareholders	54969000	USD
CY2020Q2	colb	Diluted Earnings Allocated To Common Shareholders DilutedEarningsAllocatedToCommonShareholders	36443000	USD
	colb	Diluted Earnings Allocated To Common Shareholders DilutedEarningsAllocatedToCommonShareholders	106665000	USD
	colb	Diluted Earnings Allocated To Common Shareholders DilutedEarningsAllocatedToCommonShareholders	50885000	USD
CY2021Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70987000	shares
CY2020Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70679000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70924000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70942000	shares
CY2021Q2	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	177000	shares
CY2020Q2	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	32000	shares
	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	155000	shares
	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	39000	shares
CY2021Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	71164000	shares
CY2020Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	70711000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	71079000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	70981000	shares
CY2021Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.77
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.52
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.50
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.72
CY2021Q2	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	248000	shares
CY2020Q2	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	571000	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	158000	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	450000	shares
CY2021Q2	colb	Depositaccountandtreasurymanagementfees Depositaccountandtreasurymanagementfees	6701000	USD
CY2020Q2	colb	Depositaccountandtreasurymanagementfees Depositaccountandtreasurymanagementfees	6092000	USD
	colb	Depositaccountandtreasurymanagementfees Depositaccountandtreasurymanagementfees	13059000	USD
	colb	Depositaccountandtreasurymanagementfees Depositaccountandtreasurymanagementfees	13880000	USD
CY2021Q2	colb	Cardrevenue Cardrevenue	4773000	USD
CY2020Q2	colb	Cardrevenue Cardrevenue	3079000	USD
	colb	Cardrevenue Cardrevenue	8506000	USD
	colb	Cardrevenue Cardrevenue	6597000	USD
CY2021Q2	colb	Financialservicesandtrustrevenue Financialservicesandtrustrevenue	4245000	USD
CY2020Q2	colb	Financialservicesandtrustrevenue Financialservicesandtrustrevenue	3163000	USD
	colb	Financialservicesandtrustrevenue Financialservicesandtrustrevenue	7626000	USD
	colb	Financialservicesandtrustrevenue Financialservicesandtrustrevenue	6228000	USD
CY2021Q2	colb	Revenuefromcontractswithcustomers Revenuefromcontractswithcustomers	15719000	USD
CY2020Q2	colb	Revenuefromcontractswithcustomers Revenuefromcontractswithcustomers	12334000	USD
	colb	Revenuefromcontractswithcustomers Revenuefromcontractswithcustomers	29191000	USD
	colb	Revenuefromcontractswithcustomers Revenuefromcontractswithcustomers	26705000	USD
CY2021Q2	colb	Noninterestincomeexcludingrevenuefromcontractswithcustomers Noninterestincomeexcludingrevenuefromcontractswithcustomers	7011000	USD
CY2020Q2	colb	Noninterestincomeexcludingrevenuefromcontractswithcustomers Noninterestincomeexcludingrevenuefromcontractswithcustomers	24925000	USD
	colb	Noninterestincomeexcludingrevenuefromcontractswithcustomers Noninterestincomeexcludingrevenuefromcontractswithcustomers	16705000	USD
	colb	Noninterestincomeexcludingrevenuefromcontractswithcustomers Noninterestincomeexcludingrevenuefromcontractswithcustomers	31761000	USD
CY2021Q2	us-gaap	Noninterest Income NoninterestIncome	22730000	USD
CY2020Q2	us-gaap	Noninterest Income NoninterestIncome	37259000	USD
	us-gaap	Noninterest Income NoninterestIncome	45896000	USD
	us-gaap	Noninterest Income NoninterestIncome	58466000	USD

Files In Submission

Name	View Source	Status
0000887343-21-000155-index-headers.html	Edgar Link	pending
0000887343-21-000155-index.html	Edgar Link	pending
0000887343-21-000155.txt	Edgar Link	pending
0000887343-21-000155-xbrl.zip	Edgar Link	pending
colb-20210630.htm	Edgar Link	pending
colb-20210630.xsd	Edgar Link	pending
colb-20210630_cal.xml	Edgar Link	unprocessable
colb-20210630_def.xml	Edgar Link	unprocessable
colb-20210630_htm.xml	Edgar Link	completed
colb-20210630_lab.xml	Edgar Link	unprocessable
colb-20210630_pre.xml	Edgar Link	unprocessable
colb2q2021ex311.htm	Edgar Link	pending
colb2q2021ex312.htm	Edgar Link	pending
colb2q2021ex32.htm	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
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$COLB
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2021 Q2 Form 10-Q Financial Statement

#000088734321000155 Filed on August 06, 2021

Income Statement

Balance Sheet

Cashflow Statement

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$COLB Columbia Banking System Inc Stock $colb

2021 Q2 Form 10-Q Financial Statement

#000088734321000155 Filed on August 06, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$COLB
Columbia Banking System Inc Stock $colb