v2.4.1.9

Loans (Analysis of Loan Portfolio by Major Types of Loans) (Details) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015 | Dec. 31, 2014 | Mar. 31, 2014 | Dec. 31, 2013
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Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Less: Unearned income on loans | $ (53,867)us-gaap_LoansAndLeasesReceivableDeferredIncome | $ (59,374)us-gaap_LoansAndLeasesReceivableDeferredIncome |  |
Recorded Investment | 5,450,895 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome | 5,445,378 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome |  |
Allowance for loan losses | (70,234)us-gaap_LoansAndLeasesReceivableAllowance | (69,569)us-gaap_LoansAndLeasesReceivableAllowance | (70,571)us-gaap_LoansAndLeasesReceivableAllowance | (72,454)us-gaap_LoansAndLeasesReceivableAllowance
Loans, net | 5,380,661 us-gaap_LoansAndLeasesReceivableNetReportedAmount | 5,375,809 us-gaap_LoansAndLeasesReceivableNetReportedAmount |  |
Loans held for sale | 3,545 us-gaap_LoansReceivableHeldForSaleNet | 1,116 us-gaap_LoansReceivableHeldForSaleNet |  |
Loans, Excluding Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Less: Unearned income on loans | (53,867)us-gaap_LoansAndLeasesReceivableDeferredIncome / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | (59,374)us-gaap_LoansAndLeasesReceivableDeferredIncome / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Recorded Investment | 5,231,056 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 5,214,794 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Allowance for loan losses | (53,703)us-gaap_LoansAndLeasesReceivableAllowance / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | (53,233)us-gaap_LoansAndLeasesReceivableAllowance / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Loans, net | 5,177,353 us-gaap_LoansAndLeasesReceivableNetReportedAmount / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 5,161,561 us-gaap_LoansAndLeasesReceivableNetReportedAmount / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Loans held for sale | 3,545 us-gaap_LoansReceivableHeldForSaleNet / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,116 us-gaap_LoansReceivableHeldForSaleNet / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross | 5,231,056 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 5,214,794 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Less: Unearned income on loans | 0 us-gaap_LoansAndLeasesReceivableDeferredIncome / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 0 us-gaap_LoansAndLeasesReceivableDeferredIncome / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Recorded Investment | 219,839 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 230,584 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Allowance for loan losses | (16,531)us-gaap_LoansAndLeasesReceivableAllowance / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | (16,336)us-gaap_LoansAndLeasesReceivableAllowance / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans, net | 203,308 us-gaap_LoansAndLeasesReceivableNetReportedAmount / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 214,248 us-gaap_LoansAndLeasesReceivableNetReportedAmount / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans held for sale | 0 us-gaap_LoansReceivableHeldForSaleNet / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 0 us-gaap_LoansReceivableHeldForSaleNet / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross | 243,111 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 256,468 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Acquisition Accounting Valuation Discount on Covered Loans | 23,272 colb_AcquisitionAccountingValuationDiscountOnCoveredLoans / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 25,884 colb_AcquisitionAccountingValuationDiscountOnCoveredLoans / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Commercial and Multifamily Residential Construction [Domain] | Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans and Leases Receivable, Gross | 2,501 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialandMultifamilyResidentialConstructionDomain / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 2,588 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialandMultifamilyResidentialConstructionDomain / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
One-to-Four Family Residential [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans and Leases Receivable, Gross, Consumer, Mortgage | 200,340 us-gaap_LoansAndLeasesReceivableConsumerMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember | 202,564 us-gaap_LoansAndLeasesReceivableConsumerMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember |  |
Loans and Leases Receivable, Gross, Consumer, Construction | 127,814 us-gaap_LoansAndLeasesReceivableConsumerConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember | 120,887 us-gaap_LoansAndLeasesReceivableConsumerConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember |  |
Allowance for loan losses | (1,364)us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember | (2,281)us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember | (1,194)us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember | (1,252)us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember
One-to-Four Family Residential [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans and Leases Receivable, Gross, Consumer, Mortgage | 173,739 us-gaap_LoansAndLeasesReceivableConsumerMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 175,571 us-gaap_LoansAndLeasesReceivableConsumerMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross, Consumer, Construction | 124,017 us-gaap_LoansAndLeasesReceivableConsumerConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 116,866 us-gaap_LoansAndLeasesReceivableConsumerConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross | 170,307 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 171,764 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
One-to-Four Family Residential [Member] | Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans and Leases Receivable, Gross, Consumer, Mortgage | 26,601 us-gaap_LoansAndLeasesReceivableConsumerMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 26,993 us-gaap_LoansAndLeasesReceivableConsumerMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross, Consumer, Construction | 3,797 us-gaap_LoansAndLeasesReceivableConsumerConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 4,021 us-gaap_LoansAndLeasesReceivableConsumerConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross | 31,127 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 31,981 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Commercial and Multifamily Residential [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable, Gross, Commercial, Mortgage | 2,492,684 us-gaap_LoansReceivableCommercialMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember | 2,492,310 us-gaap_LoansReceivableCommercialMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember |  |
Loans Receivable, Gross, Commercial, Construction | 122,118 us-gaap_LoansReceivableCommercialConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember | 136,764 us-gaap_LoansReceivableCommercialConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember |  |
Commercial and Multifamily Residential [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable, Gross, Commercial, Mortgage | 2,374,454 us-gaap_LoansReceivableCommercialMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 2,363,541 us-gaap_LoansReceivableCommercialMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Loans Receivable, Gross, Commercial, Construction | 119,880 us-gaap_LoansReceivableCommercialConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 134,443 us-gaap_LoansReceivableCommercialConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Commercial and Multifamily Residential [Member] | Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable, Gross, Commercial, Mortgage | 118,230 us-gaap_LoansReceivableCommercialMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 128,769 us-gaap_LoansReceivableCommercialMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans Receivable, Gross, Commercial, Construction | 2,238 us-gaap_LoansReceivableCommercialConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 2,321 us-gaap_LoansReceivableCommercialConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross | 127,952 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 140,398 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialAndMultifamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Commercial Portfolio Segment [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable, Gross, Commercial and Industrial | 2,186,208 us-gaap_LoansReceivableCommercialAndIndustrial / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 2,164,070 us-gaap_LoansReceivableCommercialAndIndustrial / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |  |
Commercial Portfolio Segment [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable, Gross, Commercial and Industrial | 2,139,873 us-gaap_LoansReceivableCommercialAndIndustrial / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 2,119,565 us-gaap_LoansReceivableCommercialAndIndustrial / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Commercial Portfolio Segment [Member] | Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable, Gross, Commercial and Industrial | 46,335 us-gaap_LoansReceivableCommercialAndIndustrial / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 44,505 us-gaap_LoansReceivableCommercialAndIndustrial / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross | 52,115 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 50,334 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Real Estate Portfolio Segment [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable Real Estate Mortgage | 2,693,024 colb_LoansReceivableRealEstateMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstatePortfolioSegmentMember | 2,694,874 colb_LoansReceivableRealEstateMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstatePortfolioSegmentMember |  |
Real Estate Portfolio Segment [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable Real Estate Mortgage | 2,548,193 colb_LoansReceivableRealEstateMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstatePortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 2,539,112 colb_LoansReceivableRealEstateMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstatePortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Real Estate Portfolio Segment [Member] | Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable Real Estate Mortgage | 144,831 colb_LoansReceivableRealEstateMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstatePortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 155,762 colb_LoansReceivableRealEstateMortgage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstatePortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross | 159,079 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstatePortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 172,379 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstatePortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
One-to-Four Family Residential Construction [Domain] | Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans and Leases Receivable, Gross | 4,026 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OnetoFourFamilyResidentialConstructionDomain / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 4,353 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OnetoFourFamilyResidentialConstructionDomain / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Real Estate Construction Portfolio Segment [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable Real Estate Construction | 249,932 colb_LoansReceivableRealEstateConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstateConstructionPortfolioSegmentMember | 257,651 colb_LoansReceivableRealEstateConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstateConstructionPortfolioSegmentMember |  |
Real Estate Construction Portfolio Segment [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable Real Estate Construction | 243,897 colb_LoansReceivableRealEstateConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstateConstructionPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 251,309 colb_LoansReceivableRealEstateConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstateConstructionPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Real Estate Construction Portfolio Segment [Member] | Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans Receivable Real Estate Construction | 6,035 colb_LoansReceivableRealEstateConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstateConstructionPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 6,342 colb_LoansReceivableRealEstateConstruction / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstateConstructionPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross | 6,527 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstateConstructionPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 6,941 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_RealEstateConstructionPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Consumer Portfolio Segment [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans and Leases Receivable, Gross, Consumer | 375,598 us-gaap_LoansAndLeasesReceivableConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 388,157 us-gaap_LoansAndLeasesReceivableConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  |
Allowance for loan losses | (2,835)us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | (3,180)us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | (2,637)us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | (2,547)us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Consumer Portfolio Segment [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans and Leases Receivable, Gross, Consumer | 352,960 us-gaap_LoansAndLeasesReceivableConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 364,182 us-gaap_LoansAndLeasesReceivableConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross | 336,158 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 345,032 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |  |
Consumer Portfolio Segment [Member] | Purchased Credit Impaired Loans [Member] |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans and Leases Receivable, Gross, Consumer | 22,638 us-gaap_LoansAndLeasesReceivableConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | 23,975 us-gaap_LoansAndLeasesReceivableConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |
Loans and Leases Receivable, Gross | $ 25,390 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember | $ 26,814 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_PurchasedCreditImpairedLoansMember |  |

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- Definition Loans Receivable Real Estate Construction + References No definition available. + Details
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- Definition Loans Receivable Real Estate Mortgage. + References No definition available. + Details
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- Definition Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(d)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph d -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (b)(1)(ii) -URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section L -Subsection 1 + Details
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- Definition Amount before allowance of consumer loans, including, but not limited to, mortgage, home equity, vehicles, credit card, installment, and lease financing. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph a, b -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(a),(b)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Amount before allowance of loans issued to build, improve or remodel a residential home. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph a, b -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(a)(2),(b)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Amount before allowance of consumer mortgage. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes subordinated loans such as home equity lines of credit and loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph a, b -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(a)(3),(b)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5074-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6378556&loc=d3e10152-111534 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=25496975&loc=d3e45377-112738 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Article 9 + Details
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- Definition Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 + Details
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- Definition Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5074-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 + Details
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- Definition Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Amount before allowance of loans issued to commercial and industrial institutions. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes real estate loans and loans covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5066-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(a)(1)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph a(1) -Article 9 + Details
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- Definition Amount before allowance of commercial construction loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5066-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph a -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(a)(2)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Amount before allowance of mortgage loans on existing land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5066-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(a)(3)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph a -Article 9 + Details
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