v2.4.1.9

Loans Loans (Analysis of Troubled Debt Restructurings) (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended |
--- | --- | ---
Mar. 31, 2015 Modifications | Mar. 31, 2014 Modifications | Dec. 31, 2014
Financing Receivable, Modifications [Line Items] |  |  |
Financing Receivable Modifications Additional Commitment To Lend | 0 colb_FinancingReceivableModificationsAdditionalCommitmentToLend |  | $ 0 colb_FinancingReceivableModificationsAdditionalCommitmentToLend
Loans, Excluding Purchased Credit Impaired Loans [Member] |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Number of TDR Modifications | 0 colb_FinancingReceivableModificationsNumberOfContractsDuration / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 5 colb_FinancingReceivableModificationsNumberOfContractsDuration / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Pre-Modification Outstanding Recorded Investment |  | 1,183 colb_FinancingReceivableModificationsPreModificationRecordedInvestmentDuration / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Post-Modification Outstanding Recorded Investment |  | 1,166 colb_FinancingReceivableModificationsPostModificationRecordedInvestmentDuration / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Loans, Excluding Purchased Credit Impaired Loans [Member] | Secured Loans [Member] |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Number of TDR Modifications |  | 2 colb_FinancingReceivableModificationsNumberOfContractsDuration / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Pre-Modification Outstanding Recorded Investment |  | 546 colb_FinancingReceivableModificationsPreModificationRecordedInvestmentDuration / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Post-Modification Outstanding Recorded Investment |  | 546 colb_FinancingReceivableModificationsPostModificationRecordedInvestmentDuration / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Loans, Excluding Purchased Credit Impaired Loans [Member] | One-to-Four Family Residential [Member] |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Number of TDR Modifications |  | 2 colb_FinancingReceivableModificationsNumberOfContractsDuration / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Pre-Modification Outstanding Recorded Investment |  | 494 colb_FinancingReceivableModificationsPreModificationRecordedInvestmentDuration / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Post-Modification Outstanding Recorded Investment |  | 494 colb_FinancingReceivableModificationsPostModificationRecordedInvestmentDuration / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Loans, Excluding Purchased Credit Impaired Loans [Member] | Income Property Multifamily [Member] |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Number of TDR Modifications |  | 1 colb_FinancingReceivableModificationsNumberOfContractsDuration / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Pre-Modification Outstanding Recorded Investment |  | 143 colb_FinancingReceivableModificationsPreModificationRecordedInvestmentDuration / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |
Post-Modification Outstanding Recorded Investment |  | $ 126 colb_FinancingReceivableModificationsPostModificationRecordedInvestmentDuration / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember |

X
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Namespace Prefix: | colb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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X
- Definition Financing Receivable, Modifications, Number of Contracts, Duration + References No definition available. + Details
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Balance Type: | na
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- Definition Financing Receivable, Modifications, Pre-Modification Recorded Investment, Duration + References No definition available. + Details
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Namespace Prefix: | colb_
Data Type: | xbrli:monetaryItemType
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Period Type: | duration

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- Details
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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |