v2.4.1.9

Loans (Analysis of the Aged Loan Portfolio) (Details) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015 | Dec. 31, 2014
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Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | $ 31,828 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus | $ 31,352 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 5,171,371 us-gaap_FinancingReceivableRecordedInvestmentCurrent / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 5,158,985 us-gaap_FinancingReceivableRecordedInvestmentCurrent / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 23,760 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 14,656 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 3,661 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 8,415 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 436 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,386 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 27,857 us-gaap_FinancingReceivableRecordedInvestmentPastDue / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 24,457 us-gaap_FinancingReceivableRecordedInvestmentPastDue / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 31,828 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 31,352 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 5,231,056 us-gaap_LoansReceivableNet / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 5,214,794 us-gaap_LoansReceivableNet / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Secured Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | 17,240 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember | 16,552 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember
Secured Loans [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 2,024,277 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 2,004,418 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 11,910 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 5,137 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 1,874 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 6,149 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 58 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,372 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 13,842 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 12,658 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 17,240 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 16,552 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 2,055,359 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 2,033,628 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_SecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Unsecured Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | 189 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember | 247 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember
Unsecured Loans [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 78,351 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 79,661 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 492 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 185 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 120 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 67 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 679 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 185 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 189 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 247 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 79,219 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 80,093 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_UnsecuredLoansMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
One-to-Four Family Residential [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | 4,429 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember | 2,822 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember
One-to-Four Family Residential [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 164,962 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 167,197 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 771 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,700 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 124 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 45 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 21 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 916 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,745 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 4,429 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 2,822 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 170,307 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 171,764 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OneToFourFamilyResidentialMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Commercial Land [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | 1,616 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember | 821 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember
Commercial Land [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 186,904 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 187,470 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 4,303 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,454 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 355 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 34 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 264 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 4,922 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,488 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 1,616 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 821 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 193,442 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 189,779 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_CommercialLandMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Income Property Multifamily [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | 887 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember | 3,200 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember
Income Property Multifamily [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 1,305,595 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,294,982 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 2,502 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 3,031 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 560 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 786 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 3,062 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 3,817 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 887 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 3,200 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 1,309,544 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,301,999 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Owner Occupied [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | 1,995 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember | 3,826 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember
Owner Occupied [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 841,551 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 839,689 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 2,206 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 937 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 435 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 289 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 2,641 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,226 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 1,995 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 3,826 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 846,187 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 844,741 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Land And Acquisition [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | 871 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember | 95 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember
Land And Acquisition [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 15,860 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 15,462 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 67 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 953 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 67 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 953 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 871 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 95 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 16,798 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 16,510 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_LandAndAcquisitionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Residential Construction [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | 1,263 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember | 370 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember
Residential Construction [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 104,378 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 97,821 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 326 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 4 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 4 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 4 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 330 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 1,263 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 370 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 105,645 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 98,521 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_ResidentialConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Income Property Multifamily Construction [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 62,958 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 73,783 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 0 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 0 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 62,958 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 73,783 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_IncomePropertyMultifamilyConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Owner Occupied Construction [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | 470 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember |
Owner Occupied Construction [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 54,969 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 57,470 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 994 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 0 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 0 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 994 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 470 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 480 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | 55,439 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 58,944 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = colb_OwnerOccupiedConstructionMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Consumer Portfolio Segment [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Nonaccrual Loans | 2,868 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 2,939 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Consumer Portfolio Segment [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Current Loans | 331,566 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 341,032 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
30 - 59 Days Past Due | 1,509 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 933 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
60 - 89 Days Past Due | 193 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 118 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due | 22 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 10 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Total Past Due | 1,724 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 1,061 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Nonaccrual Loans | 2,868 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | 2,939 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember
Loans Receivable, Net | $ 336,158 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember | $ 345,032 us-gaap_LoansReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / colb_LoansByMajorCategoryAxis = colb_LoansExcludingPurchasedCreditImpairedLoansMember

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- Definition Financing receivables that are less than 60 days past due but more than 29 days past due. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524 + Details
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- Definition Financing receivables that are less than 90 days past due but more than 59 days past due. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524 + Details
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- Definition Financing receivables that are current. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524 + Details
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- Definition Financing receivables that are equal to or greater than 90 days past due. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524 + Details
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- Definition Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524 + Details
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- Definition Recorded Investment in financing receivables that are past due at the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524 + 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. Includes loans held for sale. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: 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 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)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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