XML 54 R44.htm IDEA: XBRL DOCUMENT
v3.4.0.3

Loans Loans (Analysis of Troubled Debt Restructurings) (Details) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2016 USD ($) Modifications | Mar. 31, 2015 USD ($) Modifications | Dec. 31, 2015 USD ($)
Financing Receivable, Modifications [Line Items] |  |  |
Financing Receivable Modifications Additional Commitment To Lend | $ 7 |  | $ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Financing Receivable, Modifications, Number of Contracts | Modifications | 8 | 0 |
Financing Receivable, Modifications, Pre-Modification Recorded Investment | $ 2,117 | $ 0 |
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 2,117 | $ 0 |
Loans, Excluding Purchased Credit Impaired Loans [Member] | Secured Loans [Member] |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Financing Receivable, Modifications, Number of Contracts | Modifications | 3 | 0 |
Financing Receivable, Modifications, Pre-Modification Recorded Investment | $ 1,370 | $ 0 |
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 1,370 | $ 0 |
Loans, Excluding Purchased Credit Impaired Loans [Member] | Owner Occupied [Member] |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Financing Receivable, Modifications, Number of Contracts | Modifications | 1 | 0 |
Financing Receivable, Modifications, Pre-Modification Recorded Investment | $ 250 | $ 0 |
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 250 | $ 0 |
Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer Portfolio Segment [Member] |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Financing Receivable, Modifications, Number of Contracts | Modifications | 4 | 0 |
Financing Receivable, Modifications, Pre-Modification Recorded Investment | $ 497 | $ 0 |
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 497 | $ 0 |

X
- Definition Financing Receivable Modifications Additional Commitment To Lend + References No definition available. + Details
Name: | colb_FinancingReceivableModificationsAdditionalCommitmentToLend
Namespace Prefix: | colb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FinancingReceivableModificationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Post-modification amount of investment in financing receivables modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Pre-modification amount of investment in financing receivables modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | colb_LoansByMajorCategoryAxis=colb_LoansExcludingPurchasedCreditImpairedLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=colb_SecuredLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=colb_OwnerOccupiedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |