v2.4.0.8

Covered Assets and FDIC Loss-sharing Asset (Covered OREO at Carrying Value) (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2013 | Dec. 31, 2012
Covered Assets And FDIC Loss Sharing Asset [Line Items] |  |
Balance, end of period | $ 35,927 | $ 26,987
Covered Loans [Member] |  |
Covered Assets And FDIC Loss Sharing Asset [Line Items] |  |
Balance, beginning of period | 16,311 | 28,126
Transfers in | 8,827 | 14,166
Additional OREO write-downs | (282) | (3,484)
Proceeds from sale of OREO property | (22,046) | (33,315)
Gain on sale of OREO | 9,283 | 10,818
Balance, end of period | $ 12,093 | $ 16,311

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- Details
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Namespace Prefix: | colb_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Covered Oreo write downs. + References No definition available. + Details
Name: | colb_CoveredOreoWriteDowns
Namespace Prefix: | colb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Gain on sale of covered oreo. + References No definition available. + Details
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Namespace Prefix: | colb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Proceeds from sale of covered foreclosed assets. + References No definition available. + Details
Name: | colb_ProceedsFromSaleOfCoveredForeclosedAssets
Namespace Prefix: | colb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Real Estate Acquired Through Foreclosure Transfers In Net Of Write Downs + References No definition available. + Details
Name: | colb_RealEstateAcquiredThroughForeclosureTransfersInNetOfWriteDowns
Namespace Prefix: | colb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition No authoritative reference available. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4437-111522 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 28 -Article 12 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph c -Subparagraph Schedule III -Article 5 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant