XML 76 R66.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Fair Value Accounting and Measurement (Quantitative Information About Level 3 Fair Value Measurements) (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Sep. 30, 2017 | Sep. 30, 2016
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired loans | $ 843 | $ 2,304
OREO | 625 | 335
Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired loans | 843 | 2,304
OREO | 625 | 335
Collateral Pledged [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired loans | 715 | 943
Uncollateralized [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired loans | $ 128 | $ 1,361
Uncollateralized [Member] | Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs, Discount Rate | 7.75% | 2.85%
Uncollateralized [Member] | Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs, Discount Rate | 7.75% | 6.50%
Uncollateralized [Member] | Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs, Discount Rate | 7.75% | 3.85%

X
- Definition Impaired Loans, Financial Assets, Fair Value + References No definition available. + Details
Name: | colb_ImpairedLoansFinancialAssetsFairValue
Namespace Prefix: | colb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Other Real Estate Owned, Fair Value Disclosure + References No definition available. + Details
Name: | colb_OtherRealEstateOwnedFairValueDisclosure
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_FairValueInputsAssetsQuantitativeInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueInputsDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=us-gaap_CollateralPledgedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=us-gaap_UncollateralizedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_MarketApproachValuationTechniqueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=colb_ImpairedLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |