XML 64 R103.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Fair Value Accounting and Measurement (Quantitative Information About Level 3 Fair Value Measurements) (Details) - Fair Value, Nonrecurring [Member] $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired loans | $ 10,007 | $ 11,555
Fair Value, Option, Changes in Fair Value, Gain (Loss) | (7,519) | (1,821)
Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired loans | 10,007 | 11,555
Impaired Loans [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value, Option, Changes in Fair Value, Gain (Loss) | (7,519) | (1,821)
Uncollateralized [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired loans |  | $ 3,161
Uncollateralized [Member] | Valuation, Market Approach [Member] | Impaired Loans [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired Loans, Measurement Input |  | 0.0034
Uncollateralized [Member] | Valuation, Market Approach [Member] | Impaired Loans [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired Loans, Measurement Input |  | 0.0034
Uncollateralized [Member] | Valuation, Market Approach [Member] | Impaired Loans [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired Loans, Measurement Input |  | 0.0034
Collateral-Dependent [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired loans | $ 10,007 | $ 8,394
Collateral-Dependent [Member] | Valuation, Market Approach [Member] | Impaired Loans [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired Loans, Measurement Input | 0.0000 | 0.0000
Collateral-Dependent [Member] | Valuation, Market Approach [Member] | Impaired Loans [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired Loans, Measurement Input | 1.0000 | 0.7004
Collateral-Dependent [Member] | Valuation, Market Approach [Member] | Impaired Loans [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Impaired Loans, Measurement Input | 0.4968 | 0.0702

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 Value of input used to measure Impaired Loans. + References No definition available. + Details
Name: | colb_ImpairedLoansMeasurementInput
Namespace Prefix: | colb_
Data Type: | xbrli:decimalItemType
Balance Type: | na
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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 30 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612 + Details
Name: | us-gaap_FairValueOptionChangesInFairValueGainLoss1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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_FinancialInstrumentAxis=colb_ImpairedLoansMember
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: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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