XML 77 R64.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Business Combinations and Asset Acquisitions - acquisition-related expenses (Details) - Bank of Commerce - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Asset Acquisition [Line Items] |  |  |
Business Combination, Acquisition Related Costs | $ 10,370 | $ 0 | $ 0
Compensation and employee benefits [Member] |  |  |
Asset Acquisition [Line Items] |  |  |
Business Combination, Acquisition Related Costs | 4,875 | 0 | 0
Occupancy [Member] |  |  |
Asset Acquisition [Line Items] |  |  |
Business Combination, Acquisition Related Costs | 271 | 0 | 0
Data processing [Member] |  |  |
Asset Acquisition [Line Items] |  |  |
Business Combination, Acquisition Related Costs | 287 | 0 | 0
Legal and professional fees [Member] |  |  |
Asset Acquisition [Line Items] |  |  |
Business Combination, Acquisition Related Costs | 4,429 | 0 | 0
Advertising and promotion [Member] |  |  |
Asset Acquisition [Line Items] |  |  |
Business Combination, Acquisition Related Costs | 9 | 0 | 0
Other noninterest expenses [Member] |  |  |
Asset Acquisition [Line Items] |  |  |
Business Combination, Acquisition Related Costs | $ 499 | $ 0 | $ 0

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_AssetAcquisitionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=123586518&loc=d3e1043-128460 + Details
Name: | us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=colb_BankOfCommerceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=colb_CompensationandemployeebenefitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=us-gaap_OccupancyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=colb_DataprocessingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=colb_LegalandprofessionalfeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=colb_AdvertisingandpromotionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=colb_OthernoninterestexpensesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |