XML 51 R42.htm IDEA: XBRL DOCUMENT
v3.22.1

Business Combinations and Asset Acquisitions - Narrative (Details) - USD ($) $ in Thousands |  | 3 Months Ended
--- | --- | ---
Oct. 01, 2021 | Mar. 31, 2022 | Mar. 31, 2021
Bank of Commerce |  |  |
Business Acquisition [Line Items] |  |  |
Business Combination, Purchase Price Allocation, Goodwill Amount | $ 57,330 |  |
Business Combination, Purchase Price Allocation, Amortizable Intangible Assets | 15,932 |  |
Business Combination, net loans acquired | 1,084,984 |  |
Acquired PCD loans | $ 40,278 |  |
Business Combination, Acquisition Related Costs |  | $ 2,587 | $ 0
Umpqua |  |  |
Business Acquisition [Line Items] |  |  |
Business Combination, Acquisition Related Costs |  | $ 4,500 |

X
- Definition Business Combination, Purchase Price Allocation Amortizable Intangible Assets + References No definition available. + Details
Name: | colb_BusinessCombinationPurchasePriceAllocationAmortizableIntangibleAssets
Namespace Prefix: | colb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of goodwill arising from a business combination, which is the excess of the cost of the acquired entity over the amounts assigned to assets acquired and liabilities assumed. + References No definition available. + Details
Name: | colb_BusinessCombinationPurchasePriceAllocationGoodwillAmount
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_BusinessAcquisitionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of acquired receivable from business combination, excluding certain loans and debt securities acquired in transfer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=123413009&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationAcquiredReceivablesFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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
- Definition Amount at purchase price of financing receivable purchased with credit deterioration. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 19 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919265-210447 + Details
Name: | us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice
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_BusinessAcquisitionAxis=colb_UmpquaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |