XML 66 R57.htm IDEA: XBRL DOCUMENT v3.22.1

Allowance for Credit Losses and Allowance for Unfunded Commitments and Letters of Credit (Narrative) (Details)	3 Months Ended
	Mar. 31, 2022 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum loan balance of nonaccrual, collateral dependent loans considered for ACL	$ 500,000
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	$ (8,600,000)

X

- Definition

Minimum loan balance of nonaccrual, collateral dependent loans considered for ACL

+ References

No definition available.

+ Details

Name:	colb_MinimumloanbalanceofnonaccrualcollateraldependentloansconsideredforACL
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_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of increase (decrease) in allowance for credit loss on financing receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration