XML 56 R42.htm IDEA: XBRL DOCUMENT v3.19.2

Securities (Carrying Value of Securities Pledged as Collateral) (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Restricted	$ 489,515
Washington and Oregon State Public Deposits [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Restricted	280,968
Federal Reserve Bank Advances [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Restricted	52,329
Other Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Restricted	$ 156,218

X

- Definition

Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleRestricted
Namespace Prefix:	us-gaap_
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_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	colb_SecuritiesPledgedAsCollateralByCounterpartyAxis=colb_WashingtonAndOregonStatePublicDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	colb_SecuritiesPledgedAsCollateralByCounterpartyAxis=us-gaap_FederalReserveBankAdvancesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	colb_SecuritiesPledgedAsCollateralByCounterpartyAxis=colb_OtherSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: