Summary of Significant Accounting Policies (Details) - USD ($)	1 Months Ended	12 Months Ended
	Apr. 30, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Nov. 30, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Assets		$ 9,224,097,000	$ 8,798,536,000
Loan threshold for individual evaluation for impairment		$ 500,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]		Other assets
Operating Lease, Liability, Statement of Financial Position [Extensible List]		Other Liabilities	Other Liabilities
Unrecognized tax benefits		$ 0	$ 0
Income tax penalties and interest expense		0	0	$ 0
Equity securities, at fair value		2,710,000	5,418,000
Stockholders' equity		1,079,081,000	1,011,287,000	982,517,000		$ 972,060,000
Variable Interest Entity, Not Primary Beneficiary
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Assets					$ 7,000,000
Cumulative Effect, Period of Adoption, Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Stockholders' equity						0
Retained Earnings
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Stockholders' equity		$ 765,133,000	673,084,000	$ 615,481,000		560,216,000
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Stockholders' equity						548,000
Buildings
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Property, plant and equipment, useful life		40 years
Minimum
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Defined contribution plan, employer matching contribution, percent of match		3.00%
Minimum | Land and building improvements
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Property, plant and equipment, useful life		10 years
Minimum | Furniture and equipment
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Property, plant and equipment, useful life		3 years
Maximum
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Defined contribution plan, employer matching contribution, percent of match		4.50%
Maximum | Land and building improvements
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Property, plant and equipment, useful life		20 years
Maximum | Furniture and equipment
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Property, plant and equipment, useful life		10 years
Accounting Standards Update 2016-01 | Cumulative Effect, Period of Adoption, Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Equity securities, at fair value						1,900,000
Accounting Standards Update 2016-01 | Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Stockholders' equity						$ 548,000
Stewardship Statutory Trust I
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Ownership percentage by parent					100.00%
Columbia Bank Employee Stock Ownership Plan
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Loan term	20 years	20 years
Stewardship Property
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Assets held-for-sale, long-lived, fair value disclosure			$ 1,900,000