Stockholders' Equity - Actual Capital Amounts and Ratios (Details) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Parent Company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital conservation buffer, ratio	2.50%
Actual, Amount
Total capital	$ 1,104,863	$ 1,070,361
Tier one capital	1,041,650	998,172
Common equity tier one capital	1,034,433	990,955
Tier one leverage capital	$ 1,041,650	$ 998,172
Ratio, Actual
Capital to risk weighted assets	0.1713	0.1854
Tier one risk based capital to risk weighted assets	0.1615	0.1729
Common equity tier one capital	0.1604	0.1717
Tier one leverage capital to average assets	0.1123	0.1138
Minimum Capital Adequacy Requirements, Amount
Capital required for capital adequacy	$ 515,924	$ 461,766
Tier one risk based capital required for capital adequacy	386,943	346,325
Common equity tier one capital required for capital adequacy	290,207	259,744
Tier one leverage capital required for capital adequacy	$ 370,909	$ 350,923
Minimum Capital Adequacy Requirements, Ratio
Capital required for capital adequacy to risk weighted assets	0.080	0.0800
Tier one risk based capital required for capital adequacy to risk weighted assets	0.0600	0.0600
Common equity tier one capital required for capital adequacy to risk weighted assets	0.045	0.0450
Tier one leverage capital required for capital adequacy to average assets	0.0400	0.0400
Minimum Capital Adequacy Requirements With Capital Conservation Buffer, Amount
Capital required for capital adequacy with capital buffer	$ 677,151	$ 606,068
Tier one risk based capital required for capital adequacy with capital buffer	548,170	490,627
Common equity tier one risk based capital required for capital adequacy with capital buffer	451,434	404,046
Tier one leverage capital required for capital adequacy with capital buffer to average assets	$ 370,909	$ 350,923
Minimum Capital Adequacy Requirements With Capital Conservation Buffer, Ratio
Capital required for capital adequacy with capital buffer to risk weighted assets	0.1050	0.1050
Tier one risk based capital required for capital adequacy with capital buffer to risk weighted assets	0.0850	0.0850
Common equity tier one risk based capital requirement for capital adequacy with capital buffer to risk weighted assets	0.0700	0.0700
Tier one leverage capital requirement for capital adequacy with capital buffer to average assets	4.00%	4.00%
Columbia Bank
Actual, Amount
Total capital	$ 962,137	$ 924,959
Tier one capital	898,935	852,897
Common equity tier one capital	898,935	852,897
Tier one leverage capital	$ 898,935	$ 852,897
Ratio, Actual
Capital to risk weighted assets	0.1539	0.1605
Tier one risk based capital to risk weighted assets	0.1438	0.1480
Common equity tier one capital	0.1438	0.1480
Tier one leverage capital to average assets	0.0980	0.0972
Minimum Capital Adequacy Requirements, Amount
Capital required for capital adequacy	$ 500,127	$ 460,944
Tier one risk based capital required for capital adequacy	375,095	345,708
Common equity tier one capital required for capital adequacy	281,322	259,281
Tier one leverage capital required for capital adequacy	$ 366,961	$ 350,815
Minimum Capital Adequacy Requirements, Ratio
Capital required for capital adequacy to risk weighted assets	0.0800	0.0800
Tier one risk based capital required for capital adequacy to risk weighted assets	0.0600	0.0600
Common equity tier one capital required for capital adequacy to risk weighted assets	0.0450	0.0450
Tier one leverage capital required for capital adequacy to average assets	0.0400	0.0400
Minimum Capital Adequacy Requirements With Capital Conservation Buffer, Amount
Capital required for capital adequacy with capital buffer	$ 656,417	$ 604,989
Tier one risk based capital required for capital adequacy with capital buffer	531,385	489,753
Common equity tier one risk based capital required for capital adequacy with capital buffer	437,611	403,326
Tier one leverage capital required for capital adequacy with capital buffer to average assets	$ 366,961	$ 350,815
Minimum Capital Adequacy Requirements With Capital Conservation Buffer, Ratio
Capital required for capital adequacy with capital buffer to risk weighted assets	0.1050	0.1050
Tier one risk based capital required for capital adequacy with capital buffer to risk weighted assets	0.0850	0.0850
Common equity tier one risk based capital requirement for capital adequacy with capital buffer to risk weighted assets	0.0700	0.0700
Tier one leverage capital requirement for capital adequacy with capital buffer to average assets	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount
Capital required to be well capitalized, amount	$ 625,159	$ 576,180
Tier one risk based capital required to be well capitalized, amount	500,127	460,944
Common equity tier one capital required to be well-capitalized, amount	406,353	374,517
Tier one leverage capital required to be well capitalized, amount	$ 458,701	$ 438,519
To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio
Capital required to be well capitalized to risk weighted assets, ratio	0.1000	0.1000
Tier one risk based capital required to be well capitalized to risk weighted assets, ratio	0.0800	0.0800
Common equity tier one capital required to be well-capitalized to risk weighted assets, ratio	0.0650	0.0650
Tier one leverage capital required to be well capitalized to average assets, ratio	0.0500	0.0500
Freehold Bank
Actual, Amount
Total capital	$ 41,549
Tier one capital	41,537
Common equity tier one capital	41,537
Tier one leverage capital	$ 41,537
Ratio, Actual
Capital to risk weighted assets	0.2287
Tier one risk based capital to risk weighted assets	0.2286
Common equity tier one capital	0.2286
Tier one leverage capital to average assets	0.1371
Minimum Capital Adequacy Requirements, Amount
Capital required for capital adequacy	$ 14,534
Tier one risk based capital required for capital adequacy	10,901
Common equity tier one capital required for capital adequacy	8,176
Tier one leverage capital required for capital adequacy	$ 12,118
Minimum Capital Adequacy Requirements, Ratio
Capital required for capital adequacy to risk weighted assets	0.0800
Tier one risk based capital required for capital adequacy to risk weighted assets	0.0600
Common equity tier one capital required for capital adequacy to risk weighted assets	0.0450
Tier one leverage capital required for capital adequacy to average assets	0.0400
Minimum Capital Adequacy Requirements With Capital Conservation Buffer, Amount
Capital required for capital adequacy with capital buffer	$ 19,076
Tier one risk based capital required for capital adequacy with capital buffer	15,443
Common equity tier one risk based capital required for capital adequacy with capital buffer	12,717
Tier one leverage capital required for capital adequacy with capital buffer to average assets	$ 12,118
Minimum Capital Adequacy Requirements With Capital Conservation Buffer, Ratio
Capital required for capital adequacy with capital buffer to risk weighted assets	0.1050
Tier one risk based capital required for capital adequacy with capital buffer to risk weighted assets	0.0850
Common equity tier one risk based capital requirement for capital adequacy with capital buffer to risk weighted assets	0.0700
Tier one leverage capital requirement for capital adequacy with capital buffer to average assets	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount
Capital required to be well capitalized, amount	$ 18,168
Tier one risk based capital required to be well capitalized, amount	14,534
Common equity tier one capital required to be well-capitalized, amount	11,809
Tier one leverage capital required to be well capitalized, amount	$ 15,147
To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio
Capital required to be well capitalized to risk weighted assets, ratio	0.1000
Tier one risk based capital required to be well capitalized to risk weighted assets, ratio	0.0800
Common equity tier one capital required to be well-capitalized to risk weighted assets, ratio	0.0650
Tier one leverage capital required to be well capitalized to average assets, ratio	0.0500