Regulatory Capital Requirements (Tables)

12 Months Ended

Dec. 31, 2020

Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations

As of December 31, 2020, the most recent notification from the FDIC categorized Columbia Bank as well-capitalized under the regulatory framework for prompt corrective action. To be categorized as well- capitalized, an institution must maintain minimum CET1 risk-based, Tier 1 risk-based, total risk-based and Tier 1 leverage ratios as set forth in the following table. There are no conditions or events since the notification that management believes have changed Columbia Bank’s category.

The Company and its banking subsidiary’s actual capital amounts and ratios as of December 31, 2020 and 2019 are presented in the following table:

	Actual				Minimum Required For Capital Adequacy Purposes				Minimum Required Plus Capital Conservation Buffer				To Be Well Capitalized Under Prompt Corrective Action Provision
	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
	(dollars in thousands)
December 31, 2020
CET1 Capital (to risk-weighted assets):
The Company	$	1,390,958	12.88	%	$	486,080	4.50	%	$	756,125	7.00	%	N/A		N/A
Columbia Bank	$	1,411,834	13.08	%	$	485,775	4.50	%	$	755,651	7.00	%	$	701,676	6.50	%
Tier 1 Capital (to risk-weighted assets):
The Company	$	1,390,958	12.88	%	$	648,107	6.00	%	$	918,152	8.50	%	N/A		N/A
Columbia Bank	$	1,411,834	13.08	%	$	647,700	6.00	%	$	917,576	8.50	%	$	863,601	8.00	%
Total Capital (to risk-weighted assets):
The Company	$	1,561,020	14.45	%	$	864,143	8.00	%	$	1,134,187	10.50	%	N/A		N/A
Columbia Bank	$	1,546,804	14.33	%	$	863,601	8.00	%	$	1,133,476	10.50	%	$	1,079,501	10.00	%
Tier 1 Capital Leverage (to average assets):
The Company	$	1,390,958	8.86	%	$	628,112	4.00	%	$	628,112	4.00	%	N/A		N/A
Columbia Bank	$	1,411,834	9.08	%	$	622,171	4.00	%	$	622,171	4.00	%	$	777,714	5.00	%
December 31, 2019
CET1 Capital (to risk-weighted assets):
The Company	$	1,317,202	12.45	%	$	476,260	4.50	%	$	740,849	7.00	%	N/A		N/A
Columbia Bank	$	1,318,044	12.46	%	$	475,913	4.50	%	$	740,310	7.00	%	$	687,430	6.50	%
Tier 1 Capital (to risk-weighted assets):
The Company	$	1,317,202	12.45	%	$	635,014	6.00	%	$	899,603	8.50	%	N/A		N/A
Columbia Bank	$	1,318,044	12.46	%	$	634,551	6.00	%	$	898,947	8.50	%	$	846,068	8.00	%
Total Capital (to risk-weighted assets):
The Company	$	1,439,877	13.60	%	$	846,685	8.00	%	$	1,111,274	10.50	%	N/A		N/A
Columbia Bank	$	1,405,422	13.29	%	$	846,068	8.00	%	$	1,110,464	10.50	%	$	1,057,585	10.00	%
Tier 1 Capital Leverage (to average assets):
The Company	$	1,317,202	10.17	%	$	517,938	4.00	%	$	517,938	4.00	%	N/A		N/A
Columbia Bank	$	1,318,044	10.22	%	$	515,797	4.00	%	$	515,797	4.00	%	$	644,746	5.00	%