Regulatory Capital Requirements (Tables)

12 Months Ended

Dec. 31, 2019

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

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations

As of December 31, 2019, 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, 2019 and 2018 are presented in the following table:



	Actual				Minimum Required For Capital Adequacy Purposes				Minimum Required Plus Capital Conservation Buffer Phase-In				Minimum Required Plus Capital Conservation Buffer Fully Phased-In				To Be Well Capitalized Under Prompt Corrective Action Provision
	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
	(dollars in thousands)
December 31, 2019
CET1 Capital (to risk-weighted assets):
The Company	$	1,317,202	12.45	%	$	476,260	4.50	%	N/A		N/A		$	740,849	7.00	%	N/A		N/A
Columbia Bank	$	1,318,044	12.46	%	$	475,913	4.50	%	N/A		N/A		$	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	%	N/A		N/A		$	899,603	8.50	%	N/A		N/A
Columbia Bank	$	1,318,044	12.46	%	$	634,551	6.00	%	N/A		N/A		$	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	%	N/A		N/A		$	1,111,274	10.50	%	N/A		N/A
Columbia Bank	$	1,405,422	13.29	%	$	846,068	8.00	%	N/A		N/A		$	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	%	N/A		N/A		$	517,938	4.00	%	N/A		N/A
Columbia Bank	$	1,318,044	10.22	%	$	515,797	4.00	%	N/A		N/A		$	515,797	4.00	%	$	644,746	5.00	%
December 31, 2018
CET1 Capital (to risk-weighted assets):
The Company	$	1,253,394	12.74	%	$	442,717	4.50	%	$	627,182	6.38	%	$	688,670	7.00	%	N/A		N/A
Columbia Bank	$	1,274,317	12.96	%	$	442,552	4.50	%	$	626,948	6.38	%	$	688,414	7.00	%	$	639,241	6.50	%
Tier 1 Capital (to risk-weighted assets):
The Company	$	1,253,394	12.74	%	$	590,289	6.00	%	$	774,754	7.88	%	$	836,243	8.50	%	N/A		N/A
Columbia Bank	$	1,274,317	12.96	%	$	590,069	6.00	%	$	774,465	7.88	%	$	835,931	8.50	%	$	786,759	8.00	%
Total Capital (to risk-weighted assets):
The Company	$	1,376,555	13.99	%	$	787,052	8.00	%	$	971,517	9.88	%	$	1,033,006	10.50	%	N/A		N/A
Columbia Bank	$	1,362,016	13.85	%	$	786,759	8.00	%	$	971,155	9.88	%	$	1,032,621	10.50	%	$	983,448	10.00	%
Tier 1 Capital Leverage (to average assets):
The Company	$	1,253,394	10.24	%	$	489,399	4.00	%	$	489,399	4.00	%	$	489,399	4.00	%	N/A		N/A
Columbia Bank	$	1,274,317	10.42	%	$	489,254	4.00	%	$	489,254	4.00	%	$	489,254	4.00	%	$	611,567	5.00	%