Regulatory Capital Requirements (Tables)

12 Months Ended

Dec. 31, 2014

Regulatory Capital Requirements [Abstract]

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations

As of December 31, 2014, the most recent notification from the Federal Deposit Insurance Corporation 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 total risk-based, Tier 1 risk-based, and Tier 1 leverage ratios as set forth in the following tables. 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, 2014 and 2013, are also presented in the following table.

	Actual				For Capital Adequacy Purposes				To Be Well Capitalized Under Prompt Corrective Action Provision
	Amount		Ratio		Amount		Ratio		Amount		Ratio
	(dollars in thousands)
As of December 31, 2014
Total Capital (to risk-weighted assets):
The Company	$	890,029	14.13	%	$	503,989	8.0	%	N/A		N/A
Columbia Bank	$	860,755	13.67	%	$	503,852	8.0	%	$	629,816	10.0	%
Tier 1 Capital (to risk-weighted assets):
The Company	$	817,805	12.98	%	$	251,995	4.0	%	N/A		N/A
Columbia Bank	$	788,531	12.52	%	$	251,926	4.0	%	$	377,889	6.0	%
Tier 1 Capital (to average assets):
The Company	$	817,805	10.57	%	$	309,579	4.0	%	N/A		N/A
Columbia Bank	$	788,531	9.79	%	$	322,029	4.0	%	$	402,537	5.0	%
As of December 31, 2013
Total Capital (to risk-weighted assets):
The Company	$	760,349	14.68	%	$	414,300	8.0	%	N/A		N/A
Columbia Bank	$	700,099	13.52	%	$	414,238	8.0	%	$	517,797	10.0	%
Tier 1 Capital (to risk-weighted assets):
The Company	$	695,489	13.43	%	$	207,150	4.0	%	N/A		N/A
Columbia Bank	$	635,248	12.27	%	$	207,119	4.0	%	$	310,678	6.0	%
Tier 1 Capital (to average assets):
The Company	$	695,489	10.19	%	$	272,891	4.0	%	N/A		N/A
Columbia Bank	$	635,248	9.29	%	$	273,560	4.0	%	$	341,950	5.0	%