CommunityOne Bancorp (Parent Company) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets
Other assets				$ 32,648	$ 23,434
Total Assets				2,397,265	2,215,514
Liabilities and shareholders’ equity
Borrowed funds				127,298	130,274
Shareholders’ equity				273,038	266,916	$ 80,361	$ 98,445
Total Liabilities and Shareholders' Equity				2,397,265	2,215,514
Condensed Statements of Operations
Noninterest income	$ 18,170	$ 17,364	$ 20,414
Interest expense	(10,185)	(10,090)	(10,559)
Noninterest expense	(75,488)	(78,535)	(84,481)
Loss before tax (benefit) expense	14,038	7,966	(157)
Income tax expense (benefit)	7,124	(142,492)	1,326
Net income (loss)	6,914	150,458	(1,483)
Cash flows from operating activities
Net loss	6,914	150,458	(1,483)
Adjustments to reconcile net income to net cash provided by operating activities:
Net cash provided by (used in) operating activities	(598)	781	(4,487)
Cash flows from investing activities
Net cash used in investing activities	(174,057)	(40,136)	(23,080)
Cash flows from financing activities
Proceeds from issuance of common stock, net of costs	0	24,982	0
Net cash provided by (used) in financing activities	117,948	67,807	(144,613)
Net (Decrease) Increase in Cash and Cash Equivalents	(56,707)	28,452	(172,180)
Parent Company [Member]
Assets
Cash	6,032	637	606	1,195	6,032	$ 637	$ 606
Investment in subsidiaries				330,089	322,615
Other assets				4,910	3,678
Total Assets				336,194	332,325
Liabilities and shareholders’ equity
Accrued liabilities				6,454	8,707
Borrowed funds				56,702	56,702
Shareholders’ equity				273,038	266,916
Total Liabilities and Shareholders' Equity				$ 336,194	$ 332,325
Condensed Statements of Operations
Noninterest income	34	33	31
Interest expense	(1,135)	(1,146)	(1,092)
Noninterest expense	(2,712)	(1,011)	(742)
Loss before tax (benefit) expense	(3,813)	(2,124)	(1,803)
Income tax expense (benefit)	(306)	(3,180)	0
Loss before equity in undistributed net loss of subsidiaries	(3,507)	1,056	(1,803)
Equity in undistributed net loss of subsidiaries	(10,421)	(149,402)	(320)
Net income (loss)	6,914	150,458	(1,483)
Cash flows from operating activities
Net loss	6,914	150,458	(1,483)
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed net loss of subsidiaries	(10,421)	(149,402)	(320)
Other, net	(3,485)	(2,095)	1,153
Net cash provided by (used in) operating activities	(6,992)	(1,039)	(650)
Cash flows from investing activities
Downstream cash investment in subsidiary	0	(19,400)	0
Net cash used in investing activities	0	(19,400)	0
Cash flows from financing activities
Proceeds from issuance of common stock, net of costs	2,155	24,982	0
Other	0	852	681
Net cash provided by (used) in financing activities	2,155	25,834	681
Net (Decrease) Increase in Cash and Cash Equivalents	(4,837)	5,395	31
Cash at beginning of period	6,032	637	606
Cash at end of period	$ 1,195	$ 6,032	$ 637