CommunityOne Bancorp (Parent Company) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assets
Other assets	$ 23,434	$ 23,336
Total Assets	2,215,514	1,985,032
Liabilities and shareholders’ equity
Borrowed funds	130,274	135,248
Shareholders’ equity	266,916	80,361	98,445	129,015
Total Liabilities and Shareholders' Equity	2,215,514	1,985,032
Condensed Statements of Operations
Noninterest income	17,364	20,414	21,958
Interest expense	(10,090)	(10,559)	(16,708)
Noninterest expense	(78,535)	(84,481)	(110,206)
Loss from continuing operations, before income taxes	7,966	(157)	(41,017)
Income tax expense/(benefit)	(142,492)	1,326	(1,039)
Net income (loss)	150,458	(1,483)	(40,005)
Cash flows from operating activities
Net loss	150,458	(1,483)	(40,005)
Adjustments to reconcile net income to net cash provided by operating activities:
Net cash used in operating activities	781	(4,487)	(35,961)
Cash flows from investing activities
Net cash (used in) provided by investing activities	(40,136)	(23,080)	(63,917)
Cash flows from financing activities
Issuance of common stock, net of expense	24,982	0	6,694
Net cash used in financing activities	67,807	(144,613)	(213,928)
Net (Decrease) Increase in Cash and Cash Equivalents	28,452	(172,180)	(313,806)
Parent Company [Member]
Assets
Cash	6,032	637	606
Investment in subsidiaries	322,615	143,683
Other assets	3,678	505
Total Assets	332,325	144,825
Liabilities and shareholders’ equity
Accrued liabilities	8,707	7,762
Borrowed funds	56,702	56,702
Shareholders’ equity	266,916	80,361
Total Liabilities and Shareholders' Equity	332,325	144,825
Condensed Statements of Operations
Noninterest income	33	31	34
Interest expense	(1,146)	(1,092)	(1,157)
Noninterest expense	(1,011)	(742)	(970)
Loss from continuing operations, before income taxes	(2,124)	(1,803)	(2,093)
Income tax expense/(benefit)	(3,180)	0	(311)
Loss before equity in undistributed net loss of subsidiaries	1,056	(1,803)	(1,782)
Equity in undistributed net loss of subsidiaries	(149,402)	(320)	38,223
Net income (loss)	150,458	(1,483)	(40,005)
Cash flows from operating activities
Net loss	150,458	(1,483)	(40,005)
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed net loss of subsidiaries	(149,402)	(320)	38,223
Other, net	(2,095)	1,153	503
Net cash used in operating activities	(1,039)	(650)	(1,279)
Cash flows from investing activities
Downstream cash investment in subsidiary	(19,400)	0	(6,709)
Net cash (used in) provided by investing activities	(19,400)	0	(6,709)
Cash flows from financing activities
Issuance of common stock, net of expense	24,982		6,694
Other	852	681	(908)
Net cash used in financing activities	25,834	681	5,786
Net (Decrease) Increase in Cash and Cash Equivalents	5,395	31	(2,202)
Cash at beginning of period	637	606	2,808
Cash at end of period	$ 6,032	$ 637	$ 606