Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 31, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2015
Document Period End Date	Sep. 30, 2015
Current Fiscal Year End Date	--12-31
Entity Registrant Name	CommunityOne Bancorp
Entity Central Index Key	0000764811
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		24,292,179