Condensed Financial Statements Of Parent Company - Condensed Statements Of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements of Parent Company
Net income (loss)	$ 8,733	$ 10,269	$ 8,532	$ 7,365	$ 4,400	$ 6,954	$ 7,383	$ 7,332	$ 34,899	$ 26,069	$ 29,007
Stock-based compensation									3,213	3,324	3,141
Net cash provided by (used in) operating activities									43,542	34,123	27,271
Other									348		(1,976)
Net cash provided by (used in) investing activities									(250,654)	(320,255)	(243,370)
Proceeds from issuance of common stock									2,118	1,733	1,570
Taxes paid in net settlement of restricted stock									(891)	(1,207)	(1,045)
Net proceeds from issuance of subordinated notes payable										59,250
Dividends paid on common stock									(7,858)	(6,953)	(6,076)
Dividends paid on preferred stock										(463)	(574)
Other										450	556
Net cash used in financing activities									235,850	261,879	231,636
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									28,738	(24,253)	15,537
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD				67,312				91,565	67,312	91,565	76,028
CASH AND CASH EQUIVALENTS, END OF PERIOD	96,050				67,312				96,050	67,312	91,565
CoBiz Financial Inc.
Condensed Financial Statements of Parent Company
Net income (loss)									34,899	26,069	29,007
Equity in undistributed earnings of subsidiaries									(29,934)	(19,557)	(22,644)
Stock-based compensation									631	620	584
Change in other assets and liabilities									2,509	(7,480)	2,205
Net cash provided by (used in) operating activities									8,105	(348)	9,152
Net advances (to) from subsidiaries									(2,162)	1,095	(3,372)
Other									(2,829)	(27)	(31)
Net cash provided by (used in) investing activities									(4,991)	1,068	(3,403)
Proceeds from issuance of common stock									2,118	1,733	1,570
Taxes paid in net settlement of restricted stock									(891)	(1,207)	(1,045)
Net proceeds from issuance of subordinated notes payable										59,250
Redemption of preferred stock										(57,366)
Dividends paid on common stock									(7,858)	(6,953)	(6,076)
Dividends paid on preferred stock										(463)	(574)
Other										(104)	129
Net cash used in financing activities									(6,631)	(5,110)	(5,996)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									(3,517)	(4,390)	(247)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD				$ 20,105				$ 24,495	20,105	24,495	24,742
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 16,588				$ 20,105				$ 16,588	$ 20,105	$ 24,495