CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock Tri Valley Bank	Common Stock United American Bank	Common Stock Presidio bank	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income / (Loss)	Tri Valley Bank	United American Bank	Presidio bank	Total
Balance at Dec. 31, 2016				$ 215,237	$ 52,527	$ (7,914)				$ 259,850
Balance (in shares) at Dec. 31, 2016				37,941,007
Increase (Decrease) in Shareholders' Equity
Net income					23,828					23,828
Other comprehensive income (loss)						(319)				(319)
Issuance of restricted stock awards, net (in shares)				64,136
Amortization of restricted stock awards, net of forfeitures and taxes				$ 912						912
Cash dividend declared					(15,238)					(15,238)
Reclassification associated with the Adoption of ASU 2018-02					1,019	(1,019)
Stock option expense, net of forfeitures				838						838
Stock options exercised				$ 1,368						1,368
Stock options exercised (in shares)				195,740
Balance at Dec. 31, 2017				$ 218,355	62,136	(9,252)				271,239
Balance (in shares) at Dec. 31, 2017				38,200,883
Increase (Decrease) in Shareholders' Equity
Net income					35,331					35,331
Other comprehensive income (loss)						(3,129)				(3,129)
Issuance of common shares to acquire Business	$ 30,725	$ 47,280					$ 30,725	$ 47,280
Issuance of common shares to acquire Business (in shares)	1,889,613	2,826,032
Issuance of restricted stock awards, net (in shares)				95,378
Amortization of restricted stock awards, net of forfeitures and taxes				$ 1,109						1,109
Cash dividend declared					(18,464)					(18,464)
Stock option expense, net of forfeitures				708						708
Stock options exercised				$ 2,667						2,667
Stock options exercised (in shares)				276,844
Balance at Dec. 31, 2018				$ 300,844	79,003	(12,381)				367,466
Balance (in shares) at Dec. 31, 2018				43,288,750
Increase (Decrease) in Shareholders' Equity
Net income					40,461					40,461
Other comprehensive income (loss)						2,603				2,603
Issuance of common shares to acquire Business			$ 177,926						$ 177,926
Issuance of common shares to acquire Business (in shares)			15,684,064
Consideration for Presidio stock options exchanged for Heritage Commerce Corp stock options			$ 7,426						$ 7,426
Issuance of restricted stock awards, net (in shares)				128,653
Amortization of restricted stock awards, net of forfeitures and taxes				$ 1,283						1,283
Cash dividend declared					(22,723)					(22,723)
Stock option expense, net of forfeitures and taxes				640						640
Stock options exercised				$ 1,626						1,626
Stock options exercised (in shares)				266,689
Balance at Dec. 31, 2019				$ 489,745	$ 96,741	$ (9,778)				$ 576,708
Balance (in shares) at Dec. 31, 2019				59,368,156