CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($)	Common Stock Tri Valley Bank	Common Stock United American Bank	Common Stock Presidio bank	Common Stock	Retained Earnings Adjustment	Retained Earnings	Accumulated Other Comprehensive Income / (Loss)	Tri Valley Bank	United American Bank	Presidio bank	Adjustment	Total
Balance at Dec. 31, 2017				$ 218,355,000		$ 62,136,000	$ (9,252,000)					$ 271,239,000
Balance (in shares) at Dec. 31, 2017				38,200,883
Increase (Decrease) in Shareholders' Equity
Net income						35,331,000						35,331,000
Other comprehensive income (loss)							(3,129,000)					(3,129,000)
Issuance of common shares to acquire Business	$ 30,725,000	$ 47,280,000						$ 30,725,000	$ 47,280,000
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				$ 1,109,000								1,109,000
Cash dividend declared						(18,464,000)						(18,464,000)
Stock option expense, net of forfeitures				708,000								708,000
Stock options exercised				$ 2,667,000								2,667,000
Stock options exercised (in shares)				276,844
Balance at Dec. 31, 2018				$ 300,844,000		79,003,000	(12,381,000)					367,466,000
Balance (in shares) at Dec. 31, 2018				43,288,750
Increase (Decrease) in Shareholders' Equity
Net income						40,461,000						40,461,000
Other comprehensive income (loss)							2,603,000					2,603,000
Issuance of common shares to acquire Business			$ 177,926,000							$ 177,926,000
Issuance of common shares to acquire Business (in shares)			15,684,064
Consideration for Presidio stock options exchanged for Heritage Commerce Corp stock options				$ 7,426,000								7,426,000
Issuance of restricted stock awards, net (in shares)				128,653
Amortization of restricted stock awards, net of forfeitures and taxes				$ 1,283,000								1,283,000
Cash dividend declared						(22,723,000)						(22,723,000)
Stock option expense, net of forfeitures				640,000								640,000
Stock options exercised				$ 1,626,000								1,626,000
Stock options exercised (in shares)				266,689
Balance at Dec. 31, 2019				$ 489,745,000	$ (6,062,000)	96,741,000	(9,778,000)				$ (6,062,000)	576,708,000
Balance (in shares) at Dec. 31, 2019				59,368,156
Increase (Decrease) in Shareholders' Equity
Net income						35,299,000						35,299,000
Other comprehensive income (loss)							(939,000)					(939,000)
Consideration for Presidio stock options exchanged for Heritage Commerce Corp stock options										$ 7,426,000
Issuance of restricted stock awards, net (in shares)				168,117
Amortization of restricted stock awards, net of forfeitures and taxes				$ 1,689,000								1,689,000
Cash dividend declared						(31,079,000)						(31,079,000)
Stock option expense, net of forfeitures and taxes				559,000								559,000
Stock options exercised				$ 1,714,000								1,714,000
Stock options exercised (in shares)				381,184
Balance at Dec. 31, 2020				$ 493,707,000		$ 94,899,000	$ (10,717,000)					$ 577,889,000
Balance (in shares) at Dec. 31, 2020				59,917,457