Equity Plan - Stock Option Activity (Details) - Options - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2020
Number of Shares
Outstanding at the beginning of the period (in shares)	2,712,846
Granted (in shares)	25,000
Heritage Commerce Corp stock options	2,505,523	2,505,523
Exercised (in shares)	(200,063)
Forfeited or expired (in shares)	(32,260)
Outstanding at the end of the period (in shares)	2,505,523
Vested or expected to vest (in shares)		2,355,192
Exercisable at the end of the period (in shares)		2,047,781
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 8.80
Granted (in dollars per share)	11.58
Heritage Commerce Corp stock options	9.03	$ 9.03
Exercised (in dollars per share)	5.53
Forfeited or expired (in dollars per share)	13.80
Outstanding at the end of the period (in dollars per share)	$ 9.03
Additional Information
Weighted Average Remaining Contractual Life - Outstanding at the end of the period (in years)	5 years 5 months 9 days
Weighted Average Remaining Contractual Life - Vested or expected to vest (in years)	5 years 5 months 9 days
Weighted Average Remaining Contractual Life - Exercisable at the end of the period (in years)	4 years 9 months
Aggregate Intrinsic Value - Outstanding at the end of the period (in dollars)		$ 3,087,857
Aggregate Intrinsic Value - Vested or expected to vest (in dollars)		2,902,585
Aggregate Intrinsic Value - Exercisable at the end of the period (in dollars)		$ 3,087,857
Presidio bank
Number of Shares
Heritage Commerce Corp stock options	1,176,757	1,176,757
Outstanding at the end of the period (in shares)	1,176,757