Income Taxes - Components of Low Income Housing Investment (Details) - USD ($)	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Income Taxes
Low income housing tax credits	$ 210,000	$ 106,000
Low income housing investment expense	$ 211,000	$ 109,000

Represents information pertaining to investment expense on income tax housing investment.

No definition available.

Name:	htbk_EstimatedInvestmentGainLossOnIncomeTaxHousingInvestments
Namespace Prefix:	htbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration