Income Taxes - Components of Low Income Housing Investment (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Income Taxes
Low income housing tax credits	$ 511,000	$ 425,000
Low income housing investment expense	$ 520,000	$ 437,000

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