Income Taxes - Components of Low Income Housing Investment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Income Taxes
Low income housing tax credits	$ 439	$ 459
Low income housing investment losses	$ 460	$ 282

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

No definition available.

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