Premises and Equipment - Depreciation and Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Premises and Equipment
Depreciation and amortization	$ 786	$ 763	$ 685

The aggregate expense recognized in the current period that allocates the cost of tangible assets or depleting assets to periods that benefit from use of the assets.

No definition available.

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