Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details)	12 Months Ended
Dec. 31, 2018
Cash and Cash Equivalents
Period for which federal funds are sold and purchased	1 day

Represents the period for which federal funds are sold and purchased by the entity.

No definition available.

Name:	htbk_PeriodForWhichFederalFundsAreSoldAndPurchased
Namespace Prefix:	htbk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration