Income Taxes - Future Commitments of the Low Income Housing Investments (Details) - Low income housing investments $ in Thousands	Dec. 31, 2017 USD ($)
Future Commitments
2018	$ 14
2019	14
2020 through 2023	$ 274

Minimum amount of other commitment maturing after the second fiscal year following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

No definition available.

Name:	htbk_OtherCommitmentDueAfterSecondYear
Namespace Prefix:	htbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant