Loans - Troubled Debt Restructurings (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Loans
Recorded investment of troubled debt restructurings	$ 750,000	$ 325,000
Troubled debt restructurings, nonaccrual loans	99,000	16,000
Troubled debt restructurings, accruing loans	651,000	309,000
Specific reserves	$ 77,000	$ 2,000

Represents the amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings and are on nonaccrual status as of the balance sheet date.

No definition available.

+ Details

Name:	htbk_FinancingReceivableModificationsRecordedInvestmentNonaccrualStatus
Namespace Prefix:	htbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings and are still accruing as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	htbk_FinancingReceivableModificationsRecordedInvestmentStillAccruing
Namespace Prefix:	htbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of allowance for credit losses related to receivables which had been measured under a general allowance for credit losses methodology that are now identified as troubled debt restructurings.

+ References

No definition available.

+ Details

Name:	us-gaap_AllowanceForCreditLossesChangeInMethodOfCalculatingImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18845-111554

+ Details

Name:	us-gaap_FinancingReceivableModificationsRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LoansAndLeasesReceivableDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration