Fair Value - Impaired Loans Held-for-investment - Additional Disclosures (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Impaired Loans Held-for-investment
Impaired loans held-for-investment	$ 3,816	$ 3,190
Additional provision (credit) for loan losses	228	320
Valuation allowance on foreclosed assets		0
Partial charge-offs		0
Carrying amount
Impaired Loans Held-for-investment
Foreclosed assets	0	229
Carried at fair value
Impaired Loans Held-for-investment
Impaired loans held-for-investment	1,556	1,112
Specific valuation allowance	242	329
Portion carried at cost
Impaired Loans Held-for-investment
Impaired loans held-for-investment	$ 2,260	$ 2,078

This element represents the fair value of investment of impaired financing receivables net of related allowance for credit losses.

No definition available.

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

This element represents the fair value of allowance for credit losses related to recorded investment.

No definition available.

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

Fair value of foreclosed assets.

No definition available.

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

Represents the amount of valuation allowance on foreclosed assets as of the balance sheet date.

No definition available.

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

Represents the additional provision for loan losses because of partial charge-offs and changes in specific valuation allowance during the period.

No definition available.

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

Represents the amount of loans that have been partially charged-off from loan receivables.

No definition available.

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

No definition available.

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

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
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Balance Type:
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Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_PortionAtOtherThanFairValueFairValueDisclosureMember
Namespace Prefix:
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