Amount of combined business value after business combination.

No definition available.

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- Definition

Number of business banking franchises acquired.

+ References

No definition available.

+ Details

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Data Type:	xbrli:decimalItemType
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- Definition

Number of loan classified as PCI loan.

+ References

No definition available.

+ Details

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Namespace Prefix:	htbk_
Data Type:	xbrli:integerItemType
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- Definition

Severance and retention acquisition costs incurred during the period.

+ References

No definition available.

+ Details

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

- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=116868678&loc=d3e1043-128460

+ Details

Name:	us-gaap_BusinessCombinationAcquisitionRelatedCosts
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Balance Type:	debit
Period Type:	duration

- Definition

Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessCombinationIntegrationRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

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Balance Type:	credit
Period Type:	instant

Business Combinations (Details)	3 Months Ended							12 Months Ended
Business Combinations (Details)	Dec. 31, 2019 USD ($) company loan	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($) loan	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) company loan	Dec. 31, 2018 USD ($) loan	Dec. 31, 2017 USD ($)
Business Combinations
Number of business banking franchises acquired \| company	3							3
Combined business value after business combination	$ 4,100,000,000							$ 4,100,000,000
Other merger-related costs								4,500,000	$ 5,598,000	$ 671,000
Salaries and employee benefits merger-related costs								6,580,000	3,569,000
Pre-tax acquisition costs	$ 9,879,000	$ 661,000	$ 540,000	$ 139,000	$ 199,000	$ 8,214,000	$ 615,000	$ 11,080,000	$ 9,167,000	$ 671,000
Number of loan classified as PCI loan \| loan	0			0				0	0
Total with an allowance recorded, Allowance for Loan Losses Allocated	$ 1,835,000			$ 6,944,000				$ 1,835,000	$ 6,944,000