Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2016
Basis of Presentation
Basis of Presentation	Basis of Presentation The unaudited consolidated financial statements of Heritage Commerce Corp (the "Company" or "HCC") and its wholly owned subsidiary, Heritage Bank of Commerce ("HBC"), have been prepared pursuant to the rules and regulations for reporting on Form 10-Q. Accordingly, certain information and notes required by accounting principles generally accepted in the United States of America ("GAAP") for annual financial statements are not included herein. The interim statements should be read in conjunction with the consolidated financial statements and notes that were included in the Company's Form 10-K for the year ended December 31, 2015. The Company acquired BVF/CSNK Acquisition Corp., a Delaware corporation ("BVF/CSNK") on November 1, 2014, the parent company of CSNK Working Capital Finance Corp. dba Bay View Funding ("Bay View Funding"). BVF/CSNK was subsequently merged into Bay View Funding and Bay View Funding became a wholly owned subsidiary of HBC. The Company acquired Focus Business Bank ("Focus") on August 20, 2015. Focus was merged with HBC, with HBC as the surviving bank. Focus's results of operations have been included in the Company's results of operations beginning August 21, 2015. HBC is a commercial bank serving customers primarily located in Santa Clara, Alameda, Contra Costa, and San Benito counties of California. Bay View Funding provides business-essential working capital factoring financing to various industries throughout the United States. No customer accounts for more than 10 percent of revenue for HBC or the Company. With the acquisition of Bay View Funding, the Company now has two reportable segments consisting of Banking and Factoring. The Company's management uses segment results in its operating and strategic planning. In management's opinion, all adjustments necessary for a fair presentation of these consolidated financial statements have been included and are of a normal and recurring nature. All intercompany transactions and balances have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ significantly from these estimates. The results for the three and nine months ended September 30, 2016 are not necessarily indicative of the results expected for any subsequent period or for the entire year ending December 31, 2016.
Reclassifications	Reclassifications Certain reclassifications of prior year balances have been made to conform to the current year presentation. These reclassifications had no impact on the Company's consolidated financial position, results of operations or net change in cash and cash equivalents.
Adoption of New Accounting Standards	Adoption of New Accounting Standards In September 2015, the FASB issued ASU No. 2015-16, Simplifying the Accounting for Measurement Period Adjustment. This update applies to all entities that have reported provisional amounts for items in a business combination for which the accounting is incomplete by the end of the reporting period in which the combination occurs and during the measurement period have an adjustment to provisional amounts recognized. The amendments in this update require that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The amendments in this update require that the acquirer's record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The amendments in this update require an entity to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. The amendments in this update are effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The Company has evaluated the adoption of the new guidance and has determined it did not have a material impact on the consolidated financial statements. Newly Issued, but not yet Effective Accounting Standards In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments—Recognition and Measurement of Financial Assets and Liabilities. The new guidance is intended to improve the recognition and measurement of financial instruments by requiring: equity investments (other than equity method or consolidation) to be measured at fair value with changes in fair value recognized in net income; public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; separate presentation of financial assets and financial liabilities by measurement category and form of financial assets (i.e. securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements; eliminating the requirement to disclose the fair value of financial instruments measured at amortized cost for organizations that are not public business entities; eliminating the requirement for non-public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is to be required to be disclosed for financial instruments measured at amortized cost on the balance sheet; and requiring a reporting organization to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from the change in the instrument-specific credit risk (also referred to as "own credit") when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The new guidance is effective for public business entities for fiscal years beginning after December 15, 2017. We are currently evaluating the impact of adopting the new guidance on the consolidated financial statements, but it is not expected to have a material impact. In February 2016, the FASB issued ASU No. 2016-02, Leases. The standard requires a lessee to recognize assets and liabilities on the balance sheet for leases with lease terms greater than 12 months. A lessee should recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term. When measuring assets and liabilities arising from a lease, a lessee (and a lessor) should include payments to be made in optional periods only if the lessee is reasonably certain to exercise an option to extend the lease or not to exercise an option to terminate the lease. Similarly, optional payments to purchase the underlying asset should be included in the measurement of lease assets and lease liabilities only if the lessee is reasonably certain to exercise that purchase option. Reasonably certain is a high threshold that is consistent with and intended to be applied in the same way as the reasonably assured threshold in the previous leases guidance. In addition, also consistent with the previous leases guidance, a lessee (and a lessor) should exclude most variable lease payments in measuring lease assets and lease liabilities, other than those that depend on an index or a rate or are in substance fixed payments. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. If a lessee makes this election, it should recognize lease expense for such leases generally on a straight-line basis over the lease term. The new guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. We are currently evaluating the impact of adopting the new guidance on our consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation: Improvements to Employee Share-Based Payment Accounting. The standard is intended to simplify several areas of accounting for share-based compensation arrangements, including the income tax impact, classification on the statement of cash flows and forfeitures. All excess tax benefits and tax deficiencies (including tax benefits of dividends on share-based payment awards) should be recognized as income tax expense or benefit in the income statement. The tax effects of exercised or vested awards should be treated as discrete items in the reporting period in which they occur. An entity also should recognize excess tax benefits regardless of whether the benefit reduces taxes payable in the current period. Excess tax benefits should be classified along with other income tax cash flows as an operating activity. An entity can make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest (current GAAP) or account for forfeitures when they occur. The threshold to qualify for equity classification permits withholding up to the maximum statutory tax rates in the applicable jurisdictions. Cash paid by an employer when directly withholding shares for tax withholding purposes should be classified as a financing activity. A nonpublic entity can make an accounting policy election to apply a practical expedient to estimate the expected term for all awards with performance or service conditions that meet certain conditions. A nonpublic entity can make a one-time accounting policy election to switch from measuring all liability-classified awards at fair value to intrinsic value. The new guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016, and early adoption is permitted. We are currently evaluating the impact of adopting the new guidance on our consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments. The standard is the final guidance on the new current expected credit loss ("CECL") model. The amendments in this update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to estimate future credit loss estimates. As CECL encompasses all financial assets carried at amortized cost, the requirement that reserves be established based on an organization's reasonable and supportable estimate of expected credit losses extends to held-to-maturity ("HTM") debt securities. The update amends the accounting for credit losses on available-for-sale securities ("AFS"), whereby credit losses will be presented as an allowance as opposed to a write-down. In addition, CECL will modify the accounting for purchased loans with credit deterioration since origination, so that reserves are established at the date of acquisition for purchased loans. Lastly, the amendment requires enhanced disclosures on the significant estimates and judgments used to estimate credit losses, as well as on the credit quality and underwriting standards of an organization's portfolio. These disclosures require organizations to present the currently required credit quality disclosures disaggregated by the year of origination or vintage. The guidance allows for a modified retrospective approach with a cumulative effect adjustment to the balance sheet upon adoption (charge to retained earnings instead of the income statement). The new guidance is effective for public business entities for fiscal years, and interim periods within those years, beginning after December 15, 2019, and early adoption is permitted. We are currently evaluating the impact of adopting the new guidance on our consolidated financial statements.