Basis of Presentation (Policies)	6 Months Ended
Basis of Presentation (Policies)	Jun. 30, 2018
Basis of Presentation
Basis of Presentation	1) 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, 2017. HBC is a commercial bank serving customers primarily located in Santa Clara, Alameda, Contra Costa, and San Benito counties of California. CSNK Working Capital Finance Corp. a California corporation, dba Bay View Funding (“Bay View Funding”) is a wholly owned subsidiary of HBC, and provides business-essential working capital factoring financing to various industries throughout the United States. No customer accounts for more than 10% of revenue for HBC or the Company. The Company reports its results for two segments: 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 six months ended June 30, 2018 are not necessarily indicative of the results expected for any subsequent period or for the entire year ending December 31, 2018.
Business Combinations	Business Combinations The Company accounts for acquisitions of businesses using the acquisition method of accounting. Under the acquisition method, assets acquired and liabilities assumed are recorded at their estimated fair values at the date of acquisition. Management utilizes various valuation techniques including discounted cash flow analyses to determine these fair values. Any excess of the purchase price over amounts allocated to the acquired assets, including identifiable intangible assets, and liabilities assumed is recorded as goodwill.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill resulted from the acquisition of Tri-Valley Bank (“Tri-Valley”) on April 6, 2018 and United American Bank (“United American”) on May 4, 2018, and from acquisitions in prior years. Goodwill represents the excess of the purchase price over the fair value of acquired tangible assets and liabilities and identifiable intangible assets. Goodwill is assessed at least annually for impairment and any such impairment is recognized in the period identified. Other intangible assets consist of core deposit intangible assets and a below market value lease intangible asset, arising from the United American and Tri-Valley acquisitions. They are initially measured at fair value and then are amortized over their estimated useful lives. The core deposits intangible assets from the acquisitions of United American and Tri-Valley are being amortized on an accelerated method over ten years. The below market value lease intangible assets are being amortized on the straight line method over three years for United American and eleven years for Tri-Valley.
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 May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers”, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The standard replaces most existing revenue recognition guidance in GAAP. The new standard was effective for the Company on January 1, 2018. Adoption of the standard did not have a material impact on the Company’s consolidated financial statements and related disclosures as the Company’s primary sources of revenues are derived from interest and dividends earned on loans, investment securities, and other financial instruments that are not within the scope of the standard. The Company’s revenue recognition pattern for revenue streams within the scope of the standard, including but not limited to service charges on deposit accounts and gains/losses on the sale of other real estate owned (“OREO”), did not change significantly from current practice. The standard permits the use of either the full retrospective or modified retrospective transition method. The Company elected to use the modified retrospective transition method which requires application of the standard to uncompleted contracts at the date of adoption however, periods prior to the date of adoption were not retrospectively revised as the impact of the standard on uncompleted contracts at the date of adoption was not material. See Note 15 – Revenue Recognition for more information. In January 2016, the FASB issued ASU No. 2016-01, “Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities.” The guidance affects the accounting for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements of financial instruments. The standard was effective for the Company on January 1, 2018 and resulted in the use of an exit price rather than an entrance price to determine the fair value of financial instruments not measured at fair value on a non-recurring basis in the consolidated balance sheets. See Note 10 – Fair Value regarding the valuation of the loan portfolio. In March 2017, the FASB issued ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The standard amended existing guidance to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost. The amendments require that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit costs are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. The amendments allow only the service cost component to be eligible for capitalization. The Company adopted the new guidance on January 1, 2018, and there was no material impact to the financial statements. Newly Issued, but not yet Effective Accounting Standards 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 provisions of this ASU and have determined that the provisions of ASU No. 2016-02 will result in an increase in assets to recognize the present value of the lease obligations with a corresponding increase in liabilities; however, we do not expect this to have a material impact to the Company’s results of operations or cash flows. 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 debt securities. The update amends the accounting for credit losses on available for sale securities, 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 have formed a committee that is assessing our data and system needs and are evaluating the impact of adopting the new guidance. The committee has also selected a vendor to assist in generating loan level cash flows and disclosures. We expect to recognize a one-time cumulative effect adjustment to the allowance for loan losses as of the beginning of the first reporting period in which the new standard is effective, but cannot yet determine the magnitude of any such one-time adjustment or the overall impact of the new guidance on the consolidated financial statements. In January 2017, the FASB issued accounting standards ASU No. 2017-04, Simplifying the Test for Goodwill Impairment. The provisions of the update eliminate the existing second step of the goodwill impairment test which provides for the allocation of reporting unit fair value among existing assets and liabilities, with the net remaining amount representing the implied fair value of goodwill. In replacement of the existing goodwill impairment rule, the update will provide that impairment should be recognized as the excess of any of the reporting unit’s goodwill over the fair value of the reporting unit. Under the provisions of this update, the amount of the impairment is limited to the carrying value of the reporting unit’s goodwill. For public business entities that are SEC filers, the amendments of the update will become effective in fiscal years beginning after December 15, 2019. Management does not expect the requirements of this update to have a material impact on the Company’s financial position, results of operations or cash flows.