Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2016
Accounting Policies [Abstract]
Consolidation Policy	The accompanying unaudited consolidated financial statements include 1^ST Constitution Bancorp (the “Company”), its wholly-owned subsidiary, 1^ST Constitution Bank (the “Bank”), and the Bank’s wholly-owned subsidiaries, 1^ST Constitution Investment Company of New Jersey, Inc., FCB Assets Holdings, Inc., 204 South Newman Street Corp., and 249 New York Avenue, LLC. 1st Constitution Capital Trust II, a subsidiary of the Company, is not included in the Company’s consolidated financial statements, as it is a variable interest entity and the Company is not the primary beneficiary. All significant intercompany accounts and transactions have been eliminated in consolidation and certain prior period amounts have been reclassified to conform to current year presentation. The accounting and reporting policies of the Company and its subsidiaries conform to accounting principles generally accepted in the United States of America (“U.S. GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”), including the instructions to Form 10-Q and Article 8 of Regulation S-X. Certain information and footnote disclosures normally included in financial statements have been condensed or omitted pursuant to such rules and regulations. These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto included in the Company’s Form 10-K for the year ended December 31, 2015, filed with the SEC on March 22, 2016.
Subsequent Events	The Company has evaluated events and transactions occurring subsequent to the balance sheet date of June 30, 2016 for items that should potentially be recognized or disclosed in these financial statements. The evaluation was conducted through the date these financial statements were issued.
Recent Accounting Pronouncements	Recent Accounting Pronouncements ASU Update 2016-13 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. In June 2016, the FASB issued ASU 2016-13 "Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments" which requires credit losses on most financial assets measured at amortized cost and certain other instruments to be measured using an expected credit loss model (referred to as the current expected credit loss (CECL) model). Under this model, entities will estimate credit losses over the entire contractual term of the instrument (considering estimated prepayments, but not expected extensions or modifications unless reasonable expectation of a troubled debt restructuring exists) from the date of initial recognition of that instrument. The ASU also replaces the current accounting model for purchased credit impaired loans and debt securities. The allowance for credit losses for purchased financial assets with a more-than-insignificant amount of credit deterioration since origination ("PCD assets") should be determined in a similar manner to other financial assets measured on an amortized cost basis. Upon initial recognition, the allowance for credit losses is added to the purchase price ("gross up approach") to determine the initial amortized cost basis. The subsequent accounting for PCD financial assets will use the CECL model described above. The ASU made certain targeted amendments to the existing impairment model for available-for-sale (AFS) debt securities. For an AFS debt security for which there is neither the intent nor a more-likely-than-not requirement to sell, an entity will record credit losses as an allowance rather than a write-down of the amortized cost basis. For public business entities that are SEC filers, the amendments are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for all entities as of the fiscal year beginning after December 15, 2018, including interim periods within those fiscal years. The Company is currently evaluating the impact of the pending adoption of the new standard on its consolidated financial statements. ASU Update 2016-09 Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. In March 2016, the FASB issued ASU 2016-09 "Compensation-Stock Compensation: Improvements to Employee Share-Based Payment Accounting" to simplify the accounting for stock compensation. The ASU focuses on income tax accounting, award classification, estimating forfeitures and cash flow presentation. The ASU also provides certain accounting policy alternatives to nonpublic entities. The ASU simplifies several aspects of the stock compensation guidance in Topic 718 and other related guidance. The following six amendments apply to all entities: (1) accounting for income taxes upon vesting or exercise of share-based payments and related EPS effects, (2) classification of excess tax benefits on the statement of cash flows, (3) accounting for forfeitures, (4) liability classification exception for statutory tax withholding requirements, (5) cash flow presentation of employee taxes paid when an employer withholds shares for tax-withholding purposes and (6) elimination of the indefinite deferral in Topic 718. For public business entities, the amendments are effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. For all other entities, the amendments are effective for annual periods beginning after December 15, 2017, and interim periods within annual periods beginning after December 15, 2018. Early adoption is permitted for any entity in any interim or annual period for which the financial statements have not been issued or made available to be issued. If an entity early adopts the amendments in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. An entity that elects early adoption must adopt all of the amendments in the same period. The Company is currently evaluating the impact of the pending adoption of the new standard on its consolidated financial statements. ASU Update 2016-02: Leases. In February 2016, the FASB issued ASU 2016-02 "Leases." From the lessee's perspective, the new standard establishes a right- of-use ("ROU") model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement for a lessee. From the lessor's perspective, the new standard requires a lessor to classify leases as either sales-type, finance or operating. A lease will be treated as a sale if it transfers all of the risks and rewards, as well as control of the underlying asset, to the lessee. If risks and rewards are conveyed without the transfer of control, the lease is treated as a financing. If the lessor doesn’t convey risks and rewards or control, an operating lease results. The new standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. A modified retrospective transition approach is required for lessors for sales-type, direct financing, and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. The Company is currently evaluating the impact of the pending adoption of the new standard on its consolidated financial statements. ASU Update 2016-01 Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities. In January 2016, the FASB issued ASU 2016-01 "Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities." The guidance in the ASU, among other things, requires equity investments, with certain exceptions, to be measured at fair value with changes in fair value recognized in net income; simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; eliminates the requirement for public business entities to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; requires an entity to present separately in other comprehensive income the portion of the change in fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments; requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements; and clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities. The guidance in this ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company does not expect the adoption of this guidance to have a material impact on the Company's consolidated financial statements. ASU Update 2015-16 Business Combination (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments. In September 2015, the FASB issued ASU 2015-16 "Business Combination (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments," to require adjustments to provisional amounts that are identified during the measurement period to be recognized in the reporting period in which the adjustment amounts are determined. This includes any effect on earnings of changes in depreciation, amortization or other income effects 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 would require an entity to disclose (either on the face of the income statement or in the notes) the nature and amount of measurement-period adjustments recognized in the current period, including separately the amounts in current-period income statement line items 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 are effective for public business entities for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015 and for all other entities for fiscal years beginning after December 31, 2016 and for interim periods within fiscal years beginning after December 15, 2017. Adoption of this guidance in 2016 did not have a material impact on the Company’s consolidated financial statements. ASU 2014-9 Revenue from Contracts with Customers (Topic 606) In May 2014, the FASB issued ASU 2014-9, “Revenue from Contracts with Customers (Topic 606).” The objective of this amendment is to clarify the principles for recognizing revenue and to develop a common revenue standard for U.S. GAAP. This update affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets unless those contracts are in the scope of other standards. This ASU, which does not apply to financial instruments, is effective for interim and annual reporting periods beginning after December 15, 2017. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim periods within that year. The Company does not expect the adoption of this guidance to have a material impact on the Company's consolidated financial statements related to this guidance. ASU 2014-12 Accounting for Share-Based-Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved After the Requisite Service Period (a consensus of the FAS Emerging Issues Task Force). In June 2014, the FASB issued ASU 2014-12, "Accounting for Share-Based-Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved After the Requisite Service Period," which requires that a performance target included in a share-based payment award that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. This update is effective for interim and annual periods beginning after December 15, 2015. The amendments can be applied prospectively to all awards granted or modified after the effective date or retrospectively to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented and to all new or modified awards thereafter. Adoption of this guidance in 2016 did not have a material impact on the Company’s consolidated financial statements.

Recent Accounting Pronouncements

ASU Update 2016-13 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.

In June 2016, the FASB issued ASU 2016-13 "Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments" which requires credit losses on most financial assets measured at amortized cost and certain other instruments to be measured using an expected credit loss model (referred to as the current expected credit loss (CECL) model). Under this model, entities will estimate credit losses over the entire contractual term of the instrument (considering estimated prepayments, but not expected extensions or modifications unless reasonable expectation of a troubled debt restructuring exists) from the date of initial recognition of that instrument.

The ASU also replaces the current accounting model for purchased credit impaired loans and debt securities. The allowance for credit losses for purchased financial assets with a more-than-insignificant amount of credit deterioration since origination ("PCD assets") should be determined in a similar manner to other financial assets measured on an amortized cost basis. Upon initial recognition, the allowance for credit losses is added to the purchase price ("gross up approach") to determine the initial amortized cost basis. The subsequent accounting for PCD financial assets will use the CECL model described above.

The ASU made certain targeted amendments to the existing impairment model for available-for-sale (AFS) debt securities. For an AFS debt security for which there is neither the intent nor a more-likely-than-not requirement to sell, an entity will record credit losses as an allowance rather than a write-down of the amortized cost basis.

For public business entities that are SEC filers, the amendments are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for all entities as of the fiscal year beginning after December 15, 2018, including interim periods within those fiscal years.

The Company is currently evaluating the impact of the pending adoption of the new standard on its consolidated financial statements.

ASU Update 2016-09 Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.

In March 2016, the FASB issued ASU 2016-09 "Compensation-Stock Compensation: Improvements to Employee Share-Based Payment Accounting" to simplify the accounting for stock compensation. The ASU focuses on income tax accounting, award classification, estimating forfeitures and cash flow presentation. The ASU also provides certain accounting policy alternatives to nonpublic entities. The ASU simplifies several aspects of the stock compensation guidance in Topic 718 and other related guidance. The following six amendments apply to all entities: (1) accounting for income taxes upon vesting or exercise of share-based payments and related EPS effects, (2) classification of excess tax benefits on the statement of cash flows, (3) accounting for forfeitures, (4) liability classification exception for statutory tax withholding requirements, (5) cash flow presentation of employee taxes paid when an employer withholds shares for tax-withholding purposes and (6) elimination of the indefinite deferral in Topic 718.

For public business entities, the amendments are effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. For all other entities, the amendments are effective for annual periods beginning after December 15, 2017, and interim periods within annual periods beginning after December 15, 2018. Early adoption is permitted for any entity in any interim or annual period for which the financial statements have not been issued or made available to be issued. If an entity early adopts the amendments in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. An entity that elects early adoption must adopt all of the amendments in the same period. The Company is currently evaluating the impact of the pending adoption of the new standard on its consolidated financial statements.

ASU Update 2016-02: Leases.

In February 2016, the FASB issued ASU 2016-02 "Leases." From the lessee's perspective, the new standard establishes a right- of-use ("ROU") model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement for a lessee. From the lessor's perspective, the new standard requires a lessor to classify leases as either sales-type, finance or operating. A lease will be treated as a sale if it transfers all of the risks and rewards, as well as control of the underlying asset, to the lessee. If risks and rewards are conveyed without the transfer of control, the lease is treated as a financing. If the lessor doesn’t convey risks and rewards or control, an operating lease results.

The new standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. A modified retrospective transition approach is required for lessors for sales-type, direct financing, and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. The Company is currently evaluating the impact of the pending adoption of the new standard on its consolidated financial statements.

ASU Update 2016-01 Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities.

In January 2016, the FASB issued ASU 2016-01 "Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities." The guidance in the ASU, among other things, requires equity investments, with certain exceptions, to be measured at fair value with changes in fair value recognized in net income; simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; eliminates the requirement for public business entities to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; requires an entity to present separately in other comprehensive income the portion of the change in fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments; requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements; and clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities. The guidance in this ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company does not expect the adoption of this guidance to have a material impact on the Company's consolidated financial statements.

ASU Update 2015-16 Business Combination (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments.

In September 2015, the FASB issued ASU 2015-16 "Business Combination (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments," to require adjustments to provisional amounts that are identified during the measurement period to be recognized in the reporting period in which the adjustment amounts are determined. This includes any effect on earnings of changes in depreciation, amortization or other income effects 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 would require an entity to disclose (either on the face of the income statement or in the notes) the nature and amount of measurement-period adjustments recognized in the current period, including separately the amounts in current-period income statement line items 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 are effective for public business entities for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015 and for all other entities for fiscal years beginning after December 31, 2016 and for interim periods within fiscal years beginning after December 15, 2017. Adoption of this guidance in 2016 did not have a material impact on the Company’s consolidated financial statements.

ASU 2014-9 Revenue from Contracts with Customers (Topic 606)

In May 2014, the FASB issued ASU 2014-9, “Revenue from Contracts with Customers (Topic 606).” The objective of this amendment is to clarify the principles for recognizing revenue and to develop a common revenue standard for U.S. GAAP. This update affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets unless those contracts are in the scope of other standards. This ASU, which does not apply to financial instruments, is effective for interim and annual reporting periods beginning after December 15, 2017. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim periods within that year. The Company does not expect the adoption of this guidance to have a material impact on the Company's consolidated financial statements related to this guidance.

ASU 2014-12 Accounting for Share-Based-Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved After the Requisite Service Period (a consensus of the FAS Emerging Issues Task Force).

In June 2014, the FASB issued ASU 2014-12, "Accounting for Share-Based-Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved After the Requisite Service Period," which requires that a performance target included in a share-based payment award that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. This update is effective for interim and annual periods beginning after December 15, 2015. The amendments can be applied prospectively to all awards granted or modified after the effective date or retrospectively to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented and to all new or modified awards thereafter. Adoption of this guidance in 2016 did not have a material impact on the Company’s consolidated financial statements.