Accounting Standards Updates (Policies)	6 Months Ended
Jun. 30, 2017
Accounting Policies [Abstract]
Accounting Standards Updates	Accounting Standards Updates ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 implements a common revenue standard that clarifies the principles for recognizing revenue. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve that core principle, an entity should apply the following steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) the entity satisfies a performance obligation. ASU 2014-09 was originally going to be effective for us on January 1, 2017; however, the FASB recently issued ASU 2015-14, “Revenue from Contracts with Customers (Topic 606) - Deferral of the Effective Date" which deferred the effective date of ASU 2014-09 by one year to January 1, 2018. Tompkins’ revenue is comprised of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and non-interest income. With respect to noninterest income, the Company has identified revenue streams within the scope of the guidance, and is performing an evaluation of the underlying revenue contracts. Tompkins does not expect these changes to have a significant impact on the Company’s consolidated financial statements. The Company expects to adopt the standard in the first quarter of 2018 with a cumulative effect adjustment to opening retained earnings, if such adjustment is deemed to be significant. ASU 2016-01, “Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-1, among other things, (i) requires equity investments, with certain exceptions, to be measured at fair value with changes in fair value recognized in net income, (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iii) 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, (iv) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes, (v) requires an entity to present separately in other comprehensive income the portion of the total change in the 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, (vi) 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 (viii) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale. ASU 2016-1 will be effective for us on January 1, 2018 and is not expected to have a significant impact on our consolidated financial statements. ASU 2016-02,“Leases (Topic 842).” ASU 2016-02 will, among other things, require lessees to recognize a lease liability, which is a lessee‘s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. ASU 2016-02 does not significantly change lease accounting requirements applicable to lessors; however, certain changes were made to align, where necessary, lessor accounting with the lessee accounting model and ASC Topic 606, “Revenue from Contracts with Customers.” ASU 2016-2 will be effective for Tompkins on January 1, 2019 and will require transition using a modified retrospective approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The Company occupies certain banking offices and uses certain equipment under noncancelable operating lease agreements, which currently are not reflected in its consolidated statement of condition. Upon adoption of the guidance, the Company expects to report increased assets and increased liabilities as a result of recognizing right-of-use assets and lease liabilities on its consolidated statement of condition. Tompkins is currently evaluating the extent of the impact that the adoption of this ASU will have on our consolidated financial statements. ASU 2016-05“Derivatives and Hedging (Topic 815) Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships.” ASU 2016-05 clarifies that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument under ASC Topic 815 does not, in and of itself, require dedesignation of that hedging relationship provided that all other hedge accounting criteria continue to be met. ASU 2016-05 became effective for Tompkins on January 1, 2017 and did not have a significant impact on our consolidated financial statements. ASU 2016-07, “Investments - Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to the Equity Method of Accounting.” The amendments affect all entities that have an investment that becomes qualified for the equity method of accounting as a result of an increase in the level of ownership interest or degree of influence. ASU 2016-07 simplifies the transition to the equity method of accounting by eliminating retroactive adjustment of the investment when an investment qualifies for use of the equity method, among other things. ASU 2016-07 became effective for Tompkins on January 1, 2017 and did not have a significant impact on our consolidated financial statements. ASU 2016-08, “Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net).” ASU 2016-08 was issued to clarify certain principal versus agent considerations within the implementation guidance of ASC Topic 606, “Revenue from Contracts with Customers.” The effective date and transition of ASU 2016-08 is the same as the effective date and transition of ASU 2014-09, "Revenue from Contracts with Customers (Topic 606)," as discussed above. Tompkins is currently evaluating the potential impact of ASU 2016-08 on our consolidated financial statements. ASU No. 2016-10, “Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing.” ASU 2016-10 was issued to clarify ASC Topic 606, “Revenue from Contracts with Customers” related to (i) identifying performance obligations; and (ii) the licensing implementation guidance. The effective date and transition of ASU 2016-10 is the same as the effective date and transition of ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” as discussed above. Tompkins is currently evaluating the potential impact of ASU 2016-10 on our consolidated financial statements. ASU No. 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” ASU 2016-13 requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts and requires enhanced disclosures related to the significant estimates and judgments used in estimating credit losses, as well as the credit quality and underwriting standards of an organization’s portfolio. In addition, ASU 2016-13 amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. ASU 2016-13 will be effective on January 1, 2020. Tompkins is currently evaluating the requirements of the new guidance to determine what modifications to our existing allowance methodology may be required. The Company expects that the new guidance will likely result in an increase in the allowance; however, Tompkins is unable to quantify the impact at this time since we are still reviewing the guidance. The extent of any impact to our allowance will depend, in part, upon the composition of our loan portfolio at the adoption date as well as economic conditions and loss forecasts at that date. ASU 2016-15, “Statement of Cash Flows (Topic 230) - Classification of Certain Cash Receipts and Cash Payments.” ASU 2016-15 provides guidance related to certain cash flow issues in order to reduce the current and potential future diversity in practice. ASU 2016-15 will be effective for us on January 1, 2018. Tompkins is currently evaluating the potential impact of ASU 2016-15 but does not expect it to have a significant impact on our consolidated financial statements. ASU 2017-04, “Intangibles - Goodwill and Other (Topic 350) - Simplifying the Test for Goodwill Impairment.” ASU 2017-04 eliminates Step 2 from the goodwill impairment test which required entities to compute the implied fair value of goodwill. Under ASU 2017-04, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. ASU 2017-04 will be effective for us on January 1, 2020, with early adoption permitted for interim or annual impairment tests beginning in 2017. Tompkins is currently evaluating the potential impact of ASU 2017-04 on our consolidated financial statements. ASU 2017-05, “Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20) - Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets.” ASU 2017-05 clarifies the scope of Subtopic 610-20 and adds guidance for partial sales of nonfinancial assets, including partial sales of real estate. Historically, U.S. GAAP contained several different accounting models to evaluate whether the transfer of certain assets qualified for sale treatment. ASU 2017-05 reduces the number of potential accounting models that might apply and clarifies which model does apply in various circumstances. ASU 2017-05 will be effective for us on January 1, 2018. Tompkins is currently evaluating the potential impact of ASU 2017-05 on our consolidated financial statements. ASU 2017-07, “Compensation-Retirement Benefits (Topic 715 - Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.”), which requires that the service cost component of the Company's net periodic pension cost and net periodic postretirement benefit cost be included in the same line item as other compensation costs arising from services rendered by employees, with the other components of net periodic benefit cost being classified outside of a subtotal of income from operations. Of the components of net periodic benefit cost, only the service cost component will be eligible for asset capitalization. ASU 2017-07 is effective for the Company beginning January 1, 2018 and is required to be applied retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement. Tompkins is currently evaluating the potential impact of ASU 2017-07 on our consolidated financial statements. ASU 2017-08 “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20) - Premium Amortization on Purchased Callable Debt Securities.” ASU 2017-08 shortens the amortization period for certain callable debt securities held at a premium to require such premiums to be amortized to the earliest call date unless applicable guidance related to certain pools of securities is applied to consider estimated prepayments. Under prior guidance, entities were generally required to amortize premiums on individual, non-pooled callable debt securities as a yield adjustment over the contractual life of the security. ASU 2017-08 does not change the accounting for callable debt securities held at a discount. ASU 2017-08 will be effective for us on January 1, 2019, with early adoption permitted. Tompkins is currently evaluating the potential impact of ASU 2017-08 on our consolidated financial statements. ASU 2017-09, “Compensation-Stock Compensation (Topic 718)- Scope of Modification Accounting.” ASU 2017-09 clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. Under ASU 2017-09, an entity will not apply modification accounting to a share-based payment award if all of the following are the same immediately before and after the change: (i) the award's fair value, (ii) the award's vesting conditions and (iii) the award's classification as an equity or liability instrument. ASU 2017-09 will be effective for us on January 1, 2018 and is not expected to have a significant impact on our consolidated financial statements.

Accounting Standards Updates

ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 implements a common revenue standard that clarifies the principles for recognizing revenue. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve that core principle, an entity should apply the following steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) the entity satisfies a performance obligation. ASU 2014-09 was originally going to be effective for us on January 1, 2017; however, the FASB recently issued ASU 2015-14, “Revenue from Contracts with Customers (Topic 606) - Deferral of the Effective Date" which deferred the effective date of ASU 2014-09 by one year to January 1, 2018. Tompkins’ revenue is comprised of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and non-interest income. With respect to noninterest income, the Company has identified revenue streams within the scope of the guidance, and is performing an evaluation of the underlying revenue contracts. Tompkins does not expect these changes to have a significant impact on the Company’s consolidated financial statements. The Company expects to adopt the standard in the first quarter of 2018 with a cumulative effect adjustment to opening retained earnings, if such adjustment is deemed to be significant.

ASU 2016-01, “Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-1, among other things, (i) requires equity investments, with certain exceptions, to be measured at fair value with changes in fair value recognized in net income, (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iii) 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, (iv) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes, (v) requires an entity to present separately in other comprehensive income the portion of the total change in the 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, (vi) 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 (viii) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale. ASU 2016-1 will be effective for us on January 1, 2018 and is not expected to have a significant impact on our consolidated financial statements.

ASU 2016-02,“Leases (Topic 842).” ASU 2016-02 will, among other things, require lessees to recognize a lease liability, which is a lessee‘s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. ASU 2016-02 does not significantly change lease accounting requirements applicable to lessors; however, certain changes were made to align, where necessary, lessor accounting with the lessee accounting model and ASC Topic 606, “Revenue from Contracts with Customers.” ASU 2016-2 will be effective for Tompkins on January 1, 2019 and will require transition using a modified retrospective approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The Company occupies certain banking offices and uses certain equipment under noncancelable operating lease agreements, which currently are not reflected in its consolidated statement of condition. Upon adoption of the guidance, the Company expects to report increased assets and increased liabilities as a result of recognizing right-of-use assets and lease liabilities on its consolidated statement of condition. Tompkins is currently evaluating the extent of the impact that the adoption of this ASU will have on our consolidated financial statements.

ASU 2016-05“Derivatives and Hedging (Topic 815) Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships.” ASU 2016-05 clarifies that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument under ASC Topic 815 does not, in and of itself, require dedesignation of that hedging relationship provided that all other hedge accounting criteria continue to be met. ASU 2016-05 became effective for Tompkins on January 1, 2017 and did not have a significant impact on our consolidated financial statements.

ASU 2016-07, “Investments - Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to the Equity Method of Accounting.” The amendments affect all entities that have an investment that becomes qualified for the equity method of accounting as a result of an increase in the level of ownership interest or degree of influence. ASU 2016-07 simplifies the transition to the equity method of accounting by eliminating retroactive adjustment of the investment when an investment qualifies for use of the equity method, among other things. ASU 2016-07 became effective for Tompkins on January 1, 2017 and did not have a significant impact on our consolidated financial statements.

ASU 2016-08, “Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net).” ASU 2016-08 was issued to clarify certain principal versus agent considerations within the implementation guidance of ASC Topic 606, “Revenue from Contracts with Customers.” The effective date and transition of ASU 2016-08 is the same as the effective date and transition of ASU 2014-09, "Revenue from Contracts with Customers (Topic 606)," as discussed above. Tompkins is currently evaluating the potential impact of ASU 2016-08 on our consolidated financial statements.

ASU No. 2016-10, “Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing.” ASU 2016-10 was issued to clarify ASC Topic 606, “Revenue from Contracts with Customers” related to (i) identifying performance obligations; and (ii) the licensing implementation guidance. The effective date and transition of ASU 2016-10 is the same as the effective date and transition of ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” as discussed above. Tompkins is currently evaluating the potential impact of ASU 2016-10 on our consolidated financial statements.

ASU No. 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” ASU 2016-13 requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts and requires enhanced disclosures related to the significant estimates and judgments used in estimating credit losses, as well as the credit quality and underwriting standards of an organization’s portfolio. In addition, ASU 2016-13 amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. ASU 2016-13 will be effective on January 1, 2020. Tompkins is currently evaluating the requirements of the new guidance to determine what modifications to our existing allowance methodology may be required. The Company expects that the new guidance will likely result in an increase in the allowance; however, Tompkins is unable to quantify the impact at this time since we are still reviewing the guidance. The extent of any impact to our allowance will depend, in part, upon the composition of our loan portfolio at the adoption date as well as economic conditions and loss forecasts at that date.

ASU 2016-15, “Statement of Cash Flows (Topic 230) - Classification of Certain Cash Receipts and Cash Payments.” ASU 2016-15 provides guidance related to certain cash flow issues in order to reduce the current and potential future diversity in practice. ASU 2016-15 will be effective for us on January 1, 2018. Tompkins is currently evaluating the potential impact of ASU 2016-15 but does not expect it to have a significant impact on our consolidated financial statements.

ASU 2017-04, “Intangibles - Goodwill and Other (Topic 350) - Simplifying the Test for Goodwill Impairment.” ASU 2017-04 eliminates Step 2 from the goodwill impairment test which required entities to compute the implied fair value of goodwill. Under ASU 2017-04, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. ASU 2017-04 will be effective for us on January 1, 2020, with early adoption permitted for interim or annual impairment tests beginning in 2017. Tompkins is currently evaluating the potential impact of ASU 2017-04 on our consolidated financial statements.

ASU 2017-05, “Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20) - Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets.” ASU 2017-05 clarifies the scope of Subtopic 610-20 and adds guidance for partial sales of nonfinancial assets, including partial sales of real estate. Historically, U.S. GAAP contained several different accounting models to evaluate whether the transfer of certain assets qualified for sale treatment. ASU 2017-05 reduces the number of potential accounting models that might apply and clarifies which model does apply in various circumstances. ASU 2017-05 will be effective for us on January 1, 2018. Tompkins is currently evaluating the potential impact of ASU 2017-05 on our consolidated financial statements.

ASU 2017-07, “Compensation-Retirement Benefits (Topic 715 - Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.”), which requires that the service cost component of the Company's net periodic pension cost and net periodic postretirement benefit cost be included in the same line item as other compensation costs arising from services rendered by employees, with the other components of net periodic benefit cost being classified outside of a subtotal of income from operations. Of the components of net periodic benefit cost, only the service cost component will be eligible for asset capitalization. ASU 2017-07 is effective for the Company beginning January 1, 2018 and is required to be applied retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement. Tompkins is currently evaluating the potential impact of ASU 2017-07 on our consolidated financial statements.

ASU 2017-08 “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20) - Premium Amortization on Purchased Callable Debt Securities.” ASU 2017-08 shortens the amortization period for certain callable debt securities held at a premium to require such premiums to be amortized to the earliest call date unless applicable guidance related to certain pools of securities is applied to consider estimated prepayments. Under prior guidance, entities were generally required to amortize premiums on individual, non-pooled callable debt securities as a yield adjustment over the contractual life of the security. ASU 2017-08 does not change the accounting for callable debt securities held at a discount. ASU 2017-08 will be effective for us on January 1, 2019, with early adoption permitted. Tompkins is currently evaluating the potential impact of ASU 2017-08 on our consolidated financial statements.

ASU 2017-09, “Compensation-Stock Compensation (Topic 718)- Scope of Modification Accounting.” ASU 2017-09 clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. Under ASU 2017-09, an entity will not apply modification accounting to a share-based payment award if all of the following are the same immediately before and after the change: (i) the award's fair value, (ii) the award's vesting conditions and (iii) the award's classification as an equity or liability instrument. ASU 2017-09 will be effective for us on January 1, 2018 and is not expected to have a significant impact on our consolidated financial statements.