Accounting Policies Recently Adopted and Pending Accounting Pronouncements (Policies)	3 Months Ended
Mar. 31, 2017
Accounting Policies [Abstract]
Accounting Policies Recently Adopted and Pending Accounting Pronouncements	ASU 2017-08, “Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.” Issued in March 2017, ASU 2017-08 amends the amortization period for certain purchased callable debt securities held at a premium. In particular, the amendments in ASU 2017-08 require the premium to be amortized to the earliest call date. The amendments do not, however, require an accounting change for securities held at a discount; instead, the discount continues to be amortized to maturity. Notably, the amendments in this ASU more closely align the amortization period of premiums and discounts to expectations incorporated in market pricing on the underlying securities. Securities within the scope of ASU 2017-08 are purchased debt securities that have explicit, noncontingent call features that are callable at fixed prices and on preset dates. The amendments of ASU 2017-08 become effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018. As of March 31, 2017, Trustmark’s total unamortized premium for purchased debt securities within the scope of ASU 2017-08 was immaterial. Management will continue to evaluate the impact this ASU will have on Trustmark’s consolidated financial statements through its effective date; however, the adoption of ASU 2017-08 is not expected to have a material impact Trustmark’s 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.” Issued in March 2017, ASU 2017-07 is designed to improve guidance related to the presentation of defined benefit costs in the income statement. In particular, ASU No. 2017-07 requires that an employer report the service cost component in the same line item(s) as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost 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. If a separate line item or items are used to present the other components of net benefit cost, then that line item or items must be appropriately described. However, if a separate line item or items are not used, then the line item(s) used in the income statement to present the other components of net benefit cost must be disclosed. Additionally, ASU 2017-07 allows only the service cost component to be eligible for capitalization, when applicable. The amendments of ASU 2017-07 become effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Management is currently evaluating the impact this ASU will have on Trustmark’s consolidated financial statements; however, the adoption of ASU 2017-07 is not expected to have a material impact Trustmark’s consolidated financial statements. ASU 2017-04, “Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” Issued in January 2017, ASU 2017-04 simplifies the manner in which an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit's goodwill with the carrying amount of that goodwill. In computing the implied fair value of goodwill under Step 2, an entity, prior to the amendments in ASU 2017-04, had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities, including unrecognized assets and liabilities, in accordance with the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. However, under the amendments in ASU 2017-04, an entity should (1) perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, and (2) recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value, with the understanding that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, ASU 2017-04 removes the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails such qualitative test, to perform Step 2 of the goodwill impairment test. ASU 2017-04 is effective prospectively for annual, or any interim, goodwill impairment tests in fiscal years beginning after December 15, 2019. Based on Trustmark’s annual goodwill impairment test performed as of October 1, 2016, the fair value of its reporting units exceeded the carrying value and, therefore, the related goodwill was not impaired. Management will continue to evaluate the impact this ASU will have on Trustmark’s consolidated financial statements through its effective date; however, the adoption of ASU 2017-04 is not expected to have a material impact Trustmark’s consolidated financial statements. ASU 2017-01, “Business Combinations (Topic 805) - Clarifying the Definition of a Business.” Issued in January 2017, ASU 2017-01 clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses, which determines whether goodwill should be recorded or not. The amendments in ASU No. 2017-01 provide a screen to determine when a set of assets and activities (collectively, a “set”) is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. If, however, the screen is not met, then the amendments in ASU 07-01 require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and remove the evaluation of whether a market participant could replace missing elements. The revised definition will result in more transactions being recorded as asset acquisitions or dispositions as opposed to business acquisitions or dispositions. The amendments of ASU 2017-01 are effective for interim and annual periods beginning after December 15, 2017. Management is currently evaluating the impact this ASU will have on Trustmark’s consolidated financial statements; however, the adoption of ASU 2017-01 is not expected to have a material impact Trustmark’s consolidated financial statements. ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments.” Issued in August 2016, ASU 2016-15 provides guidance to reduce the diversity in practice of how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The amendments of ASU 2016-15 provide guidance on eight specific cash flow: (i) debt prepayment or debt extinguishment costs; (ii) settlement of zero-coupon bonds; (iii) contingent consideration payments made after a business combination; (iv) proceeds from the settlement of insurance claims; (v) proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; (vi) distributions received from equity method investees; (vii) beneficial interests in securitization transactions and (viii) separately identifiable cash flows and application of the predominance principle. The amendments of ASU 2016-15 are effective for interim and annual periods beginning after December 15, 2017. Trustmark plans to adopt the amendments of ASU 2016-15 during the first quarter of 2018. Management has evaluated the amendments of ASU 2016-15 and does not believe that adoption of this ASU will impact Trustmark’s existing presentation of the applicable cash receipts and cash payments on its consolidated statements of cash flows. ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” Issued in June 2016, ASU 2016-13 will add FASB ASC Topic 326, “Financial Instruments-Credit Losses” and finalizes amendments to FASB ASC Subtopic 825-15, “Financial Instruments-Credit Losses.” The amendments of ASU 2016-13 are intended to provide financial statement users with more decision-useful information related to expected credit losses on financial instruments and other commitments to extend credit by replacing the current incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. The amendments of ASU 2016-13 eliminate the probable initial recognition threshold and, in turn, reflect an entity’s current estimate of all expected credit losses. ASU 2016-13 does not specify the method for measuring expected credit losses, and an entity is allowed to apply methods that reasonably reflect its expectations of the credit loss estimate. Additionally, the amendments of ASU 2016-13 require that credit losses on available for sale debt securities be presented as an allowance rather than as a write-down. The amendments of ASU 2016-13 are effective for interim and annual periods beginning after December 15, 2019. Earlier application is permitted for interim and annual periods beginning after December 15, 2018. Trustmark plans to adopt the amendments of ASU 2016-13 during the first quarter of 2020. Trustmark has established a steering committee which includes the appropriate members of Management to evaluate the impact this ASU will have on Trustmark’s financial position, results of operations and financial statement disclosures and determine the most appropriate method of implementing the amendments in this ASU as well as any resources needed to implement the amendments. The steering committee is currently evaluating various third-party vendors to determine the most appropriate product for Trustmark and the level of assistance that will be required for implementation. ASU 2016-09, “Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.” Issued in March 2016, ASU 2016-09 seeks to reduce complexity in accounting standards by simplifying several aspects of the accounting for share-based payment transactions. The amendments of ASU 2016-09 include: (i) requiring all excess tax benefits and tax deficiencies to be recognized as income tax expense or benefit in the income statement; (ii) requiring excess tax benefits to be classified along with other income tax cash flows as an operating activity on the statement of cash flow; (iii) allowing an entity to make an entity-wide accounting policy election to either estimate the number of awards that expect to vest or account for forfeitures when they occur; (iv) change the threshold to qualify for equity classification to permit withholding up to the maximum statutory tax rates in the applicable jurisdictions; and (v) requiring that cash paid by an employer when directly withholding shares for tax-withholding purposes to be classified as a financing activity on the statement of cash flows. The amendments of ASU 2016-09 became effective for Trustmark on January 1, 2017 and did not have a material impact on Trustmark’s consolidated financial statements. Trustmark has made an entity-wide accounting policy election to account for forfeitures of stock awards as they occur. Changes as required by the amendments of ASU 2016-09 are presented in the accompanying consolidated statements of cash flows. ASU 2016-02, “Leases (Topic 842).” Issued in February 2016, ASU 2016-02 was issued by the FASB to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and by disclosing key information about leasing arrangements. 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, the ASU contains some targeted improvements that are intended to align, where necessary, lessor accounting with the lessee accounting model and with the updated revenue recognition guidance issued in 2014. The amendments of ASU 2016-02 are effective for interim and annual periods beginning after December 15, 2018. Trustmark plans to adopt the amendments of ASU 2016-02 beginning in the first quarter of 2019. At adoption, Trustmark will recognize a lease asset and a corresponding lease liability on its consolidated balance sheet for its total lease obligation measured on a discounted basis. As of December 31, 2016, all leases in which Trustmark was the lessee were classified as operating leases and the total outstanding lease obligation was $58.0 million, or 0.4% of total assets. Trustmark does not anticipant any material impact to its consolidated statements of income as a result of the adoption of this ASU. Trustmark has an immaterial amount of leases in which it is the lessor. Based on Management’s evaluation to date, Trustmark does not expect the amendments of ASU 2016-02 to have any material impact to these leases or the related income. Management will continue to evaluate the impact this ASU will have on Trustmark’s consolidated financial statements; however, the adoption of ASU 2016-02 is not expected to have a material impact on Trustmark’s consolidated financial statements. ASU 2016-01, “Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (An Amendment of the FASB Accounting Standards Codification).” Issued in January 2016, ASU 2016-01 is intended to enhance the reporting model for financial instruments to provide users of financial statements with improved decision-making information. The amendments of ASU 2016-01 include: (i) requiring equity investments, except those accounted for under the equity method of accounting or those that result in the consolidation of an investee, to be measured at fair value with changes in fair value recognized in net income; (ii) requiring a qualitative assessment to identify impairment of equity investments without readily determinable fair values; (iii) eliminating the requirement to disclose the method and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost on the balance sheet; (iv) requiring the use of the exit price notion when measuring the fair value of financial instruments for disclosure purposes; (v) requiring an entity that has elected the fair value option to measure the fair value of a liability to present separately in other comprehensive income the portion of the change in the fair value resulting from a change in the instrument-specific credit risk; (vi) requiring 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 (vii) clarifying that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity’s other deferred tax assets. The amendments of ASU 2016-01 are effective for interim and annual periods beginning after December 15, 2017. Trustmark plans to adopt the amendments of ASU 2016-01 during the first quarter of 2018. Management has evaluated the impact this ASU will have on Trustmark’s consolidated financial statements. Through this evaluation, Management has determined that the principal areas impacted by the amendments of ASU 2016-01 will be Trustmark’s investment in member bank stock, which are equity securities that do not have readily determinable fair values, and various fair value related disclosures. See Note 1 – Significant Accounting Policies, “Federal Home Loan Bank (FHLB) and Federal Reserve Bank of Atlanta Stock” included in Item 8 of Trustmark’s Annual Report on Form 10-K for information regarding Trustmark’s investment in member bank stock. The adoption of ASU 2016-01 is not expected to have a material impact on Trustmark’s consolidated financial statements. ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” Issued in May 2014, ASU 2014-09 will add FASB ASC Topic 606, “Revenue from Contracts with Customers,” and will supersede revenue recognition requirements in FASB ASC Topic 605, “Revenue Recognition,” as well as certain cost guidance in FASB ASC Topic 605-35, “Revenue Recognition – Construction-Type and Production-Type Contracts.” ASU 2014-09 provides a framework for revenue recognition that replaces the existing industry and transaction specific requirements under the existing standards. ASU 2014-09 requires an entity to apply a five-step model to determine when to recognize revenue and at what amount. The model specifies that revenue should be recognized when (or as) an entity transfers control of goods or services to a customer at the amount in which the entity expects to be entitled. Depending on whether certain criteria are met, revenue should be recognized either over time, in a manner that depicts the entity’s performance, or at a point in time, when control of the goods or services are transferred to the customer. ASU 2014-09 provides that an entity should apply the following steps: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. In addition, the existing requirements for the recognition of a gain or loss on the transfer of non-financial assets that are not in a contract with a customer are amended to be consistent with the guidance on recognition and measurement in ASU 2014-09. The amendments of ASU 2014-09 may be applied either retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application. If the transition method of application is elected, the entity should also provide the additional disclosures in reporting periods that include the date of initial application of (1) the amount by which each financial statement line item is affected in the current reporting period, as compared to the guidance that was in effect before the change, and (2) an explanation of the reasons for significant changes. ASU 2015-14, “Revenue from Contracts with Customers (Topic 606)-Deferral of the Effective Date,” issued in August 2015, defers the effective date of ASU 2014-09 by one year. ASU 2015-14 provides that the amendments of ASU 2014-09 become effective for interim and annual periods beginning after December 15, 2017. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. All subsequently issued ASUs which provide additional guidance and clarifications to various aspects of FASB ASC Topic 606 will become effective when the amendments of ASU 2014-09 become effective. Trustmark plans to adopt these amendments during the first quarter of 2018. Management is continuing to evaluate the impact ASU 2014-09 will have on Trustmark’s consolidated financial statements as well as the most appropriate transition method of application. Based on this evaluation to date, Management has determined that the majority of the revenues earned by Trustmark are not within the scope of ASU 2014-09. Management also believes that for most revenue streams within the scope of ASU 2014-09, the amendments will not change the timing of when the revenue is recognized. Management will continue to evaluate the impact the adoption of ASU 2014-09 will have on Trustmark’s consolidated financial statements, focusing on noninterest income sources within the scope of ASU 2014-09 as well as new disclosures required by these amendments; however, the adoption of ASU 2014-09 is not expected to have a material impact on Trustmark’s consolidated financial statements.

ASU 2017-08, “Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.” Issued in March 2017, ASU 2017-08 amends the amortization period for certain purchased callable debt securities held at a premium. In particular, the amendments in ASU 2017-08 require the premium to be amortized to the earliest call date. The amendments do not, however, require an accounting change for securities held at a discount; instead, the discount continues to be amortized to maturity. Notably, the amendments in this ASU more closely align the amortization period of premiums and discounts to expectations incorporated in market pricing on the underlying securities. Securities within the scope of ASU 2017-08 are purchased debt securities that have explicit, noncontingent call features that are callable at fixed prices and on preset dates. The amendments of ASU 2017-08 become effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018. As of March 31, 2017, Trustmark’s total unamortized premium for purchased debt securities within the scope of ASU 2017-08 was immaterial. Management will continue to evaluate the impact this ASU will have on Trustmark’s consolidated financial statements through its effective date; however, the adoption of ASU 2017-08 is not expected to have a material impact Trustmark’s 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.” Issued in March 2017, ASU 2017-07 is designed to improve guidance related to the presentation of defined benefit costs in the income statement. In particular, ASU No. 2017-07 requires that an employer report the service cost component in the same line item(s) as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost 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. If a separate line item or items are used to present the other components of net benefit cost, then that line item or items must be appropriately described. However, if a separate line item or items are not used, then the line item(s) used in the income statement to present the other components of net benefit cost must be disclosed. Additionally, ASU 2017-07 allows only the service cost component to be eligible for capitalization, when applicable. The amendments of ASU 2017-07 become effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Management is currently evaluating the impact this ASU will have on Trustmark’s consolidated financial statements; however, the adoption of ASU 2017-07 is not expected to have a material impact Trustmark’s consolidated financial statements.

ASU 2017-04, “Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” Issued in January 2017, ASU 2017-04 simplifies the manner in which an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit's goodwill with the carrying amount of that goodwill. In computing the implied fair value of goodwill under Step 2, an entity, prior to the amendments in ASU 2017-04, had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities, including unrecognized assets and liabilities, in accordance with the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. However, under the amendments in ASU 2017-04, an entity should (1) perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, and (2) recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value, with the understanding that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, ASU 2017-04 removes the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails such qualitative test, to perform Step 2 of the goodwill impairment test. ASU 2017-04 is effective prospectively for annual, or any interim, goodwill impairment tests in fiscal years beginning after December 15, 2019. Based on Trustmark’s annual goodwill impairment test performed as of October 1, 2016, the fair value of its reporting units exceeded the carrying value and, therefore, the related goodwill was not impaired. Management will continue to evaluate the impact this ASU will have on Trustmark’s consolidated financial statements through its effective date; however, the adoption of ASU 2017-04 is not expected to have a material impact Trustmark’s consolidated financial statements.

ASU 2017-01, “Business Combinations (Topic 805) - Clarifying the Definition of a Business.” Issued in January 2017, ASU 2017-01 clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses, which determines whether goodwill should be recorded or not. The amendments in ASU No. 2017-01 provide a screen to determine when a set of assets and activities (collectively, a “set”) is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. If, however, the screen is not met, then the amendments in ASU 07-01 require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and remove the evaluation of whether a market participant could replace missing elements. The revised definition will result in more transactions being recorded as asset acquisitions or dispositions as opposed to business acquisitions or dispositions. The amendments of ASU 2017-01 are effective for interim and annual periods beginning after December 15, 2017. Management is currently evaluating the impact this ASU will have on Trustmark’s consolidated financial statements; however, the adoption of ASU 2017-01 is not expected to have a material impact Trustmark’s consolidated financial statements.

ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments.” Issued in August 2016, ASU 2016-15 provides guidance to reduce the diversity in practice of how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The amendments of ASU 2016-15 provide guidance on eight specific cash flow: (i) debt prepayment or debt extinguishment costs; (ii) settlement of zero-coupon bonds; (iii) contingent consideration payments made after a business combination; (iv) proceeds from the settlement of insurance claims; (v) proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; (vi) distributions received from equity method investees; (vii) beneficial interests in securitization transactions and (viii) separately identifiable cash flows and application of the predominance principle. The amendments of ASU 2016-15 are effective for interim and annual periods beginning after December 15, 2017. Trustmark plans to adopt the amendments of ASU 2016-15 during the first quarter of 2018. Management has evaluated the amendments of ASU 2016-15 and does not believe that adoption of this ASU will impact Trustmark’s existing presentation of the applicable cash receipts and cash payments on its consolidated statements of cash flows.

ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” Issued in June 2016, ASU 2016-13 will add FASB ASC Topic 326, “Financial Instruments-Credit Losses” and finalizes amendments to FASB ASC Subtopic 825-15, “Financial Instruments-Credit Losses.” The amendments of ASU 2016-13 are intended to provide financial statement users with more decision-useful information related to expected credit losses on financial instruments and other commitments to extend credit by replacing the current incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. The amendments of ASU 2016-13 eliminate the probable initial recognition threshold and, in turn, reflect an entity’s current estimate of all expected credit losses. ASU 2016-13 does not specify the method for measuring expected credit losses, and an entity is allowed to apply methods that reasonably reflect its expectations of the credit loss estimate. Additionally, the amendments of ASU 2016-13 require that credit losses on available for sale debt securities be presented as an allowance rather than as a write-down. The amendments of ASU 2016-13 are effective for interim and annual periods beginning after December 15, 2019. Earlier application is permitted for interim and annual periods beginning after December 15, 2018. Trustmark plans to adopt the amendments of ASU 2016-13 during the first quarter of 2020. Trustmark has established a steering committee which includes the appropriate members of Management to evaluate the impact this ASU will have on Trustmark’s financial position, results of operations and financial statement disclosures and determine the most appropriate method of implementing the amendments in this ASU as well as any resources needed to implement the amendments. The steering committee is currently evaluating various third-party vendors to determine the most appropriate product for Trustmark and the level of assistance that will be required for implementation.

ASU 2016-09, “Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.” Issued in March 2016, ASU 2016-09 seeks to reduce complexity in accounting standards by simplifying several aspects of the accounting for share-based payment transactions. The amendments of ASU 2016-09 include: (i) requiring all excess tax benefits and tax deficiencies to be recognized as income tax expense or benefit in the income statement; (ii) requiring excess tax benefits to be classified along with other income tax cash flows as an operating activity on the statement of cash flow; (iii) allowing an entity to make an entity-wide accounting policy election to either estimate the number of awards that expect to vest or account for forfeitures when they occur; (iv) change the threshold to qualify for equity classification to permit withholding up to the maximum statutory tax rates in the applicable jurisdictions; and (v) requiring that cash paid by an employer when directly withholding shares for tax-withholding purposes to be classified as a financing activity on the statement of cash flows. The amendments of ASU 2016-09 became effective for Trustmark on January 1, 2017 and did not have a material impact on Trustmark’s consolidated financial statements. Trustmark has made an entity-wide accounting policy election to account for forfeitures of stock awards as they occur. Changes as required by the amendments of ASU 2016-09 are presented in the accompanying consolidated statements of cash flows.

ASU 2016-02, “Leases (Topic 842).” Issued in February 2016, ASU 2016-02 was issued by the FASB to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and by disclosing key information about leasing arrangements. 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, the ASU contains some targeted improvements that are intended to align, where necessary, lessor accounting with the lessee accounting model and with the updated revenue recognition guidance issued in 2014. The amendments of ASU 2016-02 are effective for interim and annual periods beginning after December 15, 2018. Trustmark plans to adopt the amendments of ASU 2016-02 beginning in the first quarter of 2019. At adoption, Trustmark will recognize a lease asset and a corresponding lease liability on its consolidated balance sheet for its total lease obligation measured on a discounted basis. As of December 31, 2016, all leases in which Trustmark was the lessee were classified as operating leases and the total outstanding lease obligation was $58.0 million, or 0.4% of total assets. Trustmark does not anticipant any material impact to its consolidated statements of income as a result of the adoption of this ASU. Trustmark has an immaterial amount of leases in which it is the lessor. Based on Management’s evaluation to date, Trustmark does not expect the amendments of ASU 2016-02 to have any material impact to these leases or the related income. Management will continue to evaluate the impact this ASU will have on Trustmark’s consolidated financial statements; however, the adoption of ASU 2016-02 is not expected to have a material impact on Trustmark’s consolidated financial statements.

ASU 2016-01, “Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (An Amendment of the FASB Accounting Standards Codification).” Issued in January 2016, ASU 2016-01 is intended to enhance the reporting model for financial instruments to provide users of financial statements with improved decision-making information. The amendments of ASU 2016-01 include: (i) requiring equity investments, except those accounted for under the equity method of accounting or those that result in the consolidation of an investee, to be measured at fair value with changes in fair value recognized in net income; (ii) requiring a qualitative assessment to identify impairment of equity investments without readily determinable fair values; (iii) eliminating the requirement to disclose the method and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost on the balance sheet; (iv) requiring the use of the exit price notion when measuring the fair value of financial instruments for disclosure purposes; (v) requiring an entity that has elected the fair value option to measure the fair value of a liability to present separately in other comprehensive income the portion of the change in the fair value resulting from a change in the instrument-specific credit risk; (vi) requiring 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 (vii) clarifying that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity’s other deferred tax assets. The amendments of ASU 2016-01 are effective for interim and annual periods beginning after December 15, 2017. Trustmark plans to adopt the amendments of ASU 2016-01 during the first quarter of 2018. Management has evaluated the impact this ASU will have on Trustmark’s consolidated financial statements. Through this evaluation, Management has determined that the principal areas impacted by the amendments of ASU 2016-01 will be Trustmark’s investment in member bank stock, which are equity securities that do not have readily determinable fair values, and various fair value related disclosures. See Note 1 – Significant Accounting Policies, “Federal Home Loan Bank (FHLB) and Federal Reserve Bank of Atlanta Stock” included in Item 8 of Trustmark’s Annual Report on Form 10-K for information regarding Trustmark’s investment in member bank stock. The adoption of ASU 2016-01 is not expected to have a material impact on Trustmark’s consolidated financial statements.

ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” Issued in May 2014, ASU 2014-09 will add FASB ASC Topic 606, “Revenue from Contracts with Customers,” and will supersede revenue recognition requirements in FASB ASC Topic 605, “Revenue Recognition,” as well as certain cost guidance in FASB ASC Topic 605-35, “Revenue Recognition – Construction-Type and Production-Type Contracts.” ASU 2014-09 provides a framework for revenue recognition that replaces the existing industry and transaction specific requirements under the existing standards. ASU 2014-09 requires an entity to apply a five-step model to determine when to recognize revenue and at what amount. The model specifies that revenue should be recognized when (or as) an entity transfers control of goods or services to a customer at the amount in which the entity expects to be entitled. Depending on whether certain criteria are met, revenue should be recognized either over time, in a manner that depicts the entity’s performance, or at a point in time, when control of the goods or services are transferred to the customer. ASU 2014-09 provides that an entity should apply the following steps: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. In addition, the existing requirements for the recognition of a gain or loss on the transfer of non-financial assets that are not in a contract with a customer are amended to be consistent with the guidance on recognition and measurement in ASU 2014-09. The amendments of ASU 2014-09 may be applied either retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application. If the transition method of application is elected, the entity should also provide the additional disclosures in reporting periods that include the date of initial application of (1) the amount by which each financial statement line item is affected in the current reporting period, as compared to the guidance that was in effect before the change, and (2) an explanation of the reasons for significant changes. ASU 2015-14, “Revenue from Contracts with Customers (Topic 606)-Deferral of the Effective Date,” issued in August 2015, defers the effective date of ASU 2014-09 by one year. ASU 2015-14 provides that the amendments of ASU 2014-09 become effective for interim and annual periods beginning after December 15, 2017. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. All subsequently issued ASUs which provide additional guidance and clarifications to various aspects of FASB ASC Topic 606 will become effective when the amendments of ASU 2014-09 become effective. Trustmark plans to adopt these amendments during the first quarter of 2018. Management is continuing to evaluate the impact ASU 2014-09 will have on Trustmark’s consolidated financial statements as well as the most appropriate transition method of application. Based on this evaluation to date, Management has determined that the majority of the revenues earned by Trustmark are not within the scope of ASU 2014-09. Management also believes that for most revenue streams within the scope of ASU 2014-09, the amendments will not change the timing of when the revenue is recognized. Management will continue to evaluate the impact the adoption of ASU 2014-09 will have on Trustmark’s consolidated financial statements, focusing on noninterest income sources within the scope of ASU 2014-09 as well as new disclosures required by these amendments; however, the adoption of ASU 2014-09 is not expected to have a material impact on Trustmark’s consolidated financial statements.