Accounting Policies Recently Adopted and Pending Accounting Pronouncements	3 Months Ended
Mar. 31, 2012
Accounting Policies Recently Adopted and Pending Accounting Pronouncements [Abstract]
Accounting Policies Recently Adopted and Pending Accounting Pronouncements	Note 19 -- Accounting Policies Recently Adopted and Pending Accounting Pronouncements ASU 2011-12, “Comprehensive Income (Topic 220): Deferral of the Effective Date for Amendments to the Presentation of Reclassification of Items Out of Accumulated Other Comprehensive Income in Accounting Standards Update No. 2011-05.” ASU 2011-12 defers the effective date of the requirement of ASU 2011-05 to present separate line items on the income statement for reclassification adjustments of items out of accumulated other comprehensive income into net income. ASU 2011-12 was issued to allow the FASB time to redeliberate whether to present on the face of the financial statements the effects of reclassifications out of accumulated other comprehensive income on the components of net income and other comprehensive income for all periods presented. Entities are still required to present reclassification adjustments within other comprehensive income either on the face of the statement that reports other comprehensive income or in the notes to the financial statements. All other requirements of ASU 2011-05 are not affected by ASU 2011-12. The requirements of ASU 2011-05, as amended by ASU 2011-12, became effective for Trustmark's financial statements beginning January 1, 2012. For Trustmark, the impact of the ASU is a change in presentation only and did not have a significant impact on Trustmark's consolidated financial statements. ASU 2011-08, “Intangibles – Goodwill and Other (Topic 350): Testing Goodwill for Impairment.” Issued in September 2011, ASU 2011-08 amends the guidance in ASC 350-202 on testing goodwill for impairment. Under the revised guidance, entities testing goodwill for impairment have the option of performing a qualitative assessment before calculating the fair value of the reporting unit (i.e., step 1 of the goodwill impairment test). If entities determine, on the basis of qualitative factors, that the fair value of the reporting unit is more likely than not less than the carrying amount, the two-step impairment test would be required. The ASU does not change how goodwill is calculated or assigned to reporting units, nor does it revise the requirement to test goodwill annually for impairment. In addition, the ASU does not amend the requirement to test goodwill for impairment between annual tests if events or circumstances warrant; however, it does revise the examples of events and circumstances that an entity should consider. The amendments became effective for Trustmark's annual goodwill impairment tests beginning January 1, 2012. The adoption of ASU 2011-08 did not have an impact on Trustmark's consolidated financial statements. ASU 2011-05, “Comprehensive Income (Topic 220): Presentation of Comprehensive Income.” ASU 2011-05 amends the FASB Accounting Standards Codification (Codification) to allow an entity the option to present the total of comprehensive income, the components of net income, and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. In both choices, an entity is required to present each component of net income along with total net income, each component of other comprehensive income along with a total for other comprehensive income, and a total amount for comprehensive income. ASU 2011-05 eliminates the option to present the components of other comprehensive income as part of the statement of changes in stockholders' equity. The amendments to the Codification in the ASU do not change the items that must be reported in other comprehensive income or when an item of other comprehensive income must be reclassified to net income. ASU 2011-05 should be applied retrospectively. Early adoption is permitted. The ASU became effective for Trustmark's financial statements beginning January 1, 2012. For Trustmark, the impact of the ASU is a change in presentation only and did not have a significant impact on Trustmark's consolidated financial statements. ASU 2011-04, “Fair Value Measurement: Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRSs.” The ASU is the result of joint efforts by the FASB and IASB to develop a single, converged fair value framework on how to measure fair value and on what disclosures to provide about fair value measurements. While the ASU is largely consistent with existing fair value measurement principles in U.S. GAAP, it expands existing disclosure requirements for fair value measurements and makes other amendments. Many of these amendments were made to eliminate unnecessary wording differences between U.S. GAAP and IFRSs. However, some could change how fair value measurement guidance is applied. The ASU became effective for Trustmark's financial statements beginning January 1, 2012, and did not have a significant impact on Trustmark's consolidated financial statements. The required disclosures are reported in Note 16 – Fair Value. ASU 2011-03, “Transfers and Servicing (Topic 860): Reconsideration of Effective Control for Repurchase Agreements.” The ASU eliminates from U.S. GAAP the requirement for entities to consider whether a transferor has the ability to repurchase the financial assets in a repurchase agreement. This requirement was one of the criteria that entities used to determine whether the transferor maintained effective control. Although entities must consider all the effective-control criteria under ASC 860, the elimination of this requirement may lead to more conclusions that a repurchase arrangement should be accounted for as a secured borrowing rather than as a sale. The guidance should be applied prospectively to transactions or modifications of existing transactions that occur on or after the effective date. The ASU became effective for Trustmark's financial statements beginning January 1, 2012, and did not have a significant impact on Trustmark's consolidated financial statements.

Note 19 -- Accounting Policies Recently Adopted and Pending Accounting Pronouncements

ASU 2011-12, “Comprehensive Income (Topic 220): Deferral of the Effective Date for Amendments to the Presentation of Reclassification of Items Out of Accumulated Other Comprehensive Income in Accounting Standards Update No. 2011-05.” ASU 2011-12 defers the effective date of the requirement of ASU 2011-05 to present separate line items on the income statement for reclassification adjustments of items out of accumulated other comprehensive income into net income. ASU 2011-12 was issued to allow the FASB time to redeliberate whether to present on the face of the financial statements the effects of reclassifications out of accumulated other comprehensive income on the components of net income and other comprehensive income for all periods presented. Entities are still required to present reclassification adjustments within other comprehensive income either on the face of the statement that reports other comprehensive income or in the notes to the financial statements. All other requirements of ASU 2011-05 are not affected by ASU 2011-12. The requirements of ASU 2011-05, as amended by ASU 2011-12, became effective for Trustmark's financial statements beginning January 1, 2012. For Trustmark, the impact of the ASU is a change in presentation only and did not have a significant impact on Trustmark's consolidated financial statements.

ASU 2011-08, “Intangibles – Goodwill and Other (Topic 350): Testing Goodwill for Impairment.” Issued in September 2011, ASU 2011-08 amends the guidance in ASC 350-202 on testing goodwill for impairment. Under the revised guidance, entities testing goodwill for impairment have the option of performing a qualitative assessment before calculating the fair value of the reporting unit (i.e., step 1 of the goodwill impairment test). If entities determine, on the basis of qualitative factors, that the fair value of the reporting unit is more likely than not less than the carrying amount, the two-step impairment test would be required. The ASU does not change how goodwill is calculated or assigned to reporting units, nor does it revise the requirement to test goodwill annually for impairment. In addition, the ASU does not amend the requirement to test goodwill for impairment between annual tests if events or circumstances warrant; however, it does revise the examples of events and circumstances that an entity should consider. The amendments became effective for Trustmark's annual goodwill impairment tests beginning January 1, 2012. The adoption of ASU 2011-08 did not have an impact on Trustmark's consolidated financial statements.

ASU 2011-05, “Comprehensive Income (Topic 220): Presentation of Comprehensive Income.” ASU 2011-05 amends the FASB Accounting Standards Codification (Codification) to allow an entity the option to present the total of comprehensive income, the components of net income, and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. In both choices, an entity is required to present each component of net income along with total net income, each component of other comprehensive income along with a total for other comprehensive income, and a total amount for comprehensive income. ASU 2011-05 eliminates the option to present the components of other comprehensive income as part of the statement of changes in stockholders' equity. The amendments to the Codification in the ASU do not change the items that must be reported in other comprehensive income or when an item of other comprehensive income must be reclassified to net income. ASU 2011-05 should be applied retrospectively. Early adoption is permitted. The ASU became effective for Trustmark's financial statements beginning January 1, 2012. For Trustmark, the impact of the ASU is a change in presentation only and did not have a significant impact on Trustmark's consolidated financial statements.

ASU 2011-04, “Fair Value Measurement: Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRSs.” The ASU is the result of joint efforts by the FASB and IASB to develop a single, converged fair value framework on how to measure fair value and on what disclosures to provide about fair value measurements. While the ASU is largely consistent with existing fair value measurement principles in U.S. GAAP, it expands existing disclosure requirements for fair value measurements and makes other amendments. Many of these amendments were made to eliminate unnecessary wording differences between U.S. GAAP and IFRSs. However, some could change how fair value measurement guidance is applied. The ASU became effective for Trustmark's financial statements beginning January 1, 2012, and did not have a significant impact on Trustmark's consolidated financial statements. The required disclosures are reported in Note 16 – Fair Value.

ASU 2011-03, “Transfers and Servicing (Topic 860): Reconsideration of Effective Control for Repurchase Agreements.” The ASU eliminates from U.S. GAAP the requirement for entities to consider whether a transferor has the ability to repurchase the financial assets in a repurchase agreement. This requirement was one of the criteria that entities used to determine whether the transferor maintained effective control. Although entities must consider all the effective-control criteria under ASC 860, the elimination of this requirement may lead to more conclusions that a repurchase arrangement should be accounted for as a secured borrowing rather than as a sale. The guidance should be applied prospectively to transactions or modifications of existing transactions that occur on or after the effective date. The ASU became effective for Trustmark's financial statements beginning January 1, 2012, and did not have a significant impact on Trustmark's consolidated financial statements.