Contingencies	3 Months Ended
Mar. 31, 2013
Contingencies [Abstract]
Contingencies	Note 12 – Contingencies Lending Related Letters of credit are conditional commitments issued by Trustmark to insure the performance of a customer to a third party. Trustmark issues financial and performance standby letters of credit in the normal course of business in order to fulfill the financing needs of its customers. A financial standby letter of credit irrevocably obligates Trustmark to pay a third-party beneficiary when a customer fails to repay an outstanding loan or debt instrument. A performance standby letter of credit irrevocably obligates Trustmark to pay a third-party beneficiary when a customer fails to perform some contractual, nonfinancial obligation. When issuing letters of credit, Trustmark uses essentially the same policies regarding credit risk and collateral, which are followed in the lending process. At March 31, 2013 and 2012, Trustmark's maximum exposure to credit loss in the event of nonperformance by the other party for letters of credit was $156.1 million and $161.7 million, respectively. These amounts consist primarily of commitments with maturities of less than three years, which have an immaterial carrying value. Trustmark holds collateral to support standby letters of credit when deemed necessary. As of March 31, 2013, the fair value of collateral held was $52.7 million. Legal Proceedings Trustmark's wholly-owned subsidiary, TNB, has been named as a defendant in two lawsuits related to the collapse of the Stanford Financial Group. The first is a purported class action complaint that was filed on August 23, 2009 in the District Court of Harris County, Texas, by Peggy Roif Rotstain, Guthrie Abbott, Catherine Burnell, Steven Queyrouze, Jaime Alexis Arroyo Bornstein and Juan C. Olano, on behalf of themselves and all others similarly situated, naming TNB and four other financial institutions unaffiliated with Trustmark as defendants. The complaint seeks to recover (i) alleged fraudulent transfers from each of the defendants in the amount of fees and other monies received by each defendant from entities controlled by R. Allen Stanford (collectively, the "Stanford Financial Group") and (ii) damages allegedly attributable to alleged conspiracies by one or more of the defendants with the Stanford Financial Group to commit fraud and/or aid and abet fraud on the asserted grounds that defendants knew or should have known the Stanford Financial Group was conducting an illegal and fraudulent scheme. Plaintiffs have demanded a jury trial. Plaintiffs did not quantify damages. In November 2009, the lawsuit was removed to federal court by certain defendants and then transferred by the United States Panel on Multidistrict Litigation to federal court in the Northern District of Texas (Dallas) where multiple Stanford related matters are being consolidated for pre-trial proceedings. In May 2010, all defendants (including TNB) filed motions to dismiss the lawsuit, and the motions to dismiss have been fully briefed by all parties. The court has not yet ruled on the defendants' motions to dismiss. In August 2010, the court authorized and approved the formation of an Official Stanford Investors Committee to represent the interests of Stanford investors and, under certain circumstances, to file legal actions for the benefit of Stanford investors. In December 2011, the Official Stanford Investors Committee ("OSIC") filed a motion to intervene in this action. In September 2012, the district court referred the case to a magistrate judge for hearing and determination of certain pretrial issues. In December 2012, the court granted the OSIC's motion to intervene, and the OSIC filed an Intervenor Complaint against one of the other defendant financial institutions. In February 2013, the OSIC filed an additional Intervenor Complaint that asserts claims against TNB and the remaining defendant financial institutions. The OSIC seeks to recover: (i) alleged fraudulent transfers in the amount of the fees each of the defendants allegedly received from Stanford Financial Group, the profits each of the defendants allegedly made from Stanford Financial Group deposits, and other monies each of the defendants allegedly received from Stanford Financial Group; (ii) damages attributable to alleged conspiracies by each of the defendants with the Stanford Financial Group to commit fraud and/or aid and abet fraud and conversion on the asserted grounds that the defendants knew or should have known the Stanford Financial Group was conducting an illegal and fraudulent scheme; and (iii) punitive damages. The OSIC did not quantify damages. The second Stanford-related lawsuit was filed on December 14, 2009 in the District Court of Ascension Parish, Louisiana, individually by Harold Jackson, Paul Blaine, Carolyn Bass Smith, Christine Nichols, and Ronald and Ramona Hebert naming TNB (misnamed as Trust National Bank) and other individuals and entities not affiliated with Trustmark as defendants. The complaint seeks to recover the money lost by these individual plaintiffs as a result of the collapse of the Stanford Financial Group (in addition to other damages) under various theories and causes of action, including negligence, breach of contract, breach of fiduciary duty, negligent misrepresentation, detrimental reliance, conspiracy, and violation of Louisiana's uniform fiduciary, securities, and racketeering laws. The complaint does not quantify the amount of money the plaintiffs seek to recover. In January 2010, the lawsuit was removed to federal court by certain defendants and then transferred by the United States Panel on Multidistrict Litigation to federal court in the Northern District of Texas (Dallas) where multiple Stanford related matters are being consolidated for pre-trial proceedings. On March 29, 2010, the court stayed the case. TNB filed a motion to lift the stay, which was denied on February 28, 2012. In September 2012, the district court referred the case to a magistrate judge for hearing and determination of certain pretrial issues. TNB's relationship with the Stanford Financial Group began as a result of Trustmark's acquisition of a Houston-based bank in August 2006, and consisted of correspondent banking and other traditional banking services in the ordinary course of business. Both Stanford-related lawsuits are in their preliminary stages and have been previously disclosed by Trustmark. TNB is the defendant in two putative class actions challenging TNB's practices regarding "overdraft" or "non-sufficient funds" fees charged by TNB in connection with customer use of debit cards, including TNB's order of processing transactions, notices and calculations of charges, and calculations of fees. Kathy D. White v. TNB was filed in Tennessee state court in Memphis, Tennessee and was removed on June 19, 2012 to the United States District Court for the Western District of Tennessee. (Plaintiff Kathy White had filed an earlier, virtually identical action that was voluntarily dismissed.) Leroy Jenkins v. TNB was filed on June 4, 2012 in the United States District Court for the Southern District of Mississippi. The White and Jenkins pleadings are matters of public record in the files of the courts. In both cases, the plaintiffs purport to represent classes of similarly-situated customers of TNB. The White complaint asserts claims of breach of contract, breach of a duty of good faith and fair dealing, unconscionability, conversion, and unjust enrichment. The Jenkins complaint originally included similar allegations as well as federal-law claims under the Electronic Funds Transfer Act (EFTA) and RICO; however, the RICO claims were voluntarily dismissed from the case on January 9, 2013. Each of these complaints seeks the imposition of a constructive trust and unquantified damages. These complaints are largely patterned after similar lawsuits that have been filed against other banks across the country. On July 19, 2012, the plaintiff in the White case filed an amended complaint to add plaintiffs from Mississippi and also to add federal EFTA claims. Trustmark contends that amended complaint was procedurally improper. On October 4, 2012, the plaintiff in the White case moved for leave to add two Tennessee plaintiffs. That motion is pending for decision. Trustmark has filed preliminary dismissal and venue transfer motions, and discovery has begun, in the White case; the Jenkins case has also entered the active discovery stage. Trustmark and its subsidiaries are also parties to other lawsuits and other claims that arise in the ordinary course of business. Some of the lawsuits assert claims related to the lending, collection, servicing, investment, trust and other business activities, and some of the lawsuits allege substantial claims for damages. All pending legal proceedings described above are being vigorously contested. In the regular course of business, Management evaluates estimated losses or costs related to litigation, and provision is made for anticipated losses whenever Management believes that such losses are probable and can be reasonably estimated. At the present time, Management believes, based on the advice of legal counsel and Management's evaluation, that (i) the final resolution of pending legal proceedings described above will not, individually or in the aggregate, have a material impact on Trustmark's consolidated financial position or results of operations and (ii) a loss in any such case is not probable at this time, and thus no accrual is required under FASB Accounting Standards Codification Topic 450-20 (ASC 450). In addition, given the preliminary nature of these matters and the lack of any quantification by plaintiffs of the relief being sought, to the extent that a loss in any such matter may be viewed as reasonably possible under ASC 450, it is not possible at this time to provide an estimate of any such possible loss (or range of possible loss) for any such matter.

Note 12 – Contingencies

Lending Related

Letters of credit are conditional commitments issued by Trustmark to insure the performance of a customer to a third party. Trustmark issues financial and performance standby letters of credit in the normal course of business in order to fulfill the financing needs of its customers. A financial standby letter of credit irrevocably obligates Trustmark to pay a third-party beneficiary when a customer fails to repay an outstanding loan or debt instrument. A performance standby letter of credit irrevocably obligates Trustmark to pay a third-party beneficiary when a customer fails to perform some contractual, nonfinancial obligation. When issuing letters of credit, Trustmark uses essentially the same policies regarding credit risk and collateral, which are followed in the lending process. At March 31, 2013 and 2012, Trustmark's maximum exposure to credit loss in the event of nonperformance by the other party for letters of credit was $156.1 million and $161.7 million, respectively. These amounts consist primarily of commitments with maturities of less than three years, which have an immaterial carrying value. Trustmark holds collateral to support standby letters of credit when deemed necessary. As of March 31, 2013, the fair value of collateral held was $52.7 million.

Legal Proceedings

Trustmark's wholly-owned subsidiary, TNB, has been named as a defendant in two lawsuits related to the collapse of the Stanford Financial Group. The first is a purported class action complaint that was filed on August 23, 2009 in the District Court of Harris County, Texas, by Peggy Roif Rotstain, Guthrie Abbott, Catherine Burnell, Steven Queyrouze, Jaime Alexis Arroyo Bornstein and Juan C. Olano, on behalf of themselves and all others similarly situated, naming TNB and four other financial institutions unaffiliated with Trustmark as defendants. The complaint seeks to recover (i) alleged fraudulent transfers from each of the defendants in the amount of fees and other monies received by each defendant from entities controlled by R. Allen Stanford (collectively, the "Stanford Financial Group") and (ii) damages allegedly attributable to alleged conspiracies by one or more of the defendants with the Stanford Financial Group to commit fraud and/or aid and abet fraud on the asserted grounds that defendants knew or should have known the Stanford Financial Group was conducting an illegal and fraudulent scheme. Plaintiffs have demanded a jury trial. Plaintiffs did not quantify damages. In November 2009, the lawsuit was removed to federal court by certain defendants and then transferred by the United States Panel on Multidistrict Litigation to federal court in the Northern District of Texas (Dallas) where multiple Stanford related matters are being consolidated for pre-trial proceedings. In May 2010, all defendants (including TNB) filed motions to dismiss the lawsuit, and the motions to dismiss have been fully briefed by all parties. The court has not yet ruled on the defendants' motions to dismiss. In August 2010, the court authorized and approved the formation of an Official Stanford Investors Committee to represent the interests of Stanford investors and, under certain circumstances, to file legal actions for the benefit of Stanford investors. In December 2011, the Official Stanford Investors Committee ("OSIC") filed a motion to intervene in this action. In September 2012, the district court referred the case to a magistrate judge for hearing and determination of certain pretrial issues. In December 2012, the court granted the OSIC's motion to intervene, and the OSIC filed an Intervenor Complaint against one of the other defendant financial institutions. In February 2013, the OSIC filed an additional Intervenor Complaint that asserts claims against TNB and the remaining defendant financial institutions. The OSIC seeks to recover: (i) alleged fraudulent transfers in the amount of the fees each of the defendants allegedly received from Stanford Financial Group, the profits each of the defendants allegedly made from Stanford Financial Group deposits, and other monies each of the defendants allegedly received from Stanford Financial Group; (ii) damages attributable to alleged conspiracies by each of the defendants with the Stanford Financial Group to commit fraud and/or aid and abet fraud and conversion on the asserted grounds that the defendants knew or should have known the Stanford Financial Group was conducting an illegal and fraudulent scheme; and (iii) punitive damages. The OSIC did not quantify damages.

The second Stanford-related lawsuit was filed on December 14, 2009 in the District Court of Ascension Parish, Louisiana, individually by Harold Jackson, Paul Blaine, Carolyn Bass Smith, Christine Nichols, and Ronald and Ramona Hebert naming TNB (misnamed as Trust National Bank) and other individuals and entities not affiliated with Trustmark as defendants. The complaint seeks to recover the money lost by these individual plaintiffs as a result of the collapse of the Stanford Financial Group (in addition to other damages) under various theories and causes of action, including negligence, breach of contract, breach of fiduciary duty, negligent misrepresentation, detrimental reliance, conspiracy, and violation of Louisiana's uniform fiduciary, securities, and racketeering laws. The complaint does not quantify the amount of money the plaintiffs seek to recover. In January 2010, the lawsuit was removed to federal court by certain defendants and then transferred by the United States Panel on Multidistrict Litigation to federal court in the Northern District of Texas (Dallas) where multiple Stanford related matters are being consolidated for pre-trial proceedings. On March 29, 2010, the court stayed the case. TNB filed a motion to lift the stay, which was denied on February 28, 2012. In September 2012, the district court referred the case to a magistrate judge for hearing and determination of certain pretrial issues.

TNB's relationship with the Stanford Financial Group began as a result of Trustmark's acquisition of a Houston-based bank in August 2006, and consisted of correspondent banking and other traditional banking services in the ordinary course of business. Both Stanford-related lawsuits are in their preliminary stages and have been previously disclosed by Trustmark.

TNB is the defendant in two putative class actions challenging TNB's practices regarding "overdraft" or "non-sufficient funds" fees charged by TNB in connection with customer use of debit cards, including TNB's order of processing transactions, notices and calculations of charges, and calculations of fees. Kathy D. White v. TNB was filed in Tennessee state court in Memphis, Tennessee and was removed on June 19, 2012 to the United States District Court for the Western District of Tennessee. (Plaintiff Kathy White had filed an earlier, virtually identical action that was voluntarily dismissed.) Leroy Jenkins v. TNB was filed on June 4, 2012 in the United States District Court for the Southern District of Mississippi. The White and Jenkins pleadings are matters of public record in the files of the courts. In both cases, the plaintiffs purport to represent classes of similarly-situated customers of TNB. The White complaint asserts claims of breach of contract, breach of a duty of good faith and fair dealing, unconscionability, conversion, and unjust enrichment. The Jenkins complaint originally included similar allegations as well as federal-law claims under the Electronic Funds Transfer Act (EFTA) and RICO; however, the RICO claims were voluntarily dismissed from the case on January 9, 2013. Each of these complaints seeks the imposition of a constructive trust and unquantified damages. These complaints are largely patterned after similar lawsuits that have been filed against other banks across the country. On July 19, 2012, the plaintiff in the White case filed an amended complaint to add plaintiffs from Mississippi and also to add federal EFTA claims. Trustmark contends that amended complaint was procedurally improper. On October 4, 2012, the plaintiff in the White case moved for leave to add two Tennessee plaintiffs. That motion is pending for decision. Trustmark has filed preliminary dismissal and venue transfer motions, and discovery has begun, in the White case; the Jenkins case has also entered the active discovery stage.

Trustmark and its subsidiaries are also parties to other lawsuits and other claims that arise in the ordinary course of business. Some of the lawsuits assert claims related to the lending, collection, servicing, investment, trust and other business activities, and some of the lawsuits allege substantial claims for damages.

All pending legal proceedings described above are being vigorously contested. In the regular course of business, Management evaluates estimated losses or costs related to litigation, and provision is made for anticipated losses whenever Management believes that such losses are probable and can be reasonably estimated. At the present time, Management believes, based on the advice of legal counsel and Management's evaluation, that (i) the final resolution of pending legal proceedings described above will not, individually or in the aggregate, have a material impact on Trustmark's consolidated financial position or results of operations and (ii) a loss in any such case is not probable at this time, and thus no accrual is required under FASB Accounting Standards Codification Topic 450-20 (ASC 450). In addition, given the preliminary nature of these matters and the lack of any quantification by plaintiffs of the relief being sought, to the extent that a loss in any such matter may be viewed as reasonably possible under ASC 450, it is not possible at this time to provide an estimate of any such possible loss (or range of possible loss) for any such matter.