Contingencies	3 Months Ended
Mar. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Contingencies	Note 13 – Contingencies Lending Related Trustmark makes commitments to extend credit and issues standby and commercial letters of credit (letters of credit) in the normal course of business in order to fulfill the financing needs of its customers. The carrying amount of commitments to extend credit and letters of credit approximates the fair value of such financial instruments. Commitments to extend credit are agreements to lend money to customers pursuant to certain specified conditions. Commitments generally have fixed expiration dates or other termination clauses. Because many of these commitments are expected to expire without being fully drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The exposure to credit loss in the event of nonperformance by the other party to the commitments to extend credit is represented by the contract amount of those instruments. Trustmark applies the same credit policies and standards as it does in the lending process when making these commitments. The collateral obtained is based upon the nature of the transaction and the assessed creditworthiness of the borrower. At March 31, 2019 and 2018, Trustmark had unused commitments to extend credit of $4.011 billion and $3.280 billion, respectively. Letters of credit are conditional commitments issued by Trustmark to insure the performance of a customer to a third-party. 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 the same policies regarding credit risk and collateral, which are followed in the lending process. At March 31, 2019 and 2018, Trustmark’s maximum exposure to credit loss in the event of nonperformance by the other party for letters of credit was $106.5 million and $103.5 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, 2019 and 2018, the fair value of collateral held was $30.0 million and $27.8 million, respectively. Legal Proceedings Trustmark’s wholly-owned subsidiary, TNB, has been named as a defendant in three 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 (collectively, Class Plaintiffs), 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. In August 2010, the court authorized and approved the formation of an Official Stanford Investors Committee (OSIC) 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 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 a second 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. In July 2013, all defendants (including TNB) filed motions to dismiss the OSIC’s claims. In March 2015, the court entered an order authorizing the parties to conduct discovery regarding class certification, staying all other discovery and setting a deadline for the parties to complete briefing on class certification issues. In April 2015, the court granted in part and denied in part the defendants’ motions to dismiss the Class Plaintiffs’ claims and the OSIC’s claims. The court dismissed all of the Class Plaintiffs’ fraudulent transfer claims and dismissed certain of the OSIC’s claims. The court denied the motions by TNB and the other financial institution defendants to dismiss the OSIC’s constructive fraudulent transfer claims. On June 23, 2015, the court allowed the Class Plaintiffs to file a Second Amended Class Action Complaint (SAC), which asserted new claims against TNB and certain of the other defendants for (i) aiding, abetting and participating in a fraudulent scheme, (ii) aiding, abetting and participating in violations of the Texas Securities Act, (iii) aiding, abetting and participating in breaches of fiduciary duty, (iv) aiding, abetting and participating in conversion and (v) conspiracy. On July 14, 2015, the defendants (including TNB) filed motions to dismiss the SAC and to reconsider the court’s prior denial to dismiss the OSIC’s constructive fraudulent transfer claims against TNB and the other financial institutions that are defendants in the action. On July 27, 2016, the court denied the motion by TNB and the other financial institution defendants to dismiss the SAC and also denied the motion by TNB and the other financial institution defendants to reconsider the court’s prior denial to dismiss the OSIC’s constructive fraudulent transfer claims. On August 24, 2016, TNB filed its answer to the SAC. On October 20, 2017, the OSIC filed a motion seeking an order lifting the discovery stay and establishing a trial schedule. On November 7, 2017, the court denied the OSIC’s motion seeking class certification and designation of class representatives and counsel, finding that common issues of fact did not predominate. The court granted the OSIC’s motion to lift the discovery stay that it had previously ordered. 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. On April 11, 2016, Trustmark learned that a third Stanford-related lawsuit had been filed on that date in the Superior Court of Justice in Ontario, Canada, by The Toronto-Dominion Bank (“TD Bank”), naming TNB and three other financial institutions not affiliated with Trustmark as defendants. The complaint seeks a declaration specifying the degree to which each of TNB and the other defendants are liable in respect of any loss and damage for which TD Bank is found to be liable in a litigation commenced against TD Bank brought by the Joint Liquidators of Stanford International Bank Limited in the Superior Court of Justice, Commercial List in Ontario, Canada (the “Joint Liquidators’ Action”), as well as contribution and indemnity in respect of any judgment, interest and costs TD Bank is ordered to pay in the Joint Liquidators’ Action. To date, TNB has not been served in connection with this action. 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. All Stanford-related lawsuits are in pre-trial stages. 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 accordance FASB ASC Topic 450-20, “Loss Contingencies,” Trustmark will establish an accrued liability for litigation matters when those matters present loss contingencies that are both probable and reasonably estimable. At the present time, Trustmark believes, based on its evaluation and the advice of legal counsel, that a loss in any such proceeding is not probable and a reasonable estimate cannot reasonably be made.

Contingencies

3 Months Ended

Mar. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Note 13 – Contingencies

Lending Related

Trustmark makes commitments to extend credit and issues standby and commercial letters of credit (letters of credit) in the normal course of business in order to fulfill the financing needs of its customers. The carrying amount of commitments to extend credit and letters of credit approximates the fair value of such financial instruments.

Commitments to extend credit are agreements to lend money to customers pursuant to certain specified conditions. Commitments generally have fixed expiration dates or other termination clauses. Because many of these commitments are expected to expire without being fully drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The exposure to credit loss in the event of nonperformance by the other party to the commitments to extend credit is represented by the contract amount of those instruments. Trustmark applies the same credit policies and standards as it does in the lending process when making these commitments. The collateral obtained is based upon the nature of the transaction and the assessed creditworthiness of the borrower. At March 31, 2019 and 2018, Trustmark had unused commitments to extend credit of $4.011 billion and $3.280 billion, respectively.

Letters of credit are conditional commitments issued by Trustmark to insure the performance of a customer to a third-party. 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 the same policies regarding credit risk and collateral, which are followed in the lending process. At March 31, 2019 and 2018, Trustmark’s maximum exposure to credit loss in the event of nonperformance by the other party for letters of credit was $106.5 million and $103.5 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, 2019 and 2018, the fair value of collateral held was $30.0 million and $27.8 million, respectively.

Legal Proceedings

Trustmark’s wholly-owned subsidiary, TNB, has been named as a defendant in three 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 (collectively, Class Plaintiffs), 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. In August 2010, the court authorized and approved the formation of an Official Stanford Investors Committee (OSIC) 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 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 a second 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.

In July 2013, all defendants (including TNB) filed motions to dismiss the OSIC’s claims. In March 2015, the court entered an order authorizing the parties to conduct discovery regarding class certification, staying all other discovery and setting a deadline for the parties to complete briefing on class certification issues. In April 2015, the court granted in part and denied in part the defendants’ motions to dismiss the Class Plaintiffs’ claims and the OSIC’s claims. The court dismissed all of the Class Plaintiffs’ fraudulent transfer claims and dismissed certain of the OSIC’s claims. The court denied the motions by TNB and the other financial institution defendants to dismiss the OSIC’s constructive fraudulent transfer claims.

On June 23, 2015, the court allowed the Class Plaintiffs to file a Second Amended Class Action Complaint (SAC), which asserted new claims against TNB and certain of the other defendants for (i) aiding, abetting and participating in a fraudulent scheme, (ii) aiding, abetting and participating in violations of the Texas Securities Act, (iii) aiding, abetting and participating in breaches of fiduciary duty, (iv) aiding, abetting and participating in conversion and (v) conspiracy. On July 14, 2015, the defendants (including TNB) filed motions to dismiss the SAC and to reconsider the court’s prior denial to dismiss the OSIC’s constructive fraudulent transfer claims against TNB and the other financial institutions that are defendants in the action. On July 27, 2016, the court denied the motion by TNB and the other financial institution defendants to dismiss the SAC and also denied the motion by TNB and the other financial institution defendants to reconsider the court’s prior denial to dismiss the OSIC’s constructive fraudulent transfer claims. On August 24, 2016, TNB filed its answer to the SAC. On October 20, 2017, the OSIC filed a motion seeking an order lifting the discovery stay and establishing a trial schedule. On November 7, 2017, the court denied the OSIC’s motion seeking class certification and designation of class representatives and counsel, finding that common issues of fact did not predominate. The court granted the OSIC’s motion to lift the discovery stay that it had previously ordered.

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.

On April 11, 2016, Trustmark learned that a third Stanford-related lawsuit had been filed on that date in the Superior Court of Justice in Ontario, Canada, by The Toronto-Dominion Bank (“TD Bank”), naming TNB and three other financial institutions not affiliated with Trustmark as defendants. The complaint seeks a declaration specifying the degree to which each of TNB and the other defendants are liable in respect of any loss and damage for which TD Bank is found to be liable in a litigation commenced against TD Bank brought by the Joint Liquidators of Stanford International Bank Limited in the Superior Court of Justice, Commercial List in Ontario, Canada (the “Joint Liquidators’ Action”), as well as contribution and indemnity in respect of any judgment, interest and costs TD Bank is ordered to pay in the Joint Liquidators’ Action. To date, TNB has not been served in connection with this action.

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. All Stanford-related lawsuits are in pre-trial stages.

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 accordance FASB ASC Topic 450-20, “Loss Contingencies,” Trustmark will establish an accrued liability for litigation matters when those matters present loss contingencies that are both probable and reasonably estimable. At the present time, Trustmark believes, based on its evaluation and the advice of legal counsel, that a loss in any such proceeding is not probable and a reasonable estimate cannot reasonably be made.