Trustmark (TRMK) 10-K 20 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Jan. 31, 2020	Jun. 28, 2019
Cover [Abstract]
Entity Registrant Name	TRUSTMARK CORP
Entity Central Index Key	0000036146
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,217
Entity Common Stock, Shares Outstanding		63,843,049
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Trading Symbol	TRMK
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock, no par value
Security Exchange Name	NASDAQ
Entity File Number	000-3683
Entity Incorporation, State or Country Code	MS
Entity Tax Identification Number	64-0471500
Entity Address, Address Line One	248 East Capitol Street
Entity Address, City or Town	Jackson
Entity Address, State or Province	MS
Entity Address, Postal Zip Code	39201
City Area Code	601
Local Phone Number	208-5111
Document Annual Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the Proxy Statement for Trustmark’s 2020 Annual Meeting of Shareholders to be held April 28, 2020 are incorporated by reference into Part III of the Form 10-K report.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 358,916	$ 349,561
Federal funds sold and securities purchased under reverse repurchase agreements		830
Securities available for sale (at fair value)	1,602,404	1,811,813
Securities held to maturity (fair value: $746,202-2019; $889,733-2018)	738,099	909,643
Loans held for sale (LHFS)	226,347	153,799
Loans held for investment (LHFI)	9,335,628	8,835,868
Less allowance for loan losses, LHFI	84,277	79,290
Net LHFI	9,251,351	8,756,578
Acquired loans	72,601	106,932
Less allowance for loan losses, acquired loans	815	1,231
Net acquired loans	71,786	105,701
Net LHFI and acquired loans	9,323,137	8,862,279
Premises and equipment, net	189,791	178,668
Mortgage servicing rights	79,394	95,596
Goodwill	379,627	379,627
Identifiable intangible assets, net	7,343	11,112
Other real estate	29,248	34,668
Operating lease right-of-use assets	31,182
Other assets	532,389	498,864
Total Assets	13,497,877	13,286,460
Deposits:
Noninterest-bearing	2,891,215	2,937,594
Interest-bearing	8,354,342	8,426,817
Total deposits	11,245,557	11,364,411
Federal funds purchased and securities sold under repurchase agreements	256,020	50,471
Other borrowings	85,396	79,885
Junior subordinated debt securities	61,856	61,856
Operating lease liabilities	32,354
Other liabilities	155,992	138,384
Total Liabilities	11,837,175	11,695,007
Shareholders' Equity
Common stock, no par value: Authorized: 250,000,000 shares Issued and outstanding: 64,200,111 shares - 2019; 65,834,395 shares - 2018	13,376	13,717
Capital surplus	256,400	309,545
Retained earnings	1,414,526	1,323,870
Accumulated other comprehensive loss, net of tax	(23,600)	(55,679)
Total Shareholders' Equity	1,660,702	1,591,453
Total Liabilities and Shareholders' Equity	$ 13,497,877	$ 13,286,460

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Securities held to maturity, fair value	$ 746,202	$ 889,733
Shareholders' Equity
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, authorized (in shares)	250,000,000	250,000,000
Common stock, issued (in shares)	64,200,111	65,834,395
Common stock, outstanding (in shares)	64,200,111	65,834,395

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Interest Income
Interest and fees on LHFS & LHFI	$ 440,156	$ 395,969		$ 344,625
Interest and fees on acquired loans	8,373	17,115		24,478
Interest on securities:
Taxable	54,649	66,082		76,192
Tax exempt	1,711	2,236		3,001
Interest on federal funds sold and securities purchased under reverse repurchase agreements	240	14		33
Other interest income	5,363	4,196		1,466
Total Interest Income	510,492	485,612		449,795
Interest Expense
Interest on deposits	79,171	53,936		22,717
Interest on federal funds purchased and securities sold under repurchase agreements	1,420	4,788		4,152
Other interest expense	3,312	7,468		15,376
Total Interest Expense	83,903	66,192		42,245
Net Interest Income	426,589	419,420		407,550
Provision for loan losses, LHFI	10,797	17,993		15,094
Provision for loan losses, acquired loans	42	(1,005)		(7,395)
Net Interest Income After Provision for Loan Losses	415,750	402,432		399,851
Noninterest Income
Service charges on deposit accounts	42,603	43,702	[1]	44,003	[1],[2]
Bank card and other fees	31,736	28,905	[1]	28,286	[1],[2]
Mortgage banking, net	29,822	34,674	[1]	29,902	[1],[2]
Insurance commissions	42,396	40,481	[1]	38,168	[1],[2]
Wealth management	30,679	30,338	[1]	30,340	[1],[2]
Other, net	9,809	6,736	[1]	13,949	[1],[2]
Securities gains (losses), net	0	0		15	[1],[2]
Total Noninterest Income	187,045	184,836	[1]	184,663	[1],[2]
Noninterest Expense
Salaries and employee benefits	247,717	238,033		229,265
Defined benefit plan termination				17,644
Services and fees	73,315	66,382		60,893
Net occupancy - premises	26,149	26,703		25,767
Equipment expense	23,733	24,830		24,453
Other real estate expense	3,906	2,002		3,672
FDIC assessment expense	6,444	9,429		11,010
Other expense	47,738	48,036		57,465
Total Noninterest Expense	429,002	415,415		430,169
Income Before Income Taxes	173,793	171,853		154,345
Income taxes	23,333	22,269		48,715
Net Income	$ 150,460	$ 149,584		$ 105,630
Earnings Per Share
Basic	$ 2.33	$ 2.22		$ 1.56
Diluted	$ 2.32	$ 2.21		$ 1.56
[1]	During the first quarter of 2019, Trustmark revised the composition of its operating segments by moving the Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes.  The prior period amounts presented include reclassifications to conform to the current period presentation.
[2]	Trustmark elected the modified retrospective approach of adoption; therefore, prior period balances are presented under legacy GAAP and may not be comparable to current year presentation.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income per consolidated statements of income	$ 150,460	$ 149,584	$ 105,630
Net unrealized gains (losses) on available for sale securities and transferred securities:
Net unrealized holding gains (losses) arising during the period	33,103	(14,416)	(8,641)
Reclassification adjustment for net (gains) losses realized in net income	0	0	(9)
Change in net unrealized holding loss on securities transferred to held to maturity	2,704	2,821	2,915
Pension and other postretirement benefit plans:
Change in the actuarial loss of pension and other postretirement benefit plans	(4,278)	2,806	(760)
Reclassification adjustments for changes realized in net income:
Net change in prior service costs	187	187	154
Recognized net loss due to lump sum settlements	235	122	0
Change in net actuarial loss	597	919	1,211
Recognized net loss due to defined benefit plan termination	0	0	10,907
Derivatives:
Change in the accumulated gain (loss) on effective cash flow hedge derivatives	(109)	373	122
Reclassification adjustment for (gain) loss realized in net income	(360)	(242)	174
Other comprehensive income (loss), net of tax	32,079	(7,430)	6,073
Comprehensive income	$ 182,539	$ 142,154	$ 111,703

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2016	$ 1,520,208	$ 14,091	$ 366,563	$ 1,185,352	$ (45,798)
Balance (in shares) at Dec. 31, 2016		67,628,618
Net income per consolidated statements of income	105,630			105,630
Other comprehensive income (loss), net of tax	6,073				6,073
Cash dividends paid on common stock ($0.92 per share)	(62,795)			(62,795)
Shares withheld to pay taxes, long-term incentive plan	(1,724)	$ 24	(1,748)
Shares withheld to pay taxes, long-term incentive plan (in shares)		117,476
Compensation expense, long-term incentive plan	4,309		4,309
Balance at Dec. 31, 2017	1,571,701	$ 14,115	369,124	1,228,187	(39,725)
Balance (in shares) at Dec. 31, 2017		67,746,094
Net income per consolidated statements of income	149,584			149,584
Other comprehensive income (loss), net of tax	(7,430)				(7,430)
Cash dividends paid on common stock ($0.92 per share)	(62,425)			(62,425)
Shares withheld to pay taxes, long-term incentive plan	(1,426)	$ 25	(1,451)
Shares withheld to pay taxes, long-term incentive plan (in shares)		118,108
Accumulated other comprehensive loss adjustment, Tax Reform Act				8,524	(8,524)
Repurchase and retirement of common stock	(62,421)	$ (423)	(61,998)
Repurchase and retirement of common stock (in shares)		(2,029,807)
Compensation expense, long-term incentive plan	3,870		3,870
Balance at Dec. 31, 2018	$ 1,591,453	$ 13,717	309,545	1,323,870	(55,679)
Balance (in shares) at Dec. 31, 2018	65,834,395	65,834,395
Net income per consolidated statements of income	$ 150,460			150,460
Other comprehensive income (loss), net of tax	32,079				32,079
Cash dividends paid on common stock ($0.92 per share)	(59,804)			(59,804)
Shares withheld to pay taxes, long-term incentive plan	(1,658)	$ 28	(1,686)
Shares withheld to pay taxes, long-term incentive plan (in shares)		134,564
Repurchase and retirement of common stock	(56,615)	$ (369)	(56,246)
Repurchase and retirement of common stock (in shares)		(1,768,848)
Compensation expense, long-term incentive plan	4,787		4,787
Balance at Dec. 31, 2019	$ 1,660,702	$ 13,376	$ 256,400	$ 1,414,526	$ (23,600)
Balance (in shares) at Dec. 31, 2019	64,200,111	64,200,111

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Stockholders Equity [Abstract]
Cash dividends paid on common stock (in dollars per share)	$ 0.92	$ 0.92	$ 0.92

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net income per consolidated statements of income	$ 150,460	$ 149,584	$ 105,630
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses, net	10,839	16,988	7,699
Depreciation and amortization	39,420	38,940	38,471
Net amortization of securities	7,789	9,181	10,964
Securities (gains) losses, net	0	0	(15)	[1],[2]
Gains on sales of loans, net	(27,301)	(21,615)	(18,933)
Compensation expense, long-term incentive plan	4,787	3,870	4,309
Deferred income tax provision	(3,880)	11,740	26,068
Proceeds from sales of loans held for sale	1,431,003	1,114,020	1,197,821
Purchases and originations of loans held for sale	(1,480,752)	(1,052,339)	(1,179,187)
Originations of mortgage servicing rights	(16,711)	(15,759)	(15,860)
Earnings on bank-owned life insurance	(5,592)	(5,358)	(5,025)
Net change in other assets	(30,729)	(1,891)	23,451
Net change in other liabilities	13,276	(1,277)	9,093
Other operating activities, net	23,838	(6,886)	2,121
Net cash from operating activities	116,447	239,198	206,607
Investing Activities
Proceeds from maturities, prepayments and calls of securities held to maturity	173,385	149,308	174,976
Proceeds from maturities, prepayments and calls of securities available for sale	425,260	423,617	467,194
Proceeds from sales of securities available for sale	0	0	27,682
Purchases of securities held to maturity	0	0	(69,989)
Purchases of securities available for sale	(177,739)	(23,901)	(346,159)
Net proceeds from bank-owned life insurance	4,140	1,824	3,623
Net change in federal funds sold and securities purchased under reverse repurchase agreements	830	(215)	6,785
Net change in member bank stock	262	35,451	4,474
Net change in loans	(480,295)	(140,710)	(608,886)
Purchases of premises and equipment	(17,327)	(14,644)	(13,219)
Proceeds from sales of premises and equipment	3,248	772	8,377
Proceeds from sales of other real estate	11,182	20,502	26,849
Purchases of software	(13,412)	(13,195)	(5,498)
Investments in tax credit and other partnerships	(3,426)	(22)	(5,296)
Purchase of insurance book of business	(347)	0	0
Net cash used in business acquisition	0	0	(19,775)
Net cash from investing activities	(74,239)	438,787	(348,862)
Financing Activities
Net change in deposits	(118,854)	786,899	355,342
Net change in federal funds purchased and securities sold under repurchase agreements	205,549	(419,356)	(69,990)
Net change in short-term borrowings	561	(905,396)	(67,451)
Payments on long-term FHLB advances	(68)	(67)	(65)
Payments under finance lease obligations	(1,964)	0	0
Redemption of junior subordinated debt securities	0	0	(3,000)
Common stock dividends	(59,804)	(62,425)	(62,795)
Repurchase and retirement of common stock	(56,615)	(62,421)	0
Shares withheld to pay taxes, long-term incentive plan	(1,658)	(1,426)	(1,724)
Net cash from financing activities	(32,853)	(664,192)	150,317
Net change in cash and cash equivalents	9,355	13,793	8,062
Cash and cash equivalents at beginning of year	349,561	335,768	327,706
Cash and cash equivalents at end of year	$ 358,916	$ 349,561	$ 335,768
[1]	During the first quarter of 2019, Trustmark revised the composition of its operating segments by moving the Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes.  The prior period amounts presented include reclassifications to conform to the current period presentation.
[2]	Trustmark elected the modified retrospective approach of adoption; therefore, prior period balances are presented under legacy GAAP and may not be comparable to current year presentation.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	Note 1 – Significant Accounting Policies Business Trustmark Corporation (Trustmark) is a bank holding company headquartered in Jackson, Mississippi. Through its subsidiaries, Trustmark operates as a financial services organization providing banking and financial solutions to corporate institutions and individual customers through 193 offices in Alabama, Florida, Mississippi, Tennessee and Texas. Basis of Financial Statement Presentation The consolidated financial statements include the accounts of Trustmark and all other entities in which Trustmark has a controlling financial interest. All significant intercompany accounts and transactions have been eliminated in consolidation. The consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (GAAP). The preparation of financial statements in conformity with these accounting principles requires Management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and income and expense during the reporting periods and the related disclosures. Although Management’s estimates contemplate current conditions and how they are expected to change in the future, it is reasonably possible that in 2020 actual conditions could vary from those anticipated, which could affect Trustmark’s financial condition and results of operations. Actual results could differ from those estimates. Securities Securities are classified as either held to maturity or available for sale. Securities are classified as held to maturity and carried at amortized cost when Management has the positive intent and the ability to hold them until maturity. Securities to be held for indefinite periods of time are classified as available for sale and carried at fair value, with the unrealized holding gains and losses reported as a component of other comprehensive income (loss), net of tax. Securities available for sale are used as part of Trustmark’s interest rate risk management strategy and may be sold in response to changes in interest rates, changes in prepayment rates and other factors. Management determines the appropriate classification of securities at the time of purchase. The amortized cost of debt securities classified as securities held to maturity or securities available for sale is adjusted for amortization of premiums and accretion of discounts to maturity of the security using the interest method. Such amortization or accretion is included in interest on securities. Realized gains and losses are determined using the specific identification method and are included in noninterest income as securities gains (losses), net. Securities transferred from the available for sale category to the held to maturity category are recorded at fair value at the date of transfer. Unrealized holding gains or losses associated with the transfer of securities from available for sale to held to maturity are included in the balance of accumulated other comprehensive income (loss), net of tax, in the consolidated balance sheets. These unrealized holding gains or losses are amortized over the remaining life of the security as a yield adjustment in a manner consistent with the amortization or accretion of the original purchase premium or discount on the associated security. Trustmark reviews securities for impairment quarterly. Declines in the fair value of held to maturity and available for sale securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses to the extent the impairment is related to credit losses. The amount of the impairment related to other factors is recognized as a component of other comprehensive income (loss), net of tax. In estimating other-than-temporary impairment losses, Management considers, among other things, the length of time and the extent to which the fair value has been less than cost, the financial condition and near-term prospects of the issuer and Trustmark’s intent and ability to hold the security for a period of time sufficient to allow for any anticipated recovery in fair value. Loans Held for Sale (LHFS) Primarily, all mortgage loans purchased from wholesale customers or originated in Trustmark’s General Banking Segment are considered to be held for sale. In certain circumstances, Trustmark will retain a mortgage loan in its portfolio based on banking relationships or certain investment strategies. Trustmark has elected to account for its LHFS under the fair value option permitted by Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 825, “Financial Instruments,” with interest income on the LHFS reported in interest and fees on LHFS and LHFI. Trustmark reports unrealized gains and losses resulting from changes in the fair value of the LHFS accounted for under the fair value option as noninterest income in mortgage banking, net. LHFS are actively managed and monitored and certain market risks of the loans may be mitigated through the use of derivatives. These derivative instruments are carried at fair value with changes in the fair value reported as noninterest income in mortgage banking, net. Changes in the fair value of the LHFS are largely offset by changes in the fair value of the derivative instruments. Election of the fair value option allows Trustmark to reduce the accounting volatility that would otherwise result from the asymmetry created by accounting for its LHFS at the lower of cost or fair value and the derivative instruments at fair value. Realized gains and losses upon ultimate sale of the loans are reported as noninterest income in mortgage banking, net. Government National Mortgage Association (GNMA) optional repurchase programs allow financial institutions to buy back individual delinquent mortgage loans that meet certain criteria from the securitized loan pool for which the institution provides servicing. At the servicer’s option and without GNMA’s prior authorization, the servicer may repurchase such a delinquent loan for an amount equal to 100 percent of the remaining principal balance of the loan. Under FASB ASC Topic 860, “Transfers and Servicing,” this buy-back option is considered a conditional option until the delinquency criteria are met, at which time the option becomes unconditional. When Trustmark is deemed to have regained effective control over these loans under the unconditional buy-back option, the loans can no longer be reported as sold and must be brought back onto the balance sheet as LHFS, regardless of whether Trustmark intends to exercise the buy-back option. These loans are reported as LHFS with the offsetting liability being reported as short-term borrowings. The fair value option election does not apply to the GNMA optional repurchase loans which do not meet the requirements under FASB ASC Topic 825 to be accounted for under the fair value option. Trustmark defers the upfront loan fees and costs related to the LHFS. In general, the LHFS are only retained on Trustmark’s balance sheet for 30 to 45 days before they are pooled and sold in the secondary market. The difference between deferring these loan fees and costs until the loans are sold and recognizing them in earnings as incurred as required by FASB ASC Subtopic 825-10 is considered immaterial. Deferred loan fees and costs are reflected in the basis of the LHFS and, as such, impact the resulting gain or loss when the loans are sold. Loans Held for Investment (LHFI) LHFI are stated at the amount of unpaid principal, adjusted for the net amount of direct costs and nonrefundable loan fees associated with lending. The net amount of nonrefundable loan origination fees and direct costs associated with the lending process, including commitment fees, is deferred and accreted to interest income over the lives of the loans using a method that approximates the interest method. Interest on LHFI is accrued and recorded as interest income based on the outstanding principal balance. Past due LHFI are loans contractually past due 30 days or more as to principal or interest payments. A LHFI is classified as nonaccrual, and the accrual of interest on such loan is discontinued, when the contractual payment of principal or interest becomes 90 days past due on commercial credits and 120 days past due on non-business purpose credits. In addition, a credit may be placed on nonaccrual at any other time Management has serious doubts about further collectibility of principal or interest according to the contractual terms, even though the loan is currently performing. A LHFI may remain in accrual status if it is in the process of collection and well secured. When a LHFI is placed in nonaccrual status, interest accrued but not received is reversed against interest income. Interest payments received on nonaccrual LHFI are applied against principal under the cost-recovery method, until qualifying for return to accrual status. Under the cost-recovery method, interest income is not recognized until the principal balance is reduced to zero. LHFI are restored to accrual status when the obligation is brought current or has performed in accordance with the contractual terms for a reasonable period of time and the ultimate collectibility of the total contractual principal and interest is no longer in doubt. A LHFI is considered impaired when, based on current information and events, it is probable that Trustmark will be unable to collect all amounts due according to the contractual terms of the loan agreement. In accordance with FASB ASC Subtopic 310-40-35, “Troubled Debt Restructurings by Creditors: Subsequent Measurement,” all loans restructured in a troubled debt restructuring (TDR), without regard to a loan’s accrual status, are impaired loans. Additionally, Trustmark specifically reviews all commercial nonaccrual relationships of $500 thousand or more for impairment. Trustmark considers all commercial nonaccrual relationships of $500 thousand or more, which have been specifically reviewed for impairment and deemed impaired, and all LHFI classified as TDRs to be individually evaluated impaired LHFI. At the time a LHFI that has been specifically reviewed for impairment is deemed to be impaired, the full difference between book value and the most likely estimate of the collateral’s net realizable value is charged off or a specific reserve is established. As subsequent events dictate and estimated net realizable values change, further adjustments may be necessary. Commercial nonaccrual relationships under $500 thousand are not specifically reviewed for impairment due to the insignificant number and dollar amount of these types of loans. Nonaccrual LHFI includes both individually evaluated impaired LHFI as well as smaller balance homogeneous loans that are collectively evaluated for impairment. Consistent with the policy for nonaccrual LHFI, interest payments on impaired LHFI, with the exception of TDRs in accrual status, are applied to principal. Impaired LHFI, or portions thereof, are charged off when deemed uncollectible. Troubled Debt Restructuring A TDR occurs when a borrower is experiencing financial difficulties, and for related economic or legal reasons, a concession is granted to the borrower that Trustmark would not otherwise consider. Whatever the form of concession that might be granted by Trustmark, Management’s objective is to enhance collectibility by obtaining more cash or other value from the borrower or by increasing the probability of receipt by granting the concession than by not granting it. Other concessions may arise from court proceedings or may be imposed by law. In addition, TDRs also include those credits that are extended or renewed to a borrower who is not able to obtain funds from sources other than Trustmark at a market interest rate for new debt with similar risk. A formal TDR may include, but is not necessarily limited to, one or a combination of the following situations: • Trustmark accepts a third-party receivable or other asset(s) of the borrower, in lieu of the receivable from the borrower. • Trustmark accepts an equity interest in the borrower in lieu of the receivable. • Trustmark accepts modification of the terms of the debt including but not limited to: o Reduction (absolute or contingent) of the stated interest rate to below the current market rate. o Extension of the maturity date or dates at a stated interest rate lower than the current market rate for new debt with similar risk. o Reduction (absolute or contingent) of the face amount or maturity amount of the debt as stated in the note or other agreement. o Reduction (absolute or contingent) of accrued interest. Troubled debt restructurings are addressed in Trustmark’s loan policy, and in accordance with that policy, any modifications or concessions that may result in a TDR are subject to a special approval process which allows for control, identification, and monitoring of these arrangements. Prior to granting a concession, a revised borrowing arrangement is proposed which is structured so as to improve collectability of the loan in accordance with a reasonable repayment schedule with any loss promptly identified. It is supported by a thorough evaluation of the borrower’s financial condition and prospects for repayment under those revised terms. Other TDRs arising from renewals or extensions of existing debt are routinely identified through the processes utilized in the Problem Loan Committee and in the Credit Quality Review Committee. TDRs are subsequently reported to the Directors’ Credit Policy Committee on a quarterly basis and are disclosed in Trustmark’s consolidated financial statements in accordance with GAAP and regulatory reporting guidance. All loans whose terms have been modified in a troubled debt restructuring are evaluated for impairment under FASB ASC Topic 310, “Receivables.” Accordingly, Trustmark measures any loss on the restructuring in accordance with that guidance. A TDR in which Trustmark receives physical possession of the borrower’s assets, regardless of whether formal foreclosure or repossession proceedings take place, is accounted for in accordance with FASB ASC Subtopic 310-40. Thus, the loan is treated as if assets have been received in satisfaction of the loan and reported as a foreclosed asset. A TDR may be returned to accrual status if Trustmark is reasonably assured of repayment of principal and interest under the modified terms and the borrower has demonstrated sustained performance under those terms for a period of at least six months. Otherwise, the restructured loan must remain on nonaccrual. Allowance for Loan Losses, LHFI The allowance for loan losses, LHFI is established through provisions for estimated loan losses charged against net income. The allowance account is maintained at a level which is believed to be adequate by Management based on estimated probable losses within the LHFI portfolio. Evaluations of the portfolio and individual credits are inherently subjective, as they require estimates, assumptions and judgments as to the facts and circumstances of particular situations. Some of the factors considered, such as amounts and timing of future cash flows expected to be received, may be susceptible to significant change. Trustmark’s allowance methodology is based on guidance provided in Securities and Exchange Commission (SEC) Staff Accounting Bulletin (SAB) No. 102, “Selected Loan Loss Allowance Methodology and Documentation Issues,” as well as other regulatory guidance. The allowance for loan losses, LHFI consists of three components: (i) a historical valuation allowance determined in accordance with FASB ASC Topic 450, “Contingencies,” based on historical loan loss experience for LHFI with similar characteristics and trends, (ii) a specific valuation allowance determined in accordance with FASB ASC Topic 310 based on probable losses on specific LHFI and (iii) a qualitative risk valuation allowance determined in accordance with FASB ASC Topic 450 based on general economic conditions and other specific internal and external qualitative risk factors. Each of these components calls for estimates, assumptions and judgments as described below. Historical Valuation Allowance The historical valuation allowance is derived by application of a historical net loss percentage to the outstanding balances of LHFI contained in designated pools and risk rating categories. Pools are established by grouping credits that display similar characteristics and trends such as commercial LHFI for working capital purposes and non-working capital purposes, commercial purpose LHFI secured by real estate (which are further segregated into 1-4 family construction, non 1-4 family construction, land, lots and development, owner-occupied and nonowner - occupied categories), other commercial loans, 1-4 family LHFI, 1-4 family LHFI secured by junior liens and other consumer LHFI. Within these pools, LHFI are further segregated based on Trustmark’s internal credit risk rating process that evaluates, among other things: the obligor’s ability and willingness to pay, the value of underlying collateral, the ability of guarantors to meet their payment obligations, management experience and effectiveness, and the economic environment and industry in which the borrower operates. The historical net loss percentages, calculated on a quarterly basis, are proportionally distributed to each risk rate within loan groups based upon degree of risk. Using third-party default data, which is updated annually to incorporate the most recent year’s information, average cumulative issuer-weighted global default rates by alphanumeric rating are aggregated by Trustmark’s commercial loan risk rates. Management uses the long-term default rates to measure the relative risk across the risk rates while the 12-quarter quantitative loss rate sets the absolute level of allowance for loan loss reserve. Further, given the volatility in the default data, the longer look-back period provides for a more stable allowance for loan loss estimate which better reflects the incremental risk across the risk rates. The historical net loss percentages are calculated using a 12 quarter look-back period, which is the period that best reflects losses inherent in the current loan portfolio. The look-back period sufficiently captures the volatility in net charge-off rates from quarter to quarter and affects the qualitative adjustments that are required to capture the differences in conditions between the current period and those that were prevailing during the look-back period. The loss emergence period (LEP) refers to the period of time between the events that trigger a loss and charge-off of that loss. Losses are usually not immediately known and determining the loss event can be difficult. It takes time for the borrower and extent of loss to be identified and determined. Management may not be aware that the loss event has occurred until the borrower exhibits the inability to pay or other evidence of credit deterioration. The LEP is evaluated annually to incorporate the most recent year’s data and adjusted as necessary. Loans-Specific Valuation Allowance Once a LHFI is classified, it is subject to periodic review to determine whether or not the loan is impaired. If determined to be impaired, the loan is evaluated using one of the valuation criteria contained in FASB ASC Topic 310 (i.e., individually or collectively evaluated), and a specific valuation allowance is allocated, if necessary, so that the loan is reported at the net realizable value. Qualitative Risk Valuation Allowance The qualitative risk valuation allowance is based on general economic conditions and other internal and external factors affecting Trustmark as a whole as well as specific LHFI. Factors considered include the following within Trustmark’s five key market regions: the experience, ability, and effectiveness of Trustmark’s lending management and staff; adherence to Trustmark’s loans policies, procedures and internal controls; the volume of exceptions relating to collateral, underwriting and financial documentation; credit concentrations; recent performance trends; regional economic trends; the impact of recent acquisitions; and the impact of significant natural disasters. These factors are evaluated on a quarterly basis with the results representing Trustmark’s qualitative risk profile in the current period which is used to establish an appropriate allowance. The qualitative portion of the commercial and consumer LHFI allowance for loan loss methodology also incorporates the use of maximum observed gross historical losses observed through the last economic cycle as a way to calculate a maximum qualitative reserve limit. The maximum observed gross historical losses as a percentage of the loan balances results in a maximum observed gross historical loss rate. Once the quantitative component of the allowance for loan loss methodology is calculated, the quantitative reserve percentage is deducted from the maximum observed gross historical loss rate to determine the maximum possible qualitative reserve limit. Management uses its qualitative factor evaluation process in conjunction with this maximum to determine the appropriate estimate of the qualitative considerations not captured by Trustmark’s historical loss rates. Other factors included in the qualitative risk valuation allowance include consideration of: commercial loan facility risk that embodies the nature, frequency and duration of the repayment structure as it pertains to the actual source of loan repayment, commercial nonaccrual relationships under $500 thousand which are below the threshold to perform a specific impairment analysis, and independent consumer credit bureau scores that are monitored to identify shifts in risk that are represented in the retail portfolio. These factors are also evaluated on a quarterly basis with the exception of the commercial nonaccrual relationships under $500 thousand which are evaluated monthly. and credit card debt are generally charged off on or prior to 180 days of delinquency. LHFI are charged off against the allowance for loan losses, LHFI, with any subsequent recoveries credited back to the allowance account. Acquired Loans Acquired loans are accounted for under the acquisition method of accounting. The acquired loans are recorded at their estimated fair value at the time of acquisition. The fair value of acquired loans is determined using a discounted cash flow model based on assumptions regarding the amount and timing of principal and interest payments, estimated prepayments, estimated default rates, estimated loss severity in the event of defaults and current market rates. Estimated credit losses are included in the determination of fair value; therefore, an allowance for loan losses is not recorded on the acquisition date. Trustmark accounts for acquired impaired loans under FASB ASC Subtopic 310-30, “Loans and Debt Securities Acquired with Deteriorated Credit Quality.” An acquired loan is considered impaired when there is evidence of credit deterioration since origination and it is probable at the date of acquisition that Trustmark would be unable to collect all contractually required payments. Acquired loans accounted for under FASB ASC Subtopic 310-30 are referred to as “acquired impaired loans.” Revolving credit agreements, such as home equity lines, and commercial leases are excluded from acquired impaired loan accounting requirements. For acquired impaired loans, Trustmark (i) calculates the contractual amount and timing of undiscounted principal and interest payments (the “undiscounted contractual cash flows”) and (ii) estimates the amount and timing of undiscounted expected principal and interest payments (the “undiscounted expected cash flows”). Under FASB ASC Subtopic 310-30, the difference between the undiscounted contractual cash flows and the undiscounted expected cash flows is the nonaccretable difference. The nonaccretable difference represents an estimate of the loss exposure of principal and interest related to the acquired impaired loan portfolio, and such amount is subject to change over time based on the performance of such loans. The excess of undiscounted expected cash flows at acquisition over the initial fair value of acquired impaired loans is referred to as the “accretable yield” and is recorded as interest income over the estimated life of the loans using the effective yield method if the timing and amount of the future cash flows is reasonably estimable. Under the effective yield method, the accretable yield is recorded as an accretion of interest income over the life of the loan. Trustmark aggregates certain acquired impaired loans into pools of loans with common credit risk characteristics such as loan type and risk rating. To establish accounting pools of acquired impaired loans, loans are first categorized by similar purpose, collateral and geographic region. Within each category, the acquired impaired loans are further segmented by ranges of risk determinants observed at the time of acquisition. For commercial loans, the primary risk determinant is the risk rating as assigned by Trustmark. For consumer loans, the risk determinants include delinquency, delinquency history and FICO scores. Statistical comparison of the pools reflect that each pool is comprised of acquired impaired loans generally of similar characteristics, including loan type, loan risk and weighted average life. Each pool is then reviewed for similarity of the pool constituents, including standard deviation of purchase price, weighted average life and concentration of the largest loans. Loan pools are initially booked at the aggregate fair value of the loan pool constituents, based on the present value of Trustmark's expected cash flows from the acquired impaired loans. An acquired impaired loan is removed from a pool of loans only if the loan is sold, foreclosed, payment is received in full satisfaction of the loan or the loan is fully charged off. The acquired impaired loan is removed from the pool at the carrying value. When an individual acquired impaired loan is removed from a pool of loans, the difference between its relative carrying amount and the cash, collateral (measured at fair value) or other assets received will be recognized as a gain or loss immediately in interest income on acquired loans and would not affect the effective yield used to recognize the accretable yield on the remaining pool. Certain acquired impaired loans are not pooled and are accounted for individually. Such acquired impaired loans are withheld from pools due to the inherent uncertainty of the timing and amount of their cash flows or because they are not a suitable similar constituent to the established pools. As required by FASB ASC Subtopic 310-30, Trustmark periodically re-estimates the expected cash flows to be collected over the life of the acquired impaired loans. If, based on current information and events, it is probable that Trustmark will be unable to collect all cash flows expected at acquisition plus additional cash flows expected to be collected arising from changes in estimate after acquisition, the acquired loans are considered impaired. The decrease in the expected cash flows reduces the carrying value of the acquired impaired loans as well as the accretable yield and results in a charge-off through the allowance for loan losses, acquired loans or the establishment of an allowance for loan losses, acquired loans with a charge to income through the provision for loan losses, acquired loans. If, based on current information and events, it is probable that there is a significant increase in the cash flows previously expected to be collected or if actual cash flows are significantly greater than cash flows previously expected, Trustmark will reduce any remaining allowance for loan losses, acquired loans established on the acquired impaired loans for the increase in the present value of cash flows expected to be collected. The increase in the expected cash flows for the acquired impaired loans over those originally estimated at acquisition increases the carrying value of the acquired impaired loans as well as the accretable yield. The increase in the accretable yield is recognized as interest income prospectively over the remaining life of the acquired impaired loans. The carrying value of acquired impaired loans is reduced by payments received, both principal and interest, and increased by the portion of the accretable yield recognized as interest income. Under FASB ASC Subt opic 310-30, acquired impaired loans are generally considered accruing and performing loans as the loans accrete interest income over the estimated life of the loan when expected cash flows are reasonably estimable. Accordingly, acquired impaired loans that are contractually past due are still considered to be accruing and performing loans as long as the estimated cash flows are received as expected. If the timing and amount of cash flows is not reasonably estimable, the loans may be classified as nonaccrual loans and interest income may be recognized on a cash basis or as a reduction of the principal amount outstanding. Premises and Equipment, Net Premises and equipment are reported at cost, less accumulated depreciation and amortization. Depreciation is charged to expense over the estimated useful lives of the assets, which are up to thirty-nine years for buildings and three to ten years for furniture and equipment. Leasehold improvements are amortized over the terms of the respective leases or the estimated useful lives of the improvements, whichever is shorter. In cases where Trustmark has the right to renew the lease for additional periods, the lease term for the purpose of calculating amortization of the capitalized cost of the leasehold improvements is extended when Trustmark is “reasonably assured” that it will renew the lease. Depreciation and amortization expenses are computed using the straight-line method. Trustmark continually evaluates whether events and circumstances have occurred that indicate that such long-lived assets have become impaired. Measurement of any impairment of such long-lived assets is based on the fair values of those assets. Branch closures and purchased land held for future branch expansion for more than five years are evaluated to determine if the related land, buildings and building improvements should be transferred to assets held for sale in accordance with FASB ASC Topic 360, “Property, Plant and Equipment.” The property is transferred to assets held for sale at the lower of its carrying value or fair value less cost to sell. An impairment loss is recorded at the time of transfer if the carrying value of the assets exceeds the fair value. Impairment losses are recorded as non-interest expense in other expense. Mortgage Servicing Rights (MSR) Trustmark recognizes as assets the rights to service mortgage loans based on the estimated fair value of the MSR when loans are sold and the associated servicing rights are retained. Trustmark has elected to account for the MSR at fair value. The fair value of the MSR is determined using discounted cash flow techniques benchmarked against third-party valuations. Estimates of fair value involve several assumptions, including the key valuation assumptions about market expectations of future prepayment rates, interest rates and discount rates which are provided by a third-party firm. Prepayment rates are projected using an industry standard prepayment model. The model considers other key factors, such as a wide range of standard industry assumptions tied to specific portfolio characteristics such as remittance cycles, escrow payment requirements, geographic factors, foreclosure loss exposure, VA no-bid exposure, delinquency rates and cost of servicing, including base cost and cost to service delinquent mortgages. Prevailing market conditions at the time of analysis are factored into the accumulation of assumptions and determination of servicing value. Trustmark economically hedges changes in the fair value of the MSR attributable to interest rates. See Note 1 – Significant Accounting Policies, “Derivative Financial Instruments – Derivatives Not Designated as Hedging Instruments” for information regarding these derivative instruments. Trustmark receives annual servicing fee income for loans serviced, which is recorded as noninterest income in mortgage banking, net. The fees are based on a contractual percentage of the outstanding principal or a f

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Business Combinations	Note 2 – Business Combinations On April 7, 2017, Trustmark completed its merger with RB Bancorporation (Reliance), the holding company for Reliance Bank, which had seven offices serving the Huntsville, Alabama metropolitan service area (MSA). Reliance Bank was merged into Trustmark National Bank simultaneously with the merger of Trustmark and Reliance. Under the terms of the Merger Agreement dated November 14, 2016, Trustmark paid $22.00 in cash for each share of Reliance common stock outstanding, which represented payment to Reliance common shareholders of approximately $23.7 million. In addition, Trustmark paid off Reliance Preferred Stock of $1.1 million bringing the total consideration paid to $24.8 million. The merger with Reliance was consistent with Trustmark’s strategic plan to selectively expand the Trustmark franchise and enhance the Trustmark franchise in north Alabama. This merger was accounted for in accordance with FASB ASC Topic 805, “Business Combinations.” Accordingly, the assets and liabilities, both tangible and intangible, were recorded at their estimated fair values as of the merger date. The statement of assets purchased and liabilities assumed in the Reliance merger is presented below at their estimated fair values as of the merger date of April 7, 2017 ($ in thousands): Assets: Cash and due from banks $ 5,013 Federal funds sold and securities purchased under reverse repurchase agreements 6,900 Securities 54,843 Acquired loans 117,447 Premises and equipment, net 3,700 Identifiable intangible assets 1,850 Other real estate 475 Other assets 6,037 Total Assets 196,265 Liabilities: Deposits 166,158 Other borrowings 17,469 Other liabilities 1,322 Total Liabilities 184,949 Net identified assets acquired at fair value 11,316 Goodwill 13,471 Total consideration paid $ 24,787 The excess of the consideration paid over the estimated fair value of the net assets acquired was $13.5 million, which was recorded as goodwill under FASB ASC Topic 805. The identifiable intangible assets acquired represent the core deposit intangible at fair value at the merger date. The core deposit intangible is being amortized on an accelerated basis over the estimated useful life, currently expected to be approximately ten years. Loans acquired from Reliance were evaluated under a fair value process. Loans with evidence of deterioration in credit quality and for which it was probable at acquisition that Trustmark would not be able to collect all contractually required payments are referred to as acquired impaired loans and accounted for in accordance with FASB ASC Subtopic 310-30. See Note 6 – Acquired Loans for additional information on acquired loans. The operations of Reliance are included in Trustmark’s operating results from April 7, 2017 and did not have a material impact on Trustmark’s results of operations. During the second quarter of 2017, Trustmark included merger transaction expenses in other noninterest expense totaling $3.2 million (change in control expense of $1.3 million; professional fees, contract termination and other expenses of $1.9 million). Fair Value of Acquired Financial Instruments For financial instruments measured at fair value, Trustmark utilized inputs within Level 2 of the fair value hierarchy to determine the fair value of securities available for sale (included in securities above), time deposits (included in deposits above) and FHLB advances (included in other borrowings above). Level 3 inputs were used to determine the fair value of acquired loans, identifiable intangible assets and other real estate. The methodology and significant assumptions used in estimating the fair values of these financial assets and liabilities are as follows: Securities Available for Sale Estimated fair values for securities available for sale are based on quoted market prices where available. If quoted market prices are not available, estimated fair values are based on quoted market prices of comparable instruments. Acquired Loans Fair value of acquired loans is determined using a discounted cash flow model based on assumptions regarding the amount and timing of principal and interest payments, estimated prepayments, estimated default rates, estimated loss severity in the event of default and current market rates. Identifiable Intangible Assets The fair value assigned to the identifiable intangible assets, in this case the core deposit intangible, represents the future economic benefits of the potential cost savings from acquiring core deposits in the merger compared to the cost of obtaining alternative funding from market sources. Other Real Estate Other real estate was initially recorded at its estimated fair value on the merger date based on independent appraisals less estimated selling costs. Time Deposits Time deposits were valued by projecting expected cash flows into the future based on each account’s contracted rate and then determining the present value of those expected cash flows using current rates for deposits with similar maturities. FHLB Advances FHLB advances were valued by projecting expected cash flows into the future based on each advance’s contracted rate and then determining the present value of those expected cash flows using current rates for advances with similar maturities. Please refer to Note 20 – Fair Value for more information on Trustmark’s classification of financial instruments based on valuation inputs within the fair value hierarchy.

Cash and Due from Banks

Cash and Due from Banks	12 Months Ended
	Dec. 31, 2019
Cash And Cash Equivalents [Abstract]
Cash and Due from Banks	Note 3 – Cash and Due from Banks Trustmark is required to maintain average reserve balances with the Federal Reserve Bank of Atlanta based on a percentage of deposits. The average amounts of those reserves for the years ended December 31, 2019 and 2018 were $122.4 million and $112.4 million, respectively.

Securities Available for Sale a

Securities Available for Sale and Held to Maturity	12 Months Ended
	Dec. 31, 2019
Investments Debt And Equity Securities [Abstract]
Securities Available for Sale and Held to Maturity	Note 4 – Securities Available for Sale and Held to Maturity The following tables are a summary of the amortized cost and estimated fair value of securities available for sale and held to maturity at December 31, 2019 and 2018 ($ in thousands): Securities Available for Sale Securities Held to Maturity Gross Gross Estimated Gross Gross Estimated Amortized Unrealized Unrealized Fair Amortized Unrealized Unrealized Fair December 31, 2019 Cost Gains Losses Value Cost Gains Losses Value U.S. Government agency obligations $ 22,965 $ 69 $ (707 ) $ 22,327 $ 3,781 $ 220 $ — $ 4,001 Obligations of states and political subdivisions 24,952 513 — 25,465 31,781 434 (53 ) 32,162 Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 69,196 425 (369 ) 69,252 10,820 266 (10 ) 11,076 Issued by FNMA and FHLMC 714,350 2,171 (3,165 ) 713,356 96,631 286 (370 ) 96,547 Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 656,162 3,777 (1,713 ) 658,226 485,324 7,026 (656 ) 491,694 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 113,359 625 (206 ) 113,778 109,762 1,042 (82 ) 110,722 Total $ 1,600,984 $ 7,580 $ (6,160 ) $ 1,602,404 $ 738,099 $ 9,274 $ (1,171 ) $ 746,202 December 31, 2018 U.S. Government agency obligations $ 31,235 $ 109 $ (1,009 ) $ 30,335 $ 3,736 $ 78 $ — $ 3,814 Obligations of states and political subdivisions 50,503 200 (27 ) 50,676 35,783 255 (139 ) 35,899 Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 69,648 147 (2,301 ) 67,494 12,090 45 (257 ) 11,878 Issued by FNMA and FHLMC 685,520 127 (18,963 ) 666,684 115,133 43 (2,887 ) 112,289 Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 830,129 67 (18,595 ) 811,601 578,827 189 (15,441 ) 563,575 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 187,494 191 (2,662 ) 185,023 164,074 299 (2,095 ) 162,278 Total $ 1,854,529 $ 841 $ (43,557 ) $ 1,811,813 $ 909,643 $ 909 $ (20,819 ) $ 889,733 During 2013, Trustmark reclassified approximately $1.099 billion of securities available for sale to securities held to maturity. The securities were transferred at fair value, which became the cost basis for the securities held to maturity. At the date of transfer, the net unrealized holding loss on the available for sale securities totaled approximately $46.6 million ($28.8 million, net of tax). The net unrealized holding loss is amortized over the remaining life of the securities as a yield adjustment in a manner consistent with the amortization or accretion of the original purchase premium or discount on the associated security. There were no gains or losses recognized as a result of the transfer. At December 31, 2019 and 2018, the net unamortized, unrealized loss on the transferred securities included in accumulated other comprehensive loss in the accompanying balance sheet totaled approximately $12.1 million ($9.1 million, net of tax) and $15.7 million ($11.8 million, net of tax), respectively. Temporarily Impaired Securities The table below includes securities with gross unrealized losses segregated by length of impairment at December 31, 2019 and 2018 ($ in thousands): Less than 12 Months 12 Months or More Total Gross Gross Gross Estimated Unrealized Estimated Unrealized Estimated Unrealized December 31, 2019 Fair Value Losses Fair Value Losses Fair Value Losses U.S. Government agency obligations $ 6,585 $ (105 ) $ 12,886 $ (602 ) $ 19,471 $ (707 ) Obligations of states and political subdivisions — — 6,216 (53 ) 6,216 (53 ) Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 23,544 (107 ) 18,529 (272 ) 42,073 (379 ) Issued by FNMA and FHLMC 112,879 (230 ) 278,120 (3,305 ) 390,999 (3,535 ) Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 158,341 (738 ) 151,271 (1,631 ) 309,612 (2,369 ) Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 51,312 (167 ) 14,155 (121 ) 65,467 (288 ) Total $ 352,661 $ (1,347 ) $ 481,177 $ (5,984 ) $ 833,838 $ (7,331 ) December 31, 2018 U.S. Government agency obligations $ — $ — $ 25,045 $ (1,009 ) $ 25,045 $ (1,009 ) Obligations of states and political subdivisions 4,954 (9 ) 12,802 (157 ) 17,756 (166 ) Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 9,163 (54 ) 61,141 (2,504 ) 70,304 (2,558 ) Issued by FNMA and FHLMC 31,931 (172 ) 731,749 (21,678 ) 763,680 (21,850 ) Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 46,643 (110 ) 1,296,221 (33,926 ) 1,342,864 (34,036 ) Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 5,497 (37 ) 272,789 (4,720 ) 278,286 (4,757 ) Total $ 98,188 $ (382 ) $ 2,399,747 $ (63,994 ) $ 2,497,935 $ (64,376 ) The unrealized losses shown above are due to increases in market rates over the yields available at the time of purchase of the underlying securities and not credit quality. Because Trustmark does not intend to sell these securities and it is more likely than not that Trustmark will not be required to sell the investments before recovery of their amortized cost bases, which may be maturity, Trustmark does not consider these investments to be other-than-temporarily impaired at December 31, 2019. There were no other-than-temporary impairments for the years ended December 31, 2019, 2018 and 2017. Security Gains and Losses For the periods presented, gross realized gains or losses as a result of calls and dispositions of securities, as well as any associated proceeds, were as follows ($ in thousands): Years Ended December 31, Available for Sale 2019 2018 2017 Proceeds from calls and sales of securities $ — $ — $ 27,682 Gross realized gains — — 16 Gross realized losses — — (1 ) Securities Pledged Securities with a carrying value of $1.770 billion and $2.144 billion at December 31, 2019 and 2018, respectively, were pledged to collateralize public deposits and securities sold under repurchase agreements and for other purposes as permitted by law. At both December 31, 2019 and 2018, none of these securities were pledged under the Federal Reserve Discount Window program to provide additional contingency funding capacity. Contractual Maturities The amortized cost and estimated fair value of securities available for sale and held to maturity at December 31, 2019, by contractual maturity, are shown below ($ in thousands). Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Securities Securities Available for Sale Held to Maturity Amortized Estimated Amortized Estimated Cost Fair Value Cost Fair Value Due in one year or less $ 22,480 $ 22,623 $ 5,071 $ 5,115 Due after one year through five years 1,598 1,614 30,491 31,048 Due after five years through ten years 2,561 2,513 — — Due after ten years 21,278 21,042 — — 47,917 47,792 35,562 36,163 Mortgage-backed securities 1,553,067 1,554,612 702,537 710,039 Total $ 1,600,984 $ 1,602,404 $ 738,099 $ 746,202

Loans Held for Investment (LHFI

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI	12 Months Ended
	Dec. 31, 2019
Accounts Notes Loans And Financing Receivable Gross Allowance And Net [Abstract]
Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI	Note 5 – LHFI and Allowance for Loan Losses, LHFI At December 31, 2019 and 2018, LHFI consisted of the following ($ in thousands): December 31, 2019 2018 Loans secured by real estate: Construction, land development and other land $ 1,162,791 $ 1,056,601 Secured by 1-4 family residential properties 1,855,913 1,825,492 Secured by nonfarm, nonresidential properties 2,475,245 2,220,914 Other real estate secured 724,480 543,820 Commercial and industrial loans 1,477,896 1,538,715 Consumer loans 175,738 182,448 State and other political subdivision loans 967,944 973,818 Other loans 495,621 494,060 LHFI 9,335,628 8,835,868 Less allowance for loan losses, LHFI 84,277 79,290 Net LHFI $ 9,251,351 $ 8,756,578 Loan Concentrations Trustmark does not have any loan concentrations other than those reflected in the preceding table, which exceed 10% of total LHFI. At December 31, 2019, Trustmark’s geographic loan distribution was concentrated primarily in its five key market regions: Alabama, Florida, Mississippi, Tennessee and Texas. Accordingly, the ultimate collectability of a substantial portion of these loans is susceptible to changes in market conditions in these areas. Related Party Loans At December 31, 2019 and 2018, loans to certain executive officers and directors, including their immediate families and companies in which they are principal owners, totaled $35.5 million and $49.0 million, respectively. During 2019, $464.6 million of new loan advances were made, while repayments were $478.1 million. There were no increases in loans due to changes in executive officers and directors. Nonaccrual and Past Due LHFI No material interest income was recognized in the income statement on nonaccrual LHFI for each of the years in the three-year period ended December 31, 2019. The following tables provide an aging analysis of past due and nonaccrual LHFI by loan type at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Past Due 90 Days Current 30-59 Days 60-89 Days or More (1) Total Nonaccrual Loans Total Loans secured by real estate: Construction, land development and other land $ 380 $ 256 $ — $ 636 $ 897 $ 1,161,258 $ 1,162,791 Secured by 1-4 family residential properties 5,254 940 211 6,405 16,810 1,832,698 1,855,913 Secured by nonfarm, nonresidential properties 1,698 — — 1,698 7,700 2,465,847 2,475,245 Other real estate secured 8 — — 8 1,032 723,440 724,480 Commercial and industrial loans 617 12 39 668 21,775 1,455,453 1,477,896 Consumer loans 2,208 380 392 2,980 108 172,650 175,738 State and other political subdivision loans 76 — — 76 4,079 963,789 967,944 Other loans 152 4 — 156 825 494,640 495,621 Total $ 10,393 $ 1,592 $ 642 $ 12,627 $ 53,226 $ 9,269,775 $ 9,335,628 (1) Past due 90 days or more but still accruing interest. December 31, 2018 Past Due 90 Days Current 30-59 Days 60-89 Days or More (1) Total Nonaccrual Loans Total Loans secured by real estate: Construction, land development and other land $ 284 $ — $ — $ 284 $ 2,218 $ 1,054,099 $ 1,056,601 Secured by 1-4 family residential properties 8,600 1,700 569 10,869 14,718 1,799,905 1,825,492 Secured by nonfarm, nonresidential properties 1,887 — — 1,887 9,621 2,209,406 2,220,914 Other real estate secured 197 99 — 296 927 542,597 543,820 Commercial and industrial loans 1,346 300 — 1,646 23,938 1,513,131 1,538,715 Consumer loans 1,800 353 287 2,440 205 179,803 182,448 State and other political subdivision loans 186 — — 186 8,595 965,037 973,818 Other loans 83 — — 83 1,402 492,575 494,060 Total $ 14,383 $ 2,452 $ 856 $ 17,691 $ 61,624 $ 8,756,553 $ 8,835,868 (1) Past due 90 days or more but still accruing interest. Impaired LHFI Trustmark’s individually evaluated impaired LHFI include all commercial nonaccrual relationships of $500 thousand or more, which are specifically reviewed for impairment and deemed impaired, and all LHFI classified as TDRs in accordance with FASB ASC Subtopic 310-10-50-20 “Impaired Loans,” and are primarily collateral dependent loans. Fair value estimates for collateral dependent loans are derived from appraised values based on the current market value or as is value of the collateral, normally from recently received and reviewed appraisals. Current appraisals are ordered on an annual basis based on the inspection date or more often if market conditions necessitate. Appraisals are obtained from state-certified appraisers and are based on certain assumptions, which may include construction or development status and the highest and best use of the property. These appraisals are reviewed by Trustmark’s Appraisal Review Department to ensure they are acceptable, and values are adjusted down for costs associated with asset disposal. Once this estimated net realizable value has been determined, the value used in the impairment assessment is updated. At the time a LHFI that has been specifically reviewed for impairment is deemed to be impaired, the full difference between book value and the most likely estimate of the collateral’s net realizable value is charged off or a specific reserve is established. As subsequent events dictate and estimated net realizable values change, further adjustments may be necessary. No material interest income was recognized in the accompanying consolidated statements of income on impaired LHFI for each of the years in the three-year period ended December 31, 2019. At December 31, 2019 and 2018, individually evaluated for impaired LHFI consisted of the following ($ in thousands): December 31, 2019 LHFI Unpaid Wit h o With an Total Average Principal Allowance Allowance Carrying Related Recorded Balance Recorded Recorded Amount Allowance Investment Loans secured by real estate: Construction, land development and other land $ 926 $ 610 $ 16 $ 626 $ — $ 1,089 Secured by 1-4 family residential properties 6,513 2,104 3,360 5,464 35 4,713 Secured by nonfarm, nonresidential properties 7,295 1,462 5,255 6,717 2,355 8,096 Other real estate secured 69 — 68 68 — 158 Commercial and industrial loans 27,178 19,374 4,084 23,458 707 27,088 Consumer loans 22 — 21 21 — 11 State and other political subdivision loans 4,079 — 4,079 4,079 1,809 6,337 Other loans 1,207 — 784 784 553 1,033 Total $ 47,289 $ 23,550 $ 17,667 $ 41,217 $ 5,459 $ 48,525 December 31, 2018 LHFI Unpaid Wit h o With an Total Average Principal Allowance Allowance Carrying Related Recorded Balance Recorded Recorded Amount Allowance Investment Loans secured by real estate: Construction, land development and other land $ 1,794 $ 1,528 $ 24 $ 1,552 $ — $ 1,738 Secured by 1-4 family residential properties 4,951 95 3,868 3,963 39 4,328 Secured by nonfarm, nonresidential properties 8,282 6,728 2,748 9,476 413 8,898 Other real estate secured — — 248 248 — 124 Commercial and industrial loans 37,786 12,893 17,824 30,717 4,334 26,725 Consumer loans 2 — 2 2 — 6 State and other political subdivision loans 8,688 4,079 4,516 8,595 516 4,297 Other loans 1,418 230 1,052 1,282 1,052 804 Total $ 62,921 $ 25,553 $ 30,282 $ 55,835 $ 6,354 $ 46,920 Troubled Debt Restructurings At December 31, 2019, 2018 and 2017, LHFI classified as TDRs totaled $31.5 million, $28.2 million and $23.9 million, respectively, and were primarily comprised of credits with interest-only payments for an extended period of time and credits renewed at a rate that was not commensurate with that of new debt with similar risk which totaled $20.8 million, $23.8 million and $20.5 million, respectively. The remaining TDRs at December 31, 2019, 2018 and 2017 resulted from bankruptcies or from payment or maturity extensions. Trustmark had $7.0 million of unused commitments on TDRs at December 31, 2019, compared to $4.4 million of unused commitments on TDRs at December 31, 2018 and no material unused commitments on TDRs at December 31, 2017. For TDRs, Trustmark had a related loan loss allowance of $3.2 million at December 31, 2019, $2.3 million at December 31, 2018 and $458 thousand at December 31, 2017. LHFI classified as TDRs are charged down to the most likely fair value estimate less an estimated cost to sell for collateral dependent loans, which would approximate net realizable value. Specific charge-offs related to TDRs totaled $1.6 million, $18.4 million and $127 thousand for the years ended December 31, 2019, 2018 and 2017, respectively. The following tables illustrate the impact of modifications classified as TDRs for the periods presented ($ in thousands): Year Ended December 31, 2019 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Secured by 1-4 family residential properties 19 $ 1,742 $ 1,738 Secured by nonfarm, nonresidential properties 1 5,055 5,055 Commercial and industrial loans 8 9,167 9,054 Consumer loans 2 30 30 Total 30 $ 15,994 $ 15,877 Year Ended December 31, 2018 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Construction, land development and other land 1 $ 22 $ 22 Secured by 1-4 family residential properties 23 2,102 1,660 Secured by nonfarm, nonresidential properties 2 1,780 1,780 Commercial and industrial loans 23 26,970 25,862 Consumer loans 3 4 4 Total 52 $ 30,878 $ 29,328 Year Ended December 31, 2017 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Construction, land development and other land 1 $ 341 $ 325 Secured by 1-4 family residential properties 22 1,478 1,487 Secured by nonfarm, nonresidential properties 1 426 426 Commercial and industrial loans 8 12,836 12,836 Other loans 1 556 556 Total 33 $ 15,637 $ 15,630 The table below includes the balances at default for TDRs modified within the last 12 months for which there was a payment default during the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 TDRs that Subsequently Defaulted Number of Contracts Recorded Investment Number of Contracts Recorded Investment Number of Contracts Recorded Investment Construction, land development and other land loans — $ — 1 $ 22 — $ — Loans secured by 1-4 family residential properties 3 446 5 734 4 78 Commercial and industrial loans 7 192 6 15,178 3 9,526 Consumer loans 1 27 1 1 — — Total 11 $ 665 13 $ 15,935 7 $ 9,604 Trustmark’s TDRs have resulted primarily from allowing the borrower to pay interest-only for an extended period of time and credits renewed at a rate that was not commensurate with that of new debt with similar risk rather than from forgiveness. Accordingly, as shown above, these TDRs have a similar recorded investment for both the pre-modification and post-modification disclosure. Trustmark has utilized loans 90 days or more past due to define payment default in determining TDRs that have subsequently defaulted . The following tables detail LHFI classified as TDRs by loan type at December 31, 2019, 2018 and 2017 ($ in thousands): December 31, 2019 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 15 $ 15 Secured by 1-4 family residential properties 77 3,865 3,942 Secured by nonfarm, nonresidential properties — 5,176 5,176 Commercial and industrial loans 3,319 18,913 22,232 Consumer loans — 21 21 Other loans — 137 137 Total TDRs $ 3,396 $ 28,127 $ 31,523 December 31, 2018 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 24 $ 24 Secured by 1-4 family residential properties 743 3,125 3,868 Secured by nonfarm, nonresidential properties 1,734 395 2,129 Commercial and industrial loans 9,007 12,620 21,627 Consumer loans — 2 2 Other loans — 540 540 Total TDRs $ 11,484 $ 16,706 $ 28,190 December 31, 2017 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 199 $ 199 Secured by 1-4 family residential properties 51 3,140 3,191 Secured by nonfarm, nonresidential properties — 421 421 Commercial and industrial loans 53 19,434 19,487 Consumer loans — 17 17 Other loans 556 — 556 Total TDRs $ 660 $ 23,211 $ 23,871 Credit Quality Indicators Trustmark’s loan portfolio credit quality indicators focus on six key quality ratios that are compared against bank tolerances. The loan indicators are total classified outstanding, total criticized outstanding, nonperforming loans, nonperforming assets, delinquencies and net loan losses. Due to the homogenous nature of consumer loans, Trustmark does not assign a formal internal risk rating to each credit and therefore the criticized and classified measures are primarily composed of commercial loans. In addition to monitoring portfolio credit quality indicators, Trustmark also measures how effectively the lending process is being managed and risks are being identified. As part of an ongoing monitoring process, Trustmark grades the commercial portfolio as it relates to credit file completion and financial statement exceptions, underwriting, collateral documentation and compliance with law as shown below: • Credit File Completeness and Financial Statement Exceptions – evaluates the quality and condition of credit files in terms of content and completeness and focuses on efforts to obtain and document sufficient information to determine the quality and status of credits. Also included is an evaluation of the systems/procedures used to insure compliance with policy. • Underwriting – evaluates whether credits are adequately analyzed, appropriately structured and properly approved within loan policy requirements. A properly approved credit is approved by adequate authority in a timely manner with all conditions of approval fulfilled. Total policy exceptions measure the level of underwriting and other policy exceptions within a loan portfolio. • Collateral Documentation – focuses on the adequacy of documentation to perfect Trustmark’s collateral position and substantiate collateral value. Collateral exceptions measure the level of documentation exceptions within a loan portfolio. Collateral exceptions occur when certain collateral documentation is either not present or not current. • Compliance with Law – focuses on underwriting, documentation, approval and reporting in compliance with banking laws and regulations. Primary emphasis is directed to the Financial Institutions Reform, Recovery and Enforcement Act of 1989 (FIRREA), Regulation O requirements and regulations governing appraisals. Commercial Credits Trustmark has established a loan grading system that consists of ten individual credit risk grades (risk ratings) that encompass a range from loans where the expectation of loss is negligible to loans where loss has been established. The model is based on the risk of default for an individual credit and establishes certain criteria to delineate the level of risk across the ten unique credit risk grades. Credit risk grade definitions are as follows: • Risk Rate (RR) 1 through RR 6 – Grades one through six represent groups of loans that are not subject to criticism as defined in regulatory guidance. Loans in these groups exhibit characteristics that represent low to moderate risk measured by using a variety of credit risk criteria such as cash flow coverage, debt service coverage, balance sheet leverage, liquidity, management experience, industry position, prevailing economic conditions, support from secondary sources of repayment and other credit factors that may be relevant to a specific loan. In general, these loans are supported by properly margined collateral and guarantees of principal parties. • Other Assets Especially Mentioned (Special Mention) - (RR 7) – a loan that has a potential weakness that if not corrected will lead to a more severe rating. This rating is for credits that are currently protected but potentially weak because of an adverse feature or condition that if not corrected will lead to a further downgrade. • Substandard (RR 8) – a loan that has at least one identified weakness that is well defined. This rating is for credits where the primary sources of repayment are not viable at the time of evaluation or where either the capital or collateral is not adequate to support the loan and the secondary means of repayment do not provide a sufficient level of support to offset the identified weakness. Loss potential exists in the aggregate amount of substandard loans but does not necessarily exist in individual loans. • Doubtful (RR 9) – a loan with an identified weakness that does not have a valid secondary source of repayment. Generally these credits have an impaired primary source of repayment and secondary sources are not sufficient to prevent a loss in the credit. The exact amount of the loss has not been determined at this time. • Loss (RR 10) – a loan or a portion of a loan that is deemed to be uncollectible. By definition, credit risk grades special mention (RR 7), substandard (RR 8), doubtful (RR 9) and loss (RR 10) are criticized loans while substandard (RR 8), doubtful (RR 9) and loss (RR 10) are classified loans. These definitions are standardized by all bank regulatory agencies and are generally equally applied to each individual lending institution. The remaining credit risk grades are considered pass credits and are solely defined by Trustmark. Each commercial loan is assigned a credit risk grade that is an indication for the likelihood of default and is not a direct indication of loss at default. The loss at default aspect of the subject risk ratings is neither uniform across the nine primary commercial loan groups or constant between the geographic areas. To account for the variance in the loss at default aspects of the risk rating system, the loss expectations for each risk rating are integrated into the allowance for loan loss methodology where the calculated loss at default is allotted for each individual risk rating with respect to the individual loan group and unique geographic area. The loss at default aspect of the reserve methodology is calculated each quarter as a component of the overall reserve factor for each risk grade by loan group and geographic area. To enhance this process, commercial nonaccrual relationships of $500 thousand or more are routinely reviewed to establish an expectation of loss, if any, and if such examination indicates that the level of reserve is not adequate to cover the expectation of loss, a special reserve or impairment is generally applied. The distribution of the losses is accomplished by means of a loss distribution model that assigns a loss factor to each risk rating (1 to 9) in each commercial loan pool. A factor is not applied to risk rate 10 as loans classified as losses are charged off within the period that the loss is determined and are not carried on Trustmark’s books over quarter-end. The expected loss distribution is spread across the various risk ratings by the perceived level of risk for loss. The nine grade scale described above ranges from a negligible risk of loss to an identified loss across its breadth. The loss distribution factors are graduated through the scale on a basis proportional to the degree of risk that appears manifest in each individual rating and assumes that migration through the loan grading system will occur. Each loan officer assesses the appropriateness of the internal risk rating assigned to their credits on an ongoing basis. Trustmark’s Asset Review area conducts independent credit quality reviews of the majority of Trustmark’s commercial loan portfolio both on the underlying credit quality of each individual loan portfolio as well as the adherence to Trustmark’s loan policy and the loan administration process. In general, Asset Review conducts reviews of each lending area within a six to eighteen month window depending on the overall credit quality results of the individual area. In addition to the ongoing internal risk rate monitoring described above, Trustmark’s Credit Quality Review Committee meets monthly and performs a review of all loans of $100 thousand or more that are either delinquent thirty days or more or on nonaccrual. This review includes recommendations regarding risk ratings, accrual status, charge-offs and appropriate servicing officer as well as evaluation of problem credits for determination of TDRs. Quarterly, the Credit Quality Review Committee reviews and modifies continuous action plans for all credits risk rated seven or worse for relationships of $100 thousand or more. In addition, a semi-annual review of significant development and commercial construction projects and an annual review of certain existing nonowner-occupied projects and multi-family projects is performed. The review assesses each particular project with respect to location, project valuations, progress of completion, leasing status, current financial information, rents, operating expenses, cash flow, adherence to budget and projections and other information as applicable. Summary results are reviewed by Senior and Regional Credit Officers in addition to the Chief Credit Officer with a determination as to the appropriateness of existing risk ratings and accrual status. Consumer Credits Consumer LHFI that do not meet a minimum custom credit score are reviewed quarterly by Management. The Retail Credit Review Committee reviews the volume and percentage of approvals that did not meet the minimum passing custom score by region, individual location, and officer to ensure that Trustmark continues to originate quality loans. Trustmark monitors the levels and severity of past due consumer LHFI on a daily basis through its collection activities. A detailed assessment of consumer LHFI delinquencies is performed monthly at both a product and market level by delivery channel, which incorporates the perceived level of risk at time of underwriting. The tables below present LHFI by loan type and credit quality indicator at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Commercial LHFI Pass - Special Mention - Substandard - Doubtful - Categories Category 7 Category 8 Category 9 Subtotal Loans secured by real estate: Construction, land development and other land $ 1,075,146 $ — $ 15,726 $ 42 $ 1,090,914 Secured by 1-4 family residential properties 116,592 45 6,355 41 123,033 Secured by nonfarm, nonresidential properties 2,430,761 — 44,001 328 2,475,090 Other real estate secured 721,238 — 2,547 — 723,785 Commercial and industrial loans 1,407,837 909 68,262 888 1,477,896 Consumer loans — — — — — State and other political subdivision loans 957,948 4,650 5,346 — 967,944 Other loans 469,095 3,445 16,926 30 489,496 Total $ 7,178,617 $ 9,049 $ 159,163 $ 1,329 $ 7,348,158 Consumer LHFI Past Due Past Due Current 30-89 Days 90 Days or More Nonaccrual Subtotal Total LHFI Loans secured by real estate: Construction, land development and other land $ 71,413 $ 332 $ — $ 132 $ 71,877 $ 1,162,791 Secured by 1-4 family residential properties 1,710,930 5,922 211 15,817 1,732,880 1,855,913 Secured by nonfarm, nonresidential properties 155 — — — 155 2,475,245 Other real estate secured 695 — — — 695 724,480 Commercial and industrial loans — — — — — 1,477,896 Consumer loans 172,649 2,588 393 108 175,738 175,738 State and other political subdivision loans — — — — — 967,944 Other loans 6,125 — — — 6,125 495,621 Total $ 1,961,967 $ 8,842 $ 604 $ 16,057 $ 1,987,470 $ 9,335,628 December 31, 2018 Commercial LHFI Pass - Special Mention - Substandard - Doubtful - Categories 1-6 Category 7 Category 8 Category 9 Subtotal Loans secured by real estate: Construction, land development and other land $ 982,305 $ 75 $ 5,645 $ 203 $ 988,228 Secured by 1-4 family residential properties 123,191 216 2,731 229 126,367 Secured by nonfarm, nonresidential properties 2,182,106 1,250 37,025 473 2,220,854 Other real estate secured 537,958 323 4,610 — 542,891 Commercial and industrial loans 1,468,262 12,431 55,943 2,079 1,538,715 Consumer loans — — — — — State and other political subdivision loans 958,214 5,250 10,354 — 973,818 Other loans 460,568 17,842 10,323 49 488,782 Total $ 6,712,604 $ 37,387 $ 126,631 $ 3,033 $ 6,879,655 Consumer LHFI Past Due Past Due Current 30-89 Days 90 Nonaccrual Subtotal Total LHFI Loans secured by real estate: Construction, land development and other land $ 67,913 $ 124 $ — $ 336 $ 68,373 $ 1,056,601 Secured by 1-4 family residential properties 1,675,455 9,872 569 13,229 1,699,125 1,825,492 Secured by nonfarm, nonresidential properties 60 — — — 60 2,220,914 Other real estate secured 929 — — — 929 543,820 Commercial and industrial loans — — — — — 1,538,715 Consumer loans 179,802 2,153 288 205 182,448 182,448 State and other political subdivision loans — — — — — 973,818 Other loans 5,278 — — — 5,278 494,060 Total $ 1,929,437 $ 12,149 $ 857 $ 13,770 $ 1,956,213 $ 8,835,868 Past Due LHFS LHFS past due 90 days or more totaled $41.6 million and $37.4 million at December 31, 2019 and 2018, respectively. Trustmark did not exercise its buy-back option on any delinquent loans serviced for GNMA during 2019 or 2018. Allowance for Loan Losses, LHFI Trustmark’s allowance for loan loss methodology for commercial LHFI is based upon regulatory guidance from its primary regulator and GAAP. The methodology segregates the commercial purpose and commercial construction LHFI portfolios into nine separate loan types (or pools) which have similar characteristics such as repayment, collateral and risk profiles. The nine basic loan pools are further segregated into Trustmark’s five key market regions, Alabama, Florida, Mississippi, Tennessee and Texas, to take into consideration the uniqueness of each market. A 10-point risk rating system is utilized for each separate loan pool to apply a reserve factor consisting of quantitative and qualitative components to determine the needed allowance by each loan type. As a result, there are 450 risk rate factors for commercial loan types. The nine separate pools are shown below: Commercial Purpose LHFI • Real Estate – Owner-Occupied • Real Estate – Nonowner-Occupied • Working Capital • Non-Working Capital • Land • Lots and Development • Political Subdivisions Commercial Construction LHFI • 1 to 4 Family • Non-1 to 4 Family The quantitative factors of the allowance methodology reflect a twelve-quarter rolling average of net charge-offs by loan type within each key market region. This allows for a greater sensitivity to current trends, such as economic changes, as well as current loss profiles and creates a more accurate depiction of historical losses. Qualitative factors used in the allowance methodology include the following: • National and regional economic trends and conditions • Impact of recent performance trends • Experience, ability and effectiveness of management • Adherence to Trustmark’s loan policies, procedures and internal controls • Collateral, financial and underwriting exception trends • Credit concentrations • Loan facility risk • Acquisitions • Catastrophe Each qualitative factor is converted to a scale ranging from 0 (No risk) to 100 (High Risk), other than the last two factors, which are applied on a dollar-for-dollar basis to ensure that the combination of such factors is proportional. The resulting ratings from the individual factors are weighted and summed to establish the weighted-average qualitative factor within each key market region. The allowance for loan loss methodology segregates the consumer LHFI portfolio into homogeneous pools of loans that contain similar structure, repayment, collateral and risk profiles. These homogeneous pools of loans are shown below: • Residential Mortgage • Direct Consumer • Junior Lien on 1-4 Family Residential Properties • Credit Cards • Overdrafts The historical loss experience for these pools is determined by calculating a 12-quarter rolling average of net charge-offs, which is applied to each pool to establish the quantitative aspect of the methodology. Where, in Management’s estimation, the calculated loss experience does not fully cover the anticipated loss for a pool, an estimate is also applied to each pool to establish the qualitative aspect of the methodology, which represents the perceived risks across the loan portfolio at the current point in time. This qualitative methodology utilizes five separate factors made up of unique components that when weighted and combined produce an estimated level of reserve for each of the loan pools. The five qualitative factors include the following: • Economic indicators • Performance trends • Management experience • Credit concentrations • Loan policy exceptions The risk measure for each factor is converted to a scale ranging from 0 (No risk) to 100 (High Risk) to ensure that the combination of such factors is proportional. The resulting ratings from the individual factors are weighted and summed to establish the weighted-average qualitative factor of a specific loan portfolio. This weighted-average qualitative factor is then applied over the five loan pools. Trustmark’s loan policy dictates the guidelines to be followed in determining when a loan is charged off. Commercial purpose loans are charged off when a determination is made that the loan is uncollectible and continuance as a bankable asset is not warranted or an impairment evaluation indicates that a value adjustment is necessary. Consumer loans secured by 1-4 family residential real estate are generally charged off or written down when the credit becomes severely delinquent and the balance exceeds the fair value of the property less costs to sell. Non-real estate consumer purpose loans, both secured and unsecured, are generally charged off in full during the month in which the loan becomes 120 days past due. Credit card loans are generally charged off in full when the loan becomes 180 days past due. The following tables detail the balance in the allowance for loan losses, LHFI allocated to each loan type segmented by the impairment evaluation methodology used at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ — $ 8,260 $ 8,260 Secured by 1-4 family residential properties 35 8,897 8,932 Secured by nonfarm, nonresidential properties 2,355 23,803 26,158 Other real estate secured — 4,024 4,024 Commercial and industrial loans 707 25,285 25,992 Consumer loans — 3,379 3,379 State and other political subdivision loans 1,809 420 2,229 Other loans 553 4,750 5,303 Total allowance for loan losses, LHFI $ 5,459 $ 78,818 $ 84,277 December 31, 2018 Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ — $ 7,390 $ 7,390 Secured by 1-4 family residential properties 39 8,602 8,641 Secured by nonfarm, nonresidential properties 413 21,963 22,376 Other real estate secured — 3,450 3,450 Commercial and industrial loans 4,334 23,025 27,359 Consumer loans — 2,890 2,890 State and other political subdivision loans 516 474 990 Other loans 1,052 5,142 6,194 Total allowance for loan losses, LHFI $ 6,354 $ 72,936 $ 79,290 The following tables detail LHFI by loan type related to each balance in the allowance for loan losses, LHFI segregated by the impairment evaluation methodology used at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 LHFI Evaluated for Impairment Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ 626 $ 1,162,165 $ 1,162,791 Secured by 1-4 family residential properties 5,464 1,850,449 1,855,913 Secured by nonfarm, nonresidential properties 6,717 2,468,528 2,475,245 Other real estate secured 68 724,412 724,480 Commercial and industrial loans 23,458 1,454,438 1,477,896 Consumer loans 21 175,717 175,738 State and other political subdivision loans 4,079 963,865 967,944 Other loans 784 494,837 495,621 Total $ 41,217 $ 9,294,411 $ 9,335,628 December 31, 2018 LHFI Evaluated for Impairment Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ 1,552 $ 1,055,049 $ 1,056,601 Secured by 1-4 family residential properties 3,963 1,821,529 1,825,492 Secured by nonfarm, nonresidential properties 9,476 2,211,438 2,220,914 Other real estate secured 248 543,572 543,820 Commercial and industrial loans 30,717 1,507,998 1,538,715 Consumer loans 2 182,446 182,448 State and other political subdivision loans 8,595 965,223 973,818 Other loans 1,282 492,778 494,060 Total $ 55,835 $ 8,780,033 $ 8,835,868 Changes in the allowance for loan losses, LHFI were as follows for the periods pr

Acquired Loans

Acquired Loans	12 Months Ended
	Dec. 31, 2019
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities [Abstract]
Acquired Loans	Note 6 – Acquired Loans Trustmark’s loss share agreement with the FDIC covering the acquired covered loans secured by 1-4 family residential properties will expire in 2021. At December 31, 2019 and 2018, acquired loans consisted of the following ($ in thousands): December 31, 2019 2018 Loans secured by real estate: Construction, land development and other land $ 4,771 $ 5,878 Secured by 1-4 family residential properties 17,525 22,556 Secured by nonfarm, nonresidential properties 38,206 47,979 Other real estate secured 3,946 8,253 Commercial and industrial loans 5,035 15,267 Consumer loans 520 1,356 Other loans 2,598 5,643 Acquired loans 72,601 106,932 Less allowance for loan losses, acquired loans 815 1,231 Net acquired loans $ 71,786 $ 105,701 The following table presents changes in the net carrying value of the acquired loans for the periods presented ($ in thousands): Acquired Impaired Acquired Not 310-30 (1) Carrying value, net at January 1, 2018 $ 179,570 $ 77,868 Transfers (2)(3) (26,497 ) (59,916 ) Accretion to interest income 9,514 1,019 Payments received, net (62,519 ) (16,234 ) Other (4) (26 ) 74 Change in allowance for loan losses, acquired loans 2,848 — Carrying value, net at December 31, 2018 102,890 2,811 Transfers (3) — (2,926 ) Accretion to interest income 5,532 115 Payments received, net (37,230 ) — Other (4) 178 — Change in allowance for loan losses, acquired loans 416 — Carrying value, net at December 31, 2019 $ 71,786 $ — (1) “Acquired Not ASC 310-30” loans consist of loans that are not in scope for FASB ASC Subtopic 310-30. (2) During 2018, Trustmark transferred the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions from acquired impaired loans to LHFI. (3) “Acquired Not ASC 310-30” loans transferred to LHFI due to the discount on these loans being fully amortized. (4) Includes miscellaneous timing adjustments as well as acquired loan terminations through foreclosure, charge-off and other terminations. Under FASB ASC Subtopic 310-30, the accretable yield is the excess of expected cash flows at acquisition over the initial fair value of acquired impaired loans and is recorded as interest income over the estimated life of the loans using the effective yield method if the timing and amount of the future cash flows is reasonably estimable. The following table presents changes in the accretable yield for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Accretable yield at beginning of period $ (17,722 ) $ (31,426 ) $ (38,918 ) Additions due to acquisition (1) — — (784 ) Accretion to interest income 5,532 9,514 14,924 Disposals, net 2,072 3,926 2,868 Transfers (2) — 5,874 — Reclassification from nonaccretable difference (3) (4,698 ) (5,610 ) (9,516 ) Accretable yield at end of period $ (14,816 ) $ (17,722 ) $ (31,426 ) (1) Accretable yield on loans acquired from Reliance on April 7, 2017. (2) During 2018, Trustmark transferred the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions from acquired impaired loans to LHFI. (3) Reclassifications from nonaccretable difference are due to lower loss expectations and improvements in expected cash flows. The following tables present the components of the allowance for loan losses on acquired impaired loans for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Balance at beginning of period $ 1,231 $ 4,079 $ 11,397 Transfers (1) — (1,554 ) — Provision for loan losses, acquired loans 42 (1,005 ) (7,395 ) Net (charge-offs) recoveries (458 ) (289 ) 77 Balance at end of period $ 815 $ 1,231 $ 4,079 (1) The allowance for loan losses balance related to the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions, which were transferred from acquired impaired loans to LHFI during 2018. As discussed in Note 5 - LHFI and Allowance for Loan Losses, LHFI, Trustmark has established a loan grading system that consists of ten individual credit risk grades (risk ratings) that encompass a range from loans where the expectation of loss is negligible to loans where loss has been established. The model is based on the risk of default for an individual credit and establishes certain criteria to segregate the level of risk across the ten unique risk ratings. These credit quality measures are unique to commercial loans. Credit quality for consumer loans is based on individual credit scores, aging status of the loan and payment activity. The tables below present the acquired loans by loan type and credit quality indicator at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Commercial Loans Pass - Special Mention - Substandard - Doubtful - Categories 1-6 Category 7 Category 8 Category 9 Subtotal Loans secured by real estate: Construction, land development and other land $ 4,022 $ — $ 192 $ — $ 4,214 Secured by 1-4 family residential properties 3,164 42 580 — 3,786 Secured by nonfarm, nonresidential properties 27,848 — 9,972 386 38,206 Other real estate secured 3,878 — 68 — 3,946 Commercial and industrial loans 3,419 — — 1,616 5,035 Consumer loans — — — — — Other loans 2,591 — 7 — 2,598 Total acquired loans $ 44,922 $ 42 $ 10,819 $ 2,002 $ 57,785 Consumer Loans Past Due Past Due Total Current 30-89 Days 90 Days or More Nonaccrual (1) Subtotal Acquired Loans Loans secured by real estate: Construction, land development and other land $ 463 $ 94 $ — $ — $ 557 $ 4,771 Secured by 1-4 family residential properties 12,843 615 281 — 13,739 17,525 Secured by nonfarm, nonresidential properties — — — — — 38,206 Other real estate secured — — — — — 3,946 Commercial and industrial loans — — — — — 5,035 Consumer loans 489 31 — — 520 520 Other loans — — — — — 2,598 Total acquired loans $ 13,795 $ 740 $ 281 $ — $ 14,816 $ 72,601 (1) Acquired loans not accounted for under FASB ASC Subtopic 310-30. December 31, 2018 Commercial Loans Pass - Special Mention - Substandard - Doubtful - Categories 1-6 Category 7 Category 8 Category 9 Subtotal Loans secured by real estate: Construction, land development and other land $ 4,923 $ 26 $ 278 $ — $ 5,227 Secured by 1-4 family residential properties 4,341 45 534 451 5,371 Secured by nonfarm, nonresidential properties 34,933 — 12,614 432 47,979 Other real estate secured 7,653 — 190 410 8,253 Commercial and industrial loans 6,560 — 6,942 1,765 15,267 Consumer loans — — — — — Other loans 4,027 — 1,616 — 5,643 Total acquired loans $ 62,437 $ 71 $ 22,174 $ 3,058 $ 87,740 Consumer Loans Past Due Past Due Total Current 30-89 Days 90 Days or More Nonaccrual (1) Subtotal Acquired Loans Loans secured by real estate: Construction, land development and other land $ 642 $ 5 $ 4 $ — $ 651 $ 5,878 Secured by 1-4 family residential properties 16,133 571 481 — 17,185 22,556 Secured by nonfarm, nonresidential properties — — — — — 47,979 Other real estate secured — — — — — 8,253 Commercial and industrial loans — — — — — 15,267 Consumer loans 1,346 10 — — 1,356 1,356 Other loans — — — — — 5,643 Total acquired loans $ 18,121 $ 586 $ 485 $ — $ 19,192 $ 106,932 (1) Acquired loans not accounted for under FASB ASC Subtopic 310-30 . The following tables provide an aging analysis of contractually past due and nonaccrual acquired loans by loan type at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Past Due 30-59 Days 60-89 Days 90 Days or More (1) Total Nonaccrual (2) Current Loans Total Acquired Loans Loans secured by real estate: Construction, land development and other land $ 94 $ — $ 38 $ 132 $ — $ 4,639 $ 4,771 Secured by 1-4 family residential properties 696 131 366 1,193 — 16,332 17,525 Secured by nonfarm, nonresidential properties 36 — 851 887 — 37,319 38,206 Other real estate secured 1 — 52 53 — 3,893 3,946 Commercial and industrial loans — — — — — 5,035 5,035 Consumer loans 16 15 — 31 — 489 520 Other loans — — — — — 2,598 2,598 Total acquired loans $ 843 $ 146 $ 1,307 $ 2,296 $ — $ 70,305 $ 72,601 (1) Past due 90 days or more but still accruing interest. (2) Acquired loans not accounted for under FASB ASC Subtopic 310-30. December 31, 2018 Past Due 30-59 Days 60-89 Days 90 Days or More (1) Total Nonaccrual (2) Current Loans Total Acquired Loans Loans secured by real estate: Construction, land development and other land $ 5 $ — $ 87 $ 92 $ — $ 5,786 $ 5,878 Secured by 1-4 family residential properties 664 108 481 1,253 — 21,303 22,556 Secured by nonfarm, nonresidential properties 206 — 978 1,184 — 46,795 47,979 Other real estate secured 2 14 — 16 — 8,237 8,253 Commercial and industrial loans — — — — — 15,267 15,267 Consumer loans 1 9 — 10 — 1,346 1,356 Other loans — — — — — 5,643 5,643 Total acquired loans $ 878 $ 131 $ 1,546 $ 2,555 $ — $ 104,377 $ 106,932 (1) Past due 90 days or more but still accruing interest. (2) Acquired loans not accounted for under FASB ASC Subtopic 310-30.

Premises and Equipment, Net

Premises and Equipment, Net	12 Months Ended
	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Premises and Equipment, Net	Note 7 – Premises and Equipment, Net At December 31, 2019 and 2018, premises and equipment, net consisted of the following ($ in thousands): December 31, 2019 2018 Land $ 52,454 $ 52,779 Buildings and leasehold improvements 210,362 202,912 Furniture and equipment 174,257 169,652 Total cost of premises and equipment 437,073 425,343 Less accumulated depreciation and amortization 256,608 247,160 Premises and equipment, net 180,465 178,183 Financing lease right-of-use assets 9,326 — Assets held for sale — 485 Total premises and equipment, net $ 189,791 $ 178,668 At December 31, 2019, there were no closed branches in assets held for sale compared to three closed branches at December 31, 2018. These properties were transferred from premises and equipment, net to assets held for sale while Trustmark sold these properties as a result of its strategic branch initiatives. As a result, there were no property valuation adjustments for 2019 compared to $173 thousand and $338 thousand recognized and included in other expense for 2018 and 2017, respectively. Depreciation and amortization of premises and equipment totaled $15.7 million in 2019 and $14.3 million in both 2018 and 2017.

Mortgage Banking

Mortgage Banking	12 Months Ended
	Dec. 31, 2019
Mortgage Banking [Abstract]
Mortgage Banking	Note 8 – Mortgage Banking Mortgage Servicing Rights The activity in the MSR is detailed in the table below for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 Balance at beginning of period $ 95,596 $ 84,269 Origination of servicing assets 16,711 15,759 Change in fair value: Due to market changes (21,078 ) 7,342 Due to runoff (11,835 ) (11,774 ) Balance at end of period $ 79,394 $ 95,596 Trustmark determines the fair value of the MSR using a valuation model administered by a third party that calculates the present value of estimated future net servicing income. Trustmark considers the conditional prepayment rate (CPR), which is an estimated loan prepayment rate that uses historical prepayment rates for previous loans similar to the loans being evaluated, and the discount rate in determining the fair value of the MSR. An increase in either the CPR or discount rate assumption will result in a decrease in the fair value of the MSR, while a decrease in either assumption will result in an increase in the fair value of the MSR. At December 31, 2019, the fair value of the MSR included an assumed average prepayment speed of 11 CPR and an average discount rate of 10.03% compared to an assumed average prepayment speed of 8 CPR and an average discount rate of 10.04% at December 31, 2018. In recent years, there have been significant market-driven fluctuations in loan prepayment speeds and discount rates. These fluctuations can be rapid and may continue to be significant. Therefore, estimating prepayment speed and/or discount rates within ranges that market participants would use in determining the fair value of the MSR requires significant management judgment. Mortgage Loans Sold/Serviced During 2019, 2018 and 2017, Trustmark sold $1.404 billion, $1.092 billion and $1.179 billion, respectively, of residential mortgage loans. Gain on sales of loans, net totaled $30.3 million in 2019, $21.8 million in 2018 and $18.8 million in 2017. Trustmark receives annual servicing fee income approximating 0.32% of the outstanding balance of the underlying loans, which totaled $22.6 million in 2019, $21.9 million in 2018 and $21.4 million in 2017. The gains on the sale of residential mortgage loans and the annual servicing fee are both recorded to noninterest income in mortgage banking, net in the accompanying consolidated statements of income. The investors and the securitization trusts have no recourse to the assets of Trustmark for failure of debtors to pay when due. The table below details the mortgage loans sold and serviced for others at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 2018 Federal National Mortgage Association $ 4,411,914 $ 4,204,336 Government National Mortgage Association 2,652,782 2,537,238 Federal Home Loan Mortgage Corporation 73,134 71,343 Other 19,404 21,957 Total mortgage loans sold and serviced for others $ 7,157,234 $ 6,834,874 Trustmark is subject to losses in its loan servicing portfolio due to loan foreclosures. Trustmark has obligations to either repurchase the outstanding principal balance of a loan or make the purchaser whole for the economic benefits of a loan if it is determined that the loan sold was in violation of representations or warranties made by Trustmark at the time of the sale, herein referred to as mortgage loan servicing putback expenses. Such representations and warranties typically include those made regarding loans that had missing or insufficient file documentation, loans that do not meet investor guidelines, loans in which the appraisal does not support the value and/or loans obtained through fraud by the borrowers or other third parties. Generally, putback requests may be made until the loan is paid in full. However, mortgage loans delivered to Federal National Mortgage Association (FNMA) and Federal Home Loan Mortgage Corporation (FHLMC) on or after January 1, 2013 are subject to the Lending and Selling Representations and Warranties Framework updated in May 2014, which provides certain instances in which FNMA and FHLMC will not exercise their remedies, including a putback request, for breaches of certain selling representations and warranties, such as payment history and quality control review. When a putback request is received, Trustmark evaluates the request and takes appropriate actions based on the nature of the request. Trustmark is required by FNMA and FHLMC to provide a response to putback requests within 60 days of the date of receipt. The total mortgage loan servicing putback expenses were included in other expense. At December 31, 2019 and 2018, Trustmark had a reserve for mortgage loan servicing putback expenses of $500 thousand and $1.0 million, respectively. There is inherent uncertainty in reasonably estimating the requirement for reserves against potential future mortgage loan servicing putback expenses. Future putback expenses are dependent on many subjective factors, including the review procedures of the purchasers and the potential refinance activity on loans sold with servicing released and the subsequent consequences under the representations and warranties. Trustmark believes that it has appropriately reserved for potential mortgage loan servicing putback requests.

Goodwill and Identifiable Intan

Goodwill and Identifiable Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Identifiable Intangible Assets	Note 9 – Goodwill and Identifiable Intangible Assets Goodwill The table below illustrates goodwill by segment for the years ended December 31, 2019 and 2018 ($ in thousands): General Banking Insurance Total Balance as of January 1, 2018 $ 334,603 $ 45,024 $ 379,627 Adjustment during 2018 — — — Balance as of December 31, 2018 334,603 45,024 379,627 Adjustment during 2019 — — — Balance as of December 31, 2019 $ 334,603 $ 45,024 $ 379,627 Trustmark’s General Banking Segment delivers a full range of banking services to consumer, corporate, small and middle-market businesses through its extensive branch network. The Insurance Segment includes TNB’s wholly-owned retail insurance subsidiary that offers a diverse mix of insurance products and services. Trustmark performed goodwill impairment tests for the General Banking and Insurance Segments during 2019, 2018 and 2017. Based on these tests, Trustmark concluded that the fair value of both the General Banking and Insurance Segments substantially exceeded the book value and no impairment charge was required. Identifiable Intangible Assets At December 31, 2019 and 2018, identifiable intangible assets consisted of the following ($ in thousands): December 31, 2019 December 31, 2018 Gross Accumulated Net Carrying Gross Carrying Accumulated Net Carrying Amount Amortization Amount Amount Amortization Amount Core deposit intangibles $ 87,674 $ 82,096 $ 5,578 $ 87,674 $ 78,353 $ 9,321 Insurance intangibles 14,171 12,655 1,516 13,824 12,348 1,476 Banking charters 1,325 1,076 249 1,325 1,010 315 Total $ 103,170 $ 95,827 $ 7,343 $ 102,823 $ 91,711 $ 11,112 Trustmark recorded $4.1 million of amortization of identifiable intangible assets in 2019, $5.2 million in 2018 and $6.2 million in 2017. Trustmark estimates that amortization expense for identifiable intangible assets will be $2.8 million in 2020, $2.0 million in 2021, $1.2 million in 2022, $411 thousand in 2023 and $224 thousand in 2024. Trustmark continually evaluates whether events and circumstances have occurred that indicate that identifiable intangible assets have become impaired. Measurement of any impairment of such identifiable intangible assets is based on the fair values of those assets. There were no impairment losses on identifiable intangible assets recorded during 2019, 2018 or 2017. The following table illustrates the carrying amounts and remaining weighted-average amortization periods of identifiable intangible assets as of December 31, 2019 ($ in thousands): Remaining Weighted- Average Net Carrying Amortization Amount Period in Core deposit intangibles $ 5,578 3.8 Insurance intangibles 1,516 12.9 Banking charters 249 3.7 Total $ 7,343 5.7

Other Real Estate

Other Real Estate	12 Months Ended
	Dec. 31, 2019
Other Real Estate And Foreclosed Assets [Abstract]
Other Real Estate	Note 10 – Other Real Estate At December 31, 2019, Trustmark’s geographic other real estate distribution was concentrated primarily in its five key market regions: Alabama, Florida, Mississippi, Tennessee and Texas. The ultimate recovery of a substantial portion of the carrying amount of other real estate is susceptible to changes in market conditions in these areas. For the periods presented, changes and gains (losses), net on other real estate were as follows ($ in thousands): Years Ended December 31, 2019 2018 2017 Balance at beginning of period $ 34,668 $ 43,228 $ 62,051 Additions (1) 8,598 12,115 9,235 Disposals (11,474 ) (19,802 ) (24,762 ) Write-downs (2,544 ) (873 ) (3,296 ) Balance at end of period $ 29,248 $ 34,668 $ 43,228 Gain (losses), net on the sale of other real estate included in other real estate expense $ (291 ) $ 700 $ 2,087 (1) For the year ended December 31, 2017, additions to other real estate included $475 thousand of other real estate acquired in the Reliance merger on April 7, 2017. At December 31, 2019 and 2018, other real estate by type of property consisted of the following ($ in thousands): December 31, 2019 2018 Construction, land development and other land properties $ 11,482 $ 16,206 1-4 family residential properties 3,453 4,983 Nonfarm, nonresidential properties 14,313 13,296 Other real estate properties — 183 Total other real estate $ 29,248 $ 34,668 At December 31, 2019 and 2018, other real estate by geographic location consisted of the following ($ in thousands): December 31, 2019 2018 Alabama $ 8,133 $ 6,873 Florida 5,877 8,771 Mississippi (1) 14,919 17,255 Tennessee (2) 319 1,025 Texas — 744 Total other real estate $ 29,248 $ 34,668 (1) Mississippi includes Central and Southern Mississippi Regions. (2) Tennessee includes Memphis, Tennessee and Northern Mississippi Regions. At December 31, 2019 and 2018, the balance of other real estate included $3.5 million and $5.0 million, respectively, of foreclosed residential real estate properties recorded as a result of obtaining physical possession of the

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Note 11 – Leases The table below details the components of net lease cost for the period presented ($ in thousands): Year Ended December 31, 2019 Finance leases Amortization of right-of-use assets $ 2,162 Interest on lease liabilities 307 Operating lease cost 5,183 Short-term lease cost 370 Variable lease cost 1,387 Sublease income (331 ) Net lease cost $ 9,078 The table below details the cash payments included in the measurement of lease liabilities during the period presented ($ in thousands): Year Ended December 31, 2019 Finance leases Operating cash flows included in operating activities $ 307 Financing cash flows included in payments under finance lease obligations 1,964 Operating leases Operating cash flows (fixed payments) included in other operating activities, net 5,092 Operating cash flows (liability reduction) included in other operating activities, net 5,404 The table below details balance sheet information, as well as weighted-average lease terms and discount rates, related to leases at December 31, 2019 ($ in thousands): December 31, 2019 Finance lease right-of-use assets, net of accumulated depreciation $ 9,326 Finance lease liabilities 9,520 Operating lease right-of-use assets 31,182 Operating lease liabilities 32,354 Weighted-average lease term Finance leases 8.62 years Operating leases 9.05 years Weighted-average discount rate Finance leases 3.01 % Operating leases 3.51 % At December 31, 2019, future minimum rental commitments under finance and operating leases were as follows ($ in thousands): Finance Leases Operating Leases 2020 $ 1,970 $ 4,916 2021 1,615 4,576 2022 1,556 4,101 2023 871 4,064 2024 572 3,968 Thereafter 4,451 16,349 Total minimum lease payments 11,035 37,974 Less imputed interest (1,515 ) (5,620 ) Lease liabilities $ 9,520 $ 32,354

Deposits

Deposits	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Deposits	Note 12 – Deposits At December 31, 2019 and 2018, deposits consisted of the following ($ in thousands): December 2019 2018 Noninterest-bearing demand $ 2,891,215 $ 2,937,594 Interest-bearing demand 3,125,914 2,633,259 Savings 3,590,509 3,905,659 Time 1,637,919 1,887,899 Total $ 11,245,557 $ 11,364,411 Interest expense on deposits by type consisted of the following for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Interest-bearing demand $ 35,428 $ 18,479 $ 6,820 Savings 19,462 17,980 6,047 Time 24,281 17,477 9,850 Total $ 79,171 $ 53,936 $ 22,717 Time deposits that exceed the FDIC insurance limit of $250 thousand totaled $285.7 million and $406.6 million at December 31, 2019 and 2018, respectively. The maturities of interest-bearing deposits at December 31, 2019, are as follows ($ in thousands): 2020 $ 1,359,100 2021 190,554 2022 50,364 2023 20,995 2024 14,316 Thereafter 2,590 Total time deposits 1,637,919 Interest-bearing deposits with no stated maturity 6,716,423 Total interest-bearing deposits $ 8,354,342

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Borrowings	Note 13 - Borrowings Securities Sold Under Repurchase Agreements Trustmark utilizes securities sold under repurchase agreements as a source of borrowing in connection with overnight repurchase agreements offered to commercial deposit customers by using its unencumbered investment securities as collateral. Trustmark accounts for its securities sold under repurchase agreements as secured borrowings in accordance with FASB ASC Subtopic 860-30, “Transfers and Servicing – Secured Borrowing and Collateral.” Securities sold under repurchase agreements are stated at the amount of cash received in connection with the transaction. Trustmark monitors collateral levels on a continual basis and may be required to provide additional collateral based on the fair value of the underlying securities. Securities sold under repurchase agreements are secured by securities with a carrying amount of $105.6 million and $163.3 million at December 31, 2019 and 2018, respectively. As of December 31, 2019, all repurchase agreements were short-term and consisted primarily of sweep repurchase arrangements, under which excess deposits are “swept” into overnight repurchase agreements with Trustmark. The following table presents the securities sold under repurchase agreements by collateral pledged at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 2018 Mortgage-backed securities Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA $ 24,282 $ 6,721 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 29,290 38,788 Total securities sold under repurchase agreements $ 53,572 $ 45,509 Other Borrowings At December 31, 2019 and 2018, other borrowings consisted of the following ($ in thousands): December 2019 2018 FHLB advances $ 811 $ 879 Serviced GNMA loans eligible for repurchase 57,062 61,564 Finance lease liabilities 9,520 — Other 18,003 17,442 Total other borrowings $ 85,396 $ 79,885 FHLB Advances At both December 31, 2019 and 2018, Trustmark had no outstanding short-term FHLB advances. At December 31, 2019 and 2018, Trustmark had $3.178 billion and $2.827 billion, respectively, available in additional borrowing capacity from the FHLB of Dallas. Trustmark incurred no interest expense on short-term FHLB advances in 2019, compared to $4.4 million of interest expense in 2018 and $11.4 million in 2017. At both December 31, 2019 and 2018, Trustmark had no outstanding long-term FHLB advances with the FHLB of Dallas. At both December 31, 2019 and 2018, Trustmark had two outstanding long-term FHLB advances totaling $811 thousand and $879 thousand, respectively, with the FHLB of Atlanta. Both of these advances were assumed through the BancTrust merger. The advances outstanding had fixed interest rates of 0.08% and 0.75% with outstanding balances of $135 thousand and $676 thousand at December 31, 2019 and $153 thousand and $726 thousand at December 31, 2018. At December 31, 2019, these advances had a weighted-average remaining maturity of 2.37 years with a weighted-average cost of 0.64% during 2019. At December 31, 2018, the outstanding long-term advances had a weighted-average remaining maturity of 3.41 years with a weighted-average cost of 0.63% during 2018. There was no fair market value adjustment associated with the BancTrust merger included in the long-term FHLB advances at December 31, 2019 and 2018. Trustmark’s long-term FHLB advances are collateralized by securities held in safekeeping with the FHLB of Atlanta. Trustmark incurred $5 thousand of interest expense on long-term FHLB advances in 2019, compared to $6 thousand of interest expense in 2018 and $566 thousand of interest expense in 2017. Junior Subordinated Debt Securities On August 18, 2006, Trustmark completed a private placement of $60.0 million of trust preferred securities through a newly formed Delaware trust affiliate, Trustmark Preferred Capital Trust I (the Trust). The trust preferred securities mature September 30, 2036, are redeemable at Trustmark’s option and bear interest at a variable rate per annum equal to the three-month LIBOR plus 1.72%. Under applicable regulatory guidelines, these trust preferred securities qualify as Tier 1 capital. The proceeds from the sale of the trust preferred securities were used by the Trust to purchase $61.9 million in aggregate principal amount of Trustmark’s junior subordinated debentures. The debentures were issued pursuant to a Junior Subordinated Indenture, dated August 18, 2006, between Trustmark, as issuer, and Wilmington Trust Company, National Association, as trustee. Like the trust preferred securities, the debentures bear interest at a variable rate per annum equal to the three-month LIBOR plus 1.72% and mature on September 30, 2036. The debentures may be redeemed at Trustmark’s option at any time. The interest payments by Trustmark will be used to pay the quarterly distributions payable by the Trust to the holder of the trust preferred securities. However, so long as no event of default has occurred under the debentures, Trustmark may defer interest payments on the debentures (in which case the Trust will also defer distributions otherwise due on the trust preferred securities) for up to 20 consecutive quarters. The debentures are subordinated to the prior payment of any other indebtedness of Trustmark that, by its terms, is not similarly subordinated. The trust preferred securities are recorded as a long-term liability on Trustmark’s balance sheet; however, for regulatory purposes the trust preferred securities are treated as Tier 1 capital under the rules of the Federal Reserve Board (FRB), Trustmark’s primary federal regulatory agency. Trustmark also entered into a Guarantee Agreement, dated August 18, 2006, pursuant to which it has agreed to guarantee the payment by the Trust of distributions on the trust preferred securities and the payment of principal of the trust preferred securities when due, either at maturity or on redemption, but only if and to the extent that the Trust fails to pay distributions on or principal of the trust preferred securities after having received interest payments or principal payments on the junior subordinated debentures from Trustmark for the purpose of paying those distributions or the principal amount of the trust preferred securities. As defined in applicable accounting standards, the Trust, a wholly-owned subsidiary of Trustmark, is considered a variable interest entity for which Trustmark is not the primary beneficiary. Accordingly, the accounts of the Trust are not included in Trustmark’s consolidated financial statements. At December 31, 2019 and 2018, assets for the Trust totaled $61.9 million, resulting from the investment in junior subordinated debentures issued by Trustmark. Liabilities and shareholder’s equity for the Trust also totaled $61.9 million at December 31, 2019 and 2018, resulting from the issuance of trust preferred securities in the amount of $60.0 million as well as $1.9 million in common securities issued to Trustmark. During 2019, net income for the Trust equaled $79 thousand resulting from interest income from the junior subordinated debt securities issued by Trustmark to the Trust, compared with net income of $74 thousand during 2018 and $55 thousand during 2017. Dividends issued to Trustmark by the Trust during 2019 totaled $79 thousand, compared to $74 thousand during 2018 and $55 thousand during 2017.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2019
Revenue From Contract With Customer [Abstract]
Revenue from Contracts with Customers	Note 14 – Revenue from Contracts with Customers The following table presents noninterest income disaggregated by reportable operating segment and revenue stream for the periods presented ($ in thousands): Year Ended December 31, 2019 Year Ended December 31, 2018 (1) Year Ended December 31, 2017 (1)(2) Topic 606 Not Topic 606 (3) Total Topic 606 Not Topic 606 (3) Total Topic 606 Not Topic 606 (3) Total General Banking Segment Service charges on deposit accounts $ 42,509 $ — $ 42,509 $ 43,614 $ — $ 43,614 $ 43,928 $ — $ 43,928 Bank card and other fees 27,972 3,706 31,678 26,904 1,897 28,801 27,958 250 28,208 Mortgage banking, net — 29,822 29,822 — 34,674 34,674 — 29,902 29,902 Wealth management 379 — 379 296 — 296 210 — 210 Other, net 9,527 (160 ) 9,367 6,762 (217 ) 6,545 6,547 7,234 13,781 Security gains (losses), net — — — — — — — 15 15 Total noninterest income $ 80,387 $ 33,368 $ 113,755 $ 77,576 $ 36,354 $ 113,930 $ 78,643 $ 37,401 $ 116,044 Wealth Management Segment Service charges on deposit accounts $ 94 $ — $ 94 $ 88 $ — $ 88 $ 75 $ — $ 75 Bank card and other fees 58 — 58 104 — 104 78 — 78 Wealth management 30,300 — 30,300 30,042 — 30,042 30,130 — 30,130 Other, net 306 103 409 69 117 186 20 118 138 Total noninterest income $ 30,758 $ 103 $ 30,861 $ 30,303 $ 117 $ 30,420 $ 30,303 $ 118 $ 30,421 Insurance Segment Insurance commissions $ 42,396 $ — $ 42,396 $ 40,481 $ — $ 40,481 $ 38,168 $ — $ 38,168 Other, net 33 — 33 5 — 5 30 — 30 Total noninterest income $ 42,429 $ — $ 42,429 $ 40,486 $ — $ 40,486 $ 38,198 $ — $ 38,198 Consolidated Service charges on deposit accounts $ 42,603 $ — $ 42,603 $ 43,702 $ — $ 43,702 $ 44,003 $ — $ 44,003 Bank card and other fees 28,030 3,706 31,736 27,008 1,897 28,905 28,036 250 28,286 Mortgage banking, net — 29,822 29,822 — 34,674 34,674 — 29,902 29,902 Insurance commissions 42,396 — 42,396 40,481 — 40,481 38,168 — 38,168 Wealth management 30,679 — 30,679 30,338 — 30,338 30,340 — 30,340 Other, net 9,866 (57 ) 9,809 6,836 (100 ) 6,736 6,597 7,352 13,949 Security gains (losses), net — — — — — — — 15 15 Total noninterest income $ 153,574 $ 33,471 $ 187,045 $ 148,365 $ 36,471 $ 184,836 $ 147,144 $ 37,519 $ 184,663 (1) During the first quarter of 2019, Trustmark revised the composition of its operating segments by moving the Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes. The prior period amounts presented include reclassifications to conform to the current period presentation. (2) Trustmark elected the modified retrospective approach of adoption; therefore, prior period balances are presented under legacy GAAP and may not be comparable to current year presentation. (3) Noninterest income not in scope for FASB ASC Topic 606 includes customer derivatives revenue and miscellaneous credit card income within bank card and other fees; mortgage banking, net; amortization of tax credits, accretion of the FDIC indemnification asset, cash surrender value on various life insurance policies, earnings on Trustmark’s non-qualified deferred compensation plans, other partnership investments and rental income within other, net; and securities gains (losses), net.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Note 15 – Income Taxes The income tax provision included in the consolidated statements of income was as follows for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Current Federal $ 20,068 $ 4,532 $ 16,959 State 7,145 5,997 5,687 Deferred Federal (3,104 ) 9,392 7,280 State (776 ) 2,348 1,820 Income tax provision excluding deferred tax asset revaluation and reversal of valuation allowance 23,333 22,269 31,746 Deferred tax expense (benefit) - re-measurement of deferred tax assets — — 25,619 Deferred tax expense (benefit) - reversal of valuation allowance — — (8,650 ) Income tax provision $ 23,333 $ 22,269 $ 48,715 Trustmark maintained a valuation allowance for deferred tax assets of $8.7 million at December 31, 2016 that was related to unrealized built-in losses from a prior acquisition. Trustmark determined that based on the weight of the available evidence that it is more likely than not that all deferred tax assets will be realized as of December 31, 2017. Therefore, the valuation allowance was reversed as of December 31, 2017, resulting in a decrease of $8.7 million to income tax expense for the year. The re-measurement of the deferred tax assets and liabilities during 2017 resulted from the enactment of the Tax Reform Act, which was signed into law on December 22, 2017. Under the Tax Reform Act, corporate statutory income tax rates were reduced from 35.0% to 21.0% effective January 1, 2018. Trustmark re-measured its deferred tax assets and liabilities to reflect the future realization of these assets and liabilities at the lower tax rate. This re-measurement resulted in an increase to tax expense and a decrease to the net deferred tax asset of $25.6 million for the year ended December 31, 2017. For the periods presented, the income tax provision differs from the amount computed by applying the statutory federal income tax rate in effect for each respective period to income before income taxes as a result of the following ($ in thousands): Years Ended December 31, 2019 2018 2017 Income tax computed at statutory tax rate $ 36,497 $ 36,089 $ 54,021 Tax exempt interest (4,951 ) (4,533 ) (7,611 ) Nondeductible interest expense 564 416 407 State income taxes, net 5,645 4,738 3,697 Income tax credits, net (13,473 ) (15,404 ) (15,793 ) Death benefit gains (123 ) (268 ) (3,268 ) Reversal of valuation allowance — — (8,650 ) Re-measurement of deferred tax assets — — 25,619 Other (826 ) 1,231 293 Income tax provision $ 23,333 $ 22,269 $ 48,715 Temporary differences between the financial statement carrying amounts and the tax basis of assets and liabilities gave rise to the following net deferred tax assets at December 31, 2019 and 2018, which are included in other assets on the accompanying consolidated balance sheets ($ in thousands): December 31, 2019 2018 Deferred tax assets: Loan purchase accounting $ 845 $ 1,564 Other real estate 5,845 7,284 Allowance for loan losses 21,774 20,638 Deferred compensation 16,498 15,607 Financing and operating lease liabilities 10,469 — Realized built-in losses 11,431 12,182 Securities 3,028 3,929 Pension and other postretirement benefit plans 5,194 4,108 Interest on nonaccrual loans 942 806 Unrealized losses on securities available for sale — 10,679 Stock-based compensation 2,527 2,192 Federal carryovers — 1,606 Other 8,790 9,179 Gross deferred tax asset 87,343 89,774 Deferred tax liabilities: Goodwill and other identifiable intangibles 15,336 16,229 Premises and equipment 11,913 12,109 Financing and operating lease right-of-use assets 10,127 — Mortgage servicing rights 11,002 14,415 Securities 2,115 1,519 Other 5,192 5,600 Gross deferred tax liability 55,685 49,872 Net deferred tax asset $ 31,658 $ 39,902 The following table provides a summary of the changes during the 2019 calendar year in the amount of unrecognized tax benefits that are included in other liabilities in the consolidated balance sheet ($ in thousands): Balance at January 1, 2019 $ 1,249 Change due to tax positions taken during the current year 279 Change due to tax positions taken during a prior year 134 Change due to the lapse of applicable statute of limitations during the current year (138 ) Change due to settlements with taxing authorities during the current year — Balance at December 31, 2019 $ 1,524 Accrued interest, net of federal benefit, at December 31, 2019 $ 271 Unrecognized tax benefits that would impact the effective tax rate, if recognized, at December 31, 2019 $ 1,218 Interest and penalties related to unrecognized tax benefits, if any, are recorded in income tax expense. With limited exception, Trustmark is no longer subject to U.S. federal, state and local audits by tax authorities for 2013 and earlier tax years. Trustmark does not anticipate a significant change to the total amount of unrecognized tax benefits within the next twelve months.

Defined Benefit and Other Postr

Defined Benefit and Other Postretirement Benefits	12 Months Ended
	Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Defined Benefit and Other Postretirement Benefits	Note 16 – Defined Benefit and Other Postretirement Benefits Qualified Pension Plans Trustmark Capital Accumulation Plan Trustmark maintained a noncontributory tax-qualified defined benefit pension plan titled the Trustmark Capital Accumulation Plan (the Plan) in which substantially all associates who began employment prior to 2007 participated. The Plan provided for retirement benefits based on the length of credited service and final average compensation, as defined in the Plan, which vested upon three years of service. Benefit accruals under the Plan were frozen in 2009, with the exception of benefit accruals for certain employees of acquired financial institutions covered through plans that were subsequently merged into the Plan. Other than certain employees of acquired financial institutions, associates have not earned additional benefits, except for interest as required by law, since the Plan was frozen. Current and former associates who participated in the Plan retained their right to receive benefits that accrued before the Plan was frozen. As previously reported, on July 26, 2016 the Board of Directors of Trustmark authorized the termination of the Plan, effective as of December 31, 2016. As a result of the termination of the Plan, each participant became fully vested in their accrued benefits under the Plan. During the second quarter of 2017, Trustmark fully funded the Plan on a termination basis by contributing additional assets in the amount of $17.6 million in accordance with Internal Revenue Service (IRS) and Pension Benefit Guaranty Corporation requirements. Participants in the Plan elected to receive either a lump sum cash payment or annuity payments under a group annuity contract purchased from an insurance carrier. Final distributions were made to participants from the Plan assets and a one-time pension settlement expense was recognized totaling $17.6 million. Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions To satisfy commitments made by Trustmark to associates covered through plans obtained in acquisitions and subsequently merged into the Plan (collectively, the Continuing Associates), on July 26, 2016, the Board of Directors of Trustmark also approved the spin-off of the portion of the Plan associated with the accrued benefits of the Continuing Associates into a new plan titled the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions (the Continuing Plan), effective as of December 30, 2016, immediately prior to the termination of the Plan. The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for the Continuing Plan and the Plan for the periods presented ($ in thousands): December 31, 2019 2018 Change in benefit obligation: Benefit obligation, beginning of year $ 9,179 $ 10,102 Service cost 211 277 Interest cost 361 332 Actuarial (gain) loss 875 (827 ) Benefits paid (1,566 ) (705 ) Benefit obligation, end of year $ 9,060 $ 9,179 Change in plan assets: Fair value of plan assets, beginning of year $ 3,954 $ 4,596 Actual return on plan assets 668 (314 ) Employer contributions 387 377 Benefit payments (1,566 ) (705 ) Fair value of plan assets, end of year $ 3,443 $ 3,954 Funded status at end of year - net liability $ (5,617 ) $ (5,225 ) Amounts recognized in accumulated other comprehensive loss: Net loss - amount recognized $ 1,893 $ 2,170 Years Ended December 31, 2019 2018 2017 Net periodic benefit cost: Service cost $ 211 $ 277 $ 253 Interest cost 361 332 1,461 Expected return on plan assets (202 ) (227 ) (317 ) Recognized net loss due to defined benefit plan termination — — 17,662 Recognized net loss due to lump sum settlements 312 161 — Recognized net actuarial loss 373 571 1,414 Net periodic benefit cost $ 1,055 $ 1,114 $ 20,473 Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes: Net loss - Total recognized in other comprehensive income (loss) $ (277 ) $ (1,017 ) $ (18,168 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ 778 $ 97 $ 2,305 Weighted-average assumptions as of end of year: Discount rate for benefit obligation 2.84 % 3.97 % 3.32 % Discount rate for net periodic benefit cost 3.97 % 3.32 % 3.71 % Expected long-term return on plan assets 5.00 % 5.00 % 5.00 % Plan Assets The weighted-average asset allocations by asset category are presented below for the Continuing Plan at December 31, 2019 and 2018. December 31, 2019 2018 Money market fund 2.0 % 8.0 % Exchange traded funds: Equity securities 46.0 % 52.0 % Fixed income 41.0 % 29.0 % International 11.0 % 11.0 % Total 100.0 % 100.0 % The strategic objective of the investments of the assets in the Continuing Plan aims to provide long-term capital growth with moderate income. The allocation is managed on a total return basis with the average participant age in mind. It is constructed with an intermediate investment time frame with a moderate to high risk tolerance or a long-term investment time frame with a low to moderate risk tolerance. The plan allocation is typically balanced between equity and fixed income. The equity exposure has the potential to earn a return greater than inflation while the fixed income exposure may reduce the risk and volatility of the portfolio to which the equity allocation contributes. Fair Value Measurements At this time, Trustmark presents no fair values that are derived through internal modeling. Should positions requiring fair valuation arise that are not relevant to existing methodologies, Trustmark will make every reasonable effort to obtain market participant assumptions, or independent evaluation. The following table sets forth by level, within the fair value hierarchy, the Continuing Plan’s assets measured at fair value at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Total Level 1 Level 2 Level 3 Money market fund $ 51 $ 51 $ — $ — Exchange traded funds: Equity securities 1,592 1,592 — — Fixed income 1,417 1,417 — — International 383 383 — — Total assets at fair value $ 3,443 $ 3,443 $ — $ — December 31, 2018 Total Level 1 Level 2 Level 3 Money market fund $ 304 $ 304 $ — $ — Exchange traded funds: Equity securities 2,044 2,044 — — Fixed income 1,162 1,162 — — International 444 444 — — Total assets at fair value $ 3,954 $ 3,954 $ — $ — There have been no changes in the methodologies used in estimating the fair value of plan assets at December 31, 2019. The money market fund approximates fair value due to its immediate maturity. The preceding methods described may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, although Trustmark believes their valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date. Contributions The range of potential contributions to the Continuing Plan is determined annually by the Continuing Plan’s actuary in accordance with applicable IRS rules and regulations. Trustmark’s policy is to fund amounts that are sufficient to satisfy the annual minimum funding requirements and do not exceed the maximum that is deductible for federal income tax purposes. The actual amount of the contribution is determined annually based on the Continuing Plan’s funded status and return on plan assets as of the measurement date, which is December 31. For the plan year ending December 31, 2019, Trustmark’s minimum required contribution to the Continuing Plan was $157 thousand; however, Trustmark contributed $285 thousand. For the plan year ending December 31, 2020, Trustmark’s minimum required contribution to the Continuing Plan is expected to be $175 thousand; however, Management and the Board of Directors of Trustmark will monitor the Continuing Plan throughout 2020 to determine any additional funding requirements by the plan’s measurement date. Estimated Future Benefit Payments and Other Disclosures The following table presents the expected benefit payments, which reflect expected future service, for the Continuing Plan ($ in thousands): Year Amount 2020 $ 1,147 2021 1,056 2022 873 2023 1,220 2024 997 2025 - 2029 2,443 Amounts in accumulated other comprehensive loss expected to be recognized as components of net periodic benefit cost during 2020 include a net loss of $324 thousand. Supplemental Retirement Plans Trustmark maintains a nonqualified supplemental retirement plan covering key executive officers and senior officers as well as directors who have elected to defer fees. The plan provides for retirement and/or death benefits based on a participant’s covered salary or deferred fees. Although plan benefits may be paid from Trustmark’s general assets, Trustmark has purchased life insurance contracts on the participants covered under the plan, which may be used to fund future benefit payments under the plan. The measurement date for the plan is December 31. As a result of mergers prior to 2014, Trustmark became the administrator of small nonqualified supplemental retirement plans, for which the plan benefits were frozen prior to the merger date. The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for Trustmark’s nonqualified supplemental retirement plans for the periods presented ($ in thousands): December 31, 2019 2018 Change in benefit obligation: Benefit obligation, beginning of year $ 53,257 $ 57,930 Service cost 109 116 Interest cost 2,044 1,865 Actuarial (gain) loss 5,498 (3,228 ) Benefits paid (3,426 ) (3,426 ) Benefit obligation, end of year $ 57,482 $ 53,257 Change in plan assets: Fair value of plan assets, beginning of year $ — $ — Employer contributions 3,426 3,426 Benefit payments (3,426 ) (3,426 ) Fair value of plan assets, end of year $ — $ — Funded status at end of year - net liability $ (57,482 ) $ (53,257 ) Amounts recognized in accumulated other comprehensive loss: Net loss $ 18,275 $ 13,403 Prior service cost 609 859 Amounts recognized $ 18,884 $ 14,262 Years Ended December 31, 2019 2018 2017 Net periodic benefit cost: Service cost $ 109 $ 116 $ 141 Interest cost 2,044 1,865 2,103 Amortization of prior service cost 250 250 250 Recognized net actuarial loss 627 884 866 Net periodic benefit cost $ 3,030 $ 3,115 $ 3,360 Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes: Net (gain) loss $ 4,872 $ (4,111 ) $ (224 ) Amortization of prior service cost (250 ) (250 ) (250 ) Total recognized in other comprehensive income (loss) $ 4,622 $ (4,361 ) $ (474 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ 7,652 $ (1,246 ) $ 2,886 Weighted-average assumptions as of end of year: Discount rate for benefit obligation 2.84 % 3.97 % 3.32 % Discount rate for net periodic benefit cost 3.97 % 3.32 % 3.71 % Estimated Supplemental Retirement Plan Payments and Other Disclosures The following table presents the expected benefits payments for Trustmark’s supplemental retirement plans ($ in thousands): Year Amount 2020 $ 3,963 2021 4,051 2022 4,284 2023 4,124 2024 4,144 2025 - 2029 17,840 Amounts in accumulated other comprehensive loss expected to be recognized as components of net periodic benefit cost during 2020 include a loss of $957 thousand and prior service cost of $149 thousand. Other Benefit Plans Defined Contribution Plan Trustmark provides associates with a self-directed 401(k) retirement plan that allows associates to contribute a percentage of base pay, within limits provided by the Internal Revenue Code and accompanying regulations, into the plan. Trustmark matches 100% of associate contributions to the plan based on the amount of each participant’s contributions up to a maximum of 6% of eligible compensation. Associates may become eligible to make elective deferral contributions the first of the month following 30 days of employment. Eligible associates must complete one year of service in order to vest in Trustmark’s matching contributions. Trustmark’s contributions to this plan were $8.2 million in 2019, $7.9 million in 2018 and $7.5 million in 2017.

Stock and Incentive Compensatio

Stock and Incentive Compensation Plans	12 Months Ended
	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock and Incentive Compensation Plans	Note 17 – Stock and Incentive Compensation Plans Trustmark has granted stock and incentive compensation awards subject to the provisions of the Stock and Incentive Compensation Plan (the Stock Plan). Current outstanding and future grants of stock and incentive compensation awards are subject to the provisions of the Stock Plan, which is designed to provide flexibility to Trustmark regarding its ability to motivate, attract and retain the services of key associates and directors. The Stock Plan also allows Trustmark to grant nonqualified stock options, incentive stock options, stock appreciation rights, restricted stock, restricted stock units and performance units to key associates and directors. At December 31, 2019, the maximum number of shares of Trustmark’s common stock available for issuance under the Stock Plan was 909,818 shares. Restricted Stock Grants Performance Awards Trustmark’s performance awards vest over three years and are granted to Trustmark’s executive and senior management teams. Performance awards granted vest based on performance goals of return on average tangible equity and total shareholder return. Performance awards are valued utilizing a Monte Carlo simulation model to estimate fair value of the awards at the grant date. These awards are recognized using the straight-line method over the requisite service period. These awards provide for achievement shares if performance measures exceed 100%. The restricted share agreement provides for voting rights and dividend privileges. The following table summarizes Trustmark’s performance award activity for the periods presented: Years Ended December 31, 2019 2018 2017 Weighted- Weighted- Weighted- Average Average Average Grant-Date Grant-Date Grant-Date Shares Fair Value Shares Fair Value Shares Fair Value Nonvested shares, beginning of year 177,695 $ 27.10 213,516 $ 25.37 237,136 $ 26.27 Granted 50,862 33.44 51,174 31.88 58,406 33.31 Released from restriction (61,347 ) 20.18 (55,351 ) 25.32 (67,279 ) 34.78 Forfeited (17,296 ) 20.18 (31,644 ) 26.26 (14,747 ) 28.42 Nonvested shares, end of year 149,914 $ 32.88 177,695 $ 27.10 213,516 $ 25.37 Time-Vested Awards Trustmark’s time-vested awards vest over three years and are granted to members of Trustmark’s Board of Directors as well as Trustmark’s executive and senior management teams. Time-vested awards are valued utilizing the fair value of Trustmark’s stock at the grant date. These awards are recognized on the straight-line method over the requisite service period. The following table summarizes Trustmark’s time-vested award activity for the periods presented: Years Ended December 31, 2019 2018 2017 Weighted- Weighted- Weighted- Average Average Average Grant-Date Grant-Date Grant-Date Shares Fair Value Shares Fair Value Shares Fair Value Nonvested shares, beginning of year 321,870 $ 28.48 320,357 $ 25.40 322,056 $ 22.65 Granted 113,673 33.42 118,325 31.96 105,524 33.79 Released from restriction (124,598 ) 21.64 (107,180 ) 23.02 (101,289 ) 25.35 Forfeited (10,939 ) 32.73 (9,632 ) 29.30 (5,934 ) 26.52 Nonvested shares, end of year 300,006 $ 33.04 321,870 $ 28.48 320,357 $ 25.40 The following table presents information regarding compensation expense for awards under the Stock Plan for the periods presented ($ in thousands): At December 31, 2019 Recognized Compensation Expense Unrecognized Weighted Average for Years Ended December 31, Compensation Life of 2019 2018 2017 Expense Compensation Expense Performance awards $ 1,524 $ 861 $ 1,387 $ 1,914 1.59 Time-vested awards 3,263 3,009 2,922 3,726 1.73 Total $ 4,787 $ 3,870 $ 4,309 $ 5,640

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 18 – Commitments and 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 December 31, 2019 and 2018, Trustmark had unused commitments to extend credit of $4.349 billion and $3.918 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 December 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 $105.2 million and $100.2 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 December 31, 2019 and 2018, the fair value of collateral held was $26.3 million and $29.8 million, respectively. Legal Proceedings Trustmark’s wholly-owned subsidiary, TNB, has been named as a defendant in several lawsuits related to the collapse of the Stanford Financial Group. On August 23, 2009, a purported class action complaint was filed 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 and one individual, each of which are 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. Class Plaintiffs have demanded a jury trial. Class 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 4, 2016, the OSIC filed a First Amended Intervenor Complaint, which added claims for (i) aiding, abetting or participation in violations of the Texas Securities Act and (ii) aiding, abetting or participation in the breach of fiduciary duty. On November 7, 2017, the court denied the Class Plaintiffs’ 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. On May 3, 2019, individual investors and entities filed motions to intervene in the action. On September 18, 2019, the court denied the motions to intervene. On October 14, 2019, certain of the proposed intervenors filed a notice of appeal. On December 14, 2009, a different Stanford-related lawsuit was filed in the District Court of Ascension Parish, Louisiana, individually by Harold Jackson, Paul Blaine and 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 different 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. On November 1, 2019, TNB was named as a defendant in a complaint filed by Paul Blaine Smith, Carolyn Bass Smith and other plaintiffs identified therein (the Smith Complaint). The Smith Complaint was filed in District Court, Harris County, Texas and named TNB and four other financial institutions and one individual, each of which are unaffiliated with Trustmark, as defendants. The Smith Complaint relates to the collapse of the Stanford Financial Group, as does the other pending litigation relating to Stanford summarized above. Plaintiffs in the Smith Complaint have demanded a jury trial. Trustmark has only recently become aware of the Smith Complaint (which has not yet been served upon TNB). Trustmark and its counsel are carefully evaluating the Smith Complaint in the form that is publicly available, and will update the foregoing description to the extent that additional material facts are ascertained. 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. On December 30, 2019, a complaint was filed in the United States District Court for the Southern District of Mississippi, Northern Division (the Court) by Alysson Mills in her capacity as Court-appointed Receiver (the Receiver) for Arthur Lamar Adams (Adams) and Madison Timber Properties, LLC (Madison Timber), naming TNB, two other Mississippi-based financial institutions both of which are unaffiliated with Trustmark and two individuals, one of who was employed by TNB at all times relevant to the complaint and the other was employed either by TNB or one of the other defendant financial institutions, as defendants. The complaint seeks to recover from the defendants, for the benefit of the receivership estate and also for certain investors who were allegedly defrauded by Adams and Madison Timber, damages (including punitive damages) and related costs allegedly attributable to actions of the defendants that allegedly enabled illegal and fraudulent activities engaged in by Adams and Madison Timber. The Receiver did not quantify damages. TNB’s relationship with Adams and Madison Timber consisted of traditional banking services in the ordinary course of business. 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 Subtopic 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.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2019
Stockholders Equity Note [Abstract]
Shareholders' Equity	Note 19 – Shareholders’ Equity Regulatory Capital Trustmark and TNB are subject to minimum risk-based capital and leverage capital requirements, as described in the section captioned “Capital Adequacy” included in Part I. Item 1. – Business of this report, which are administered by the federal bank regulatory agencies. These capital requirements, as defined by federal regulations, involve quantitative and qualitative measures of assets, liabilities and certain off-balance sheet instruments. Trustmark’s and TNB’s minimum risk-based capital requirements include the phased in capital conservation buffer of % at December 31, 201 9 and % at December 31, 201 8 . Accumulated other comprehensive loss, net of tax, is not included in computing regulatory capital. Failure to meet minimum capital requirements can result in certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the financial statements of Trustmark and TNB and limit Trustmark’s and TNB’s ability to pay dividends. As of December 31, 2019 , Trustmark and TNB exceeded all applicable minimum capital standards. In addition, Trustmark and TNB met applicable regulatory guidelines to be considered well-capitalized at December 31, 2019 . To be categorized in this manner, Trustmark and TNB maintained minimum common equity Tier 1 risk-based capital, Tier 1 risk-based capital, total risk-based capital and Tier 1 leverage ratios as set forth in the accompanying table, and were not subject to any written agreement, order or capital directive, or prompt corrective action directive issued by their primary federal regulators to meet and maintain a specific capital level for any capital measures. There are no significant conditions or events that have occurred since December 31, 2019 , which Management believes have affected Trustmark’s or TNB’s present classification. The following table provides Trustmark’s and TNB’s actual regulatory capital amounts and ratios under regulatory capital standards in effect at December 31, 2019 and 2018 ($ in thousands): Actual Regulatory Capital Minimum To Be Well Amount Ratio Requirement Capitalized At December 31, 2019: Common Equity Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,312,668 11.93 % 7.000 % n/a Trustmark National Bank 1,352,893 12.30 % 7.000 % 6.50 % Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,372,668 12.48 % 8.500 % n/a Trustmark National Bank 1,352,893 12.30 % 8.500 % 8.00 % Total Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,457,760 13.25 % 10.500 % n/a Trustmark National Bank 1,437,985 13.07 % 10.500 % 10.00 % Tier 1 Leverage (to Average Assets) Trustmark Corporation $ 1,372,668 10.48 % 4.00 % n/a Trustmark National Bank 1,352,893 10.35 % 4.00 % 5.00 % At December 31, 2018: Common Equity Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,271,538 11.77 % 6.375 % n/a Trustmark National Bank 1,311,548 12.14 % 6.375 % 6.50 % Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,331,538 12.33 % 7.875 % n/a Trustmark National Bank 1,311,548 12.14 % 7.875 % 8.00 % Total Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,412,059 13.07 % 9.875 % n/a Trustmark National Bank 1,392,069 12.89 % 9.875 % 10.00 % Tier 1 Leverage (to Average Assets) Trustmark Corporation $ 1,331,538 10.26 % 4.00 % n/a Trustmark National Bank 1,311,548 10.13 % 4.00 % 5.00 % Dividends on Common Stock Dividends paid by Trustmark are substantially funded from dividends received from TNB. Approval by TNB’s regulators is required if the total of all dividends declared in any calendar year exceeds the total of its net income for that year combined with its retained net income of the preceding two years. In 2020, TNB will have available approximately $56.8 million plus its net income for that year to pay as dividends. Stock Repurchase Program On March 11, 2016, the Board of Directors of Trustmark authorized a stock repurchase program under which $100.0 million of Trustmark’s outstanding common stock could be acquired through March 31, 2019. Trustmark repurchased approximately 1.2 million shares of its common stock valued at $36.9 million during the year ended December 31, 2019, compared to 2.0 million shares of its common stock valued at $62.4 million repurchased during the year ended December 31, 2018 and no common stock repurchased during the year ended December 31, 2017. Under the 2016 program, Trustmark repurchased approximately 3.2 million shares valued at $100.0 million. The Board of Directors of Trustmark authorized a stock repurchase program effective April 1, 2019 under which $100.0 million of Trustmark’s outstanding common stock may be acquired through March 31, 2020. The adoption of this stock repurchase program followed the receipt of non-objection from the FRB. The shares may be purchased from time to time at prevailing market prices, through open market or privately negotiated transactions, depending on market conditions. Under this authority, Trustmark repurchased approximately 601 thousand shares of its common stock valued at $19.7 million during the year ended December 31, 2019. Together, with the repurchases under the 2016 program, Trustmark purchased approximately 1.8 million shares of its common stock valued at $56.6 million during the year ended December 31, 2019. On January 28, 2020, the Board of Directors of Trustmark authorized a new stock repurchase program effective April 1, 2020 under which $100.0 million of Trustmark’s outstanding common stock may be acquired through December 31, 2021. The shares may be purchased from time to time at prevailing market prices, through open market or privately negotiated transactions, depending on market conditions. There is no guarantee as to the number of shares that may be repurchased by Trustmark, and Trustmark may discontinue purchases at any time at Management’s discretion. Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss The following tables present the net change in the components of accumulated other comprehensive loss and the related tax effects allocated to each component for the years ended December 31, 2019, 2018 and 2017 ($ in thousands). Reclassification adjustments related to securities available for sale are included in securities gains (losses), net in the accompanying consolidated statements of income. The amortization of prior service cost, recognized net loss due to lump sum settlements, change in net actuarial loss and recognized net loss due to defined benefit plan termination for pension and other postretirement benefit plans are included in the computation of net periodic benefit cost (see Note 16 – Defined Benefit and Other Postretirement Benefits for additional details). Reclassification adjustments related to pension and other postretirement benefit plans are included in salaries and employee benefits, defined benefit plan termination and other expense in the accompanying consolidated statements of income. Reclassification adjustments related to the cash flow hedge derivative are included in other interest expense in the accompanying consolidated statements of income. Before Tax Tax Net of Tax Amount Benefit Amount Year Ended December 31, 2019 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ 44,136 $ (11,033 ) $ 33,103 Change in net unrealized holding loss on securities transferred to held to maturity 3,605 (901 ) 2,704 Total securities available for sale and transferred securities 47,741 (11,934 ) 35,807 Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans (5,703 ) 1,425 (4,278 ) Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (63 ) 187 Recognized net loss due to lump sum settlements 312 (77 ) 235 Change in net actuarial loss 796 (199 ) 597 Total pension and other postretirement benefit plans (4,345 ) 1,086 (3,259 ) Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives (145 ) 36 (109 ) Reclassification adjustment for (gain) loss realized in net income (479 ) 119 (360 ) Total cash flow hedge derivatives (624 ) 155 (469 ) Total other comprehensive income (loss) $ 42,772 $ (10,693 ) $ 32,079 Year Ended December 31, 2018 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ (19,221 ) $ 4,805 $ (14,416 ) Change in net unrealized holding loss on securities transferred to held to maturity 3,761 (940 ) 2,821 Total securities available for sale and transferred securities (15,460 ) 3,865 (11,595 ) Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans 3,742 (936 ) 2,806 Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (63 ) 187 Recognized net loss due to lump sum settlements 161 (39 ) 122 Change in net actuarial loss 1,225 (306 ) 919 Total pension and other postretirement benefit plans 5,378 (1,344 ) 4,034 Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives 497 (124 ) 373 Reclassification adjustment for (gain) loss realized in net income (322 ) 80 (242 ) Total cash flow hedge derivatives 175 (44 ) 131 Total other comprehensive income (loss) $ (9,907 ) $ 2,477 $ (7,430 ) Year Ended December 31, 2017 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ (13,994 ) $ 5,353 $ (8,641 ) Reclassification adjustment for net (gains) losses realized in net income (15 ) 6 (9 ) Change in net unrealized holding loss on securities transferred to held to maturity 4,721 (1,806 ) 2,915 Total securities available for sale and transferred securities (9,288 ) 3,553 (5,735 ) Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans (1,231 ) 471 (760 ) Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (96 ) 154 Change in net actuarial loss 1,962 (751 ) 1,211 Recognized net loss due to defined benefit plan termination 17,662 (6,755 ) 10,907 Total pension and other postretirement benefit plans 18,643 (7,131 ) 11,512 Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives 198 (76 ) 122 Reclassification adjustment for (gain) loss realized in net income 282 (108 ) 174 Total cash flow hedge derivatives 480 (184 ) 296 Total other comprehensive income (loss) $ 9,835 $ (3,762 ) $ 6,073 The following table presents the changes in the balances of each component of accumulated other comprehensive loss for the periods presented ($ in thousands). All amounts are presented net of tax. Securities Available and Securities Defined Benefit Pension Items Cash Flow Hedge Derivative Total Balance, January 1, 2017 $ (20,800 ) $ (24,980 ) $ (18 ) $ (45,798 ) Other comprehensive income (loss) before reclassification (5,726 ) (760 ) 122 (6,364 ) Amounts reclassified from accumulated other comprehensive loss (9 ) 12,272 174 12,437 Net other comprehensive income (loss) (5,735 ) 11,512 296 6,073 Balance, December 31, 2017 (26,535 ) (13,468 ) 278 (39,725 ) Other comprehensive income (loss) before reclassification (11,595 ) 2,806 373 (8,416 ) Amounts reclassified from accumulated other comprehensive loss — 1,228 (242 ) 986 Net other comprehensive income (loss) (11,595 ) 4,034 131 (7,430 ) Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act (5,694 ) (2,890 ) 60 (8,524 ) Balance, December 31, 2018 (43,824 ) (12,324 ) 469 (55,679 ) Other comprehensive income (loss) before reclassification 35,807 (4,278 ) (109 ) 31,420 Amounts reclassified from accumulated other comprehensive loss — 1,019 (360 ) 659 Net other comprehensive income (loss) 35,807 (3,259 ) (469 ) 32,079 Balance, December 31, 2019 $ (8,017 ) $ (15,583 ) $ — $ (23,600 )

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value	Note 20 – Fair Value Financial Instruments Measured at Fair Value The methodologies Trustmark uses in determining the fair values are based primarily on the use of independent, market-based data to reflect a value that would be reasonably expected upon exchange of the position in an orderly transaction between market participants at the measurement date. The predominant portion of assets that are stated at fair value are of a nature that can be valued using prices or inputs that are readily observable through a variety of independent data providers. The providers selected by Trustmark for fair valuation data are widely recognized and accepted vendors whose evaluations support the pricing functions of financial institutions, investment and mutual funds, and portfolio managers. Trustmark has documented and evaluated the pricing methodologies used by the vendors and maintains internal processes that regularly test valuations for anomalies. Trustmark utilizes an independent pricing service to advise it on the carrying value of the securities available for sale portfolio. As part of Trustmark’s procedures, the price provided from the service is evaluated for reasonableness given market changes. When a questionable price exists, Trustmark investigates further to determine if the price is valid. If needed, other market participants may be utilized to determine the correct fair value. Trustmark has also reviewed and confirmed its determinations in thorough discussions with the pricing source regarding their methods of price discovery. Mortgage loan commitments are valued based on the securities prices of similar collateral, term, rate and delivery for which the loan is eligible to deliver in place of the particular security. Trustmark acquires a broad array of mortgage security prices that are supplied by a market data vendor, which in turn accumulates prices from a broad list of securities dealers. Prices are processed through a mortgage pipeline management system that accumulates and segregates all loan commitment and forward-sale transactions according to the similarity of various characteristics (maturity, term, rate, and collateral). Prices are matched to those positions that are deemed to be an eligible substitute or offset (i.e., “deliverable”) for a corresponding security observed in the market place. Trustmark estimates fair value of the MSR through the use of prevailing market participant assumptions and market participant valuation processes. This valuation is periodically tested and validated against other third-party firm valuations. Trustmark obtains the fair value of interest rate swaps from a third-party pricing service that uses an industry standard discounted cash flow methodology. In addition, credit valuation adjustments are incorporated in the fair values to account for potential nonperformance risk. In adjusting the fair value of its interest rate swap contracts for the effect of nonperformance risk, Trustmark has considered any applicable credit enhancements such as collateral postings, thresholds, mutual puts, and guarantees. In conjunction with the FASB’s fair value measurement guidance, Trustmark made an accounting policy election to measure the credit risk of these derivative financial instruments, which are subject to master netting agreements, on a net basis by counterparty portfolio. Trustmark has determined that the majority of the inputs used to value its interest rate swaps offered to qualified commercial borrowers fall within Level 2 of the fair value hierarchy, while the credit valuation adjustments associated with these derivatives utilize Level 3 inputs, such as estimates of current credit spreads. Trustmark has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its interest rate swaps and has determined that the credit valuation adjustment is not significant to the overall valuation of these derivatives. As a result, Trustmark classifies its interest rate swap valuations in Level 2 of the fair value hierarchy. Trustmark also utilizes exchange-traded derivative instruments such as Treasury note futures contracts and option contracts to achieve a fair value return that offsets the changes in fair value of the MSR attributable to interest rates. Fair values of these derivative instruments are determined from quoted prices in active markets for identical assets therefore allowing them to be classified within Level 1 of the fair value hierarchy. In addition, Trustmark utilizes derivative instruments such as interest rate lock commitments in its mortgage banking area which lack observable inputs for valuation purposes resulting in their inclusion in Level 3 of the fair value hierarchy. At this time, Trustmark presents no fair values that are derived through internal modeling. Should positions requiring fair valuation arise that are not relevant to existing methodologies, Trustmark will make every reasonable effort to obtain market participant assumptions, or independent evaluation. Financial Assets and Liabilities The following tables summarize financial assets and financial liabilities measured at fair value on a recurring basis as of December 31, 2019 and 2018, segregated by the level of valuation inputs within the fair value hierarchy utilized to measure fair value ($ in thousands). There were no transfers between fair value levels for the years ended December 31, 2019 and 2018. December 31, 2019 Total Level 1 Level 2 Level 3 U.S. Government agency obligations $ 22,327 $ — $ 22,327 $ — Obligations of states and political subdivisions 25,465 — 25,465 — Mortgage-backed securities 1,554,612 — 1,554,612 — Securities available for sale 1,602,404 — 1,602,404 — Loans held for sale 226,347 — 226,347 — Mortgage servicing rights 79,394 — — 79,394 Other assets - derivatives 17,956 244 16,273 1,439 Other liabilities - derivatives 6,063 4,414 1,649 — December 31, 2018 Total Level 1 Level 2 Level 3 U.S. Government agency obligations $ 30,335 $ — $ 30,335 $ — Obligations of states and political subdivisions 50,676 — 50,676 — Mortgage-backed securities 1,730,802 — 1,730,802 — Securities available for sale 1,811,813 — 1,811,813 — Loans held for sale 153,799 — 153,799 — Mortgage servicing rights 95,596 — — 95,596 Other assets - derivatives 12,347 5,006 6,154 1,187 Other liabilities - derivatives 4,213 66 4,147 — The changes in Level 3 assets measured at fair value on a recurring basis for the years ended December 31, 2019 and 2018 are summarized as follows ($ in thousands): MSR Other Assets - Derivatives Balance, January 1, 2019 $ 95,596 $ 1,187 Total net (loss) gain included in Mortgage banking, net (1) (32,913 ) 6,775 Additions 16,711 — Sales — (6,523 ) Balance, December 31, 2019 $ 79,394 $ 1,439 The amount of total gains (losses) for the period included in earnings that are attributable to the change in unrealized gains or losses still held at December 31, 2019 $ (21,078 ) $ 1,284 Balance, January 1, 2018 $ 84,269 $ 900 Total net (loss) gain included in Mortgage banking, net (1) (4,432 ) 4,390 Additions 15,759 — Sales — (4,103 ) Balance, December 31, 2018 $ 95,596 $ 1,187 The amount of total gains (losses) for the period included in earnings that are attributable to the change in unrealized gains or losses still held at December 31, 2018 $ 7,342 $ 636 (1) Total net (loss) gain included in Mortgage banking, net relating to the MSR includes changes in fair value due to market changes and due to run-off. Trustmark may be required, from time to time, to measure certain assets at fair value on a nonrecurring basis in accordance with GAAP. Assets at December 31, 2019, which have been measured at fair value on a nonrecurring basis, include impaired LHFI. Loans for which it is probable Trustmark will be unable to collect the scheduled payments of principal or interest when due according to the contractual terms of the loan agreement are considered impaired. Specific allowances for impaired LHFI are based on comparisons of the recorded carrying values of the loans to the present value of the estimated cash flows of these loans at each loan’s original effective interest rate, the fair value of the collateral or the observable market prices of the loans. Impaired LHFI are primarily collateral dependent loans and are assessed using a fair value approach. Fair value estimates for collateral dependent loans are derived from appraised values based on the current market value or as-is value of the property being appraised, normally from recently received and reviewed appraisals. Appraisals are obtained from state-certified appraisers and are based on certain assumptions, which may include construction or development status and the highest and best use of the property. These appraisals are reviewed by Trustmark’s Appraisal Review Department to ensure they are acceptable. Appraised values are adjusted down for costs associated with asset disposal. At December 31, 2019, Trustmark had outstanding balances of $41.2 million with a related allowance of $5.5 million in impaired LHFI that were individually evaluated for impairment and written down to fair value of the underlying collateral less cost to sell based on the fair value of the collateral or other unobservable input compared to $55.8 million with a related allowance of $6.4 million at December 31, 2018. These individually evaluated impaired LHFI are classified as Level 3 in the fair value hierarchy. Impaired LHFI are periodically reviewed and evaluated for additional impairment and adjusted accordingly based on the same factors identified above. Nonfinancial Assets and Liabilities Certain nonfinancial assets measured at fair value on a nonrecurring basis include foreclosed assets (upon initial recognition or subsequent impairment), nonfinancial assets and nonfinancial liabilities measured at fair value in the second step of a goodwill impairment test, and intangible assets and other nonfinancial long-lived assets measured at fair value for impairment assessment. Other real estate includes assets that have been acquired in satisfaction of debt through foreclosure and is carried at the lower of cost or estimated fair value. Fair value is based on independent appraisals and other relevant factors. In the determination of fair value subsequent to foreclosure, Management also considers other factors or recent developments, such as changes in market conditions from the time of valuation and anticipated sales values considering plans for disposition, which could result in an adjustment to lower the collateral value estimates indicated in the appraisals. Periodic revaluations are classified as Level 3 in the fair value hierarchy since assumptions are used that may not be observable in the market. Foreclosed assets of $15.0 million were re-measured during 2019, requiring write-downs of $2.4 million to reach their current fair values compared to $19.2 million of foreclosed assets that were re-measured during 2018, requiring write-downs of $873 thousand. Fair Value of Financial Instruments FASB ASC Topic 825 requires disclosure of the fair value of financial assets and financial liabilities, including those financial assets and financial liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis. The carrying amounts and estimated fair values of financial instruments at December 31, 2019 and 2018 were as follows ($ in thousands): December 31, 2019 December 31, 2018 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Financial Assets: Level 2 Inputs: Cash and short-term investments $ 358,916 $ 358,916 $ 350,391 $ 350,391 Securities held to maturity 738,099 746,202 909,643 889,733 Level 3 Inputs: Net LHFI 9,251,351 9,235,674 8,756,578 8,757,817 Net acquired loans 71,786 71,786 105,701 105,701 Financial Liabilities: Level 2 Inputs: Deposits 11,245,557 11,250,071 11,364,411 11,365,203 Federal funds purchased and securities sold under repurchase agreements 256,020 256,020 50,471 50,471 Other borrowings 85,396 85,374 79,885 79,827 Junior subordinated debt securities 61,856 50,722 61,856 53,196 Fair Value Option Trustmark has elected to account for its LHFS under the fair value option, with interest income on these LHFS reported in interest and fees on LHFS and LHFI. The fair value of the LHFS is determined using quoted prices for a similar asset, adjusted for specific attributes of that loan. The LHFS are actively managed and monitored and certain market risks of the loans may be mitigated through the use of derivatives. These derivative instruments are carried at fair value with changes in fair value recorded as noninterest income in mortgage banking, net. The changes in the fair value of the LHFS are largely offset by changes in the fair value of the derivative instruments. For the years ended December 31, 2019, 2018 and 2017, a net gain of $1.5 million, $1.4 million and $3.0 million, respectively, was recorded as noninterest income in mortgage banking, net for changes in the fair value of the LHFS accounted for under the fair value option. Interest and fees on LHFS and LHFI for the years ended December 31, 2019 included $5.9 million of interest earned on the LHFS accounted for under the fair value option compared to $4.9 million for both years ended December 31, 2018 and 2017. Election of the fair value option allows Trustmark to reduce the accounting volatility that would otherwise result from the asymmetry created by accounting for the financial instruments at the lower of cost or fair value and the derivatives at fair value. The fair value option election does not apply to the GNMA optional repurchase loans which do not meet the requirements under FASB ASC Topic 825 to be accounted for under the fair value option. GNMA optional repurchase loans totaled $57.1 million and $61.6 million at December 31, 2019 and 2018, respectively, and are included in LHFS on the accompanying consolidated balance sheets. The following table provides information about the fair value and the contractual principal outstanding of the LHFS accounted for under the fair value option as of December 31, 2019 and 2018 ($ in thousands): December 31, 2019 2018 Fair value of LHFS $ 169,285 $ 92,235 LHFS contractual principal outstanding 164,420 89,056 Fair value less unpaid principal $ 4,865 $ 3,179

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2019
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Note 21 – Derivative Financial Instruments Derivatives Designated as Hedging Instruments On April 4, 2013, Trustmark entered into a forward interest rate swap contract on junior subordinated debentures with a total notional amount of $60.0 million. The interest rate swap contract was designated as a derivative instrument in a cash flow hedge under FASB ASC Topic 815 with the objective of protecting the quarterly interest payments on Trustmark’s $60.0 million of junior subordinated debentures issued to Trustmark Preferred Capital Trust I throughout the five-year period which beg an December 31, 2014 and end ed December 31, 2019 from the risk of variability of those payments resulting from changes in the three-month LIBOR interest rate. Under the swap, which became effective on December 31, 2014, Trustmark paid a fixed interest rate of 1.66 % and receive d a variable interest rate based on three-month LIBOR on a total notional amount of $60.0 million, with quarterly net settlements. No ineffectiveness related to the interest rate swap designated as a cash flow hedge was recognized in the consolidated statements of income for the years ended December 31, 2019, 2018 and 2017. The interest rate swap matured on December 31, 2019; therefore, there was no accumulated net after-tax amount related to the effective cash flow hedge included in accumulated other comprehensive loss at December 31, 2019 compared to a net after-tax gain of $469 thousand at December 31, 2018. Amounts reported in accumulated other comprehensive loss related to this derivative were reclassified to other interest expense as interest payments were made on Trustmark’s variable rate junior subordinated debentures. Derivatives not Designated as Hedging Instruments Trustmark utilizes a portfolio of exchange-traded derivative instruments, such as Treasury note futures contracts and option contracts, to achieve a fair value return that economically hedges changes in the fair value of the MSR attributable to interest rates. These transactions are considered freestanding derivatives that do not otherwise qualify for hedge accounting. The total notional amount of these derivative instruments was $564.0 million at December 31, 2019 compared to $318.0 million at December 31, 2018. Changes in the fair value of these exchange-traded derivative instruments are recorded as noninterest income in mortgage banking, net and are offset by changes in the fair value of the MSR. The impact of this strategy resulted in a net negative ineffectiveness of $11.5 million for the year ended December 31, 2019, compared to a net positive ineffectiveness of $2.4 million for the year ended December 31, 2018 and a net positive ineffectiveness of $254 thousand for the year ended December 31, 2017. As part of Trustmark’s risk management strategy in the mortgage banking area, derivative instruments such as forward sales contracts are utilized. Trustmark’s obligations under forward sales contracts consist of commitments to deliver mortgage loans, originated and/or purchased, in the secondary market at a future date. Changes in the fair value of these derivative instruments are recorded as noninterest income in mortgage banking, net and are offset by changes in the fair value of LHFS. Trustmark’s off-balance sheet obligations under these derivative instruments totaled $209.0 million at December 31, 2019, with a negative valuation adjustment of $486 thousand, compared to $132.0 million at December 31, 2018, with a negative valuation adjustment of $1.8 million. Trustmark also utilizes derivative instruments such as interest rate lock commitments in its mortgage banking area. Interest rate lock commitments are residential mortgage loan commitments with customers, which guarantee a specified interest rate for a specified time period. Changes in the fair value of these derivative instruments are recorded as noninterest income in mortgage banking, net and are offset by the changes in the fair value of forward sales contracts. Trustmark’s off-balance sheet obligations under these derivative instruments totaled $92.1 million at December 31, 2019, with a positive valuation adjustment of $1.4 million, compared to $71.2 million at December 31, 2018, with a positive valuation adjustment of $1.2 million. Trustmark offers certain derivatives products directly to qualified commercial lending clients seeking to manage their interest rate risk. Trustmark economically hedges interest rate swap transactions executed with commercial lending clients by entering into offsetting interest rate swap transactions with institutional derivatives market participants. Derivatives transactions executed as part of this program are not designated as qualifying hedging relationships and are, therefore, carried at fair value with the change in fair value recorded as noninterest income in bank card and other fees. Because these derivatives have mirror-image contractual terms, in addition to collateral provisions which mitigate the impact of non-performance risk, the changes in fair value are expected to substantially offset. As of December 31, 2019, Trustmark had interest rate swaps with an aggregate notional amount of $893.1 million related to this program, compared to $475.8 million as of December 31, 2018. Credit-risk-related Contingent Features Trustmark has agreements with its financial institution counterparties that contain provisions where if Trustmark defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then Trustmark could also be declared in default on its derivatives obligations. As of December 31, 2019 and 2018, the termination value of interest rate swaps in a liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, related to these agreements was $1.0 million and $75 thousand, respectively. As of December 31, 2019, Trustmark had posted collateral of $1.4 million against its obligations because of negotiated thresholds and minimum transfer amounts under these agreements. If Trustmark had breached any of these triggering provisions at December 31, 2019, it could have been required to settle its obligations under the agreements at the termination value. Credit risk participation agreements arise when Trustmark contracts with other financial institutions, as a guarantor or beneficiary, to share credit risk associated with certain interest rate swaps. These agreements provide for reimbursement of losses resulting from a third party default on the underlying swap. At both December 31, 2019 and 2018, Trustmark had entered into three risk participation agreements as a beneficiary with aggregate notional amounts of $37.6 million and $23.1 million, respectively. At December 31, 2019, Trustmark had entered into ten risk participation agreements as a guarantor with an aggregate notional amount of $79.3 million compared to seven risk participation agreements as a guarantor with an aggregate notional amount of $39.0 million at December 31, 2018. The aggregate fair values of these risk participation agreements were immaterial at December 31, 2019 and 2018. Tabular Disclosures The following tables disclose the fair value of derivative instruments in Trustmark’s consolidated balance sheets as of December 31, 2019 and 2018 as well as the effect of these derivative instruments on Trustmark’s results of operations for the periods presented ($ in thousands): December 31, 2019 2018 Derivatives in hedging relationships Interest rate contracts: Interest rate swaps included in other assets $ — $ 625 Derivatives not designated as hedging instruments Interest rate contracts: Futures contracts included in other assets $ — $ 4,445 Exchange traded purchased options included in other assets 244 561 OTC written options (rate locks) included in other assets 1,439 1,187 Interest rate swaps included in other assets 16,209 5,487 Credit risk participation agreements included in other assets 64 42 Futures contracts included in other liabilities 2,654 — Forward contracts included in other liabilities 486 1,773 Exchange traded written options included in other liabilities 1,760 66 Interest rate swaps included in other liabilities 1,122 2,369 Credit risk participation agreements included in other liabilities 41 5 Years Ended December 31, 2019 2018 2017 Derivatives in hedging relationships Amount of gain (loss) reclassified from accumulated other comprehensive loss and recognized in other interest expense $ 479 $ 322 $ (282 ) Derivatives not designated as hedging instruments Amount of gain (loss) recognized in mortgage banking, net $ 11,096 $ (6,191 ) $ (1,873 ) Amount of gain (loss) recognized in bank card and other fees (776 ) (357 ) (31 ) The following table discloses the amount included in other comprehensive income (loss), net of tax, for derivative instruments designated as cash flow hedges for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Derivatives in cash flow hedging relationship Amount of gain (loss) recognized in other comprehensive income (loss), net of tax $ (109 ) $ 373 $ 122 Information about financial instruments that are eligible for offset in the consolidated balance sheets as of December 31, 2019 and 2018 is presented in the following tables ($ in thousands): Offsetting of Derivative Assets As of December 31, 2019 Gross Statement of Financial Position Gross Amounts of Recognized Assets Gross Amounts Offset in the Statement of Financial Position Net Amounts of Assets presented in the Statement of Financial Position Financial Instruments Cash Collateral Received Net Amount Derivatives $ 16,209 $ — $ 16,209 $ — $ — $ 16,209 Offsetting of Derivative Liabilities As of December 31, 2019 Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Statement of Financial Position Net Amounts of Liabilities presented in the Statement of Financial Position Financial Instruments Cash Collateral Posted Net Amount Derivatives $ 1,122 $ — $ 1,122 $ — $ (1,390 ) $ (268 ) Offsetting of Derivative Assets As of December 31, 2018 Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Assets Gross Amounts Offset in the Statement of Financial Position Net Amounts of Assets presented in Financial Position Financial Instruments Cash Collateral Received Net Amount Derivatives $ 6,112 $ — $ 6,112 $ (339 ) $ (620 ) $ 5,153 Offsetting of Derivative Liabilities As of December 31, 2018 Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Statement of Financial Position Net Amounts of Liabilities presented in the Statement of Financial Position Financial Instruments Cash Collateral Posted Net Amount Derivatives $ 2,369 $ — $ 2,369 $ (339 ) $ — $ 2,030

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segment Information	Note 22 – Segment Information Trustmark’s management reporting structure includes three segments: General Banking, Wealth Management and Insurance. The General Banking Segment is responsible for all traditional banking products and services, including loans and deposits. The General Banking Segment also consists of internal operations such as Human Resources, Executive Administration, Treasury (Funds Management), Public Affairs and Corporate Finance. The Wealth Management Segment provides customized solutions for customers by integrating financial services with traditional banking products and services such as money management, full-service brokerage, financial planning, personal and institutional trust and retirement services. Through Fisher Brown Bottrell Insurance, Inc. (FBBI), a wholly owned subsidiary of TNB, Trustmark’s Insurance Segment provides a full range of retail insurance products including commercial risk management products, bonding, group benefits and personal lines coverage. During the first quarter of 2019, Trustmark revised the composition of its operating segments by moving the Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for reporting purposes. The prior periods presented include reclassifications to conform to the current period presentation. The accounting policies of each reportable segment are the same as those of Trustmark except for its internal allocations. Noninterest expenses for back-office operations support are allocated to segments based on estimated uses of those services. Trustmark measures the net interest income of its business segments with a process that assigns cost of funds or earnings credit on a matched-term basis. This process, called “funds transfer pricing”, charges an appropriate cost of funds to assets held by a business unit, or credits the business unit for potential earnings for carrying liabilities. The net of these charges and credits flows through to the General Banking Segment, which contains the management team responsible for determining TNB’s funding and interest rate risk strategies. The following table discloses financial information by reportable segment for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 General Banking Net interest income $ 422,661 $ 415,561 $ 402,507 Provision for loan losses, net 10,838 17,001 7,485 Noninterest income 113,755 113,930 116,044 Noninterest expense 370,493 355,389 370,793 Income before income taxes 155,085 157,101 140,273 Income taxes 18,721 18,560 43,427 General banking net income $ 136,364 $ 138,541 $ 96,846 Selected Financial Information Total assets $ 13,333,518 $ 13,111,362 $ 13,627,012 Depreciation and amortization $ 38,637 $ 38,182 $ 37,704 Wealth Management Net interest income $ 3,686 $ 3,633 $ 4,809 Provision for loan losses, net 1 (13 ) 214 Noninterest income 30,861 30,420 30,421 Noninterest expense 26,365 29,170 29,989 Income before income taxes 8,181 4,896 5,027 Income taxes 2,040 1,225 1,923 Wealth Management net income $ 6,141 $ 3,671 $ 3,104 Selected Financial Information Total assets $ 90,113 $ 106,179 $ 102,773 Depreciation and amortization $ 267 $ 186 $ 137 Insurance Net interest income $ 242 $ 226 $ 234 Noninterest income 42,429 40,486 38,198 Noninterest expense 32,144 30,856 29,387 Income before income taxes 10,527 9,856 9,045 Income taxes 2,572 2,484 3,365 Insurance net income $ 7,955 $ 7,372 $ 5,680 Selected Financial Information Total assets $ 74,246 $ 68,919 $ 68,168 Depreciation and amortization $ 516 $ 572 $ 630 Consolidated Net interest income $ 426,589 $ 419,420 $ 407,550 Provision for loan losses, net 10,839 16,988 7,699 Noninterest income 187,045 184,836 184,663 Noninterest expense 429,002 415,415 430,169 Income before income taxes 173,793 171,853 154,345 Income taxes 23,333 22,269 48,715 Consolidated net income $ 150,460 $ 149,584 $ 105,630 Selected Financial Information Total assets $ 13,497,877 $ 13,286,460 $ 13,797,953 Depreciation and amortization $ 39,420 $ 38,940 $ 38,471

Parent Company Only Financial I

Parent Company Only Financial Information	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Parent Company Only Financial Information	Note 23 – Parent Company Only Financial Information ($ in thousands) Condensed Balance Sheets December 31, 2019 2018 Assets: Investment in banks $ 1,707,644 $ 1,637,338 Other assets 15,778 16,975 Total Assets $ 1,723,422 $ 1,654,313 Liabilities and Shareholders' Equity: Accrued expense $ 864 $ 1,004 Junior subordinated debt securities 61,856 61,856 Shareholders' equity 1,660,702 1,591,453 Total Liabilities and Shareholders' Equity $ 1,723,422 $ 1,654,313 Condensed Statements of Income Years Ended December 31, 2019 2018 2017 Revenue: Dividends received from banks $ 120,297 $ 128,592 $ 65,663 Earnings of subsidiaries over distributions 32,971 23,791 42,211 Other income 90 86 71 Total Revenue 153,358 152,469 107,945 Expense: Other expense 2,898 2,885 2,315 Total Expense 2,898 2,885 2,315 Net Income $ 150,460 $ 149,584 $ 105,630 Condensed Statements of Cash Flows Years Ended December 31, 2019 2018 2017 Operating Activities: Net income $ 150,460 $ 149,584 $ 105,630 Adjustments to reconcile net income to net cash provided by operating activities: Net change in investment in subsidiaries (32,971 ) (23,791 ) (42,211 ) Other (1,800 ) (1,395 ) (1,697 ) Net cash from operating activities 115,689 124,398 61,722 Investing Activities: Payment for investments in subsidiaries — — (30,755 ) Repayment for investments in subsidiaries — — 32,000 Net cash from investing activities — — 1,245 Financing Activities: Common stock dividends (59,804 ) (62,425 ) (62,795 ) Repurchase and retirement of common stock (56,615 ) (62,421 ) — Net cash from financing activities (116,419 ) (124,846 ) (62,795 ) Net change in cash and cash equivalents (730 ) (448 ) 172 Cash and cash equivalents at beginning of year 16,437 16,885 16,713 Cash and cash equivalents at end of year $ 15,707 $ 16,437 $ 16,885 Trustmark (parent company only) paid income taxes of approximately $24.8 million in 2019, $12.4 million in 2018 and $7.4 million in 2017. During 2019 and 2018, interest received was $482 thousand and $320 thousand, respectively, compared to $283 thousand of interest paid during 2017.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Business	Business Trustmark Corporation (Trustmark) is a bank holding company headquartered in Jackson, Mississippi. Through its subsidiaries, Trustmark operates as a financial services organization providing banking and financial solutions to corporate institutions and individual customers through 193 offices in Alabama, Florida, Mississippi, Tennessee and Texas.
Basis of Financial Statement Presentation	Basis of Financial Statement Presentation The consolidated financial statements include the accounts of Trustmark and all other entities in which Trustmark has a controlling financial interest. All significant intercompany accounts and transactions have been eliminated in consolidation. The consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (GAAP). The preparation of financial statements in conformity with these accounting principles requires Management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and income and expense during the reporting periods and the related disclosures. Although Management’s estimates contemplate current conditions and how they are expected to change in the future, it is reasonably possible that in 2020 actual conditions could vary from those anticipated, which could affect Trustmark’s financial condition and results of operations. Actual results could differ from those estimates.
Securities	Securities Securities are classified as either held to maturity or available for sale. Securities are classified as held to maturity and carried at amortized cost when Management has the positive intent and the ability to hold them until maturity. Securities to be held for indefinite periods of time are classified as available for sale and carried at fair value, with the unrealized holding gains and losses reported as a component of other comprehensive income (loss), net of tax. Securities available for sale are used as part of Trustmark’s interest rate risk management strategy and may be sold in response to changes in interest rates, changes in prepayment rates and other factors. Management determines the appropriate classification of securities at the time of purchase. The amortized cost of debt securities classified as securities held to maturity or securities available for sale is adjusted for amortization of premiums and accretion of discounts to maturity of the security using the interest method. Such amortization or accretion is included in interest on securities. Realized gains and losses are determined using the specific identification method and are included in noninterest income as securities gains (losses), net. Securities transferred from the available for sale category to the held to maturity category are recorded at fair value at the date of transfer. Unrealized holding gains or losses associated with the transfer of securities from available for sale to held to maturity are included in the balance of accumulated other comprehensive income (loss), net of tax, in the consolidated balance sheets. These unrealized holding gains or losses are amortized over the remaining life of the security as a yield adjustment in a manner consistent with the amortization or accretion of the original purchase premium or discount on the associated security. Trustmark reviews securities for impairment quarterly. Declines in the fair value of held to maturity and available for sale securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses to the extent the impairment is related to credit losses. The amount of the impairment related to other factors is recognized as a component of other comprehensive income (loss), net of tax. In estimating other-than-temporary impairment losses, Management considers, among other things, the length of time and the extent to which the fair value has been less than cost, the financial condition and near-term prospects of the issuer and Trustmark’s intent and ability to hold the security for a period of time sufficient to allow for any anticipated recovery in fair value.
Loans Held for Sale (LHFS)	Loans Held for Sale (LHFS) Primarily, all mortgage loans purchased from wholesale customers or originated in Trustmark’s General Banking Segment are considered to be held for sale. In certain circumstances, Trustmark will retain a mortgage loan in its portfolio based on banking relationships or certain investment strategies. Trustmark has elected to account for its LHFS under the fair value option permitted by Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 825, “Financial Instruments,” with interest income on the LHFS reported in interest and fees on LHFS and LHFI. Trustmark reports unrealized gains and losses resulting from changes in the fair value of the LHFS accounted for under the fair value option as noninterest income in mortgage banking, net. LHFS are actively managed and monitored and certain market risks of the loans may be mitigated through the use of derivatives. These derivative instruments are carried at fair value with changes in the fair value reported as noninterest income in mortgage banking, net. Changes in the fair value of the LHFS are largely offset by changes in the fair value of the derivative instruments. Election of the fair value option allows Trustmark to reduce the accounting volatility that would otherwise result from the asymmetry created by accounting for its LHFS at the lower of cost or fair value and the derivative instruments at fair value. Realized gains and losses upon ultimate sale of the loans are reported as noninterest income in mortgage banking, net. Government National Mortgage Association (GNMA) optional repurchase programs allow financial institutions to buy back individual delinquent mortgage loans that meet certain criteria from the securitized loan pool for which the institution provides servicing. At the servicer’s option and without GNMA’s prior authorization, the servicer may repurchase such a delinquent loan for an amount equal to 100 percent of the remaining principal balance of the loan. Under FASB ASC Topic 860, “Transfers and Servicing,” this buy-back option is considered a conditional option until the delinquency criteria are met, at which time the option becomes unconditional. When Trustmark is deemed to have regained effective control over these loans under the unconditional buy-back option, the loans can no longer be reported as sold and must be brought back onto the balance sheet as LHFS, regardless of whether Trustmark intends to exercise the buy-back option. These loans are reported as LHFS with the offsetting liability being reported as short-term borrowings. The fair value option election does not apply to the GNMA optional repurchase loans which do not meet the requirements under FASB ASC Topic 825 to be accounted for under the fair value option. Trustmark defers the upfront loan fees and costs related to the LHFS. In general, the LHFS are only retained on Trustmark’s balance sheet for 30 to 45 days before they are pooled and sold in the secondary market. The difference between deferring these loan fees and costs until the loans are sold and recognizing them in earnings as incurred as required by FASB ASC Subtopic 825-10 is considered immaterial. Deferred loan fees and costs are reflected in the basis of the LHFS and, as such, impact the resulting gain or loss when the loans are sold.
Loans Held for Investment (LHFI)	Loans Held for Investment (LHFI) LHFI are stated at the amount of unpaid principal, adjusted for the net amount of direct costs and nonrefundable loan fees associated with lending. The net amount of nonrefundable loan origination fees and direct costs associated with the lending process, including commitment fees, is deferred and accreted to interest income over the lives of the loans using a method that approximates the interest method. Interest on LHFI is accrued and recorded as interest income based on the outstanding principal balance. Past due LHFI are loans contractually past due 30 days or more as to principal or interest payments. A LHFI is classified as nonaccrual, and the accrual of interest on such loan is discontinued, when the contractual payment of principal or interest becomes 90 days past due on commercial credits and 120 days past due on non-business purpose credits. In addition, a credit may be placed on nonaccrual at any other time Management has serious doubts about further collectibility of principal or interest according to the contractual terms, even though the loan is currently performing. A LHFI may remain in accrual status if it is in the process of collection and well secured. When a LHFI is placed in nonaccrual status, interest accrued but not received is reversed against interest income. Interest payments received on nonaccrual LHFI are applied against principal under the cost-recovery method, until qualifying for return to accrual status. Under the cost-recovery method, interest income is not recognized until the principal balance is reduced to zero. LHFI are restored to accrual status when the obligation is brought current or has performed in accordance with the contractual terms for a reasonable period of time and the ultimate collectibility of the total contractual principal and interest is no longer in doubt. A LHFI is considered impaired when, based on current information and events, it is probable that Trustmark will be unable to collect all amounts due according to the contractual terms of the loan agreement. In accordance with FASB ASC Subtopic 310-40-35, “Troubled Debt Restructurings by Creditors: Subsequent Measurement,” all loans restructured in a troubled debt restructuring (TDR), without regard to a loan’s accrual status, are impaired loans. Additionally, Trustmark specifically reviews all commercial nonaccrual relationships of $500 thousand or more for impairment. Trustmark considers all commercial nonaccrual relationships of $500 thousand or more, which have been specifically reviewed for impairment and deemed impaired, and all LHFI classified as TDRs to be individually evaluated impaired LHFI. At the time a LHFI that has been specifically reviewed for impairment is deemed to be impaired, the full difference between book value and the most likely estimate of the collateral’s net realizable value is charged off or a specific reserve is established. As subsequent events dictate and estimated net realizable values change, further adjustments may be necessary. Commercial nonaccrual relationships under $500 thousand are not specifically reviewed for impairment due to the insignificant number and dollar amount of these types of loans. Nonaccrual LHFI includes both individually evaluated impaired LHFI as well as smaller balance homogeneous loans that are collectively evaluated for impairment. Consistent with the policy for nonaccrual LHFI, interest payments on impaired LHFI, with the exception of TDRs in accrual status, are applied to principal. Impaired LHFI, or portions thereof, are charged off when deemed uncollectible. Troubled Debt Restructuring A TDR occurs when a borrower is experiencing financial difficulties, and for related economic or legal reasons, a concession is granted to the borrower that Trustmark would not otherwise consider. Whatever the form of concession that might be granted by Trustmark, Management’s objective is to enhance collectibility by obtaining more cash or other value from the borrower or by increasing the probability of receipt by granting the concession than by not granting it. Other concessions may arise from court proceedings or may be imposed by law. In addition, TDRs also include those credits that are extended or renewed to a borrower who is not able to obtain funds from sources other than Trustmark at a market interest rate for new debt with similar risk. A formal TDR may include, but is not necessarily limited to, one or a combination of the following situations: • Trustmark accepts a third-party receivable or other asset(s) of the borrower, in lieu of the receivable from the borrower. • Trustmark accepts an equity interest in the borrower in lieu of the receivable. • Trustmark accepts modification of the terms of the debt including but not limited to: o Reduction (absolute or contingent) of the stated interest rate to below the current market rate. o Extension of the maturity date or dates at a stated interest rate lower than the current market rate for new debt with similar risk. o Reduction (absolute or contingent) of the face amount or maturity amount of the debt as stated in the note or other agreement. o Reduction (absolute or contingent) of accrued interest. Troubled debt restructurings are addressed in Trustmark’s loan policy, and in accordance with that policy, any modifications or concessions that may result in a TDR are subject to a special approval process which allows for control, identification, and monitoring of these arrangements. Prior to granting a concession, a revised borrowing arrangement is proposed which is structured so as to improve collectability of the loan in accordance with a reasonable repayment schedule with any loss promptly identified. It is supported by a thorough evaluation of the borrower’s financial condition and prospects for repayment under those revised terms. Other TDRs arising from renewals or extensions of existing debt are routinely identified through the processes utilized in the Problem Loan Committee and in the Credit Quality Review Committee. TDRs are subsequently reported to the Directors’ Credit Policy Committee on a quarterly basis and are disclosed in Trustmark’s consolidated financial statements in accordance with GAAP and regulatory reporting guidance. All loans whose terms have been modified in a troubled debt restructuring are evaluated for impairment under FASB ASC Topic 310, “Receivables.” Accordingly, Trustmark measures any loss on the restructuring in accordance with that guidance. A TDR in which Trustmark receives physical possession of the borrower’s assets, regardless of whether formal foreclosure or repossession proceedings take place, is accounted for in accordance with FASB ASC Subtopic 310-40. Thus, the loan is treated as if assets have been received in satisfaction of the loan and reported as a foreclosed asset. A TDR may be returned to accrual status if Trustmark is reasonably assured of repayment of principal and interest under the modified terms and the borrower has demonstrated sustained performance under those terms for a period of at least six months. Otherwise, the restructured loan must remain on nonaccrual.
Allowance for Loan Losses, LHFI	Allowance for Loan Losses, LHFI The allowance for loan losses, LHFI is established through provisions for estimated loan losses charged against net income. The allowance account is maintained at a level which is believed to be adequate by Management based on estimated probable losses within the LHFI portfolio. Evaluations of the portfolio and individual credits are inherently subjective, as they require estimates, assumptions and judgments as to the facts and circumstances of particular situations. Some of the factors considered, such as amounts and timing of future cash flows expected to be received, may be susceptible to significant change. Trustmark’s allowance methodology is based on guidance provided in Securities and Exchange Commission (SEC) Staff Accounting Bulletin (SAB) No. 102, “Selected Loan Loss Allowance Methodology and Documentation Issues,” as well as other regulatory guidance. The allowance for loan losses, LHFI consists of three components: (i) a historical valuation allowance determined in accordance with FASB ASC Topic 450, “Contingencies,” based on historical loan loss experience for LHFI with similar characteristics and trends, (ii) a specific valuation allowance determined in accordance with FASB ASC Topic 310 based on probable losses on specific LHFI and (iii) a qualitative risk valuation allowance determined in accordance with FASB ASC Topic 450 based on general economic conditions and other specific internal and external qualitative risk factors. Each of these components calls for estimates, assumptions and judgments as described below. Historical Valuation Allowance The historical valuation allowance is derived by application of a historical net loss percentage to the outstanding balances of LHFI contained in designated pools and risk rating categories. Pools are established by grouping credits that display similar characteristics and trends such as commercial LHFI for working capital purposes and non-working capital purposes, commercial purpose LHFI secured by real estate (which are further segregated into 1-4 family construction, non 1-4 family construction, land, lots and development, owner-occupied and nonowner - occupied categories), other commercial loans, 1-4 family LHFI, 1-4 family LHFI secured by junior liens and other consumer LHFI. Within these pools, LHFI are further segregated based on Trustmark’s internal credit risk rating process that evaluates, among other things: the obligor’s ability and willingness to pay, the value of underlying collateral, the ability of guarantors to meet their payment obligations, management experience and effectiveness, and the economic environment and industry in which the borrower operates. The historical net loss percentages, calculated on a quarterly basis, are proportionally distributed to each risk rate within loan groups based upon degree of risk. Using third-party default data, which is updated annually to incorporate the most recent year’s information, average cumulative issuer-weighted global default rates by alphanumeric rating are aggregated by Trustmark’s commercial loan risk rates. Management uses the long-term default rates to measure the relative risk across the risk rates while the 12-quarter quantitative loss rate sets the absolute level of allowance for loan loss reserve. Further, given the volatility in the default data, the longer look-back period provides for a more stable allowance for loan loss estimate which better reflects the incremental risk across the risk rates. The historical net loss percentages are calculated using a 12 quarter look-back period, which is the period that best reflects losses inherent in the current loan portfolio. The look-back period sufficiently captures the volatility in net charge-off rates from quarter to quarter and affects the qualitative adjustments that are required to capture the differences in conditions between the current period and those that were prevailing during the look-back period. The loss emergence period (LEP) refers to the period of time between the events that trigger a loss and charge-off of that loss. Losses are usually not immediately known and determining the loss event can be difficult. It takes time for the borrower and extent of loss to be identified and determined. Management may not be aware that the loss event has occurred until the borrower exhibits the inability to pay or other evidence of credit deterioration. The LEP is evaluated annually to incorporate the most recent year’s data and adjusted as necessary. Loans-Specific Valuation Allowance Once a LHFI is classified, it is subject to periodic review to determine whether or not the loan is impaired. If determined to be impaired, the loan is evaluated using one of the valuation criteria contained in FASB ASC Topic 310 (i.e., individually or collectively evaluated), and a specific valuation allowance is allocated, if necessary, so that the loan is reported at the net realizable value. Qualitative Risk Valuation Allowance The qualitative risk valuation allowance is based on general economic conditions and other internal and external factors affecting Trustmark as a whole as well as specific LHFI. Factors considered include the following within Trustmark’s five key market regions: the experience, ability, and effectiveness of Trustmark’s lending management and staff; adherence to Trustmark’s loans policies, procedures and internal controls; the volume of exceptions relating to collateral, underwriting and financial documentation; credit concentrations; recent performance trends; regional economic trends; the impact of recent acquisitions; and the impact of significant natural disasters. These factors are evaluated on a quarterly basis with the results representing Trustmark’s qualitative risk profile in the current period which is used to establish an appropriate allowance. The qualitative portion of the commercial and consumer LHFI allowance for loan loss methodology also incorporates the use of maximum observed gross historical losses observed through the last economic cycle as a way to calculate a maximum qualitative reserve limit. The maximum observed gross historical losses as a percentage of the loan balances results in a maximum observed gross historical loss rate. Once the quantitative component of the allowance for loan loss methodology is calculated, the quantitative reserve percentage is deducted from the maximum observed gross historical loss rate to determine the maximum possible qualitative reserve limit. Management uses its qualitative factor evaluation process in conjunction with this maximum to determine the appropriate estimate of the qualitative considerations not captured by Trustmark’s historical loss rates. Other factors included in the qualitative risk valuation allowance include consideration of: commercial loan facility risk that embodies the nature, frequency and duration of the repayment structure as it pertains to the actual source of loan repayment, commercial nonaccrual relationships under $500 thousand which are below the threshold to perform a specific impairment analysis, and independent consumer credit bureau scores that are monitored to identify shifts in risk that are represented in the retail portfolio. These factors are also evaluated on a quarterly basis with the exception of the commercial nonaccrual relationships under $500 thousand which are evaluated monthly. and credit card debt are generally charged off on or prior to 180 days of delinquency. LHFI are charged off against the allowance for loan losses, LHFI, with any subsequent recoveries credited back to the allowance account.
Acquired Loans	Acquired Loans Acquired loans are accounted for under the acquisition method of accounting. The acquired loans are recorded at their estimated fair value at the time of acquisition. The fair value of acquired loans is determined using a discounted cash flow model based on assumptions regarding the amount and timing of principal and interest payments, estimated prepayments, estimated default rates, estimated loss severity in the event of defaults and current market rates. Estimated credit losses are included in the determination of fair value; therefore, an allowance for loan losses is not recorded on the acquisition date. Trustmark accounts for acquired impaired loans under FASB ASC Subtopic 310-30, “Loans and Debt Securities Acquired with Deteriorated Credit Quality.” An acquired loan is considered impaired when there is evidence of credit deterioration since origination and it is probable at the date of acquisition that Trustmark would be unable to collect all contractually required payments. Acquired loans accounted for under FASB ASC Subtopic 310-30 are referred to as “acquired impaired loans.” Revolving credit agreements, such as home equity lines, and commercial leases are excluded from acquired impaired loan accounting requirements. For acquired impaired loans, Trustmark (i) calculates the contractual amount and timing of undiscounted principal and interest payments (the “undiscounted contractual cash flows”) and (ii) estimates the amount and timing of undiscounted expected principal and interest payments (the “undiscounted expected cash flows”). Under FASB ASC Subtopic 310-30, the difference between the undiscounted contractual cash flows and the undiscounted expected cash flows is the nonaccretable difference. The nonaccretable difference represents an estimate of the loss exposure of principal and interest related to the acquired impaired loan portfolio, and such amount is subject to change over time based on the performance of such loans. The excess of undiscounted expected cash flows at acquisition over the initial fair value of acquired impaired loans is referred to as the “accretable yield” and is recorded as interest income over the estimated life of the loans using the effective yield method if the timing and amount of the future cash flows is reasonably estimable. Under the effective yield method, the accretable yield is recorded as an accretion of interest income over the life of the loan. Trustmark aggregates certain acquired impaired loans into pools of loans with common credit risk characteristics such as loan type and risk rating. To establish accounting pools of acquired impaired loans, loans are first categorized by similar purpose, collateral and geographic region. Within each category, the acquired impaired loans are further segmented by ranges of risk determinants observed at the time of acquisition. For commercial loans, the primary risk determinant is the risk rating as assigned by Trustmark. For consumer loans, the risk determinants include delinquency, delinquency history and FICO scores. Statistical comparison of the pools reflect that each pool is comprised of acquired impaired loans generally of similar characteristics, including loan type, loan risk and weighted average life. Each pool is then reviewed for similarity of the pool constituents, including standard deviation of purchase price, weighted average life and concentration of the largest loans. Loan pools are initially booked at the aggregate fair value of the loan pool constituents, based on the present value of Trustmark's expected cash flows from the acquired impaired loans. An acquired impaired loan is removed from a pool of loans only if the loan is sold, foreclosed, payment is received in full satisfaction of the loan or the loan is fully charged off. The acquired impaired loan is removed from the pool at the carrying value. When an individual acquired impaired loan is removed from a pool of loans, the difference between its relative carrying amount and the cash, collateral (measured at fair value) or other assets received will be recognized as a gain or loss immediately in interest income on acquired loans and would not affect the effective yield used to recognize the accretable yield on the remaining pool. Certain acquired impaired loans are not pooled and are accounted for individually. Such acquired impaired loans are withheld from pools due to the inherent uncertainty of the timing and amount of their cash flows or because they are not a suitable similar constituent to the established pools. As required by FASB ASC Subtopic 310-30, Trustmark periodically re-estimates the expected cash flows to be collected over the life of the acquired impaired loans. If, based on current information and events, it is probable that Trustmark will be unable to collect all cash flows expected at acquisition plus additional cash flows expected to be collected arising from changes in estimate after acquisition, the acquired loans are considered impaired. The decrease in the expected cash flows reduces the carrying value of the acquired impaired loans as well as the accretable yield and results in a charge-off through the allowance for loan losses, acquired loans or the establishment of an allowance for loan losses, acquired loans with a charge to income through the provision for loan losses, acquired loans. If, based on current information and events, it is probable that there is a significant increase in the cash flows previously expected to be collected or if actual cash flows are significantly greater than cash flows previously expected, Trustmark will reduce any remaining allowance for loan losses, acquired loans established on the acquired impaired loans for the increase in the present value of cash flows expected to be collected. The increase in the expected cash flows for the acquired impaired loans over those originally estimated at acquisition increases the carrying value of the acquired impaired loans as well as the accretable yield. The increase in the accretable yield is recognized as interest income prospectively over the remaining life of the acquired impaired loans. The carrying value of acquired impaired loans is reduced by payments received, both principal and interest, and increased by the portion of the accretable yield recognized as interest income. Under FASB ASC Subt opic 310-30, acquired impaired loans are generally considered accruing and performing loans as the loans accrete interest income over the estimated life of the loan when expected cash flows are reasonably estimable. Accordingly, acquired impaired loans that are contractually past due are still considered to be accruing and performing loans as long as the estimated cash flows are received as expected. If the timing and amount of cash flows is not reasonably estimable, the loans may be classified as nonaccrual loans and interest income may be recognized on a cash basis or as a reduction of the principal amount outstanding.
Premises and Equipment, Net	Premises and Equipment, Net Premises and equipment are reported at cost, less accumulated depreciation and amortization. Depreciation is charged to expense over the estimated useful lives of the assets, which are up to thirty-nine years for buildings and three to ten years for furniture and equipment. Leasehold improvements are amortized over the terms of the respective leases or the estimated useful lives of the improvements, whichever is shorter. In cases where Trustmark has the right to renew the lease for additional periods, the lease term for the purpose of calculating amortization of the capitalized cost of the leasehold improvements is extended when Trustmark is “reasonably assured” that it will renew the lease. Depreciation and amortization expenses are computed using the straight-line method. Trustmark continually evaluates whether events and circumstances have occurred that indicate that such long-lived assets have become impaired. Measurement of any impairment of such long-lived assets is based on the fair values of those assets. Branch closures and purchased land held for future branch expansion for more than five years are evaluated to determine if the related land, buildings and building improvements should be transferred to assets held for sale in accordance with FASB ASC Topic 360, “Property, Plant and Equipment.” The property is transferred to assets held for sale at the lower of its carrying value or fair value less cost to sell. An impairment loss is recorded at the time of transfer if the carrying value of the assets exceeds the fair value. Impairment losses are recorded as non-interest expense in other expense.
Mortgage Servicing Rights (MSR)	Mortgage Servicing Rights (MSR) Trustmark recognizes as assets the rights to service mortgage loans based on the estimated fair value of the MSR when loans are sold and the associated servicing rights are retained. Trustmark has elected to account for the MSR at fair value. The fair value of the MSR is determined using discounted cash flow techniques benchmarked against third-party valuations. Estimates of fair value involve several assumptions, including the key valuation assumptions about market expectations of future prepayment rates, interest rates and discount rates which are provided by a third-party firm. Prepayment rates are projected using an industry standard prepayment model. The model considers other key factors, such as a wide range of standard industry assumptions tied to specific portfolio characteristics such as remittance cycles, escrow payment requirements, geographic factors, foreclosure loss exposure, VA no-bid exposure, delinquency rates and cost of servicing, including base cost and cost to service delinquent mortgages. Prevailing market conditions at the time of analysis are factored into the accumulation of assumptions and determination of servicing value. Trustmark economically hedges changes in the fair value of the MSR attributable to interest rates. See Note 1 – Significant Accounting Policies, “Derivative Financial Instruments – Derivatives Not Designated as Hedging Instruments” for information regarding these derivative instruments. Trustmark receives annual servicing fee income for loans serviced, which is recorded as noninterest income in mortgage banking, net. The fees are based on a contractual percentage of the outstanding principal or a fixed amount per loan and are recorded as income when earned. Late fees and ancillary fees related to loan servicing are not considered material.
Goodwill and Identifiable Intangible Assets	Goodwill and Identifiable Intangible Assets Trustmark accounts for goodwill and other intangible assets in accordance with FASB ASC Topic 350, “Intangibles – Goodwill and Other.” Goodwill, which represents the excess of cost over the fair value of the net assets of an acquired business, is not amortized but tested for impairment on an annual basis, which is October 1 for Trustmark, or more often if events or circumstances indicate that there may be impairment. Identifiable intangible assets are acquired assets that lack physical substance but can be distinguished from goodwill because of contractual or legal rights or because the assets are capable of being sold or exchanged either on their own or in combination with a related contract, asset or liability. Trustmark’s identifiable intangible assets primarily relate to core deposits, insurance customer relationships and borrower relationships. These intangibles, which have definite useful lives, are amortized on an accelerated basis over their estimated useful lives. In addition, these intangibles are evaluated for impairment whenever events and changes in circumstances indicate that the carrying amount should be reevaluated. Trustmark also purchased banking charters in order to facilitate its entry into the states of Florida and Texas. These identifiable intangible assets are being amortized on a straight-line method over 20 years.
Other Real Estate	Other Real Estate Other real estate includes assets that have been acquired in satisfaction of debt through foreclosure and is carried at the lower of cost or estimated fair value. Fair value is based on independent appraisals and other relevant factors. Valuation adjustments required at foreclosure are charged to the allowance for loan losses. Other real estate is revalued on an annual basis or more often if market conditions necessitate. An other real estate specific reserve may be recorded through other real estate expense for declines in fair value subsequent to foreclosure based on recent appraisals or changes in market conditions. Subsequent to foreclosure, losses on the periodic revaluation of the property are charged against an existing other real estate specific reserve or as noninterest expense in other real estate expense if a reserve does not exist. Costs of operating and maintaining the properties as well as gains or losses on their disposition are also included in other real estate expense as incurred. Improvements made to properties are capitalized if the expenditures are expected to be recovered upon the sale of the properties.
Leases	Leases ASU 2016-02, “Leases (Topic 842),” became effective for Trustmark on January 1, 2019. Trustmark adopted FASB ASC Topic 842 ASU 2018-11, “Leases (Topic 842): Targeted Improvements” Once Trustmark identifies and determines certain contracts are leases according to FASB ASC Topic 842, Trustmark classifies it as an operating or a finance lease and recognizes a right-of-use asset and a lease liability at the lease commencement date. The lease liability represents the present value of the lease payments that remain unpaid as of the commencement date and the right-of-use asset is the initial lease liability recognized for the lease plus any lease payments made to the lessor at or before the commencement date as well as any initial direct costs less any lease incentives received. Trustmark’s finance leases consist of building and equipment leases. Trustmark recognizes interest expense based on the discount rate of the lease as interest expense in other interest expense and recognizes depreciation expense on a straight-line basis over the lease term as noninterest expense in net occupancy – premises for building leases and in equipment expense for equipment leases. Trustmark amortizes the right-of-use asset over the life of the lease term on a straight-line basis. Trustmark’s lease liabilities are measured as the present value of the remaining lease payments throughout the lease term. Trustmark records its finance lease right-of-use assets in premises and equipment, net and its finance lease liabilities in other borrowings. Trustmark’s operating leases primarily consist of building and land leases. Trustmark recognizes lease rent expense on a straight-line basis over the term of the lease contract and records it as noninterest expense in net occupancy – premises for building and land leases and in equipment expense for equipment leases. Trustmark’s amortization of the right-of-use asset is the difference between the straight-line lease expense and the interest expense recognized on the lease liability during the period. Trustmark’s lease liabilities are measured as the present value of the remaining lease payments throughout the lease term. Trustmark’s leases typically have one or more renewal options included in the lease contract. Due to the nature of Trustmark’s leases, for leases with renewal options available, Trustmark considers the first renewal option as reasonably certain to renew and is therefore included in the measurement of the right-of-use assets and lease liabilities. In order to calculate its right-of-use assets and lease liabilities, FASB ASC Topic 842 requires Trustmark to use the rate of interest implicit in the lease when readily determinable. If the rate implicit in the lease is not readily determinable, Trustmark is required to use its incremental borrowing rate, which is the rate of interest Trustmark would have to pay to borrow on a collateralized basis over a similar term in a similar economic environment. Trustmark was able to determine the implicit interest rate for its equipment leases and used that rate as its discount rate. Since the implicit interest rate for most of its building and land leases were not readily determinable, Trustmark used its incremental borrowing rate. Trustmark’s short-term leases primarily include automated teller machines. For short-term leases, Trustmark recognizes lease expense on a straight-line basis over the lease term. As previously stated, Trustmark has elected not to include short-term leases on its balance sheet.
Federal Home Loan Bank (FHLB) and Federal Reserve Bank of Atlanta Stock	Federal Home Loan Bank (FHLB) and Federal Reserve Bank of Atlanta Stock Trustmark accounts for its investments in FHLB and Federal Reserve Bank of Atlanta stock in accordance with FASB ASC Subtopic 942-325, “Financial Services-Depository and Lending-Investments-Other.” FHLB and Federal Reserve Bank stock are equity securities that do not have a readily determinable fair value because its ownership is restricted and it lacks a market. FHLB and Federal Reserve Bank stock are carried at cost and evaluated for impairment . Trustmark’s investment in member bank stock is included in other assets in the accompanying consolidated balance sheets. At December 31, 2019 and 2018 , Trustmark’s investment in member bank stock totaled $ million and $ million, respectively. The carrying value of Trustmark’s member bank stock gave rise to no other-than-temporary impairment for the years ended December 31, 2019 , 2018 and 2017 .
Revenue from Contract with Customers	Revenue from Contracts with Customers Trustmark accounts for revenue from contracts with customers in accordance with FASB ASC Topic 606, “Revenue from Contracts with Customers,” which provides that revenue be recognized in a manner that depicts the transfer of goods or services to a customer in an amount that reflects the consideration Trustmark expects to be entitled to in exchange for those goods or services. Revenue from contracts with customers is recognized either over time in a manner that depicts Trustmark’s performance, or at a point in time when control of the goods or services are transferred to the customer. Trustmark’s noninterest income, excluding all of mortgage banking, net and securities gains (losses), net and portions of bank card and other fees and other income, are considered within the scope of FASB ASC Topic 606. Gains or losses on the sale of other real estate, which are included in Trustmark’s noninterest expense as other real estate expense, are also within the scope of FASB ASC Topic 606. General Banking Segment Service Charges on Deposit Accounts In general, deposit accounts represent contracts with customers with no fixed duration and can be terminated or modified by either party at any time without compensation to the other party. According to FASB ASC Topic 606, a contract that can be terminated by either party without compensation does not exist for periods beyond the then-current period. Therefore, deposit contracts are considered to renew day-to-day if not minute-to-minute. Deposit contracts have a single continuous or stand-ready service obligation whereby Trustmark makes customer funds available for use by the customer as and when the customer chooses as well as other services such as statement rendering and online banking. The specific services provided vary based on the type of deposit account. These services are not individually distinct, but are distinct as a group, and therefore, constitute a single performance obligation which is satisfied over time and qualifies as a series of distinct service periods. Trustmark receives a fixed service charge amount as consideration monthly for services rendered. The service charge amount varies based on the type of deposit account. Some of the service charge revenue is subject to refund provisions, which is variable consideration under the guidelines of FASB ASC Topic 606. Trustmark has elected the ‘as-invoiced’ practical expedient permitted under FASB ASC Topic 606 for recognition of service charge revenue. Therefore, revenue is recognized at the time and in the amount the customer is charged. The service charge revenue is presented net of refunded amounts on Trustmark’s consolidated statements of income. Services related to non-sufficient funds, overdrafts, excess account activity, stop payments, dormant accounts, etc. are considered optional purchases for a deposit contract because there is no performance obligation for Trustmark until the service is requested by the customer or the occurrence of a triggering event. Fees for these services are fixed amounts and are charged to the customer when the service is performed. Revenue is recognized at the time the customer is charged. Bank Card and Other Fees Revenue from contracts with customers in bank card and other fees includes income related to interchange fees and various other contracts which primarily consists of contracts with a single performance obligation that is satisfied at a point in time. Trustmark receives a fixed consideration amount once the performance obligation is completed for these contracts. Trustmark reports revenue from these contracts net of amounts refunded or due to a third party. As both a debit and credit card issuer, Trustmark receives an interchange fee for every card transaction completed by its customers with a merchant. Trustmark receives two types of interchange fees: point-of-sale transactions in which the customer must enter the PIN associated with the card to complete the transaction (a debit card transaction), and signature transactions in which the signature of the customer is required to complete the transaction (a credit card transaction). Trustmark, as the card issuing or settlement bank, has a contract (implied based on customary business practices) with the payment network in which Trustmark has a single continuous service obligation to make funds available for settlement of the card transaction. Trustmark’s service obligation is satisfied over time and qualifies as a series of distinct service periods. Trustmark receives interchange fees as consideration for services rendered in the amount established by the respective payment network. The interchange fees are established by the payment network based on the type of transaction and is posted on their website. Trustmark receives and records interchange fee revenue from the payment networks daily net of all fees and amounts due to the payment network. Other Income Revenue from contracts with customers in other income includes income related to cash management services and other contracts with a single performance obligation that is satisfied at a point in time. Trustmark receives a fixed consideration amount once the performance obligation is completed for these contracts. Trustmark reports revenue from these contracts net of amounts refunded or due to a third party. Trustmark provides cash management services through the delivery of various products and services offered to its business and municipal customers including various departments of state, city and local governments, universities and other non-profit entities. Similar to the deposit account contracts, the cash management contracts primarily represent contracts with customers with no fixed duration and can be terminated or modified by either party at any time without compensation to the other party. Therefore, cash management contracts are generally considered to renew day-to-day if not minute-to-minute. Cash management contracts have a single continuous or stand-ready service obligation whereby Trustmark makes a specific service or group of services available for use by the customer as and when the customer chooses. The specific services provided vary based on the type of account or product. These services are not individually distinct, but are distinct as a group, and therefore, constitute a single performance obligation which is satisfied over time and qualifies as a series of distinct service periods. Trustmark receives a set service charge or maintenance fee amount as consideration monthly for services rendered. However, some of the fees are based on the number of transactions that occur (i.e. flat fee for a set number of transactions per month then an additional charge for each transaction after that) or the average daily account balance maintained by the customer during the month and a small amount of the cash management fee revenue is subject to refund provisions. These fees represent variable consideration under the guidelines of FASB ASC Topic 606. Trustmark has elected the ‘as-invoiced’ practical expedient permitted under FASB ASC Topic 606 for recognition of cash management fee revenue. The cash management revenue is presented net of any refunded amounts on Trustmark’s consolidated statements of income. Trustmark’s merchant services provider contracts directly with Trustmark business customers and provides Trustmark’s merchant customers card processing equipment and transaction processing services. Trustmark’s contract with the merchant services provider has a single-continuous service obligation to provide customer referrals for potential new accounts which is satisfied over time and qualifies as a series of distinct service periods. Trustmark receives a flat fee for each new account established and a percentage of the residual income related to transactions processed for Trustmark’s merchant customers each month as provided in the contract. Under the guidelines of FASB ASC Topic 606, the fee received for each new account and the profit sharing represent variable consideration. Revenue from merchant card services contracts is recognized monthly using a time-elapsed measure of progress. Trustmark has elected the ‘as-invoiced’ practical expedient permitted under FASB ASC Topic 606 for recognition of the merchant card services revenue. Other Real Estate Trustmark records a gain or loss from the sale of other real estate when control of the property transfers to the buyer. Trustmark records the gain or loss from the sale of other real estate in noninterest expense as other real estate expense. Other real estate sales for the year ended December 31, 2019 resulted in net losses of $291 thousand compared to net gains of $700 thousand for the year ended December 31, 2018 and $2.1 million for the year ended December 31, 2017. In general, purchases of Trustmark’s other real estate property are not financed by Trustmark. Financing the purchase of other real estate is evaluated based upon the same lending policies and procedures as all other types of loans. Under FASB ASC Subtopic 610-20, “Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets,” when Trustmark finances the sale of its other real estate to a buyer, Trustmark is required to assess whether the buyer is committed to perform their obligations under the contract and whether collectability of the transaction price is probable. Once these two criteria are met, Trustmark derecognizes the other real estate asset and records a gain or loss on the sale once control of the property is transferred to the buyer. Wealth Management Segment Trust Management There are five categories of revenue included in trust management: personal trust and investments, retirement plan services, institutional custody, corporate trust and other. Each of these categories includes multiple types of contracts, service obligations and fee income. However, the majority of these contracts include a single service obligation that is satisfied over time, the customer is charged in arrears for services rendered and revenue is recognized when payment is received. In general, the time period between when the service obligation is completed and when payment from the customer is received is less than 30 days . Revenue from trust management contracts is primarily related to monthly service periods and based on the prior month-end’s market value. Some trust management revenue is mandated by a court order, while other revenue consists of flat fees. Trust management revenue based on an account’s market value represents variable consideration under the guidelines of FASB ASC Topic 606. Trustmark has elected the ‘as-invoiced’ practical expedient allowed under FASB ASC Topic 606 to account for the trust management revenue. Assets under administration held by Trustmark in a fiduciary or agency capacity for customers are not included in Trustmark’s consolidated balance sheets. Investment Services Investment services includes both brokerage and annuity income. Trustmark has a contract with a third-party investment services company which contains a single continuous service obligation, to provide broker-dealer and advisory services to customers on behalf of the third-party, which is satisfied over time and qualifies as a series of distinct service periods. Trustmark serves as the agent between the third-party investment services company, the principle, and the customer. In accordance with the contract, Trustmark receives a monthly payment from the investment services company for commissions and advisory fees (asset management fees) earned on transactions completed in the prior month net of all charges and fees due to the investment services company. Trustmark recognizes revenue from the investment services company, net of the revenue sharing expense due to the investment services company, when the payments are received. Commissions vary from month-to-month based on the specific products and transactions completed. The advisory fees vary based on the average daily balance of the managed assets for the period. The commissions and advisory fees represent variable consideration under FASB ASC Topic 606. Trustmark has elected the ‘as-invoiced’ practical expedient allowed under FASB ASC Topic 606 to recognize revenue from the investment services company. Insurance Segment Fisher Brown Bottrell Insurance, Inc. (FBBI), a wholly-owned subsidiary of Trustmark National Bank (TNB), operates as an insurance broker representing the policyholder and has no allegiance with any one insurance provider. FBBI serves as the agent between the insurance provider (either insurance carrier or broker), the principal, and the policy holder, the customer. FBBI has four general categories of insurance contracts: commercial, commercial installments, personal and employee benefits. FBBI’s insurance contracts contain a single performance obligation, policy placement, which is satisfied at a point in time. FBBI’s performance obligation is satisfied as of the policy effective date. In addition to policy placement, FBBI provides various other periodic services to the policyholders for which no additional fee is charged. These additional services are not considered material to the overall contract. Trustmark has elected the immaterial promises practical expedient allowed under FASB ASC Topic 606, which allows Trustmark to not assess whether promised services are performance obligations if the promised services are immaterial in the context of the contract. Therefore, the immaterial additional services offered to policyholders are not considered a performance obligation and no amount of the contract transaction price is allocated to these services. In general, the transaction price for the insurance contracts is an established commission amount agreed upon by FBBI and the insurance provider. The commission amount varies based on the insurance provider and the type of policy. There are a small number of insurance contracts which FBBI does not receive a commission, but charges a fee directly to the policyholder. Most of the commissions from insurance contracts are subject to clawback provisions which require FBBI to refund a prorated amount of the commissions received as a result of policy cancellations or lapses. Commissions subject to clawback provisions are considered variable consideration under FASB ASC Topic 606. Trustmark believes the expected value method of estimating the commissions subject to clawback provisions would best predict the amount of commissions FBBI will be entitled to because of the large number of insurance contracts with similar characteristics and the number of possible outcomes. FBBI calculates a separate weighted-average percentage (returned commissions percentage) based on actual cancellations over the previous three years for commercial lines, bonds, and personal lines. FBBI applies the respective returned commissions percentage to the commission revenue earned related to insurance contracts within these three lines each month to calculate the estimated returned commissions amount, which represents the variable consideration subject to variable constraint. Revenue from insurance contracts is reported net of the variable consideration subject to variable constraint. FBBI performs an analysis of the returned commissions reserve quarterly and adjusts the reserve balance based on all available information including actual cancellations and the remaining term of the contract. The returned commission percentage is updated annually. Insurance Producers at FBBI earn commission as compensation for each policy they are responsible for placing. Commissions are not paid to Producers immediately at the policy effective date, can be subject to clawback provisions and can vary by Producer. Effective April 1, 2018, FBBI implemented a ‘pay when paid’ system. Under the ‘pay when paid’ system, Producers receive the commissions for which they are entitled at the end of the month following the month in which FBBI receives payment from the insurance provider or customer. Under FASB ASC Subtopic 340-40, “Other Assets and Deferred Costs: Contracts with Customers,” the commission paid to the Producers is an incremental cost of obtaining a contract, which should be capitalized and amortized in a manner consistent with the pattern of transfer of the service related to the contract acquisition asset. Insurance contracts have a term of one year or less; therefore, Trustmark has elected the cost of obtaining a contract practical expedient allowed under FASB ASC Subtopic 340-40, which allows FBBI to recognize the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the contract asset that FBBI otherwise would have recognized is one year or less. Commission expense is recorded as noninterest expense in salaries and employee benefits when paid to the Producers. Commercial Insurance Revenue from FBBI’s commercial insurance contracts (both agency billed and direct billed) consists of a set commission amount, which is subject to clawback provisions. Revenue from commercial installment insurance contracts consists of a set commission amount, which is not subject to clawback provisions. An estimated commission amount is entered in the agency management system when a commercial insurance contract is placed. FBBI records a top line receivable based on the estimated commission amount entered in the system each month, along with a corresponding amount recognized as revenue, and then adjusts the estimated receivable when the commissions are received from the insurance provider or customer. Personal Insurance Revenue from FBBI’s personal insurance contracts consists of a set commission amount, which is subject to clawback provisions, and is recognized when payment is received (generally 30-60 days after the policy effective date). Personal insurance contracts have a term of one year; therefore, recognizing the revenue from these contracts when payment is received is not materially different than recognizing the revenue at the policy effective date for any given period. Employee Benefits Insurance Revenue from FBBI’s employee benefits insurance contracts consists of a variable commission amount, which is not subject to clawback provisions, and is recognized when payment is received, typically on a monthly basis. Employee benefits insurance contracts have a set commission rate, but can vary from period to period based on changes in the number of employees covered by the policy (i.e. new hires and terminations). FBBI generally receives twelve monthly commission payments for these contracts with the initial payment being received approximately 60-90 days after the policy effective date. Under the guidelines of FASB ASC Topic 606, commissions from employee benefits insurance contracts represent fixed consideration because at contract inception (policy effective date) there is a set commission rate times a known number of covered employees. Changes in the number of covered employees are not known, nor can they be predicted, at contract inception. An increase or decrease in the number of covered employees after the policy effective date is considered a contract modification resulting from a change in scope and transaction price under FASB ASC Topic 606. This modification is treated as part of the existing contract because it does not add a distinct service. Employee benefits insurance contracts have a term of one year; therefore, recognizing the revenue from these contracts when payment is received is not materially different than recognizing the revenue at the policy effective date or the contract modification date for any given period. Contingency Commission Insurance In addition to the insurance contracts discussed above, FBBI has contracts with various insurance providers for which it receives contingency income based on volume of business and claims experience. FBBI is the principal and the insurance provider is the customer for these contingency commission insurance contracts. The contingency commission contracts have a single continuous or stand-ready service obligation whereby FBBI places policies with policyholders when acceptable to the insurance provider, which is satisfied over time. The contract term for these contingency commission contracts is one year. Revenue is recognized from the contingency commission contracts monthly using a time-elapsed measure of progress. FBBI accrues throughout the current year the amount of contingency commission income it expects to receive in the following year adjusted for a degree of uncertainty. FBBI updates a detail by insurance provider with the contingency commission income received, which is then compared to the total amount that was expected to be received. If actual receipts are higher or lower than the amount accrued in the prior year, the monthly accrual for the current year is adjusted accordingly. Under the guidelines of FASB ASC Topic 606, revenue from contingency commission insurance contracts represents variable consideration and should be estimated using one of the two allowable methods subject to the variable consideration constraint. FBBI believes the most likely amount method to be the most appropriate method for estimating the variable consideration as there are only a few possible outcomes for each contract.
Derivative Financial Instruments	Derivative Financial Instruments Trustmark maintains an overall interest rate risk management strategy that incorporates the use of derivative instruments to minimize significant unplanned fluctuations in earnings and cash flows caused by interest rate volatility. Trustmark’s interest rate risk management strategy involves modifying the repricing characteristics of certain assets and liabilities so that changes in interest rates do not adversely affect the net interest margin and cash flows. Under the guidelines of FASB ASC Topic 815, “Derivatives and Hedging,” all derivative instruments are required to be recognized as either assets or liabilities and carried at fair value on the balance sheet. The fair value of derivative positions outstanding is included in other assets and/or other liabilities in the accompanying consolidated balance sheets and in the net change in these financial statement line items in the accompanying consolidated statements of cash flows as well as included in noninterest income in the accompanying consolidated statements of income and other comprehensive income (loss), net of tax in the accompanying consolidated statements of comprehensive income. Trustmark’s interest rate swap derivative instruments are subject to master netting agreements, and therefore, eligible for offsetting in the consolidated balance sheets. Trustmark has elected to not offset any derivative instruments in its consolidated balance sheets. Derivatives Designated as Hedging Instruments Trustmark entered into a forward interest rate swap contract on its junior subordinated debentures, with the objective of protecting the quarterly interest payments from the risk of variability of those payments resulting from changes in the three-month LIBOR interest rate, for the five-year Derivatives Not Designated as Hedging Instruments As part of Trustmark’s risk management strategy in the mortgage banking area, derivative instruments such as forward sales contracts are utilized. Trustmark’s obligations under forward contracts consist of commitments to deliver mortgage loans, originated and/or purchased, in the secondary market at a future date. Changes in the fair value of these derivative instruments are recorded as noninterest income in mortgage banking, net and are offset by changes in the fair value of LHFS. See Note 1 – Significant Accounting Policies, “Loans Held for Sale (LHFS)” for information regarding the fair value option election. Trustmark also utilizes derivative instruments such as interest rate lock commitments in its mortgage banking area. Rate lock commitments are residential mortgage loan commitments with customers, which guarantee a specified interest rate for a specified time period. Changes in the fair value of these derivative instruments are recorded as noninterest income in mortgage banking, net and are offset by the changes in the fair value of forward sales contracts. Trustmark utilizes a portfolio of exchange-traded derivative instruments, such as Treasury note futures contracts and option contracts, to achieve a fair value return that economically hedges changes in the fair value of the MSR attributable to interest rates. These transactions are considered freestanding derivatives that do not otherwise qualify for hedge accounting. These exchange-traded derivative instruments are accounted for at fair value with changes in the fair value recorded as noninterest income in mortgage banking, net and are offset by changes in the fair value of the MSR. The MSR fair value represents the present value of future cash flows, which among other things includes decay and the effect of changes in interest rates. Ineffectiveness of hedging the MSR fair value is measured by comparing the change in the fair value of the hedge instruments to the change in the fair value of the MSR asset attributable to changes in interest rates and other market driven changes in valuation inputs and assumptions. Trustmark offers certain derivatives products directly to qualified commercial lending clients seeking to manage their interest rate risk. Trustmark economically hedges interest rate swap transactions executed with commercial lending clients by entering into offsetting interest rate swap transactions with institutional derivatives market participants. Derivative transactions executed as part of this program are not designated as qualifying hedging relationships and are, therefore, carried at fair value with the change in fair value recorded as noninterest income in bank card and other fees. Because these derivatives have mirror-image contractual terms, in addition to collateral provisions which mitigate the impact of non-performance risk, the changes in fair value are expected to substantially offset.
Income Taxes	Income Taxes Trustmark accounts for uncertain tax positions in accordance with FASB ASC Topic 740, “Income Taxes,” which clarifies the accounting and disclosure for uncertainty in tax positions. Under the guidance of FASB ASC Topic 740, Trustmark accounts for deferred income taxes using the liability method. Deferred tax assets and liabilities are based on temporary differences between the financial statement carrying amounts and the tax basis of Trustmark’s assets and liabilities. Deferred tax assets and liabilities are measured using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be realized or settled and are presented net in the accompanying consolidated balance sheets in other assets.
Stock-Based Compensation	Stock-Based Compensation Trustmark accounts for the stock and incentive compensation under the provisions of FASB ASC Topic 718, “Compensation – Stock Compensation.” Under this accounting guidance, fair value is established as the measurement objective in accounting for stock awards and requires the application of a fair value based measurement method in accounting for compensation cost, which is recognized over the requisite service period. Trustmark has elected to account for forfeitures of stock awards as they occur.
Statements of Cash Flows	Statements of Cash Flows For purposes of reporting cash flows, cash and cash equivalents include cash on hand and amounts due from banks. The following table reflects specific transaction amounts for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Income taxes paid $ 24,809 $ 12,435 $ 7,371 Interest paid on deposits and borrowings 83,997 66,358 41,472 Noncash transfers from loans to other real estate 8,598 12,115 8,760 Investment in tax credit partnership not funded 5,000 — — Financing right-of-use assets resulting from lease liabilities 9,326 — — Operating right-of-use assets resulting from lease liabilities 31,182 — — Transfer of long-term FHLB advances to short-term — — 250,038 Assets acquired in business combination — — 196,265 Liabilities assumed in business combination — — 184,949
Per Share Data	Per Share Data Trustmark accounts for per share data in accordance with FASB ASC Topic 260, “Earnings Per Share,” which provides that unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are participating securities and shall be included in the computation of earnings per share (EPS) pursuant to the two-class method. Trustmark has determined that its outstanding unvested stock awards are not participating securities. Based on this determination, no change has been made to Trustmark’s current computation for basic and diluted EPS. Basic EPS is computed by dividing net income by the weighted-average shares of common stock outstanding. Diluted EPS is computed by dividing net income by the weighted-average shares of common stock outstanding, adjusted for the effect of potentially dilutive stock awards outstanding during the period. The following table reflects weighted-average shares used to calculate basic and diluted EPS for the periods presented (in thousands): Years Ended December 31, 2019 2018 2017 Basic shares 64,630 67,505 67,727 Dilutive shares 142 154 160 Diluted shares 64,772 67,659 67,887 Weighted-average antidilutive stock awards were excluded in determining diluted EPS. The following table reflects weighted-average antidilutive stock awards for the periods presented (in thousands): Years Ended December 31, 2019 2018 2017 Weighted-average antidilutive stock awards — 1 74
Fair Value Measurements	Fair Value Measurements FASB ASC Topic 820, “Fair Value Measurements and Disclosures,” defines fair value, establishes a framework for measuring fair value in generally accepted accounting principles, and requires certain disclosures about fair value measurements. The fair value of an asset or liability is the price that would be received to sell that asset or paid to transfer that liability in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. Depending on the nature of the asset or liability, Trustmark uses various valuation techniques and assumptions when estimating fair value. Inputs to valuation techniques include the assumptions that market participants would use in pricing an asset or liability. FASB ASC Topic 820 establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows: Level 1 Inputs – Valuation is based upon quoted prices (unadjusted) in active markets for identical assets or liabilities that Trustmark has the ability to access at the measurement date. Level 2 Inputs – Valuation is based upon quoted prices in active markets for similar assets or liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability such as interest rates, yield curves, volatilities and default rates and inputs that are derived principally from or corroborated by observable market data. Level 3 Inputs – Unobservable inputs reflecting the reporting entity’s own determination about the assumptions that market participants would use in pricing the asset or liability based on the best information available. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the fair value measurement in its entirety is classified is based on the lowest level input that is significant to the fair value measurement in its entirety. Trustmark’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability. Transfers between levels of the fair value hierarchy are recognized on the actual date of the event or circumstances that caused the transfer.
Accounting Policies Recently Adopted and Pending Accounting Pronouncements	Accounting Policies Recently Adopted Except for the changes detailed below, Trustmark has consistently applied its accounting policies to all periods presented in the accompanying consolidated financial statements. ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.” Issued in August 2017, ASU 2017-12 aims to improve the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements. The amendments in ASU 2017-12 aim to better align an entity’s risk management activities and financial reporting for hedging relationships by expanding and refining hedge accounting for both non-financial and financial risk components and aligning the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. The amendments in ASU 2017-12 (i) permit hedge accounting for risk components in hedging relationships involving nonfinancial risk and interest rate risk; (ii) change the guidance for designating fair value hedges of interest rate risk and for measuring the change in fair value of the hedged item in fair value hedges of interest rate risk; (iii) continue to allow an entity to exclude option premiums and forward points from the assessment of hedge effectiveness; and (iv) permit an entity to exclude the portion of the change in fair value of a currency swap that is attributable to a cross-country basis spread from the assessment of hedge effectiveness. The amendments of ASU 2017-12 also include targeted improvements intended to simplify the application of hedge accounting. All transition requirements and elections must be applied to all hedging relationships existing at the date of adoption. The amendments of ASU 2017-12 became effective for Trustmark on January 1, 2019. ASU 2017-12 did not have any impact to Trustmark’s existing hedging relationships at adoption; therefore, the adoption of ASU 2017-12 did not 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 became effective for Trustmark on January 1, 2019. Trustmark’s total unamortized premium for purchased debt securities within the scope of ASU 2017-08 is immaterial; therefore, the adoption of ASU 2017-08 did not have a material impact on Trustmark’s consolidated financial statements. 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, among other things, requires 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. In July 2018, the FASB issued ASU 2018-10, “Codification Improvements to Topic 842: Leases,” which provides corrections or improvements to a number of areas within FASB ASC Topic 842 and has the same transition guidance and effective date as ASU 2016-02. The FASB also issued ASU 2018-11, “Leases (Topic 842)-Targeted Improvements”, in July 2018, which provides entities with an additional and optional transition method to adopt the new lease standard and, for lessors only, a practical expedient, by class of underlying asset, to not separate non-lease components from the associated lease component. The amendments in ASU 2018-11 allow an entity the option to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption as opposed to at the beginning of the earliest period presented in the financial statements. The amendments of ASU 2018-11 have the same effective date as ASU 2016-02. In December 2018, the FASB issued ASU 2018-20, “Leases (Topic 842): Narrow-Scope Improvements for Lessors,” which provides targeted improvements and clarification to guidance with FASB ASC Topic 842 specific to lessors. The amendments of ASU 2018-20 have the same effective date as ASU 2016-02 and may be applied either retrospectively or prospectively to all new and existing leases. Trustmark has an immaterial amount of leases in which it is the lessor and adoption of ASU 2016-02 did not have a material impact to these leases or the related income. Trustmark obtained a third-party software application which will provide lease contract maintenance and lease accounting under the guidelines of FASB ASC Topic 842. All existing lease contracts, with the exception of short-term leases, were loaded into the software application and reviewed by Management. The amendments of ASU 2016-02 and subsequently issued ASUs, which provided additional guidance and clarifications to various aspects of FASB ASC Topic 842, became effective for Trustmark on January 1, 2019. Trustmark adopted the amendments in this ASU using the optional transition method allowable under ASU 2018-11, and was not required to recognize any cumulative-effect adjustment to the opening balance of retained earnings. During the first quarter of 2019, Trustmark recorded operating lease right-of-use assets and operating lease liabilities of $ 33.9 million and $ 34.9 million, respectively, in its consolidation balance sheet. Additionally, Trustmark recorded finance lease right-of-use assets, net of accumulated depreciation, of $ 11.2 million in premises and equipment, net and finance lease liabilities of $ 11.2 million in other borrowings. Trustmark’s total lease right-of-use assets, net represented approximately 0.3 % of its total assets as of March 31, 2019; therefore, the adoption of ASU 2016-02 did not have a material impact on Trustmark’s consolidated financial statements. Disclosures required by the amendments of ASU 2016-02 are included in Note 11 – Leases of this report. Pending Accounting Pronouncements ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” Issued in December 2019, ASU 2019-12 seeks to simplify the accounting for income taxes by removing certain exceptions to the general principles in FASB ASC Topic 740, Income Taxes. In particular, the amendments of ASU 2019-12 remove the exceptions to (1) the incremental approach for intra-period tax allocation when there is a loss from continuing operations and income or a gain from other items (e.g., discontinued operations or other comprehensive income); (2) the requirement to recognize a deferred tax liability for equity method investments when a foreign subsidiary becomes an equity method investment; (3) the ability not to recognize a deferred tax liability for a foreign subsidiary when a foreign equity method investment becomes a subsidiary; and (4) the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. The amendments of ASU 2019-12 (1) require that an entity recognize a franchise tax (or similar tax), that is partially based on income, in accordance with FASB ASC Topic 740 and account for any incremental amount incurred as a non-income-based tax; (2) require that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should instead be considered a separate transaction; (3) specify that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements, but rather may elect to do so for a legal entity that is both not subject to tax and disregarded by the taxing authority; and (4) require that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date. ASU 2019-12 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption of ASU 2019-12 is permitted, including adoption in any interim period for periods for which financial statements have not yet been issued. An entity that elects to early adopt the amendments in an interim period should reflect any adjustments as of the beginning of the annual period that includes that interim period. Additionally, an entity that elects early adoption must adopt all the amendments in the same period. The amendments related to separate financial statements of legal entities that are not subject to tax should be applied on a retrospective basis for all periods presented. The amendments related to changes in ownership of foreign equity method investments or foreign subsidiaries should be applied on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The amendments related to franchise taxes that are partially based on income should be applied on either a retrospective basis for all periods presented or a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. All other amendments should be applied on a prospective basis. Trustmark intends to adopt the amendments in ASU 2019-12 during the first quarter of 2021. Adoption of ASU 2019-12 is not expected to have a material impact to Trustmark’s consolidated financial statements. ASU 2018-15, “Intangibles-Goodwill and Other–Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force).” Issued in August 2018, ASU 2018-15 aims to reduce complexity in the accounting for costs of implementing a cloud computing service arrangement. ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The amendments of ASU 2018-15 require an entity to follow the guidance in FASB ASC Subtopic 350-40, “Intangibles-Goodwill and Other-Internal-Use Software,” in order to determine which implementation costs to capitalize as an asset related to the service contract and which costs to expense. The amendments of ASU 2018-15 also require an entity to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement (i.e. the noncancellable period of the arrangement plus periods covered by (1) an option to extend the arrangement if the entity is reasonably certain to exercise that option, (2) an option to terminate the arrangement if the entity is reasonably certain not to exercise the option, and (3) an option to extend (or not to terminate) the arrangement in which exercise of the option is in the control of the vendor). ASU 2018-15 also requires an entity to present the expense related to the capitalized implementation costs in the same line item in the statement of income as the fees associated with the hosting element (service) of the arrangement, and to classify payments for capitalized implementation costs in the statement of cash flows in the same manner as payments made for fees associated with the hosting element. ASU 2018-15 became effective for Trustmark on January 1, 20 20 . Trustmark does not currently have any material amount of implementation costs related to hosting arrangements that are service contracts within the scope of this ASU; therefore, adoption of ASU 2018-15 did not impact to Trustmark’s consolidated financial statements. ASU 2018-14, “Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans.” Issued in August 2018, ASU 2018-14 modifies the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The amendments in ASU 2018-14 remove certain disclosure requirements that are no longer considered cost beneficial, clarify the specific requirements of disclosures and add disclosure requirements identified as relevant. T he amendments of ASU 2018-14 become effective for fiscal years beginning after December 15, 2020. Trustmark plans to adopt these amendments during the first quarter of 2021. Management is currently assessing all the potential impacts of the amendments in ASU 2018-14 on Trustmark’s consolidated financial statements; however, the adoption of ASU 2018-14 is not expected to have a material impact on Trustmark’s consolidated financial statements. ASU 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement.” Issued in August 2018, the amendments in this ASU remove disclosure requirements in FASB ASC Topic 820 related to (1) the amount of, and reasons for, transfers between Level 1 and Level 2 of the fair value hierarchy; (2) the policy for timing of transfers between levels; (3) the valuation processes for Level 3 fair value measurements; and (4) for non-public entities, the changes in unrealized gains and losses for the period included in earnings for recurring Level 3 fair value measurements held at the end of the reporting period. The ASU also modifies disclosure requirements such that (1) in place of a rollforward for Level 3 fair value measurements, a non-public entity is required to disclose transfers into and out of Level 3 of the fair value hierarchy and purchases and issues of Level 3 assets and liabilities; (2) for investments in certain entities that calculate net asset value, an entity is required to disclose the timing of liquidation of an investee’s assets and the date that restrictions from redemption might lapse, only if the investee has communicated the timing to the entity or announced the timing publicly; and (3) it is clear that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date. Additionally, this ASU adds disclosure requirements for public entities about (1) the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period, and (2) the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The amendments of ASU 2018-13 became effective for Trustmark on January 1, 2020. Adoption of ASU 2018-13 did not have a material impact on Trustmark’s consolidated financial statements, and changes to disclosures as required by the amendments of ASU 2018-13 will be presented beginning with the Quarterly Report on Form 10-Q for the period ending March 31, 2020. 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 became effective for Trustmark on January 1, 2020, and the amendments of this ASU will be applicable to the annual goodwill impairment test performed as of October 1, 2020 . Based on Trustmark’s annual goodwill impairment test performed as of October 1, 201 9 , the fair value of its reporting units exceeded the carrying value and, therefore, the related goodwill was not impaired. T he adoption of ASU 2017-04 is not expected to have a material impact on Trustmark’s consolidated financial statements. 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, and all subsequent ASUs issued by FASB to provide additional guidance and clarification related to this Topic, became effective for Trustmark on January 1, 2020. As previously disclosed, Trustmark established a cross-functional Current Expected Credit Loss (CECL) Steering Committee, a CECL Solution Development Working Group and a CECL Working Group which included the appropriate members of Management to evaluate the impact this ASU, and all subsequent ASUs issued by FASB, 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 these ASUs as well as any resources needed to implement the amendments. Trustmark selected a third-party vendor to provide allowance for loan loss software as well as advisory services in developing a new methodology that would be compliant with amendments of ASU 2016-13, and is working with the approved third-party vendor to finalize the impact to Trustmark. Based upon preliminary modeling results, Management estimates the allowance related to loans will increase. Trustmark expects to recognize a one-time cumulative effect adjustment through retained earnings at the date of adoption. Trustmark intends to estimate losses over an approximate one-year forecast period using Moody’s baseline economic forecasts, and then revert to longer term historical loss experience over a one-year period to estimate losses. Currently, Trustmark expects the increase in the allowance to be in the range of $10.0 million to $35.0 million, primarily driven by unfunded commitment exposure, economic forecasts and uncertainty. This estimated range includes a qualitative adjustment to the allowance for credit losses related to loans and an allowance on unfunded loan commitments. The estimate is subject to further refinement based on continuing reviews and testing of Management’s judgements, current and forecasted macroeconomic conditions and the composition of the loan portfolio, as well as finalization of internal controls to ensure model effectiveness. Trustmark does not expect a material allowance for credit losses to be recorded on held-to-maturity securities under the CECL model due to the composition of the portfolio being primarily government agency-backed securities for which the risk of loss is minimal. Additionally, Trustmark does not expect a material allowance for credit losses to be recorded on available-for-sale debt securities, as the majority of the portfolio consists of government agency-backed securities for which the risk of loss is minimal. Disclosures required by the amendments ASU 2016-13 will be presented beginning with the Quarterly Report on Form 10-Q for the period ending March 31, 2020.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Cash Flows Supplementary Disclosures	For purposes of reporting cash flows, cash and cash equivalents include cash on hand and amounts due from banks. The following table reflects specific transaction amounts for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Income taxes paid $ 24,809 $ 12,435 $ 7,371 Interest paid on deposits and borrowings 83,997 66,358 41,472 Noncash transfers from loans to other real estate 8,598 12,115 8,760 Investment in tax credit partnership not funded 5,000 — — Financing right-of-use assets resulting from lease liabilities 9,326 — — Operating right-of-use assets resulting from lease liabilities 31,182 — — Transfer of long-term FHLB advances to short-term — — 250,038 Assets acquired in business combination — — 196,265 Liabilities assumed in business combination — — 184,949
Weighted-Average Shares Used to Calculate Basic and Diluted EPS	The following table reflects weighted-average shares used to calculate basic and diluted EPS for the periods presented (in thousands): Years Ended December 31, 2019 2018 2017 Basic shares 64,630 67,505 67,727 Dilutive shares 142 154 160 Diluted shares 64,772 67,659 67,887
Weighted-Average Antidilutive Stock Awards Excluded from Determining Diluted EPS	Weighted-average antidilutive stock awards were excluded in determining diluted EPS. The following table reflects weighted-average antidilutive stock awards for the periods presented (in thousands): Years Ended December 31, 2019 2018 2017 Weighted-average antidilutive stock awards — 1 74

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Dec. 31, 2019
Reliance [Member]
Business Acquisition [Line Items]
Summary of Estimated Fair Values of Assets Purchased and Liabilities Assumed	The statement of assets purchased and liabilities assumed in the Reliance merger is presented below at their estimated fair values as of the merger date of April 7, 2017 ($ in thousands): Assets: Cash and due from banks $ 5,013 Federal funds sold and securities purchased under reverse repurchase agreements 6,900 Securities 54,843 Acquired loans 117,447 Premises and equipment, net 3,700 Identifiable intangible assets 1,850 Other real estate 475 Other assets 6,037 Total Assets 196,265 Liabilities: Deposits 166,158 Other borrowings 17,469 Other liabilities 1,322 Total Liabilities 184,949 Net identified assets acquired at fair value 11,316 Goodwill 13,471 Total consideration paid $ 24,787

Securities Available for Sale_2

Securities Available for Sale and Held to Maturity (Tables)	12 Months Ended
	Dec. 31, 2019
Investments Debt And Equity Securities [Abstract]
Amortized Cost and Estimated Fair Value of Available for Sale and Held to Maturity Securities	The following tables are a summary of the amortized cost and estimated fair value of securities available for sale and held to maturity at December 31, 2019 and 2018 ($ in thousands): Securities Available for Sale Securities Held to Maturity Gross Gross Estimated Gross Gross Estimated Amortized Unrealized Unrealized Fair Amortized Unrealized Unrealized Fair December 31, 2019 Cost Gains Losses Value Cost Gains Losses Value U.S. Government agency obligations $ 22,965 $ 69 $ (707 ) $ 22,327 $ 3,781 $ 220 $ — $ 4,001 Obligations of states and political subdivisions 24,952 513 — 25,465 31,781 434 (53 ) 32,162 Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 69,196 425 (369 ) 69,252 10,820 266 (10 ) 11,076 Issued by FNMA and FHLMC 714,350 2,171 (3,165 ) 713,356 96,631 286 (370 ) 96,547 Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 656,162 3,777 (1,713 ) 658,226 485,324 7,026 (656 ) 491,694 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 113,359 625 (206 ) 113,778 109,762 1,042 (82 ) 110,722 Total $ 1,600,984 $ 7,580 $ (6,160 ) $ 1,602,404 $ 738,099 $ 9,274 $ (1,171 ) $ 746,202 December 31, 2018 U.S. Government agency obligations $ 31,235 $ 109 $ (1,009 ) $ 30,335 $ 3,736 $ 78 $ — $ 3,814 Obligations of states and political subdivisions 50,503 200 (27 ) 50,676 35,783 255 (139 ) 35,899 Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 69,648 147 (2,301 ) 67,494 12,090 45 (257 ) 11,878 Issued by FNMA and FHLMC 685,520 127 (18,963 ) 666,684 115,133 43 (2,887 ) 112,289 Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 830,129 67 (18,595 ) 811,601 578,827 189 (15,441 ) 563,575 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 187,494 191 (2,662 ) 185,023 164,074 299 (2,095 ) 162,278 Total $ 1,854,529 $ 841 $ (43,557 ) $ 1,811,813 $ 909,643 $ 909 $ (20,819 ) $ 889,733
Securities with Gross Unrealized Losses, Segregated by Length of Impairment	The table below includes securities with gross unrealized losses segregated by length of impairment at December 31, 2019 and 2018 ($ in thousands): Less than 12 Months 12 Months or More Total Gross Gross Gross Estimated Unrealized Estimated Unrealized Estimated Unrealized December 31, 2019 Fair Value Losses Fair Value Losses Fair Value Losses U.S. Government agency obligations $ 6,585 $ (105 ) $ 12,886 $ (602 ) $ 19,471 $ (707 ) Obligations of states and political subdivisions — — 6,216 (53 ) 6,216 (53 ) Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 23,544 (107 ) 18,529 (272 ) 42,073 (379 ) Issued by FNMA and FHLMC 112,879 (230 ) 278,120 (3,305 ) 390,999 (3,535 ) Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 158,341 (738 ) 151,271 (1,631 ) 309,612 (2,369 ) Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 51,312 (167 ) 14,155 (121 ) 65,467 (288 ) Total $ 352,661 $ (1,347 ) $ 481,177 $ (5,984 ) $ 833,838 $ (7,331 ) December 31, 2018 U.S. Government agency obligations $ — $ — $ 25,045 $ (1,009 ) $ 25,045 $ (1,009 ) Obligations of states and political subdivisions 4,954 (9 ) 12,802 (157 ) 17,756 (166 ) Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 9,163 (54 ) 61,141 (2,504 ) 70,304 (2,558 ) Issued by FNMA and FHLMC 31,931 (172 ) 731,749 (21,678 ) 763,680 (21,850 ) Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 46,643 (110 ) 1,296,221 (33,926 ) 1,342,864 (34,036 ) Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 5,497 (37 ) 272,789 (4,720 ) 278,286 (4,757 ) Total $ 98,188 $ (382 ) $ 2,399,747 $ (63,994 ) $ 2,497,935 $ (64,376 )
Gains and Losses as a Result of Calls and Disposition of Securities	For the periods presented, gross realized gains or losses as a result of calls and dispositions of securities, as well as any associated proceeds, were as follows ($ in thousands): Years Ended December 31, Available for Sale 2019 2018 2017 Proceeds from calls and sales of securities $ — $ — $ 27,682 Gross realized gains — — 16 Gross realized losses — — (1 )
Contractual Maturities of Available for Sale and Held to Maturity Securities	The amortized cost and estimated fair value of securities available for sale and held to maturity at December 31, 2019, by contractual maturity, are shown below ($ in thousands). Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Securities Securities Available for Sale Held to Maturity Amortized Estimated Amortized Estimated Cost Fair Value Cost Fair Value Due in one year or less $ 22,480 $ 22,623 $ 5,071 $ 5,115 Due after one year through five years 1,598 1,614 30,491 31,048 Due after five years through ten years 2,561 2,513 — — Due after ten years 21,278 21,042 — — 47,917 47,792 35,562 36,163 Mortgage-backed securities 1,553,067 1,554,612 702,537 710,039 Total $ 1,600,984 $ 1,602,404 $ 738,099 $ 746,202

Loans Held for Investment (LH_2

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI (Tables)	12 Months Ended
	Dec. 31, 2019
Accounts Notes Loans And Financing Receivable Gross Allowance And Net [Abstract]
Loan Portfolio Held for Investment	At December 31, 2019 and 2018, LHFI consisted of the following ($ in thousands): December 31, 2019 2018 Loans secured by real estate: Construction, land development and other land $ 1,162,791 $ 1,056,601 Secured by 1-4 family residential properties 1,855,913 1,825,492 Secured by nonfarm, nonresidential properties 2,475,245 2,220,914 Other real estate secured 724,480 543,820 Commercial and industrial loans 1,477,896 1,538,715 Consumer loans 175,738 182,448 State and other political subdivision loans 967,944 973,818 Other loans 495,621 494,060 LHFI 9,335,628 8,835,868 Less allowance for loan losses, LHFI 84,277 79,290 Net LHFI $ 9,251,351 $ 8,756,578
Aging Analysis of Past Due and Nonaccrual LHFI by Loan Type	The following tables provide an aging analysis of past due and nonaccrual LHFI by loan type at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Past Due 90 Days Current 30-59 Days 60-89 Days or More (1) Total Nonaccrual Loans Total Loans secured by real estate: Construction, land development and other land $ 380 $ 256 $ — $ 636 $ 897 $ 1,161,258 $ 1,162,791 Secured by 1-4 family residential properties 5,254 940 211 6,405 16,810 1,832,698 1,855,913 Secured by nonfarm, nonresidential properties 1,698 — — 1,698 7,700 2,465,847 2,475,245 Other real estate secured 8 — — 8 1,032 723,440 724,480 Commercial and industrial loans 617 12 39 668 21,775 1,455,453 1,477,896 Consumer loans 2,208 380 392 2,980 108 172,650 175,738 State and other political subdivision loans 76 — — 76 4,079 963,789 967,944 Other loans 152 4 — 156 825 494,640 495,621 Total $ 10,393 $ 1,592 $ 642 $ 12,627 $ 53,226 $ 9,269,775 $ 9,335,628 (1) Past due 90 days or more but still accruing interest. December 31, 2018 Past Due 90 Days Current 30-59 Days 60-89 Days or More (1) Total Nonaccrual Loans Total Loans secured by real estate: Construction, land development and other land $ 284 $ — $ — $ 284 $ 2,218 $ 1,054,099 $ 1,056,601 Secured by 1-4 family residential properties 8,600 1,700 569 10,869 14,718 1,799,905 1,825,492 Secured by nonfarm, nonresidential properties 1,887 — — 1,887 9,621 2,209,406 2,220,914 Other real estate secured 197 99 — 296 927 542,597 543,820 Commercial and industrial loans 1,346 300 — 1,646 23,938 1,513,131 1,538,715 Consumer loans 1,800 353 287 2,440 205 179,803 182,448 State and other political subdivision loans 186 — — 186 8,595 965,037 973,818 Other loans 83 — — 83 1,402 492,575 494,060 Total $ 14,383 $ 2,452 $ 856 $ 17,691 $ 61,624 $ 8,756,553 $ 8,835,868 (1) Past due 90 days or more but still accruing interest.
Impaired Financing Receivables	At December 31, 2019 and 2018, individually evaluated for impaired LHFI consisted of the following ($ in thousands): December 31, 2019 LHFI Unpaid Wit h o With an Total Average Principal Allowance Allowance Carrying Related Recorded Balance Recorded Recorded Amount Allowance Investment Loans secured by real estate: Construction, land development and other land $ 926 $ 610 $ 16 $ 626 $ — $ 1,089 Secured by 1-4 family residential properties 6,513 2,104 3,360 5,464 35 4,713 Secured by nonfarm, nonresidential properties 7,295 1,462 5,255 6,717 2,355 8,096 Other real estate secured 69 — 68 68 — 158 Commercial and industrial loans 27,178 19,374 4,084 23,458 707 27,088 Consumer loans 22 — 21 21 — 11 State and other political subdivision loans 4,079 — 4,079 4,079 1,809 6,337 Other loans 1,207 — 784 784 553 1,033 Total $ 47,289 $ 23,550 $ 17,667 $ 41,217 $ 5,459 $ 48,525 December 31, 2018 LHFI Unpaid Wit h o With an Total Average Principal Allowance Allowance Carrying Related Recorded Balance Recorded Recorded Amount Allowance Investment Loans secured by real estate: Construction, land development and other land $ 1,794 $ 1,528 $ 24 $ 1,552 $ — $ 1,738 Secured by 1-4 family residential properties 4,951 95 3,868 3,963 39 4,328 Secured by nonfarm, nonresidential properties 8,282 6,728 2,748 9,476 413 8,898 Other real estate secured — — 248 248 — 124 Commercial and industrial loans 37,786 12,893 17,824 30,717 4,334 26,725 Consumer loans 2 — 2 2 — 6 State and other political subdivision loans 8,688 4,079 4,516 8,595 516 4,297 Other loans 1,418 230 1,052 1,282 1,052 804 Total $ 62,921 $ 25,553 $ 30,282 $ 55,835 $ 6,354 $ 46,920
Impact of Modifications Classified as Troubled Debt Restructurings	The following tables illustrate the impact of modifications classified as TDRs for the periods presented ($ in thousands): Year Ended December 31, 2019 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Secured by 1-4 family residential properties 19 $ 1,742 $ 1,738 Secured by nonfarm, nonresidential properties 1 5,055 5,055 Commercial and industrial loans 8 9,167 9,054 Consumer loans 2 30 30 Total 30 $ 15,994 $ 15,877 Year Ended December 31, 2018 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Construction, land development and other land 1 $ 22 $ 22 Secured by 1-4 family residential properties 23 2,102 1,660 Secured by nonfarm, nonresidential properties 2 1,780 1,780 Commercial and industrial loans 23 26,970 25,862 Consumer loans 3 4 4 Total 52 $ 30,878 $ 29,328 Year Ended December 31, 2017 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Construction, land development and other land 1 $ 341 $ 325 Secured by 1-4 family residential properties 22 1,478 1,487 Secured by nonfarm, nonresidential properties 1 426 426 Commercial and industrial loans 8 12,836 12,836 Other loans 1 556 556 Total 33 $ 15,637 $ 15,630
Troubled Debt Restructuring Subsequently Defaulted	The table below includes the balances at default for TDRs modified within the last 12 months for which there was a payment default during the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 TDRs that Subsequently Defaulted Number of Contracts Recorded Investment Number of Contracts Recorded Investment Number of Contracts Recorded Investment Construction, land development and other land loans — $ — 1 $ 22 — $ — Loans secured by 1-4 family residential properties 3 446 5 734 4 78 Commercial and industrial loans 7 192 6 15,178 3 9,526 Consumer loans 1 27 1 1 — — Total 11 $ 665 13 $ 15,935 7 $ 9,604
Troubled Debt Restructuring Related to Loans Held for Investment by Loan Type	The following tables detail LHFI classified as TDRs by loan type at December 31, 2019, 2018 and 2017 ($ in thousands): December 31, 2019 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 15 $ 15 Secured by 1-4 family residential properties 77 3,865 3,942 Secured by nonfarm, nonresidential properties — 5,176 5,176 Commercial and industrial loans 3,319 18,913 22,232 Consumer loans — 21 21 Other loans — 137 137 Total TDRs $ 3,396 $ 28,127 $ 31,523 December 31, 2018 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 24 $ 24 Secured by 1-4 family residential properties 743 3,125 3,868 Secured by nonfarm, nonresidential properties 1,734 395 2,129 Commercial and industrial loans 9,007 12,620 21,627 Consumer loans — 2 2 Other loans — 540 540 Total TDRs $ 11,484 $ 16,706 $ 28,190 December 31, 2017 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 199 $ 199 Secured by 1-4 family residential properties 51 3,140 3,191 Secured by nonfarm, nonresidential properties — 421 421 Commercial and industrial loans 53 19,434 19,487 Consumer loans — 17 17 Other loans 556 — 556 Total TDRs $ 660 $ 23,211 $ 23,871
Carrying Amount of Loans by Credit Quality Indicator	The tables below present LHFI by loan type and credit quality indicator at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Commercial LHFI Pass - Special Mention - Substandard - Doubtful - Categories Category 7 Category 8 Category 9 Subtotal Loans secured by real estate: Construction, land development and other land $ 1,075,146 $ — $ 15,726 $ 42 $ 1,090,914 Secured by 1-4 family residential properties 116,592 45 6,355 41 123,033 Secured by nonfarm, nonresidential properties 2,430,761 — 44,001 328 2,475,090 Other real estate secured 721,238 — 2,547 — 723,785 Commercial and industrial loans 1,407,837 909 68,262 888 1,477,896 Consumer loans — — — — — State and other political subdivision loans 957,948 4,650 5,346 — 967,944 Other loans 469,095 3,445 16,926 30 489,496 Total $ 7,178,617 $ 9,049 $ 159,163 $ 1,329 $ 7,348,158 Consumer LHFI Past Due Past Due Current 30-89 Days 90 Days or More Nonaccrual Subtotal Total LHFI Loans secured by real estate: Construction, land development and other land $ 71,413 $ 332 $ — $ 132 $ 71,877 $ 1,162,791 Secured by 1-4 family residential properties 1,710,930 5,922 211 15,817 1,732,880 1,855,913 Secured by nonfarm, nonresidential properties 155 — — — 155 2,475,245 Other real estate secured 695 — — — 695 724,480 Commercial and industrial loans — — — — — 1,477,896 Consumer loans 172,649 2,588 393 108 175,738 175,738 State and other political subdivision loans — — — — — 967,944 Other loans 6,125 — — — 6,125 495,621 Total $ 1,961,967 $ 8,842 $ 604 $ 16,057 $ 1,987,470 $ 9,335,628 December 31, 2018 Commercial LHFI Pass - Special Mention - Substandard - Doubtful - Categories 1-6 Category 7 Category 8 Category 9 Subtotal Loans secured by real estate: Construction, land development and other land $ 982,305 $ 75 $ 5,645 $ 203 $ 988,228 Secured by 1-4 family residential properties 123,191 216 2,731 229 126,367 Secured by nonfarm, nonresidential properties 2,182,106 1,250 37,025 473 2,220,854 Other real estate secured 537,958 323 4,610 — 542,891 Commercial and industrial loans 1,468,262 12,431 55,943 2,079 1,538,715 Consumer loans — — — — — State and other political subdivision loans 958,214 5,250 10,354 — 973,818 Other loans 460,568 17,842 10,323 49 488,782 Total $ 6,712,604 $ 37,387 $ 126,631 $ 3,033 $ 6,879,655 Consumer LHFI Past Due Past Due Current 30-89 Days 90 Nonaccrual Subtotal Total LHFI Loans secured by real estate: Construction, land development and other land $ 67,913 $ 124 $ — $ 336 $ 68,373 $ 1,056,601 Secured by 1-4 family residential properties 1,675,455 9,872 569 13,229 1,699,125 1,825,492 Secured by nonfarm, nonresidential properties 60 — — — 60 2,220,914 Other real estate secured 929 — — — 929 543,820 Commercial and industrial loans — — — — — 1,538,715 Consumer loans 179,802 2,153 288 205 182,448 182,448 State and other political subdivision loans — — — — — 973,818 Other loans 5,278 — — — 5,278 494,060 Total $ 1,929,437 $ 12,149 $ 857 $ 13,770 $ 1,956,213 $ 8,835,868
Change in Allowance for Loan Losses	The following tables detail the balance in the allowance for loan losses, LHFI allocated to each loan type segmented by the impairment evaluation methodology used at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ — $ 8,260 $ 8,260 Secured by 1-4 family residential properties 35 8,897 8,932 Secured by nonfarm, nonresidential properties 2,355 23,803 26,158 Other real estate secured — 4,024 4,024 Commercial and industrial loans 707 25,285 25,992 Consumer loans — 3,379 3,379 State and other political subdivision loans 1,809 420 2,229 Other loans 553 4,750 5,303 Total allowance for loan losses, LHFI $ 5,459 $ 78,818 $ 84,277 December 31, 2018 Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ — $ 7,390 $ 7,390 Secured by 1-4 family residential properties 39 8,602 8,641 Secured by nonfarm, nonresidential properties 413 21,963 22,376 Other real estate secured — 3,450 3,450 Commercial and industrial loans 4,334 23,025 27,359 Consumer loans — 2,890 2,890 State and other political subdivision loans 516 474 990 Other loans 1,052 5,142 6,194 Total allowance for loan losses, LHFI $ 6,354 $ 72,936 $ 79,290 Changes in the allowance for loan losses, LHFI were as follows for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Balance at beginning of period $ 79,290 $ 76,733 $ 71,265 Transfers (1) — 1,554 — Loans charged-off (14,481 ) (29,489 ) (21,147 ) Recoveries 8,671 12,499 11,521 Net (charge-offs) recoveries (5,810 ) (16,990 ) (9,626 ) Provision for loan losses, LHFI 10,797 17,993 15,094 Balance at end of period $ 84,277 $ 79,290 $ 76,733 (1) The allowance for loan losses balance related to the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions, which were transferred from acquired impaired loans to LHFI during 2018. The following tables detail changes in the allowance for loan losses, LHFI by loan type for the years ended December 31, 2019 and 2018 , respectively ($ in thousands): 2019 Balance January 1, Provision for Loan Losses Balance December 31, Charge-offs Recoveries Loans secured by real estate: Construction, land development and other land $ 7,390 $ (40 ) $ 894 $ 16 $ 8,260 Secured by 1-4 family residential properties 8,641 (531 ) 666 156 8,932 Secured by nonfarm, nonresidential properties 22,376 (322 ) 472 3,632 26,158 Other real estate secured 3,450 — 29 545 4,024 Commercial and industrial loans 27,359 (5,344 ) 1,257 2,720 25,992 Consumer loans 2,890 (2,278 ) 1,829 938 3,379 State and other political subdivision loans 990 — — 1,239 2,229 Other loans 6,194 (5,966 ) 3,524 1,551 5,303 Total allowance for loan losses, LHFI $ 79,290 $ (14,481 ) $ 8,671 $ 10,797 $ 84,277 2018 Balance January 1, Provision for Loan Losses Balance December 31, Transfers (1) Charge-offs Recoveries Loans secured by real estate: Construction, land development and other land $ 7,865 $ 584 $ (123 ) $ 1,124 $ (2,060 ) $ 7,390 Secured by 1-4 family residential properties 10,874 182 (1,629 ) 646 (1,432 ) 8,641 Secured by nonfarm, nonresidential properties 23,428 446 (1,184 ) 133 (447 ) 22,376 Other real estate secured 2,790 291 — 23 346 3,450 Commercial and industrial loans 22,851 46 (18,823 ) 5,410 17,875 27,359 Consumer loans 3,470 5 (2,089 ) 2,019 (515 ) 2,890 State and other political subdivision loans 789 — — — 201 990 Other loans 4,666 — (5,641 ) 3,144 4,025 6,194 Total allowance for loan losses, LHFI $ 76,733 $ 1,554 $ (29,489 ) $ 12,499 $ 17,993 $ 79,290
Summary Of LHFI Evaluated For Impairment	The following tables detail LHFI by loan type related to each balance in the allowance for loan losses, LHFI segregated by the impairment evaluation methodology used at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 LHFI Evaluated for Impairment Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ 626 $ 1,162,165 $ 1,162,791 Secured by 1-4 family residential properties 5,464 1,850,449 1,855,913 Secured by nonfarm, nonresidential properties 6,717 2,468,528 2,475,245 Other real estate secured 68 724,412 724,480 Commercial and industrial loans 23,458 1,454,438 1,477,896 Consumer loans 21 175,717 175,738 State and other political subdivision loans 4,079 963,865 967,944 Other loans 784 494,837 495,621 Total $ 41,217 $ 9,294,411 $ 9,335,628 December 31, 2018 LHFI Evaluated for Impairment Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ 1,552 $ 1,055,049 $ 1,056,601 Secured by 1-4 family residential properties 3,963 1,821,529 1,825,492 Secured by nonfarm, nonresidential properties 9,476 2,211,438 2,220,914 Other real estate secured 248 543,572 543,820 Commercial and industrial loans 30,717 1,507,998 1,538,715 Consumer loans 2 182,446 182,448 State and other political subdivision loans 8,595 965,223 973,818 Other loans 1,282 492,778 494,060 Total $ 55,835 $ 8,780,033 $ 8,835,868

Acquired Loans (Tables)

Acquired Loans (Tables)	12 Months Ended
	Dec. 31, 2019
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities [Abstract]
Schedule of Acquired Loans	At December 31, 2019 and 2018, acquired loans consisted of the following ($ in thousands): December 31, 2019 2018 Loans secured by real estate: Construction, land development and other land $ 4,771 $ 5,878 Secured by 1-4 family residential properties 17,525 22,556 Secured by nonfarm, nonresidential properties 38,206 47,979 Other real estate secured 3,946 8,253 Commercial and industrial loans 5,035 15,267 Consumer loans 520 1,356 Other loans 2,598 5,643 Acquired loans 72,601 106,932 Less allowance for loan losses, acquired loans 815 1,231 Net acquired loans $ 71,786 $ 105,701
Changes in the Carrying Value of Acquired Loans	The following table presents changes in the net carrying value of the acquired loans for the periods presented ($ in thousands): Acquired Impaired Acquired Not 310-30 (1) Carrying value, net at January 1, 2018 $ 179,570 $ 77,868 Transfers (2)(3) (26,497 ) (59,916 ) Accretion to interest income 9,514 1,019 Payments received, net (62,519 ) (16,234 ) Other (4) (26 ) 74 Change in allowance for loan losses, acquired loans 2,848 — Carrying value, net at December 31, 2018 102,890 2,811 Transfers (3) — (2,926 ) Accretion to interest income 5,532 115 Payments received, net (37,230 ) — Other (4) 178 — Change in allowance for loan losses, acquired loans 416 — Carrying value, net at December 31, 2019 $ 71,786 $ — (1) “Acquired Not ASC 310-30” loans consist of loans that are not in scope for FASB ASC Subtopic 310-30. (2) During 2018, Trustmark transferred the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions from acquired impaired loans to LHFI. (3) “Acquired Not ASC 310-30” loans transferred to LHFI due to the discount on these loans being fully amortized. (4) Includes miscellaneous timing adjustments as well as acquired loan terminations through foreclosure, charge-off and other terminations.
Changes in Accretable Yield of Acquired Loans	The following table presents changes in the accretable yield for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Accretable yield at beginning of period $ (17,722 ) $ (31,426 ) $ (38,918 ) Additions due to acquisition (1) — — (784 ) Accretion to interest income 5,532 9,514 14,924 Disposals, net 2,072 3,926 2,868 Transfers (2) — 5,874 — Reclassification from nonaccretable difference (3) (4,698 ) (5,610 ) (9,516 ) Accretable yield at end of period $ (14,816 ) $ (17,722 ) $ (31,426 ) (1) Accretable yield on loans acquired from Reliance on April 7, 2017. (2) During 2018, Trustmark transferred the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions from acquired impaired loans to LHFI. (3) Reclassifications from nonaccretable difference are due to lower loss expectations and improvements in expected cash flows.
Components of the Allowance for Loan Losses on Acquired Loans	The following tables present the components of the allowance for loan losses on acquired impaired loans for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Balance at beginning of period $ 1,231 $ 4,079 $ 11,397 Transfers (1) — (1,554 ) — Provision for loan losses, acquired loans 42 (1,005 ) (7,395 ) Net (charge-offs) recoveries (458 ) (289 ) 77 Balance at end of period $ 815 $ 1,231 $ 4,079 (1) The allowance for loan losses balance related to the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions, which were transferred from acquired impaired loans to LHFI during 2018.
Acquired Loans by Loan Type and Credit Quality Indicator	The tables below present the acquired loans by loan type and credit quality indicator at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Commercial Loans Pass - Special Mention - Substandard - Doubtful - Categories 1-6 Category 7 Category 8 Category 9 Subtotal Loans secured by real estate: Construction, land development and other land $ 4,022 $ — $ 192 $ — $ 4,214 Secured by 1-4 family residential properties 3,164 42 580 — 3,786 Secured by nonfarm, nonresidential properties 27,848 — 9,972 386 38,206 Other real estate secured 3,878 — 68 — 3,946 Commercial and industrial loans 3,419 — — 1,616 5,035 Consumer loans — — — — — Other loans 2,591 — 7 — 2,598 Total acquired loans $ 44,922 $ 42 $ 10,819 $ 2,002 $ 57,785 Consumer Loans Past Due Past Due Total Current 30-89 Days 90 Days or More Nonaccrual (1) Subtotal Acquired Loans Loans secured by real estate: Construction, land development and other land $ 463 $ 94 $ — $ — $ 557 $ 4,771 Secured by 1-4 family residential properties 12,843 615 281 — 13,739 17,525 Secured by nonfarm, nonresidential properties — — — — — 38,206 Other real estate secured — — — — — 3,946 Commercial and industrial loans — — — — — 5,035 Consumer loans 489 31 — — 520 520 Other loans — — — — — 2,598 Total acquired loans $ 13,795 $ 740 $ 281 $ — $ 14,816 $ 72,601 (1) Acquired loans not accounted for under FASB ASC Subtopic 310-30. December 31, 2018 Commercial Loans Pass - Special Mention - Substandard - Doubtful - Categories 1-6 Category 7 Category 8 Category 9 Subtotal Loans secured by real estate: Construction, land development and other land $ 4,923 $ 26 $ 278 $ — $ 5,227 Secured by 1-4 family residential properties 4,341 45 534 451 5,371 Secured by nonfarm, nonresidential properties 34,933 — 12,614 432 47,979 Other real estate secured 7,653 — 190 410 8,253 Commercial and industrial loans 6,560 — 6,942 1,765 15,267 Consumer loans — — — — — Other loans 4,027 — 1,616 — 5,643 Total acquired loans $ 62,437 $ 71 $ 22,174 $ 3,058 $ 87,740 Consumer Loans Past Due Past Due Total Current 30-89 Days 90 Days or More Nonaccrual (1) Subtotal Acquired Loans Loans secured by real estate: Construction, land development and other land $ 642 $ 5 $ 4 $ — $ 651 $ 5,878 Secured by 1-4 family residential properties 16,133 571 481 — 17,185 22,556 Secured by nonfarm, nonresidential properties — — — — — 47,979 Other real estate secured — — — — — 8,253 Commercial and industrial loans — — — — — 15,267 Consumer loans 1,346 10 — — 1,356 1,356 Other loans — — — — — 5,643 Total acquired loans $ 18,121 $ 586 $ 485 $ — $ 19,192 $ 106,932 (1) Acquired loans not accounted for under FASB ASC Subtopic 310-30 .
Aging Analysis of Past Due and Nonaccrual Acquired Loans, by Class	The following tables provide an aging analysis of contractually past due and nonaccrual acquired loans by loan type at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Past Due 30-59 Days 60-89 Days 90 Days or More (1) Total Nonaccrual (2) Current Loans Total Acquired Loans Loans secured by real estate: Construction, land development and other land $ 94 $ — $ 38 $ 132 $ — $ 4,639 $ 4,771 Secured by 1-4 family residential properties 696 131 366 1,193 — 16,332 17,525 Secured by nonfarm, nonresidential properties 36 — 851 887 — 37,319 38,206 Other real estate secured 1 — 52 53 — 3,893 3,946 Commercial and industrial loans — — — — — 5,035 5,035 Consumer loans 16 15 — 31 — 489 520 Other loans — — — — — 2,598 2,598 Total acquired loans $ 843 $ 146 $ 1,307 $ 2,296 $ — $ 70,305 $ 72,601 (1) Past due 90 days or more but still accruing interest. (2) Acquired loans not accounted for under FASB ASC Subtopic 310-30. December 31, 2018 Past Due 30-59 Days 60-89 Days 90 Days or More (1) Total Nonaccrual (2) Current Loans Total Acquired Loans Loans secured by real estate: Construction, land development and other land $ 5 $ — $ 87 $ 92 $ — $ 5,786 $ 5,878 Secured by 1-4 family residential properties 664 108 481 1,253 — 21,303 22,556 Secured by nonfarm, nonresidential properties 206 — 978 1,184 — 46,795 47,979 Other real estate secured 2 14 — 16 — 8,237 8,253 Commercial and industrial loans — — — — — 15,267 15,267 Consumer loans 1 9 — 10 — 1,346 1,356 Other loans — — — — — 5,643 5,643 Total acquired loans $ 878 $ 131 $ 1,546 $ 2,555 $ — $ 104,377 $ 106,932 (1) Past due 90 days or more but still accruing interest. (2) Acquired loans not accounted for under FASB ASC Subtopic 310-30.

Premises and Equipment, Net (Ta

Premises and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Premises and Equipment, Net	At December 31, 2019 and 2018, premises and equipment, net consisted of the following ($ in thousands): December 31, 2019 2018 Land $ 52,454 $ 52,779 Buildings and leasehold improvements 210,362 202,912 Furniture and equipment 174,257 169,652 Total cost of premises and equipment 437,073 425,343 Less accumulated depreciation and amortization 256,608 247,160 Premises and equipment, net 180,465 178,183 Financing lease right-of-use assets 9,326 — Assets held for sale — 485 Total premises and equipment, net $ 189,791 $ 178,668

Mortgage Banking (Tables)

Mortgage Banking (Tables)	12 Months Ended
	Dec. 31, 2019
Mortgage Banking [Abstract]
Schedule of Activity in the Mortgage Servicing Rights	The activity in the MSR is detailed in the table below for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 Balance at beginning of period $ 95,596 $ 84,269 Origination of servicing assets 16,711 15,759 Change in fair value: Due to market changes (21,078 ) 7,342 Due to runoff (11,835 ) (11,774 ) Balance at end of period $ 79,394 $ 95,596
Schedule of Mortgage Loans Sold and Serviced for Others	The table below details the mortgage loans sold and serviced for others at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 2018 Federal National Mortgage Association $ 4,411,914 $ 4,204,336 Government National Mortgage Association 2,652,782 2,537,238 Federal Home Loan Mortgage Corporation 73,134 71,343 Other 19,404 21,957 Total mortgage loans sold and serviced for others $ 7,157,234 $ 6,834,874

Goodwill and Identifiable Int_2

Goodwill and Identifiable Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill by segment	The table below illustrates goodwill by segment for the years ended December 31, 2019 and 2018 ($ in thousands): General Banking Insurance Total Balance as of January 1, 2018 $ 334,603 $ 45,024 $ 379,627 Adjustment during 2018 — — — Balance as of December 31, 2018 334,603 45,024 379,627 Adjustment during 2019 — — — Balance as of December 31, 2019 $ 334,603 $ 45,024 $ 379,627
Schedule of identifiable intangible assets	At December 31, 2019 and 2018, identifiable intangible assets consisted of the following ($ in thousands): December 31, 2019 December 31, 2018 Gross Accumulated Net Carrying Gross Carrying Accumulated Net Carrying Amount Amortization Amount Amount Amortization Amount Core deposit intangibles $ 87,674 $ 82,096 $ 5,578 $ 87,674 $ 78,353 $ 9,321 Insurance intangibles 14,171 12,655 1,516 13,824 12,348 1,476 Banking charters 1,325 1,076 249 1,325 1,010 315 Total $ 103,170 $ 95,827 $ 7,343 $ 102,823 $ 91,711 $ 11,112 The following table illustrates the carrying amounts and remaining weighted-average amortization periods of identifiable intangible assets as of December 31, 2019 ($ in thousands): Remaining Weighted- Average Net Carrying Amortization Amount Period in Core deposit intangibles $ 5,578 3.8 Insurance intangibles 1,516 12.9 Banking charters 249 3.7 Total $ 7,343 5.7

Other Real Estate (Tables)

Other Real Estate (Tables)	12 Months Ended
	Dec. 31, 2019
Other Real Estate And Foreclosed Assets [Abstract]
Changes and Gains (Losses), Net on Other Real Estate	For the periods presented, changes and gains (losses), net on other real estate were as follows ($ in thousands): Years Ended December 31, 2019 2018 2017 Balance at beginning of period $ 34,668 $ 43,228 $ 62,051 Additions (1) 8,598 12,115 9,235 Disposals (11,474 ) (19,802 ) (24,762 ) Write-downs (2,544 ) (873 ) (3,296 ) Balance at end of period $ 29,248 $ 34,668 $ 43,228 Gain (losses), net on the sale of other real estate included in other real estate expense $ (291 ) $ 700 $ 2,087 (1) For the year ended December 31, 2017, additions to other real estate included $475 thousand of other real estate acquired in the Reliance merger on April 7, 2017.
Other Real Estate, By Type of Property	At December 31, 2019 and 2018, other real estate by type of property consisted of the following ($ in thousands): December 31, 2019 2018 Construction, land development and other land properties $ 11,482 $ 16,206 1-4 family residential properties 3,453 4,983 Nonfarm, nonresidential properties 14,313 13,296 Other real estate properties — 183 Total other real estate $ 29,248 $ 34,668
Other Real Estate, By Geographic Location	At December 31, 2019 and 2018, other real estate by geographic location consisted of the following ($ in thousands): December 31, 2019 2018 Alabama $ 8,133 $ 6,873 Florida 5,877 8,771 Mississippi (1) 14,919 17,255 Tennessee (2) 319 1,025 Texas — 744 Total other real estate $ 29,248 $ 34,668 (1) Mississippi includes Central and Southern Mississippi Regions. (2) Tennessee includes Memphis, Tennessee and Northern Mississippi Regions.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Components of Net Lease Cost	The table below details the components of net lease cost for the period presented ($ in thousands): Year Ended December 31, 2019 Finance leases Amortization of right-of-use assets $ 2,162 Interest on lease liabilities 307 Operating lease cost 5,183 Short-term lease cost 370 Variable lease cost 1,387 Sublease income (331 ) Net lease cost $ 9,078
Cash Payments Included in Measurement of Lease Liabilities	The table below details the cash payments included in the measurement of lease liabilities during the period presented ($ in thousands): Year Ended December 31, 2019 Finance leases Operating cash flows included in operating activities $ 307 Financing cash flows included in payments under finance lease obligations 1,964 Operating leases Operating cash flows (fixed payments) included in other operating activities, net 5,092 Operating cash flows (liability reduction) included in other operating activities, net 5,404
Balance Sheet Information and Weighted-Average Lease Terms and Discount Rates Related to Leases	The table below details balance sheet information, as well as weighted-average lease terms and discount rates, related to leases at December 31, 2019 ($ in thousands): December 31, 2019 Finance lease right-of-use assets, net of accumulated depreciation $ 9,326 Finance lease liabilities 9,520 Operating lease right-of-use assets 31,182 Operating lease liabilities 32,354 Weighted-average lease term Finance leases 8.62 years Operating leases 9.05 years Weighted-average discount rate Finance leases 3.01 % Operating leases 3.51 %
Future Minimum Rental Commitments Under Finance and Operating Leases	At December 31, 2019, future minimum rental commitments under finance and operating leases were as follows ($ in thousands): Finance Leases Operating Leases 2020 $ 1,970 $ 4,916 2021 1,615 4,576 2022 1,556 4,101 2023 871 4,064 2024 572 3,968 Thereafter 4,451 16,349 Total minimum lease payments 11,035 37,974 Less imputed interest (1,515 ) (5,620 ) Lease liabilities $ 9,520 $ 32,354

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Deposits Summary	At December 31, 2019 and 2018, deposits consisted of the following ($ in thousands): December 2019 2018 Noninterest-bearing demand $ 2,891,215 $ 2,937,594 Interest-bearing demand 3,125,914 2,633,259 Savings 3,590,509 3,905,659 Time 1,637,919 1,887,899 Total $ 11,245,557 $ 11,364,411
Interest Expense on Deposits by Type	Interest expense on deposits by type consisted of the following for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Interest-bearing demand $ 35,428 $ 18,479 $ 6,820 Savings 19,462 17,980 6,047 Time 24,281 17,477 9,850 Total $ 79,171 $ 53,936 $ 22,717
Maturities of Interest-Bearing Deposits	The maturities of interest-bearing deposits at December 31, 2019, are as follows ($ in thousands): 2020 $ 1,359,100 2021 190,554 2022 50,364 2023 20,995 2024 14,316 Thereafter 2,590 Total time deposits 1,637,919 Interest-bearing deposits with no stated maturity 6,716,423 Total interest-bearing deposits $ 8,354,342

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Securities Sold Under Repurchase Agreements	The following table presents the securities sold under repurchase agreements by collateral pledged at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 2018 Mortgage-backed securities Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA $ 24,282 $ 6,721 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 29,290 38,788 Total securities sold under repurchase agreements $ 53,572 $ 45,509
Summary of Other Borrowings	At December 31, 2019 and 2018, other borrowings consisted of the following ($ in thousands): December 2019 2018 FHLB advances $ 811 $ 879 Serviced GNMA loans eligible for repurchase 57,062 61,564 Finance lease liabilities 9,520 — Other 18,003 17,442 Total other borrowings $ 85,396 $ 79,885

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2019
Revenue From Contract With Customer [Abstract]
Summary of Noninterest Income Disaggregated by Reportable Operating Segment and Revenue Stream	The following table presents noninterest income disaggregated by reportable operating segment and revenue stream for the periods presented ($ in thousands): Year Ended December 31, 2019 Year Ended December 31, 2018 (1) Year Ended December 31, 2017 (1)(2) Topic 606 Not Topic 606 (3) Total Topic 606 Not Topic 606 (3) Total Topic 606 Not Topic 606 (3) Total General Banking Segment Service charges on deposit accounts $ 42,509 $ — $ 42,509 $ 43,614 $ — $ 43,614 $ 43,928 $ — $ 43,928 Bank card and other fees 27,972 3,706 31,678 26,904 1,897 28,801 27,958 250 28,208 Mortgage banking, net — 29,822 29,822 — 34,674 34,674 — 29,902 29,902 Wealth management 379 — 379 296 — 296 210 — 210 Other, net 9,527 (160 ) 9,367 6,762 (217 ) 6,545 6,547 7,234 13,781 Security gains (losses), net — — — — — — — 15 15 Total noninterest income $ 80,387 $ 33,368 $ 113,755 $ 77,576 $ 36,354 $ 113,930 $ 78,643 $ 37,401 $ 116,044 Wealth Management Segment Service charges on deposit accounts $ 94 $ — $ 94 $ 88 $ — $ 88 $ 75 $ — $ 75 Bank card and other fees 58 — 58 104 — 104 78 — 78 Wealth management 30,300 — 30,300 30,042 — 30,042 30,130 — 30,130 Other, net 306 103 409 69 117 186 20 118 138 Total noninterest income $ 30,758 $ 103 $ 30,861 $ 30,303 $ 117 $ 30,420 $ 30,303 $ 118 $ 30,421 Insurance Segment Insurance commissions $ 42,396 $ — $ 42,396 $ 40,481 $ — $ 40,481 $ 38,168 $ — $ 38,168 Other, net 33 — 33 5 — 5 30 — 30 Total noninterest income $ 42,429 $ — $ 42,429 $ 40,486 $ — $ 40,486 $ 38,198 $ — $ 38,198 Consolidated Service charges on deposit accounts $ 42,603 $ — $ 42,603 $ 43,702 $ — $ 43,702 $ 44,003 $ — $ 44,003 Bank card and other fees 28,030 3,706 31,736 27,008 1,897 28,905 28,036 250 28,286 Mortgage banking, net — 29,822 29,822 — 34,674 34,674 — 29,902 29,902 Insurance commissions 42,396 — 42,396 40,481 — 40,481 38,168 — 38,168 Wealth management 30,679 — 30,679 30,338 — 30,338 30,340 — 30,340 Other, net 9,866 (57 ) 9,809 6,836 (100 ) 6,736 6,597 7,352 13,949 Security gains (losses), net — — — — — — — 15 15 Total noninterest income $ 153,574 $ 33,471 $ 187,045 $ 148,365 $ 36,471 $ 184,836 $ 147,144 $ 37,519 $ 184,663 (1) During the first quarter of 2019, Trustmark revised the composition of its operating segments by moving the Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes. The prior period amounts presented include reclassifications to conform to the current period presentation. (2) Trustmark elected the modified retrospective approach of adoption; therefore, prior period balances are presented under legacy GAAP and may not be comparable to current year presentation. (3) Noninterest income not in scope for FASB ASC Topic 606 includes customer derivatives revenue and miscellaneous credit card income within bank card and other fees; mortgage banking, net; amortization of tax credits, accretion of the FDIC indemnification asset, cash surrender value on various life insurance policies, earnings on Trustmark’s non-qualified deferred compensation plans, other partnership investments and rental income within other, net; and securities gains (losses), net.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Tax Provision	The income tax provision included in the consolidated statements of income was as follows for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Current Federal $ 20,068 $ 4,532 $ 16,959 State 7,145 5,997 5,687 Deferred Federal (3,104 ) 9,392 7,280 State (776 ) 2,348 1,820 Income tax provision excluding deferred tax asset revaluation and reversal of valuation allowance 23,333 22,269 31,746 Deferred tax expense (benefit) - re-measurement of deferred tax assets — — 25,619 Deferred tax expense (benefit) - reversal of valuation allowance — — (8,650 ) Income tax provision $ 23,333 $ 22,269 $ 48,715
Income Tax Reconciliation	For the periods presented, the income tax provision differs from the amount computed by applying the statutory federal income tax rate in effect for each respective period to income before income taxes as a result of the following ($ in thousands): Years Ended December 31, 2019 2018 2017 Income tax computed at statutory tax rate $ 36,497 $ 36,089 $ 54,021 Tax exempt interest (4,951 ) (4,533 ) (7,611 ) Nondeductible interest expense 564 416 407 State income taxes, net 5,645 4,738 3,697 Income tax credits, net (13,473 ) (15,404 ) (15,793 ) Death benefit gains (123 ) (268 ) (3,268 ) Reversal of valuation allowance — — (8,650 ) Re-measurement of deferred tax assets — — 25,619 Other (826 ) 1,231 293 Income tax provision $ 23,333 $ 22,269 $ 48,715
Deferred Tax Assets and Liabilities	Temporary differences between the financial statement carrying amounts and the tax basis of assets and liabilities gave rise to the following net deferred tax assets at December 31, 2019 and 2018, which are included in other assets on the accompanying consolidated balance sheets ($ in thousands): December 31, 2019 2018 Deferred tax assets: Loan purchase accounting $ 845 $ 1,564 Other real estate 5,845 7,284 Allowance for loan losses 21,774 20,638 Deferred compensation 16,498 15,607 Financing and operating lease liabilities 10,469 — Realized built-in losses 11,431 12,182 Securities 3,028 3,929 Pension and other postretirement benefit plans 5,194 4,108 Interest on nonaccrual loans 942 806 Unrealized losses on securities available for sale — 10,679 Stock-based compensation 2,527 2,192 Federal carryovers — 1,606 Other 8,790 9,179 Gross deferred tax asset 87,343 89,774 Deferred tax liabilities: Goodwill and other identifiable intangibles 15,336 16,229 Premises and equipment 11,913 12,109 Financing and operating lease right-of-use assets 10,127 — Mortgage servicing rights 11,002 14,415 Securities 2,115 1,519 Other 5,192 5,600 Gross deferred tax liability 55,685 49,872 Net deferred tax asset $ 31,658 $ 39,902
Changes in Unrecognized Tax Benefits	The following table provides a summary of the changes during the 2019 calendar year in the amount of unrecognized tax benefits that are included in other liabilities in the consolidated balance sheet ($ in thousands): Balance at January 1, 2019 $ 1,249 Change due to tax positions taken during the current year 279 Change due to tax positions taken during a prior year 134 Change due to the lapse of applicable statute of limitations during the current year (138 ) Change due to settlements with taxing authorities during the current year — Balance at December 31, 2019 $ 1,524 Accrued interest, net of federal benefit, at December 31, 2019 $ 271 Unrecognized tax benefits that would impact the effective tax rate, if recognized, at December 31, 2019 $ 1,218

Defined Benefit and Other Pos_2

Defined Benefit and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2019
Trustmark Capital Accumulation Plan [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan Benefit Obligation, Plan Assets and Funded Status of the Plan	The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for the Continuing Plan and the Plan for the periods presented ($ in thousands): December 31, 2019 2018 Change in benefit obligation: Benefit obligation, beginning of year $ 9,179 $ 10,102 Service cost 211 277 Interest cost 361 332 Actuarial (gain) loss 875 (827 ) Benefits paid (1,566 ) (705 ) Benefit obligation, end of year $ 9,060 $ 9,179 Change in plan assets: Fair value of plan assets, beginning of year $ 3,954 $ 4,596 Actual return on plan assets 668 (314 ) Employer contributions 387 377 Benefit payments (1,566 ) (705 ) Fair value of plan assets, end of year $ 3,443 $ 3,954 Funded status at end of year - net liability $ (5,617 ) $ (5,225 ) Amounts recognized in accumulated other comprehensive loss: Net loss - amount recognized $ 1,893 $ 2,170
Net Periodic Benefit Cost	Years Ended December 31, 2019 2018 2017 Net periodic benefit cost: Service cost $ 211 $ 277 $ 253 Interest cost 361 332 1,461 Expected return on plan assets (202 ) (227 ) (317 ) Recognized net loss due to defined benefit plan termination — — 17,662 Recognized net loss due to lump sum settlements 312 161 — Recognized net actuarial loss 373 571 1,414 Net periodic benefit cost $ 1,055 $ 1,114 $ 20,473 Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes: Net loss - Total recognized in other comprehensive income (loss) $ (277 ) $ (1,017 ) $ (18,168 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ 778 $ 97 $ 2,305 Weighted-average assumptions as of end of year: Discount rate for benefit obligation 2.84 % 3.97 % 3.32 % Discount rate for net periodic benefit cost 3.97 % 3.32 % 3.71 % Expected long-term return on plan assets 5.00 % 5.00 % 5.00 %
Weighted-Average Asset Allocation	The weighted-average asset allocations by asset category are presented below for the Continuing Plan at December 31, 2019 and 2018. December 31, 2019 2018 Money market fund 2.0 % 8.0 % Exchange traded funds: Equity securities 46.0 % 52.0 % Fixed income 41.0 % 29.0 % International 11.0 % 11.0 % Total 100.0 % 100.0 %
Plan Assets Measured at Fair Value	The following table sets forth by level, within the fair value hierarchy, the Continuing Plan’s assets measured at fair value at December 31, 2019 and 2018 ($ in thousands): December 31, 2019 Total Level 1 Level 2 Level 3 Money market fund $ 51 $ 51 $ — $ — Exchange traded funds: Equity securities 1,592 1,592 — — Fixed income 1,417 1,417 — — International 383 383 — — Total assets at fair value $ 3,443 $ 3,443 $ — $ — December 31, 2018 Total Level 1 Level 2 Level 3 Money market fund $ 304 $ 304 $ — $ — Exchange traded funds: Equity securities 2,044 2,044 — — Fixed income 1,162 1,162 — — International 444 444 — — Total assets at fair value $ 3,954 $ 3,954 $ — $ —
Estimated Future Benefit Payments and Other Disclosures	The following table presents the expected benefit payments, which reflect expected future service, for the Continuing Plan ($ in thousands): Year Amount 2020 $ 1,147 2021 1,056 2022 873 2023 1,220 2024 997 2025 - 2029 2,443
Supplemental Retirement Plan [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan Benefit Obligation, Plan Assets and Funded Status of the Plan	The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for Trustmark’s nonqualified supplemental retirement plans for the periods presented ($ in thousands): December 31, 2019 2018 Change in benefit obligation: Benefit obligation, beginning of year $ 53,257 $ 57,930 Service cost 109 116 Interest cost 2,044 1,865 Actuarial (gain) loss 5,498 (3,228 ) Benefits paid (3,426 ) (3,426 ) Benefit obligation, end of year $ 57,482 $ 53,257 Change in plan assets: Fair value of plan assets, beginning of year $ — $ — Employer contributions 3,426 3,426 Benefit payments (3,426 ) (3,426 ) Fair value of plan assets, end of year $ — $ — Funded status at end of year - net liability $ (57,482 ) $ (53,257 ) Amounts recognized in accumulated other comprehensive loss: Net loss $ 18,275 $ 13,403 Prior service cost 609 859 Amounts recognized $ 18,884 $ 14,262
Net Periodic Benefit Cost	Years Ended December 31, 2019 2018 2017 Net periodic benefit cost: Service cost $ 109 $ 116 $ 141 Interest cost 2,044 1,865 2,103 Amortization of prior service cost 250 250 250 Recognized net actuarial loss 627 884 866 Net periodic benefit cost $ 3,030 $ 3,115 $ 3,360 Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes: Net (gain) loss $ 4,872 $ (4,111 ) $ (224 ) Amortization of prior service cost (250 ) (250 ) (250 ) Total recognized in other comprehensive income (loss) $ 4,622 $ (4,361 ) $ (474 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ 7,652 $ (1,246 ) $ 2,886 Weighted-average assumptions as of end of year: Discount rate for benefit obligation 2.84 % 3.97 % 3.32 % Discount rate for net periodic benefit cost 3.97 % 3.32 % 3.71 %
Estimated Future Benefit Payments and Other Disclosures	The following table presents the expected benefits payments for Trustmark’s supplemental retirement plans ($ in thousands): Year Amount 2020 $ 3,963 2021 4,051 2022 4,284 2023 4,124 2024 4,144 2025 - 2029 17,840

Stock and Incentive Compensat_2

Stock and Incentive Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Plan Activity	The following table summarizes Trustmark’s performance award activity for the periods presented: Years Ended December 31, 2019 2018 2017 Weighted- Weighted- Weighted- Average Average Average Grant-Date Grant-Date Grant-Date Shares Fair Value Shares Fair Value Shares Fair Value Nonvested shares, beginning of year 177,695 $ 27.10 213,516 $ 25.37 237,136 $ 26.27 Granted 50,862 33.44 51,174 31.88 58,406 33.31 Released from restriction (61,347 ) 20.18 (55,351 ) 25.32 (67,279 ) 34.78 Forfeited (17,296 ) 20.18 (31,644 ) 26.26 (14,747 ) 28.42 Nonvested shares, end of year 149,914 $ 32.88 177,695 $ 27.10 213,516 $ 25.37 The following table summarizes Trustmark’s time-vested award activity for the periods presented: Years Ended December 31, 2019 2018 2017 Weighted- Weighted- Weighted- Average Average Average Grant-Date Grant-Date Grant-Date Shares Fair Value Shares Fair Value Shares Fair Value Nonvested shares, beginning of year 321,870 $ 28.48 320,357 $ 25.40 322,056 $ 22.65 Granted 113,673 33.42 118,325 31.96 105,524 33.79 Released from restriction (124,598 ) 21.64 (107,180 ) 23.02 (101,289 ) 25.35 Forfeited (10,939 ) 32.73 (9,632 ) 29.30 (5,934 ) 26.52 Nonvested shares, end of year 300,006 $ 33.04 321,870 $ 28.48 320,357 $ 25.40
Compensation Expense for Awards Under Stock Plan	The following table presents information regarding compensation expense for awards under the Stock Plan for the periods presented ($ in thousands): At December 31, 2019 Recognized Compensation Expense Unrecognized Weighted Average for Years Ended December 31, Compensation Life of 2019 2018 2017 Expense Compensation Expense Performance awards $ 1,524 $ 861 $ 1,387 $ 1,914 1.59 Time-vested awards 3,263 3,009 2,922 3,726 1.73 Total $ 4,787 $ 3,870 $ 4,309 $ 5,640

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Stockholders Equity Note [Abstract]
Table of Actual Regulatory Capital Amounts and Ratios	The following table provides Trustmark’s and TNB’s actual regulatory capital amounts and ratios under regulatory capital standards in effect at December 31, 2019 and 2018 ($ in thousands): Actual Regulatory Capital Minimum To Be Well Amount Ratio Requirement Capitalized At December 31, 2019: Common Equity Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,312,668 11.93 % 7.000 % n/a Trustmark National Bank 1,352,893 12.30 % 7.000 % 6.50 % Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,372,668 12.48 % 8.500 % n/a Trustmark National Bank 1,352,893 12.30 % 8.500 % 8.00 % Total Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,457,760 13.25 % 10.500 % n/a Trustmark National Bank 1,437,985 13.07 % 10.500 % 10.00 % Tier 1 Leverage (to Average Assets) Trustmark Corporation $ 1,372,668 10.48 % 4.00 % n/a Trustmark National Bank 1,352,893 10.35 % 4.00 % 5.00 % At December 31, 2018: Common Equity Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,271,538 11.77 % 6.375 % n/a Trustmark National Bank 1,311,548 12.14 % 6.375 % 6.50 % Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,331,538 12.33 % 7.875 % n/a Trustmark National Bank 1,311,548 12.14 % 7.875 % 8.00 % Total Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,412,059 13.07 % 9.875 % n/a Trustmark National Bank 1,392,069 12.89 % 9.875 % 10.00 % Tier 1 Leverage (to Average Assets) Trustmark Corporation $ 1,331,538 10.26 % 4.00 % n/a Trustmark National Bank 1,311,548 10.13 % 4.00 % 5.00 %
Net Change in Components of Accumulated Other Comprehensive Income (Loss) and the Related Tax Effects	Before Tax Tax Net of Tax Amount Benefit Amount Year Ended December 31, 2019 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ 44,136 $ (11,033 ) $ 33,103 Change in net unrealized holding loss on securities transferred to held to maturity 3,605 (901 ) 2,704 Total securities available for sale and transferred securities 47,741 (11,934 ) 35,807 Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans (5,703 ) 1,425 (4,278 ) Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (63 ) 187 Recognized net loss due to lump sum settlements 312 (77 ) 235 Change in net actuarial loss 796 (199 ) 597 Total pension and other postretirement benefit plans (4,345 ) 1,086 (3,259 ) Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives (145 ) 36 (109 ) Reclassification adjustment for (gain) loss realized in net income (479 ) 119 (360 ) Total cash flow hedge derivatives (624 ) 155 (469 ) Total other comprehensive income (loss) $ 42,772 $ (10,693 ) $ 32,079 Year Ended December 31, 2018 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ (19,221 ) $ 4,805 $ (14,416 ) Change in net unrealized holding loss on securities transferred to held to maturity 3,761 (940 ) 2,821 Total securities available for sale and transferred securities (15,460 ) 3,865 (11,595 ) Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans 3,742 (936 ) 2,806 Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (63 ) 187 Recognized net loss due to lump sum settlements 161 (39 ) 122 Change in net actuarial loss 1,225 (306 ) 919 Total pension and other postretirement benefit plans 5,378 (1,344 ) 4,034 Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives 497 (124 ) 373 Reclassification adjustment for (gain) loss realized in net income (322 ) 80 (242 ) Total cash flow hedge derivatives 175 (44 ) 131 Total other comprehensive income (loss) $ (9,907 ) $ 2,477 $ (7,430 ) Year Ended December 31, 2017 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ (13,994 ) $ 5,353 $ (8,641 ) Reclassification adjustment for net (gains) losses realized in net income (15 ) 6 (9 ) Change in net unrealized holding loss on securities transferred to held to maturity 4,721 (1,806 ) 2,915 Total securities available for sale and transferred securities (9,288 ) 3,553 (5,735 ) Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans (1,231 ) 471 (760 ) Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (96 ) 154 Change in net actuarial loss 1,962 (751 ) 1,211 Recognized net loss due to defined benefit plan termination 17,662 (6,755 ) 10,907 Total pension and other postretirement benefit plans 18,643 (7,131 ) 11,512 Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives 198 (76 ) 122 Reclassification adjustment for (gain) loss realized in net income 282 (108 ) 174 Total cash flow hedge derivatives 480 (184 ) 296 Total other comprehensive income (loss) $ 9,835 $ (3,762 ) $ 6,073
Components of Reclassifications Out of Accumulated Other Comprehensive Income (Loss)	The following table presents the changes in the balances of each component of accumulated other comprehensive loss for the periods presented ($ in thousands). All amounts are presented net of tax. Securities Available and Securities Defined Benefit Pension Items Cash Flow Hedge Derivative Total Balance, January 1, 2017 $ (20,800 ) $ (24,980 ) $ (18 ) $ (45,798 ) Other comprehensive income (loss) before reclassification (5,726 ) (760 ) 122 (6,364 ) Amounts reclassified from accumulated other comprehensive loss (9 ) 12,272 174 12,437 Net other comprehensive income (loss) (5,735 ) 11,512 296 6,073 Balance, December 31, 2017 (26,535 ) (13,468 ) 278 (39,725 ) Other comprehensive income (loss) before reclassification (11,595 ) 2,806 373 (8,416 ) Amounts reclassified from accumulated other comprehensive loss — 1,228 (242 ) 986 Net other comprehensive income (loss) (11,595 ) 4,034 131 (7,430 ) Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act (5,694 ) (2,890 ) 60 (8,524 ) Balance, December 31, 2018 (43,824 ) (12,324 ) 469 (55,679 ) Other comprehensive income (loss) before reclassification 35,807 (4,278 ) (109 ) 31,420 Amounts reclassified from accumulated other comprehensive loss — 1,019 (360 ) 659 Net other comprehensive income (loss) 35,807 (3,259 ) (469 ) 32,079 Balance, December 31, 2019 $ (8,017 ) $ (15,583 ) $ — $ (23,600 )

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured at Fair Value Recurring Basis	The following tables summarize financial assets and financial liabilities measured at fair value on a recurring basis as of December 31, 2019 and 2018, segregated by the level of valuation inputs within the fair value hierarchy utilized to measure fair value ($ in thousands). There were no transfers between fair value levels for the years ended December 31, 2019 and 2018. December 31, 2019 Total Level 1 Level 2 Level 3 U.S. Government agency obligations $ 22,327 $ — $ 22,327 $ — Obligations of states and political subdivisions 25,465 — 25,465 — Mortgage-backed securities 1,554,612 — 1,554,612 — Securities available for sale 1,602,404 — 1,602,404 — Loans held for sale 226,347 — 226,347 — Mortgage servicing rights 79,394 — — 79,394 Other assets - derivatives 17,956 244 16,273 1,439 Other liabilities - derivatives 6,063 4,414 1,649 — December 31, 2018 Total Level 1 Level 2 Level 3 U.S. Government agency obligations $ 30,335 $ — $ 30,335 $ — Obligations of states and political subdivisions 50,676 — 50,676 — Mortgage-backed securities 1,730,802 — 1,730,802 — Securities available for sale 1,811,813 — 1,811,813 — Loans held for sale 153,799 — 153,799 — Mortgage servicing rights 95,596 — — 95,596 Other assets - derivatives 12,347 5,006 6,154 1,187 Other liabilities - derivatives 4,213 66 4,147 —
Changes in Level 3 Assets Measured at Fair Value on a Recurring Basis	The changes in Level 3 assets measured at fair value on a recurring basis for the years ended December 31, 2019 and 2018 are summarized as follows ($ in thousands): MSR Other Assets - Derivatives Balance, January 1, 2019 $ 95,596 $ 1,187 Total net (loss) gain included in Mortgage banking, net (1) (32,913 ) 6,775 Additions 16,711 — Sales — (6,523 ) Balance, December 31, 2019 $ 79,394 $ 1,439 The amount of total gains (losses) for the period included in earnings that are attributable to the change in unrealized gains or losses still held at December 31, 2019 $ (21,078 ) $ 1,284 Balance, January 1, 2018 $ 84,269 $ 900 Total net (loss) gain included in Mortgage banking, net (1) (4,432 ) 4,390 Additions 15,759 — Sales — (4,103 ) Balance, December 31, 2018 $ 95,596 $ 1,187 The amount of total gains (losses) for the period included in earnings that are attributable to the change in unrealized gains or losses still held at December 31, 2018 $ 7,342 $ 636 (1) Total net (loss) gain included in Mortgage banking, net relating to the MSR includes changes in fair value due to market changes and due to run-off.
Carrying Amounts and Estimated Fair Values of Financial Instruments	The carrying amounts and estimated fair values of financial instruments at December 31, 2019 and 2018 were as follows ($ in thousands): December 31, 2019 December 31, 2018 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Financial Assets: Level 2 Inputs: Cash and short-term investments $ 358,916 $ 358,916 $ 350,391 $ 350,391 Securities held to maturity 738,099 746,202 909,643 889,733 Level 3 Inputs: Net LHFI 9,251,351 9,235,674 8,756,578 8,757,817 Net acquired loans 71,786 71,786 105,701 105,701 Financial Liabilities: Level 2 Inputs: Deposits 11,245,557 11,250,071 11,364,411 11,365,203 Federal funds purchased and securities sold under repurchase agreements 256,020 256,020 50,471 50,471 Other borrowings 85,396 85,374 79,885 79,827 Junior subordinated debt securities 61,856 50,722 61,856 53,196
Fair Value and the Contractual Principal Outstanding of the LHFS	The following table provides information about the fair value and the contractual principal outstanding of the LHFS accounted for under the fair value option as of December 31, 2019 and 2018 ($ in thousands): December 31, 2019 2018 Fair value of LHFS $ 169,285 $ 92,235 LHFS contractual principal outstanding 164,420 89,056 Fair value less unpaid principal $ 4,865 $ 3,179

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments	The following tables disclose the fair value of derivative instruments in Trustmark’s consolidated balance sheets as of December 31, 2019 and 2018 as well as the effect of these derivative instruments on Trustmark’s results of operations for the periods presented ($ in thousands): December 31, 2019 2018 Derivatives in hedging relationships Interest rate contracts: Interest rate swaps included in other assets $ — $ 625 Derivatives not designated as hedging instruments Interest rate contracts: Futures contracts included in other assets $ — $ 4,445 Exchange traded purchased options included in other assets 244 561 OTC written options (rate locks) included in other assets 1,439 1,187 Interest rate swaps included in other assets 16,209 5,487 Credit risk participation agreements included in other assets 64 42 Futures contracts included in other liabilities 2,654 — Forward contracts included in other liabilities 486 1,773 Exchange traded written options included in other liabilities 1,760 66 Interest rate swaps included in other liabilities 1,122 2,369 Credit risk participation agreements included in other liabilities 41 5
Effects of Derivative Instruments on Statements of Operations	Years Ended December 31, 2019 2018 2017 Derivatives in hedging relationships Amount of gain (loss) reclassified from accumulated other comprehensive loss and recognized in other interest expense $ 479 $ 322 $ (282 ) Derivatives not designated as hedging instruments Amount of gain (loss) recognized in mortgage banking, net $ 11,096 $ (6,191 ) $ (1,873 ) Amount of gain (loss) recognized in bank card and other fees (776 ) (357 ) (31 )
Schedule of Amount Included in Other Comprehensive Income for Derivative Instruments Designated as Hedges of Cash Flows	The following table discloses the amount included in other comprehensive income (loss), net of tax, for derivative instruments designated as cash flow hedges for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 Derivatives in cash flow hedging relationship Amount of gain (loss) recognized in other comprehensive income (loss), net of tax $ (109 ) $ 373 $ 122
Information about Financial Instruments that are Eligible for Offset in the Consolidated Balance Sheets	Information about financial instruments that are eligible for offset in the consolidated balance sheets as of December 31, 2019 and 2018 is presented in the following tables ($ in thousands): Offsetting of Derivative Assets As of December 31, 2019 Gross Statement of Financial Position Gross Amounts of Recognized Assets Gross Amounts Offset in the Statement of Financial Position Net Amounts of Assets presented in the Statement of Financial Position Financial Instruments Cash Collateral Received Net Amount Derivatives $ 16,209 $ — $ 16,209 $ — $ — $ 16,209 Offsetting of Derivative Liabilities As of December 31, 2019 Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Statement of Financial Position Net Amounts of Liabilities presented in the Statement of Financial Position Financial Instruments Cash Collateral Posted Net Amount Derivatives $ 1,122 $ — $ 1,122 $ — $ (1,390 ) $ (268 ) Offsetting of Derivative Assets As of December 31, 2018 Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Assets Gross Amounts Offset in the Statement of Financial Position Net Amounts of Assets presented in Financial Position Financial Instruments Cash Collateral Received Net Amount Derivatives $ 6,112 $ — $ 6,112 $ (339 ) $ (620 ) $ 5,153 Offsetting of Derivative Liabilities As of December 31, 2018 Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Statement of Financial Position Net Amounts of Liabilities presented in the Statement of Financial Position Financial Instruments Cash Collateral Posted Net Amount Derivatives $ 2,369 $ — $ 2,369 $ (339 ) $ — $ 2,030

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Schedule of Segment Information	The following table discloses financial information by reportable segment for the periods presented ($ in thousands): Years Ended December 31, 2019 2018 2017 General Banking Net interest income $ 422,661 $ 415,561 $ 402,507 Provision for loan losses, net 10,838 17,001 7,485 Noninterest income 113,755 113,930 116,044 Noninterest expense 370,493 355,389 370,793 Income before income taxes 155,085 157,101 140,273 Income taxes 18,721 18,560 43,427 General banking net income $ 136,364 $ 138,541 $ 96,846 Selected Financial Information Total assets $ 13,333,518 $ 13,111,362 $ 13,627,012 Depreciation and amortization $ 38,637 $ 38,182 $ 37,704 Wealth Management Net interest income $ 3,686 $ 3,633 $ 4,809 Provision for loan losses, net 1 (13 ) 214 Noninterest income 30,861 30,420 30,421 Noninterest expense 26,365 29,170 29,989 Income before income taxes 8,181 4,896 5,027 Income taxes 2,040 1,225 1,923 Wealth Management net income $ 6,141 $ 3,671 $ 3,104 Selected Financial Information Total assets $ 90,113 $ 106,179 $ 102,773 Depreciation and amortization $ 267 $ 186 $ 137 Insurance Net interest income $ 242 $ 226 $ 234 Noninterest income 42,429 40,486 38,198 Noninterest expense 32,144 30,856 29,387 Income before income taxes 10,527 9,856 9,045 Income taxes 2,572 2,484 3,365 Insurance net income $ 7,955 $ 7,372 $ 5,680 Selected Financial Information Total assets $ 74,246 $ 68,919 $ 68,168 Depreciation and amortization $ 516 $ 572 $ 630 Consolidated Net interest income $ 426,589 $ 419,420 $ 407,550 Provision for loan losses, net 10,839 16,988 7,699 Noninterest income 187,045 184,836 184,663 Noninterest expense 429,002 415,415 430,169 Income before income taxes 173,793 171,853 154,345 Income taxes 23,333 22,269 48,715 Consolidated net income $ 150,460 $ 149,584 $ 105,630 Selected Financial Information Total assets $ 13,497,877 $ 13,286,460 $ 13,797,953 Depreciation and amortization $ 39,420 $ 38,940 $ 38,471

Parent Company Only Financial_2

Parent Company Only Financial Information (Tables)	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Parent Only Financial Statements	Condensed Balance Sheets December 31, 2019 2018 Assets: Investment in banks $ 1,707,644 $ 1,637,338 Other assets 15,778 16,975 Total Assets $ 1,723,422 $ 1,654,313 Liabilities and Shareholders' Equity: Accrued expense $ 864 $ 1,004 Junior subordinated debt securities 61,856 61,856 Shareholders' equity 1,660,702 1,591,453 Total Liabilities and Shareholders' Equity $ 1,723,422 $ 1,654,313 Condensed Statements of Income Years Ended December 31, 2019 2018 2017 Revenue: Dividends received from banks $ 120,297 $ 128,592 $ 65,663 Earnings of subsidiaries over distributions 32,971 23,791 42,211 Other income 90 86 71 Total Revenue 153,358 152,469 107,945 Expense: Other expense 2,898 2,885 2,315 Total Expense 2,898 2,885 2,315 Net Income $ 150,460 $ 149,584 $ 105,630 Condensed Statements of Cash Flows Years Ended December 31, 2019 2018 2017 Operating Activities: Net income $ 150,460 $ 149,584 $ 105,630 Adjustments to reconcile net income to net cash provided by operating activities: Net change in investment in subsidiaries (32,971 ) (23,791 ) (42,211 ) Other (1,800 ) (1,395 ) (1,697 ) Net cash from operating activities 115,689 124,398 61,722 Investing Activities: Payment for investments in subsidiaries — — (30,755 ) Repayment for investments in subsidiaries — — 32,000 Net cash from investing activities — — 1,245 Financing Activities: Common stock dividends (59,804 ) (62,425 ) (62,795 ) Repurchase and retirement of common stock (56,615 ) (62,421 ) — Net cash from financing activities (116,419 ) (124,846 ) (62,795 ) Net change in cash and cash equivalents (730 ) (448 ) 172 Cash and cash equivalents at beginning of year 16,437 16,885 16,713 Cash and cash equivalents at end of year $ 15,707 $ 16,437 $ 16,885

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019USD ($)OfficeFactorRegionFeeRevenueCategoryContract	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Mar. 31, 2019USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of offices | Office	193
Percentage of outstanding principal to be repurchased under GNMA optional repurchase program	100.00%
Number of days to pass to be classified as past due LHFI	30 days
Balance of commercial nonaccrual loans identified for impairment analysis, minimum	$ 500,000
Components in allowance for loan losses methodology | Factor	3
Key market regions | Region	5
Finite-lived intangible assets, average useful life	20 years
Securities with limited marketability	$ 31,900,000	$ 32,200,000
Number of types of interchange fees | Fee	2
Other real estate sales, net (losses) gains	$ (291,000)	700,000	$ 2,087,000
Number of trust management revenue categories | RevenueCategory	5
Time period between service obligation completed and payment received from trust customer	30 days
Operating lease right-of-use assets	$ 31,182,000			$ 33,900,000
Operating lease liabilities	32,354,000			34,900,000
Finance lease right-of-use assets, net of accumulated depreciation	9,326,000	0		11,200,000
Finance lease liabilities	$ 9,520,000			$ 11,200,000
Percentage of right-of-use assets on total assets				0.30%
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Summary Of Significant Accounting Policies [Line Items]
Description of variable rate basis for derivative	three-month LIBOR
Period for which cash flow hedges will be used to hedge quarterly interest payments	5 years
Derivative inception date	Dec. 31, 2014
Derivative maturity date	Dec. 31, 2019
Accumulated net after-tax amount related to effective cash flow hedge	$ 0	$ 469,000
Fisher Brown Bottrell Insurance, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of general categories of insurance contracts | Contract	4
Credit Card Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due loans are to be charged-off	180 days
Commercial Credits [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due for loan to be classified as nonaccrual	90 days
Non-Business Purpose Credits [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due for loan to be classified as nonaccrual	120 days
Number of days past due loans are to be charged-off	120 days
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days mortgage LHFS are retained on balance sheet	30 days
Minimum [Member] | ASU 2016-13 [Member]
Summary Of Significant Accounting Policies [Line Items]
Expected increase in allowance for loan losses	$ 10,000,000
Minimum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Personal Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period	30 days
Minimum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Employee Benefits Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period	60 days
Minimum [Member] | Furniture and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days mortgage LHFS are retained on balance sheet	45 days
Maximum [Member] | ASU 2016-13 [Member]
Summary Of Significant Accounting Policies [Line Items]
Expected increase in allowance for loan losses	$ 35,000,000
Maximum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Personal Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period	60 days
Maximum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Employee Benefits Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period	90 days
Maximum [Member] | Buildings [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	39 years
Maximum [Member] | Furniture and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	10 years
Maximum [Member] | 1-4 Family Residential Real Estate [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due loans are to be charged-off	180 days

Significant Accounting Polici_5

Significant Accounting Policies - Additional Information (Details 1) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01	Dec. 31, 2019
Personal Insurance Contracts [Member] | Fisher Brown Bottrell Insurance, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenue recognition contract term	1 year
Employee Benefits Insurance Contracts [Member] | Fisher Brown Bottrell Insurance, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenue recognition contract term	1 year
Contingency Commission Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenue recognition contract term	1 year
Maximum [Member] | Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenue recognition contract term	1 year

Significant Accounting Polici_6

Significant Accounting Policies - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of cash flows specific transaction amounts [Abstract]
Income taxes paid	$ 24,809	$ 12,435	$ 7,371
Interest paid on deposits and borrowings	83,997	66,358	41,472
Noncash transfers from loans to other real estate	8,598	$ 12,115	8,760
Investment in tax credit partnership not funded	5,000
Financing right-of-use assets resulting from lease liabilities	9,326
Operating right-of-use assets resulting from lease liabilities	$ 31,182
Transfer of long-term FHLB advances to short-term			250,038
Assets acquired in business combination			196,265
Liabilities assumed in business combination			$ 184,949

Significant Accounting Polici_7

Significant Accounting Policies - Weighted-Average Shares Used to Calculate Basic and Diluted EPS (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share (EPS) [Abstract]
Basic shares	64,630	67,505	67,727
Dilutive shares	142	154	160
Diluted shares	64,772	67,659	67,887

Significant Accounting Polici_8

Significant Accounting Policies - Weighted-Average Antidilutive Stock Awards Excluded from Determining Diluted EPS (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Weighted-average antidilutive stock awards (in shares)	1	74

Business Combinations - Additio

Business Combinations - Additional Information (Details) $ / shares in Units, $ in Thousands	Apr. 07, 2017USD ($)Office	Jun. 30, 2017USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Nov. 14, 2016$ / shares
Business Acquisition [Line Items]
Goodwill			$ 379,627	$ 379,627	$ 379,627
Intangible asset estimated useful life			20 years
Reliance [Member]
Business Acquisition [Line Items]
Number of offices | Office	7
Business acquisition agreement date	Nov. 14, 2016
Business acquisition, share price | $ / shares						$ 22
Total consideration paid	$ 24,800
Goodwill	$ 13,471
Intangible asset estimated useful life	10 years
Reliance [Member] | Other Noninterest Expense [Member]
Business Acquisition [Line Items]
Merger transaction expense		$ 3,200
Reliance [Member] | Other Noninterest Expense [Member] | Change In Control Expense [Member]
Business Acquisition [Line Items]
Merger transaction expense		1,300
Reliance [Member] | Other Noninterest Expense [Member] | Professional Fees and Contract Termination and Other Expenses [Member]
Business Acquisition [Line Items]
Merger transaction expense		$ 1,900
Reliance [Member] | Reliance Common Stock [Member]
Business Acquisition [Line Items]
Business acquisition, payment for equity	$ 23,700
Reliance [Member] | Reliance Preferred Stock [Member]
Business Acquisition [Line Items]
Business acquisition, payment for equity	$ 1,100

Business Combinations - Summary

Business Combinations - Summary of Estimated Fair Values of Assets Purchased and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Apr. 07, 2017
Liabilities:
Goodwill	$ 379,627	$ 379,627	$ 379,627
Reliance [Member]
Assets:
Cash and due from banks				$ 5,013
Federal funds sold and securities purchased under reverse repurchase agreements				6,900
Securities				54,843
Acquired loans				117,447
Premises and equipment, net				3,700
Identifiable intangible assets				1,850
Other real estate				475
Other assets				6,037
Total Assets				196,265
Liabilities:
Deposits				166,158
Other borrowings				17,469
Other liabilities				1,322
Total Liabilities				184,949
Net identified assets acquired at fair value				11,316
Goodwill				13,471
Total consideration paid				$ 24,787

Cash and Due from Banks - Addit

Cash and Due from Banks - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash And Cash Equivalents [Abstract]
Average reserve balances with Federal Reserve Bank	$ 122.4	$ 112.4

Securities Available for Sale_3

Securities Available for Sale and Held to Maturity - Amortized Cost and Estimated Fair Value of Available for Sale and Held to Maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	$ 1,600,984	$ 1,854,529
Securities Available for Sale, Gross Unrealized Gains	7,580	841
Securities Available for Sale, Gross Unrealized (Losses)	(6,160)	(43,557)
Securities Available for Sale, Estimated Fair Value	1,602,404	1,811,813
Securities Held to Maturity, Amortized Cost	738,099	909,643
Securities Held to Maturity, Gross Unrealized Gains	9,274	909
Securities Held to Maturity, Gross Unrealized (Losses)	(1,171)	(20,819)
Securities Held to Maturity, Estimated Fair Value	746,202	889,733
U.S. Government Agency Obligations [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	22,965	31,235
Securities Available for Sale, Gross Unrealized Gains	69	109
Securities Available for Sale, Gross Unrealized (Losses)	(707)	(1,009)
Securities Available for Sale, Estimated Fair Value	22,327	30,335
Securities Held to Maturity, Amortized Cost	3,781	3,736
Securities Held to Maturity, Gross Unrealized Gains	220	78
Securities Held to Maturity, Gross Unrealized (Losses)	0	0
Securities Held to Maturity, Estimated Fair Value	4,001	3,814
Obligations of States and Political Subdivisions [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	24,952	50,503
Securities Available for Sale, Gross Unrealized Gains	513	200
Securities Available for Sale, Gross Unrealized (Losses)	0	(27)
Securities Available for Sale, Estimated Fair Value	25,465	50,676
Securities Held to Maturity, Amortized Cost	31,781	35,783
Securities Held to Maturity, Gross Unrealized Gains	434	255
Securities Held to Maturity, Gross Unrealized (Losses)	(53)	(139)
Securities Held to Maturity, Estimated Fair Value	32,162	35,899
Residential Mortgage Pass-Through Securities Guaranteed by GNMA [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	69,196	69,648
Securities Available for Sale, Gross Unrealized Gains	425	147
Securities Available for Sale, Gross Unrealized (Losses)	(369)	(2,301)
Securities Available for Sale, Estimated Fair Value	69,252	67,494
Securities Held to Maturity, Amortized Cost	10,820	12,090
Securities Held to Maturity, Gross Unrealized Gains	266	45
Securities Held to Maturity, Gross Unrealized (Losses)	(10)	(257)
Securities Held to Maturity, Estimated Fair Value	11,076	11,878
Residential Mortgage Pass-Through Securities Issued by FNMA and FHLMC [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	714,350	685,520
Securities Available for Sale, Gross Unrealized Gains	2,171	127
Securities Available for Sale, Gross Unrealized (Losses)	(3,165)	(18,963)
Securities Available for Sale, Estimated Fair Value	713,356	666,684
Securities Held to Maturity, Amortized Cost	96,631	115,133
Securities Held to Maturity, Gross Unrealized Gains	286	43
Securities Held to Maturity, Gross Unrealized (Losses)	(370)	(2,887)
Securities Held to Maturity, Estimated Fair Value	96,547	112,289
Other Residential Mortgage-Backed Securities Issued or Guaranteed by FNMA, FHLMC or GNMA [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	656,162	830,129
Securities Available for Sale, Gross Unrealized Gains	3,777	67
Securities Available for Sale, Gross Unrealized (Losses)	(1,713)	(18,595)
Securities Available for Sale, Estimated Fair Value	658,226	811,601
Securities Held to Maturity, Amortized Cost	485,324	578,827
Securities Held to Maturity, Gross Unrealized Gains	7,026	189
Securities Held to Maturity, Gross Unrealized (Losses)	(656)	(15,441)
Securities Held to Maturity, Estimated Fair Value	491,694	563,575
Commercial Mortgage-Backed Securities Issued or Guaranteed by FNMA, FHLMC or GNMA [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	113,359	187,494
Securities Available for Sale, Gross Unrealized Gains	625	191
Securities Available for Sale, Gross Unrealized (Losses)	(206)	(2,662)
Securities Available for Sale, Estimated Fair Value	113,778	185,023
Securities Held to Maturity, Amortized Cost	109,762	164,074
Securities Held to Maturity, Gross Unrealized Gains	1,042	299
Securities Held to Maturity, Gross Unrealized (Losses)	(82)	(2,095)
Securities Held to Maturity, Estimated Fair Value	$ 110,722	$ 162,278

Securities Available for Sale_4

Securities Available for Sale and Held to Maturity - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]
Reclassification of Securities available for sale to securities held to maturity				$ 1,099,000,000
Net unrealized holding loss on AFS Securities at date of transfer				46,600,000
Net unrealized holding losses on AFS Securities, net of tax at date of transfer				$ 28,800,000
Net unamortized, unrealized loss on transfer of securities	$ 12,100,000	$ 15,700,000
Net unamortized, unrealized loss on transfer of securities, net of tax	9,100,000	11,800,000
Other-than-temporary impairments	0	0	$ 0
Pledged to collateralize public deposits and securities sold under repurchase agreements and for other purposes as permitted by law	1,770,000,000	2,144,000,000
Pledged securities providing additional contingency funding	$ 0	$ 0

Securities Available for Sale_5

Securities Available for Sale and Held to Maturity - Securities with Gross Unrealized Losses, Segregated by Length of Impairment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	$ 352,661	$ 98,188
Estimated Fair Value, 12 Months or More	481,177	2,399,747
Estimated Fair Value, Total	833,838	2,497,935
Gross Unrealized (Losses), Less than 12 Months	(1,347)	(382)
Gross Unrealized (Losses), 12 Months or More	(5,984)	(63,994)
Gross Unrealized (Losses), Total	(7,331)	(64,376)
U.S. Government Agency Obligations [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	6,585	0
Estimated Fair Value, 12 Months or More	12,886	25,045
Estimated Fair Value, Total	19,471	25,045
Gross Unrealized (Losses), Less than 12 Months	(105)	0
Gross Unrealized (Losses), 12 Months or More	(602)	(1,009)
Gross Unrealized (Losses), Total	(707)	(1,009)
Obligations of States and Political Subdivisions [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	0	4,954
Estimated Fair Value, 12 Months or More	6,216	12,802
Estimated Fair Value, Total	6,216	17,756
Gross Unrealized (Losses), Less than 12 Months	0	(9)
Gross Unrealized (Losses), 12 Months or More	(53)	(157)
Gross Unrealized (Losses), Total	(53)	(166)
Residential Mortgage Pass-Through Securities Guaranteed by GNMA [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	23,544	9,163
Estimated Fair Value, 12 Months or More	18,529	61,141
Estimated Fair Value, Total	42,073	70,304
Gross Unrealized (Losses), Less than 12 Months	(107)	(54)
Gross Unrealized (Losses), 12 Months or More	(272)	(2,504)
Gross Unrealized (Losses), Total	(379)	(2,558)
Residential Mortgage Pass-Through Securities Issued by FNMA and FHLMC [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	112,879	31,931
Estimated Fair Value, 12 Months or More	278,120	731,749
Estimated Fair Value, Total	390,999	763,680
Gross Unrealized (Losses), Less than 12 Months	(230)	(172)
Gross Unrealized (Losses), 12 Months or More	(3,305)	(21,678)
Gross Unrealized (Losses), Total	(3,535)	(21,850)
Other Residential Mortgage-Backed Securities Issued or Guaranteed by FNMA, FHLMC or GNMA [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	158,341	46,643
Estimated Fair Value, 12 Months or More	151,271	1,296,221
Estimated Fair Value, Total	309,612	1,342,864
Gross Unrealized (Losses), Less than 12 Months	(738)	(110)
Gross Unrealized (Losses), 12 Months or More	(1,631)	(33,926)
Gross Unrealized (Losses), Total	(2,369)	(34,036)
Commercial Mortgage-Backed Securities Issued or Guaranteed by FNMA, FHLMC or GNMA [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	51,312	5,497
Estimated Fair Value, 12 Months or More	14,155	272,789
Estimated Fair Value, Total	65,467	278,286
Gross Unrealized (Losses), Less than 12 Months	(167)	(37)
Gross Unrealized (Losses), 12 Months or More	(121)	(4,720)
Gross Unrealized (Losses), Total	$ (288)	$ (4,757)

Securities Available for Sale_6

Securities Available for Sale and Held to Maturity - Gains and Losses as a Result of Calls and Disposition of Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gains (losses) on Investments [Abstract]
Proceeds from calls and sales of securities	$ 0	$ 0	$ 27,682
Gross realized gains	0	0	16
Gross realized losses	$ 0	$ 0	$ (1)

Securities Available for Sale_7

Securities Available for Sale and Held to Maturity - Contractual Maturities of Available for Sale and Held to Maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Securities Available for Sale, Amortized Cost [Abstract]
Due in one year or less	$ 22,480
Due after one year through five years	1,598
Due after five years through ten years	2,561
Due after ten years	21,278
Total amortized cost, before mortgage-backed securities	47,917
Mortgage-backed securities	1,553,067
Securities Available for Sale, Amortized Cost	1,600,984	$ 1,854,529
Securities Available for Sale, Estimated Fair Value [Abstract]
Due in one year or less	22,623
Due after one year through five years	1,614
Due after five years through ten years	2,513
Due after ten years	21,042
Total fair value, before mortgage-backed securities	47,792
Mortgage-backed securities	1,554,612
Total	1,602,404	1,811,813
Securities Held to Maturity, Amortized Cost [Abstract]
Due in one year or less	5,071
Due after one year through five years	30,491
Due after five years through ten years	0
Due after ten years	0
Total amortized cost, before mortgage-backed securities	35,562
Mortgage-backed securities	702,537
Securities Held to Maturity, Amortized Cost	738,099	909,643
Securities Held to Maturity, Estimated Fair Value [Abstract]
Due in one year or less	5,115
Due after one year through five years	31,048
Due after five years through ten years	0
Due after ten years	0
Total fair value, before mortgage-backed securities	36,163
Mortgage-backed securities	710,039
Total	$ 746,202	$ 889,733

Loans Held for Investment (LH_3

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Loan Portfolio Held for Investment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Loan Portfolio [Abstract]
Total LHFI	$ 9,335,628	$ 8,835,868
Less allowance for loan losses, LHFI	84,277	79,290
Net LHFI	9,251,351	8,756,578
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	1,162,791	1,056,601
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	1,855,913	1,825,492
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	724,480	543,820
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	2,475,245	2,220,914
Commercial and Industrial Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	1,477,896	1,538,715
Consumer Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	175,738	182,448
State and Other Political Subdivision Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	967,944	973,818
Other Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	$ 495,621	$ 494,060

Loans Held for Investment (LH_4

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Additional Information (Details 1)	12 Months Ended
	Dec. 31, 2019USD ($)Region	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Accounts Notes Loans And Financing Receivable Gross Allowance And Net [Abstract]
Maximum concentration of loan as a percentage of total LHFI	10.00%
Key market regions | Region	5
Loans and Leases Receivable, Related Parties	$ 35,500,000	$ 49,000,000
New loan advances to related party	464,600,000
Loan repayment by related party	478,100,000
Loan increase (decreases) from changes in executive officers and directors	0
Minimum loan amount for loan to be specifically reviewed for impairment and deemed impaired	500,000
LHFI Classified as TDRs	31,500,000	28,200,000	$ 23,900,000
LHFI classified as TDRs from credits with interest only payments	20,800,000	23,800,000	20,500,000
Unused Commitments on TDRs	7,000,000	4,400,000	0
Financing receivable, related allowance	3,200,000	2,300,000	458,000
Financing receivable, related charge-offs	$ 1,600,000	$ 18,400,000	$ 127,000

Loans Held for Investment (LH_5

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Aging Analysis of Past Due and Nonaccrual LHFI by Loan Type (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		$ 12,627	$ 17,691
Nonaccrual		53,226	61,624
Current Loans		9,269,775	8,756,553
Total LHFI		9,335,628	8,835,868
Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		10,393	14,383
Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		1,592	2,452
Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	[1]	642	856
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		636	284
Nonaccrual		897	2,218
Current Loans		1,161,258	1,054,099
Total LHFI		1,162,791	1,056,601
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		380	284
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		256
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		6,405	10,869
Nonaccrual		16,810	14,718
Current Loans		1,832,698	1,799,905
Total LHFI		1,855,913	1,825,492
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		5,254	8,600
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		940	1,700
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	[1]	211	569
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		1,698	1,887
Nonaccrual		7,700	9,621
Current Loans		2,465,847	2,209,406
Total LHFI		2,475,245	2,220,914
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		1,698	1,887
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		8	296
Nonaccrual		1,032	927
Current Loans		723,440	542,597
Total LHFI		724,480	543,820
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		8	197
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due			99
Commercial and Industrial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		668	1,646
Nonaccrual		21,775	23,938
Current Loans		1,455,453	1,513,131
Total LHFI		1,477,896	1,538,715
Commercial and Industrial Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		617	1,346
Commercial and Industrial Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		12	300
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	[1]	39
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		2,980	2,440
Nonaccrual		108	205
Current Loans		172,650	179,803
Total LHFI		175,738	182,448
Consumer Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		2,208	1,800
Consumer Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		380	353
Consumer Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	[1]	392	287
State and Other Political Subdivision Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		76	186
Nonaccrual		4,079	8,595
Current Loans		963,789	965,037
Total LHFI		967,944	973,818
State and Other Political Subdivision Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		76	186
Other Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		156	83
Nonaccrual		825	1,402
Current Loans		494,640	492,575
Total LHFI		495,621	494,060
Other Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		152	$ 83
Other Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		$ 4
[1]	Past due 90 days or more but still accruing interest.

Loans Held for Investment (LH_6

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	$ 47,289	$ 62,921
Total LHFI With No Related Allowance Recorded	23,550	25,553
Total LHFI With an Allowance Recorded	17,667	30,282
Total LHFI Carrying Amount	41,217	55,835
Related Allowance	5,459	6,354
Average Recorded Investment	48,525	46,920
Commercial and Industrial Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	27,178	37,786
Total LHFI With No Related Allowance Recorded	19,374	12,893
Total LHFI With an Allowance Recorded	4,084	17,824
Total LHFI Carrying Amount	23,458	30,717
Related Allowance	707	4,334
Average Recorded Investment	27,088	26,725
Consumer Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	22	2
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	21	2
Total LHFI Carrying Amount	21	2
Related Allowance	0	0
Average Recorded Investment	11	6
State and Other Political Subdivision Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	4,079	8,688
Total LHFI With No Related Allowance Recorded	0	4,079
Total LHFI With an Allowance Recorded	4,079	4,516
Total LHFI Carrying Amount	4,079	8,595
Related Allowance	1,809	516
Average Recorded Investment	6,337	4,297
Other Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	1,207	1,418
Total LHFI With No Related Allowance Recorded	0	230
Total LHFI With an Allowance Recorded	784	1,052
Total LHFI Carrying Amount	784	1,282
Related Allowance	553	1,052
Average Recorded Investment	1,033	804
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	926	1,794
Total LHFI With No Related Allowance Recorded	610	1,528
Total LHFI With an Allowance Recorded	16	24
Total LHFI Carrying Amount	626	1,552
Related Allowance	0	0
Average Recorded Investment	1,089	1,738
Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	6,513	4,951
Total LHFI With No Related Allowance Recorded	2,104	95
Total LHFI With an Allowance Recorded	3,360	3,868
Total LHFI Carrying Amount	5,464	3,963
Related Allowance	35	39
Average Recorded Investment	4,713	4,328
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	7,295	8,282
Total LHFI With No Related Allowance Recorded	1,462	6,728
Total LHFI With an Allowance Recorded	5,255	2,748
Total LHFI Carrying Amount	6,717	9,476
Related Allowance	2,355	413
Average Recorded Investment	8,096	8,898
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	69	0
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	68	248
Total LHFI Carrying Amount	68	248
Related Allowance	0	0
Average Recorded Investment	$ 158	$ 124

Loans Held for Investment (LH_7

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Impact of Modifications Classified as Troubled Debt Restructurings (Details) - Troubled Debt Restructurings [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)Contract	Dec. 31, 2018USD ($)Contract	Dec. 31, 2017USD ($)Contract
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	30	52	33
Pre-Modification Outstanding Recorded Investment	$ 15,994	$ 30,878	$ 15,637
Post-Modification Outstanding Recorded Investment	$ 15,877	$ 29,328	$ 15,630
Secured by 1-4 Family Residential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	19	23	22
Pre-Modification Outstanding Recorded Investment	$ 1,742	$ 2,102	$ 1,478
Post-Modification Outstanding Recorded Investment	$ 1,738	$ 1,660	$ 1,487
Secured by Nonfarm, Nonresidential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	1	2	1
Pre-Modification Outstanding Recorded Investment	$ 5,055	$ 1,780	$ 426
Post-Modification Outstanding Recorded Investment	$ 5,055	$ 1,780	$ 426
Commercial and Industrial Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	8	23	8
Pre-Modification Outstanding Recorded Investment	$ 9,167	$ 26,970	$ 12,836
Post-Modification Outstanding Recorded Investment	$ 9,054	$ 25,862	$ 12,836
Consumer Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	2	3
Pre-Modification Outstanding Recorded Investment	$ 30	$ 4
Post-Modification Outstanding Recorded Investment	$ 30	$ 4
Construction, Land Development and Other Land [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract		1	1
Pre-Modification Outstanding Recorded Investment		$ 22	$ 341
Post-Modification Outstanding Recorded Investment		$ 22	$ 325
Other Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract			1
Pre-Modification Outstanding Recorded Investment			$ 556
Post-Modification Outstanding Recorded Investment			$ 556

Loans Held for Investment (LH_8

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Troubled Debt Restructuring Subsequently Defaulted (Details) - Troubled Debt Restructurings that Subsequently Defaulted [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)Contract	Dec. 31, 2018USD ($)Contract	Dec. 31, 2017USD ($)Contract
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	11	13	7
Recorded Investment | $	$ 665	$ 15,935	$ 9,604
Construction, Land Development and Other Land [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract		1
Recorded Investment | $		$ 22
Secured by 1-4 Family Residential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	3	5	4
Recorded Investment | $	$ 446	$ 734	$ 78
Commercial and Industrial Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	7	6	3
Recorded Investment | $	$ 192	$ 15,178	$ 9,526
Consumer Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	1	1
Recorded Investment | $	$ 27	$ 1

Loans Held for Investment (LH_9

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Troubled Debt Restructuring Related to Loans Held for Investment, Excluding Covered Loans, by Loan Type (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable Modifications [Line Items]
Nonaccrual	$ 53,226	$ 61,624
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	897	2,218
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	16,810	14,718
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	7,700	9,621
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	1,032	927
Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	21,775	23,938
Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	108	205
Other Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	825	1,402
Troubled Debt Restructurings [Member]
Financing Receivable Modifications [Line Items]
Accruing	3,396	11,484	$ 660
Nonaccrual	28,127	16,706	23,211
Total	31,523	28,190	23,871
Troubled Debt Restructurings [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0	0
Nonaccrual	15	24	199
Total	15	24	199
Troubled Debt Restructurings [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	77	743	51
Nonaccrual	3,865	3,125	3,140
Total	3,942	3,868	3,191
Troubled Debt Restructurings [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	1,734	0
Nonaccrual	5,176	395	421
Total	5,176	2,129	421
Troubled Debt Restructurings [Member] | Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	3,319	9,007	53
Nonaccrual	18,913	12,620	19,434
Total	22,232	21,627	19,487
Troubled Debt Restructurings [Member] | Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0	0
Nonaccrual	21	2	17
Total	21	2	17
Troubled Debt Restructurings [Member] | Other Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0	556
Nonaccrual	137	540	0
Total	$ 137	$ 540	$ 556

Loans Held for Investment (L_10

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Additional Information (Details 2)	12 Months Ended
	Dec. 31, 2019USD ($)KeyRatioLoanPoolCreditRiskGrade	Dec. 31, 2018USD ($)
Financing Receivable, Recorded Investment, Aging [Abstract]
Number of key quality ratios | KeyRatio	6
LHFS past due 90 days or more	$ 41,600,000	$ 37,400,000
Financing Receivable [Abstract]
Number of primary commercial loan groups | LoanPool	9
Number of individual credit risk grades | CreditRiskGrade	10
Minimum [Member]
Financing Receivable [Abstract]
Period to conduct asset review	6 months
Credit amount used as baseline in evaluating loan policy	$ 100,000
Maximum [Member]
Financing Receivable [Abstract]
Period to conduct asset review	18 months

Loans Held for Investment (L_11

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Summary of LHFI by Loan Type and Credit Quality Indicator (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable [Abstract]
Current		$ 9,269,775	$ 8,756,553
Financing Receivable, Recorded Investment, Past Due		12,627	17,691
Nonaccrual		53,226	61,624
Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due	[1]	642	856
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current		1,832,698	1,799,905
Financing Receivable, Recorded Investment, Past Due		6,405	10,869
Nonaccrual		16,810	14,718
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due	[1]	211	569
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current		2,465,847	2,209,406
Financing Receivable, Recorded Investment, Past Due		1,698	1,887
Nonaccrual		7,700	9,621
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current		723,440	542,597
Financing Receivable, Recorded Investment, Past Due		8	296
Nonaccrual		1,032	927
Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Current		1,455,453	1,513,131
Financing Receivable, Recorded Investment, Past Due		668	1,646
Nonaccrual		21,775	23,938
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due	[1]	39
Consumer Loans [Member]
Financing Receivable [Abstract]
Current		172,650	179,803
Financing Receivable, Recorded Investment, Past Due		2,980	2,440
Nonaccrual		108	205
Consumer Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due	[1]	392	287
State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Current		963,789	965,037
Financing Receivable, Recorded Investment, Past Due		76	186
Nonaccrual		4,079	8,595
Other Loans [Member]
Financing Receivable [Abstract]
Current		494,640	492,575
Financing Receivable, Recorded Investment, Past Due		156	83
Nonaccrual		825	1,402
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current		1,161,258	1,054,099
Financing Receivable, Recorded Investment, Past Due		636	284
Nonaccrual		897	2,218
Commercial LHFI [Member]
Financing Receivable [Abstract]
Financing receivable commercial		7,348,158	6,879,655
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		123,033	126,367
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		2,475,090	2,220,854
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		723,785	542,891
Commercial LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,477,896	1,538,715
Commercial LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		967,944	973,818
Commercial LHFI [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		489,496	488,782
Commercial LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,090,914	988,228
Commercial LHFI [Member] | Pass [Member]
Financing Receivable [Abstract]
Financing receivable commercial		7,178,617	6,712,604
Commercial LHFI [Member] | Pass [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		116,592	123,191
Commercial LHFI [Member] | Pass [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		2,430,761	2,182,106
Commercial LHFI [Member] | Pass [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		721,238	537,958
Commercial LHFI [Member] | Pass [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,407,837	1,468,262
Commercial LHFI [Member] | Pass [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		957,948	958,214
Commercial LHFI [Member] | Pass [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		469,095	460,568
Commercial LHFI [Member] | Pass [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,075,146	982,305
Commercial LHFI [Member] | Special Mention [Member]
Financing Receivable [Abstract]
Financing receivable commercial		9,049	37,387
Commercial LHFI [Member] | Special Mention [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		45	216
Commercial LHFI [Member] | Special Mention [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial			1,250
Commercial LHFI [Member] | Special Mention [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial			323
Commercial LHFI [Member] | Special Mention [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		909	12,431
Commercial LHFI [Member] | Special Mention [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		4,650	5,250
Commercial LHFI [Member] | Special Mention [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		3,445	17,842
Commercial LHFI [Member] | Special Mention [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial			75
Commercial LHFI [Member] | Substandard [Member]
Financing Receivable [Abstract]
Financing receivable commercial		159,163	126,631
Commercial LHFI [Member] | Substandard [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		6,355	2,731
Commercial LHFI [Member] | Substandard [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		44,001	37,025
Commercial LHFI [Member] | Substandard [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		2,547	4,610
Commercial LHFI [Member] | Substandard [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		68,262	55,943
Commercial LHFI [Member] | Substandard [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		5,346	10,354
Commercial LHFI [Member] | Substandard [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		16,926	10,323
Commercial LHFI [Member] | Substandard [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		15,726	5,645
Commercial LHFI [Member] | Doubtful [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,329	3,033
Commercial LHFI [Member] | Doubtful [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		41	229
Commercial LHFI [Member] | Doubtful [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		328	473
Commercial LHFI [Member] | Doubtful [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		888	2,079
Commercial LHFI [Member] | Doubtful [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		30	49
Commercial LHFI [Member] | Doubtful [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		42	203
Consumer LHFI [Member]
Financing Receivable [Abstract]
Financing receivable commercial		9,335,628	8,835,868
Current		1,961,967	1,929,437
Nonaccrual		16,057	13,770
Subtotal		1,987,470	1,956,213
Consumer LHFI [Member] | Past Due 30-89 Days [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		8,842	12,149
Consumer LHFI [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		604	857
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,855,913	1,825,492
Current		1,710,930	1,675,455
Nonaccrual		15,817	13,229
Subtotal		1,732,880	1,699,125
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30-89 Days [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		5,922	9,872
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		211	569
Consumer LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		2,475,245	2,220,914
Current		155	60
Subtotal		155	60
Consumer LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		724,480	543,820
Current		695	929
Subtotal		695	929
Consumer LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,477,896	1,538,715
Consumer LHFI [Member] | Consumer Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		175,738	182,448
Current		172,649	179,802
Nonaccrual		108	205
Subtotal		175,738	182,448
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 30-89 Days [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		2,588	2,153
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		393	288
Consumer LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		967,944	973,818
Consumer LHFI [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		495,621	494,060
Current		6,125	5,278
Subtotal		6,125	5,278
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,162,791	1,056,601
Current		71,413	67,913
Nonaccrual		132	336
Subtotal		71,877	68,373
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 30-89 Days [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		$ 332	$ 124
[1]	Past due 90 days or more but still accruing interest.

Loans Held for Investment (L_12

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Additional Information (Details 3)	12 Months Ended
	Dec. 31, 2019FactorLoanScale
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Number of loan types for commercial portfolio | Loan	9
Number of risk rate factors for commercial loans | Factor	450
Minimum score for qualitative risk factor | Scale	0
Maximum score for qualitative risk factor | Scale	100
Number of loan types for consumer portfolio | Loan	5
Number of unique qualitative factors used to analyze consumer loans | Factor	5

Loans Held for Investment (L_13

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Summary of Balance in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	$ 5,500	$ 6,400
Total	84,277	79,290
Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	5,459	6,354
Collectively	78,818	72,936
Total	84,277	79,290	$ 76,733	$ 71,265
Allowance for Loan Losses, LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	707	4,334
Collectively	25,285	23,025
Total	25,992	27,359	22,851
Allowance for Loan Losses, LHFI [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively	3,379	2,890
Total	3,379	2,890	3,470
Allowance for Loan Losses, LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	1,809	516
Collectively	420	474
Total	2,229	990	789
Allowance for Loan Losses, LHFI [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	553	1,052
Collectively	4,750	5,142
Total	5,303	6,194	4,666
Allowance for Loan Losses, LHFI [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively	8,260	7,390
Total	8,260	7,390	7,865
Allowance for Loan Losses, LHFI [Member] | Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	35	39
Collectively	8,897	8,602
Total	8,932	8,641	10,874
Allowance for Loan Losses, LHFI [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	2,355	413
Collectively	23,803	21,963
Total	26,158	22,376	23,428
Allowance for Loan Losses, LHFI [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively	4,024	3,450
Total	$ 4,024	$ 3,450	$ 2,790

Loans Held for Investment (L_14

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Summary of Loan Type Related to Each Balance in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	$ 41,200	$ 55,800
Total LHFI	9,335,628	8,835,868
Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	41,217	55,835
LHFI, Collectively Evaluated For Impairment	9,294,411	8,780,033
Total LHFI	9,335,628	8,835,868
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	1,162,791	1,056,601
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	626	1,552
LHFI, Collectively Evaluated For Impairment	1,162,165	1,055,049
Total LHFI	1,162,791	1,056,601
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	1,855,913	1,825,492
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	5,464	3,963
LHFI, Collectively Evaluated For Impairment	1,850,449	1,821,529
Total LHFI	1,855,913	1,825,492
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	2,475,245	2,220,914
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	6,717	9,476
LHFI, Collectively Evaluated For Impairment	2,468,528	2,211,438
Total LHFI	2,475,245	2,220,914
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	724,480	543,820
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	68	248
LHFI, Collectively Evaluated For Impairment	724,412	543,572
Total LHFI	724,480	543,820
Commercial and Industrial Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	1,477,896	1,538,715
Commercial and Industrial Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	23,458	30,717
LHFI, Collectively Evaluated For Impairment	1,454,438	1,507,998
Total LHFI	1,477,896	1,538,715
Consumer Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	175,738	182,448
Consumer Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	21	2
LHFI, Collectively Evaluated For Impairment	175,717	182,446
Total LHFI	175,738	182,448
State and Other Political Subdivision Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	967,944	973,818
State and Other Political Subdivision Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	4,079	8,595
LHFI, Collectively Evaluated For Impairment	963,865	965,223
Total LHFI	967,944	973,818
Other Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	495,621	494,060
Other Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	784	1,282
LHFI, Collectively Evaluated For Impairment	494,837	492,778
Total LHFI	$ 495,621	$ 494,060

Loans Held for Investment (L_15

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Change in Allowance for Loan Losses (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		$ 79,290
Provision for loan losses, LHFI		10,797	$ 17,993	$ 15,094
Balance at end of period		84,277	79,290
Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		79,290	76,733	71,265
Transfers	[1]		1,554
Loans charged-off		(14,481)	(29,489)	(21,147)
Recoveries		8,671	12,499	11,521
Net (charge-offs) recoveries		(5,810)	(16,990)	(9,626)
Provision for loan losses, LHFI		10,797	17,993	15,094
Balance at end of period		84,277	79,290	76,733
Allowance for Loan Losses, LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		7,390	7,865
Transfers	[1]		584
Loans charged-off		(40)	(123)
Recoveries		894	1,124
Provision for loan losses, LHFI		16	(2,060)
Balance at end of period		8,260	7,390	7,865
Allowance for Loan Losses, LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		8,641	10,874
Transfers	[1]		182
Loans charged-off		(531)	(1,629)
Recoveries		666	646
Provision for loan losses, LHFI		156	(1,432)
Balance at end of period		8,932	8,641	10,874
Allowance for Loan Losses, LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		22,376	23,428
Transfers	[1]		446
Loans charged-off		(322)	(1,184)
Recoveries		472	133
Provision for loan losses, LHFI		3,632	(447)
Balance at end of period		26,158	22,376	23,428
Allowance for Loan Losses, LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		3,450	2,790
Transfers	[1]		291
Recoveries		29	23
Provision for loan losses, LHFI		545	346
Balance at end of period		4,024	3,450	2,790
Allowance for Loan Losses, LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		27,359	22,851
Transfers	[1]		46
Loans charged-off		(5,344)	(18,823)
Recoveries		1,257	5,410
Provision for loan losses, LHFI		2,720	17,875
Balance at end of period		25,992	27,359	22,851
Allowance for Loan Losses, LHFI [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		2,890	3,470
Transfers	[1]		5
Loans charged-off		(2,278)	(2,089)
Recoveries		1,829	2,019
Provision for loan losses, LHFI		938	(515)
Balance at end of period		3,379	2,890	3,470
Allowance for Loan Losses, LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		990	789
Provision for loan losses, LHFI		1,239	201
Balance at end of period		2,229	990	789
Allowance for Loan Losses, LHFI [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		6,194	4,666
Loans charged-off		(5,966)	(5,641)
Recoveries		3,524	3,144
Provision for loan losses, LHFI		1,551	4,025
Balance at end of period		$ 5,303	$ 6,194	$ 4,666
[1]	The allowance for loan losses balance related to the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions, which were transferred from acquired impaired loans to LHFI during 2018.

Acquired Loans - Schedule of Ac

Acquired Loans - Schedule of Acquired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	$ 72,601	$ 106,932
Less allowance for loan losses, acquired loans	815	1,231	$ 4,079	$ 11,397
Net acquired loans	71,786	105,701
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	4,771	5,878
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	17,525	22,556
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	38,206	47,979
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	3,946	8,253
Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	5,035	15,267
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	520	1,356
Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	$ 2,598	$ 5,643

Acquired Loans - Changes in the

Acquired Loans - Changes in the Carrying Value of Acquired Loans (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		$ 105,701
Accretion to interest income		5,532	$ 9,514		$ 14,924
Carrying value, net, ending		71,786	105,701
Acquired Not ASC 310-30 [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning	[1]	2,811	77,868
Transfers	[1],[2]	(2,926)	(59,916)	[3]
Accretion to interest income	[1]	115	1,019
Payments received, net	[1]	0	(16,234)
Other	[1],[4]	0	74
Change in allowance for loan losses, acquired loans	[1]	0	0
Carrying value, net, ending	[1]	0	2,811		77,868
Acquired Impaired [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		102,890	179,570
Transfers	[2]	0	(26,497)	[3]
Accretion to interest income		5,532	9,514
Payments received, net		(37,230)	(62,519)
Other	[4]	178	(26)
Change in allowance for loan losses, acquired loans		416	2,848
Carrying value, net, ending		$ 71,786	$ 102,890		$ 179,570
[1]	“Acquired Not ASC 310-30” loans consist of loans that are not in scope for FASB ASC Subtopic 310-30.
[2]	“Acquired Not ASC 310-30” loans transferred to LHFI due to the discount on these loans being fully amortized.
[3]	During 2018, Trustmark transferred the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions from acquired impaired loans to LHFI.
[4]	Includes miscellaneous timing adjustments as well as acquired loan terminations through foreclosure, charge-off and other terminations.

Acquired Loans - Changes in Acc

Acquired Loans - Changes in Accretable Yield of Acquired Loans (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in accretable difference on acquired loans [Abstract]
Accretable yield at beginning of period		$ (17,722)	$ (31,426)	$ (38,918)
Additions due to acquisition	[1]	0	0	(784)
Accretion to interest income		5,532	9,514	14,924
Disposals, net		2,072	3,926	2,868
Transfers	[2]	0	5,874	0
Reclassification from nonaccretable difference	[3]	(4,698)	(5,610)	(9,516)
Accretable yield at end of period		$ (14,816)	$ (17,722)	$ (31,426)
[1]	Accretable yield on loans acquired from Reliance on April 7, 2017.
[2]	During 2018, Trustmark transferred the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions from acquired impaired loans to LHFI.
[3]	Reclassifications from nonaccretable difference are due to lower loss expectations and improvements in expected cash flows.

Acquired Loans - Components of

Acquired Loans - Components of the Allowance for Loan Losses on Acquired Loans (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period		$ 1,231	$ 4,079	$ 11,397
Transfers	[1]	0	(1,554)	0
Provision for loan losses, acquired loans		42	(1,005)	(7,395)
Net (charge-offs) recoveries		(458)	(289)	77
Balance at end of period		$ 815	$ 1,231	$ 4,079
[1]	The allowance for loan losses balance related to the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions, which were transferred from acquired impaired loans to LHFI during 2018.

Acquired Loans - Additional Inf

Acquired Loans - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019CreditRiskGrade
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities [Abstract]
Number of individual credit risk grades	10

Acquired Loans - Acquired Loans

Acquired Loans - Acquired Loans by Loan Type and Credit Quality Indicator (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		$ 71,786	$ 105,701
Acquired Loans, Aging [Abstract]
Current		70,305	104,377
Acquired Loans, Past Due		2,296	2,555
Nonaccrual	[1]	0	0
Total Acquired Loans		72,601	106,932
Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	1,307	1,546
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		4,639	5,786
Acquired Loans, Past Due		132	92
Nonaccrual	[1]	0	0
Total Acquired Loans		4,771	5,878
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	38	87
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		16,332	21,303
Acquired Loans, Past Due		1,193	1,253
Nonaccrual	[1]	0	0
Total Acquired Loans		17,525	22,556
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	366	481
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		37,319	46,795
Acquired Loans, Past Due		887	1,184
Nonaccrual	[1]	0	0
Total Acquired Loans		38,206	47,979
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	851	978
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		3,893	8,237
Acquired Loans, Past Due		53	16
Nonaccrual	[1]	0	0
Total Acquired Loans		3,946	8,253
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	52	0
Commercial and Industrial Loans [Member]
Acquired Loans, Aging [Abstract]
Current		5,035	15,267
Acquired Loans, Past Due		0	0
Nonaccrual	[1]	0	0
Total Acquired Loans		5,035	15,267
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	0	0
Consumer Loans [Member]
Acquired Loans, Aging [Abstract]
Current		489	1,346
Acquired Loans, Past Due		31	10
Nonaccrual	[1]	0	0
Total Acquired Loans		520	1,356
Consumer Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	0	0
Other Loans [Member]
Acquired Loans, Aging [Abstract]
Current		2,598	5,643
Acquired Loans, Past Due		0	0
Nonaccrual	[1]	0	0
Total Acquired Loans		2,598	5,643
Other Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	0	0
Commercial LHFI [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		57,785	87,740
Commercial LHFI [Member] | Pass [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		44,922	62,437
Commercial LHFI [Member] | Special Mention [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		42	71
Commercial LHFI [Member] | Substandard [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		10,819	22,174
Commercial LHFI [Member] | Doubtful [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		2,002	3,058
Commercial LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		4,214	5,227
Commercial LHFI [Member] | Construction, Land Development and Other Land [Member] | Pass [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		4,022	4,923
Commercial LHFI [Member] | Construction, Land Development and Other Land [Member] | Special Mention [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans			26
Commercial LHFI [Member] | Construction, Land Development and Other Land [Member] | Substandard [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		192	278
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		3,786	5,371
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Pass [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		3,164	4,341
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Special Mention [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		42	45
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Substandard [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		580	534
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Doubtful [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans			451
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		38,206	47,979
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Pass [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		27,848	34,933
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Substandard [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		9,972	12,614
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Doubtful [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		386	432
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		3,946	8,253
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Pass [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		3,878	7,653
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Substandard [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		68	190
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Doubtful [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans			410
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		5,035	15,267
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Pass [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		3,419	6,560
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Substandard [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans			6,942
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Doubtful [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		1,616	1,765
Commercial LHFI [Member] | Other Loans [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		2,598	5,643
Commercial LHFI [Member] | Other Loans [Member] | Pass [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		2,591	4,027
Commercial LHFI [Member] | Other Loans [Member] | Substandard [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		7	1,616
Consumer LHFI [Member]
Acquired Loans, Aging [Abstract]
Current		13,795	18,121
Subtotal		14,816	19,192
Total Acquired Loans		72,601	106,932
Consumer LHFI [Member] | Past Due 30-89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		740	586
Consumer LHFI [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		281	485
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		463	642
Subtotal		557	651
Total Acquired Loans		4,771	5,878
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 30-89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		94	5
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due			4
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		12,843	16,133
Subtotal		13,739	17,185
Total Acquired Loans		17,525	22,556
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30-89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		615	571
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		281	481
Consumer LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Total Acquired Loans		38,206	47,979
Consumer LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Total Acquired Loans		3,946	8,253
Consumer LHFI [Member] | Commercial and Industrial Loans [Member]
Acquired Loans, Aging [Abstract]
Total Acquired Loans		5,035	15,267
Consumer LHFI [Member] | Consumer Loans [Member]
Acquired Loans, Aging [Abstract]
Current		489	1,346
Subtotal		520	1,356
Total Acquired Loans		520	1,356
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 30-89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		31	10
Consumer LHFI [Member] | Other Loans [Member]
Acquired Loans, Aging [Abstract]
Total Acquired Loans		$ 2,598	$ 5,643
[1]	Acquired loans not accounted for under FASB ASC Subtopic 310-30.
[2]	Past due 90 days or more but still accruing interest.

Acquired Loans - Aging Analysis

Acquired Loans - Aging Analysis of Past Due and Nonaccrual Acquired Loans, by Class (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		$ 2,296	$ 2,555
Nonaccrual	[1]	0	0
Current		70,305	104,377
Acquired Loans		72,601	106,932
Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		843	878
Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		146	131
Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	1,307	1,546
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		132	92
Nonaccrual	[1]	0	0
Current		4,639	5,786
Acquired Loans		4,771	5,878
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		94	5
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		0	0
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	38	87
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		1,193	1,253
Nonaccrual	[1]	0	0
Current		16,332	21,303
Acquired Loans		17,525	22,556
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		696	664
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		131	108
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	366	481
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		887	1,184
Nonaccrual	[1]	0	0
Current		37,319	46,795
Acquired Loans		38,206	47,979
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		36	206
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		0	0
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	851	978
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		53	16
Nonaccrual	[1]	0	0
Current		3,893	8,237
Acquired Loans		3,946	8,253
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		1	2
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		0	14
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	52	0
Commercial and Industrial Loans [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		0	0
Nonaccrual	[1]	0	0
Current		5,035	15,267
Acquired Loans		5,035	15,267
Commercial and Industrial Loans [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		0	0
Commercial and Industrial Loans [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		0	0
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	0	0
Consumer Loans [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		31	10
Nonaccrual	[1]	0	0
Current		489	1,346
Acquired Loans		520	1,356
Consumer Loans [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		16	1
Consumer Loans [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		15	9
Consumer Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	0	0
Other Loans [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		0	0
Nonaccrual	[1]	0	0
Current		2,598	5,643
Acquired Loans		2,598	5,643
Other Loans [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		0	0
Other Loans [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		0	0
Other Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	$ 0	$ 0
[1]	Acquired loans not accounted for under FASB ASC Subtopic 310-30.
[2]	Past due 90 days or more but still accruing interest.

Premises and Equipment, Net - P

Premises and Equipment, Net - Premises and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	$ 437,073		$ 425,343
Less accumulated depreciation and amortization	256,608		247,160
Premises and equipment, net	180,465		178,183
Financing lease right-of-use assets	9,326	$ 11,200	0
Assets held for sale	0		485
Total premises and equipment, net	189,791		178,668
Land [Member]
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	52,454		52,779
Building and Leasehold Improvements [Member]
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	210,362		202,912
Furniture and Equipment [Member]
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	$ 174,257		$ 169,652

Premises and Equipment, Net - A

Premises and Equipment, Net - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)Branch	Dec. 31, 2018USD ($)Branch	Dec. 31, 2017USD ($)
Property Plant And Equipment [Abstract]
Number of branches held for sale | Branch	0	3
Property valuation adjustments	$ 0	$ 173	$ 338
Premises and Equipment, Net, by Type [Abstract]
Depreciation and amortization of premises and equipment	$ 15,700	$ 14,300	$ 14,300

Mortgage Banking - Schedule of

Mortgage Banking - Schedule of Activity in the Mortgage Servicing Rights (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Mortgage servicing rights [Abstract]
Balance at beginning of period	$ 95,596	$ 84,269
Origination of servicing assets	16,711	15,759
Change in fair value [Abstract]
Due to market changes	(21,078)	7,342
Due to runoff	(11,835)	(11,774)
Balance at end of period	$ 79,394	$ 95,596

Mortgage Banking - Additional I

Mortgage Banking - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)CPR	Dec. 31, 2018USD ($)CPR	Dec. 31, 2017USD ($)
Schedule of changes in the reserve for mortgage loan [Abstract]
Assumed average prepayment speed | CPR	11	8
Average discount rate (in hundredths)	10.03%	10.04%
Annual servicing fee	$ 22,600	$ 21,900	$ 21,400
Servicing fee income percentage of outstanding balance of underlying loans (in hundredths)	0.32%
Mortgage servicing rights [Abstract]
Residential mortgage loans sold	$ 1,404,000	1,092,000	1,179,000
Gains on sales of residential mortgage loans	$ 30,300	21,800	$ 18,800
Period of putback response	60 days
Reserve for mortgage loan servicing putback expenses	$ 500	$ 1,000

Mortgage Banking - Schedule o_2

Mortgage Banking - Schedule of Mortgage Loans Sold and Serviced for Others (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	$ 7,157,234	$ 6,834,874
Federal National Mortgage Association [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	4,411,914	4,204,336
Government National Mortgage Association [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	2,652,782	2,537,238
Federal Home Loan Mortgage Corporation [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	73,134	71,343
Other [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	$ 19,404	$ 21,957

Goodwill and Identifiable Int_3

Goodwill and Identifiable Intangible Assets - Goodwill by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 379,627	$ 379,627
Adjustment	0	0
Balance, end of period	379,627	379,627
General Banking [Member]
Goodwill [Roll Forward]
Goodwill, beginning of period	334,603	334,603
Adjustment	0	0
Balance, end of period	334,603	334,603
Insurance [Member]
Goodwill [Roll Forward]
Goodwill, beginning of period	45,024	45,024
Adjustment	0	0
Balance, end of period	$ 45,024	$ 45,024

Goodwill and Identifiable Int_4

Goodwill and Identifiable Intangible Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Amortization expense of identifiable intangible assets	$ 4,100,000	$ 5,200,000	$ 6,200,000
Impairment losses on identifiable intangible assets	0	0	0
Future amortization expense for identifiable intangible assets [Abstract]
2020	2,800,000
2021	2,000,000
2022	1,200,000
2023	411,000
2024	224,000
General Banking And Insurance [Member]
Goodwill [Line Items]
Impairment charge	$ 0	$ 0	$ 0

Goodwill and Identifiable Int_5

Goodwill and Identifiable Intangible Assets - Schedule of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 103,170	$ 102,823
Accumulated Amortization	95,827	91,711
Net Carrying Amount	$ 7,343	11,112
Remaining Weighted-Average Amortization Periods in Years	5 years 8 months 12 days
Core Deposit Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 87,674	87,674
Accumulated Amortization	82,096	78,353
Net Carrying Amount	$ 5,578	9,321
Remaining Weighted-Average Amortization Periods in Years	3 years 9 months 18 days
Insurance Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 14,171	13,824
Accumulated Amortization	12,655	12,348
Net Carrying Amount	$ 1,516	1,476
Remaining Weighted-Average Amortization Periods in Years	12 years 10 months 24 days
Banking Charters [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,325	1,325
Accumulated Amortization	1,076	1,010
Net Carrying Amount	$ 249	$ 315
Remaining Weighted-Average Amortization Periods in Years	3 years 8 months 12 days

Other Real Estate - Changes and

Other Real Estate - Changes and Gains (Losses), Net on Other Real Estate (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation Of Carrying Amount Of Real Estate Investments Roll Forward
Balance at beginning of period		$ 34,668	$ 43,228	$ 62,051
Additions	[1]	8,598	12,115	9,235
Disposals		(11,474)	(19,802)	(24,762)
Write-downs		(2,544)	(873)	(3,296)
Balance at end of period		29,248	34,668	43,228
Gain (losses), net on the sale of other real estate included in other real estate expense		$ (291)	$ 700	$ 2,087
[1]	For the year ended December 31, 2017, additions to other real estate included $475 thousand of other real estate acquired in the Reliance merger on April 7, 2017

Other Real Estate - Changes a_2

Other Real Estate - Changes and Gains (Losses), Net on Other Real Estate (Parenthetical) (Details) $ in Thousands	Apr. 07, 2017USD ($)
Reliance [Member]
Business Acquisition [Line Items]
Other real estate	$ 475

Other Real Estate - Other Real

Other Real Estate - Other Real Estate, By Type of Property (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	$ 29,248	$ 34,668	$ 43,228	$ 62,051
Construction, Land Development And Other Land Properties [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	11,482	16,206
1 - 4 Family Residential Properties [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	3,453	4,983
Nonfarm, Nonresidential Properties [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	$ 14,313	13,296
Other Real Estate Properties [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate		$ 183

Other Real Estate - Other Rea_2

Other Real Estate - Other Real Estate, By Geographic Location (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other real estate, excluding covered other real estate [Line Items]
Total other real estate		$ 29,248	$ 34,668	$ 43,228	$ 62,051
Alabama [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate		8,133	6,873
Florida [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate		5,877	8,771
Mississippi [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	[1]	14,919	17,255
Tennessee [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	[2]	$ 319	1,025
Texas [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate			$ 744
[1]	Mississippi includes Central and Southern Mississippi Regions.
[2]	Tennessee includes Memphis, Tennessee and Northern Mississippi Regions.

Other Real Estate - Additional

Other Real Estate - Additional information (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Reconciliation Of Carrying Amount Of Real Estate Investments Roll Forward
Foreclosed residential real estate properties recorded as a result of obtaining physical possession of property	$ 3,500	$ 5,000
Consumer mortgage loans and that formal foreclosure proceedings are in process	$ 953	$ 1,100

Leases - Components of Net Leas

Leases - Components of Net Lease Cost (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Finance leases
Amortization of right-of-use assets	$ 2,162
Interest on lease liabilities	307
Operating lease cost	5,183
Short-term lease cost	370
Variable lease cost	1,387
Sublease income	(331)
Net lease cost	$ 9,078

Leases - Cash Payments Included

Leases - Cash Payments Included in Measurement of Lease liabilities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Finance leases
Operating cash flows included in operating activities	$ 307
Financing cash flows included in payments under finance lease obligations	1,964
Operating leases
Operating cash flows (fixed payments) included in other operating activities, net	5,092
Operating cash flows (liability reduction) included in other operating activities, net	$ 5,404

Leases - Balance Sheet Informat

Leases - Balance Sheet Information and Weighted-Average Lease Terms and Discount Rates Related to Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Finance lease right-of-use assets, net of accumulated depreciation	$ 9,326	$ 11,200	$ 0
Finance lease liabilities	9,520	11,200
Operating lease right-of-use assets	31,182	33,900
Operating lease liabilities	$ 32,354	$ 34,900
Weighted-average lease term
Finance leases	8 years 7 months 13 days
Operating leases	9 years 18 days
Weighted-average discount rate
Finance leases	3.01%
Operating leases	3.51%

Leases - Future Minimum Rental

Leases - Future Minimum Rental Commitments Under Finance and Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Leases [Abstract]
Finance leases, 2020	$ 1,970
Finance leases, 2021	1,615
Finance leases, 2022	1,556
Finance leases, 2023	871
Finance leases, 2024	572
Thereafter	4,451
Finance leases, total minimum lease payments	11,035
Finance leases, imputed interest	(1,515)
Finance lease liabilities	9,520	$ 11,200
Operating leases, 2020	4,916
Operating leases, 2021	4,576
Operating leases, 2022	4,101
Operating leases, 2023	4,064
Operating leases, 2024	3,968
Thereafter	16,349
Operating leases, total minimum lease payments	37,974
Operating leases, imputed interest	(5,620)
Operating lease liabilities	$ 32,354	$ 34,900

Deposits - Deposits Summary (De

Deposits - Deposits Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deposits [Abstract]
Noninterest-bearing demand	$ 2,891,215	$ 2,937,594
Interest-bearing demand	3,125,914	2,633,259
Savings	3,590,509	3,905,659
Time	1,637,919	1,887,899
Total deposits	$ 11,245,557	$ 11,364,411

Deposits - Interest Expense on

Deposits - Interest Expense on Deposits by Type (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest expense on deposits by type [Abstract]
Interest-bearing demand	$ 35,428	$ 18,479	$ 6,820
Savings	19,462	17,980	6,047
Time	24,281	17,477	9,850
Total	$ 79,171	$ 53,936	$ 22,717

Deposits - Additional Informati

Deposits - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deposits [Abstract]
Time deposits that exceed the FDIC insurance limit of $250 thousand	$ 285.7	$ 406.6

Deposits - Maturities of Intere

Deposits - Maturities of Interest-Bearing Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Maturities of interest-bearing deposits [Abstract]
2020	$ 1,359,100
2021	190,554
2022	50,364
2023	20,995
2024	14,316
Thereafter	2,590
Total time deposits	1,637,919	$ 1,887,899
Interest-bearing deposits with no stated maturity	6,716,423
Total interest-bearing deposits	$ 8,354,342	$ 8,426,817

Borrowings - Securities Sold Un

Borrowings - Securities Sold Under Repurchase Agreements - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Securities sold under repurchase agreements, secured by securities carrying amount	$ 105.6	$ 163.3

Borrowings - Schedule of Securi

Borrowings - Schedule of Securities Sold Under Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Securities sold under repurchase agreements by collateral pledged
Total securities sold under repurchase agreements	$ 53,572	$ 45,509
Other Residential Mortgage-Backed Securities Issued or Guaranteed by FNMA, FHLMC or GNMA [Member]
Securities sold under repurchase agreements by collateral pledged
Total securities sold under repurchase agreements	24,282	6,721
Commercial Mortgage-Backed Securities Issued or Guaranteed by FNMA, FHLMC or GNMA [Member]
Securities sold under repurchase agreements by collateral pledged
Total securities sold under repurchase agreements	$ 29,290	$ 38,788

Borrowings - Summary of Other B

Borrowings - Summary of Other Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
FHLB advances	$ 811		$ 879
Serviced GNMA loans eligible for repurchase	57,062		61,564
Finance lease liabilities	9,520	$ 11,200
Other	18,003		17,442
Total other borrowings	$ 85,396		$ 79,885

Borrowings - FHLB Advances - Ad

Borrowings - FHLB Advances - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019USD ($)Loan	Dec. 31, 2018USD ($)Loan	Dec. 31, 2017USD ($)
Long Term Borrowing [Member] | Federal Home Loan Bank Advances [Member] | BancTrust [Member] | Fair Market Value Adjustment [Member]
Debt Instrument [Line Items]
Long-term FHLB advances	$ 0	$ 0
Dallas [Member]
Debt Instrument [Line Items]
Additional debt instrument borrowing capacity	$ 3,178,000,000	$ 2,827,000,000
Dallas [Member] | Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Number of outstanding long-term FHLB advances | Loan	0	0
Dallas [Member] | Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Number of outstanding short-term FHLB advances | Loan	0
Atlanta and Dallas [Member]
Debt Instrument [Line Items]
Interest expense, short-term borrowings	$ 0	$ 4,400,000	$ 11,400,000
Atlanta and Dallas [Member] | Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Interest expense, long-term	$ 5,000	$ 6,000	$ 566,000
Atlanta [Member] | Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Number of outstanding long-term FHLB advances | Loan	2	2
Weighted-average cost related to FHLB advances (in hundredths)	0.64%	0.63%
Weighted average remaining maturity	2 years 4 months 13 days	3 years 4 months 28 days
Atlanta [Member] | Federal Home Loan Bank Advances [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate (in hundredths)	0.08%	0.08%
Atlanta [Member] | Federal Home Loan Bank Advances [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate (in hundredths)	0.75%	0.75%
Atlanta [Member] | Long Term Borrowing [Member] | Federal Home Loan Bank Advances [Member] | BancTrust [Member]
Debt Instrument [Line Items]
Long-term FHLB advances	$ 811,000	$ 879,000
Atlanta [Member] | Long Term Borrowing [Member] | Federal Home Loan Bank Advances [Member] | BancTrust [Member] | Minimum [Member]
Debt Instrument [Line Items]
Long-term FHLB advances	135,000	153,000
Atlanta [Member] | Long Term Borrowing [Member] | Federal Home Loan Bank Advances [Member] | BancTrust [Member] | Maximum [Member]
Debt Instrument [Line Items]
Long-term FHLB advances	$ 676,000	$ 726,000

Borrowings - Junior Subordinate

Borrowings - Junior Subordinated Debt Securities - Additional information (Details) $ in Thousands	Aug. 18, 2006USD ($)Quarter	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Variable Interest Entity [Line Items]
Junior subordinated debt securities		$ 61,856	$ 61,856
Total assets		13,497,877	13,286,460	$ 13,797,953
Total liabilities and shareholders' equity		13,497,877	13,286,460
Common securities		13,376	13,717
Net income		$ 150,460	149,584	105,630
Trustmark Preferred Capital Trust I [Member] | Junior Subordinated Debt Securities [Member]
Variable Interest Entity [Line Items]
Face amount of debt issued	$ 60,000
Maturity date	Sep. 30, 2036
Variable interest rate, description		three-month LIBOR
Basis spread over LIBOR rate (in hundredths)	1.72%
Junior subordinated debt securities	$ 61,900
Consecutive quarters that Trustmark may defer interest payments | Quarter	20
Total assets		$ 61,900	61,900
Total liabilities and shareholders' equity		61,900	61,900
Trust preferred securities		60,000	60,000
Common securities		1,900	1,900
Net income		79	74	55
Dividends paid		$ 79	$ 74	$ 55

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Summary of Noninterest Income Disaggregated by Reportable Operating Segment and Revenue Stream (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		$ 42,603	$ 43,702	[1]	$ 44,003	[1],[2]
Bank card and other fees		31,736	28,905	[1]	28,286	[1],[2]
Mortgage banking, net		29,822	34,674	[1]	29,902	[1],[2]
Insurance commissions		42,396	40,481	[1]	38,168	[1],[2]
Wealth management		30,679	30,338	[1]	30,340	[1],[2]
Other, net		9,809	6,736	[1]	13,949	[1],[2]
Security gains (losses), net		0	0		15	[1],[2]
Total Noninterest Income		187,045	184,836	[1]	184,663	[1],[2]
Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		42,603	43,702	[1]	44,003	[1],[2]
Bank card and other fees		28,030	27,008	[1]	28,036	[1],[2]
Insurance commissions		42,396	40,481	[1]	38,168	[1],[2]
Wealth management		30,679	30,338	[1]	30,340	[1],[2]
Other, net		9,866	6,836	[1]	6,597	[1],[2]
Total Noninterest Income		153,574	148,365	[1]	147,144	[1],[2]
Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees	[3]	3,706	1,897	[1]	250	[1],[2]
Mortgage banking, net	[3]	29,822	34,674	[1]	29,902	[1],[2]
Other, net	[3]	(57)	(100)	[1]	7,352	[1],[2]
Security gains (losses), net	[1],[2],[3]				15
Total Noninterest Income	[3]	33,471	36,471	[1]	37,519	[1],[2]
General Banking Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		42,509	43,614	[1]	43,928	[1],[2]
Bank card and other fees		31,678	28,801	[1]	28,208	[1],[2]
Mortgage banking, net		29,822	34,674	[1]	29,902	[1],[2]
Wealth management		379	296	[1]	210	[1],[2]
Other, net		9,367	6,545	[1]	13,781	[1],[2]
Security gains (losses), net	[1],[2]				15
Total Noninterest Income		113,755	113,930	[1]	116,044	[1],[2]
General Banking Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		42,509	43,614	[1]	43,928	[1],[2]
Bank card and other fees		27,972	26,904	[1]	27,958	[1],[2]
Wealth management		379	296	[1]	210	[1],[2]
Other, net		9,527	6,762	[1]	6,547	[1],[2]
Total Noninterest Income		80,387	77,576	[1]	78,643	[1],[2]
General Banking Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees	[3]	3,706	1,897	[1]	250	[1],[2]
Mortgage banking, net	[3]	29,822	34,674	[1]	29,902	[1],[2]
Other, net	[3]	(160)	(217)	[1]	7,234	[1],[2]
Security gains (losses), net	[1],[2],[3]				15
Total Noninterest Income	[3]	33,368	36,354	[1]	37,401	[1],[2]
Wealth Management Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		94	88	[1]	75	[1],[2]
Bank card and other fees		58	104	[1]	78	[1],[2]
Wealth management		30,300	30,042	[1]	30,130	[1],[2]
Other, net		409	186	[1]	138	[1],[2]
Total Noninterest Income		30,861	30,420	[1]	30,421	[1],[2]
Wealth Management Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		94	88	[1]	75	[1],[2]
Bank card and other fees		58	104	[1]	78	[1],[2]
Wealth management		30,300	30,042	[1]	30,130	[1],[2]
Other, net		306	69	[1]	20	[1],[2]
Total Noninterest Income		30,758	30,303	[1]	30,303	[1],[2]
Wealth Management Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Other, net	[3]	103	117	[1]	118	[1],[2]
Total Noninterest Income	[3]	103	117	[1]	118	[1],[2]
Insurance Segment [Member]
Revenue From Contract With Customer [Line Items]
Insurance commissions		42,396	40,481	[1]	38,168	[1],[2]
Other, net		33	5	[1]	30	[1],[2]
Total Noninterest Income		42,429	40,486	[1]	38,198	[1],[2]
Insurance Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Insurance commissions		42,396	40,481	[1]	38,168	[1],[2]
Other, net		33	5	[1]	30	[1],[2]
Total Noninterest Income		$ 42,429	$ 40,486	[1]	$ 38,198	[1],[2]
[1]	During the first quarter of 2019, Trustmark revised the composition of its operating segments by moving the Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes.  The prior period amounts presented include reclassifications to conform to the current period presentation.
[2]	Trustmark elected the modified retrospective approach of adoption; therefore, prior period balances are presented under legacy GAAP and may not be comparable to current year presentation.
[3]	Noninterest income not in scope for FASB ASC Topic 606 includes customer derivatives revenue and miscellaneous credit card income within bank card and other fees; mortgage banking, net; amortization of tax credits, accretion of the FDIC indemnification asset, cash surrender value on various life insurance policies, earnings on Trustmark’s non-qualified deferred compensation plans, other partnership investments and rental income within other, net; and securities gains (losses), net.

Income Taxes - Income Tax Provi

Income Taxes - Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current [Abstract]
Federal	$ 20,068	$ 4,532	$ 16,959
State	7,145	5,997	5,687
Deferred [Abstract]
Federal	(3,104)	9,392	7,280
State	(776)	2,348	1,820
Income tax provision excluding deferred tax asset revaluation and reversal of valuation allowance	23,333	22,269	31,746
Deferred tax expense (benefit) - re-measurement of deferred tax assets		0	25,619
Deferred tax expense (benefit) - reversal of valuation allowance		0	(8,650)
Income tax provision	$ 23,333	$ 22,269	$ 48,715

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Valuation allowance for deferred tax assets			$ 8.7
Decrease in valuation allowance resulting in income tax expense		$ (8.7)
Statutory income tax rate	21.00%	35.00%
Remeasurement result in decrease to net deferred tax asset		$ 25.6

Income Taxes - Income Tax Recon

Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of provision for tax from the federal rate to the effective tax rate [Abstract]
Income tax computed at statutory tax rate	$ 36,497	$ 36,089	$ 54,021
Tax exempt interest	(4,951)	(4,533)	(7,611)
Nondeductible interest expense	564	416	407
State income taxes, net	5,645	4,738	3,697
Income tax credits, net	(13,473)	(15,404)	(15,793)
Death benefit gains	(123)	(268)	(3,268)
Reversal of valuation allowance		0	(8,650)
Re-measurement of deferred tax assets		0	25,619
Other	(826)	1,231	293
Income tax provision	$ 23,333	$ 22,269	$ 48,715

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets [Abstract]
Loan purchase accounting	$ 845	$ 1,564
Other real estate	5,845	7,284
Allowance for loan losses	21,774	20,638
Deferred compensation	16,498	15,607
Financing and operating lease liabilities	10,469
Realized built-in losses	11,431	12,182
Securities	3,028	3,929
Pension and other postretirement benefit plans	5,194	4,108
Interest on nonaccrual loans	942	806
Unrealized losses on securities available for sale		10,679
Stock-based compensation	2,527	2,192
Federal carryovers		1,606
Other	8,790	9,179
Gross deferred tax asset	87,343	89,774
Deferred tax liabilities [Abstract]
Goodwill and other identifiable intangibles	15,336	16,229
Premises and equipment	11,913	12,109
Financing and operating lease right-of-use assets	10,127
Mortgage servicing rights	11,002	14,415
Securities	2,115	1,519
Other	5,192	5,600
Gross deferred tax liability	55,685	49,872
Net deferred tax asset	$ 31,658	$ 39,902

Income Taxes - Changes in Unrec

Income Taxes - Changes in Unrecognized Tax Benefits (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Changes in unrecognized tax benefits [Roll Forward]
Balance at beginning of period	$ 1,249
Change due to tax positions taken during the current year	279
Change due to tax positions taken during a prior year	134
Change due to the lapse of applicable statute of limitations during the current year	(138)
Change due to settlements with taxing authorities during the current year	0
Balance at end of period	1,524
Accrued interest, net of federal benefit, at end of period	271
Unrecognized tax benefits that would impact the effective tax rate, if recognized, at end of period	$ 1,218

Defined Benefit and Other Pos_3

Defined Benefit and Other Postretirement Benefits - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Recognized net loss due to defined benefit plan termination					$ 17,644
Trustmark Capital Accumulation Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Years of service required to vest			3 years
Defined benefit plan, additional asset contributions on termination basis	$ 17,600
Trustmark's minimum required contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions			$ 157
Trustmark's contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions			285
Trustmark Capital Accumulation Plan [Member] | Scenario Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Trustmark's minimum required contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions		$ 175
Trustmark Capital Accumulation Plan [Member] | Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, additional asset contributions on termination basis			387	$ 377
Recognized net loss due to defined benefit plan termination	$ 17,600		0	0	17,662
Estimated future benefit payments [Abstract]
Accumulated other comprehensive loss expected to be recognized during next fiscal year as components of net periodic benefit cost			(324)
Supplemental Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, additional asset contributions on termination basis			3,426	3,426
Estimated future benefit payments [Abstract]
Accumulated other comprehensive loss expected to be recognized during next fiscal year as components of net periodic benefit cost			(957)
Accumulated other comprehensive loss expected to be recognized during next fiscal year as prior service cost			149
Defined Contribution Plan [Member]
Other Benefit Plans - Defined Contribution Plan [Abstract]
Trustmarks contribution to defined contribution plan			$ 8,200	$ 7,900	$ 7,500
Contributions up to a maximum of eligible compensation			6.00%
Trustmark contributions to the plan			100.00%
Period when associates may become eligible to make elective deferral contributions after employment			30 days
Eligible associates must complete number of years of service			1 year

Defined Benefit and Other Pos_4

Defined Benefit and Other Postretirement Benefits - Plan Benefit Obligation, Plan Assets and Funded Status of the Plan (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Trustmark Capital Accumulation Plan [Member]
Change in plan assets [ Roll Forward]
Employer contributions	$ 17,600
Trustmark Capital Accumulation Plan [Member] | Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member]
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year		$ 9,179	$ 10,102
Service cost		211	277	$ 253
Interest cost		361	332	1,461
Actuarial (gain) loss		875	(827)
Benefits paid		(1,566)	(705)
Benefit obligation, end of year		9,060	9,179	10,102
Change in plan assets [ Roll Forward]
Fair value of plan assets, beginning of year		3,954	4,596
Actual return on plan assets		668	(314)
Employer contributions		387	377
Benefit payments		(1,566)	(705)
Fair value of plan assets, end of year		3,443	3,954	4,596
Funded status at end of year - net liability		(5,617)	(5,225)
Amounts recognized in accumulated other comprehensive income (loss) [Abstract]
Net loss		1,893	2,170
Supplemental Retirement Plan [Member]
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year		53,257	57,930
Service cost		109	116	141
Interest cost		2,044	1,865	2,103
Actuarial (gain) loss		5,498	(3,228)
Benefits paid		(3,426)	(3,426)
Benefit obligation, end of year		57,482	53,257	57,930
Change in plan assets [ Roll Forward]
Fair value of plan assets, beginning of year		0	0
Employer contributions		3,426	3,426
Benefit payments		(3,426)	(3,426)
Fair value of plan assets, end of year		0	0	$ 0
Funded status at end of year - net liability		(57,482)	(53,257)
Amounts recognized in accumulated other comprehensive income (loss) [Abstract]
Net loss		18,275	13,403
Prior service cost		609	859
Amounts recognized		$ 18,884	$ 14,262

Defined Benefit and Other Pos_5

Defined Benefit and Other Postretirement Benefits - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net periodic benefit cost [Abstract]
Recognized net loss due to defined benefit plan termination				$ 17,644
Trustmark Capital Accumulation Plan [Member] | Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member]
Net periodic benefit cost [Abstract]
Service cost		$ 211	$ 277	253
Interest cost		361	332	1,461
Expected return on plan assets		(202)	(227)	(317)
Recognized net loss due to defined benefit plan termination	$ 17,600	0	0	17,662
Recognized net loss due to lump sum settlements		312	161	0
Recognized net actuarial loss		373	571	1,414
Net periodic benefit cost		1,055	1,114	20,473
Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes:
Net (gain) loss - Total recognized in other comprehensive income (loss)		(277)	(1,017)	(18,168)
Total recognized in net periodic benefit cost and other comprehensive income (loss)		$ 778	$ 97	$ 2,305
Weighted-average assumptions as of end of year [Abstract]
Discount rate for benefit obligation (in hundredths)		2.84%	3.97%	3.32%
Discount rate for net periodic benefit cost (in hundredths)		3.97%	3.32%	3.71%
Expected long-term return on plan assets (in hundredths)		5.00%	5.00%	5.00%
Supplemental Retirement Plan [Member]
Net periodic benefit cost [Abstract]
Service cost		$ 109	$ 116	$ 141
Interest cost		2,044	1,865	2,103
Amortization of prior service credits		250	250	250
Recognized net actuarial loss		627	884	866
Net periodic benefit cost		3,030	3,115	3,360
Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes:
Net loss (gain)		4,872	(4,111)	(224)
Amortization of prior service cost		(250)	(250)	(250)
Net (gain) loss - Total recognized in other comprehensive income (loss)		4,622	(4,361)	(474)
Total recognized in net periodic benefit cost and other comprehensive income (loss)		$ 7,652	$ (1,246)	$ 2,886
Weighted-average assumptions as of end of year [Abstract]
Discount rate for benefit obligation (in hundredths)		2.84%	3.97%	3.32%
Discount rate for net periodic benefit cost (in hundredths)		3.97%	3.32%	3.71%

Defined Benefit and Other Pos_6

Defined Benefit and Other Postretirement Benefits - Weighted-Average Asset Allocation (Details) - Trustmark Capital Accumulation Plan [Member] - Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member]	Dec. 31, 2019	Dec. 31, 2018
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	100.00%	100.00%
Money Market Funds [Member]
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	2.00%	8.00%
Exchange Traded Equity Securities Funds [Member]
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	46.00%	52.00%
Exchange Traded Fixed Income Funds [Member]
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	41.00%	29.00%
International Exchange Traded Funds [Member]
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	11.00%	11.00%

Defined Benefit and Other Pos_7

Defined Benefit and Other Postretirement Benefits - Plan Assets Measured at Fair Value (Details) - Trustmark Capital Accumulation Plan [Member] - Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Asset target allocations [Abstract]
Fair value of plan assets	$ 3,443	$ 3,954	$ 4,596
Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	3,443	3,954
Level 2 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
Level 3 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
Money Market Funds [Member]
Asset target allocations [Abstract]
Fair value of plan assets	51	304
Money Market Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	51	304
Money Market Funds [Member] | Level 2 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
Money Market Funds [Member] | Level 3 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
Exchange Traded Equity Securities Funds [Member]
Asset target allocations [Abstract]
Fair value of plan assets	1,592	2,044
Exchange Traded Equity Securities Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	1,592	2,044
Exchange Traded Equity Securities Funds [Member] | Level 2 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
Exchange Traded Equity Securities Funds [Member] | Level 3 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
International Exchange Traded Funds [Member]
Asset target allocations [Abstract]
Fair value of plan assets	383	444
International Exchange Traded Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	383	444
International Exchange Traded Funds [Member] | Level 2 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
International Exchange Traded Funds [Member] | Level 3 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
Exchange Traded Fixed Income Funds [Member]
Asset target allocations [Abstract]
Fair value of plan assets	1,417	1,162
Exchange Traded Fixed Income Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	1,417	1,162
Exchange Traded Fixed Income Funds [Member] | Level 2 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
Exchange Traded Fixed Income Funds [Member] | Level 3 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	$ 0	$ 0

Defined Benefit and Other Pos_8

Defined Benefit and Other Postretirement Benefits - Estimated Future Benefit Payments and Other Disclosures (Details) $ in Thousands	Dec. 31, 2019USD ($)
Supplemental Retirement Plan [Member]
Estimated future benefit payments [Abstract]
2020	$ 3,963
2021	4,051
2022	4,284
2023	4,124
2024	4,144
2025 - 2029	17,840
Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member] | Trustmark Capital Accumulation Plan [Member]
Estimated future benefit payments [Abstract]
2020	1,147
2021	1,056
2022	873
2023	1,220
2024	997
2025 - 2029	$ 2,443

Stock and Incentive Compensat_3

Stock and Incentive Compensation Plans - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019shares
Performance Based Award [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Return on average tangible equity, performance measure	100.00%
Total shareholder return, performance measure	100.00%
Time-Vested Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years
Stock and Incentive Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock available for issuance (in shares)	909,818

Stock and Incentive Compensat_4

Stock and Incentive Compensation Plans - Summary of Stock Plan Activity (Details) - Stock and Incentive Compensation Plan [Member] - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Performance Based Award [Member]
Shares [Roll Forward]
Nonvested shares, beginning of year (in shares)	177,695	213,516	237,136
Granted (in shares)	50,862	51,174	58,406
Released from restriction (in shares)	(61,347)	(55,351)	(67,279)
Forfeited (in shares)	(17,296)	(31,644)	(14,747)
Nonvested shares, end of year (in shares)	149,914	177,695	213,516
Weighted-Average Grant Date Fair Value [Abstract]
Nonvested shares, beginning of year (in dollars per share)	$ 27.10	$ 25.37	$ 26.27
Granted (in dollars per share)	33.44	31.88	33.31
Released from restriction (in dollars per share)	20.18	25.32	34.78
Forfeited (in dollars per share)	20.18	26.26	28.42
Nonvested shares, end of year (in dollars per share)	$ 32.88	$ 27.10	$ 25.37
Time-Vested Awards [Member]
Shares [Roll Forward]
Nonvested shares, beginning of year (in shares)	321,870	320,357	322,056
Granted (in shares)	113,673	118,325	105,524
Released from restriction (in shares)	(124,598)	(107,180)	(101,289)
Forfeited (in shares)	(10,939)	(9,632)	(5,934)
Nonvested shares, end of year (in shares)	300,006	321,870	320,357
Weighted-Average Grant Date Fair Value [Abstract]
Nonvested shares, beginning of year (in dollars per share)	$ 28.48	$ 25.40	$ 22.65
Granted (in dollars per share)	33.42	31.96	33.79
Released from restriction (in dollars per share)	21.64	23.02	25.35
Forfeited (in dollars per share)	32.73	29.30	26.52
Nonvested shares, end of year (in dollars per share)	$ 33.04	$ 28.48	$ 25.40

Stock and Incentive Compensat_5

Stock and Incentive Compensation Plans - Compensation Expense for Awards Under Stock Plan (Details) - Stock and Incentive Compensation Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Compensation expense [Abstract]
Recognized compensation expense	$ 4,787	$ 3,870	$ 4,309
Unrecognized compensation expense	5,640
Performance Based Award [Member]
Compensation expense [Abstract]
Recognized compensation expense	1,524	861	1,387
Unrecognized compensation expense	$ 1,914
Weighted average life of unrecognized compensation expense	1 year 7 months 2 days
Time-Vested Awards [Member]
Compensation expense [Abstract]
Recognized compensation expense	$ 3,263	$ 3,009	$ 2,922
Unrecognized compensation expense	$ 3,726
Weighted average life of unrecognized compensation expense	1 year 8 months 23 days

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Unused commitments to extend credit	$ 4,349	$ 3,918
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Potential exposure to credit loss in the event of nonperformance	$ 105.2	100.2
Letters of credit, maturity term - maximum	3 years
Collateral held, fair value	$ 26.3	$ 29.8

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Apr. 01, 2020	Apr. 01, 2019	Mar. 11, 2016
Stockholders Equity [Line items]
Capital conservation buffer rate	2.50%	1.875%
Dividend potential for next fiscal year	$ 56.8
Period for which retained net income considered for approval	2 years
Stock Repurchase Program 1 [Member] | Common Stock [Member]
Stockholders Equity [Line items]
Amount of stock authorized for repurchase						$ 100
Repurchase shares of common stock	1,200,000	2,000,000	0
Repurchase shares of common stock, value	$ 36.9	$ 62.4
2016 Program [Member]
Stockholders Equity [Line items]
Repurchase shares of common stock	3,200,000
Repurchase shares of common stock, value	$ 100
Stock Repurchase Program 2 [Member]
Stockholders Equity [Line items]
Amount of stock authorized for repurchase					$ 100
Stock Repurchase Program 2 [Member] | Common Stock [Member]
Stockholders Equity [Line items]
Repurchase shares of common stock	601,000
Repurchase shares of common stock, value	$ 19.7
Stock Repurchase Program | Common Stock [Member]
Stockholders Equity [Line items]
Repurchase shares of common stock	1,800,000
Repurchase shares of common stock, value	$ 56.6
Stock Repurchase Program 3 [Member] | Scenario Forecast [Member]
Stockholders Equity [Line items]
Amount of stock authorized for repurchase				$ 100

Shareholders' Equity - Table of

Shareholders' Equity - Table of Actual Regulatory Capital Amounts and Ratios (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Trustmark Corporation [Member] | Common Equity Tier 1 Capital (to Risk Weighted Assets) [Member]
Common Equity Tier One Risk Based Capital [Abstract]
Actual Regulatory Capital Amount		$ 1,312,668	$ 1,271,538
Actual Regulatory Capital Ratio		11.93%	11.77%
Minimum Regulatory Capital Required Ratio		7.00%	6.375%
Minimum Regulatory Provision to be Well-Capitalized Ratio	[1]
Trustmark Corporation [Member] | Tier 1 Capital (to Risk Weighted Assets) [Member]
Tier 1 Capital (to Risk Weighted Assets) [Abstract]
Actual Regulatory Capital Amount		$ 1,372,668	$ 1,331,538
Actual Regulatory Capital Ratio		12.48%	12.33%
Minimum Regulatory Capital Required Ratio		8.50%	7.875%
Minimum Regulatory Provision to be Well-Capitalized Ratio	[1]
Trustmark Corporation [Member] | Total Capital (to Risk Weighted Assets) [Member]
Total Capital (to Risk Weighted Assets) [Abstract]
Actual Regulatory Capital Amount		$ 1,457,760	$ 1,412,059
Actual Regulatory Capital Ratio		13.25%	13.07%
Minimum Regulatory Capital Required Ratio		10.50%	9.875%
Minimum Regulatory Provision to be Well-Capitalized Ratio	[1]
Trustmark Corporation [Member] | Tier 1 Leverage (to Average Assets) [Member]
Tier 1 Leverage (to Average Assets) [Abstract]
Actual Regulatory Capital Amount		$ 1,372,668	$ 1,331,538
Actual Regulatory Capital Ratio		10.48%	10.26%
Minimum Regulatory Capital Required Ratio		4.00%	4.00%
Minimum Regulatory Provision to be Well-Capitalized Ratio	[1]
Trustmark National Bank [Member] | Common Equity Tier 1 Capital (to Risk Weighted Assets) [Member]
Common Equity Tier One Risk Based Capital [Abstract]
Actual Regulatory Capital Amount		$ 1,352,893	$ 1,311,548
Actual Regulatory Capital Ratio		12.30%	12.14%
Minimum Regulatory Capital Required Ratio		7.00%	6.375%
Minimum Regulatory Provision to be Well-Capitalized Ratio		6.50%	6.50%
Trustmark National Bank [Member] | Tier 1 Capital (to Risk Weighted Assets) [Member]
Tier 1 Capital (to Risk Weighted Assets) [Abstract]
Actual Regulatory Capital Amount		$ 1,352,893	$ 1,311,548
Actual Regulatory Capital Ratio		12.30%	12.14%
Minimum Regulatory Capital Required Ratio		8.50%	7.875%
Minimum Regulatory Provision to be Well-Capitalized Ratio		8.00%	8.00%
Trustmark National Bank [Member] | Total Capital (to Risk Weighted Assets) [Member]
Total Capital (to Risk Weighted Assets) [Abstract]
Actual Regulatory Capital Amount		$ 1,437,985	$ 1,392,069
Actual Regulatory Capital Ratio		13.07%	12.89%
Minimum Regulatory Capital Required Ratio		10.50%	9.875%
Minimum Regulatory Provision to be Well-Capitalized Ratio		10.00%	10.00%
Trustmark National Bank [Member] | Tier 1 Leverage (to Average Assets) [Member]
Tier 1 Leverage (to Average Assets) [Abstract]
Actual Regulatory Capital Amount		$ 1,352,893	$ 1,311,548
Actual Regulatory Capital Ratio		10.35%	10.13%
Minimum Regulatory Capital Required Ratio		4.00%	4.00%
Minimum Regulatory Provision to be Well-Capitalized Ratio		5.00%	5.00%
[1]	n/a

Shareholders' Equity - Net Chan

Shareholders' Equity - Net Change in Components of Accumulated Other Comprehensive Income (Loss) and the Related Tax Effects (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax amount	$ 42,772	$ (9,907)	$ 9,835
Other comprehensive income (loss), tax (expense) benefit	(10,693)	2,477	(3,762)
Other comprehensive income (loss), before reclassifications, net of tax amount	31,420	(8,416)	(6,364)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	659	986	12,437
Other comprehensive income (loss), net of tax amount	32,079	(7,430)	6,073
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	44,136	(19,221)	(13,994)
Reclassification from accumulated other comprehensive income, current period, before tax amount			(15)
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, before tax amount	3,605	3,761	4,721
Other comprehensive income (loss), before tax amount	47,741	(15,460)	(9,288)
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	(11,033)	4,805	5,353
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit			6
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, tax (expense) benefit	(901)	(940)	(1,806)
Other comprehensive income (loss), tax (expense) benefit	(11,934)	3,865	3,553
Other comprehensive income (loss), before reclassifications, net of tax amount	33,103	(14,416)	(8,641)
Reclassification from accumulated other comprehensive income, current period, net of tax amount			(9)
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, net of tax amount	2,704	2,821	2,915
Other comprehensive income (loss), net of tax amount	35,807	(11,595)	(5,735)
Change in Net Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(5,703)	3,742	(1,231)
Reclassification from accumulated other comprehensive income, current period, before tax amount	796	1,225	1,962
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	1,425	(936)	471
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(199)	(306)	(751)
Other comprehensive income (loss), before reclassifications, net of tax amount	(4,278)	2,806	(760)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	597	919	1,211
Net Change in Prior Service Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	250	250	250
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(63)	(63)	(96)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	187	187	154
Recognized Net Loss Due to Lump Sum Settlements [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	312	161
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(77)	(39)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	235	122
Pension and Other Postretirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	(4,345)	5,378	18,643
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	1,086	(1,344)	(7,131)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	(3,259)	4,034	11,512
Cash Flow Hedge Derivatives {Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(145)	497	198
Reclassification from accumulated other comprehensive income, current period, before tax amount	(479)	(322)	282
Other comprehensive income (loss), before tax amount	(624)	175	480
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	36	(124)	(76)
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	119	80	(108)
Other comprehensive income (loss), tax (expense) benefit	155	(44)	(184)
Other comprehensive income (loss), before reclassifications, net of tax amount	(109)	373	122
Reclassification from accumulated other comprehensive income, current period, net of tax amount	(360)	(242)	174
Other comprehensive income (loss), net of tax amount	$ (469)	$ 131	296
Recognized Net Loss Due to Defined Benefit Plan Termination [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount			17,662
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit			(6,755)
Reclassification from accumulated other comprehensive income, current period, net of tax amount			$ 10,907

Shareholders' Equity - Changes

Shareholders' Equity - Changes in Balances of Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 1,591,453	$ 1,571,701	$ 1,520,208
Other comprehensive income (loss) before reclassification	31,420	(8,416)	(6,364)
Amounts reclassified from accumulated other comprehensive loss	659	986	12,437
Other comprehensive income (loss), net of tax amount	32,079	(7,430)	6,073
Reclassification of certain income tax effects related to the changein the federal statutory income tax rate under the Tax Reform Act		(8,524)
Balance	1,660,702	1,591,453	1,571,701
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(43,824)	(26,535)	(20,800)
Other comprehensive income (loss) before reclassification	35,807	(11,595)	(5,726)
Amounts reclassified from accumulated other comprehensive loss			(9)
Other comprehensive income (loss), net of tax amount	35,807	(11,595)	(5,735)
Reclassification of certain income tax effects related to the changein the federal statutory income tax rate under the Tax Reform Act		(5,694)
Balance	(8,017)	(43,824)	(26,535)
Defined Benefit Pension Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(12,324)	(13,468)	(24,980)
Other comprehensive income (loss) before reclassification	(4,278)	2,806	(760)
Amounts reclassified from accumulated other comprehensive loss	1,019	1,228	12,272
Other comprehensive income (loss), net of tax amount	(3,259)	4,034	11,512
Reclassification of certain income tax effects related to the changein the federal statutory income tax rate under the Tax Reform Act		(2,890)
Balance	(15,583)	(12,324)	(13,468)
Cash Flow Hedge Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	469	278	(18)
Other comprehensive income (loss) before reclassification	(109)	373	122
Amounts reclassified from accumulated other comprehensive loss	(360)	(242)	174
Other comprehensive income (loss), net of tax amount	(469)	131	296
Reclassification of certain income tax effects related to the changein the federal statutory income tax rate under the Tax Reform Act		60
Balance		469	278
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(55,679)	(39,725)	(45,798)
Balance	$ (23,600)	$ (55,679)	$ (39,725)

Fair Value - Financial Assets a

Fair Value - Financial Assets and Liabilities Measured at Fair Value Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 1,602,404	$ 1,811,813
Loans held for sale	226,347	153,799
Mortgage servicing rights	79,394	95,596	$ 84,269
U.S. Government Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	22,327	30,335
Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	25,465	50,676
Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,602,404	1,811,813
Loans held for sale	226,347	153,799
Mortgage servicing rights	79,394	95,596
Other assets - derivatives	17,956	12,347
Other liabilities - derivatives	6,063	4,213
Recurring Basis [Member] | U.S. Government Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	22,327	30,335
Recurring Basis [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	25,465	50,676
Recurring Basis [Member] | Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,554,612	1,730,802
Level 1 [Member] | Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Loans held for sale	0	0
Mortgage servicing rights	0	0
Other assets - derivatives	244	5,006
Other liabilities - derivatives	4,414	66
Level 1 [Member] | Recurring Basis [Member] | U.S. Government Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Level 1 [Member] | Recurring Basis [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Level 1 [Member] | Recurring Basis [Member] | Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Level 2 [Member] | Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,602,404	1,811,813
Loans held for sale	226,347	153,799
Mortgage servicing rights	0	0
Other assets - derivatives	16,273	6,154
Other liabilities - derivatives	1,649	4,147
Level 2 [Member] | Recurring Basis [Member] | U.S. Government Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	22,327	30,335
Level 2 [Member] | Recurring Basis [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	25,465	50,676
Level 2 [Member] | Recurring Basis [Member] | Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,554,612	1,730,802
Level 3 [Member] | Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Loans held for sale	0	0
Mortgage servicing rights	79,394	95,596
Other assets - derivatives	1,439	1,187
Other liabilities - derivatives	0	0
Level 3 [Member] | Recurring Basis [Member] | U.S. Government Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Level 3 [Member] | Recurring Basis [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Level 3 [Member] | Recurring Basis [Member] | Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 0	$ 0

Fair Value - Changes in Level 3

Fair Value - Changes in Level 3 Assets Measured at Fair Value on a Recurring Basis (Details) - Recurring Basis [Member] - Level 3 [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
MSR [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		$ 95,596	$ 84,269
Total net (loss) gain included in Mortgage banking, net	[1]	(32,913)	(4,432)
Additions		16,711	15,759
Sales		0	0
Ending Balance		79,394	95,596
The amount of total gains (losses) for the period included in earnings that are attributable to the change in unrealized gains or losses still held, end of period		(21,078)	7,342
Other Assets - Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		1,187	900
Total net (loss) gain included in Mortgage banking, net	[1]	6,775	4,390
Additions		0	0
Sales		(6,523)	(4,103)
Ending Balance		1,439	1,187
The amount of total gains (losses) for the period included in earnings that are attributable to the change in unrealized gains or losses still held, end of period		$ 1,284	$ 636
[1]	Total net (loss) gain included in Mortgage banking, net relating to the MSR includes changes in fair value due to market changes and due to run-off.

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Outstanding balances in impaired loans	$ 41,200	$ 55,800
Impaired loans, related allowance	5,500	6,400
Foreclosed assets re-measured after initial recognition	15,000	19,200
Write-downs of allowance for foreclosed assets after initial recognition	2,400	873
Noninterest gain (loss) Mortgage banking, net for changes in fair value of LHFS	1,500	1,400	$ 3,000
Interest earned on LHFS included in Interest and fees on LHFS and LHFI	5,900	4,900	$ 4,900
GNMA optional repurchase loans	$ 57,062	$ 61,564

Fair Value - Carrying Amounts a

Fair Value - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	$ 738,099	$ 909,643
Net LHFI	9,251,351	8,756,578
Acquired loans	71,786	105,701
Deposits	11,245,557	11,364,411
Federal funds purchased and securities sold under repurchase agreements	256,020	50,471
Other borrowings	85,396	79,885
Junior subordinated debt securities	61,856	61,856
Level 2 [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and short-term investments	358,916	350,391
Securities held to maturity	738,099	909,643
Deposits	11,245,557	11,364,411
Federal funds purchased and securities sold under repurchase agreements	256,020	50,471
Other borrowings	85,396	79,885
Junior subordinated debt securities	61,856	61,856
Level 2 [Member] | Estimate Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and short-term investments	358,916	350,391
Securities held to maturity	746,202	889,733
Deposits	11,250,071	11,365,203
Federal funds purchased and securities sold under repurchase agreements	256,020	50,471
Other borrowings	85,374	79,827
Junior subordinated debt securities	50,722	53,196
Level 3 [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI	9,251,351	8,756,578
Acquired loans	71,786	105,701
Level 3 [Member] | Estimate Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI	9,235,674	8,757,817
Acquired loans	$ 71,786	$ 105,701

Fair Value - Fair Value and the

Fair Value - Fair Value and the Contractual Principal Outstanding of the LHFS (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair value and the contractual principal outstanding of the LHFS [Abstract]
Fair value of LHFS	$ 169,285	$ 92,235
LHFS contractual principal outstanding	164,420	89,056
Fair value less unpaid principal	$ 4,865	$ 3,179

Derivative Financial Instrume_3

Derivative Financial Instruments - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019USD ($)Contract	Dec. 31, 2018USD ($)Contract	Dec. 31, 2017USD ($)	Apr. 04, 2013USD ($)
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Period for which cash flow hedges will be used to hedge quarterly interest payments	5 years
Derivative inception date	Dec. 31, 2014
Derivative maturity date	Dec. 31, 2019
Description of variable rate basis for derivative	three-month LIBOR
Ineffectiveness related to interest rate swap designated as a cash flow hedge	$ 0	$ 0	$ 0
Accumulated net, after tax gain included in accumulated other comprehensive loss	$ 0	$ 469,000
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Junior Subordinated Debentures [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total notional amount				$ 60,000,000
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Three-month LIBOR [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Swap fixed interest rate to be paid	1.66%
Derivatives not Designated as Hedging Instruments [Member] | Beneficiary [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Number of risk participation agreements | Contract	3	3
Aggregate notional amount of credit risk participation agreements	$ 37,600,000	$ 23,100,000
Derivatives not Designated as Hedging Instruments [Member] | Guarantor [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Number of risk participation agreements | Contract	10	7
Aggregate notional amount of credit risk participation agreements	$ 79,300,000	$ 39,000,000
Derivatives not Designated as Hedging Instruments [Member] | Mortgage Servicing Rights Hedge [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total notional amount	564,000,000	318,000,000
Net (negative) positive ineffectiveness on MSR fair value	(11,500,000)	2,400,000	$ 254,000
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Swap [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total notional amount	893,100,000	475,800,000
Termination value of derivatives	1,000,000	75,000
Collateral Posted	1,400,000
Derivatives not Designated as Hedging Instruments [Member] | Forward Contracts [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet obligations	209,000,000	132,000,000
Valuation adjustment	(486,000)	(1,800,000)
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Lock Commitments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet obligations	92,100,000	71,200,000
Valuation adjustment	$ 1,400,000	$ 1,200,000

Derivative Financial Instrume_4

Derivative Financial Instruments - Fair Value of Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	$ 16,209	$ 6,112
Fair value of derivative liability	1,122	2,369
Derivatives in Hedging Relationships [Member] | Interest Rate Swap [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset		625
Derivatives not Designated as Hedging Instruments [Member] | Future Contracts [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset		4,445
Derivatives not Designated as Hedging Instruments [Member] | Future Contracts [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	2,654
Derivatives not Designated as Hedging Instruments [Member] | Credit Risk Participation Agreement [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	64	42
Derivatives not Designated as Hedging Instruments [Member] | Credit Risk Participation Agreement [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	41	5
Derivatives not Designated as Hedging Instruments [Member] | Forward Contracts [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	486	1,773
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Swap [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	16,209	5,487
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Swap [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	1,122	2,369
Derivatives not Designated as Hedging Instruments [Member] | Exchange Traded Purchased Options [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	244	561
Derivatives not Designated as Hedging Instruments [Member] | OTC Written Options (Rate Locks) [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	1,439	1,187
Derivatives not Designated as Hedging Instruments [Member] | Exchange Traded Written Options [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	$ 1,760	$ 66

Derivative Financial Instrume_5

Derivative Financial Instruments - Effects of Derivative Instruments on Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivatives in Hedging Relationships [Member] | Accumulated Other Comprehensive Loss and Other Interest Expense [Member]
Derivatives, Fair Value [Line Items]
Amount of gain (loss) reclassified from accumulated other comprehensive loss and recognized in other interest expense	$ 479	$ 322	$ (282)
Derivatives not Designated as Hedging Instruments [Member] | Mortgage Banking, Net [Member]
Derivatives, Fair Value [Line Items]
Amount of gain (loss) recognized in mortgage banking, net	11,096	(6,191)	(1,873)
Derivatives not Designated as Hedging Instruments [Member] | Bank Card and Other Fees [Member]
Derivatives, Fair Value [Line Items]
Amount of gain (loss) recognized in bank card and other fees	$ (776)	$ (357)	$ (31)

Derivative Financial Instrume_6

Derivative Financial Instruments - Schedule of Amount Included in Other Comprehensive Income (Loss) for Derivative Instruments Designated as Hedges of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss), net of tax	$ (109)	$ 373	$ 122
Derivatives in Hedging Relationships [Member]
Derivatives, Fair Value [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss), net of tax	$ (109)	$ 373	$ 122

Derivative Financial Instrume_7

Derivative Financial Instruments - Information about Financial Instruments that are Eligible for Offset in the Consolidated Balance Sheets (Details) - Interest Rate Swap [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Offsetting Derivative Assets
Gross Amounts of Recognized Assets, Offsetting of Derivative Assets	$ 16,209	$ 6,112
Gross Amounts Offset in the Statement of Financial Position, Offsetting of Derivative Assets	0	0
Net Amounts of Assets presented in the Statement of Financial Position, Offsetting of Derivative Assets	16,209	6,112
Financial Instruments, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Assets	0	(339)
Cash Collateral Received, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Assets	0	(620)
Net Amount, Offsetting of Derivative Assets	16,209	5,153
Offsetting Derivative Liabilities
Gross Amounts of Recognized Liabilities, Offsetting of Derivative Liabilities	1,122	2,369
Gross Amounts Offset in the Statement of Financial Position, Offsetting of Derivative Liabilities	0	0
Net Amounts of Liabilities presented in the Statement of Financial Position, Offsetting of Derivative Liabilities	1,122	2,369
Financial Instruments, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Liabilities	0	(339)
Cash Collateral Posted, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Liabilities	(1,390)	0
Net Amount, Offsetting of Derivative Liabilities	$ (268)	$ 2,030

Segment Information - Additiona

Segment Information - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019Segment
Segment Reporting [Abstract]
Number of segments in which the business operates	3

Segment Information - Schedule

Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Segment Reporting Information [Line Items]
Net interest income	$ 426,589	$ 419,420		$ 407,550
Provision for loan losses, net	10,839	16,988		7,699
Noninterest income	187,045	184,836	[1]	184,663	[1],[2]
Noninterest expense	429,002	415,415		430,169
Income Before Income Taxes	173,793	171,853		154,345
Income taxes	23,333	22,269		48,715
Net Income	150,460	149,584		105,630
Selected Financial Information
Total assets	13,497,877	13,286,460		13,797,953
Depreciation and amortization	39,420	38,940		38,471
General Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	422,661	415,561		402,507
Provision for loan losses, net	10,838	17,001		7,485
Noninterest income	113,755	113,930	[1]	116,044	[1],[2]
Noninterest expense	370,493	355,389		370,793
Income Before Income Taxes	155,085	157,101		140,273
Income taxes	18,721	18,560		43,427
Net Income	136,364	138,541		96,846
Selected Financial Information
Total assets	13,333,518	13,111,362		13,627,012
Depreciation and amortization	38,637	38,182		37,704
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest income	3,686	3,633		4,809
Provision for loan losses, net	1	(13)		214
Noninterest income	30,861	30,420	[1]	30,421	[1],[2]
Noninterest expense	26,365	29,170		29,989
Income Before Income Taxes	8,181	4,896		5,027
Income taxes	2,040	1,225		1,923
Net Income	6,141	3,671		3,104
Selected Financial Information
Total assets	90,113	106,179		102,773
Depreciation and amortization	267	186		137
Insurance [Member]
Segment Reporting Information [Line Items]
Net interest income	242	226		234
Noninterest income	42,429	40,486	[1]	38,198	[1],[2]
Noninterest expense	32,144	30,856		29,387
Income Before Income Taxes	10,527	9,856		9,045
Income taxes	2,572	2,484		3,365
Net Income	7,955	7,372		5,680
Selected Financial Information
Total assets	74,246	68,919		68,168
Depreciation and amortization	$ 516	$ 572		$ 630
[1]	During the first quarter of 2019, Trustmark revised the composition of its operating segments by moving the Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes.  The prior period amounts presented include reclassifications to conform to the current period presentation.
[2]	Trustmark elected the modified retrospective approach of adoption; therefore, prior period balances are presented under legacy GAAP and may not be comparable to current year presentation.

Parent Company Only Financial_3

Parent Company Only Financial Information - Parent Only Financial Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Other assets	$ 532,389	$ 498,864
Total Assets	13,497,877	13,286,460	$ 13,797,953
Liabilities and Shareholders' Equity:
Junior subordinated debt securities	61,856	61,856
Shareholders' equity	1,660,702	1,591,453	1,571,701	$ 1,520,208
Total Liabilities and Shareholders' Equity	13,497,877	13,286,460
Expense:
Net Income	150,460	149,584	105,630
Operating Activities
Net income	150,460	149,584	105,630
Adjustments to reconcile net income to net cash provided by operating activities:
Other	23,838	(6,886)	2,121
Net cash from operating activities	116,447	239,198	206,607
Investing Activities
Net cash from investing activities	(74,239)	438,787	(348,862)
Financing Activities
Common stock dividends	(59,804)	(62,425)	(62,795)
Repurchase and retirement of common stock	(56,615)	(62,421)	0
Net cash from financing activities	(32,853)	(664,192)	150,317
Trustmark Corp (Parent Company Only) [Member]
Assets
Investment in banks	1,707,644	1,637,338
Other assets	15,778	16,975
Total Assets	1,723,422	1,654,313
Liabilities and Shareholders' Equity:
Accrued expense	864	1,004
Junior subordinated debt securities	61,856	61,856
Shareholders' equity	1,660,702	1,591,453
Total Liabilities and Shareholders' Equity	1,723,422	1,654,313
Revenue:
Dividends received from banks	120,297	128,592	65,663
Earnings of subsidiaries over distributions	32,971	23,791	42,211
Other income	90	86	71
Total Revenue	153,358	152,469	107,945
Expense:
Other expense	2,898	2,885	2,315
Total Expense	2,898	2,885	2,315
Net Income	150,460	149,584	105,630
Operating Activities
Net income	150,460	149,584	105,630
Adjustments to reconcile net income to net cash provided by operating activities:
Net change in investment in subsidiaries	(32,971)	(23,791)	(42,211)
Other	(1,800)	(1,395)	(1,697)
Net cash from operating activities	115,689	124,398	61,722
Investing Activities
Payment for investments in subsidiaries	0	0	(30,755)
Repayment for investments in subsidiaries			32,000
Net cash from investing activities	0	0	1,245
Financing Activities
Common stock dividends	(59,804)	(62,425)	(62,795)
Repurchase and retirement of common stock	(56,615)	(62,421)
Net cash from financing activities	(116,419)	(124,846)	(62,795)
Net change in cash and cash equivalents	(730)	(448)	172
Cash and cash equivalents at beginning of year	16,437	16,885	16,713
Cash and cash equivalents at end of year	$ 15,707	$ 16,437	$ 16,885

Parent Company Only Financial_4

Parent Company Only Financial Information - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements Captions [Line Items]
Income taxes paid	$ 24,809	$ 12,435	$ 7,371
Trustmark Corp (Parent Company Only) [Member]
Condensed Financial Statements Captions [Line Items]
Income taxes paid	24,800	12,400	7,400
Interest paid			$ 283
Interest received	$ 482	$ 320