Trustmark (TRMK) 10-K 19 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Jan. 31, 2019	Jun. 29, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	TRUSTMARK CORP
Entity Central Index Key	36,146
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			$ 1,311
Entity Common Stock, Shares Outstanding		65,179,997
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Trading Symbol	TRMK
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and due from banks (noninterest-bearing)	$ 349,561	$ 335,768
Federal funds sold and securities purchased under reverse repurchase agreements	830	615
Securities available for sale (at fair value)	1,811,813	2,238,635
Securities held to maturity (fair value: $889,733-2018; $1,046,247-2017)	909,643	1,056,486
Loans held for sale (LHFS)	153,799	180,512
Loans held for investment (LHFI)	8,835,868	8,569,967
Less allowance for loan losses, LHFI	79,290	76,733
Net LHFI	8,756,578	8,493,234
Acquired loans	106,932	261,517
Less allowance for loan losses, acquired loans	1,231	4,079
Net acquired loans	105,701	257,438
Net LHFI and acquired loans	8,862,279	8,750,672
Premises and equipment, net	178,668	179,339
Mortgage servicing rights	95,596	84,269
Goodwill	379,627	379,627
Identifiable intangible assets, net	11,112	16,360
Other real estate	34,668	43,228
Other assets	498,864	532,442
Total Assets	13,286,460	13,797,953
Deposits:
Noninterest-bearing	2,937,594	2,978,074
Interest-bearing	8,426,817	7,599,438
Total deposits	11,364,411	10,577,512
Federal funds purchased and securities sold under repurchase agreements	50,471	469,827
Short-term borrowings	79,006	971,049
Long-term Federal Home Loan Bank (FHLB) advances	879	946
Junior subordinated debt securities	61,856	61,856
Other liabilities	138,384	145,062
Total Liabilities	11,695,007	12,226,252
Shareholders' Equity
Common stock, no par value: Authorized: 250,000,000 shares Issued and outstanding: 65,834,395 shares - 2018; 67,746,094 shares - 2017	13,717	14,115
Capital surplus	309,545	369,124
Retained earnings	1,323,870	1,228,187
Accumulated other comprehensive loss, net of tax	(55,679)	(39,725)
Total Shareholders' Equity	1,591,453	1,571,701
Total Liabilities and Shareholders' Equity	$ 13,286,460	$ 13,797,953

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Securities held to maturity, fair value	$ 889,733	$ 1,046,247
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)	65,834,395	67,746,094
Common stock, outstanding (in shares)	65,834,395	67,746,094

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Interest Income
Interest and fees on LHFS & LHFI	$ 395,969	$ 344,625		$ 299,645
Interest and fees on acquired loans	17,115	24,478		30,144
Interest on securities:
Taxable	66,082	76,192		77,614
Tax exempt	2,236	3,001		3,675
Interest on federal funds sold and securities purchased under reverse repurchase agreements	14	33		14
Other interest income	4,196	1,466		988
Total Interest Income	485,612	449,795		412,080
Interest Expense
Interest on deposits	53,936	22,717		12,748
Interest on federal funds purchased and securities sold under repurchase agreements	4,788	4,152		1,717
Other interest expense	7,468	15,376		10,082
Total Interest Expense	66,192	42,245		24,547
Net Interest Income	419,420	407,550		387,533
Provision for loan losses, LHFI	17,993	15,094		10,957
Provision for loan losses, acquired loans	(1,005)	(7,395)		3,757
Net Interest Income After Provision for Loan Losses	402,432	399,851		372,819
Noninterest Income
Service charges on deposit accounts	43,702	44,003	[1]	45,253	[1]
Bank card and other fees	28,905	28,286	[1]	27,906	[1]
Mortgage banking, net	34,674	29,902	[1]	28,212	[1]
Insurance commissions	40,481	38,168	[1]	36,764	[1]
Wealth management	30,338	30,340	[1]	30,492	[1]
Other, net	6,736	13,949	[1]	5,626	[1]
Securities gains (losses), net	0	15	[1]	(310)	[1]
Total Noninterest Income	184,836	184,663	[1]	173,943	[1]
Noninterest Expense
Salaries and employee benefits	238,033	229,265		229,250
Defined benefit plan termination		17,644
Services and fees	66,382	60,893		58,695
Net occupancy - premises	26,703	25,767		24,982
Equipment expense	24,830	24,453		24,225
Other real estate expense	2,002	3,672		586
FDIC assessment expense	9,429	11,010		11,243
Other expense	48,036	57,465		58,317
Total Noninterest Expense	415,415	430,169		407,298
Income Before Income Taxes	171,853	154,345		139,464
Income taxes	22,269	48,715		31,053
Net Income	$ 149,584	$ 105,630		$ 108,411
Earnings Per Share
Basic	$ 2.22	$ 1.56		$ 1.60
Diluted	$ 2.21	$ 1.56		$ 1.60
[1]	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, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income per consolidated statements of income	$ 149,584	$ 105,630	$ 108,411
Net unrealized gains (losses) on available for sale securities and transferred securities:
Net unrealized holding gains (losses) arising during the period	(14,416)	(8,641)	(9,667)
Reclassification adjustment for net (gains) losses realized in net income	0	(9)	191
Change in net unrealized holding loss on securities transferred to held to maturity	2,821	2,915	6,070
Pension and other postretirement benefit plans:
Change in the actuarial loss of pension and other postretirement benefit plans	2,806	(760)	(148)
Reclassification adjustments for changes realized in net income:
Net change in prior service costs	187	154	154
Recognized net loss due to lump sum settlements	122	0	2,412
Change in net actuarial loss	919	1,211	442
Recognized net loss due to defined benefit plan termination	0	10,907	0
Derivatives:
Change in the accumulated gain (loss) on effective cash flow hedge derivatives	373	122	(228)
Reclassification adjustment for (gain) loss realized in net income	(242)	174	370
Other comprehensive income (loss), net of tax	(7,430)	6,073	(404)
Comprehensive income	$ 142,154	$ 111,703	$ 108,007

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, 2015	$ 1,473,057	$ 14,076	$ 361,467	$ 1,142,908	$ (45,394)
Balance (in shares) at Dec. 31, 2015		67,559,128
Net income per consolidated statements of income	108,411	$ 0	0	108,411	0
Other comprehensive income (loss), net of tax	(404)				(404)
Cash dividends paid on common stock ($0.92 per share)	(62,666)	0	0	(62,666)	0
Common stock issued, long-term incentive plan	(1,124)	$ 22	2,155	(3,301)	0
Common stock issued, long-term incentive plan (in shares)		103,112
Repurchase and retirement of common stock	(750)	$ (7)	(743)
Repurchase and retirement of common stock (in shares)		(33,622)
Compensation expense, long-term incentive plan	3,684	$ 0	3,684	0	0
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	$ 0	0	105,630	0
Other comprehensive income (loss), net of tax	6,073				6,073
Cash dividends paid on common stock ($0.92 per share)	(62,795)	0	0	(62,795)	0
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	$ 0	4,309	0	0
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	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 Cuts and Jobs Act of2017 (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

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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, 2018	Dec. 31, 2017		Dec. 31, 2016
Operating Activities
Net income per consolidated statements of income	$ 149,584	$ 105,630		$ 108,411
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses, net	16,988	7,699		14,714
Depreciation and amortization	38,940	38,471		36,613
Net amortization of securities	9,181	10,964		9,664
Securities (gains) losses, net	0	(15)	[1]	310	[1]
Gains on sales of loans, net	(21,615)	(18,933)		(20,531)
Deferred income tax provision	11,740	26,068		18,000
Proceeds from sales of loans held for sale	1,114,020	1,197,821		1,404,852
Purchases and originations of loans held for sale	(1,052,339)	(1,179,187)		(1,392,155)
Originations of mortgage servicing rights	(15,759)	(15,860)		(16,745)
Earnings on bank-owned life insurance	(5,358)	(5,025)		(4,883)
Net change in other assets	(1,891)	23,451		(20,129)
Net change in other liabilities	(1,277)	9,093		7,284
Other operating activities, net	(3,016)	6,430		2,932
Net cash from operating activities	239,198	206,607		148,337
Investing Activities
Proceeds from maturities, prepayments and calls of securities held to maturity	149,308	174,976		277,373
Proceeds from maturities, prepayments and calls of securities available for sale	423,617	467,194		486,915
Proceeds from sales of securities available for sale	0	27,682		24,693
Purchases of securities held to maturity	0	(69,989)		(239,446)
Purchases of securities available for sale	(23,901)	(346,159)		(547,112)
Net proceeds from bank-owned life insurance	1,824	3,623		2,585
Net change in federal funds sold and securities purchased under reverse repurchase agreements	(215)	6,785		(250)
Net change in member bank stock	35,451	4,474		(8,386)
Net change in loans	(140,710)	(608,886)		(677,296)
Purchases of premises and equipment	(14,644)	(13,219)		(10,208)
Proceeds from sales of premises and equipment	772	8,377		6,799
Proceeds from sales of other real estate	20,502	26,849		42,809
Purchases of software	(13,195)	(5,498)		(8,024)
Investments in tax credit and other partnerships	(22)	(5,296)		(116)
Net cash used in business acquisition	0	(19,775)		0
Net cash from investing activities	438,787	(348,862)		(649,664)
Financing Activities
Net change in deposits	786,899	355,342		467,782
Net change in federal funds purchased and securities sold under repurchase agreements	(419,356)	(69,990)		98,775
Net change in short-term borrowings	(905,396)	(67,451)		(150,748)
Payments on long-term FHLB advances	(67)	(65)		(94)
Proceeds from long-term FHLB advances	0	0		250,000
Redemption of junior subordinated debt securities	0	(3,000)		0
Payment of subordinated debt	0	0		(50,000)
Common stock dividends	(62,425)	(62,795)		(62,666)
Repurchase and retirement of common stock	(62,421)	0		(750)
Shares withheld to pay taxes, long-term incentive plan	(1,426)	(1,724)		(1,017)
Net cash from financing activities	(664,192)	150,317		551,282
Net change in cash and cash equivalents	13,793	8,062		49,955
Cash and cash equivalents at beginning of year	335,768	327,706		277,751
Cash and cash equivalents at end of year	$ 349,561	$ 335,768		$ 327,706
[1]	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, 2018
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 196 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 2019 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 Topic 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. If a LHFI that has been specifically reviewed for impairment is deemed impaired, the full difference between the book value and the estimated net realizable value of the collateral is charged off or a specific valuation allowance is established. 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 non-owner 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. Commercial purpose LHFI are charged off when a determination is made that the loan is uncollectible and continuance as a bankable asset is not warranted. Consumer LHFI secured by 1-4 family residential real estate are generally charged off or written down to the fair value of the collateral less cost to sell at no later than 180 days of delinquency. Non-real estate consumer purpose LHFI, including both secured and unsecured loans, are generally charged off by 120 days of delinquency. Consumer revolving lines of credit 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 Topic 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 Topic 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 Topic 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 Topic 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 Topic 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 – Significan

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2018
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 Topic 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 19 – 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, 2018
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, 2018 and 2017 were $112.4 million and $100.8 million, respectively.

Securities Available for Sale a

Securities Available for Sale and Held to Maturity	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 ($ 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, 2018 Cost Gains Losses Value Cost Gains Losses Value 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 December 31, 2017 U.S. Government agency obligations $ 45,763 $ 322 $ (800 ) $ 45,285 $ 3,692 $ 182 $ — $ 3,874 Obligations of states and political subdivisions 78,433 850 (54 ) 79,229 46,039 1,044 (59 ) 47,024 Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 66,634 215 (1,103 ) 65,746 13,539 207 (73 ) 13,673 Issued by FNMA and FHLMC 824,872 827 (11,249 ) 814,450 133,975 210 (1,559 ) 132,626 Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 1,028,176 1,808 (13,194 ) 1,016,790 678,926 1,209 (11,065 ) 669,070 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 218,252 426 (1,543 ) 217,135 180,315 1,102 (1,437 ) 179,980 Total $ 2,262,130 $ 4,448 $ (27,943 ) $ 2,238,635 $ 1,056,486 $ 3,954 $ (14,193 ) $ 1,046,247 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, 2018 and 2017, the net unamortized, unrealized loss on the transferred securities included in accumulated other comprehensive loss in the accompanying balance sheet totaled approximately $15.7 million ($11.8 million, net of tax) and $19.5 million ($12.0 million, net of tax), respectively. Temporarily Impaired Securities The table below includes securities with gross unrealized losses segregated by length of impairment at December 31, 2018 and 2017 ($ in thousands): Less than 12 Months 12 Months or More Total Gross Gross Gross Estimated Unrealized Estimated Unrealized Estimated Unrealized December 31, 2018 Fair Value Losses Fair Value Losses Fair Value Losses 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 ) December 31, 2017 U.S. Government agency obligations $ 5,214 $ (113 ) $ 29,432 $ (687 ) $ 34,646 $ (800 ) Obligations of states and political subdivisions 19,345 (80 ) 3,874 (33 ) 23,219 (113 ) Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 37,304 (351 ) 29,446 (825 ) 66,750 (1,176 ) Issued by FNMA and FHLMC 506,410 (4,219 ) 369,060 (8,589 ) 875,470 (12,808 ) Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 755,013 (7,668 ) 534,955 (16,591 ) 1,289,968 (24,259 ) Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 230,898 (1,719 ) 55,288 (1,261 ) 286,186 (2,980 ) Total $ 1,554,184 $ (14,150 ) $ 1,022,055 $ (27,986 ) $ 2,576,239 $ (42,136 ) 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, 2018. There were no other-than-temporary impairments for the years ended December 31, 2018, 2017 and 2016. 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 2018 2017 2016 Proceeds from calls and sales of securities $ — $ 27,682 $ 24,693 Gross realized gains — 16 32 Gross realized losses — (1 ) (342 ) Securities Pledged Securities with a carrying value of $2.144 billion and $1.834 billion at December 31, 2018 and 2017, respectively, were pledged to collateralize public deposits and securities sold under repurchase agreements and for other purposes as permitted by law. At both December 31, 2018 and 2017, none of these securities were pledged under the Federal Reserve Discount Window program to provide additional contingency funding capacity. Contractual Maturities The amortized cost and estimated fair value of securities available for sale and held to maturity at December 31, 2018, by contractual maturity, are shown below ($ 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 $ 24,449 $ 24,475 $ 170 $ 170 Due after one year through five years 27,271 27,481 35,073 35,193 Due after five years through ten years 3,056 2,989 4,276 4,350 Due after ten years 26,962 26,066 — — 81,738 81,011 39,519 39,713 Mortgage-backed securities 1,772,791 1,730,802 870,124 850,020 Total $ 1,854,529 $ 1,811,813 $ 909,643 $ 889,733

LHFI and Allowance for Loan Los

LHFI and Allowance for Loan Losses, LHFI	12 Months Ended
	Dec. 31, 2018
Accounts Notes Loans And Financing Receivable Gross Allowance And Net [Abstract]
LHFI and Allowance for Loan Losses, LHFI	Note 5 – LHFI and Allowance for Loan Losses, LHFI At December 31, 2018 and 2017, LHFI consisted of the following ($ in thousands): December 31, 2018 2017 Loans secured by real estate: Construction, land development and other land $ 1,056,601 $ 987,624 Secured by 1-4 family residential properties 1,825,492 1,675,311 Secured by nonfarm, nonresidential properties 2,220,914 2,193,823 Other real estate secured 543,820 517,956 Commercial and industrial loans 1,538,715 1,570,345 Consumer loans 182,448 171,918 State and other political subdivision loans 973,818 952,483 Other loans 494,060 500,507 LHFI 8,835,868 8,569,967 Less allowance for loan losses, LHFI 79,290 76,733 Net LHFI $ 8,756,578 $ 8,493,234 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, 2018, 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, 2018 and 2017, loans to certain executive officers and directors, including their immediate families and companies in which they are principal owners, totaled $49.0 million and $59.9 million, respectively. During 2018, $440.5 million of new loan advances were made, while repayments were $451.4 million. There were no increases in loans due to changes in executive officers and directors. Nonaccrual and Past Due LHFI At December 31, 2018 and 2017, the carrying amounts of nonaccrual LHFI were $61.6 million and $67.6 million, respectively. Included in these amounts were $16.7 million and $23.2 million, respectively, of nonaccrual LHFI classified as TDRs. No material interest income was recognized in the income statement on nonaccrual LHFI for each of the years in the three-year period ended December 31, 2018. The following tables provide an aging analysis of past due and nonaccrual LHFI by loan type at December 31, 2018 and 2017 ($ in thousands): 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. December 31, 2017 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 $ 391 $ 1 $ — $ 392 $ 2,105 $ 985,127 $ 987,624 Secured by 1-4 family residential properties 6,412 2,084 1,917 10,413 19,022 1,645,876 1,675,311 Secured by nonfarm, nonresidential properties 2,319 256 — 2,575 12,608 2,178,640 2,193,823 Other real estate secured — — — — 212 517,744 517,956 Commercial and industrial loans 759 1,233 12 2,004 33,338 1,535,003 1,570,345 Consumer loans 2,141 255 242 2,638 135 169,145 171,918 State and other political subdivision loans 350 39 — 389 — 952,094 952,483 Other loans 18 4 — 22 155 500,330 500,507 Total $ 12,390 $ 3,872 $ 2,171 $ 18,433 $ 67,575 $ 8,483,959 $ 8,569,967 (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 $500 thousand or more, which are specifically reviewed for impairment and deemed impaired, and all LHFI classified as TDRs in accordance with FASB ASC Topic 310-10-50-20, and are primarily collateral dependent loans. Fair value estimates for collateral dependent loans are derived from appraised values based on the current market value or as is value of the collateral, normally from recently received and reviewed appraisals. Current appraisals are ordered on an annual basis based on the inspection date or more often if market conditions necessitate. Appraisals are obtained from state-certified appraisers and are based on certain assumptions, which may include construction or development status and the highest and best use of the property. These appraisals are reviewed by Trustmark’s Appraisal Review Department to ensure they are acceptable, and values are adjusted down for costs associated with asset disposal. Once this estimated net realizable value has been determined, the value used in the impairment assessment is updated. At the time a LHFI that has been specifically reviewed for impairment is deemed to be impaired, the full difference between book value and the most likely estimate of the collateral’s net realizable value is either charged off or a specific reserve is established. As subsequent events dictate and estimated net realizable values change, further adjustments may be necessary. No material interest income was recognized in the accompanying consolidated statements of income on impaired LHFI for each of the years in the three-year period ended December 31, 2018. At December 31, 2018 and 2017, individually evaluated for impaired LHFI consisted of the following ($ in thousands): 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 December 31, 2017 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 $ 1,704 $ 1,206 $ 199 $ 1,405 $ 75 $ 1,923 Secured by 1-4 family residential properties 6,031 160 4,576 4,736 1,331 4,693 Secured by nonfarm, nonresidential properties 15,205 10,027 396 10,423 165 8,321 Other real estate secured — — — — — — Commercial and industrial loans 36,874 31,281 518 31,799 131 22,734 Consumer loans 17 — 17 17 — 9 State and other political subdivision loans — — — — — — Other loans 556 — 556 556 41 325 Total $ 60,387 $ 42,674 $ 6,262 $ 48,936 $ 1,743 $ 38,005 Troubled Debt Restructurings At December 31, 2018, 2017 and 2016, LHFI classified as TDRs totaled $28.2 million, $23.9 million and $14.5 million, respectively, and were primarily comprised of credits with interest-only payments for an extended period of time which totaled $23.8 million, $20.5 million and $9.8 million, respectively. The remaining TDRs at December 31, 2018, 2017 and 2016 resulted from bankruptcies or from payment or maturity extensions. Trustmark had $4.4 million of unused commitments on TDRs at December 31, 2018, compared to no material unused commitments on TDRs at December 31, 2017 and 2016. For TDRs, Trustmark had a related loan loss allowance of $2.3 million at December 31, 2018, $458 thousand at December 31, 2017 and $2.2 million at December 31, 2016. 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 $18.4 million, $127 thousand and $1.0 million for the years ended December 31, 2018, 2017 and 2016, respectively. The following tables illustrate the impact of modifications classified as TDRs for the periods presented ($ in thousands): 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 Year Ended December 31, 2016 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 $ 14 $ 14 Secured by 1-4 family residential properties 18 1,386 1,391 Secured by nonfarm, nonresidential properties 2 717 717 Commercial and industrial loans 5 10,043 9,982 Consumer loans 1 2 2 Total 27 $ 12,162 $ 12,106 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 period ($ in thousands): Years Ended December 31, 2018 2017 2016 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 5 734 4 78 1 — Commercial and industrial loans 6 15,178 3 9,526 2 2,154 Consumer loans 1 1 — — — — Total 13 $ 15,935 7 $ 9,604 3 $ 2,154 Trustmark’s TDRs have resulted primarily from allowing the borrower to pay interest-only for an extended period of time 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, 2018, 2017 and 2016 ($ in thousands): 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 December 31, 2016 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 405 $ 405 Secured by 1-4 family residential properties — 2,873 2,873 Secured by nonfarm, nonresidential properties — 881 881 Commercial and industrial loans 53 10,266 10,319 Consumer loans — 2 2 Total TDRs $ 53 $ 14,427 $ 14,480 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, nonaccrual relationships of $500 thousand or more that are rated in one of the classified categories 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 $100 thousand or more. In addition, a semi-annual review of significant development, commercial construction, multi-family and non-owner occupied projects is performed. This review assesses each particular project with respect to location, project valuations, progress of completion, leasing status, current financial information, rents, operating expenses, cash flow, adherence to budget and projections and other information as applicable. Summary results are reviewed by Senior and Regional Credit Officers in addition to the Chief Credit Officer with a determination made as to the appropriateness of existing risk ratings and accrual status. Consumer Credits Consumer LHFI that do not meet a minimum custom credit score are reviewed quarterly by Management. The Retail Credit Review Committee reviews the volume and percentage of approvals that did not meet the minimum passing custom score by region, individual location, and officer to ensure that Trustmark continues to originate quality loans. Trustmark monitors the levels and severity of past due consumer LHFI on a daily basis through its collection activities. A detailed assessment of consumer LHFI delinquencies is performed monthly at both a product and market level by delivery channel, which incorporates the perceived level of risk at time of underwriting. The tables below present LHFI by loan type and credit quality indicator at December 31, 2018 and 2017 ($ in thousands): December 31, 2018 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 $ 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 Days or More 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 December 31, 2017 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 $ 922,563 $ 316 $ 3,780 $ 222 $ 926,881 Secured by 1-4 family residential properties 127,405 134 4,948 76 132,563 Secured by nonfarm, nonresidential properties 2,135,749 6,684 50,785 527 2,193,745 Other real estate secured 517,036 — 517 — 517,553 Commercial and industrial loans 1,437,590 28,780 103,089 886 1,570,345 Consumer loans — — — — — State and other political subdivision loans 936,420 5,850 10,213 — 952,483 Other loans 478,083 — 16,390 108 494,581 Total $ 6,554,846 $ 41,764 $ 189,722 $ 1,819 $ 6,788,151 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 $ 60,240 $ 342 $ — $ 161 $ 60,743 $ 987,624 Secured by 1-4 family residential properties 1,516,691 7,874 1,809 16,374 1,542,748 1,675,311 Secured by nonfarm, nonresidential properties 78 — — — 78 2,193,823 Other real estate secured 403 — — — 403 517,956 Commercial and industrial loans — — — — — 1,570,345 Consumer loans 169,146 2,396 242 134 171,918 171,918 State and other political subdivision loans — — — — — 952,483 Other loans 5,926 — — — 5,926 500,507 Total $ 1,752,484 $ 10,612 $ 2,051 $ 16,669 $ 1,781,816 $ 8,569,967 Past Due LHFS LHFS past due 90 days or more totaled $37.4 million and $35.5 million at December 31, 2018 and 2017, respectively. Trustmark did not exercise its buy-back option on any delinquent loans serviced for GNMA during 2018 or 2017. 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 – Non-Owner 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 determination of the risk measurement for each qualitative factor is done for all markets combined. The resulting estimated reserve factor is then applied to each pool. 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, 2018 and 2017 ($ in thousands): 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 December 31, 2017 Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ 75 $ 7,790 $ 7,865 Secured by 1-4 family residential properties 1,331 9,543 10,874 Secured by nonfarm, nonresidential properties 165 23,263 23,428 Other real estate secured — 2,790 2,790 Commercial and industrial loans 131 22,720 22,851 Consumer loans — 3,470 3,470 State and other political subdivision loans — 789 789 Other loans 41 4,625 4,666 Total allowance for loan losses, LHFI $ 1,743 $ 74,990 $ 76,733 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, 2018 and 2017 ($ in thousands): 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 December 31, 2017 LHFI Evaluated for Impairment Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ 1,405 $ 986,219 $ 987,624 Secured by 1-4 family residential properties 4,736 1,670,575 1,675,311 Secured by nonfarm, nonresidential properties 10,423 2,183,400 2,193,823 Other real estate secured — 517,956 517,956 Commercial and industrial loans 31,799 1,538,546 1,570,345 Consumer loans 17 171,901 171,918 State and other political subdivision loans — 952,483 952,483 Other loans 556 499,951 500,507 Total $

Acquired Loans

Acquired Loans	12 Months Ended
	Dec. 31, 2018
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. Loans acquired in the Reliance merger completed on April 7, 2017 were evaluated using a fair value process to determine the degree of credit deterioration since origination and the collectibility of contractually required payments. Approximately $7.9 million of the loans acquired in the Reliance merger exhibited evidence of significant credit deterioration since origination and for which it was probable at acquisition that Trustmark would not be able to collect all contractually required payments. These loans were accounted for as acquired impaired loans under FASB ASC Topic 310-30. At December 31, 2018 and 2017, acquired loans consisted of the following ($ in thousands): December 31, 2018 2017 Loans secured by real estate: Construction, land development and other land $ 5,878 $ 23,586 Secured by 1-4 family residential properties 22,556 61,751 Secured by nonfarm, nonresidential properties 47,979 114,694 Other real estate secured 8,253 16,746 Commercial and industrial loans 15,267 31,506 Consumer loans 1,356 2,600 Other loans 5,643 10,634 Acquired loans 106,932 261,517 Less allowance for loan losses, acquired loans 1,231 4,079 Net acquired loans $ 105,701 $ 257,438 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, 2017 $ 218,107 $ 42,743 Transfers (2) — (36,719 ) Additions (3) 7,899 109,548 Accretion to interest income 14,924 1,578 Payments received, net (68,317 ) (39,208 ) Other (4) (361 ) (74 ) Change in allowance for loan losses, acquired loans 7,318 — Carrying value, net at December 31, 2017 179,570 77,868 Transfers (5)(2) (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 (1) “Acquired Not ASC 310-30” loans consist of loans that are not in scope for FASB ASC Topic 310-30. (2) “Acquired Not ASC 310-30” loans transferred to LHFI due to the discount on these loans being fully amortized. (3) Loans acquired in the Reliance merger on April 7, 2017. (4) Includes miscellaneous timing adjustments as well as acquired loan terminations through foreclosure, charge-off and other terminations. (5) During 2018, Trustmark transferred the remaining loans acquired in the Heritage acquisition on April 11, 2015, the Bay Bank merger on March 16, 2012 and the Reliance merger on April 7, 2017 from acquired impaired loans to LHFI. Under FASB ASC Topic 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, 2018 2017 2016 Accretable yield at beginning of period $ (31,426 ) $ (38,918 ) $ (52,672 ) Additions due to acquisition (1) — (784 ) — Accretion to interest income 9,514 14,924 18,405 Disposals, net 3,926 2,868 6,488 Transfers (2) 5,874 — — Reclassification from nonaccretable difference (3) (5,610 ) (9,516 ) (11,139 ) Accretable yield at end of period $ (17,722 ) $ (31,426 ) $ (38,918 ) (1) Accretable yield on loans acquired from Reliance on April 7, 2017. (2) During 2018, Trustmark transferred the remaining loans acquired in the Heritage acquisition on April 11, 2015, the Bay Bank merger on March 16, 2012 and the Reliance merger on April 7, 2017 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, 2018 2017 2016 Balance at beginning of period $ 4,079 $ 11,397 $ 11,992 Transfers (1) (1,554 ) — — Provision for loan losses, acquired loans (1,005 ) (7,395 ) 3,757 Net (charge-offs) recoveries (289 ) 77 (4,352 ) Balance at end of period $ 1,231 $ 4,079 $ 11,397 (1) The allowance for loan losses balance related to the remaining loans acquired in the Heritage acquisition, the Bay Bank merger and the Reliance merger, 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, 2018 and 2017 ($ in thousands): 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 Topic 310-30. December 31, 2017 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 $ 17,150 $ 234 $ 4,690 $ 264 $ 22,338 Secured by 1-4 family residential properties 14,021 298 3,029 — 17,348 Secured by nonfarm, nonresidential properties 95,147 1,400 17,583 530 114,660 Other real estate secured 12,730 102 3,031 477 16,340 Commercial and industrial loans 22,157 15 7,585 1,749 31,506 Consumer loans — — — — — Other loans 5,874 18 4,742 — 10,634 Total acquired loans $ 167,079 $ 2,067 $ 40,660 $ 3,020 $ 212,826 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 $ 1,188 $ 46 $ 14 $ — $ 1,248 $ 23,586 Secured by 1-4 family residential properties 42,008 1,687 584 124 44,403 61,751 Secured by nonfarm, nonresidential properties 34 — — — 34 114,694 Other real estate secured 406 — — — 406 16,746 Commercial and industrial loans — — — — — 31,506 Consumer loans 2,428 172 — — 2,600 2,600 Other loans — — — — — 10,634 Total acquired loans $ 46,064 $ 1,905 $ 598 $ 124 $ 48,691 $ 261,517 (1) Acquired loans not accounted for under FASB ASC Topic 310-30 . The following tables provide an aging analysis of contractually past due and nonaccrual acquired loans by loan type at December 31, 2018 and 2017 ($ in thousands): 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 Topic 310-30. December 31, 2017 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 $ 34 $ 90 $ 861 $ 985 $ — $ 22,601 $ 23,586 Secured by 1-4 family residential properties 1,691 614 654 2,959 302 58,490 61,751 Secured by nonfarm, nonresidential properties 467 73 898 1,438 — 113,256 114,694 Other real estate secured 132 — — 132 — 16,614 16,746 Commercial and industrial loans — — — — 2 31,504 31,506 Consumer loans 16 156 — 172 — 2,428 2,600 Other loans — — 21 21 — 10,613 10,634 Total acquired loans $ 2,340 $ 933 $ 2,434 $ 5,707 $ 304 $ 255,506 $ 261,517 (1) Past due 90 days or more but still accruing interest. (2) Acquired loans not accounted for under FASB ASC Topic 310-30.

Premises and Equipment, Net

Premises and Equipment, Net	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Premises and Equipment, Net	Note 7 – Premises and Equipment, Net At December 31, 2018 and 2017, premises and equipment consisted of the following ($ in thousands): December 31, 2018 2017 Land $ 52,779 $ 52,335 Buildings and leasehold improvements 202,912 197,372 Furniture and equipment 169,652 166,071 Total cost of premises and equipment 425,343 415,778 Less accumulated depreciation and amortization 247,160 237,425 Premises and equipment, net 178,183 178,353 Assets held for sale 485 986 Total premises and equipment, net $ 178,668 $ 179,339 Assets held for sale consisted of three closed branches at December 31, 2018 and 2017. These properties were transferred from premises and equipment, net to assets held for sale due to Trustmark’s intent to sell these properties over the next twelve months as a result of its strategic branch initiatives. As a result, property valuation adjustments of $173 thousand, $338 thousand and $750 thousand were recognized and included in other expense for 2018, 2017 and 2016, respectively. Depreciation and amortization of premises and equipment totaled $14.3 million in both 2018 and 2017 and $13.2 million in 2016.

Mortgage Banking

Mortgage Banking	12 Months Ended
	Dec. 31, 2018
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, 2018 2017 Balance at beginning of period $ 84,269 $ 80,239 Origination of servicing assets 15,759 15,860 Change in fair value: Due to market changes 7,342 (1,050 ) Due to runoff (11,774 ) (10,780 ) Balance at end of period $ 95,596 $ 84,269 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, 2018, the fair value of the MSR included an assumed average prepayment speed of 8.19 CPR and an average discount rate of 10.04% compared to an assumed average prepayment speed of 9.14 CPR and an average discount rate of 10.28% at December 31, 2017. 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 2018, 2017 and 2016, Trustmark sold $1.092 billion, $1.179 billion and $1.384 billion, respectively, of residential mortgage loans. Pretax gains on these sales totaled $21.6 million in 2018, $18.9 million in 2017 and $20.5 million in 2016. Trustmark receives annual servicing fee income approximating 0.33% of the outstanding balance of the underlying loans, which totaled $21.9 million in 2018, $21.4 million in 2017 and $20.4 million in 2016. The pretax gains on the sale of residential mortgage loans and the annual servicing fee are both recorded to noninterest income in mortgage banking, net in the accompanying consolidated statements of income. The investors and the securitization trusts have no recourse to the assets of Trustmark for failure of debtors to pay when due. The table below details the mortgage loans sold and serviced for others at December 31, 2018 and 2017 ($ in thousands): December 31, 2018 2017 Federal National Mortgage Association $ 4,204,336 $ 4,128,614 Government National Mortgage Association 2,537,238 2,421,456 Federal Home Loan Mortgage Corporation 71,343 47,071 Other 21,957 26,864 Total mortgage loans sold and serviced for others $ 6,834,874 $ 6,624,005 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. Currently, putback requests primarily relate to 2009 through 2013 vintage mortgage loans. The total mortgage loan servicing putback expenses were included in other expense. Changes in the reserve for mortgage loan servicing putback expense for mortgage loans were as follows for the periods presented ($ in thousands): Years Ended December 31, 2018 2017 2016 Balance at beginning of period $ 1,000 $ 1,130 $ 1,685 Provision for putback expenses — (836 ) 420 Other (1) — 706 (975 ) Balance at end of period $ 1,000 $ 1,000 $ 1,130 (1) Includes fair value adjustments for loans transferred due to underwriting issues as well as adjustments based on Trustmark’s mortgage loan servicing putback reserve analysis. 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, 2018
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, 2018 and 2017 ($ in thousands): General Banking Insurance Total Balance as of January 1, 2017 $ 321,132 $ 45,024 $ 366,156 Goodwill from Reliance merger during 2017 13,471 — 13,471 Balance as of December 31, 2017 334,603 45,024 379,627 Adjustment during 2018 — — — Balance as of December 31, 2018 $ 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. During 2017, Trustmark recorded $13.5 million as goodwill from its merger with Reliance. The Insurance Segment includes TNB’s wholly-owned retail insurance subsidiary that offers a diverse mix of insurance products and services. Trustmark performed goodwill impairment tests for the General Banking and Insurance Segments during 2018, 2017 and 2016. Based on these tests, Trustmark concluded that the fair value of both the General Banking and Insurance Segments substantially exceeded the book value and no impairment charge was required. Identifiable Intangible Assets At December 31, 2018 and 2017, identifiable intangible assets consisted of the following ($ in thousands): December 31, 2018 December 31, 2017 Gross Accumulated Net Carrying Gross Carrying Accumulated Net Carrying Amount Amortization Amount Amount Amortization Amount Core deposit intangibles $ 87,674 $ 78,353 $ 9,321 $ 87,674 $ 73,494 $ 14,180 Insurance intangibles 13,824 12,348 1,476 13,824 12,026 1,798 Banking charters 1,325 1,010 315 1,325 943 382 Borrower relationship intangible — — — 690 690 — Total $ 102,823 $ 91,711 $ 11,112 $ 103,513 $ 87,153 $ 16,360 Trustmark recorded $5.2 million of amortization of identifiable intangible assets in 2018, $6.2 million in 2017 and $6.9 million in 2016. Trustmark estimates that amortization expense for identifiable intangible assets will be $4.0 million in 2019, $2.7 million in 2020, $1.9 million in 2021, $1.1 million in 2022 and $427 thousand in 2023. Trustmark continually evaluates whether events and circumstances have occurred that indicate that identifiable intangible assets have become impaired. Measurement of any impairment of such identifiable intangible assets is based on the fair values of those assets. There were no impairment losses on identifiable intangible assets recorded during 2018, 2017 or 2016. The following table illustrates the carrying amounts and remaining weighted-average amortization periods of identifiable intangible assets as of December 31, 2018 ($ in thousands): Remaining Weighted- Average Net Carrying Amortization Amount Period in Core deposit intangibles $ 9,321 4.4 Insurance intangibles 1,476 15.5 Banking charters 315 4.7 Total $ 11,112 5.9

Other Real Estate

Other Real Estate	12 Months Ended
	Dec. 31, 2018
Other Real Estate And Foreclosed Assets [Abstract]
Other Real Estate	Note 10 – Other Real Estate At December 31, 2018, 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, 2018 2017 2016 (1) Balance at beginning of period $ 43,228 $ 62,051 $ 78,828 Additions (2) 12,115 9,235 24,525 Disposals (19,802 ) (24,762 ) (36,801 ) Write-downs (873 ) (3,296 ) (4,501 ) Balance at end of period $ 34,668 $ 43,228 $ 62,051 Gain (losses), net on the sale of other real estate included in other real estate expense $ 700 $ 2,087 $ 7,031 (1) The changes and gains, net on other real estate for the year ended December 31, 2016 include covered other real estate. (2) For the year ended December 31, 2017, additions to other real estate included $475 thousand of other real estate acquired in the Reliance merger on April 7, 2017. At December 31, 2018 and 2017, other real estate by type of property consisted of the following ($ in thousands): December 31, 2018 2017 Construction, land development and other land properties $ 16,206 $ 27,491 1-4 family residential properties 4,983 5,081 Nonfarm, nonresidential properties 13,296 10,468 Other real estate properties 183 188 Total other real estate $ 34,668 $ 43,228 At December 31, 2018 and 2017, other real estate by geographic location consisted of the following ($ in thousands): December 31, 2018 2017 Alabama $ 6,873 $ 11,714 Florida 8,771 13,937 Mississippi (1) 17,255 14,260 Tennessee (2) 1,025 2,535 Texas 744 782 Total other real estate $ 34,668 $ 43,228 (1) Mississippi includes Central and Southern Mississippi Regions. (2) Tennessee includes Memphis, Tennessee and Northern Mississippi Regions. At December 31, 2018 and 2017, the balance of other real estate included $5.0 million and $5.1 million, respectively, of foreclosed residential real estate properties recorded as a result of obtaining physical possession of the

Deposits

Deposits	12 Months Ended
	Dec. 31, 2018
Deposits [Abstract]
Deposits	Note 11 – Deposits At December 31, 2018 and 2017, deposits consisted of the following ($ in thousands): December 2018 2017 Noninterest-bearing demand $ 2,937,594 $ 2,978,074 Interest-bearing demand 2,633,259 2,432,814 Savings 3,905,659 3,408,183 Time 1,887,899 1,758,441 Total $ 11,364,411 $ 10,577,512 Interest expense on deposits by type consisted of the following for the periods presented ($ in thousands): Years Ended December 31, 2018 2017 2016 Interest-bearing demand $ 18,479 $ 6,820 $ 3,297 Savings 17,980 6,047 2,657 Time 17,477 9,850 6,794 Total $ 53,936 $ 22,717 $ 12,748 Time deposits that exceed the FDIC insurance limit of $250 thousand totaled $406.6 million and $342.3 million at December 31, 2018 and 2017, respectively. The maturities of interest-bearing deposits at December 31, 2018, are as follows ($ in thousands): 2019 $ 1,478,845 2020 295,596 2021 55,927 2022 33,616 2023 and thereafter 23,915 Total time deposits 1,887,899 Interest-bearing deposits with no stated maturity 6,538,918 Total interest-bearing deposits $ 8,426,817

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Borrowings	Note 12 - 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 Topic 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 $163.3 million and $200.9 million at December 31, 2018 and 2017, respectively. As of December 31, 2018, all repurchase agreements were short-term and consisted primarily of sweep repurchase arrangements, under which excess deposits are “swept” into overnight repurchase agreements with Trustmark. The following table presents the securities sold under repurchase agreements by collateral pledged at December 31, 2018 and 2017 ($ in thousands): December 31, 2018 2017 Mortgage-backed securities Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA $ 6,721 $ 68,246 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 38,788 50,448 Total securities sold under repurchase agreements $ 45,509 $ 118,694 Short-Term Borrowings At December 31, 2018 and 2017, short-term borrowings consisted of the following ($ in thousands): December 2018 2017 FHLB advances $ — $ 900,013 Serviced GNMA loans eligible for repurchase 61,564 48,211 Other 17,442 22,825 Total short-term borrowings $ 79,006 $ 971,049 At December 31, 2018, Trustmark had no outstanding short-term FHLB advances. Trustmark had four outstanding short-term FHLB advances totaling $900.0 million with the FHLB of Dallas at December 31, 2017. Two of these outstanding advances with the FHLB of Dallas had fixed interest rates of 1.44% and 1.48% and balances of $250.0 million and $150.0 million, respectively. At December 31, 2017, these two fixed rate advances had a weighted-average remaining maturity of 58 days with a weighted-average cost of 1.45% during 2017. At December 31, 2017, Trustmark had two outstanding short-term FHLB advance with a balance of $250.0 million each with the FHLB of Dallas that repriced on a monthly basis. Trustmark paid off the outstanding short-term advance due to mature on May 25, 2018 in full on March 2, 2018. For the remaining outstanding short-term FHLB advance, Trustmark paid off $125.0 million on May 4, 2018 with the remaining balance of $125.0 million maturing on October 19, 2018. At December 31, 2018 and 2017, Trustmark had $2.827 billion and $1.771 billion, respectively, available in additional short and long-term borrowing capacity from the FHLB of Dallas. At December 31, 2018, Trustmark had no outstanding short-term advances with the FHLB of Atlanta compared to one outstanding short-term FHLB advance with the FHLB of Atlanta, which was assumed through the BancTrust merger, at December 31, 2017. The short-term FHLB advance outstanding at December 31, 2017 had a balance of $13 thousand with a fixed interest rate of 6.12% and a remaining maturity of 72 days. Trustmark has a non-member status and no additional borrowing capacity with the FHLB of Atlanta. Interest expense on short-term FHLB advances totaled $4.4 million in 2018, $11.4 million in 2017 and $1.8 million in 2016. Long-Term FHLB Advances At December 31, 2018 and 2017, Trustmark had no outstanding long-term FHLB advances with the FHLB of Dallas. At December 31, 2018, Trustmark had two outstanding long-term FHLB advances totaling $879 thousand with the FHLB of Atlanta, compared to two outstanding long-term FHLB advances totaling $946 thousand with the FHLB of Atlanta at December 31, 2017. 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 $153 thousand and $726 thousand at December 31, 2018 and $171 thousand and $775 thousand at December 31, 2017. At December 31, 2018, these advances had a weighted-average remaining maturity of 3.41 years with a weighted-average cost of 0.63% during 2018. At December 31, 2017, the outstanding long-term advances had a weighted-average remaining maturity of 4.44 years with a weighted-average cost of 0.63% during 2017. There was no fair market value adjustment associated with the BancTrust merger included in the long-term FHLB advances at December 31, 2018 and 2017. Trustmark’s long-term FHLB advances are collateralized by securities held in safekeeping with the FHLB of Atlanta. Trustmark incurred $6 thousand of interest expense on long-term FHLB advances in 2018, compared to $566 thousand of interest expense in 2017 and $2.1 million of interest expense in 2016. 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 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, 2018 and 2017, 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, 2018 and 2017, 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 2018, net income for the Trust equaled $74 thousand resulting from interest income from the junior subordinated debt securities issued by Trustmark to the Trust, compared with net income of $55 thousand during 2017 and $45 thousand during 2016. Dividends issued to Trustmark by the Trust during 2018 totaled $74 thousand, compared to $55 thousand during 2017 and $45 thousand during 2016.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Revenue from Contracts with Customers	Note 13 – 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, 2018 Year Ended December 31, 2017 (1) Year Ended December 31, 2016 (1) Topic 606 Not Topic 606 (2) Total Topic 606 Not Topic 606 (2) Total Topic 606 Not Topic 606 (2) Total General Banking Segment Service charges on deposit accounts $ 43,699 $ — $ 43,699 $ 44,001 $ — $ 44,001 $ 45,252 $ — $ 45,252 Bank card and other fees 26,926 1,897 28,823 27,979 250 28,229 27,230 663 27,893 Mortgage banking, net — 34,674 34,674 — 29,902 29,902 — 28,212 28,212 Wealth management 296 — 296 210 — 210 566 — 566 Other, net 6,826 (196 ) 6,630 6,565 7,258 13,823 7,185 (1,739 ) 5,446 Security gains (losses), net — — — — 15 15 — (310 ) (310 ) Total noninterest income $ 77,747 $ 36,375 $ 114,122 $ 78,755 $ 37,425 $ 116,180 $ 80,233 $ 26,826 $ 107,059 Wealth Management Segment Service charges on deposit accounts $ 3 $ — $ 3 $ 2 $ — $ 2 $ 1 $ — $ 1 Bank card and other fees 82 — 82 57 — 57 13 — 13 Wealth management 30,042 — 30,042 30,130 — 30,130 29,926 — 29,926 Other, net 4 97 101 1 95 96 83 94 177 Total noninterest income $ 30,131 $ 97 $ 30,228 $ 30,190 $ 95 $ 30,285 $ 30,023 $ 94 $ 30,117 Insurance Segment Insurance commissions $ 40,481 $ — $ 40,481 $ 38,168 $ — $ 38,168 $ 36,764 $ — $ 36,764 Other, net 5 — 5 30 — 30 3 — 3 Total noninterest income $ 40,486 $ — $ 40,486 $ 38,198 $ — $ 38,198 $ 36,767 $ — $ 36,767 Consolidated Service charges on deposit accounts $ 43,702 $ — $ 43,702 $ 44,003 $ — $ 44,003 $ 45,253 $ — $ 45,253 Bank card and other fees 27,008 1,897 28,905 28,036 250 28,286 27,243 663 27,906 Mortgage banking, net — 34,674 34,674 — 29,902 29,902 — 28,212 28,212 Insurance commissions 40,481 — 40,481 38,168 — 38,168 36,764 — 36,764 Wealth management 30,338 — 30,338 30,340 — 30,340 30,492 — 30,492 Other, net 6,835 (99 ) 6,736 6,596 7,353 13,949 7,271 (1,645 ) 5,626 Security gains (losses), net — — — — 15 15 — (310 ) (310 ) Total noninterest income $ 148,364 $ 36,472 $ 184,836 $ 147,143 $ 37,520 $ 184,663 $ 147,023 $ 26,920 $ 173,943 (1) 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. (2) 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, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Note 14 – 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, 2018 2017 2016 Current Federal $ 4,532 $ 16,959 $ 10,355 State 5,997 5,687 2,698 Deferred Federal 9,392 7,280 15,647 State 2,348 1,820 2,353 Income tax provision excluding deferred tax asset revaluation and reversal of valuation allowance 22,269 31,746 31,053 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 $ 22,269 $ 48,715 $ 31,053 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, 2018 2017 2016 Income tax computed at statutory tax rate $ 36,089 $ 54,021 $ 48,812 Tax exempt interest (4,533 ) (7,611 ) (6,780 ) Nondeductible interest expense 416 407 201 State income taxes, net 4,738 3,697 1,754 Income tax credits, net (15,404 ) (15,793 ) (16,183 ) Death benefit gains (268 ) (3,268 ) — Reversal of valuation allowance — (8,650 ) — Re-measurement of deferred tax assets — 25,619 — Other 1,231 293 3,249 Income tax provision $ 22,269 $ 48,715 $ 31,053 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, 2018 and 2017, which are included in other assets on the accompanying consolidated balance sheets ($ in thousands): December 31, 2018 2017 Deferred tax assets: Loan purchase accounting $ 1,564 $ 3,638 Other real estate 7,284 13,403 Allowance for loan losses 20,638 20,203 Deferred compensation 15,607 15,184 Realized built-in losses 12,182 12,932 Securities 3,929 4,869 Pension and other postretirement benefit plans 4,108 5,453 Interest on nonaccrual loans 806 774 Unrealized losses on securities available for sale 10,679 5,874 Stock-based compensation 2,192 2,067 Federal carryovers 1,606 4,569 Other 9,179 8,964 Gross deferred tax asset 89,774 97,930 Deferred tax liabilities: Goodwill and other identifiable intangibles 16,229 16,729 Premises and equipment 12,109 11,877 Mortgage servicing rights 14,415 9,964 Securities 1,519 1,345 Other 5,600 5,040 Gross deferred tax liability 49,872 44,955 Net deferred tax asset $ 39,902 $ 52,975 The following table provides a summary of the changes during the 2018 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, 2018 $ 1,105 Change due to tax positions taken during the current year 282 Change due to tax positions taken during a prior year 56 Change due to the lapse of applicable statute of limitations during the current year (194 ) Change due to settlements with taxing authorities during the current year — Balance at December 31, 2018 $ 1,249 Accrued interest, net of federal benefit, at December 31, 2018 $ 212 Unrecognized tax benefits that would impact the effective tax rate, if recognized, at December 31, 2018 $ 988 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 2012 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, 2018
Compensation And Retirement Disclosure [Abstract]
Defined Benefit and Other Postretirement Benefits	Note 15 – 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 plan assets and a one-time pension settlement expense was recognized totaling $17.6 million. Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions To satisfy commitments made by Trustmark to associates covered through plans obtained in acquisitions and subsequently merged into the Plan (collectively, the “Continuing Associates”), on July 26, 2016, the Board of Directors of Trustmark also approved the spin-off of the portion of the Plan associated with the accrued benefits of the Continuing Associates into a new plan titled the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions (the “Continuing Plan”), effective as of December 30, 2016, immediately prior to the termination of the Plan. The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for Trustmark’s tax-qualified defined benefit pension plans (the Continuing Plan and the Plan) for the periods presented ($ in thousands): December 31, 2018 2017 Change in benefit obligation: Benefit obligation, beginning of year $ 10,102 $ 75,900 Service cost 277 253 Interest cost 332 1,461 Actuarial (gain) loss (827 ) 391 Benefits paid for the Plan (705 ) (68,583 ) Settlement loss — 680 Benefit obligation, end of year $ 9,179 $ 10,102 Change in plan assets: Fair value of plan assets, beginning of year $ 4,596 $ 54,734 Actual return on plan assets (314 ) 481 Employer contributions 377 17,964 Benefit payments for the Plan (705 ) (68,583 ) Fair value of plan assets, end of year $ 3,954 $ 4,596 Funded status at end of year - net liability $ (5,225 ) $ (5,506 ) Amounts recognized in accumulated other comprehensive loss: Net loss - amount recognized $ 2,170 $ 3,187 Years Ended December 31, 2018 2017 2016 Net periodic benefit cost: Service cost $ 277 $ 253 $ 428 Interest cost 332 1,461 3,355 Expected return on plan assets (227 ) (317 ) (2,897 ) Recognized net loss due to defined benefit plan termination — 17,662 — Recognized net loss due to lump sum settlements 161 — 3,906 Recognized net actuarial loss 571 1,414 2,749 Net periodic benefit cost $ 1,114 $ 20,473 $ 7,541 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) $ (1,017 ) $ (18,168 ) $ (3,572 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ 97 $ 2,305 $ 3,969 Weighted-average assumptions as of end of year: Discount rate for benefit obligation 3.97 % 3.32 % 3.71 % Discount rate for net periodic benefit cost 3.32 % 3.71 % 3.86 % Expected long-term return on plan assets 5.00 % 5.00 % 4.25 % Plan Assets The weighted-average asset allocations by asset category are presented below for the Continuing Plan at December 31, 2018 and 2017. No assets remained in the Plan at December 31, 2017. December 31, 2018 2017 Money market fund 8.0 % 6.0 % Exchange traded funds: Equity securities 52.0 % 48.0 % Fixed income 29.0 % 32.0 % International 11.0 % 14.0 % 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, 2018 and 2017 ($ in thousands): 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 $ — $ — December 31, 2017 Total Level 1 Level 2 Level 3 Money market fund $ 269 $ 269 $ — $ — Exchange traded funds: Equity securities 2,199 2,199 — — Fixed income 1,462 1,462 — — International 666 666 — — Total assets at fair value $ 4,596 $ 4,596 $ — $ — There have been no changes in the methodologies used in estimating the fair value of plan assets at December 31, 2018. 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, 2018, Trustmark’s minimum required contribution to the Continuing Plan was $148 thousand; however, Trustmark contributed $275 thousand. For the plan year ending December 31, 2019, Trustmark’s minimum required contribution to the Continuing Plan is expected to be $160 thousand; however, Management and the Board of Directors of Trustmark will monitor the Continuing Plan throughout 2019 to determine any additional funding requirements by the plan’s measurement date. Estimated Future Benefit Payments and Other Disclosures The following table presents the expected benefit payments, which reflect expected future service, for the Continuing Plan ($ in thousands): Year Amount 2019 $ 218 2020 283 2021 382 2022 438 2023 517 2024 - 2028 3,037 Amounts in accumulated other comprehensive loss expected to be recognized as components of net periodic benefit cost during 2019 include a net loss of $371 thousand. Supplemental Retirement Plans Trustmark maintains a nonqualified supplemental retirement plan covering key executive officers and senior officers as well as directors who have elected to defer fees. The plan provides for retirement and/or death benefits based on a participant’s covered salary or deferred fees. Although plan benefits may be paid from Trustmark’s general assets, Trustmark has purchased life insurance contracts on the participants covered under the plan, which may be used to fund future benefit payments under the plan. The measurement date for the plan is December 31. As a result of mergers prior to 2014, Trustmark became the administrator of small nonqualified supplemental retirement plans, for which the plan benefits were frozen prior to the merger date. The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for Trustmark’s nonqualified supplemental retirement plans ($ in thousands): December 31, 2018 2017 Change in benefit obligation: Benefit obligation, beginning of year $ 57,930 $ 58,495 Service cost 116 141 Interest cost 1,865 2,103 Actuarial loss (3,228 ) 642 Benefits paid (3,426 ) (3,451 ) Benefit obligation, end of year $ 53,257 $ 57,930 Change in plan assets: Fair value of plan assets, beginning of year $ — $ — Employer contributions 3,426 3,451 Benefit payments (3,426 ) (3,451 ) Fair value of plan assets, end of year $ — $ — Funded status at end of year - net liability $ (53,257 ) $ (57,930 ) Amounts recognized in accumulated other comprehensive loss: Net loss $ 13,403 $ 17,514 Prior service cost 859 1,109 Amounts recognized $ 14,262 $ 18,623 Years Ended December 31, 2018 2017 2016 Net periodic benefit cost: Service cost $ 116 $ 141 $ 295 Interest cost 1,865 2,103 2,223 Amortization of prior service cost 250 250 250 Recognized net actuarial loss 884 866 864 Net periodic benefit cost $ 3,115 $ 3,360 $ 3,632 Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes: Net (gain) loss $ (4,111 ) $ (224 ) $ (810 ) Amortization of prior service cost (250 ) (250 ) (250 ) Total recognized in other comprehensive income (loss) $ (4,361 ) $ (474 ) $ (1,060 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ (1,246 ) $ 2,886 $ 2,572 Weighted-average assumptions as of end of year: Discount rate for benefit obligation 3.97 % 3.32 % 3.71 % Discount rate for net periodic benefit cost 3.32 % 3.71 % 3.86 % 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 2019 $ 3,534 2020 4,052 2021 4,123 2022 4,291 2023 4,126 2024 - 2028 18,638 Amounts in accumulated other comprehensive loss expected to be recognized as components of net periodic benefit cost during 2019 include a loss of $625 thousand and prior service cost of $250 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 $7.9 million in 2018, $7.5 million in 2017 and $7.2 million in 2016.

Stock and Incentive Compensatio

Stock and Incentive Compensation Plans	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock and Incentive Compensation Plans	Note 16 – 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, 2018, the maximum number of shares of Trustmark’s common stock available for issuance under the Stock Plan was 1,018,337 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, 2018 2017 2016 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 213,516 $ 25.37 237,136 $ 26.27 212,309 $ 24.14 Granted 51,174 31.88 58,406 33.31 99,116 20.18 Released from restriction (55,351 ) 25.32 (67,279 ) 34.78 (40,888 ) 32.84 Forfeited (31,644 ) 26.26 (14,747 ) 28.42 (33,401 ) 30.01 Nonvested shares, end of year 177,695 $ 27.10 213,516 $ 25.37 237,136 $ 26.27 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, 2018 2017 2016 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 320,357 $ 25.40 322,056 $ 22.65 306,657 $ 24.56 Granted 118,325 31.96 105,524 33.79 139,791 20.66 Released from restriction (107,180 ) 23.02 (101,289 ) 25.35 (108,241 ) 23.74 Forfeited (9,632 ) 29.30 (5,934 ) 26.52 (16,151 ) 22.24 Nonvested shares, end of year 321,870 $ 28.48 320,357 $ 25.40 322,056 $ 22.65 The following table presents information regarding compensation expense for awards under the Stock Plan for the periods presented ($ in thousands): At December 31, 2018 Recognized Compensation Expense Unrecognized Weighted Average for Years Ended December 31, Compensation Life of 2018 2017 2016 Expense Compensation Expense Performance awards $ 861 $ 1,387 $ 1,171 $ 1,624 1.64 Time-vested awards 3,009 2,922 2,513 3,548 1.79 Total $ 3,870 $ 4,309 $ 3,684 $ 5,172

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 17 – 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, 2018 and 2017, Trustmark had unused commitments to extend credit of $3.918 billion and $3.172 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, 2018 and 2017, Trustmark’s maximum exposure to credit loss in the event of nonperformance by the other party for letters of credit was $100.2 million and $104.1 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, 2018 and 2017, the fair value of collateral held was $29.8 million and $28.4 million, respectively. Lease Commitments Trustmark currently has operating lease commitments for banking premises and equipment, which expire from 2019 to 2033. It is expected that certain leases will be renewed, or equipment replaced, as leases expire. Rental expense totaled $9.2 million in 2018, $9.3 million in 2017 and $9.8 million in 2016. At December 31, 2018, future minimum rental commitments under non-cancellable operating leases are as follows ($ in thousands): Year Amount 2019 $ 8,680 2020 8,063 2021 7,274 2022 6,680 2023 5,788 Thereafter 29,673 Total $ 66,158 Legal Proceedings Trustmark’s wholly-owned subsidiary, TNB, has been named as a defendant in three lawsuits related to the collapse of the Stanford Financial Group. The first is a purported class action complaint that was filed on August 23, 2009 in the District Court of Harris County, Texas, by Peggy Roif Rotstain, Guthrie Abbott, Catherine Burnell, Steven Queyrouze, Jaime Alexis Arroyo Bornstein and Juan C. Olano (collectively, Class Plaintiffs), on behalf of themselves and all others similarly situated, naming TNB and four other financial institutions unaffiliated with Trustmark as defendants. The complaint seeks to recover (i) alleged fraudulent transfers from each of the defendants in the amount of fees and other monies received by each defendant from entities controlled by R. Allen Stanford (collectively, the Stanford Financial Group) and (ii) damages allegedly attributable to alleged conspiracies by one or more of the defendants with the Stanford Financial Group to commit fraud and/or aid and abet fraud on the asserted grounds that defendants knew or should have known the Stanford Financial Group was conducting an illegal and fraudulent scheme. Plaintiffs have demanded a jury trial. Plaintiffs did not quantify damages. In November 2009, the lawsuit was removed to federal court by certain defendants and then transferred by the United States Panel on Multidistrict Litigation to federal court in the Northern District of Texas (Dallas) where multiple Stanford related matters are being consolidated for pre-trial proceedings. In May 2010, all defendants (including TNB) filed motions to dismiss the lawsuit. In August 2010, the court authorized and approved the formation of an Official Stanford Investors Committee (OSIC) to represent the interests of Stanford investors and, under certain circumstances, to file legal actions for the benefit of Stanford investors. In December 2011, the OSIC filed a motion to intervene in this action. In September 2012, the district court referred the case to a magistrate judge for hearing and determination of certain pretrial issues. In December 2012, the court granted the OSIC’s motion to intervene, and the OSIC filed an Intervenor Complaint against one of the other defendant financial institutions. In February 2013, the OSIC filed a second Intervenor Complaint that asserts claims against TNB and the remaining defendant financial institutions. The OSIC seeks to recover: (i) alleged fraudulent transfers in the amount of the fees each of the defendants allegedly received from Stanford Financial Group, the profits each of the defendants allegedly made from Stanford Financial Group deposits, and other monies each of the defendants allegedly received from Stanford Financial Group; (ii) damages attributable to alleged conspiracies by each of the defendants with the Stanford Financial Group to commit fraud and/or aid and abet fraud and conversion on the asserted grounds that the defendants knew or should have known the Stanford Financial Group was conducting an illegal and fraudulent scheme; and (iii) punitive damages. The OSIC did not quantify damages. In July 2013, all defendants (including TNB) filed motions to dismiss the OSIC’s claims. In March 2015, the court entered an order authorizing the parties to conduct discovery regarding class certification, staying all other discovery and setting a deadline for the parties to complete briefing on class certification issues. In April 2015, the court granted in part and denied in part the defendants’ motions to dismiss the Class Plaintiffs’ claims and the OSIC’s claims. The court dismissed all of the Class Plaintiffs’ fraudulent transfer claims and dismissed certain of the OSIC’s claims. The court denied the motions by TNB and the other financial institution defendants to dismiss the OSIC’s constructive fraudulent transfer claims. On June 23, 2015, the court allowed the Class Plaintiffs to file a Second Amended Class Action Complaint (SAC), which asserted new claims against TNB and certain of the other defendants for (i) aiding, abetting and participating in a fraudulent scheme, (ii) aiding, abetting and participating in violations of the Texas Securities Act, (iii) aiding, abetting and participating in breaches of fiduciary duty, (iv) aiding, abetting and participating in conversion and (v) conspiracy. On July 14, 2015, the defendants (including TNB) filed motions to dismiss the SAC and to reconsider the court’s prior denial to dismiss the OSIC’s constructive fraudulent transfer claims against TNB and the other financial institutions that are defendants in the action. On July 27, 2016, the court denied the motion by TNB and the other financial institution defendants to dismiss the SAC and also denied the motion by TNB and the other financial institution defendants to reconsider the court’s prior denial to dismiss the OSIC’s constructive fraudulent transfer claims. On August 24, 2016, TNB filed its answer to the SAC. On October 20, 2017, the OSIC filed a motion seeking an order lifting the discovery stay and establishing a trial schedule. On November 7, 2017, the court denied the OSIC’s motion seeking class certification and designation of class representatives and counsel, finding that common issues of fact did not predominate. The court granted the OSIC’s motion to lift the discovery stay that it had previously ordered. The second Stanford-related lawsuit was filed on December 14, 2009 in the District Court of Ascension Parish, Louisiana, individually by Harold Jackson, Paul Blaine, Carolyn Bass Smith, Christine Nichols, and Ronald and Ramona Hebert naming TNB (misnamed as Trust National Bank) and other individuals and entities not affiliated with Trustmark as defendants. The complaint seeks to recover the money lost by these individual plaintiffs as a result of the collapse of the Stanford Financial Group (in addition to other damages) under various theories and causes of action, including negligence, breach of contract, breach of fiduciary duty, negligent misrepresentation, detrimental reliance, conspiracy, and violation of Louisiana’s uniform fiduciary, securities, and racketeering laws. The complaint does not quantify the amount of money the plaintiffs seek to recover. In January 2010, the lawsuit was removed to federal court by certain defendants and then transferred by the United States Panel on Multidistrict Litigation to federal court in the Northern District of Texas (Dallas) where multiple Stanford related matters are being consolidated for pre-trial proceedings. On March 29, 2010, the court stayed the case. TNB filed a motion to lift the stay, which was denied on February 28, 2012. In September 2012, the district court referred the case to a magistrate judge for hearing and determination of certain pretrial issues. On April 11, 2016, Trustmark learned that a third Stanford-related lawsuit had been filed on that date in the Superior Court of Justice in Ontario, Canada, by The Toronto-Dominion Bank (“TD Bank”), naming TNB and three other financial institutions not affiliated with Trustmark as defendants. The complaint seeks a declaration specifying the degree to which each of TNB and the other defendants are liable in respect of any loss and damage for which TD Bank is found to be liable in a litigation commenced against TD Bank brought by the Joint Liquidators of Stanford International Bank Limited in the Superior Court of Justice, Commercial List in Ontario, Canada (the “Joint Liquidators’ Action”), as well as contribution and indemnity in respect of any judgment, interest and costs TD Bank is ordered to pay in the Joint Liquidators’ Action. To date, TNB has not been served in connection with this action. TNB’s relationship with the Stanford Financial Group began as a result of Trustmark’s acquisition of a Houston-based bank in August 2006, and consisted of correspondent banking and other traditional banking services in the ordinary course of business. All Stanford-related lawsuits are in pre-trial stages. Trustmark and its subsidiaries are also parties to other lawsuits and other claims that arise in the ordinary course of business. Some of the lawsuits assert claims related to the lending, collection, servicing, investment, trust and other business activities, and some of the lawsuits allege substantial claims for damages. All pending legal proceedings described above are being vigorously contested. In accordance FASB ASC Topic 450-20, “Loss Contingencies,” Trustmark will establish an accrued liability for litigation matters when those matters present loss contingencies that are both probable and reasonably estimable. At the present time, Trustmark believes, based on its evaluation and the advice of legal counsel, that a loss in any such proceeding is not probable and a reasonable estimate cannot reasonably be made.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2018
Stockholders Equity Note [Abstract]
Shareholders' Equity	Note 18 – 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 1.875% at December 31, 2018 and 1.250% at December 31, 2017. 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, 2018, 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, 2018. 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, 2018, which Management believes have affected Trustmark’s or TNB’s present classification. The regulatory capital ratios for December 31, 2017 contain a reclassification adjustment of $8.5 million from accumulated other comprehensive loss to retained earnings as allowed by regulatory agencies in an interagency statement released January 18, 2018 to address disproportionate tax effect in accumulated other comprehensive loss resulting from the recent enactment of the Tax Reform Act and the application of FASB ASC Topic 740. The following table provides Trustmark’s and TNB’s actual regulatory capital amounts and ratios under regulatory capital standards in effect at December 31, 2018 and 2017 ($ in thousands): Actual Regulatory Capital Minimum To Be Well Amount Ratio Requirement Capitalized 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 % At December 31, 2017: Common Equity Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,243,240 11.77 % 5.750 % n/a Trustmark National Bank 1,284,575 12.16 % 5.750 % 6.50 % Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,303,238 12.33 % 7.250 % n/a Trustmark National Bank 1,284,575 12.16 % 7.250 % 8.00 % Total Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,384,050 13.10 % 9.250 % n/a Trustmark National Bank 1,365,387 12.93 % 9.250 % 10.00 % Tier 1 Leverage (to Average Assets) Trustmark Corporation $ 1,303,238 9.67 % 4.00 % n/a Trustmark National Bank 1,284,575 9.54 % 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 2019, TNB will have available approximately $66.0 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 may be acquired through March 31, 2019. The shares may be purchased from time to time at prevailing market prices, through open market or privately negotiated transactions, depending on market conditions. Trustmark repurchased approximately 2.0 million shares of its common stock valued at approximately $62.4 million during the year ended December 31, 2018, compared to no common stock repurchased during the year ended December 31, 2017 and approximately 34 thousand shares of its common stock valued at approximately $750 thousand repurchased during the year ended December 31, 2016. Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss The following tables present the net change in the components of accumulated other comprehensive loss and the related tax effects allocated to each component for the years ended December 31, 2018, 2017 and 2016 ($ 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 15 – 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, 2018 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ (19,221 ) $ 4,805 $ (14,416 ) Reclassification adjustment for net (gains) losses realized in net income — — — 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 Year Ended December 31, 2016 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ (15,656 ) $ 5,989 $ (9,667 ) Reclassification adjustment for net (gains) losses realized in net income 310 (119 ) 191 Change in net unrealized holding loss on securities transferred to held to maturity 9,830 (3,760 ) 6,070 Total securities available for sale and transferred securities (5,516 ) 2,110 (3,406 ) Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans (240 ) 92 (148 ) Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (96 ) 154 Recognized net loss due to lump sum settlements 3,906 (1,494 ) 2,412 Change in net actuarial loss 716 (274 ) 442 Total pension and other postretirement benefit plans 4,632 (1,772 ) 2,860 Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives (369 ) 141 (228 ) Reclassification adjustment for (gain) loss realized in net income 599 (229 ) 370 Total cash flow hedge derivatives 230 (88 ) 142 Total other comprehensive income (loss) $ (654 ) $ 250 $ (404 ) 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, 2016 $ (17,394 ) $ (27,840 ) $ (160 ) $ (45,394 ) Other comprehensive income (loss) before reclassification (3,597 ) (148 ) (228 ) (3,973 ) Amounts reclassified from accumulated other comprehensive loss 191 3,008 370 3,569 Net other comprehensive income (loss) (3,406 ) 2,860 142 (404 ) Balance, December 31, 2016 (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 )

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value	Note 19 – 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, 2018 and 2017, 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, 2018 and 2017. 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 — December 31, 2017 Total Level 1 Level 2 Level 3 U.S. Government agency obligations $ 45,285 $ — $ 45,285 $ — Obligations of states and political subdivisions 79,229 — 79,229 — Mortgage-backed securities 2,114,121 — 2,114,121 — Securities available for sale 2,238,635 — 2,238,635 — Loans held for sale 180,512 — 180,512 — Mortgage servicing rights 84,269 — — 84,269 Other assets - derivatives 1,516 (1,013 ) 1,629 900 Other liabilities - derivatives 2,678 616 2,062 — The changes in Level 3 assets measured at fair value on a recurring basis for the years ended December 31, 2018 and 2017 are summarized as follows ($ in thousands): MSR Other Assets - Derivatives 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 Balance, January 1, 2017 $ 80,239 $ 1,001 Total net (loss) gain included in Mortgage banking, net (1) (11,830 ) 4,165 Additions 15,860 — Sales — (4,266 ) Balance, December 31, 2017 $ 84,269 $ 900 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, 2017 $ (1,050 ) $ (1,569 ) (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, 2018, 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, 2018, Trustmark had outstanding balances of $55.8 million with a related allowance of $6.4 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 $48.9 million with a related allowance of $1.7 million at December 31, 2017. 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 $19.2 million were re-measured during 2018, requiring write-downs of $873 thousand to reach their current fair values compared to $26.6 million of foreclosed assets that were re-measured during 2017, requiring write-downs of $3.3 million. Fair Value of Financial Instruments FASB ASC Topic 825 requires disclosure of the fair value of financial assets and financial liabilities, including those financial assets and financial liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis. The carrying amounts and estimated fair values of financial instruments at December 31, 2018 and 2017 were as follows ($ in thousands): December 31, 2018 December 31, 2017 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Financial Assets: Level 2 Inputs: Cash and short-term investments $ 350,391 $ 350,391 $ 336,383 $ 336,383 Securities held to maturity 909,643 889,733 1,056,486 1,046,247 Level 3 Inputs: Net LHFI 8,756,578 8,757,817 8,493,234 8,507,469 Net acquired loans 105,701 105,701 257,438 257,438 Financial Liabilities: Level 2 Inputs: Deposits 11,364,411 11,365,203 10,577,512 10,577,858 Short-term liabilities 129,477 129,477 1,440,876 1,440,876 Long-term FHLB advances 879 821 946 946 Junior subordinated debt securities 61,856 53,196 61,856 45,773 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, 2018 and 2017, a net gain of $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 compared to a net loss of $2.5 million for the year ended December 31, 2016. Interest and fees on LHFS and LHFI for the years ended December 31, 2018 and 2017 included $4.9 million of interest earned on the LHFS accounted for under the fair value option compared to $5.0 million for the year ended December 31, 2016. 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 $61.6 million and $48.2 million at December 31, 2018 and 2017, respectively, and are included in LHFS on the accompanying consolidated balance sheets. The following table provides information about the fair value and the contractual principal outstanding of the LHFS accounted for under the fair value option as of December 31, 2018 and 2017 ($ in thousands): December 31, 2018 2017 Fair value of LHFS $ 92,235 $ 132,300 LHFS contractual principal outstanding 89,056 129,347 Fair value less unpaid principal $ 3,179 $ 2,953

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Note 20 – 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 beginning December 31, 2014 and ending 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 will pay a fixed interest rate of 1.66% and receive 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, 2018, 2017 and 2016. The accumulated net after-tax gain related to the effective cash flow hedge included in accumulated other comprehensive loss totaled $469 thousand at December 31, 2018 compared to a net after-tax gain of $278 thousand at December 31, 2017. Amounts reported in accumulated other comprehensive loss related to this derivative are reclassified to other interest expense as interest payments are made on Trustmark’s variable rate junior subordinated debentures. During the next twelve months, Trustmark estimates that $625 thousand will be reclassified as a decrease to other interest expense. 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 $318.0 million at December 31, 2018 compared to $349.0 million at December 31, 2017. 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 positive ineffectiveness of $2.4 million for the year ended December 31, 2018, compared to a net positive ineffectiveness of $254 thousand for the year ended December 31, 2017 and a net negative ineffectiveness of $2.9 million for the year ended December 31, 2016. 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 $132.0 million at December 31, 2018, with a negative valuation adjustment of $1.8 million, compared to $182.1 million at December 31, 2017, with a negative valuation adjustment of $237 thousand. 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 $71.2 million at December 31, 2018, with a positive valuation adjustment of $1.2 million, compared to $83.0 million at December 31, 2017, with a positive valuation adjustment of $900 thousand. 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, 2018, Trustmark had interest rate swaps with an aggregate notional amount of $475.8 million related to this program, compared to $351.9 million as of December 31, 2017. 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, 2018 and 2017, 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 $75 thousand and $80 thousand, respectively. As of December 31, 2018, Trustmark had no posted collateral 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, 2018, 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 December 31, 2018, Trustmark had entered into three risk participation agreements as a beneficiary with an aggregate notional amount of $23.1 million compared to two risk participation agreements as a beneficiary with an aggregate notional amount $13.7 million at December 31, 2017. At December 31, 2018, Trustmark had entered into seven risk participation agreements as a guarantor with an aggregate notional amount of $39.0 million compared to six risk participation agreements as a guarantor with an aggregate notional amount of $37.1 million at December 31, 2017. The aggregate fair values of these risk participation agreements were immaterial at December 31, 2018 and 2017. Tabular Disclosures The following tables disclose the fair value of derivative instruments in Trustmark’s consolidated balance sheets as of December 31, 2018 and 2017 as well as the effect of these derivative instruments on Trustmark’s results of operations for the periods presented ($ in thousands): December 31, 2018 2017 Derivatives in hedging relationships Interest rate contracts: Interest rate swaps included in other assets $ 625 $ 451 Derivatives not designated as hedging instruments Interest rate contracts: Futures contracts included in other assets $ 4,445 $ (1,088 ) Exchange traded purchased options included in other assets 561 75 OTC written options (rate locks) included in other assets 1,187 900 Interest rate swaps included in other assets 5,487 1,175 Credit risk participation agreements included in other assets 42 3 Forward contracts included in other liabilities 1,773 237 Exchange traded written options included in other liabilities 66 616 Interest rate swaps included in other liabilities 2,369 1,819 Credit risk participation agreements included in other liabilities 5 6 Years Ended December 31, 2018 2017 2016 Derivatives in hedging relationships Amount of gain (loss) reclassified from accumulated other comprehensive loss and recognized in other interest expense $ 322 $ (282 ) $ (599 ) Derivatives not designated as hedging instruments Amount of gain (loss) recognized in mortgage banking, net $ (6,191 ) $ (1,873 ) $ 13 Amount of gain (loss) recognized in bank card and other fees (357 ) (31 ) 60 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, 2018 2017 2016 Derivatives in cash flow hedging relationship Amount of gain (loss) recognized in other comprehensive income (loss), net of tax $ 373 $ 122 $ (228 ) Information about financial instruments that are eligible for offset in the consolidated balance sheets as of December 31, 2018 and 2017 is presented in the following tables ($ in thousands): Offsetting of Derivative Assets As of December 31, 2018 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 $ 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 Offsetting of Derivative Assets As of December 31, 2017 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 $ 1,626 $ — $ 1,626 $ (311 ) $ — $ 1,315 Offsetting of Derivative Liabilities As of December 31, 2017 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 $ 1,819 $ — $ 1,819 $ (311 ) $ (100 ) $ 1,408

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Information	Note 21 – 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. 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, 2018 2017 2016 General Banking Net interest income $ 418,968 $ 406,406 $ 386,596 Provision for loan losses, net 16,988 7,699 14,714 Noninterest income 114,122 116,180 107,059 Noninterest expense 357,703 373,221 354,555 Income before income taxes 158,399 141,666 124,386 Income taxes 18,885 43,960 25,303 General banking net income $ 139,514 $ 97,706 $ 99,083 Selected Financial Information Total assets $ 13,207,850 $ 13,724,193 $ 13,278,668 Depreciation and amortization $ 38,188 $ 37,710 $ 35,692 Wealth Management Net interest income $ 226 $ 910 $ 726 Noninterest income 30,228 30,285 30,117 Noninterest expense 26,856 27,561 24,165 Income before income taxes 3,598 3,634 6,678 Income taxes 900 1,390 2,554 Wealth Management net income $ 2,698 $ 2,244 $ 4,124 Selected Financial Information Total assets $ 9,691 $ 5,592 $ 7,501 Depreciation and amortization $ 180 $ 131 $ 174 Insurance Net interest income $ 226 $ 234 $ 211 Noninterest income 40,486 38,198 36,767 Noninterest expense 30,856 29,387 28,578 Income before income taxes 9,856 9,045 8,400 Income taxes 2,484 3,365 3,196 Insurance net income $ 7,372 $ 5,680 $ 5,204 Selected Financial Information Total assets $ 68,919 $ 68,168 $ 66,164 Depreciation and amortization $ 572 $ 630 $ 747 Consolidated Net interest income $ 419,420 $ 407,550 $ 387,533 Provision for loan losses, net 16,988 7,699 14,714 Noninterest income 184,836 184,663 173,943 Noninterest expense 415,415 430,169 407,298 Income before income taxes 171,853 154,345 139,464 Income taxes 22,269 48,715 31,053 Consolidated net income $ 149,584 $ 105,630 $ 108,411 Selected Financial Information Total assets $ 13,286,460 $ 13,797,953 $ 13,352,333 Depreciation and amortization $ 38,940 $ 38,471 $ 36,613

Parent Company Only Financial I

Parent Company Only Financial Information	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Parent Company Only Financial Information	Note 22 – Parent Company Only Financial Information ($ in thousands) Condensed Balance Sheets December 31, 2018 2017 Assets: Investment in banks $ 1,637,338 $ 1,617,238 Other assets 16,975 17,349 Total Assets $ 1,654,313 $ 1,634,587 Liabilities and Shareholders' Equity: Accrued expense $ 1,004 $ 1,030 Junior subordinated debt securities 61,856 61,856 Shareholders' equity 1,591,453 1,571,701 Total Liabilities and Shareholders' Equity $ 1,654,313 $ 1,634,587 Condensed Statements of Income Years Ended December 31, 2018 2017 2016 Revenue: Dividends received from banks $ 128,592 $ 65,663 $ 65,987 Earnings of subsidiaries over distributions 23,791 42,211 44,756 Other income 86 71 60 Total Revenue 152,469 107,945 110,803 Expense: Other expense 2,885 2,315 2,392 Total Expense 2,885 2,315 2,392 Net Income $ 149,584 $ 105,630 $ 108,411 Condensed Statements of Cash Flows Years Ended December 31, 2018 2017 2016 Operating Activities: Net income $ 149,584 $ 105,630 $ 108,411 Adjustments to reconcile net income to net cash provided by operating activities: Net change in investment in subsidiaries (23,791 ) (42,211 ) (44,756 ) Other (1,395 ) (1,697 ) (739 ) Net cash from operating activities 124,398 61,722 62,916 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: Cash dividends paid on common stock (62,425 ) (62,795 ) (62,666 ) Other common stock transactions, net (62,421 ) — (857 ) Net cash from financing activities (124,846 ) (62,795 ) (63,523 ) Net change in cash and cash equivalents (448 ) 172 (607 ) Cash and cash equivalents at beginning of year 16,885 16,713 17,320 Cash and cash equivalents at end of year $ 16,437 $ 16,885 $ 16,713 Trustmark (parent company only) paid income taxes of approximately $12.4 million in 2018, $7.4 million in 2017 and $24.8 million in 2016. During 2018, interest received was $320 thousand compared to $283 thousand of interest paid in 2017 and $600 thousand of interest paid during 2016.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
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 196 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 2019 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 Topic 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. If a LHFI that has been specifically reviewed for impairment is deemed impaired, the full difference between the book value and the estimated net realizable value of the collateral is charged off or a specific valuation allowance is established. 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 non-owner 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.
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 Topic 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 Topic 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 Topic 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 Topic 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 Topic 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.
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 Topic 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, 2018 and 2017, Trustmark’s investment in member bank stock totaled $32.2 million and $67.7 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, 2018, 2017 and 2016.
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, 2018 resulted in net gains of $700 thousand compared to $2.1 million for the year ended December 31, 2017 and $7.0 million for the year ended December 31, 2016. 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 Topic 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 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 has 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 period beginning December 31, 2014 and ending December 31, 2019. This derivative instrument is designated as a cash flow hedge under FASB ASC Topic 815. Any accumulated net after-tax gains or losses related to effective cash flow hedge are included in accumulated other comprehensive income (loss), net of tax. Any ineffective portion of the interest rate swap is reclassified from accumulated other comprehensive income (loss), net of tax to noninterest expense in the consolidated statements of income for the relevant periods. Amounts reported in accumulated other comprehensive income (loss), net of tax related to this derivative are reclassified to other interest expense as interest payments are made on Trustmark’s variable rate junior subordinated debentures. 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, 2018 2017 2016 Income taxes paid $ 12,435 $ 7,371 $ 24,836 Interest paid on deposits and borrowings 66,358 41,472 24,312 Noncash transfers from loans to other real estate (1) 12,115 8,760 23,965 Transfer of long-term FHLB advances to short-term — 250,038 500,009 Assets acquired in business combination — 196,265 — Liabilities assumed in business combination — 184,949 — (1) Includes transfers from covered loans to foreclosed properties.
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, 2018 2017 2016 Basic shares 67,505 67,727 67,620 Dilutive shares 154 160 164 Diluted shares 67,659 67,887 67,784 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, 2018 2017 2016 Weighted-average antidilutive stock awards 1 74 2
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 2018-02, “Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.” Issued in February 2018, ASU 2018-02 seeks to help entities reclassify certain stranded income tax effects in accumulated other comprehensive income resulting from the Tax Cuts and Jobs Act of 2017 (Tax Reform Act), enacted on December 22, 2017. ASU 2018-02 was issued in response to concerns regarding current guidance in GAAP that requires deferred tax liabilities and assets to be adjusted for the effect of a change in tax laws or rates with the effect included in income from continuing operations in the reporting period that includes the enactment date, even in situations in which the related income tax effects of items in accumulated other comprehensive income were originally recognized in other comprehensive income, rather than net income, and as a result the stranded tax effects would not reflect the appropriate tax rate. The amendments of ASU 2018-02 allow an entity to make a reclassification from accumulated other comprehensive income to retained earnings for the stranded tax effects, which is the difference between the historical corporate income tax rate of 35.0% and the newly enacted corporate income tax rate of 21.0%. ASU 2018-02 is effective for fiscal years, and interim periods within those years, beginning after December 31, 2018; however, public business entities are allowed to early adopt the amendments of ASU 2018-02 in any interim period for which the financial statements have not yet been issued. The amendments of ASU 2018-02 may be applied either at the beginning of the period (annual or interim) of adoption or retrospectively to each of the period(s) in which the effect of the change in the U.S. federal corporate tax rate in the Tax Reform Act is recognized. As a result of the re-measurement of Trustmark’s deferred tax assets following the enactment of the Tax Reform Act, accumulated other comprehensive loss included $8.5 million of stranded tax effects at December 31, 2017. Trustmark early adopted the amendments of 2018-02 during the first quarter of 2018 and elected to reclassify the stranded tax effects from accumulated other comprehensive loss to retained earnings at the beginning of the period of adoption. The reclassification of the stranded tax effects resulted in an $8.5 million increase in accumulated other comprehensive loss, net of tax and a corresponding increase in retained earnings. ASU 2017-07, “ Compensation-Retirement Benefits (Topic 715)-Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.” Issued in March 2017, ASU 2017-07 is designed to improve guidance related to the presentation of defined benefit costs in the income statement. In particular, ASU No. 2017-07 requires that an employer report the service cost component in the same line item(s) as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. If a separate line item or items are used to present the other components of net benefit cost, then that line item or items must be appropriately described. However, if a separate line item or items are not used, then the line item(s) used in the income statement to present the other components of net benefit cost must be disclosed. Additionally, ASU 2017-07 allows only the service cost component to be eligible for capitalization, when applicable. The amendments of ASU 2017-07 must be applied retrospectively for the presentation of the service cost component and the other components of net periodic benefit cost in the income statement and prospectively, on or after the adoption date, for capitalization of the service cost component in assets. Management evaluated the amendments of this ASU and determined that the amendments of ASU 2017-07 would require a reclassification of the net periodic benefit cost, with the exception of the service cost component, from salaries and employee benefits to other expense on the consolidated statements of income for each period presented, which is not considered material to Trustmark’s consolidated financial statements. Trustmark adopted the amendments of ASU 2017-07 effective January 1, 2018. Trustmark elected the available practical expedient which allows Trustmark to use the amounts disclosed in its pension and other postretirement benefits footnote for the prior comparative periods for applying the retrospective presentation requirements. As a result of the adoption of ASU 2017-07, Trustmark reclassified $3.5 million, $5.7 million and $10.4 million of the net periodic benefit cost from salaries and employee benefits to other expense in the accompanying consolidated statements of income for the years ended December 31, 2018, 2017 and 2016, respectively. ASU 2016-01, “Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (An Amendment of the FASB Accounting Standards Codification).” Issued in January 2016, ASU 2016-01 is intended to enhance the reporting model for financial instruments to provide users of financial statements with improved decision-making information. The amendments of ASU 2016-01 include: (i) requiring equity investments, except those accounted for under the equity method of accounting or those that result in the consolidation of an investee, to be measured at fair value with changes in fair value recognized in net income; (ii) requiring a qualitative assessment to identify impairment of equity investments without readily determinable fair values; (iii) eliminating the requirement to disclose the method and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost on the balance sheet; (iv) requiring the use of the exit price notion when measuring the fair value of financial instruments for disclosure purposes; (v) requiring an entity that has elected the fair value option to measure the fair value of a liability to present separately in other comprehensive income the portion of the change in the fair value resulting from a change in the instrument-specific credit risk; (vi) requiring separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements and (vii) clarifying that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity’s other deferred tax assets. The amendments of ASU 2016-01 became effective for Trustmark on January 1, 2018. Trustmark’s investments in member bank stock, which are equity securities that do not have readily determinable fair values, are not within the scope of ASU 2016-01. See Note 1 – Significant Accounting Policies, “Federal Home Loan Bank (FHLB) and Federal Reserve Bank of Atlanta Stock” for information regarding Trustmark’s investment in member bank stock. Adoption of the amendments of ASU 2016-01 resulted in changes to Trustmark’s fair value related disclosures, specifically amendments (iii) which eliminated the requirement to disclose the method and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost on the balance sheet and (iv) which required the use of the exit price notion when measuring the fair value of the LHFI portfolio. Changes to Trustmark’s fair value related disclosures are presented in Note 19 – Fair Value of this report. The adoption of ASU 2016-01 did not have a material impact on Trustmark’s consolidated financial statements. ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” Issued in May 2014, ASU 2014-09 will add FASB ASC Topic 606, “Revenue from Contracts with Customers,” and will supersede revenue recognition requirements in FASB ASC Topic 605, “Revenue Recognition,” as well as certain cost guidance in FASB ASC Topic 605-35, “Revenue Recognition – Construction-Type and Production-Type Contracts.” ASU 2014-09 provides a framework for revenue recognition that replaces the existing industry and transaction specific requirements under the existing standards. ASU 2014-09 requires an entity to apply a five-step model to determine when to recognize revenue and at what amount. The model specifies that revenue should be recognized when (or as) an entity transfers control of goods or services to a customer at the amount in which the entity expects to be entitled. Depending on whether certain criteria are met, revenue should be recognized either over time, in a manner that depicts the entity’s performance, or at a point in time, when control of the goods or services are transferred to the customer. ASU 2014-09 provides that an entity should apply the following steps: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. In addition, the existing requirements for the recognition of a gain or loss on the transfer of non-financial assets that are not in a contract with a customer are amended to be consistent with the guidance on recognition and measurement in ASU 2014-09. The amendments of ASU 2014-09 may be applied either retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application. If the transition method of application is elected, the entity should also provide the additional disclosures in reporting periods that include the date of initial application of (1) the amount by which each financial statement line item is affected in the current reporting period, as compared to the guidance that was in effect before the change, and (2) an explanation of the reasons for significant changes. The amendments of ASU 2014-09 and all subsequently issued ASUs, which provided additional guidance and clarifications to various aspects of FASB ASC Topic 606, became effective for Trustmark on January 1, 2018. Trustmark elected to adopt these amendments using the modified retrospective method (cumulative effect method) of application for only those contracts not completed as of the date of adoption; therefore, comparative information has not been adjusted and continues to be reported under legacy GAAP. Trustmark’s contracts with customers are primarily for a term of one year or less and substantially all of Trustmark’s contracts were completed as of January 1, 2018. Management determined that approximately 23% of the revenues earned by Trustmark are within the scope of ASU 2014-09, and, for most of the revenue streams within the scope of ASU 2014-09, the amendments do not change the timing or amount of revenue recognized. No cumulative adjustment was recorded as a result of the adoption of ASU 2014-09. Disclosures required by the amendments of ASU 2014-09 are presented in Note 13 – Revenue from Contracts with Customers of this report. The adoption of ASU 2014-09 did not have a material impact on Trustmark’s consolidated financial statements. Changes in Trustmark’s accounting policies as a result of adopting the amendments of ASU 2014-09 included the following: Bank Card and Other Fees Previously, Trustmark recognized interchange fee revenue from point of sale transactions in full as noninterest income in bank card and other fees and recorded a separate expense as noninterest expense in other expense for the amounts payable to the payment network. Under the guidelines of FASB ASC Topic 606, Trustmark records the amounts payable to the payment network for point of sale transactions as noninterest income in bank card and other fees and, therefore, reports revenue from interchange fee contracts net of the consideration for which Trustmark is not entitled. Insurance Commissions Commissions subject to clawback provisions are considered variable consideration subject to variable constraint under FASB ASC Topic 606. Previously, FBBI recognized revenue from insurance contracts in full when the commissions were invoiced or received and recorded a negative commission amount at the time the commissions were paid back to the insurance provider as a result of a policy cancellation or lapse. No allowance for doubtful accounts was previously recorded related to the commission revenue subject to clawback provisions. As a result of the adoption of FASB ASC Topic 606, 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 estimated returned commissions amount (contra-revenue) and a corresponding liability is recorded in other liabilities. 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 commissions percentage is updated annually. Wealth Management A portion of the revenue received by Trustmark from investment services and trust tax contracts are payable to third-parties for related services rendered and represents consideration for which Trustmark is not entitled under FASB ASC Topic 606. Previously, Trustmark recognized revenue from investment services and trust tax contracts in full as noninterest income in wealth management and recorded a separate expense for services rendered related to these contracts as noninterest expense in other expense. Under FASB ASC Topic 606, Trustmark records expenses for services rendered related to these contracts as noninterest income in wealth management (contra-revenue) and, as a result, revenue from wealth management contracts is reported net of the amount for which Trustmark is not entitled. Pending Accounting Pronouncements 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 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Trustmark does not currently have any material amount of implementation costs related to hosting arrangements that are service contracts and is not expected to have a material impact to Trustmark’s consolidated financial statements; however, Management will continue to evaluate the impact of this ASU on future hosting arrangements as well as Trustmark’s consolidated financial statements through its effective date. 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 are effective for fiscal years, and interim periods within those years, beginning after December 15, 2019. Trustmark plans to adopt ASU 2018-13 during the first quarter of 2020. Management is currently assessing all the potential impacts of the amendments in ASU 2018-13 on Trustmark’s consolidated financial statements; however, the adoption of ASU 2018-13 is not expected to have a material impact on Trustmark’s 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. As of December 31, 2018, Trustmark’s total unamortized premium for purchased debt securities within the scope of ASU 2017-08 was immaterial. The adoption of ASU 2017-08 did not have to have a material impact on Trustmark’s consolidated financial statements. ASU 2017-04, “ Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” Issued in January 2017, ASU 2017-04 simplifies the manner in which an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit's goodwill with the carrying amount of that goodwill. In computing the implied fair value of goodwill under Step 2, an entity, prior to the amendments in ASU 2017-04, had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities, including unrecognized assets and liabilities, in accordance with the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. However, under the amendments in ASU 2017-04, an entity should (1) perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, and (2) recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value, with the understanding that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, ASU 2017-04 removes the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails such qualitative test, to perform Step 2 of the goodwill impairment test. ASU 2017-04 is effective prospectively for annual, or any interim, goodwill impairment tests in fiscal years beginning after December 15, 2019. Based on Trustmark’s annual goodwill impairment test performed as of October 1, 2018, the fair value of its reporting units exceeded the carrying value and, therefore, the related goodwill was not impaired. Management will continue to evaluate the impact this ASU will have on Trustmark’s consolidated financial statements through its effective date; however, the adoption of ASU 2017-04 is not expected to have a material impact 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 are effective for interim and annual periods beginning after December 15, 2019. Earlier application is permitted for interim and annual periods beginning after December 15, 2018. Trustmark has established a Current Expected Credit Loss (CECL) Steering Committee, a CECL Solution Development Working Group and a CECL Working Group which include the appropriate members of Management to evaluate the impact this ASU will have on Trustmark’s financial position, results of operations and financial statement disclosures and determine the most appropriate method of implementing the amendments in this ASU as well as any resources needed to implement the amendments. Trustmark intends to adopt the amendments of ASU 2016-13 during the first quarter of 2020. 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 develop the CECL model and evaluate the impact to Trustmark. Trustmark is working with the third-party vendor on using various modeling techniques to develop its methodology. Trustmark is on schedule to fully comply with all CECL requirements within its internally established timeframe for implementation. Management will continue to evaluate the impact this ASU will have on Trustmark’s consolidated financial statements through its effective date. ASU 2016-02, “Leases (Topic 842).” Issued in February 2016, ASU 2016-02 was issued by the FASB to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and by disclosing key information about leasing arrangements. ASU 2016-02 will, among other things, require lessees to recognize a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. ASU 2016-02 does not significantly change lease accounting requirements applicable to lessors; however, the ASU contains some targeted improvements that are intended to align, where necessary, lessor accounting with the lessee accounting model and with the updated revenue recognition guidance issued in 2014. At adoption, Trustmark will recognize a lease asset and a corresponding lease liability on its consolidated balance sheet for its total lease obligation measured on a discounted basis. 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. Based on Management’s evaluation, Trustmark does not expect the amendments of ASU 2016-02 to have any 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 have been 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. Management is currently finalizing the evaluation of Trustmark’s lease obligations as potential lease assets and liabilities as defined by ASU 2016-02; however, the adoption of ASU 2016-02 is not expected to have a material impact on Trustmark’s consolidated financial statements. Based on Management’s preliminary analysis of Trustmark’s existing lease contracts, it is estimated that the adoption of ASU 2016-02 will result in a less than 0.5% increase in assets and liabilities on Trustmark’s consolidated balance sheets. Disclosures required by the amendments of ASU 2016-02 will be presented beginning with the Qu

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 2017 2016 Income taxes paid $ 12,435 $ 7,371 $ 24,836 Interest paid on deposits and borrowings 66,358 41,472 24,312 Noncash transfers from loans to other real estate (1) 12,115 8,760 23,965 Transfer of long-term FHLB advances to short-term — 250,038 500,009 Assets acquired in business combination — 196,265 — Liabilities assumed in business combination — 184,949 — (1) Includes transfers from covered loans to foreclosed properties.
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, 2018 2017 2016 Basic shares 67,505 67,727 67,620 Dilutive shares 154 160 164 Diluted shares 67,659 67,887 67,784
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, 2018 2017 2016 Weighted-average antidilutive stock awards 1 74 2

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018
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, 2018 and 2017 ($ 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, 2018 Cost Gains Losses Value Cost Gains Losses Value 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 December 31, 2017 U.S. Government agency obligations $ 45,763 $ 322 $ (800 ) $ 45,285 $ 3,692 $ 182 $ — $ 3,874 Obligations of states and political subdivisions 78,433 850 (54 ) 79,229 46,039 1,044 (59 ) 47,024 Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 66,634 215 (1,103 ) 65,746 13,539 207 (73 ) 13,673 Issued by FNMA and FHLMC 824,872 827 (11,249 ) 814,450 133,975 210 (1,559 ) 132,626 Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 1,028,176 1,808 (13,194 ) 1,016,790 678,926 1,209 (11,065 ) 669,070 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 218,252 426 (1,543 ) 217,135 180,315 1,102 (1,437 ) 179,980 Total $ 2,262,130 $ 4,448 $ (27,943 ) $ 2,238,635 $ 1,056,486 $ 3,954 $ (14,193 ) $ 1,046,247
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, 2018 and 2017 ($ in thousands): Less than 12 Months 12 Months or More Total Gross Gross Gross Estimated Unrealized Estimated Unrealized Estimated Unrealized December 31, 2018 Fair Value Losses Fair Value Losses Fair Value Losses 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 ) December 31, 2017 U.S. Government agency obligations $ 5,214 $ (113 ) $ 29,432 $ (687 ) $ 34,646 $ (800 ) Obligations of states and political subdivisions 19,345 (80 ) 3,874 (33 ) 23,219 (113 ) Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 37,304 (351 ) 29,446 (825 ) 66,750 (1,176 ) Issued by FNMA and FHLMC 506,410 (4,219 ) 369,060 (8,589 ) 875,470 (12,808 ) Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 755,013 (7,668 ) 534,955 (16,591 ) 1,289,968 (24,259 ) Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 230,898 (1,719 ) 55,288 (1,261 ) 286,186 (2,980 ) Total $ 1,554,184 $ (14,150 ) $ 1,022,055 $ (27,986 ) $ 2,576,239 $ (42,136 )
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 2018 2017 2016 Proceeds from calls and sales of securities $ — $ 27,682 $ 24,693 Gross realized gains — 16 32 Gross realized losses — (1 ) (342 )
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, 2018, 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 $ 24,449 $ 24,475 $ 170 $ 170 Due after one year through five years 27,271 27,481 35,073 35,193 Due after five years through ten years 3,056 2,989 4,276 4,350 Due after ten years 26,962 26,066 — — 81,738 81,011 39,519 39,713 Mortgage-backed securities 1,772,791 1,730,802 870,124 850,020 Total $ 1,854,529 $ 1,811,813 $ 909,643 $ 889,733

LHFI and Allowance for Loan L_2

LHFI and Allowance for Loan Losses, LHFI (Tables)	12 Months Ended
	Dec. 31, 2018
Accounts Notes Loans And Financing Receivable Gross Allowance And Net [Abstract]
Loan Portfolio Held for Investment	At December 31, 2018 and 2017, LHFI consisted of the following ($ in thousands): December 31, 2018 2017 Loans secured by real estate: Construction, land development and other land $ 1,056,601 $ 987,624 Secured by 1-4 family residential properties 1,825,492 1,675,311 Secured by nonfarm, nonresidential properties 2,220,914 2,193,823 Other real estate secured 543,820 517,956 Commercial and industrial loans 1,538,715 1,570,345 Consumer loans 182,448 171,918 State and other political subdivision loans 973,818 952,483 Other loans 494,060 500,507 LHFI 8,835,868 8,569,967 Less allowance for loan losses, LHFI 79,290 76,733 Net LHFI $ 8,756,578 $ 8,493,234
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, 2018 and 2017 ($ in thousands): 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. December 31, 2017 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 $ 391 $ 1 $ — $ 392 $ 2,105 $ 985,127 $ 987,624 Secured by 1-4 family residential properties 6,412 2,084 1,917 10,413 19,022 1,645,876 1,675,311 Secured by nonfarm, nonresidential properties 2,319 256 — 2,575 12,608 2,178,640 2,193,823 Other real estate secured — — — — 212 517,744 517,956 Commercial and industrial loans 759 1,233 12 2,004 33,338 1,535,003 1,570,345 Consumer loans 2,141 255 242 2,638 135 169,145 171,918 State and other political subdivision loans 350 39 — 389 — 952,094 952,483 Other loans 18 4 — 22 155 500,330 500,507 Total $ 12,390 $ 3,872 $ 2,171 $ 18,433 $ 67,575 $ 8,483,959 $ 8,569,967 (1) Past due 90 days or more but still accruing interest.
Impaired Financing Receivables	At December 31, 2018 and 2017, individually evaluated for impaired LHFI consisted of the following ($ in thousands): 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 December 31, 2017 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 $ 1,704 $ 1,206 $ 199 $ 1,405 $ 75 $ 1,923 Secured by 1-4 family residential properties 6,031 160 4,576 4,736 1,331 4,693 Secured by nonfarm, nonresidential properties 15,205 10,027 396 10,423 165 8,321 Other real estate secured — — — — — — Commercial and industrial loans 36,874 31,281 518 31,799 131 22,734 Consumer loans 17 — 17 17 — 9 State and other political subdivision loans — — — — — — Other loans 556 — 556 556 41 325 Total $ 60,387 $ 42,674 $ 6,262 $ 48,936 $ 1,743 $ 38,005
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, 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 Year Ended December 31, 2016 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 $ 14 $ 14 Secured by 1-4 family residential properties 18 1,386 1,391 Secured by nonfarm, nonresidential properties 2 717 717 Commercial and industrial loans 5 10,043 9,982 Consumer loans 1 2 2 Total 27 $ 12,162 $ 12,106
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 period ($ in thousands): Years Ended December 31, 2018 2017 2016 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 5 734 4 78 1 — Commercial and industrial loans 6 15,178 3 9,526 2 2,154 Consumer loans 1 1 — — — — Total 13 $ 15,935 7 $ 9,604 3 $ 2,154
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, 2018, 2017 and 2016 ($ in thousands): 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 December 31, 2016 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 405 $ 405 Secured by 1-4 family residential properties — 2,873 2,873 Secured by nonfarm, nonresidential properties — 881 881 Commercial and industrial loans 53 10,266 10,319 Consumer loans — 2 2 Total TDRs $ 53 $ 14,427 $ 14,480
Carrying Amount of Loans by Credit Quality Indicator	The tables below present LHFI by loan type and credit quality indicator at December 31, 2018 and 2017 ($ in thousands): December 31, 2018 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 $ 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 Days or More 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 December 31, 2017 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 $ 922,563 $ 316 $ 3,780 $ 222 $ 926,881 Secured by 1-4 family residential properties 127,405 134 4,948 76 132,563 Secured by nonfarm, nonresidential properties 2,135,749 6,684 50,785 527 2,193,745 Other real estate secured 517,036 — 517 — 517,553 Commercial and industrial loans 1,437,590 28,780 103,089 886 1,570,345 Consumer loans — — — — — State and other political subdivision loans 936,420 5,850 10,213 — 952,483 Other loans 478,083 — 16,390 108 494,581 Total $ 6,554,846 $ 41,764 $ 189,722 $ 1,819 $ 6,788,151 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 $ 60,240 $ 342 $ — $ 161 $ 60,743 $ 987,624 Secured by 1-4 family residential properties 1,516,691 7,874 1,809 16,374 1,542,748 1,675,311 Secured by nonfarm, nonresidential properties 78 — — — 78 2,193,823 Other real estate secured 403 — — — 403 517,956 Commercial and industrial loans — — — — — 1,570,345 Consumer loans 169,146 2,396 242 134 171,918 171,918 State and other political subdivision loans — — — — — 952,483 Other loans 5,926 — — — 5,926 500,507 Total $ 1,752,484 $ 10,612 $ 2,051 $ 16,669 $ 1,781,816 $ 8,569,967
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, 2018 and 2017 ($ in thousands): 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 December 31, 2017 Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ 75 $ 7,790 $ 7,865 Secured by 1-4 family residential properties 1,331 9,543 10,874 Secured by nonfarm, nonresidential properties 165 23,263 23,428 Other real estate secured — 2,790 2,790 Commercial and industrial loans 131 22,720 22,851 Consumer loans — 3,470 3,470 State and other political subdivision loans — 789 789 Other loans 41 4,625 4,666 Total allowance for loan losses, LHFI $ 1,743 $ 74,990 $ 76,733 Changes in the allowance for loan losses, LHFI were as follows for the periods presented ($ in thousands): Years Ended December 31, 2018 2017 2016 Balance at beginning of period $ 76,733 $ 71,265 $ 67,619 Transfers (1) 1,554 — — Loans charged-off (29,489 ) (21,147 ) (18,930 ) Recoveries 12,499 11,521 11,619 Net (charge-offs) recoveries (16,990 ) (9,626 ) (7,311 ) Provision for loan losses, LHFI 17,993 15,094 10,957 Balance at end of period $ 79,290 $ 76,733 $ 71,265 (1) The allowance for loan losses balance related to the remaining loans acquired in the Heritage acquisition on April 15, 2011, the Bay Bank merger on March 16, 2012 and the Reliance merger on April 7, 2017, 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, 2018 and 2017, respectively ($ in thousands): 2018 Balance Provision for Balance January 1, Transfers (1) Charge-offs Recoveries Loan Losses December 31, 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 (1) The allowance for loan losses balance related to the remaining loans acquired in the Heritage acquisition on April 15, 2011, the Bay Bank merger on March 16, 2012 and the Reliance merger on April 7, 2017, which were transferred from acquired impaired loans to LHFI during 2018. 2017 Balance Provision for Balance January 1, Charge-offs Recoveries Loan Losses December 31, Loans secured by real estate: Construction, land development and other land $ 9,085 $ (79 ) $ 1,428 $ (2,569 ) $ 7,865 Secured by 1-4 family residential properties 10,347 (950 ) 1,833 (356 ) 10,874 Secured by nonfarm, nonresidential properties 20,967 (4,231 ) 396 6,296 23,428 Other real estate secured 2,263 (5 ) 69 463 2,790 Commercial and industrial loans 22,011 (8,286 ) 2,578 6,548 22,851 Consumer loans 3,241 (2,546 ) 1,938 837 3,470 State and other political subdivision loans 859 — — (70 ) 789 Other loans 2,492 (5,050 ) 3,279 3,945 4,666 Total allowance for loan losses, LHFI $ 71,265 $ (21,147 ) $ 11,521 $ 15,094 $ 76,733
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, 2018 and 2017 ($ in thousands): 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 December 31, 2017 LHFI Evaluated for Impairment Individually Collectively Total Loans secured by real estate: Construction, land development and other land $ 1,405 $ 986,219 $ 987,624 Secured by 1-4 family residential properties 4,736 1,670,575 1,675,311 Secured by nonfarm, nonresidential properties 10,423 2,183,400 2,193,823 Other real estate secured — 517,956 517,956 Commercial and industrial loans 31,799 1,538,546 1,570,345 Consumer loans 17 171,901 171,918 State and other political subdivision loans — 952,483 952,483 Other loans 556 499,951 500,507 Total $ 48,936 $ 8,521,031 $ 8,569,967

Acquired Loans (Tables)

Acquired Loans (Tables)	12 Months Ended
	Dec. 31, 2018
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities [Abstract]
Schedule of Acquired Loans	At December 31, 2018 and 2017, acquired loans consisted of the following ($ in thousands): December 31, 2018 2017 Loans secured by real estate: Construction, land development and other land $ 5,878 $ 23,586 Secured by 1-4 family residential properties 22,556 61,751 Secured by nonfarm, nonresidential properties 47,979 114,694 Other real estate secured 8,253 16,746 Commercial and industrial loans 15,267 31,506 Consumer loans 1,356 2,600 Other loans 5,643 10,634 Acquired loans 106,932 261,517 Less allowance for loan losses, acquired loans 1,231 4,079 Net acquired loans $ 105,701 $ 257,438
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, 2017 $ 218,107 $ 42,743 Transfers (2) — (36,719 ) Additions (3) 7,899 109,548 Accretion to interest income 14,924 1,578 Payments received, net (68,317 ) (39,208 ) Other (4) (361 ) (74 ) Change in allowance for loan losses, acquired loans 7,318 — Carrying value, net at December 31, 2017 179,570 77,868 Transfers (5)(2) (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 (1) “Acquired Not ASC 310-30” loans consist of loans that are not in scope for FASB ASC Topic 310-30. (2) “Acquired Not ASC 310-30” loans transferred to LHFI due to the discount on these loans being fully amortized. (3) Loans acquired in the Reliance merger on April 7, 2017. (4) Includes miscellaneous timing adjustments as well as acquired loan terminations through foreclosure, charge-off and other terminations. (5) During 2018, Trustmark transferred the remaining loans acquired in the Heritage acquisition on April 11, 2015, the Bay Bank merger on March 16, 2012 and the Reliance merger on April 7, 2017 from acquired impaired loans to LHFI.
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, 2018 2017 2016 Accretable yield at beginning of period $ (31,426 ) $ (38,918 ) $ (52,672 ) Additions due to acquisition (1) — (784 ) — Accretion to interest income 9,514 14,924 18,405 Disposals, net 3,926 2,868 6,488 Transfers (2) 5,874 — — Reclassification from nonaccretable difference (3) (5,610 ) (9,516 ) (11,139 ) Accretable yield at end of period $ (17,722 ) $ (31,426 ) $ (38,918 ) (1) Accretable yield on loans acquired from Reliance on April 7, 2017. (2) During 2018, Trustmark transferred the remaining loans acquired in the Heritage acquisition on April 11, 2015, the Bay Bank merger on March 16, 2012 and the Reliance merger on April 7, 2017 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, 2018 2017 2016 Balance at beginning of period $ 4,079 $ 11,397 $ 11,992 Transfers (1) (1,554 ) — — Provision for loan losses, acquired loans (1,005 ) (7,395 ) 3,757 Net (charge-offs) recoveries (289 ) 77 (4,352 ) Balance at end of period $ 1,231 $ 4,079 $ 11,397 (1) The allowance for loan losses balance related to the remaining loans acquired in the Heritage acquisition, the Bay Bank merger and the Reliance merger, 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, 2018 and 2017 ($ in thousands): 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 Topic 310-30. December 31, 2017 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 $ 17,150 $ 234 $ 4,690 $ 264 $ 22,338 Secured by 1-4 family residential properties 14,021 298 3,029 — 17,348 Secured by nonfarm, nonresidential properties 95,147 1,400 17,583 530 114,660 Other real estate secured 12,730 102 3,031 477 16,340 Commercial and industrial loans 22,157 15 7,585 1,749 31,506 Consumer loans — — — — — Other loans 5,874 18 4,742 — 10,634 Total acquired loans $ 167,079 $ 2,067 $ 40,660 $ 3,020 $ 212,826 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 $ 1,188 $ 46 $ 14 $ — $ 1,248 $ 23,586 Secured by 1-4 family residential properties 42,008 1,687 584 124 44,403 61,751 Secured by nonfarm, nonresidential properties 34 — — — 34 114,694 Other real estate secured 406 — — — 406 16,746 Commercial and industrial loans — — — — — 31,506 Consumer loans 2,428 172 — — 2,600 2,600 Other loans — — — — — 10,634 Total acquired loans $ 46,064 $ 1,905 $ 598 $ 124 $ 48,691 $ 261,517 (1) Acquired loans not accounted for under FASB ASC Topic 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, 2018 and 2017 ($ in thousands): 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 Topic 310-30. December 31, 2017 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 $ 34 $ 90 $ 861 $ 985 $ — $ 22,601 $ 23,586 Secured by 1-4 family residential properties 1,691 614 654 2,959 302 58,490 61,751 Secured by nonfarm, nonresidential properties 467 73 898 1,438 — 113,256 114,694 Other real estate secured 132 — — 132 — 16,614 16,746 Commercial and industrial loans — — — — 2 31,504 31,506 Consumer loans 16 156 — 172 — 2,428 2,600 Other loans — — 21 21 — 10,613 10,634 Total acquired loans $ 2,340 $ 933 $ 2,434 $ 5,707 $ 304 $ 255,506 $ 261,517 (1) Past due 90 days or more but still accruing interest. (2) Acquired loans not accounted for under FASB ASC Topic 310-30.

Premises and Equipment, Net (Ta

Premises and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Premises and Equipment	At December 31, 2018 and 2017, premises and equipment consisted of the following ($ in thousands): December 31, 2018 2017 Land $ 52,779 $ 52,335 Buildings and leasehold improvements 202,912 197,372 Furniture and equipment 169,652 166,071 Total cost of premises and equipment 425,343 415,778 Less accumulated depreciation and amortization 247,160 237,425 Premises and equipment, net 178,183 178,353 Assets held for sale 485 986 Total premises and equipment, net $ 178,668 $ 179,339

Mortgage Banking (Tables)

Mortgage Banking (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 2017 Balance at beginning of period $ 84,269 $ 80,239 Origination of servicing assets 15,759 15,860 Change in fair value: Due to market changes 7,342 (1,050 ) Due to runoff (11,774 ) (10,780 ) Balance at end of period $ 95,596 $ 84,269
Schedule of Mortgage Loans Sold and Serviced for Others	The table below details the mortgage loans sold and serviced for others at December 31, 2018 and 2017 ($ in thousands): December 31, 2018 2017 Federal National Mortgage Association $ 4,204,336 $ 4,128,614 Government National Mortgage Association 2,537,238 2,421,456 Federal Home Loan Mortgage Corporation 71,343 47,071 Other 21,957 26,864 Total mortgage loans sold and serviced for others $ 6,834,874 $ 6,624,005
Changes In The Reserve For Mortgage Loan Servicing Putback Expense	Changes in the reserve for mortgage loan servicing putback expense for mortgage loans were as follows for the periods presented ($ in thousands): Years Ended December 31, 2018 2017 2016 Balance at beginning of period $ 1,000 $ 1,130 $ 1,685 Provision for putback expenses — (836 ) 420 Other (1) — 706 (975 ) Balance at end of period $ 1,000 $ 1,000 $ 1,130 (1) Includes fair value adjustments for loans transferred due to underwriting issues as well as adjustments based on Trustmark’s mortgage loan servicing putback reserve analysis.

Goodwill and Identifiable Int_2

Goodwill and Identifiable Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill by segment	The table below illustrates goodwill by segment for the years ended December 31, 2018 and 2017 ($ in thousands): General Banking Insurance Total Balance as of January 1, 2017 $ 321,132 $ 45,024 $ 366,156 Goodwill from Reliance merger during 2017 13,471 — 13,471 Balance as of December 31, 2017 334,603 45,024 379,627 Adjustment during 2018 — — — Balance as of December 31, 2018 $ 334,603 $ 45,024 $ 379,627
Schedule of identifiable intangible assets	At December 31, 2018 and 2017, identifiable intangible assets consisted of the following ($ in thousands): December 31, 2018 December 31, 2017 Gross Accumulated Net Carrying Gross Carrying Accumulated Net Carrying Amount Amortization Amount Amount Amortization Amount Core deposit intangibles $ 87,674 $ 78,353 $ 9,321 $ 87,674 $ 73,494 $ 14,180 Insurance intangibles 13,824 12,348 1,476 13,824 12,026 1,798 Banking charters 1,325 1,010 315 1,325 943 382 Borrower relationship intangible — — — 690 690 — Total $ 102,823 $ 91,711 $ 11,112 $ 103,513 $ 87,153 $ 16,360 The following table illustrates the carrying amounts and remaining weighted-average amortization periods of identifiable intangible assets as of December 31, 2018 ($ in thousands): Remaining Weighted- Average Net Carrying Amortization Amount Period in Core deposit intangibles $ 9,321 4.4 Insurance intangibles 1,476 15.5 Banking charters 315 4.7 Total $ 11,112 5.9

Other Real Estate (Tables)

Other Real Estate (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 2017 2016 (1) Balance at beginning of period $ 43,228 $ 62,051 $ 78,828 Additions (2) 12,115 9,235 24,525 Disposals (19,802 ) (24,762 ) (36,801 ) Write-downs (873 ) (3,296 ) (4,501 ) Balance at end of period $ 34,668 $ 43,228 $ 62,051 Gain (losses), net on the sale of other real estate included in other real estate expense $ 700 $ 2,087 $ 7,031 (1) The changes and gains, net on other real estate for the year ended December 31, 2016 include covered other real estate. (2) For the year ended December 31, 2017, additions to other real estate included $475 thousand of other real estate acquired in the Reliance merger on April 7, 2017.
Other Real Estate, By Type of Property	At December 31, 2018 and 2017, other real estate by type of property consisted of the following ($ in thousands): December 31, 2018 2017 Construction, land development and other land properties $ 16,206 $ 27,491 1-4 family residential properties 4,983 5,081 Nonfarm, nonresidential properties 13,296 10,468 Other real estate properties 183 188 Total other real estate $ 34,668 $ 43,228
Other Real Estate, By Geographic Location	At December 31, 2018 and 2017, other real estate by geographic location consisted of the following ($ in thousands): December 31, 2018 2017 Alabama $ 6,873 $ 11,714 Florida 8,771 13,937 Mississippi (1) 17,255 14,260 Tennessee (2) 1,025 2,535 Texas 744 782 Total other real estate $ 34,668 $ 43,228 (1) Mississippi includes Central and Southern Mississippi Regions. (2) Tennessee includes Memphis, Tennessee and Northern Mississippi Regions.

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2018
Deposits [Abstract]
Deposits Summary	At December 31, 2018 and 2017, deposits consisted of the following ($ in thousands): December 2018 2017 Noninterest-bearing demand $ 2,937,594 $ 2,978,074 Interest-bearing demand 2,633,259 2,432,814 Savings 3,905,659 3,408,183 Time 1,887,899 1,758,441 Total $ 11,364,411 $ 10,577,512
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, 2018 2017 2016 Interest-bearing demand $ 18,479 $ 6,820 $ 3,297 Savings 17,980 6,047 2,657 Time 17,477 9,850 6,794 Total $ 53,936 $ 22,717 $ 12,748
Maturities of Interest-Bearing Deposits	The maturities of interest-bearing deposits at December 31, 2018, are as follows ($ in thousands): 2019 $ 1,478,845 2020 295,596 2021 55,927 2022 33,616 2023 and thereafter 23,915 Total time deposits 1,887,899 Interest-bearing deposits with no stated maturity 6,538,918 Total interest-bearing deposits $ 8,426,817

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 ($ in thousands): December 31, 2018 2017 Mortgage-backed securities Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA $ 6,721 $ 68,246 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 38,788 50,448 Total securities sold under repurchase agreements $ 45,509 $ 118,694
Summary of Short-Term Borrowings	At December 31, 2018 and 2017, short-term borrowings consisted of the following ($ in thousands): December 2018 2017 FHLB advances $ — $ 900,013 Serviced GNMA loans eligible for repurchase 61,564 48,211 Other 17,442 22,825 Total short-term borrowings $ 79,006 $ 971,049

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 Year Ended December 31, 2017 (1) Year Ended December 31, 2016 (1) Topic 606 Not Topic 606 (2) Total Topic 606 Not Topic 606 (2) Total Topic 606 Not Topic 606 (2) Total General Banking Segment Service charges on deposit accounts $ 43,699 $ — $ 43,699 $ 44,001 $ — $ 44,001 $ 45,252 $ — $ 45,252 Bank card and other fees 26,926 1,897 28,823 27,979 250 28,229 27,230 663 27,893 Mortgage banking, net — 34,674 34,674 — 29,902 29,902 — 28,212 28,212 Wealth management 296 — 296 210 — 210 566 — 566 Other, net 6,826 (196 ) 6,630 6,565 7,258 13,823 7,185 (1,739 ) 5,446 Security gains (losses), net — — — — 15 15 — (310 ) (310 ) Total noninterest income $ 77,747 $ 36,375 $ 114,122 $ 78,755 $ 37,425 $ 116,180 $ 80,233 $ 26,826 $ 107,059 Wealth Management Segment Service charges on deposit accounts $ 3 $ — $ 3 $ 2 $ — $ 2 $ 1 $ — $ 1 Bank card and other fees 82 — 82 57 — 57 13 — 13 Wealth management 30,042 — 30,042 30,130 — 30,130 29,926 — 29,926 Other, net 4 97 101 1 95 96 83 94 177 Total noninterest income $ 30,131 $ 97 $ 30,228 $ 30,190 $ 95 $ 30,285 $ 30,023 $ 94 $ 30,117 Insurance Segment Insurance commissions $ 40,481 $ — $ 40,481 $ 38,168 $ — $ 38,168 $ 36,764 $ — $ 36,764 Other, net 5 — 5 30 — 30 3 — 3 Total noninterest income $ 40,486 $ — $ 40,486 $ 38,198 $ — $ 38,198 $ 36,767 $ — $ 36,767 Consolidated Service charges on deposit accounts $ 43,702 $ — $ 43,702 $ 44,003 $ — $ 44,003 $ 45,253 $ — $ 45,253 Bank card and other fees 27,008 1,897 28,905 28,036 250 28,286 27,243 663 27,906 Mortgage banking, net — 34,674 34,674 — 29,902 29,902 — 28,212 28,212 Insurance commissions 40,481 — 40,481 38,168 — 38,168 36,764 — 36,764 Wealth management 30,338 — 30,338 30,340 — 30,340 30,492 — 30,492 Other, net 6,835 (99 ) 6,736 6,596 7,353 13,949 7,271 (1,645 ) 5,626 Security gains (losses), net — — — — 15 15 — (310 ) (310 ) Total noninterest income $ 148,364 $ 36,472 $ 184,836 $ 147,143 $ 37,520 $ 184,663 $ 147,023 $ 26,920 $ 173,943 (1) 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. (2) 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, 2018
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, 2018 2017 2016 Current Federal $ 4,532 $ 16,959 $ 10,355 State 5,997 5,687 2,698 Deferred Federal 9,392 7,280 15,647 State 2,348 1,820 2,353 Income tax provision excluding deferred tax asset revaluation and reversal of valuation allowance 22,269 31,746 31,053 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 $ 22,269 $ 48,715 $ 31,053
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, 2018 2017 2016 Income tax computed at statutory tax rate $ 36,089 $ 54,021 $ 48,812 Tax exempt interest (4,533 ) (7,611 ) (6,780 ) Nondeductible interest expense 416 407 201 State income taxes, net 4,738 3,697 1,754 Income tax credits, net (15,404 ) (15,793 ) (16,183 ) Death benefit gains (268 ) (3,268 ) — Reversal of valuation allowance — (8,650 ) — Re-measurement of deferred tax assets — 25,619 — Other 1,231 293 3,249 Income tax provision $ 22,269 $ 48,715 $ 31,053
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, 2018 and 2017, which are included in other assets on the accompanying consolidated balance sheets ($ in thousands): December 31, 2018 2017 Deferred tax assets: Loan purchase accounting $ 1,564 $ 3,638 Other real estate 7,284 13,403 Allowance for loan losses 20,638 20,203 Deferred compensation 15,607 15,184 Realized built-in losses 12,182 12,932 Securities 3,929 4,869 Pension and other postretirement benefit plans 4,108 5,453 Interest on nonaccrual loans 806 774 Unrealized losses on securities available for sale 10,679 5,874 Stock-based compensation 2,192 2,067 Federal carryovers 1,606 4,569 Other 9,179 8,964 Gross deferred tax asset 89,774 97,930 Deferred tax liabilities: Goodwill and other identifiable intangibles 16,229 16,729 Premises and equipment 12,109 11,877 Mortgage servicing rights 14,415 9,964 Securities 1,519 1,345 Other 5,600 5,040 Gross deferred tax liability 49,872 44,955 Net deferred tax asset $ 39,902 $ 52,975
Changes in Unrecognized Tax Benefits	The following table provides a summary of the changes during the 2018 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, 2018 $ 1,105 Change due to tax positions taken during the current year 282 Change due to tax positions taken during a prior year 56 Change due to the lapse of applicable statute of limitations during the current year (194 ) Change due to settlements with taxing authorities during the current year — Balance at December 31, 2018 $ 1,249 Accrued interest, net of federal benefit, at December 31, 2018 $ 212 Unrecognized tax benefits that would impact the effective tax rate, if recognized, at December 31, 2018 $ 988

Defined Benefit and Other Pos_2

Defined Benefit and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2018
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 Trustmark’s tax-qualified defined benefit pension plans (the Continuing Plan and the Plan) for the periods presented ($ in thousands): December 31, 2018 2017 Change in benefit obligation: Benefit obligation, beginning of year $ 10,102 $ 75,900 Service cost 277 253 Interest cost 332 1,461 Actuarial (gain) loss (827 ) 391 Benefits paid for the Plan (705 ) (68,583 ) Settlement loss — 680 Benefit obligation, end of year $ 9,179 $ 10,102 Change in plan assets: Fair value of plan assets, beginning of year $ 4,596 $ 54,734 Actual return on plan assets (314 ) 481 Employer contributions 377 17,964 Benefit payments for the Plan (705 ) (68,583 ) Fair value of plan assets, end of year $ 3,954 $ 4,596 Funded status at end of year - net liability $ (5,225 ) $ (5,506 ) Amounts recognized in accumulated other comprehensive loss: Net loss - amount recognized $ 2,170 $ 3,187
Net Periodic Benefit Cost	Years Ended December 31, 2018 2017 2016 Net periodic benefit cost: Service cost $ 277 $ 253 $ 428 Interest cost 332 1,461 3,355 Expected return on plan assets (227 ) (317 ) (2,897 ) Recognized net loss due to defined benefit plan termination — 17,662 — Recognized net loss due to lump sum settlements 161 — 3,906 Recognized net actuarial loss 571 1,414 2,749 Net periodic benefit cost $ 1,114 $ 20,473 $ 7,541 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) $ (1,017 ) $ (18,168 ) $ (3,572 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ 97 $ 2,305 $ 3,969 Weighted-average assumptions as of end of year: Discount rate for benefit obligation 3.97 % 3.32 % 3.71 % Discount rate for net periodic benefit cost 3.32 % 3.71 % 3.86 % Expected long-term return on plan assets 5.00 % 5.00 % 4.25 %
Weighted-Average Asset Allocation	The weighted-average asset allocations by asset category are presented below for the Continuing Plan at December 31, 2018 and 2017. No assets remained in the Plan at December 31, 2017. December 31, 2018 2017 Money market fund 8.0 % 6.0 % Exchange traded funds: Equity securities 52.0 % 48.0 % Fixed income 29.0 % 32.0 % International 11.0 % 14.0 % 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, 2018 and 2017 ($ in thousands): 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 $ — $ — December 31, 2017 Total Level 1 Level 2 Level 3 Money market fund $ 269 $ 269 $ — $ — Exchange traded funds: Equity securities 2,199 2,199 — — Fixed income 1,462 1,462 — — International 666 666 — — Total assets at fair value $ 4,596 $ 4,596 $ — $ —
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 2019 $ 218 2020 283 2021 382 2022 438 2023 517 2024 - 2028 3,037
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 ($ in thousands): December 31, 2018 2017 Change in benefit obligation: Benefit obligation, beginning of year $ 57,930 $ 58,495 Service cost 116 141 Interest cost 1,865 2,103 Actuarial loss (3,228 ) 642 Benefits paid (3,426 ) (3,451 ) Benefit obligation, end of year $ 53,257 $ 57,930 Change in plan assets: Fair value of plan assets, beginning of year $ — $ — Employer contributions 3,426 3,451 Benefit payments (3,426 ) (3,451 ) Fair value of plan assets, end of year $ — $ — Funded status at end of year - net liability $ (53,257 ) $ (57,930 ) Amounts recognized in accumulated other comprehensive loss: Net loss $ 13,403 $ 17,514 Prior service cost 859 1,109 Amounts recognized $ 14,262 $ 18,623
Net Periodic Benefit Cost	Years Ended December 31, 2018 2017 2016 Net periodic benefit cost: Service cost $ 116 $ 141 $ 295 Interest cost 1,865 2,103 2,223 Amortization of prior service cost 250 250 250 Recognized net actuarial loss 884 866 864 Net periodic benefit cost $ 3,115 $ 3,360 $ 3,632 Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes: Net (gain) loss $ (4,111 ) $ (224 ) $ (810 ) Amortization of prior service cost (250 ) (250 ) (250 ) Total recognized in other comprehensive income (loss) $ (4,361 ) $ (474 ) $ (1,060 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ (1,246 ) $ 2,886 $ 2,572 Weighted-average assumptions as of end of year: Discount rate for benefit obligation 3.97 % 3.32 % 3.71 % Discount rate for net periodic benefit cost 3.32 % 3.71 % 3.86 %
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 2019 $ 3,534 2020 4,052 2021 4,123 2022 4,291 2023 4,126 2024 - 2028 18,638

Stock and Incentive Compensat_2

Stock and Incentive Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 2017 2016 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 213,516 $ 25.37 237,136 $ 26.27 212,309 $ 24.14 Granted 51,174 31.88 58,406 33.31 99,116 20.18 Released from restriction (55,351 ) 25.32 (67,279 ) 34.78 (40,888 ) 32.84 Forfeited (31,644 ) 26.26 (14,747 ) 28.42 (33,401 ) 30.01 Nonvested shares, end of year 177,695 $ 27.10 213,516 $ 25.37 237,136 $ 26.27 The following table summarizes Trustmark’s time-vested award activity for the periods presented: Years Ended December 31, 2018 2017 2016 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 320,357 $ 25.40 322,056 $ 22.65 306,657 $ 24.56 Granted 118,325 31.96 105,524 33.79 139,791 20.66 Released from restriction (107,180 ) 23.02 (101,289 ) 25.35 (108,241 ) 23.74 Forfeited (9,632 ) 29.30 (5,934 ) 26.52 (16,151 ) 22.24 Nonvested shares, end of year 321,870 $ 28.48 320,357 $ 25.40 322,056 $ 22.65
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, 2018 Recognized Compensation Expense Unrecognized Weighted Average for Years Ended December 31, Compensation Life of 2018 2017 2016 Expense Compensation Expense Performance awards $ 861 $ 1,387 $ 1,171 $ 1,624 1.64 Time-vested awards 3,009 2,922 2,513 3,548 1.79 Total $ 3,870 $ 4,309 $ 3,684 $ 5,172

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Rental Commitments Under Non-cancellable Operating Leases	At December 31, 2018, future minimum rental commitments under non-cancellable operating leases are as follows ($ in thousands): Year Amount 2019 $ 8,680 2020 8,063 2021 7,274 2022 6,680 2023 5,788 Thereafter 29,673 Total $ 66,158

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 ($ in thousands): Actual Regulatory Capital Minimum To Be Well Amount Ratio Requirement Capitalized 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 % At December 31, 2017: Common Equity Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,243,240 11.77 % 5.750 % n/a Trustmark National Bank 1,284,575 12.16 % 5.750 % 6.50 % Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,303,238 12.33 % 7.250 % n/a Trustmark National Bank 1,284,575 12.16 % 7.250 % 8.00 % Total Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,384,050 13.10 % 9.250 % n/a Trustmark National Bank 1,365,387 12.93 % 9.250 % 10.00 % Tier 1 Leverage (to Average Assets) Trustmark Corporation $ 1,303,238 9.67 % 4.00 % n/a Trustmark National Bank 1,284,575 9.54 % 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, 2018 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ (19,221 ) $ 4,805 $ (14,416 ) Reclassification adjustment for net (gains) losses realized in net income — — — 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 Year Ended December 31, 2016 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ (15,656 ) $ 5,989 $ (9,667 ) Reclassification adjustment for net (gains) losses realized in net income 310 (119 ) 191 Change in net unrealized holding loss on securities transferred to held to maturity 9,830 (3,760 ) 6,070 Total securities available for sale and transferred securities (5,516 ) 2,110 (3,406 ) Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans (240 ) 92 (148 ) Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (96 ) 154 Recognized net loss due to lump sum settlements 3,906 (1,494 ) 2,412 Change in net actuarial loss 716 (274 ) 442 Total pension and other postretirement benefit plans 4,632 (1,772 ) 2,860 Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives (369 ) 141 (228 ) Reclassification adjustment for (gain) loss realized in net income 599 (229 ) 370 Total cash flow hedge derivatives 230 (88 ) 142 Total other comprehensive income (loss) $ (654 ) $ 250 $ (404 )
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, 2016 $ (17,394 ) $ (27,840 ) $ (160 ) $ (45,394 ) Other comprehensive income (loss) before reclassification (3,597 ) (148 ) (228 ) (3,973 ) Amounts reclassified from accumulated other comprehensive loss 191 3,008 370 3,569 Net other comprehensive income (loss) (3,406 ) 2,860 142 (404 ) Balance, December 31, 2016 (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 )

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017, 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, 2018 and 2017. 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 — December 31, 2017 Total Level 1 Level 2 Level 3 U.S. Government agency obligations $ 45,285 $ — $ 45,285 $ — Obligations of states and political subdivisions 79,229 — 79,229 — Mortgage-backed securities 2,114,121 — 2,114,121 — Securities available for sale 2,238,635 — 2,238,635 — Loans held for sale 180,512 — 180,512 — Mortgage servicing rights 84,269 — — 84,269 Other assets - derivatives 1,516 (1,013 ) 1,629 900 Other liabilities - derivatives 2,678 616 2,062 —
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, 2018 and 2017 are summarized as follows ($ in thousands): MSR Other Assets - Derivatives 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 Balance, January 1, 2017 $ 80,239 $ 1,001 Total net (loss) gain included in Mortgage banking, net (1) (11,830 ) 4,165 Additions 15,860 — Sales — (4,266 ) Balance, December 31, 2017 $ 84,269 $ 900 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, 2017 $ (1,050 ) $ (1,569 ) (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, 2018 and 2017 were as follows ($ in thousands): December 31, 2018 December 31, 2017 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Financial Assets: Level 2 Inputs: Cash and short-term investments $ 350,391 $ 350,391 $ 336,383 $ 336,383 Securities held to maturity 909,643 889,733 1,056,486 1,046,247 Level 3 Inputs: Net LHFI 8,756,578 8,757,817 8,493,234 8,507,469 Net acquired loans 105,701 105,701 257,438 257,438 Financial Liabilities: Level 2 Inputs: Deposits 11,364,411 11,365,203 10,577,512 10,577,858 Short-term liabilities 129,477 129,477 1,440,876 1,440,876 Long-term FHLB advances 879 821 946 946 Junior subordinated debt securities 61,856 53,196 61,856 45,773
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, 2018 and 2017 ($ in thousands): December 31, 2018 2017 Fair value of LHFS $ 92,235 $ 132,300 LHFS contractual principal outstanding 89,056 129,347 Fair value less unpaid principal $ 3,179 $ 2,953

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 as well as the effect of these derivative instruments on Trustmark’s results of operations for the periods presented ($ in thousands): December 31, 2018 2017 Derivatives in hedging relationships Interest rate contracts: Interest rate swaps included in other assets $ 625 $ 451 Derivatives not designated as hedging instruments Interest rate contracts: Futures contracts included in other assets $ 4,445 $ (1,088 ) Exchange traded purchased options included in other assets 561 75 OTC written options (rate locks) included in other assets 1,187 900 Interest rate swaps included in other assets 5,487 1,175 Credit risk participation agreements included in other assets 42 3 Forward contracts included in other liabilities 1,773 237 Exchange traded written options included in other liabilities 66 616 Interest rate swaps included in other liabilities 2,369 1,819 Credit risk participation agreements included in other liabilities 5 6
Effects of Derivative Instruments on Statements of Operations	Years Ended December 31, 2018 2017 2016 Derivatives in hedging relationships Amount of gain (loss) reclassified from accumulated other comprehensive loss and recognized in other interest expense $ 322 $ (282 ) $ (599 ) Derivatives not designated as hedging instruments Amount of gain (loss) recognized in mortgage banking, net $ (6,191 ) $ (1,873 ) $ 13 Amount of gain (loss) recognized in bank card and other fees (357 ) (31 ) 60
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, 2018 2017 2016 Derivatives in cash flow hedging relationship Amount of gain (loss) recognized in other comprehensive income (loss), net of tax $ 373 $ 122 $ (228 )
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, 2018 and 2017 is presented in the following tables ($ in thousands): Offsetting of Derivative Assets As of December 31, 2018 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 $ 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 Offsetting of Derivative Assets As of December 31, 2017 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 $ 1,626 $ — $ 1,626 $ (311 ) $ — $ 1,315 Offsetting of Derivative Liabilities As of December 31, 2017 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 $ 1,819 $ — $ 1,819 $ (311 ) $ (100 ) $ 1,408

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 2017 2016 General Banking Net interest income $ 418,968 $ 406,406 $ 386,596 Provision for loan losses, net 16,988 7,699 14,714 Noninterest income 114,122 116,180 107,059 Noninterest expense 357,703 373,221 354,555 Income before income taxes 158,399 141,666 124,386 Income taxes 18,885 43,960 25,303 General banking net income $ 139,514 $ 97,706 $ 99,083 Selected Financial Information Total assets $ 13,207,850 $ 13,724,193 $ 13,278,668 Depreciation and amortization $ 38,188 $ 37,710 $ 35,692 Wealth Management Net interest income $ 226 $ 910 $ 726 Noninterest income 30,228 30,285 30,117 Noninterest expense 26,856 27,561 24,165 Income before income taxes 3,598 3,634 6,678 Income taxes 900 1,390 2,554 Wealth Management net income $ 2,698 $ 2,244 $ 4,124 Selected Financial Information Total assets $ 9,691 $ 5,592 $ 7,501 Depreciation and amortization $ 180 $ 131 $ 174 Insurance Net interest income $ 226 $ 234 $ 211 Noninterest income 40,486 38,198 36,767 Noninterest expense 30,856 29,387 28,578 Income before income taxes 9,856 9,045 8,400 Income taxes 2,484 3,365 3,196 Insurance net income $ 7,372 $ 5,680 $ 5,204 Selected Financial Information Total assets $ 68,919 $ 68,168 $ 66,164 Depreciation and amortization $ 572 $ 630 $ 747 Consolidated Net interest income $ 419,420 $ 407,550 $ 387,533 Provision for loan losses, net 16,988 7,699 14,714 Noninterest income 184,836 184,663 173,943 Noninterest expense 415,415 430,169 407,298 Income before income taxes 171,853 154,345 139,464 Income taxes 22,269 48,715 31,053 Consolidated net income $ 149,584 $ 105,630 $ 108,411 Selected Financial Information Total assets $ 13,286,460 $ 13,797,953 $ 13,352,333 Depreciation and amortization $ 38,940 $ 38,471 $ 36,613

Parent Company Only Financial_2

Parent Company Only Financial Information (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Parent Only Financial Statements	Condensed Balance Sheets December 31, 2018 2017 Assets: Investment in banks $ 1,637,338 $ 1,617,238 Other assets 16,975 17,349 Total Assets $ 1,654,313 $ 1,634,587 Liabilities and Shareholders' Equity: Accrued expense $ 1,004 $ 1,030 Junior subordinated debt securities 61,856 61,856 Shareholders' equity 1,591,453 1,571,701 Total Liabilities and Shareholders' Equity $ 1,654,313 $ 1,634,587 Condensed Statements of Income Years Ended December 31, 2018 2017 2016 Revenue: Dividends received from banks $ 128,592 $ 65,663 $ 65,987 Earnings of subsidiaries over distributions 23,791 42,211 44,756 Other income 86 71 60 Total Revenue 152,469 107,945 110,803 Expense: Other expense 2,885 2,315 2,392 Total Expense 2,885 2,315 2,392 Net Income $ 149,584 $ 105,630 $ 108,411 Condensed Statements of Cash Flows Years Ended December 31, 2018 2017 2016 Operating Activities: Net income $ 149,584 $ 105,630 $ 108,411 Adjustments to reconcile net income to net cash provided by operating activities: Net change in investment in subsidiaries (23,791 ) (42,211 ) (44,756 ) Other (1,395 ) (1,697 ) (739 ) Net cash from operating activities 124,398 61,722 62,916 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: Cash dividends paid on common stock (62,425 ) (62,795 ) (62,666 ) Other common stock transactions, net (62,421 ) — (857 ) Net cash from financing activities (124,846 ) (62,795 ) (63,523 ) Net change in cash and cash equivalents (448 ) 172 (607 ) Cash and cash equivalents at beginning of year 16,885 16,713 17,320 Cash and cash equivalents at end of year $ 16,437 $ 16,885 $ 16,713

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)OfficeFactorRegionFeeRevenueCategoryContract	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of offices | Office		196
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		$ 32,200,000	$ 67,700,000
Number of types of interchange fees | Fee		2
Other real estate sales, net gains		$ 700,000	$ 2,087,000	$ 7,031,000	[1]
Number of trust management revenue categories | RevenueCategory		5
Time period between service obligation completed and payment received from trust customer		30 days
Number of general categories of insurance contracts | Contract		4
Corporate income tax rate		21.00%	35.00%
Stranded tax effects, reclassify from accumulated other comprehensive loss to retained earnings	$ 8,500,000		$ 8,500,000
Accounting Standard Update 2017-07 [Member]
Summary Of Significant Accounting Policies [Line Items]
Net periodic benefit cost		$ 3,500,000	$ 5,700,000	$ 10,400,000
Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative adjustment		$ 0
Percentage of revenues earned		23.00%
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
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] | Personal Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period		30 days
Minimum [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] | Personal Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period		60 days
Maximum [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
[1]	The changes and gains, net on other real estate for the year ended December 31, 2016 include covered other real estate.

Significant Accounting Polici_5

Significant Accounting Policies - Additional Information (Details 1) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01	Dec. 31, 2018
Personal Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenue recognition contract term	1 year
Employee Benefits Insurance Contracts [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, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of cash flows specific transaction amounts [Abstract]
Income taxes paid		$ 12,435	$ 7,371	$ 24,836
Interest paid on deposits and borrowings		66,358	41,472	24,312
Noncash transfers from loans to other real estate	[1]	$ 12,115	8,760	23,965
Transfer of long-term FHLB advances to short-term			250,038	$ 500,009
Assets acquired in business combination			196,265
Liabilities assumed in business combination			$ 184,949
[1]	Includes transfers from covered loans to foreclosed properties.

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share (EPS) [Abstract]
Basic shares	67,505	67,727	67,620
Dilutive shares	154	160	164
Diluted shares	67,659	67,887	67,784

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	Dec. 31, 2016
Accounting Policies [Abstract]
Weighted-average antidilutive stock awards (in shares)	1	74	2

Business Combinations - Additio

Business Combinations - Additional Information (Details) $ / shares in Units, $ in Thousands	Apr. 07, 2017USD ($)Office	Jun. 30, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Nov. 14, 2016$ / shares
Business Acquisition [Line Items]
Goodwill			$ 379,627	$ 379,627	$ 366,156
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			$ 13,500
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, 2018	Dec. 31, 2017	Apr. 07, 2017	Dec. 31, 2016
Liabilities:
Goodwill	$ 379,627	$ 379,627		$ 366,156
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		$ 13,500	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, 2018	Dec. 31, 2017
Cash And Cash Equivalents [Abstract]
Average reserve balances with Federal Reserve Bank	$ 112.4	$ 100.8

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, 2018	Dec. 31, 2017
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	$ 1,854,529	$ 2,262,130
Securities Available for Sale, Gross Unrealized Gains	841	4,448
Securities Available for Sale, Gross Unrealized (Losses)	(43,557)	(27,943)
Securities Available for Sale, Estimated Fair Value	1,811,813	2,238,635
Securities Held to Maturity, Amortized Cost	909,643	1,056,486
Securities Held to Maturity, Gross Unrealized Gains	909	3,954
Securities Held to Maturity, Gross Unrealized (Losses)	(20,819)	(14,193)
Securities Held to Maturity, Estimated Fair Value	889,733	1,046,247
U.S. Government Agency Obligations [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	31,235	45,763
Securities Available for Sale, Gross Unrealized Gains	109	322
Securities Available for Sale, Gross Unrealized (Losses)	(1,009)	(800)
Securities Available for Sale, Estimated Fair Value	30,335	45,285
Securities Held to Maturity, Amortized Cost	3,736	3,692
Securities Held to Maturity, Gross Unrealized Gains	78	182
Securities Held to Maturity, Gross Unrealized (Losses)	0	0
Securities Held to Maturity, Estimated Fair Value	3,814	3,874
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	50,503	78,433
Securities Available for Sale, Gross Unrealized Gains	200	850
Securities Available for Sale, Gross Unrealized (Losses)	(27)	(54)
Securities Available for Sale, Estimated Fair Value	50,676	79,229
Securities Held to Maturity, Amortized Cost	35,783	46,039
Securities Held to Maturity, Gross Unrealized Gains	255	1,044
Securities Held to Maturity, Gross Unrealized (Losses)	(139)	(59)
Securities Held to Maturity, Estimated Fair Value	35,899	47,024
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	69,648	66,634
Securities Available for Sale, Gross Unrealized Gains	147	215
Securities Available for Sale, Gross Unrealized (Losses)	(2,301)	(1,103)
Securities Available for Sale, Estimated Fair Value	67,494	65,746
Securities Held to Maturity, Amortized Cost	12,090	13,539
Securities Held to Maturity, Gross Unrealized Gains	45	207
Securities Held to Maturity, Gross Unrealized (Losses)	(257)	(73)
Securities Held to Maturity, Estimated Fair Value	11,878	13,673
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	685,520	824,872
Securities Available for Sale, Gross Unrealized Gains	127	827
Securities Available for Sale, Gross Unrealized (Losses)	(18,963)	(11,249)
Securities Available for Sale, Estimated Fair Value	666,684	814,450
Securities Held to Maturity, Amortized Cost	115,133	133,975
Securities Held to Maturity, Gross Unrealized Gains	43	210
Securities Held to Maturity, Gross Unrealized (Losses)	(2,887)	(1,559)
Securities Held to Maturity, Estimated Fair Value	112,289	132,626
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	830,129	1,028,176
Securities Available for Sale, Gross Unrealized Gains	67	1,808
Securities Available for Sale, Gross Unrealized (Losses)	(18,595)	(13,194)
Securities Available for Sale, Estimated Fair Value	811,601	1,016,790
Securities Held to Maturity, Amortized Cost	578,827	678,926
Securities Held to Maturity, Gross Unrealized Gains	189	1,209
Securities Held to Maturity, Gross Unrealized (Losses)	(15,441)	(11,065)
Securities Held to Maturity, Estimated Fair Value	563,575	669,070
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	187,494	218,252
Securities Available for Sale, Gross Unrealized Gains	191	426
Securities Available for Sale, Gross Unrealized (Losses)	(2,662)	(1,543)
Securities Available for Sale, Estimated Fair Value	185,023	217,135
Securities Held to Maturity, Amortized Cost	164,074	180,315
Securities Held to Maturity, Gross Unrealized Gains	299	1,102
Securities Held to Maturity, Gross Unrealized (Losses)	(2,095)	(1,437)
Securities Held to Maturity, Estimated Fair Value	$ 162,278	$ 179,980

Securities Available for Sale_4

Securities Available for Sale and Held to Maturity - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	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	$ 15,700,000	$ 19,500,000
Net unamortized, unrealized loss on transfer of securities, net of tax	11,800,000	12,000,000
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	2,144,000,000	1,834,000,000
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, 2018	Dec. 31, 2017
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	$ 98,188	$ 1,554,184
Estimated Fair Value, 12 Months or More	2,399,747	1,022,055
Estimated Fair Value, Total	2,497,935	2,576,239
Gross Unrealized (Losses), Less than 12 Months	(382)	(14,150)
Gross Unrealized (Losses), 12 Months or More	(63,994)	(27,986)
Gross Unrealized (Losses), Total	(64,376)	(42,136)
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	0	5,214
Estimated Fair Value, 12 Months or More	25,045	29,432
Estimated Fair Value, Total	25,045	34,646
Gross Unrealized (Losses), Less than 12 Months		(113)
Gross Unrealized (Losses), 12 Months or More	(1,009)	(687)
Gross Unrealized (Losses), Total	(1,009)	(800)
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	4,954	19,345
Estimated Fair Value, 12 Months or More	12,802	3,874
Estimated Fair Value, Total	17,756	23,219
Gross Unrealized (Losses), Less than 12 Months	(9)	(80)
Gross Unrealized (Losses), 12 Months or More	(157)	(33)
Gross Unrealized (Losses), Total	(166)	(113)
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	9,163	37,304
Estimated Fair Value, 12 Months or More	61,141	29,446
Estimated Fair Value, Total	70,304	66,750
Gross Unrealized (Losses), Less than 12 Months	(54)	(351)
Gross Unrealized (Losses), 12 Months or More	(2,504)	(825)
Gross Unrealized (Losses), Total	(2,558)	(1,176)
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	31,931	506,410
Estimated Fair Value, 12 Months or More	731,749	369,060
Estimated Fair Value, Total	763,680	875,470
Gross Unrealized (Losses), Less than 12 Months	(172)	(4,219)
Gross Unrealized (Losses), 12 Months or More	(21,678)	(8,589)
Gross Unrealized (Losses), Total	(21,850)	(12,808)
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	46,643	755,013
Estimated Fair Value, 12 Months or More	1,296,221	534,955
Estimated Fair Value, Total	1,342,864	1,289,968
Gross Unrealized (Losses), Less than 12 Months	(110)	(7,668)
Gross Unrealized (Losses), 12 Months or More	(33,926)	(16,591)
Gross Unrealized (Losses), Total	(34,036)	(24,259)
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	5,497	230,898
Estimated Fair Value, 12 Months or More	272,789	55,288
Estimated Fair Value, Total	278,286	286,186
Gross Unrealized (Losses), Less than 12 Months	(37)	(1,719)
Gross Unrealized (Losses), 12 Months or More	(4,720)	(1,261)
Gross Unrealized (Losses), Total	$ (4,757)	$ (2,980)

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Gains (losses) on Investments [Abstract]
Proceeds from calls and sales of securities	$ 0	$ 27,682	$ 24,693
Gross realized gains	0	16	32
Gross realized losses	$ 0	$ (1)	$ (342)

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, 2018	Dec. 31, 2017
Securities Available for Sale, Amortized Cost [Abstract]
Due in one year or less	$ 24,449
Due after one year through five years	27,271
Due after five years through ten years	3,056
Due after ten years	26,962
Total amortized cost, before mortgage-backed securities	81,738
Mortgage-backed securities	1,772,791
Securities Available for Sale, Amortized Cost	1,854,529	$ 2,262,130
Securities Available for Sale, Estimated Fair Value [Abstract]
Due in one year or less	24,475
Due after one year through five years	27,481
Due after five years through ten years	2,989
Due after ten years	26,066
Total fair value, before mortgage-backed securities	81,011
Mortgage-backed securities	1,730,802
Total	1,811,813	2,238,635
Securities Held to Maturity, Amortized Cost [Abstract]
Due in one year or less	170
Due after one year through five years	35,073
Due after five years through ten years	4,276
Due after ten years	0
Total amortized cost, before mortgage-backed securities	39,519
Mortgage-backed securities	870,124
Securities Held to Maturity, Amortized Cost	909,643	1,056,486
Securities Held to Maturity, Estimated Fair Value [Abstract]
Due in one year or less	170
Due after one year through five years	35,193
Due after five years through ten years	4,350
Due after ten years	0
Total fair value, before mortgage-backed securities	39,713
Mortgage-backed securities	850,020
Total	$ 889,733	$ 1,046,247

LHFI and Allowance for Loan L_3

LHFI and Allowance for Loan Losses, LHFI - Loan Portfolio Held for Investment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loan Portfolio [Abstract]
Total LHFI	$ 8,835,868	$ 8,569,967
Less allowance for loan losses, LHFI	79,290	76,733
Net LHFI	8,756,578	8,493,234
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	1,056,601	987,624
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	1,825,492	1,675,311
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	543,820	517,956
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	2,220,914	2,193,823
Commercial and Industrial Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	1,538,715	1,570,345
Consumer Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	182,448	171,918
State and Other Political Subdivision Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	973,818	952,483
Other Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	$ 494,060	$ 500,507

LHFI and Allowance for Loan L_4

LHFI and Allowance for Loan Losses, LHFI - Additional Information (Details 1) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)Region	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Financing Receivable Impaired [Line Items]
Maximum concentration of loan as a percentage of total LHFI	10.00%
Key market regions | Region	5
Loans and Leases Receivable, Related Parties	$ 49,000	$ 59,900
New loan advances to related party	440,500
Loan repayment by related party	451,400
Loan increase (decreases) from changes in executive officers and directors	0
Carrying amounts of nonaccrual LHFI considered for impairment analysis	61,600	67,600
Nonaccrual	61,624	67,575
Minimum loan amount for loan to be specifically reviewed for impairment and deemed impaired	500
LHFI Classified as TDRs	28,200	23,900	$ 14,500
LHFI classified as TDRs from credits with interest only payments	23,800	20,500	9,800
Unused Commitments on TDRs	4,400
Financing receivable, related allowance	2,300	458	2,200
Financing receivable, related charge-offs	18,400	127	1,000
Troubled Debt Restructurings [Member]
Financing Receivable Impaired [Line Items]
Nonaccrual	$ 16,706	$ 23,211	$ 14,427

LHFI and Allowance for Loan L_5

LHFI and Allowance for Loan Losses, LHFI - Aging Analysis of Past Due and Nonaccrual LHFI by Loan Type (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		$ 17,691	$ 18,433
Nonaccrual		61,624	67,575
Current Loans		8,756,553	8,483,959
Total LHFI		8,835,868	8,569,967
Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		14,383	12,390
Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		2,452	3,872
Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	[1]	856	2,171
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		284	392
Nonaccrual		2,218	2,105
Current Loans		1,054,099	985,127
Total LHFI		1,056,601	987,624
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		284	391
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			1
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		10,869	10,413
Nonaccrual		14,718	19,022
Current Loans		1,799,905	1,645,876
Total LHFI		1,825,492	1,675,311
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		8,600	6,412
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		1,700	2,084
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]	569	1,917
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		1,887	2,575
Nonaccrual		9,621	12,608
Current Loans		2,209,406	2,178,640
Total LHFI		2,220,914	2,193,823
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		1,887	2,319
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due			256
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		296
Nonaccrual		927	212
Current Loans		542,597	517,744
Total LHFI		543,820	517,956
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		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		1,646	2,004
Nonaccrual		23,938	33,338
Current Loans		1,513,131	1,535,003
Total LHFI		1,538,715	1,570,345
Commercial and Industrial Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		1,346	759
Commercial and Industrial Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		300	1,233
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	[1]		12
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		2,440	2,638
Nonaccrual		205	135
Current Loans		179,803	169,145
Total LHFI		182,448	171,918
Consumer Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		1,800	2,141
Consumer Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		353	255
Consumer Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	[1]	287	242
State and Other Political Subdivision Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		186	389
Nonaccrual		8,595
Current Loans		965,037	952,094
Total LHFI		973,818	952,483
State and Other Political Subdivision Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		186	350
State and Other Political Subdivision Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due			39
Other Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		83	22
Nonaccrual		1,402	155
Current Loans		492,575	500,330
Total LHFI		494,060	500,507
Other Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		$ 83	18
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.

LHFI and Allowance for Loan L_6

LHFI and Allowance for Loan Losses, LHFI - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	$ 62,921	$ 60,387
Total LHFI With No Related Allowance Recorded	25,553	42,674
Total LHFI With an Allowance Recorded	30,282	6,262
Total LHFI Carrying Amount	55,835	48,936
Related Allowance	6,354	1,743
Average Recorded Investment	46,920	38,005
Commercial and Industrial Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	37,786	36,874
Total LHFI With No Related Allowance Recorded	12,893	31,281
Total LHFI With an Allowance Recorded	17,824	518
Total LHFI Carrying Amount	30,717	31,799
Related Allowance	4,334	131
Average Recorded Investment	26,725	22,734
Consumer Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	2	17
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	2	17
Total LHFI Carrying Amount	2	17
Related Allowance	0	0
Average Recorded Investment	6	9
State and Other Political Subdivision Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	8,688	0
Total LHFI With No Related Allowance Recorded	4,079	0
Total LHFI With an Allowance Recorded	4,516	0
Total LHFI Carrying Amount	8,595	0
Related Allowance	516	0
Average Recorded Investment	4,297	0
Other Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	1,418	556
Total LHFI With No Related Allowance Recorded	230	0
Total LHFI With an Allowance Recorded	1,052	556
Total LHFI Carrying Amount	1,282	556
Related Allowance	1,052	41
Average Recorded Investment	804	325
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	1,794	1,704
Total LHFI With No Related Allowance Recorded	1,528	1,206
Total LHFI With an Allowance Recorded	24	199
Total LHFI Carrying Amount	1,552	1,405
Related Allowance	0	75
Average Recorded Investment	1,738	1,923
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	4,951	6,031
Total LHFI With No Related Allowance Recorded	95	160
Total LHFI With an Allowance Recorded	3,868	4,576
Total LHFI Carrying Amount	3,963	4,736
Related Allowance	39	1,331
Average Recorded Investment	4,328	4,693
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	8,282	15,205
Total LHFI With No Related Allowance Recorded	6,728	10,027
Total LHFI With an Allowance Recorded	2,748	396
Total LHFI Carrying Amount	9,476	10,423
Related Allowance	413	165
Average Recorded Investment	8,898	8,321
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	0	0
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	248	0
Total LHFI Carrying Amount	248	0
Related Allowance	0	0
Average Recorded Investment	$ 124	$ 0

LHFI and Allowance for Loan L_7

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, 2018USD ($)Contract	Dec. 31, 2017USD ($)Contract	Dec. 31, 2016USD ($)Contract
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	52	33	27
Pre-Modification Outstanding Recorded Investment	$ 30,878	$ 15,637	$ 12,162
Post-Modification Outstanding Recorded Investment	$ 29,328	$ 15,630	$ 12,106
Construction, Land Development and Other Land [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	1	1	1
Pre-Modification Outstanding Recorded Investment	$ 22	$ 341	$ 14
Post-Modification Outstanding Recorded Investment	$ 22	$ 325	$ 14
Secured by 1-4 Family Residential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	23	22	18
Pre-Modification Outstanding Recorded Investment	$ 2,102	$ 1,478	$ 1,386
Post-Modification Outstanding Recorded Investment	$ 1,660	$ 1,487	$ 1,391
Secured by Nonfarm, Nonresidential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	2	1	2
Pre-Modification Outstanding Recorded Investment	$ 1,780	$ 426	$ 717
Post-Modification Outstanding Recorded Investment	$ 1,780	$ 426	$ 717
Commercial and Industrial Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	23	8	5
Pre-Modification Outstanding Recorded Investment	$ 26,970	$ 12,836	$ 10,043
Post-Modification Outstanding Recorded Investment	$ 25,862	$ 12,836	$ 9,982
Consumer Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	3		1
Pre-Modification Outstanding Recorded Investment	$ 4		$ 2
Post-Modification Outstanding Recorded Investment	$ 4		$ 2
Other Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract		1
Pre-Modification Outstanding Recorded Investment		$ 556
Post-Modification Outstanding Recorded Investment		$ 556

LHFI and Allowance for Loan L_8

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, 2018USD ($)Contract	Dec. 31, 2017USD ($)Contract	Dec. 31, 2016USD ($)Contract
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	13	7	3
Recorded Investment | $	$ 15,935	$ 9,604	$ 2,154
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	5	4	1
Recorded Investment | $	$ 734	$ 78
Commercial and Industrial Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	6	3	2
Recorded Investment | $	$ 15,178	$ 9,526	$ 2,154
Consumer Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	1
Recorded Investment | $	$ 1

LHFI and Allowance for Loan L_9

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Modifications [Line Items]
Nonaccrual	$ 61,624	$ 67,575
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	2,218	2,105
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	14,718	19,022
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	9,621	12,608
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	927	212
Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	23,938	33,338
Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	205	135
Other Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	1,402	155
Troubled Debt Restructurings [Member]
Financing Receivable Modifications [Line Items]
Accruing	11,484	660	$ 53
Nonaccrual	16,706	23,211	14,427
Total	28,190	23,871	14,480
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	24	199	405
Total	24	199	405
Troubled Debt Restructurings [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	743	51	0
Nonaccrual	3,125	3,140	2,873
Total	3,868	3,191	2,873
Troubled Debt Restructurings [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	1,734	0	0
Nonaccrual	395	421	881
Total	2,129	421	881
Troubled Debt Restructurings [Member] | Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	9,007	53	53
Nonaccrual	12,620	19,434	10,266
Total	21,627	19,487	10,319
Troubled Debt Restructurings [Member] | Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0	0
Nonaccrual	2	17	2
Total	2	17	$ 2
Troubled Debt Restructurings [Member] | Other Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	556
Nonaccrual	540	0
Total	$ 540	$ 556

LHFI and Allowance for Loan _10

LHFI and Allowance for Loan Losses, LHFI - Additional Information (Details 2)	12 Months Ended
	Dec. 31, 2018USD ($)KeyRatioLoanPoolCreditRiskGrade	Dec. 31, 2017USD ($)
Financing Receivable, Recorded Investment, Aging [Abstract]
Number of days used as baseline in evaluating collateral documentation exceptions for loan policy	90 days
Number of key quality ratios | KeyRatio	6
LHFS past due 90 days or more	$ 37,400,000	$ 35,500,000
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

LHFI and Allowance for Loan _11

LHFI and Allowance for Loan Losses, LHFI - Summary of LHFI by Loan Type and Credit Quality Indicator (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Financing Receivable [Abstract]
Current		$ 8,756,553	$ 8,483,959
Financing Receivable, Recorded Investment, Past Due		17,691	18,433
Nonaccrual		61,624	67,575
Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due	[1]	856	2,171
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current		1,799,905	1,645,876
Financing Receivable, Recorded Investment, Past Due		10,869	10,413
Nonaccrual		14,718	19,022
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]	569	1,917
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current		2,209,406	2,178,640
Financing Receivable, Recorded Investment, Past Due		1,887	2,575
Nonaccrual		9,621	12,608
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current		542,597	517,744
Financing Receivable, Recorded Investment, Past Due		296
Nonaccrual		927	212
Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Current		1,513,131	1,535,003
Financing Receivable, Recorded Investment, Past Due		1,646	2,004
Nonaccrual		23,938	33,338
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due	[1]		12
Consumer Loans [Member]
Financing Receivable [Abstract]
Current		179,803	169,145
Financing Receivable, Recorded Investment, Past Due		2,440	2,638
Nonaccrual		205	135
Consumer Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due	[1]	287	242
State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Current		965,037	952,094
Financing Receivable, Recorded Investment, Past Due		186	389
Nonaccrual		8,595
Other Loans [Member]
Financing Receivable [Abstract]
Current		492,575	500,330
Financing Receivable, Recorded Investment, Past Due		83	22
Nonaccrual		1,402	155
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current		1,054,099	985,127
Financing Receivable, Recorded Investment, Past Due		284	392
Nonaccrual		2,218	2,105
Commercial LHFI [Member]
Financing Receivable [Abstract]
Financing receivable commercial		6,879,655	6,788,151
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		126,367	132,563
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		2,220,854	2,193,745
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		542,891	517,553
Commercial LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,538,715	1,570,345
Commercial LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		973,818	952,483
Commercial LHFI [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		488,782	494,581
Commercial LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		988,228	926,881
Commercial LHFI [Member] | Pass [Member]
Financing Receivable [Abstract]
Financing receivable commercial		6,712,604	6,554,846
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		123,191	127,405
Commercial LHFI [Member] | Pass [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		2,182,106	2,135,749
Commercial LHFI [Member] | Pass [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		537,958	517,036
Commercial LHFI [Member] | Pass [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,468,262	1,437,590
Commercial LHFI [Member] | Pass [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		958,214	936,420
Commercial LHFI [Member] | Pass [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		460,568	478,083
Commercial LHFI [Member] | Pass [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		982,305	922,563
Commercial LHFI [Member] | Special Mention [Member]
Financing Receivable [Abstract]
Financing receivable commercial		37,387	41,764
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		216	134
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	6,684
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		12,431	28,780
Commercial LHFI [Member] | Special Mention [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		5,250	5,850
Commercial LHFI [Member] | Special Mention [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		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	316
Commercial LHFI [Member] | Substandard [Member]
Financing Receivable [Abstract]
Financing receivable commercial		126,631	189,722
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		2,731	4,948
Commercial LHFI [Member] | Substandard [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		37,025	50,785
Commercial LHFI [Member] | Substandard [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		4,610	517
Commercial LHFI [Member] | Substandard [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		55,943	103,089
Commercial LHFI [Member] | Substandard [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		10,354	10,213
Commercial LHFI [Member] | Substandard [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		10,323	16,390
Commercial LHFI [Member] | Substandard [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		5,645	3,780
Commercial LHFI [Member] | Doubtful [Member]
Financing Receivable [Abstract]
Financing receivable commercial		3,033	1,819
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		229	76
Commercial LHFI [Member] | Doubtful [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		473	527
Commercial LHFI [Member] | Doubtful [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		2,079	886
Commercial LHFI [Member] | Doubtful [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		49	108
Commercial LHFI [Member] | Doubtful [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		203	222
Consumer LHFI [Member]
Financing Receivable [Abstract]
Financing receivable commercial		8,835,868	8,569,967
Current		1,929,437	1,752,484
Nonaccrual		13,770	16,669
Subtotal		1,956,213	1,781,816
Consumer LHFI [Member] | Past Due 30-89 Days [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		12,149	10,612
Consumer LHFI [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		857	2,051
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,825,492	1,675,311
Current		1,675,455	1,516,691
Nonaccrual		13,229	16,374
Subtotal		1,699,125	1,542,748
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		9,872	7,874
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		569	1,809
Consumer LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		2,220,914	2,193,823
Current		60	78
Subtotal		60	78
Consumer LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		543,820	517,956
Current		929	403
Subtotal		929	403
Consumer LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,538,715	1,570,345
Consumer LHFI [Member] | Consumer Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		182,448	171,918
Current		179,802	169,146
Nonaccrual		205	134
Subtotal		182,448	171,918
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 30-89 Days [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		2,153	2,396
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		288	242
Consumer LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		973,818	952,483
Consumer LHFI [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Financing receivable commercial		494,060	500,507
Current		5,278	5,926
Subtotal		5,278	5,926
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Financing receivable commercial		1,056,601	987,624
Current		67,913	60,240
Nonaccrual		336	161
Subtotal		68,373	60,743
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		$ 124	$ 342
[1]	Past due 90 days or more but still accruing interest.

LHFI and Allowance for Loan _12

LHFI and Allowance for Loan Losses, LHFI - Additional Information (Details 3)	12 Months Ended
	Dec. 31, 2018FactorLoanScale
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 unique qualitative factors used to analyze consumer loans | Factor	5
Number of loan types for consumer portfolio | Loan	5

LHFI and Allowance for Loan _13

LHFI and Allowance for Loan Losses, LHFI - Summary of Balance in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	$ 6,400	$ 1,700
Total	79,290	76,733
Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	6,354	1,743
Collectively	72,936	74,990
Total	79,290	76,733	$ 71,265	$ 67,619
Allowance for Loan Losses, LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	4,334	131
Collectively	23,025	22,720
Total	27,359	22,851	22,011
Allowance for Loan Losses, LHFI [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively	2,890	3,470
Total	2,890	3,470	3,241
Allowance for Loan Losses, LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	516
Collectively	474	789
Total	990	789	859
Allowance for Loan Losses, LHFI [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	1,052	41
Collectively	5,142	4,625
Total	6,194	4,666	2,492
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]
Individually		75
Collectively	7,390	7,790
Total	7,390	7,865	9,085
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	39	1,331
Collectively	8,602	9,543
Total	8,641	10,874	10,347
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	413	165
Collectively	21,963	23,263
Total	22,376	23,428	20,967
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	3,450	2,790
Total	$ 3,450	$ 2,790	$ 2,263

LHFI and Allowance for Loan _14

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, 2018	Dec. 31, 2017
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	$ 55,800	$ 48,900
Total LHFI	8,835,868	8,569,967
Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	55,835	48,936
LHFI, Collectively Evaluated For Impairment	8,780,033	8,521,031
Total LHFI	8,835,868	8,569,967
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	1,056,601	987,624
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	1,552	1,405
LHFI, Collectively Evaluated For Impairment	1,055,049	986,219
Total LHFI	1,056,601	987,624
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	1,825,492	1,675,311
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	3,963	4,736
LHFI, Collectively Evaluated For Impairment	1,821,529	1,670,575
Total LHFI	1,825,492	1,675,311
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	2,220,914	2,193,823
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	9,476	10,423
LHFI, Collectively Evaluated For Impairment	2,211,438	2,183,400
Total LHFI	2,220,914	2,193,823
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	543,820	517,956
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	248
LHFI, Collectively Evaluated For Impairment	543,572	517,956
Total LHFI	543,820	517,956
Commercial and Industrial Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	1,538,715	1,570,345
Commercial and Industrial Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	30,717	31,799
LHFI, Collectively Evaluated For Impairment	1,507,998	1,538,546
Total LHFI	1,538,715	1,570,345
Consumer Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	182,448	171,918
Consumer Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	2	17
LHFI, Collectively Evaluated For Impairment	182,446	171,901
Total LHFI	182,448	171,918
State and Other Political Subdivision Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	973,818	952,483
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	8,595
LHFI, Collectively Evaluated For Impairment	965,223	952,483
Total LHFI	973,818	952,483
Other Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Total LHFI	494,060	500,507
Other Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	1,282	556
LHFI, Collectively Evaluated For Impairment	492,778	499,951
Total LHFI	$ 494,060	$ 500,507

LHFI and Allowance for Loan _15

LHFI and Allowance for Loan Losses, LHFI - Change in Allowance for Loan Losses (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		$ 76,733
Provision for loan losses, LHFI		17,993	$ 15,094	$ 10,957
Balance at end of period		79,290	76,733
Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		76,733	71,265	67,619
Transfers	[1]	1,554
Loans charged-off		(29,489)	(21,147)	(18,930)
Recoveries		12,499	11,521	11,619
Net (charge-offs) recoveries		(16,990)	(9,626)	(7,311)
Provision for loan losses, LHFI		17,993	15,094	10,957
Balance at end of period		79,290	76,733	71,265
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		7,865	9,085
Transfers	[1]	584
Loans charged-off		(123)	(79)
Recoveries		1,124	1,428
Provision for loan losses, LHFI		(2,060)	(2,569)
Balance at end of period		7,390	7,865	9,085
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		10,874	10,347
Transfers	[1]	182
Loans charged-off		(1,629)	(950)
Recoveries		646	1,833
Provision for loan losses, LHFI		(1,432)	(356)
Balance at end of period		8,641	10,874	10,347
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		23,428	20,967
Transfers	[1]	446
Loans charged-off		(1,184)	(4,231)
Recoveries		133	396
Provision for loan losses, LHFI		(447)	6,296
Balance at end of period		22,376	23,428	20,967
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		2,790	2,263
Transfers	[1]	291
Loans charged-off			(5)
Recoveries		23	69
Provision for loan losses, LHFI		346	463
Balance at end of period		3,450	2,790	2,263
Allowance for Loan Losses, LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		22,851	22,011
Transfers	[1]	46
Loans charged-off		(18,823)	(8,286)
Recoveries		5,410	2,578
Provision for loan losses, LHFI		17,875	6,548
Balance at end of period		27,359	22,851	22,011
Allowance for Loan Losses, LHFI [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		3,470	3,241
Transfers	[1]	5
Loans charged-off		(2,089)	(2,546)
Recoveries		2,019	1,938
Provision for loan losses, LHFI		(515)	837
Balance at end of period		2,890	3,470	3,241
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		789	859
Provision for loan losses, LHFI		201	(70)
Balance at end of period		990	789	859
Allowance for Loan Losses, LHFI [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		4,666	2,492
Loans charged-off		(5,641)	(5,050)
Recoveries		3,144	3,279
Provision for loan losses, LHFI		4,025	3,945
Balance at end of period		$ 6,194	$ 4,666	$ 2,492
[1]	The allowance for loan losses balance related to the remaining loans acquired in the Heritage acquisition on April 15, 2011, the Bay Bank merger on March 16, 2012 and the Reliance merger on April 7, 2017, which were transferred from acquired impaired loans to LHFI during 2018.

Acquired Loans - Additional Inf

Acquired Loans - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018CreditRiskGrade	Apr. 07, 2017USD ($)
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities [Abstract]
Loans acquired in merger accounted for under FASB ASC Topic 310 30 | $		$ 7.9
Number of individual credit risk grades | CreditRiskGrade	10

Acquired Loans - Schedule of Ac

Acquired Loans - Schedule of Acquired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	$ 106,932	$ 261,517
Less allowance for loan losses, acquired loans	1,231	4,079	$ 11,397	$ 11,992
Net acquired loans	105,701	257,438
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	5,878	23,586
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	22,556	61,751
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	47,979	114,694
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	8,253	16,746
Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	15,267	31,506
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	1,356	2,600
Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	$ 5,643	$ 10,634

Acquired Loans - Changes in the

Acquired Loans - Changes in the Carrying Value of Acquired Loans (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016	Apr. 07, 2017
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		$ 257,438
Additions						$ 7,900
Accretion to interest income		9,514		$ 14,924	$ 18,405
Carrying value, net, ending		105,701		257,438
Acquired Not ASC 310-30 [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning	[1]	77,868		42,743
Transfers	[1],[3]	(59,916)	[2]	(36,719)
Additions	[1],[4]			109,548
Accretion to interest income	[1]	1,019		1,578
Payments received, net	[1]	(16,234)		(39,208)
Other	[1],[5]	74		(74)
Change in allowance for loan losses, acquired loans	[1]	0		0
Carrying value, net, ending	[1]	2,811		77,868	42,743
Acquired Impaired [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		179,570		218,107
Transfers	[3]	(26,497)	[2]	0
Additions	[4]			7,899
Accretion to interest income		9,514		14,924
Payments received, net		(62,519)		(68,317)
Other	[5]	(26)		(361)
Change in allowance for loan losses, acquired loans		2,848		7,318
Carrying value, net, ending		$ 102,890		$ 179,570	$ 218,107
[1]	“Acquired Not ASC 310-30” loans consist of loans that are not in scope for FASB ASC Topic 310-30.
[2]	During 2018, Trustmark transferred the remaining loans acquired in the Heritage acquisition on April 11, 2015, the Bay Bank merger on March 16, 2012 and the Reliance merger on April 7, 2017 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]	Loans acquired in the Reliance merger on April 7, 2017
[5]	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, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in accretable difference on acquired loans [Abstract]
Accretable yield at beginning of period		$ (31,426)	$ (38,918)	$ (52,672)
Additions due to acquisition	[1]		(784)
Accretion to interest income		9,514	14,924	18,405
Disposals, net		3,926	2,868	6,488
Transfers	[2]	5,874
Reclassification from nonaccretable difference	[3]	(5,610)	(9,516)	(11,139)
Accretable yield at end of period		$ (17,722)	$ (31,426)	$ (38,918)
[1]	Accretable yield on loans acquired from Reliance on April 7, 2017
[2]	During 2018, Trustmark transferred the remaining loans acquired in the Heritage acquisition on April 11, 2015, the Bay Bank merger on March 16, 2012 and the Reliance merger on April 7, 2017 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, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period		$ 4,079	$ 11,397	$ 11,992
Transfers	[1]	(1,554)
Provision for loan losses, acquired loans		(1,005)	(7,395)	3,757
Net (charge-offs) recoveries		(289)	77	(4,352)
Balance at end of period		$ 1,231	$ 4,079	$ 11,397
[1]	The allowance for loan losses balance related to the remaining loans acquired in the Heritage acquisition, the Bay Bank merger and the Reliance merger, which were transferred from acquired impaired loans to LHFI during 2018

Acquired Loans - Acquired Loans

Acquired Loans - Acquired Loans by Loan Type and Credit Quality Indicator (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		$ 105,701	$ 257,438
Acquired Loans, Aging [Abstract]
Current		104,377	255,506
Acquired Loans, Past Due		2,555	5,707
Nonaccrual	[1]	0	304
Total Acquired Loans		106,932	261,517
Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	1,546	2,434
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		5,786	22,601
Acquired Loans, Past Due		92	985
Nonaccrual	[1]	0	0
Total Acquired Loans		5,878	23,586
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]	87	861
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		21,303	58,490
Acquired Loans, Past Due		1,253	2,959
Nonaccrual	[1]	0	302
Total Acquired Loans		22,556	61,751
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]	481	654
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		46,795	113,256
Acquired Loans, Past Due		1,184	1,438
Nonaccrual	[1]	0	0
Total Acquired Loans		47,979	114,694
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]	978	898
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		8,237	16,614
Acquired Loans, Past Due		16	132
Nonaccrual	[1]	0	0
Total Acquired Loans		8,253	16,746
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]	0	0
Commercial and Industrial Loans [Member]
Acquired Loans, Aging [Abstract]
Current		15,267	31,504
Acquired Loans, Past Due		0	0
Nonaccrual	[1]	0	2
Total Acquired Loans		15,267	31,506
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		1,346	2,428
Acquired Loans, Past Due		10	172
Nonaccrual	[1]	0	0
Total Acquired Loans		1,356	2,600
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		5,643	10,613
Acquired Loans, Past Due		0	21
Nonaccrual	[1]	0	0
Total Acquired Loans		5,643	10,634
Other Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	0	21
Commercial LHFI [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		87,740	212,826
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		5,227	22,338
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		5,371	17,348
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		47,979	114,660
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		8,253	16,340
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		15,267	31,506
Commercial LHFI [Member] | Other Loans [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		5,643	10,634
Commercial LHFI [Member] | Pass [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		62,437	167,079
Commercial LHFI [Member] | Pass [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		4,923	17,150
Commercial LHFI [Member] | Pass [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		4,341	14,021
Commercial LHFI [Member] | Pass [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		34,933	95,147
Commercial LHFI [Member] | Pass [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		7,653	12,730
Commercial LHFI [Member] | Pass [Member] | Commercial and Industrial Loans [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		6,560	22,157
Commercial LHFI [Member] | Pass [Member] | Other Loans [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		4,027	5,874
Commercial LHFI [Member] | Special Mention [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		71	2,067
Commercial LHFI [Member] | Special Mention [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		26	234
Commercial LHFI [Member] | Special Mention [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		45	298
Commercial LHFI [Member] | Special Mention [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans			1,400
Commercial LHFI [Member] | Special Mention [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans			102
Commercial LHFI [Member] | Special Mention [Member] | Commercial and Industrial Loans [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans			15
Commercial LHFI [Member] | Special Mention [Member] | Other Loans [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans			18
Commercial LHFI [Member] | Substandard [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		22,174	40,660
Commercial LHFI [Member] | Substandard [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		278	4,690
Commercial LHFI [Member] | Substandard [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		534	3,029
Commercial LHFI [Member] | Substandard [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		12,614	17,583
Commercial LHFI [Member] | Substandard [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		190	3,031
Commercial LHFI [Member] | Substandard [Member] | Commercial and Industrial Loans [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		6,942	7,585
Commercial LHFI [Member] | Substandard [Member] | Other Loans [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		1,616	4,742
Commercial LHFI [Member] | Doubtful [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		3,058	3,020
Commercial LHFI [Member] | Doubtful [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans			264
Commercial LHFI [Member] | Doubtful [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		451
Commercial LHFI [Member] | Doubtful [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		432	530
Commercial LHFI [Member] | Doubtful [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		410	477
Commercial LHFI [Member] | Doubtful [Member] | Commercial and Industrial Loans [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans		1,765	1,749
Consumer LHFI [Member]
Acquired Loans, Aging [Abstract]
Current		18,121	46,064
Nonaccrual	[1]		124
Subtotal		19,192	48,691
Total Acquired Loans		106,932	261,517
Consumer LHFI [Member] | Past Due 30-89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		586	1,905
Consumer LHFI [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		485	598
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		642	1,188
Subtotal		651	1,248
Total Acquired Loans		5,878	23,586
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		5	46
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	14
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current		16,133	42,008
Nonaccrual	[1]		124
Subtotal		17,185	44,403
Total Acquired Loans		22,556	61,751
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		571	1,687
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		481	584
Consumer LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current			34
Subtotal			34
Total Acquired Loans		47,979	114,694
Consumer LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current			406
Subtotal			406
Total Acquired Loans		8,253	16,746
Consumer LHFI [Member] | Commercial and Industrial Loans [Member]
Acquired Loans, Aging [Abstract]
Total Acquired Loans		15,267	31,506
Consumer LHFI [Member] | Consumer Loans [Member]
Acquired Loans, Aging [Abstract]
Current		1,346	2,428
Subtotal		1,356	2,600
Total Acquired Loans		1,356	2,600
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 30-89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		10	172
Consumer LHFI [Member] | Other Loans [Member]
Acquired Loans, Aging [Abstract]
Total Acquired Loans		$ 5,643	$ 10,634
[1]	Acquired loans not accounted for under FASB ASC Topic 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, 2018	Dec. 31, 2017
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		$ 2,555	$ 5,707
Nonaccrual	[1]	0	304
Current		104,377	255,506
Acquired Loans		106,932	261,517
Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		878	2,340
Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		131	933
Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	[2]	1,546	2,434
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		92	985
Nonaccrual	[1]	0	0
Current		5,786	22,601
Acquired Loans		5,878	23,586
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		5	34
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	90
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]	87	861
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		1,253	2,959
Nonaccrual	[1]	0	302
Current		21,303	58,490
Acquired Loans		22,556	61,751
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		664	1,691
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		108	614
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]	481	654
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		1,184	1,438
Nonaccrual	[1]	0	0
Current		46,795	113,256
Acquired Loans		47,979	114,694
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		206	467
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	73
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]	978	898
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		16	132
Nonaccrual	[1]	0	0
Current		8,237	16,614
Acquired Loans		8,253	16,746
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		2	132
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		14	0
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]	0	0
Commercial and Industrial Loans [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		0	0
Nonaccrual	[1]	0	2
Current		15,267	31,504
Acquired Loans		15,267	31,506
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		10	172
Nonaccrual	[1]	0	0
Current		1,346	2,428
Acquired Loans		1,356	2,600
Consumer Loans [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		1	16
Consumer Loans [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due		9	156
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	21
Nonaccrual	[1]	0	0
Current		5,643	10,613
Acquired Loans		5,643	10,634
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	$ 21
[1]	Acquired loans not accounted for under FASB ASC Topic 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 (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	$ 425,343	$ 415,778
Less accumulated depreciation and amortization	247,160	237,425
Premises and equipment, net	178,183	178,353
Assets held for sale	485	986
Total premises and equipment, net	178,668	179,339
Land [Member]
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	52,779	52,335
Building and Leasehold Improvements [Member]
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	202,912	197,372
Furniture and Equipment [Member]
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	$ 169,652	$ 166,071

Premises and Equipment, Net - A

Premises and Equipment, Net - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)Branch	Dec. 31, 2017USD ($)Branch	Dec. 31, 2016USD ($)
Property Plant And Equipment [Abstract]
Number of branches held for sale | Branch	3	3
Property valuation adjustments	$ 173	$ 338	$ 750
Premises and Equipment, Net, by Type [Abstract]
Depreciation and amortization of premises and equipment	$ 14,300	$ 14,300	$ 13,200

Mortgage Banking - Schedule of

Mortgage Banking - Schedule of Activity in the Mortgage Servicing Rights (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Mortgage servicing rights [Abstract]
Balance at beginning of period	$ 84,269	$ 80,239
Origination of servicing assets	15,759	15,860
Change in fair value [Abstract]
Due to market changes	7,342	(1,050)
Due to runoff	(11,774)	(10,780)
Balance at end of period	$ 95,596	$ 84,269

Mortgage Banking - Additional I

Mortgage Banking - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)CPR	Dec. 31, 2017USD ($)CPR	Dec. 31, 2016USD ($)
Schedule of changes in the reserve for mortgage loan [Abstract]
Assumed average prepayment speed | CPR	8.19	9.14
Average discount rate (in hundredths)	10.04%	10.28%
Annual servicing fee	$ 21.9	$ 21.4	$ 20.4
Servicing fee income percentage of outstanding balance of underlying loans (in hundredths)	0.33%
Mortgage servicing rights [Abstract]
Residential mortgage loans sold	$ 1,092	1,179	1,384
Gains on sales of residential mortgage loans, before tax	$ 21.6	$ 18.9	$ 20.5
Period of putback response		60 days

Mortgage Banking - Schedule o_2

Mortgage Banking - Schedule of Mortgage Loans Sold and Serviced for Others (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	$ 6,834,874	$ 6,624,005
Federal National Mortgage Association [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	4,204,336	4,128,614
Government National Mortgage Association [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	2,537,238	2,421,456
Federal Home Loan Mortgage Corporation [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	71,343	47,071
Other [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	$ 21,957	$ 26,864

Mortgage Banking - Changes in t

Mortgage Banking - Changes in the Reserve for Mortgage Loan Servicing Putback Expense (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of changes in the reserve for mortgage loan [Abstract]
Balance at beginning of period		$ 1,000	$ 1,130	$ 1,685
Provision for putback expenses		0	(836)	420
Other	[1]	0	706	(975)
Balance at end of period		$ 1,000	$ 1,000	$ 1,130
[1]	Includes fair value adjustments for loans transferred due to underwriting issues as well as adjustments based on Trustmark’s mortgage loan servicing putback reserve analysis.

Goodwill and Identifiable Int_3

Goodwill and Identifiable Intangible Assets - Goodwill by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 379,627	$ 366,156
Goodwill from Reliance merger during 2017		13,471
Adjustment during 2018	0
Balance, end of period	379,627	379,627
General Banking [Member]
Goodwill [Roll Forward]
Goodwill, beginning of period	334,603	321,132
Goodwill from Reliance merger during 2017		13,471
Adjustment during 2018	0
Balance, end of period	334,603	334,603
Insurance [Member]
Goodwill [Roll Forward]
Goodwill, beginning of period	45,024	45,024
Goodwill from Reliance merger during 2017		0
Adjustment during 2018	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, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 07, 2017
Goodwill [Line Items]
Impairment charge	$ 173,000	$ 338,000	$ 750,000
Goodwill	379,627,000	379,627,000	366,156,000
Amortization expense of identifiable intangible assets	5,200,000	6,200,000	6,900,000
Impairment losses on identifiable intangible assets	0	0	0
Future amortization expense for identifiable intangible assets [Abstract]
2,019	4,000,000
2,020	2,700,000
2,021	1,900,000
2,022	1,100,000
2,023	427,000
Reliance [Member]
Goodwill [Line Items]
Goodwill		13,500,000		$ 13,471,000
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, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 102,823	$ 103,513
Accumulated Amortization	91,711	87,153
Net Carrying Amount	$ 11,112	16,360
Remaining Weighted-Average Amortization Periods in Years	5 years 10 months 24 days
Core Deposit Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 87,674	87,674
Accumulated Amortization	78,353	73,494
Net Carrying Amount	$ 9,321	14,180
Remaining Weighted-Average Amortization Periods in Years	4 years 4 months 24 days
Insurance Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 13,824	13,824
Accumulated Amortization	12,348	12,026
Net Carrying Amount	$ 1,476	1,798
Remaining Weighted-Average Amortization Periods in Years	15 years 6 months
Banking Charters [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,325	1,325
Accumulated Amortization	1,010	943
Net Carrying Amount	$ 315	382
Remaining Weighted-Average Amortization Periods in Years	4 years 8 months 12 days
Borrower Relationship Intangible [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 0	690
Accumulated Amortization	0	690
Net Carrying Amount	$ 0	$ 0

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, 2018	Dec. 31, 2017		Dec. 31, 2016	[1]
Reconciliation Of Carrying Amount Of Real Estate Investments Roll Forward
Balance at beginning of period		$ 43,228	$ 62,051	[1]	$ 78,828
Additions	[2]	12,115	9,235		24,525
Disposals		(19,802)	(24,762)		(36,801)
Write-downs		(873)	(3,296)		(4,501)
Balance at end of period		34,668	43,228		62,051
Gain (losses), net on the sale of other real estate included in other real estate expense		$ 700	$ 2,087		$ 7,031
[1]	The changes and gains, net on other real estate for the year ended December 31, 2016 include covered other real estate.
[2]	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, 2018	Dec. 31, 2017	Dec. 31, 2016	[1]	Dec. 31, 2015	[1]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	$ 34,668	$ 43,228	$ 62,051		$ 78,828
Construction, Land Development And Other Land Properties [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	16,206	27,491
1 - 4 Family Residential Properties [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	4,983	5,081
Nonfarm, Nonresidential Properties [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	13,296	10,468
Other Real Estate Properties [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	$ 183	$ 188
[1]	The changes and gains, net on other real estate for the year ended December 31, 2016 include covered other real estate.

Other Real Estate - Other Rea_2

Other Real Estate - Other Real Estate, By Geographic Location (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	[1]	Dec. 31, 2015	[1]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate		$ 34,668	$ 43,228	$ 62,051		$ 78,828
Alabama [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate		6,873	11,714
Florida [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate		8,771	13,937
Mississippi [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	[2]	17,255	14,260
Tennessee [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate	[3]	1,025	2,535
Texas [Member]
Other real estate, excluding covered other real estate [Line Items]
Total other real estate		$ 744	$ 782
[1]	The changes and gains, net on other real estate for the year ended December 31, 2016 include covered other real estate.
[2]	Mississippi includes Central and Southern Mississippi Regions.
[3]	Tennessee includes Memphis, Tennessee and Northern Mississippi Regions.

Other Real Estate - Additional

Other Real Estate - Additional information (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Reconciliation Of Carrying Amount Of Real Estate Investments Roll Forward
Foreclosed residential real estate properties recorded as a result of obtaining physical possession of the property	$ 5	$ 5.1
Consumer mortgage loans and that formal foreclosure proceedings are in process	$ 1.1	$ 1.4

Deposits - Deposits Summary (De

Deposits - Deposits Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Noninterest-bearing demand	$ 2,937,594	$ 2,978,074
Interest-bearing demand	2,633,259	2,432,814
Savings	3,905,659	3,408,183
Time	1,887,899	1,758,441
Total deposits	$ 11,364,411	$ 10,577,512

Deposits - Interest Expense on

Deposits - Interest Expense on Deposits by Type (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest expense on deposits by type [Abstract]
Interest-bearing demand	$ 18,479	$ 6,820	$ 3,297
Savings	17,980	6,047	2,657
Time	17,477	9,850	6,794
Total	$ 53,936	$ 22,717	$ 12,748

Deposits - Additional Informati

Deposits - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Time deposits that exceed the FDIC insurance limit of $250 thousand	$ 406.6	$ 342.3

Deposits - Maturities of Intere

Deposits - Maturities of Interest-Bearing Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Maturities of interest-bearing deposits [Abstract]
2,019	$ 1,478,845
2,020	295,596
2,021	55,927
2,022	33,616
2023 and thereafter	23,915
Total time deposits	1,887,899	$ 1,758,441
Interest-bearing deposits with no stated maturity	6,538,918
Total interest-bearing deposits	$ 8,426,817	$ 7,599,438

Borrowings - Securities Sold Un

Borrowings - Securities Sold Under Repurchase Agreements - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Securities sold under repurchase agreements, secured by securities carrying amount	$ 163.3	$ 200.9

Borrowings - Securities Sold _2

Borrowings - Securities Sold Under Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Securities sold under repurchase agreements by collateral pledged
Total securities sold under repurchase agreements	$ 45,509	$ 118,694
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	6,721	68,246
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	$ 38,788	$ 50,448

Borrowings - Summary of Short-T

Borrowings - Summary of Short-Term Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Short Term Debt [Line Items]
Total short-term borrowings	$ 79,006	$ 971,049
Federal Home Loan Bank Advances [Member]
Short Term Debt [Line Items]
Total short-term borrowings		900,013
Serviced GNMA Loans Eligible for Repurchase [Member]
Short Term Debt [Line Items]
Total short-term borrowings	61,564	48,211
Other [Member]
Short Term Debt [Line Items]
Total short-term borrowings	$ 17,442	$ 22,825

Borrowings - Short-Term Borrowi

Borrowings - Short-Term Borrowings - Additional information (Details)	Oct. 19, 2018USD ($)	May 04, 2018USD ($)	Mar. 02, 2018USD ($)	Dec. 31, 2018USD ($)Loan	Dec. 31, 2017USD ($)Loan	Dec. 31, 2016USD ($)
Short-term Debt [Abstract]
Total short-term borrowings				$ 79,006,000	$ 971,049,000
Federal Home Loan Bank Advances [Member]
Short-term Debt [Abstract]
Total short-term borrowings					900,013,000
Dallas [Member]
Short-term Debt [Abstract]
Additional debt instrument borrowing capacity				$ 2,827,000,000	$ 1,771,000,000
Dallas [Member] | Federal Home Loan Bank Advances [Member]
Short-term Debt [Abstract]
Number of outstanding short-term FHLB advances | Loan				0	4
Total short-term borrowings					$ 900,000,000
Dallas [Member] | Federal Home Loan Bank Advances [Member] | Advance Four [Member]
Short-term Debt [Abstract]
Total short-term borrowings					$ 250,000,000
Maturity date					Oct. 19, 2018
Repayments of Debt	$ 125,000,000	$ 125,000,000
Dallas [Member] | Federal Home Loan Bank Advances [Member] | Advance One [Member]
Short-term Debt [Abstract]
Total short-term borrowings					$ 250,000,000
Interest rate (in hundredths)					1.44%
Weighted average remaining maturity					58 days
Weighted-average cost related to FHLB advances (in hundredths)					1.45%
Dallas [Member] | Federal Home Loan Bank Advances [Member] | Advance Three [Member]
Short-term Debt [Abstract]
Total short-term borrowings					$ 250,000,000
Maturity date					May 25, 2018
Repayments of Debt			$ 250,000,000
Debt instrument payoff date					March 2, 2018
Dallas [Member] | Federal Home Loan Bank Advances [Member] | Advance Two [Member]
Short-term Debt [Abstract]
Total short-term borrowings					$ 150,000,000
Interest rate (in hundredths)					1.48%
Weighted average remaining maturity					58 days
Weighted-average cost related to FHLB advances (in hundredths)					1.45%
Atlanta [Member]
Short-term Debt [Abstract]
Additional debt instrument borrowing capacity					$ 0
Atlanta [Member] | Federal Home Loan Bank Advances [Member]
Short-term Debt [Abstract]
Number of outstanding short-term FHLB advances | Loan				0	1
Total short-term borrowings					$ 13,000
Interest rate (in hundredths)					6.12%
Remaining maturity					72 days
Atlanta and Dallas [Member]
Short-term Debt [Abstract]
Interest expense, short-term borrowings				$ 4,400,000	$ 11,400,000	$ 1,800,000

Borrowings - Long-term Debt Ins

Borrowings - Long-term Debt Instruments - Additional information (Details) - Federal Home Loan Bank Advances [Member]	12 Months Ended
	Dec. 31, 2018USD ($)Loan	Dec. 31, 2017USD ($)Loan	Dec. 31, 2016USD ($)
Dallas [Member]
Long-Term Borrowings [Abstract]
Number of outstanding long-term FHLB advances | Loan	0	0
Atlanta [Member]
Long-Term Borrowings [Abstract]
Number of outstanding long-term FHLB advances | Loan	2	2
Weighted average remaining maturity	3 years 4 months 28 days	4 years 5 months 8 days
Weighted-average cost related to FHLB advances (in hundredths)	0.63%	0.63%
Atlanta [Member] | Minimum [Member]
Long-Term Borrowings [Abstract]
Interest rate (in hundredths)	0.08%	0.08%
Atlanta [Member] | Maximum [Member]
Long-Term Borrowings [Abstract]
Interest rate (in hundredths)	0.75%	0.75%
Atlanta and Dallas [Member]
Long-Term Borrowings [Abstract]
Interest expense, long-term	$ 6,000	$ 566,000	$ 2,100,000
Long Term Borrowing [Member] | BancTrust [Member] | Fair Market Value Adjustment [Member]
Long-Term Borrowings [Abstract]
Long-term FHLB advances	0	0
Long Term Borrowing [Member] | Atlanta [Member] | BancTrust [Member]
Long-Term Borrowings [Abstract]
Long-term FHLB advances	879,000	946,000
Long Term Borrowing [Member] | Atlanta [Member] | BancTrust [Member] | Minimum [Member]
Long-Term Borrowings [Abstract]
Long-term FHLB advances	153,000	171,000
Long Term Borrowing [Member] | Atlanta [Member] | BancTrust [Member] | Maximum [Member]
Long-Term Borrowings [Abstract]
Long-term FHLB advances	$ 726,000	$ 775,000

Borrowings - Junior Subordinate

Borrowings - Junior Subordinated Debt Securities - Additional information (Details) $ in Thousands	Aug. 18, 2006USD ($)Quarter	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Variable Interest Entity [Line Items]
Junior subordinated debt securities		$ 61,856	$ 61,856
Total assets		13,286,460	13,797,953	$ 13,352,333
Total liabilities and shareholders' equity		13,286,460	13,797,953
Common securities		13,717	14,115
Net income		$ 149,584	105,630	108,411
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		74	55	45
Dividends paid		$ 74	$ 55	$ 45

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, 2018	Dec. 31, 2017		Dec. 31, 2016
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Service charges on deposit accounts		$ 43,702	$ 44,003	[1]	$ 45,253	[1]
Bank card and other fees		28,905	28,286	[1]	27,906	[1]
Mortgage banking, net		34,674	29,902	[1]	28,212	[1]
Wealth management		30,338	30,340	[1]	30,492	[1]
Insurance commissions		40,481	38,168	[1]	36,764	[1]
Other, net		6,736	13,949	[1]	5,626	[1]
Security gains (losses), net		0	15	[1]	(310)	[1]
Total Noninterest Income		184,836	184,663	[1]	173,943	[1]
General Banking Segment [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Service charges on deposit accounts		43,699	44,001	[1]	45,252	[1]
Bank card and other fees		28,823	28,229	[1]	27,893	[1]
Mortgage banking, net		34,674	29,902	[1]	28,212	[1]
Wealth management		296	210	[1]	566	[1]
Other, net		6,630	13,823	[1]	5,446	[1]
Security gains (losses), net	[1]		15		(310)
Total Noninterest Income		114,122	116,180	[1]	107,059	[1]
Wealth Management Segment [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Service charges on deposit accounts		3	2	[1]	1	[1]
Bank card and other fees		82	57	[1]	13	[1]
Wealth management		30,042	30,130	[1]	29,926	[1]
Other, net		101	96	[1]	177	[1]
Total Noninterest Income		30,228	30,285	[1]	30,117	[1]
Insurance Segment [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Insurance commissions		40,481	38,168	[1]	36,764	[1]
Other, net		5	30	[1]	3	[1]
Total Noninterest Income		40,486	38,198	[1]	36,767	[1]
Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Service charges on deposit accounts		43,702	44,003	[1]	45,253	[1]
Bank card and other fees		27,008	28,036	[1]	27,243	[1]
Wealth management		30,338	30,340	[1]	30,492	[1]
Insurance commissions		40,481	38,168	[1]	36,764	[1]
Other, net		6,835	6,596	[1]	7,271	[1]
Total Noninterest Income		148,364	147,143	[1]	147,023	[1]
Topic 606 [Member] | General Banking Segment [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Service charges on deposit accounts		43,699	44,001	[1]	45,252	[1]
Bank card and other fees		26,926	27,979	[1]	27,230	[1]
Wealth management		296	210	[1]	566	[1]
Other, net		6,826	6,565	[1]	7,185	[1]
Total Noninterest Income		77,747	78,755	[1]	80,233	[1]
Topic 606 [Member] | Wealth Management Segment [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Service charges on deposit accounts		3	2	[1]	1	[1]
Bank card and other fees		82	57	[1]	13	[1]
Wealth management		30,042	30,130	[1]	29,926	[1]
Other, net		4	1	[1]	83	[1]
Total Noninterest Income		30,131	30,190	[1]	30,023	[1]
Topic 606 [Member] | Insurance Segment [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Insurance commissions		40,481	38,168	[1]	36,764	[1]
Other, net		5	30	[1]	3	[1]
Total Noninterest Income		40,486	38,198	[1]	36,767	[1]
Not Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Bank card and other fees	[2]	1,897	250	[1]	663	[1]
Mortgage banking, net	[2]	34,674	29,902	[1]	28,212	[1]
Other, net	[2]	(99)	7,353	[1]	(1,645)	[1]
Security gains (losses), net	[1],[2]		15		(310)
Total Noninterest Income	[2]	36,472	37,520	[1]	26,920	[1]
Not Topic 606 [Member] | General Banking Segment [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Bank card and other fees	[2]	1,897	250	[1]	663	[1]
Mortgage banking, net	[2]	34,674	29,902	[1]	28,212	[1]
Other, net	[2]	(196)	7,258	[1]	(1,739)	[1]
Security gains (losses), net	[1],[2]		15		(310)
Total Noninterest Income	[2]	36,375	37,425	[1]	26,826	[1]
Not Topic 606 [Member] | Wealth Management Segment [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Other, net	[2]	97	95	[1]	94	[1]
Total Noninterest Income	[2]	$ 97	$ 95	[1]	$ 94	[1]
[1]	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.
[2]	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, 2018	Dec. 31, 2017	Dec. 31, 2016
Current [Abstract]
Federal	$ 4,532	$ 16,959	$ 10,355
State	5,997	5,687	2,698
Deferred [Abstract]
Federal	9,392	7,280	15,647
State	2,348	1,820	2,353
Income tax provision excluding deferred tax asset revaluation and reversal of valuation allowance	22,269	31,746	31,053
Deferred tax expense (benefit) - re-measurement of deferred tax assets	0	25,619	0
Deferred tax expense (benefit) - reversal of valuation allowance	0	(8,650)	0
Income tax provision	$ 22,269	$ 48,715	$ 31,053

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of provision for tax from the federal rate to the effective tax rate [Abstract]
Income tax computed at statutory tax rate	$ 36,089	$ 54,021	$ 48,812
Tax exempt interest	(4,533)	(7,611)	(6,780)
Nondeductible interest expense	416	407	201
State income taxes, net	4,738	3,697	1,754
Income tax credits, net	(15,404)	(15,793)	(16,183)
Death benefit gains	(268)	(3,268)	0
Reversal of valuation allowance	0	(8,650)	0
Re-measurement of deferred tax assets	0	25,619	0
Other	1,231	293	3,249
Income tax provision	$ 22,269	$ 48,715	$ 31,053

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets [Abstract]
Loan purchase accounting	$ 1,564	$ 3,638
Other real estate	7,284	13,403
Allowance for loan losses	20,638	20,203
Deferred compensation	15,607	15,184
Realized built-in losses	12,182	12,932
Securities	3,929	4,869
Pension and other postretirement benefit plans	4,108	5,453
Interest on nonaccrual loans	806	774
Unrealized losses on securities available for sale	10,679	5,874
Stock-based compensation	2,192	2,067
Federal carryovers	1,606	4,569
Other	9,179	8,964
Gross deferred tax asset	89,774	97,930
Deferred tax liabilities [Abstract]
Goodwill and other identifiable intangibles	16,229	16,729
Premises and equipment	12,109	11,877
Mortgage servicing rights	14,415	9,964
Securities	1,519	1,345
Other	5,600	5,040
Gross deferred tax liability	49,872	44,955
Net deferred tax asset	$ 39,902	$ 52,975

Income Taxes - Changes in Unrec

Income Taxes - Changes in Unrecognized Tax Benefits (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Changes in unrecognized tax benefits [Roll Forward]
Balance at beginning of period	$ 1,105
Change due to tax positions taken during the current year	282
Change due to tax positions taken during a prior year	56
Change due to the lapse of applicable statute of limitations during the current year	(194)
Change due to settlements with taxing authorities during the current year	0
Balance at end of period	1,249
Accrued interest, net of federal benefit, at end of period	212
Unrecognized tax benefits that would impact the effective tax rate, if recognized, at end of period	$ 988

Defined Benefit and Other Pos_3

Defined Benefit and Other Postretirement Benefits - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Recognized net loss due to defined benefit plan termination				$ 17,644,000
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	$ 17,600,000
Trustmark's minimum required contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions			$ 148,000
Trustmark's contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions			275,000
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		$ 160,000
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			377,000	17,964,000
Recognized net loss due to defined benefit plan termination	$ 17,600,000		0	17,662,000	$ 0
Assets remained in this plan				0
Estimated future benefit payments [Abstract]
Accumulated other comprehensive loss expected to be recognized during next fiscal year as components of net periodic benefit cost			(371,000)
Supplemental Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, additional asset contributions on termination basis			3,426,000	3,451,000
Estimated future benefit payments [Abstract]
Accumulated other comprehensive loss expected to be recognized during next fiscal year as components of net periodic benefit cost			(625,000)
Accumulated other comprehensive loss expected to be recognized during next fiscal year as prior service cost			250,000
Defined Contribution Plan [Member]
Other Benefit Plans - Defined Contribution Plan [Abstract]
Trustmarks contribution to defined contribution plan			$ 7,900,000	$ 7,500,000	$ 7,200,000
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, 2018	Dec. 31, 2017	Dec. 31, 2016
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		$ 10,102	$ 75,900
Service cost		277	253	$ 428
Interest cost		332	1,461	3,355
Actuarial (gain) loss		(827)	391
Benefits paid		(705)	(68,583)
Settlement loss		0	680
Benefit obligation, end of year		9,179	10,102	75,900
Change in plan assets [ Roll Forward]
Fair value of plan assets, beginning of year		4,596	54,734
Actual return on plan assets		(314)	481
Employer contributions		377	17,964
Benefit payments for the Plan		(705)	(68,583)
Fair value of plan assets, end of year		3,954	4,596	54,734
Funded status at end of year - net liability		(5,225)	(5,506)
Amounts recognized in accumulated other comprehensive income (loss) [Abstract]
Net loss		2,170	3,187
Supplemental Retirement Plan [Member]
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year		57,930	58,495
Service cost		116	141	295
Interest cost		1,865	2,103	2,223
Actuarial (gain) loss		(3,228)	642
Benefits paid		(3,426)	(3,451)
Benefit obligation, end of year		53,257	57,930	58,495
Change in plan assets [ Roll Forward]
Fair value of plan assets, beginning of year		0	0
Employer contributions		3,426	3,451
Benefit payments for the Plan		(3,426)	(3,451)
Fair value of plan assets, end of year		0	0	$ 0
Funded status at end of year - net liability		(53,257)	(57,930)
Amounts recognized in accumulated other comprehensive income (loss) [Abstract]
Net loss		13,403	17,514
Prior service cost		859	1,109
Amounts recognized		$ 14,262	$ 18,623

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, 2018	Dec. 31, 2017	Dec. 31, 2016
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		$ 277	253	$ 428
Interest cost		332	1,461	3,355
Expected return on plan assets		(227)	(317)	(2,897)
Recognized net loss due to defined benefit plan termination	$ 17,600	0	17,662	0
Recognized net loss due to lump sum settlements		161	0	3,906
Recognized net actuarial loss		571	1,414	2,749
Net periodic benefit cost		1,114	20,473	7,541
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)		(1,017)	(18,168)	(3,572)
Total recognized in net periodic benefit cost and other comprehensive income (loss)		$ 97	$ 2,305	$ 3,969
Weighted-average assumptions as of end of year [Abstract]
Discount rate for benefit obligation (in hundredths)		3.97%	3.32%	3.71%
Discount rate for net periodic benefit cost (in hundredths)		3.32%	3.71%	3.86%
Expected long-term return on plan assets (in hundredths)		5.00%	5.00%	4.25%
Supplemental Retirement Plan [Member]
Net periodic benefit cost [Abstract]
Service cost		$ 116	$ 141	$ 295
Interest cost		1,865	2,103	2,223
Amortization of prior service credits		250	250	250
Recognized net actuarial loss		884	866	864
Net periodic benefit cost		3,115	3,360	3,632
Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes:
Net loss (gain)		(4,111)	(224)	(810)
Amortization of prior service cost		(250)	(250)	(250)
Net (gain) loss - Total recognized in other comprehensive income (loss)		(4,361)	(474)	(1,060)
Total recognized in net periodic benefit cost and other comprehensive income (loss)		$ (1,246)	$ 2,886	$ 2,572
Weighted-average assumptions as of end of year [Abstract]
Discount rate for benefit obligation (in hundredths)		3.97%	3.32%	3.71%
Discount rate for net periodic benefit cost (in hundredths)		3.32%	3.71%	3.86%

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, 2018	Dec. 31, 2017
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)	8.00%	6.00%
Exchange Traded Funds [Member] | Equity Securities [Member]
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	52.00%	48.00%
Exchange Traded Funds [Member] | Fixed Income [Member]
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	29.00%	32.00%
Exchange Traded Funds [Member] | International [Member]
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	11.00%	14.00%

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Asset target allocations [Abstract]
Fair value of plan assets	$ 3,954	$ 4,596	$ 54,734
Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	3,954	4,596
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	304	269
Money Market Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	304	269
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	2,044	2,199
Exchange Traded Equity Securities Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	2,044	2,199
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	444	666
International Exchange Traded Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	444	666
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	1,162	1,462
Exchange Traded Fixed Income Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	1,162	1,462
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, 2018USD ($)
Supplemental Retirement Plan [Member]
Estimated future benefit payments [Abstract]
2,019	$ 3,534
2,020	4,052
2,021	4,123
2,022	4,291
2,023	4,126
2024 - 2028	18,638
Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member] | Trustmark Capital Accumulation Plan [Member]
Estimated future benefit payments [Abstract]
2,019	218
2,020	283
2,021	382
2,022	438
2,023	517
2024 - 2028	$ 3,037

Stock and Incentive Compensat_3

Stock and Incentive Compensation Plans - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018shares
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)	1,018,337

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Performance Based Award [Member]
Shares [Roll Forward]
Nonvested shares, beginning of year (in shares)	213,516	237,136	212,309
Granted (in shares)	51,174	58,406	99,116
Released from restriction (in shares)	(55,351)	(67,279)	(40,888)
Forfeited (in shares)	(31,644)	(14,747)	(33,401)
Nonvested shares, end of year (in shares)	177,695	213,516	237,136
Weighted-Average Grant Date Fair Value [Abstract]
Nonvested shares, beginning of year (in dollars per share)	$ 25.37	$ 26.27	$ 24.14
Granted (in dollars per share)	31.88	33.31	20.18
Released from restriction (in dollars per share)	25.32	34.78	32.84
Forfeited (in dollars per share)	26.26	28.42	30.01
Nonvested shares, end of year (in dollars per share)	$ 27.10	$ 25.37	$ 26.27
Time-Vested Awards [Member]
Shares [Roll Forward]
Nonvested shares, beginning of year (in shares)	320,357	322,056	306,657
Granted (in shares)	118,325	105,524	139,791
Released from restriction (in shares)	(107,180)	(101,289)	(108,241)
Forfeited (in shares)	(9,632)	(5,934)	(16,151)
Nonvested shares, end of year (in shares)	321,870	320,357	322,056
Weighted-Average Grant Date Fair Value [Abstract]
Nonvested shares, beginning of year (in dollars per share)	$ 25.40	$ 22.65	$ 24.56
Granted (in dollars per share)	31.96	33.79	20.66
Released from restriction (in dollars per share)	23.02	25.35	23.74
Forfeited (in dollars per share)	29.30	26.52	22.24
Nonvested shares, end of year (in dollars per share)	$ 28.48	$ 25.40	$ 22.65

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Compensation expense [Abstract]
Recognized compensation expense	$ 3,870	$ 4,309	$ 3,684
Unrecognized compensation expense	5,172
Performance Based Award [Member]
Compensation expense [Abstract]
Recognized compensation expense	861	1,387	1,171
Unrecognized compensation expense	$ 1,624
Weighted average life of unrecognized compensation expense	1 year 7 months 22 days
Time-Vested Awards [Member]
Compensation expense [Abstract]
Recognized compensation expense	$ 3,009	$ 2,922	$ 2,513
Unrecognized compensation expense	$ 3,548
Weighted average life of unrecognized compensation expense	1 year 9 months 15 days

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)Lawsuit	Dec. 31, 2016USD ($)
Loss Contingencies [Line Items]
Unused commitments to extend credit	$ 3,918	$ 3,172
Lease Commitments [Abstract]
Rental expense	9.2	$ 9.3	$ 9.8
Pending or Threatened Litigation, Stanford Financial Group [Member]
Legal Proceedings [Abstract]
Lawsuits naming entity as defendant, number | Lawsuit		3
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Potential exposure to credit loss in the event of nonperformance	$ 100.2	$ 104.1
Letters of credit, maturity term - maximum	3 years
Collateral held, fair value	$ 29.8	$ 28.4

Commitments and Contingencies_2

Commitments and Contingencies - Future Minimum Rental Commitments Under Non-cancellable Operating Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2,019	$ 8,680
2,020	8,063
2,021	7,274
2,022	6,680
2,023	5,788
Thereafter	29,673
Total	$ 66,158

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 11, 2016
Stockholders Equity [Line items]
Capital conservation buffer rate	1.875%	1.25%
Reclassification adjustment from accumulated other comprehensive loss to retained earnings		$ 8,500,000
Dividends on common stock [Abstract]
Dividend potential for next fiscal year	$ 66,000,000
Period for which retained net income considered for approval	2 years
Common Stock [Member]
Dividends on common stock [Abstract]
Amount of stock authorized for repurchase				$ 100,000,000
Repurchase shares of common stock, value	$ 62,400,000		$ 750,000
Repurchase shares of common stock	2,000,000	0	34,000

Shareholders' Equity - Table of

Shareholders' Equity - Table of Actual Regulatory Capital Amounts and Ratios (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
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		$ 1,271,538	$ 1,243,240
Actual Regulatory Capital Ratio		11.77%	11.77%
Minimum Regulatory Capital Required Ratio		6.375%	5.75%
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		$ 1,331,538	$ 1,303,238
Actual Regulatory Capital Ratio		12.33%	12.33%
Minimum Regulatory Capital Required Ratio		7.875%	7.25%
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		$ 1,412,059	$ 1,384,050
Actual Regulatory Capital Ratio		13.07%	13.10%
Minimum Regulatory Capital Required Ratio		9.875%	9.25%
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		$ 1,331,538	$ 1,303,238
Actual Regulatory Capital Ratio		10.26%	9.67%
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		$ 1,311,548	$ 1,284,575
Actual Regulatory Capital Ratio		12.14%	12.16%
Minimum Regulatory Capital Required Ratio		6.375%	5.75%
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		$ 1,311,548	$ 1,284,575
Actual Regulatory Capital Ratio		12.14%	12.16%
Minimum Regulatory Capital Required Ratio		7.875%	7.25%
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		$ 1,392,069	$ 1,365,387
Actual Regulatory Capital Ratio		12.89%	12.93%
Minimum Regulatory Capital Required Ratio		9.875%	9.25%
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		$ 1,311,548	$ 1,284,575
Actual Regulatory Capital Ratio		10.13%	9.54%
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, 2018	Dec. 31, 2017	Dec. 31, 2016
Securities available for sale and transferred securities:
Net unrealized holding gains (losses) arising during the period, Before tax amount	$ (19,221)	$ (13,994)	$ (15,656)
Reclassification adjustment for net (gains) losses realized in net income, Before tax amount	0	(15)	310
Change in net unrealized holding loss on securities transferred to held to maturity, Before tax amount	3,761	4,721	9,830
Total securities available for sale and transferred securities, Before tax amount	(15,460)	(9,288)	(5,516)
Pension and other postretirement benefit plans:
Change in the actuarial loss of pension and other postretirement benefit plans, Before tax amount	3,742	(1,231)	(240)
Reclassification adjustments for changes realized in net income:
Net change in prior service costs, Before tax amount	250	250	250
Recognized net loss due to lump sum settlements, Before tax amount	161		3,906
Change in net actuarial loss, Before tax amount	1,225	1,962	716
Recognized net loss due to defined benefit plan termination, Before tax amount		17,662
Total pension and other postretirement benefit plans, Before tax amount	5,378	18,643	4,632
Cash flow hedge derivatives:
Change in accumulated gain (loss) on effective cash flow hedge derivatives, Before tax amount	497	198	(369)
Reclassification adjustment for (gain) loss realized in net income, Before tax amount	(322)	282	599
Total cash flow hedge derivatives, Before tax amount	175	480	230
Total other comprehensive income (loss), Before tax amount	(9,907)	9,835	(654)
Securities available for sale and transferred securities:
Net unrealized holding gains (losses) arising during the period, tax (expense) benefit	4,805	5,353	5,989
Reclassification adjustment for net (gains) losses realized in net income, tax (expense) benefit	0	6	(119)
Change in net unrealized holding loss on securities transferred to held to maturity, tax (expense) benefit	(940)	(1,806)	(3,760)
Total securities available for sale and transferred securities, tax (expense) benefit	3,865	3,553	2,110
Pension and other postretirement benefit plans:
Change in the actuarial loss of pension and other postretirement benefit plans, tax (expense) benefit	(936)	471	92
Reclassification adjustments for changes realized in net income:
Net change in prior service costs, tax (expense) benefit	(63)	(96)	(96)
Recognized net loss due to lump sum settlements, tax (expense) benefit	(39)		(1,494)
Change in net actuarial loss, tax (expense) benefit	(306)	(751)	(274)
Recognized net loss due to defined benefit plan termination, tax (expense) benefit		(6,755)
Total pension and other postretirement benefit plans, tax (expense) benefit	(1,344)	(7,131)	(1,772)
Cash flow hedge derivatives:
Change in accumulated gain (loss) on effective cash flow hedge derivatives, tax (expense) benefit	(124)	(76)	141
Reclassification adjustment for (gain) loss realized in net income, tax (expense) benefit	80	(108)	(229)
Total cash flow hedge derivatives, tax (expense) benefit	(44)	(184)	(88)
Total other comprehensive income (loss), tax (expense) benefit	2,477	(3,762)	250
Securities available for sale and transferred securities:
Net unrealized holding gains (losses) arising during the period, net of tax amount	(14,416)	(8,641)	(9,667)
Reclassification adjustment for net (gains) losses realized in net income, net of tax amount	0	(9)	191
Change in net unrealized holding loss on securities transferred to held to maturity, net of tax amount	2,821	2,915	6,070
Total securities available for sale and transferred securities, net of tax amount	(11,595)	(5,735)	(3,406)
Pension and other postretirement benefit plans:
Change in the actuarial loss of pension and other postretirement benefit plans, net of tax amount	2,806	(760)	(148)
Reclassification adjustments for changes realized in net income:
Net change in prior service costs, net of tax amount	187	154	154
Recognized net loss due to lump sum settlements, net of tax amount	122	0	2,412
Change in net actuarial loss, net of tax amount	919	1,211	442
Recognized net loss due to defined benefit plan termination, net of tax amount	0	10,907	0
Total pension and other postretirement benefit plans, net of tax amount	4,034	11,512	2,860
Cash flow hedge derivatives:
Change in accumulated gain (loss) on effective cash flow hedge derivatives, net of tax amount	373	122	(228)
Reclassification adjustment for (gain) loss realized in net income, net of tax amount	(242)	174	370
Total cash flow hedge derivatives, net of tax amount	131	296	142
Total other comprehensive income (loss), net of tax amount	$ (7,430)	$ 6,073	$ (404)

Shareholders' Equity - Changes

Shareholders' Equity - Changes in Balances of Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 1,571,701	$ 1,520,208	$ 1,473,057
Other comprehensive income (loss) before reclassification	(8,416)	(6,364)	(3,973)
Amounts reclassified from accumulated other comprehensive loss	986	12,437	3,569
Total other comprehensive income (loss), net of tax amount	(7,430)	6,073	(404)
Balance	1,591,453	1,571,701	1,520,208
Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act	(8,524)
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(26,535)	(20,800)	(17,394)
Other comprehensive income (loss) before reclassification	(11,595)	(5,726)	(3,597)
Amounts reclassified from accumulated other comprehensive loss	0	(9)	191
Total other comprehensive income (loss), net of tax amount	(11,595)	(5,735)	(3,406)
Balance	(43,824)	(26,535)	(20,800)
Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act	(5,694)
Defined Benefit Pension Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(13,468)	(24,980)	(27,840)
Other comprehensive income (loss) before reclassification	2,806	(760)	(148)
Amounts reclassified from accumulated other comprehensive loss	1,228	12,272	3,008
Total other comprehensive income (loss), net of tax amount	4,034	11,512	2,860
Balance	(12,324)	(13,468)	(24,980)
Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act	(2,890)
Cash Flow Hedge Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	278	(18)	(160)
Other comprehensive income (loss) before reclassification	373	122	(228)
Amounts reclassified from accumulated other comprehensive loss	(242)	174	370
Total other comprehensive income (loss), net of tax amount	131	296	142
Balance	469	278	(18)
Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act	60
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(39,725)	(45,798)	(45,394)
Other comprehensive income (loss) before reclassification	0	0	0
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Total other comprehensive income (loss), net of tax amount	0	0	0
Balance	(55,679)	$ (39,725)	$ (45,798)
Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act	$ 0

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Nonfinancial Assets and Liabilities [Abstract]
Outstanding balances in impaired loans	$ 55,800	$ 48,900
Impaired loans, related allowance	6,400	1,700
Foreclosed assets re-measured after initial recognition	19,200	26,600
Write-downs of allowance for foreclosed assets after initial recognition	873	3,300
Noninterest gain (loss) Mortgage banking, net for changes in fair value of LHFS	1,400	3,000	$ (2,500)
Interest earned on LHFS included in Interest and fees on LHFS and LHFI	4,900	4,900	$ 5,000
GNMA optional repurchase loans	$ 61,600	$ 48,200

Fair Value - Financial Assets a

Fair Value - Financial Assets and Liabilities Measured at Fair Value Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 1,811,813	$ 2,238,635
Loans held for sale	153,799	180,512
Mortgage servicing rights	95,596	84,269	$ 80,239
U.S. Government Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	30,335	45,285
Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	50,676	79,229
Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,811,813	2,238,635
Loans held for sale	153,799	180,512
Mortgage servicing rights	95,596	84,269
Other assets - derivatives	12,347	1,516
Other liabilities - derivatives	4,213	2,678
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	30,335	45,285
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	50,676	79,229
Recurring Basis [Member] | Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,730,802	2,114,121
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	5,006	(1,013)
Other liabilities - derivatives	66	616
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	1,811,813	2,238,635
Loans held for sale	153,799	180,512
Mortgage servicing rights	0	0
Other assets - derivatives	6,154	1,629
Other liabilities - derivatives	4,147	2,062
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	30,335	45,285
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	50,676	79,229
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	1,730,802	2,114,121
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	95,596	84,269
Other assets - derivatives	1,187	900
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, 2018	Dec. 31, 2017
MSR [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		$ 84,269	$ 80,239
Total net (loss) gain included in Mortgage banking, net	[1]	(4,432)	(11,830)
Additions		15,759	15,860
Sales		0	0
Ending Balance		95,596	84,269
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		7,342	(1,050)
Other Assets - Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		900	1,001
Total net (loss) gain included in Mortgage banking, net	[1]	4,390	4,165
Additions		0	0
Sales		(4,103)	(4,266)
Ending Balance		1,187	900
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		$ 636	$ (1,569)
[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 - Carrying Amounts a

Fair Value - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	$ 909,643	$ 1,056,486
Net LHFI	8,756,578	8,493,234
Acquired loans	105,701	257,438
Deposits	11,364,411	10,577,512
Long-term FHLB advances	879	946
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	350,391	336,383
Securities held to maturity	909,643	1,056,486
Deposits	11,364,411	10,577,512
Short-term liabilities	129,477	1,440,876
Long-term FHLB advances	879	946
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	350,391	336,383
Securities held to maturity	889,733	1,046,247
Deposits	11,365,203	10,577,858
Short-term liabilities	129,477	1,440,876
Long-term FHLB advances	821	946
Junior subordinated debt securities	53,196	45,773
Level 3 [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI	8,756,578	8,493,234
Acquired loans	105,701	257,438
Level 3 [Member] | Estimate Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI	8,757,817	8,507,469
Acquired loans	$ 105,701	$ 257,438

Fair Value - Fair Value and the

Fair Value - Fair Value and the Contractual Principal Outstanding of the LHFS (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair value and the contractual principal outstanding of the LHFS [Abstract]
Fair value of LHFS	$ 92,235	$ 132,300
LHFS contractual principal outstanding	89,056	129,347
Fair value less unpaid principal	$ 3,179	$ 2,953

Derivative Financial Instrume_3

Derivative Financial Instruments - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018USD ($)Contract	Dec. 31, 2017USD ($)Contract	Dec. 31, 2016USD ($)	Apr. 04, 2013USD ($)
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Accumulated net, after tax gain included in accumulated other comprehensive loss	$ 497,000	$ 198,000	$ (369,000)
Mortgage Servicing Rights Hedge [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total notional amount	318,000,000	349,000,000
Net (negative) positive ineffectiveness on MSR fair value	$ 2,400,000	254,000	(2,900,000)
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	$ 469,000	$ 278,000
The period over which OCI will be reclassified as interest expense	12 months
Estimated amount to be reclassified as a decrease to interest expense	$ 625,000
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	2
Aggregate notional amount of credit risk participation agreements	$ 23,100,000	$ 13,700,000
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	7	6
Aggregate notional amount of credit risk participation agreements	$ 39,000,000	$ 37,100,000
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Swap [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total notional amount	475,800,000	351,900,000
Termination value of derivatives	75,000	80,000
Collateral Posted	0
Derivatives not Designated as Hedging Instruments [Member] | Forward Contracts [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet obligations	132,000,000	182,100,000
Valuation adjustment	(1,800,000)	(237,000)
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	71,200,000	83,000,000
Valuation adjustment	$ 1,200,000	$ 900,000

Derivative Financial Instrume_4

Derivative Financial Instruments - Fair Value of Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	$ 6,112	$ 1,626
Fair value of derivative liability	2,369	1,819
Derivatives in Hedging Relationships [Member] | Interest Rate Swap [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	625	451
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	(1,088)
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	42	3
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	5	6
Derivatives not Designated as Hedging Instruments [Member] | Forward Contracts [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	1,773	237
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Swap [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	5,487	1,175
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Swap [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	2,369	1,819
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	561	75
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	1,187	900
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	$ 66	$ 616

Derivative Financial Instrume_5

Derivative Financial Instruments - Effects of Derivative Instruments on Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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	$ 322	$ (282)	$ (599)
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	(6,191)	(1,873)	13
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	$ (357)	$ (31)	$ 60

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Change in accumulated gain (loss) on effective cash flow hedge derivatives, net of tax amount	$ 373	$ 122	$ (228)
Derivatives in Hedging Relationships [Member]
Derivatives, Fair Value [Line Items]
Change in accumulated gain (loss) on effective cash flow hedge derivatives, net of tax amount	$ 373	$ 122	$ (228)

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, 2018	Dec. 31, 2017
Offsetting Derivative Assets
Gross Amounts of Recognized Assets, Offsetting of Derivative Assets	$ 6,112	$ 1,626
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	6,112	1,626
Financial Instruments, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Assets	(339)	(311)
Cash Collateral Received, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Assets	(620)	0
Net Amount, Offsetting of Derivative Assets	5,153	1,315
Offsetting Derivative Liabilities
Gross Amounts of Recognized Liabilities, Offsetting of Derivative Liabilities	2,369	1,819
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	2,369	1,819
Financial Instruments, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Liabilities	(339)	(311)
Cash Collateral Posted, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Liabilities	0	(100)
Net Amount, Offsetting of Derivative Liabilities	$ 2,030	$ 1,408

Segment Information - Additiona

Segment Information - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018Segment
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, 2018	Dec. 31, 2017		Dec. 31, 2016
Segment Reporting Information [Line Items]
Net interest income	$ 419,420	$ 407,550		$ 387,533
Provision for loan losses, net	16,988	7,699		14,714
Noninterest income	184,836	184,663	[1]	173,943	[1]
Noninterest expense	415,415	430,169		407,298
Income Before Income Taxes	171,853	154,345		139,464
Income taxes	22,269	48,715		31,053
Net Income	149,584	105,630		108,411
Selected Financial Information
Total assets	13,286,460	13,797,953		13,352,333
Depreciation and amortization	38,940	38,471		36,613
General Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	418,968	406,406		386,596
Provision for loan losses, net	16,988	7,699		14,714
Noninterest income	114,122	116,180	[1]	107,059	[1]
Noninterest expense	357,703	373,221		354,555
Income Before Income Taxes	158,399	141,666		124,386
Income taxes	18,885	43,960		25,303
Net Income	139,514	97,706		99,083
Selected Financial Information
Total assets	13,207,850	13,724,193		13,278,668
Depreciation and amortization	38,188	37,710		35,692
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest income	226	910		726
Noninterest income	30,228	30,285	[1]	30,117	[1]
Noninterest expense	26,856	27,561		24,165
Income Before Income Taxes	3,598	3,634		6,678
Income taxes	900	1,390		2,554
Net Income	2,698	2,244		4,124
Selected Financial Information
Total assets	9,691	5,592		7,501
Depreciation and amortization	180	131		174
Insurance [Member]
Segment Reporting Information [Line Items]
Net interest income	226	234		211
Noninterest income	40,486	38,198	[1]	36,767	[1]
Noninterest expense	30,856	29,387		28,578
Income Before Income Taxes	9,856	9,045		8,400
Income taxes	2,484	3,365		3,196
Net Income	7,372	5,680		5,204
Selected Financial Information
Total assets	68,919	68,168		66,164
Depreciation and amortization	$ 572	$ 630		$ 747
[1]	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, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Other assets	$ 498,864	$ 532,442
Total Assets	13,286,460	13,797,953	$ 13,352,333
Liabilities and Shareholders' Equity:
Junior subordinated debt securities	61,856	61,856
Shareholders' equity	1,591,453	1,571,701	1,520,208	$ 1,473,057
Total Liabilities and Shareholders' Equity	13,286,460	13,797,953
Expense:
Net Income	149,584	105,630	108,411
Operating Activities
Net income	149,584	105,630	108,411
Adjustments to reconcile net income to net cash provided by operating activities:
Other	(3,016)	6,430	2,932
Net cash from operating activities	239,198	206,607	148,337
Investing Activities
Net cash from investing activities	438,787	(348,862)	(649,664)
Financing Activities
Cash dividends paid on common stock	(62,425)	(62,795)	(62,666)
Net cash from financing activities	(664,192)	150,317	551,282
Net change in cash and cash equivalents	13,793	8,062	49,955
Cash and cash equivalents at beginning of year	335,768	327,706	277,751
Cash and cash equivalents at end of year	349,561	335,768	327,706
Trustmark Corp (Parent Company Only) [Member]
Assets
Investment in banks	1,637,338	1,617,238
Other assets	16,975	17,349
Total Assets	1,654,313	1,634,587
Liabilities and Shareholders' Equity:
Accrued expense	1,004	1,030
Junior subordinated debt securities	61,856	61,856
Shareholders' equity	1,591,453	1,571,701
Total Liabilities and Shareholders' Equity	1,654,313	1,634,587
Revenue:
Dividends received from banks	128,592	65,663	65,987
Earnings of subsidiaries over distributions	23,791	42,211	44,756
Other income	86	71	60
Total Revenue	152,469	107,945	110,803
Expense:
Other expense	2,885	2,315	2,392
Total Expense	2,885	2,315	2,392
Net Income	149,584	105,630	108,411
Operating Activities
Net income	149,584	105,630	108,411
Adjustments to reconcile net income to net cash provided by operating activities:
Net change in investment in subsidiaries	(23,791)	(42,211)	(44,756)
Other	(1,395)	(1,697)	(739)
Net cash from operating activities	124,398	61,722	62,916
Investing Activities
Payment for investments in subsidiaries	0	(30,755)	0
Repayment for investments in subsidiaries		32,000
Net cash from investing activities	0	1,245	0
Financing Activities
Cash dividends paid on common stock	(62,425)	(62,795)	(62,666)
Other common stock transactions, net	(62,421)		(857)
Net cash from financing activities	(124,846)	(62,795)	(63,523)
Net change in cash and cash equivalents	(448)	172	(607)
Cash and cash equivalents at beginning of year	16,885	16,713	17,320
Cash and cash equivalents at end of year	$ 16,437	$ 16,885	$ 16,713

Parent Company Only Financial_4

Parent Company Only Financial Information - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements Captions [Line Items]
Income taxes paid	$ 12,435	$ 7,371	$ 24,836
Trustmark Corp (Parent Company Only) [Member]
Condensed Financial Statements Captions [Line Items]
Income taxes paid	12,400	7,400	24,800
Interest paid		$ 283	$ 600
Interest received	$ 320