Trustmark (TRMK) 10-K 18 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Jan. 31, 2021	Jun. 30, 2020
Cover [Abstract]
Entity Registrant Name	TRUSTMARK CORP
Entity Central Index Key	0000036146
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 920.2
Entity Common Stock, Shares Outstanding		63,408,802
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Trading Symbol	TRMK
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock, no par value
Security Exchange Name	NASDAQ
Entity File Number	000-3683
Entity Incorporation, State or Country Code	MS
Entity Tax Identification Number	64-0471500
Entity Address, Address Line One	248 East Capitol Street
Entity Address, City or Town	Jackson
Entity Address, State or Province	MS
Entity Address, Postal Zip Code	39201
City Area Code	601
Local Phone Number	208-5111
Document Annual Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
ICFR Auditor Attestation Flag	false
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the Proxy Statement for Trustmark’s 2021 Annual Meeting of Shareholders to be held April 27, 2021 are incorporated by reference into Part III of the Form 10-K report.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Assets
Cash and due from banks		$ 1,952,504	$ 358,916
Federal funds sold and securities purchased under reverse repurchase agreements		50
Securities available for sale, at fair value (amortized cost: $1,959,773-2020; $1,600,984-2019; allowance for credit losses: $0-2020)		1,991,815	1,602,404
Securities held to maturity, net of allowance for credit losses of $0 (fair value: $563,115-2020; $746,202-2019)		538,072	738,099
Paycheck Protection Program (PPP) loans		610,134
Loans held for sale (LHFS)		446,951	226,347
Loans held for investment (LHFI)	[1]	9,824,524	9,335,628
Less allowance for credit losses (ACL), LHFI	[1]	117,306	84,277
Net LHFI		9,707,218	9,251,351
Acquired loans	[1]		72,601
Less allowance for loan losses, acquired loans	[1]		815
Net acquired loans			71,786
Net LHFI and acquired loans		9,707,218	9,323,137
Premises and equipment, net		194,278	189,791
Mortgage servicing rights		66,464	79,394
Goodwill		385,270	379,627
Identifiable intangible assets, net		7,390	7,343
Other real estate		11,651	29,248
Operating lease right-of-use assets		30,901	31,182
Other assets		609,142	532,389
Total Assets		16,551,840	13,497,877
Deposits:
Noninterest-bearing		4,349,010	2,891,215
Interest-bearing		9,699,754	8,354,342
Total deposits		14,048,764	11,245,557
Federal funds purchased and securities sold under repurchase agreements		164,519	256,020
Other borrowings		168,252	85,396
Subordinated notes		122,921
Junior subordinated debt securities		61,856	61,856
ACL on off-balance sheet credit exposures	[1]	38,572	0
Operating lease liabilities		32,290	32,354
Other liabilities		173,549	155,992
Total Liabilities		14,810,723	11,837,175
Shareholders' Equity
Common stock, no par value: Authorized: 250,000,000 shares Issued and outstanding: 63,424,526 shares - 2020; 64,200,111 shares - 2019		13,215	13,376
Capital surplus		233,120	256,400
Retained earnings		1,495,833	1,414,526
Accumulated other comprehensive income (loss), net of tax		(1,051)	(23,600)
Total Shareholders' Equity		1,741,117	1,660,702
Total Liabilities and Shareholders' Equity		$ 16,551,840	$ 13,497,877
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Assets
Securities available-for-sale, amortized cost	$ 1,959,773,000	$ 1,600,984,000
Securities available-for-sale, allowance for credit Losses	0	0
Securities held to maturity, net of allowance for credit losses	0	0
Securities held to maturity, fair value	$ 563,115,000	$ 746,202,000
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)	63,424,526	64,200,111
Common stock, outstanding (in shares)	63,424,526	64,200,111

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Interest Income
Interest and fees on LHFS & LHFI		$ 390,803	$ 440,156		$ 395,969
Interest and fees on PPP loans		26,643
Interest and fees on acquired loans	[1]		8,373		17,115
Interest on securities:
Taxable		48,250	54,649		66,082
Tax exempt		1,079	1,711		2,236
Interest on federal funds sold and securities purchased under reverse repurchase agreements		1	240		14
Other interest income		1,559	5,363		4,196
Total Interest Income		468,335	510,492		485,612
Interest Expense
Interest on deposits		37,487	79,171		53,936
Interest on federal funds purchased and securities sold under repurchase agreements		755	1,420		4,788
Other interest expense		3,556	3,312		7,468
Total Interest Expense		41,798	83,903		66,192
Net Interest Income		426,537	426,589		419,420
Provision for credit losses (PCL)	[1]	36,113	10,797		17,993
Provision for loan losses, acquired loans	[1]		42		(1,005)
Net Interest Income After PCL		390,424	415,750		402,432
Noninterest Income
Service charges on deposit accounts		32,289	42,603	[2]	43,702	[2]
Bank card and other fees		31,022	31,736	[2]	28,905	[2]
Mortgage banking, net		125,822	29,822	[2]	34,674	[2]
Insurance commissions		45,176	42,396	[2]	40,481	[2]
Wealth management		31,625	30,679	[2]	30,338	[2]
Other, net		8,659	9,809	[2]	6,736	[2]
Total Noninterest Income		274,593	187,045	[2]	184,836	[2]
Noninterest Expense
Salaries and employee benefits		272,257	247,717		238,033
Services and fees		83,816	73,315		66,382
Net occupancy - premises		26,489	26,149		26,703
Equipment expense		23,277	23,733		24,830
Other real estate expense, net		1,956	3,906		2,002
Credit loss expense related to off-balance sheet credit exposures	[1]	8,934
Other expense		58,506	54,182		57,465
Total Noninterest Expense		475,235	429,002		415,415
Income Before Income Taxes		189,782	173,793		171,853
Income taxes		29,757	23,333		22,269
Net Income		$ 160,025	$ 150,460		$ 149,584
Earnings Per Share
Basic		$ 2.52	$ 2.33		$ 2.22
Diluted		$ 2.51	$ 2.32		$ 2.21
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.
[2]	During the first quarter of 2020, Trustmark revised the composition of its operating segments by moving the Retail Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes.  The prior period amounts presented include reclassifications to conform to the current period presentation.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income per consolidated statements of income	$ 160,025	$ 150,460	$ 149,584
Net unrealized gains (losses) on available for sale securities and transferred securities:
Net unrealized holding gains (losses) arising during the period	22,965	33,103	(14,416)
Change in net unrealized holding loss on securities transferred to held to maturity	2,383	2,704	2,821
Pension and other postretirement benefit plans:
Change in the actuarial loss of pension and other postretirement benefit plans	(3,846)	(4,278)	2,806
Reclassification adjustments for changes realized in net income:
Net change in prior service costs	112	187	187
Recognized net loss due to lump sum settlements	89	235	122
Change in net actuarial loss	846	597	919
Derivatives:
Change in the accumulated gain (loss) on effective cash flow hedge derivatives	0	(109)	373
Reclassification adjustment for (gain) loss realized in net income	0	(360)	(242)
Other comprehensive income (loss), net of tax	22,549	32,079	(7,430)
Comprehensive income	$ 182,574	$ 182,539	$ 142,154

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect Period Of Adoption Adjustment [Member]	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Retained Earnings [Member]Cumulative Effect Period Of Adoption Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2017	$ 1,571,701		$ 14,115	$ 369,124	$ 1,228,187		$ (39,725)
Balance (in shares) at Dec. 31, 2017			67,746,094
Net income per consolidated statements of income	149,584				149,584
Other comprehensive income (loss), net of tax	(7,430)						(7,430)
Cash dividends paid on common stock ($0.92 per share)	(62,425)				(62,425)
Shares withheld to pay taxes, long-term incentive plan	(1,426)		$ 25	(1,451)
Shares withheld to pay taxes, long-term incentive plan (in shares)			118,108
Accumulated other comprehensive loss adjustment, Tax Reform Act					8,524		(8,524)
Repurchase and retirement of common stock	(62,421)		$ (423)	(61,998)
Repurchase and retirement of common stock (in shares)			(2,029,807)
Compensation expense, long-term incentive plan	3,870			3,870
Balance at Dec. 31, 2018	1,591,453		$ 13,717	309,545	1,323,870		(55,679)
Balance (in shares) at Dec. 31, 2018			65,834,395
Net income per consolidated statements of income	150,460				150,460
Other comprehensive income (loss), net of tax	32,079						32,079
Cash dividends paid on common stock ($0.92 per share)	(59,804)				(59,804)
Shares withheld to pay taxes, long-term incentive plan	(1,658)		$ 28	(1,686)
Shares withheld to pay taxes, long-term incentive plan (in shares)			134,564
Repurchase and retirement of common stock	(56,615)		$ (369)	(56,246)
Repurchase and retirement of common stock (in shares)			(1,768,848)
Compensation expense, long-term incentive plan	4,787			4,787
Balance at Dec. 31, 2019	$ 1,660,702	$ (19,949)	$ 13,376	256,400	1,414,526	$ (19,949)	(23,600)
Balance (in shares) at Dec. 31, 2019	64,200,111		64,200,111
Net income per consolidated statements of income	$ 160,025				160,025
Other comprehensive income (loss), net of tax	22,549						22,549
Cash dividends paid on common stock ($0.92 per share)	(58,769)				(58,769)
Shares withheld to pay taxes, long-term incentive plan	(1,100)		$ 23	(1,123)
Shares withheld to pay taxes, long-term incentive plan (in shares)			111,373
Repurchase and retirement of common stock	(27,538)		$ (184)	(27,354)
Repurchase and retirement of common stock (in shares)			(886,958)
Compensation expense, long-term incentive plan	5,197			5,197
Balance at Dec. 31, 2020	$ 1,741,117		$ 13,215	$ 233,120	$ 1,495,833		$ (1,051)
Balance (in shares) at Dec. 31, 2020	63,424,526		63,424,526

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
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, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Activities
Net income per consolidated statements of income		$ 160,025	$ 150,460	$ 149,584
Adjustments to reconcile net income to net cash provided by operating activities:
Credit loss expense, net	[1]	45,047	10,839	16,988
Depreciation and amortization		41,325	39,420	38,940
Net amortization of securities		13,247	7,789	9,181
Gains on sales of loans, net		(94,986)	(27,301)	(21,615)
Compensation expense, long-term incentive plan		5,197	4,787	3,870
Deferred income tax provision		(19,800)	(3,880)	11,740
Proceeds from sales of loans held for sale		2,627,122	1,431,003	1,114,020
Purchases and originations of loans held for sale		(2,668,642)	(1,480,752)	(1,052,339)
Originations of mortgage servicing rights		(29,805)	(16,711)	(15,759)
Earnings on bank-owned life insurance		(5,099)	(5,592)	(5,358)
Net change in other assets		(49,653)	(30,729)	(1,891)
Net change in other liabilities		13,669	13,276	(1,277)
Other operating activities, net		27,699	23,838	(6,886)
Net cash from operating activities		65,346	116,447	239,198
Investing Activities
Proceeds from maturities, prepayments and calls of securities held to maturity		201,888	173,385	149,308
Proceeds from maturities, prepayments and calls of securities available for sale		680,294	425,260	423,617
Purchases of securities available for sale		(1,051,014)	(177,739)	(23,901)
Net proceeds from bank-owned life insurance		3,280	4,140	1,824
Net change in federal funds sold and securities purchased under reverse repurchase agreements		(50)	830	(215)
Net change in member bank stock		269	262	35,451
Net change in loans		(1,027,924)	(480,295)	(140,710)
Purchases of premises and equipment		(22,577)	(17,327)	(14,644)
Proceeds from sales of premises and equipment		2,803	3,248	772
Proceeds from sales of other real estate		17,343	11,182	20,502
Purchases of software		(8,252)	(13,412)	(13,195)
Investments in tax credit and other partnerships		(5,844)	(3,426)	(22)
Purchase of insurance book of business		(3,097)	(347)	0
Net cash used in business acquisition		(4,834)	0	0
Net cash from investing activities		(1,217,715)	(74,239)	438,787
Financing Activities
Net change in deposits		2,803,207	(118,854)	786,899
Net change in federal funds purchased and securities sold under repurchase agreements		(91,501)	205,549	(419,356)
Net change in short-term borrowings		517	561	(905,396)
Payments on long-term FHLB advances		(44)	(68)	(67)
Payments under finance lease obligations		(1,715)	(1,964)	0
Proceeds from subordinated notes		122,900	0	0
Common stock dividends		(58,769)	(59,804)	(62,425)
Repurchase and retirement of common stock		(27,538)	(56,615)	(62,421)
Shares withheld to pay taxes, long-term incentive plan		(1,100)	(1,658)	(1,426)
Net cash from financing activities		2,745,957	(32,853)	(664,192)
Net change in cash and cash equivalents		1,593,588	9,355	13,793
Cash and cash equivalents at beginning of year		358,916	349,561	335,768
Cash and cash equivalents at end of year		$ 1,952,504	$ 358,916	$ 349,561
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
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 183 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 2021 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. Financial Accounting Standards Board (FASB) Accounting Standard Update (ASU) 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” was adopted by Trustmark on January 1, 2020. ASU 2016-13 introduced FASB ASC Topic 326, which requires a current expected credit losses methodology for estimating allowances for credit losses and applies to all financial instruments carried at amortized cost, including securities held to maturity, and makes targeted improvements to the accounting for credit losses on securities available for sale. Under FASB ASC Topic 326, the allowance for credit losses is an estimate measured using relevant information about past events, including historical credit loss experience on financial assets with similar risk characteristics, current conditions, and reasonable and supportable forecasts that affect the collectability of the remaining cash flows over the contractual term of the financial assets. Trustmark has adopted a zero-credit loss assumption for certain classes of securities. This zero-credit loss assumption applies to debt issuances of the U.S. Treasury and agencies and instrumentalities of the United States government. The reasons behind the adoption of the zero-credit loss assumption were as follows: • High credit rating • Long history with no credit losses • Guaranteed by a sovereign entity • Widely recognized as “risk-free rate” • Can print its own currency • Currency is routinely held by central banks, used in international commerce, and commonly viewed as reserve currency • Currently under the U.S. Government conservatorship or receivership Trustmark continuously monitors any changes in economic conditions, credit downgrades, changes to explicit or implicit guarantees granted to certain debt issuers, and any other relevant information that would indicate potential credit deterioration and prompt Trustmark to reconsider its zero-credit loss assumption. Securities Available for Sale FASB ASC Subtopic 326-30, “Financial Instruments-Credit Losses-Available-for-Sale Debt Securities,” replaced the concept of other-than-temporarily impaired with the allowance for credit losses. Unlike securities held to maturity, securities available for sale are evaluated on an individual level and pooling of securities is not allowed. Quarterly, Trustmark evaluates if any security has a fair value less than its amortized cost. Once these securities are identified, in order to determine whether a decline in fair value resulted from a credit loss or other factors, Trustmark performs further analysis as outlined below: • Review the extent to which the fair value is less than the amortized cost and observe the security’s lowest credit rating as reported by third-party credit ratings companies. • The securities that violate the credit loss triggers above would be subjected to additional analysis that may include, but is not limited to: changes in market interest rates, changes in securities credit ratings, security type, service area economic factors, financial performance of the issuer/or obligor of the underlying issue and third-party guarantee. • If Trustmark determines that a credit loss exists, the credit portion of the allowance will be measured using a discounted cash flow (DCF) analysis using the effective interest rate as of the security’s purchase date. The amount of credit loss Trustmark records will be limited to the amount by which the amortized cost exceeds the fair value. The DCF analysis utilizes contractual maturities, as well as third-party credit ratings and cumulative default rates published annually by Moody’s Investor Service (Moody’s). Accrued interest receivable is excluded from the estimate of credit losses for securities available for sale. Securities Held to Maturity FASB ASC Subtopic 326-20, “Financial Instruments-Credit Losses-Measured at Amortized Cost,” requires institutions to measure expected credit losses on financial assets carried at amortized cost on a collective or pool basis when similar risks exist. Trustmark uses several levels of segmentation in order to measure expected credit losses for its held to maturity securities: • The portfolio is segmented into agency and non-agency securities. • The non-agency securities are separated into municipal, mortgage, and corporate securities. Each individual segment is categorized by third-party credit ratings. As discussed above, Trustmark has determined that for certain classes of securities it would be appropriate to assume the expected credit loss to be zero, which include debt issuances of the U.S. Treasury and agencies and instrumentalities of the United States government. This assumption is reviewed and attested to quarterly. Trustmark uses an internally built model to verify the accuracy of third-party provided calculations. Accrued interest receivable is excluded from the estimate of credit losses for securities held to maturity. 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 FASB ASC Topic 825, “Financial Instruments,” with interest income on the LHFS reported in interest and fees on LHFS and LHFI. Trustmark reports unrealized gains and losses resulting from changes in the fair value of the LHFS accounted for under the fair value option as noninterest income in mortgage banking, net. LHFS are actively managed and monitored and certain market risks of the loans may be mitigated through the use of derivatives. These derivative instruments are carried at fair value with changes in the fair value reported as noninterest income in mortgage banking, net. Changes in the fair value of the LHFS are largely offset by changes in the fair value of the derivative instruments. Election of the fair value option allows Trustmark to reduce the accounting volatility that would otherwise result from the asymmetry created by accounting for its LHFS at the lower of cost or fair value and the derivative instruments at fair value. Realized gains and losses upon ultimate sale of the loans are reported as noninterest income in mortgage banking, net. Government National Mortgage Association (GNMA) optional repurchase programs allow financial institutions to buy back individual delinquent mortgage loans that meet certain criteria from the securitized loan pool for which the institution provides servicing. At the servicer’s option and without GNMA’s prior authorization, the servicer may repurchase such a delinquent loan for an amount equal to 100 percent of the remaining principal balance of the loan. Under FASB ASC Topic 860, “Transfers and Servicing,” this buy-back option is considered a conditional option until the delinquency criteria are met, at which time the option becomes unconditional. When Trustmark is deemed to have regained effective control over these loans under the unconditional buy-back option, the loans can no longer be reported as sold and must be brought back onto the balance sheet as LHFS, regardless of whether Trustmark intends to exercise the buy-back option. These loans are reported as LHFS with the offsetting liability being reported as short-term borrowings. The fair value option election does not apply to the GNMA optional repurchase loans which do not meet the requirements under FASB ASC Topic 825 to be accounted for under the fair value option. Trustmark defers the upfront loan fees and costs related to the LHFS. In general, the LHFS are only retained on Trustmark’s balance sheet for 30 to 45 days before they are pooled and sold in the secondary market. The difference between deferring these loan fees and costs until the loans are sold and recognizing them in earnings as incurred as required by FASB ASC Subtopic 825-10 is considered immaterial. Deferred loan fees and costs are reflected in the basis of the LHFS and, as such, impact the resulting gain or loss when the loans are sold. Loans Held for Investment (LHFI) LHFI are loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off and are reported at amortized cost net of the allowance for credit losses. Amortized cost is 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. 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. 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, “Receivables-Troubled Debt Restructurings by Creditors.” 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. Purchased Credit Deteriorated (PCD) Loans Trustmark has purchased loans, some of which have experienced more than insignificant credit deterioration since origination. An initial allowance for credit losses for PCD loans is determined at acquisition using the same allowance for credit losses methodology as the LHFI. The initial allowance for credit losses determined on a collective basis is allocated to individual loans. PCD loans are reported at the amortized cost, which equals the loan purchased price plus the initial allowance for credit losses. The difference between the amortized cost basis of the PCD loan and the par value of the loan is the noncredit premium or discount, which is amortized into interest income over the life of the loan. Subsequent changes to the allowance for credit losses are recorded through the PCL. Upon adoption of FASB ASC Topic 326, Trustmark elected to maintain pools of loans that were previously accounted for under FASB ASC Subtopic 310-30, “Receivables-Loans and Debt Securities Acquired with Deteriorated Credit Quality,” and will continue to account for these pools as a unit of account. Loans are only removed from the existing loan pools if they are written off, paid off or sold. Upon adoption of FASB ASC Topic 326, the allowance for credit losses was determined for each pool and added to the pool’s carrying value to establish a new amortized cost basis. The difference between the unpaid principal balance of the pool and the new amortized cost basis is the noncredit premium or discount which will be amortized into interest income over the remaining life of the pool. Changes to the allowance for credit losses after adoption of FASB ASC Topic 326 are recorded through the PCL. Allowance for Credit Losses, LHFI (ACL) Trustmark’s ACL methodology for LHFI is based upon guidance within FASB ASC Subtopic 326-20 as well as regulatory guidance from its primary regulator. The ACL is a valuation account that is deducted from the loans’ amortized cost basis to present the net amount expected to be collected on the loans. Credit quality within the LHFI portfolio is continuously monitored by Management and is reflected within the ACL for loans. The ACL is an estimate of expected losses inherent within Trustmark’s existing LHFI portfolio. The ACL for LHFI is adjusted through the PCL and reduced by the charge off of loan amounts, net of recoveries. The loan loss estimation process involves procedures to appropriately consider the unique characteristics of Trustmark’s LHFI portfolio segments. These segments are further disaggregated into loan classes, the level at which credit risk is estimat ed. When computing allowance levels, credit loss assumptions are estimated using a model that categorizes loan pools based on loss history, delinquency status and other credit trends and risk characteristics, including current conditions and reasonable and supportable forecasts about the future. 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. Determining the appropriateness of the allowance is complex and requires judgement by Management about the effect of matters that are inherently uncertain. In future periods , evaluations of the overall LHFI portfolio, in light of the factors and forecasts then prevailing, may result in significant changes in the allowance and credit loss expense. Trustmark estimates the ACL using relevant available information, from internal and external sources, relating to past events, current conditions and reasonable and supportable forecasts including the COVID-19 pandemic effects. Trustmark uses a third-party software application to calculate the quantitative portion of the ACL using a methodology and assumptions specific to each loan pool. The qualitative portion of the 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: lending policies and procedures, economic conditions and concentrations of credit, nature and volume of the portfolio, performance trends, and external factors. The quantitative and qualitative portions of the allowance are added together to determine the total allowance for credit losses, which reflects Management’s expectations of future conditions based on reasonable and supportable forecasts. The methodology for estimating the amount of expected credit losses reported in the ACL has two basic components: a collective, or pooled, component for estimated expected credit losses for pools of loans that share similar risk characteristics, and an asset-specific component involving individual loans that do not share risk characteristics with other loans and the measurement of expected credit losses for such individual loans. In estimating the allowance for credit losses for the collective component, loans are segregated into loan pools based on loan product types and similar risk characteristics. Trustmark determined that reasonable and supportable forecasts could be made for a twelve-month period for all of its loan pools. To the extent the lives of the loans in the LHFI portfolio extend beyond this forecast period, Trustmark uses a reversion period of four quarters and reverts to the historical mean on a straight-line basis over the remaining life of the loans. The ACL for individual loans that do not share risk characteristics with other loans is measured as the difference between the discounted value of expected future cash flows, based in the effective interest rate at origination, and the amortized cost basis of the loan, or the net realizable value. The ACL is the difference between the loan’s net realizable value and its amortized cost basis (net of previous charge-offs and deferred loan fees and costs), except for collateral-dependent loans. A loan is collateral dependent when the borrower is experiencing financial difficulty and repayment of the loan is expected to be provided substantially through the sale of the collateral. The expected credit loss for collateral-dependent loans is measured as the difference between the amortized cost basis of the loan and the fair value of the collateral, adjusted for the estimated cost to sell. Fair value estimates for collateral-dependent loans are derived from appraised values based on the current market value or the ‘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. If the calculated expected credit loss is determined to be permanent or not recoverable, the amount of the expected credit loss is charged off. Accrued interest receivable is not included in the amortized cost basis of Trustmark’s LHFI and, therefore, excluded from the estimate of credit losses for LHFI. LHFI are charged off against the ACL, with any subsequent recoveries credited back to the ACL account. Expected recoveries may not exceed the aggregate of amounts previously charged off and expected to be charged off. Trustmark’s loan policy dictates the guidelines to be followed in determining when a loan is charged off. 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. ACL on Off-Balance Sheet Credit Exposures Under FASB ASC Subtopic 326-20, Trustmark is required to estimate expected credit losses for off-balance sheet credit exposures which are not unconditionally cancellable. Trustmark maintains a separate ACL on off-balance sheet credit exposures, including unfunded loan commitments and letters of credit. Expected credit losses for off-balance sheet credit exposures are estimated by calculating a commitment usage factor over the contractual period for exposures that are not unconditionally cancellable by Trustmark. Trustmark calculates a loan pool level unfunded amount for the period. Trustmark views the loan pools as either closed-ended or open-ended. Closed-ended loan pools are those that typically fund up to 100% such as other construction and nonowner-occupied. Open-ended loan pools are those that behave similar to a revolver such as the commercial and industrial and home equity line of credit loan pools. In addition to the unfunded balances, Trustmark uses a funding rate for loan pools that are considered open-ended. Trustmark calculates the funding rate of the open-ended loan pools each period. In order to mitigate volatility and incorporate historical experience in the funding rate, Trustmark uses a twelve-quarter moving average. For the closed-ended loan pools, Trustmark takes a conservative approach and uses a 100% funding rate. The expected funding rate is applied to each pool’s unfunded commitment balances to ensure that reserves will be applied to each pool based on balances expected to be funded based upon historical levels. In addition to the funding rate being applied to the unfunded commitment balance, a reserve rate is applied that incorporates both quantitative and qualitative aspects of the current period’s expected credit loss rate. The reserve rate is loan pool specific and is applied to the unfunded amount to ensure loss factors, both quantitative and qualitative, are being considered on the unfunded portion of the loan pool, consistent with the methodology applied to the funded loan pools. Adjustments to the ACL on off-balance sheet credit exposures are recorded to credit loss expense related to off-balance sheet credit exposures in noninterest expense. No credit loss estimate is reported for off-balance sheet credit exposures that are unconditionally cancellable by Trustmark or for undrawn amounts under such arrangements that may be drawn prior to the cancellation of the arrangement. 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 noninterest expense in other expense. Mortgage Servicing Rights (MSR) Trustmark recognizes as assets the rights to service mortgage loans based on the estimated fair value of the MSR when loans are sold and the associated servicing rights are retained. Trustmark has elected to account for the MSR at fair value. The fair value of the MSR is determined using discounted cash flow techniques benchmarked against third-party valuations. Estimates of fair value involve several assumptions, including the key valuation assumptions about market expectations of future prepayment rates, interest rates and discount rates which are provided by a third-party firm. Prepayment rates are projected using an industry standard prepayment model. The model considers other key factors, such as a wide range of standard industry assumptions tied to specific portfolio characteristics such as remittance cycles, escrow payment requirements, geographic factors, foreclosure loss exposure, VA no-bid exposure, delinquency rates and cost of servicing, including base cost and cost to service delinquent mortgages. Prevailing market conditions at the time of analysis are factored into the accumulation of assumptions and determination of servicing value. Trustmark economically hedges changes in the fair value of the MSR attributable to interest rates. See Note 1 – Significant Accounting Policies, “Derivative Financial Instruments – Derivatives Not Designated as Hedging Instruments” for information regarding these derivative instruments. Trustmark receives annual servicing fee income for loans serviced, which is recorded as noninterest income in mortgage banking, net. The fees are based on a contractual percentage of the outstanding principal or a 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 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

Cash and Due from Banks

Cash and Due from Banks	12 Months Ended
	Dec. 31, 2020
Cash And Cash Equivalents [Abstract]
Cash and Due from Banks	Note 2 – 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. Effective March 26, 2020, the Federal Reserve reduced reserve requirement ratios to zero percent, eliminating the reserve requirements for all depository institutions, in order to provide liquidity in the banking system to support lending to households and businesses due to the COVID-19 pandemic.

Securities Available for Sale a

Securities Available for Sale and Held to Maturity	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Securities Available for Sale and Held to Maturity	Note 3 – 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, 2020 and 2019 ($ 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, 2020 Cost Gains Losses Value Cost Gains Losses Value U.S. Government agency obligations $ 18,378 $ 144 $ (481 ) $ 18,041 $ — $ — $ — $ — Obligations of states and political subdivisions 5,198 637 — 5,835 26,584 258 (3 ) 26,839 Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 55,193 1,672 (3 ) 56,862 7,598 382 — 7,980 Issued by FNMA and FHLMC 1,421,861 20,768 (1,308 ) 1,441,321 67,944 2,397 — 70,341 Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 409,883 9,600 (46 ) 419,437 360,361 19,678 (55 ) 379,984 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 49,260 1,068 (9 ) 50,319 75,585 2,386 — 77,971 Total $ 1,959,773 $ 33,889 $ (1,847 ) $ 1,991,815 $ 538,072 $ 25,101 $ (58 ) $ 563,115 December 31, 2019 U.S. Government agency obligations $ 22,965 $ 69 $ (707 ) $ 22,327 $ 3,781 $ 220 $ — $ 4,001 Obligations of states and political subdivisions 24,952 513 — 25,465 31,781 434 (53 ) 32,162 Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 69,196 425 (369 ) 69,252 10,820 266 (10 ) 11,076 Issued by FNMA and FHLMC 714,350 2,171 (3,165 ) 713,356 96,631 286 (370 ) 96,547 Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 656,162 3,777 (1,713 ) 658,226 485,324 7,026 (656 ) 491,694 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 113,359 625 (206 ) 113,778 109,762 1,042 (82 ) 110,722 Total $ 1,600,984 $ 7,580 $ (6,160 ) $ 1,602,404 $ 738,099 $ 9,274 $ (1,171 ) $ 746,202 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, 2020 and 2019, the net unamortized, unrealized loss on the transferred securities included in accumulated other comprehensive loss in the accompanying balance sheet totaled approximately $8.9 million ($6.7 million, net of tax) and $12.1 million ($9.1 million, net of tax), respectively. ACL on Securities Securities Available for Sale Quarterly, Trustmark evaluates if any security has a fair value less than its amortized cost. Once these securities are identified, in order to determine whether a decline in fair value resulted from a credit loss or other factors, Trustmark performs further analysis. If Trustmark determines that a credit loss exists, the credit portion of the allowance is measured using a DCF analysis using the effective interest rate as of the security’s purchase date. The amount of credit loss Trustmark records will be limited to the amount by which the amortized cost exceeds the fair value. The DCF analysis utilizes contractual maturities, as well as third-party credit ratings and cumulative default rates published annually by Moody’s. At December 31, 2020, the results of the analysis did not identify any securities that violate the credit loss triggers; therefore, no DCF analysis was performed and no credit loss was recognized on any of the securities available for sale. Accrued interest receivable is excluded from the estimate of credit losses for securities available for sale. At December 31, 2020, accrued interest receivable totaled $4.0 million for securities available for sale and was reported in other assets on the accompanying consolidated balance sheet. Securities Held to Maturity At December 31, 2020, the potential credit loss exposure for Trustmark’s securities held to maturity was $26.6 million and consisted of municipal securities. After applying appropriate probability of default and loss given default assumptions, the total amount of current expected credit losses was deemed immaterial. Therefore, no reserve was recorded at December 31, 2020. Accrued interest receivable is excluded from the estimate of credit losses for securities held to maturity. At December 31, 2020, accrued interest receivable totaled $1.2 million for securities held to maturity and was reported in other assets on the accompanying consolidated balance sheet. At December 31, 2020, Trustmark had no securities held to maturity that were past due 30 days or more as to principal or interest payments. Trustmark had no securities held to maturity classified as nonaccrual at December 31, 2020. Trustmark monitors the credit quality of securities held to maturity on a monthly basis through credit ratings. The following table presents the amortized cost of Trustmark’s securities held to maturity by credit rating, as determined by Moody’s, at December 31, 2020 ($ in thousands): December 31, 2020 Aaa $ 511,488 Aa1 to Aa3 22,528 Not Rated (1) 4,056 Total $ 538,072 (1) Not rated securities primarily consist of Mississippi municipal general obligations. The table below includes securities with gross unrealized losses for which an allowance for credit losses has not been recorded and segregated by length of impairment at December 31, 2020 and 2019 ($ in thousands): Less than 12 Months 12 Months or More Total Gross Gross Gross Estimated Unrealized Estimated Unrealized Estimated Unrealized December 31, 2020 Fair Value Losses Fair Value Losses Fair Value Losses U.S. Government agency obligations $ — $ — $ 11,167 $ (481 ) $ 11,167 $ (481 ) Obligations of states and political subdivisions — — 667 (3 ) 667 (3 ) Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 1,636 (3 ) — — 1,636 (3 ) Issued by FNMA and FHLMC 324,905 (1,308 ) — — 324,905 (1,308 ) Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 29,398 (101 ) — — 29,398 (101 ) Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA — — 659 (9 ) 659 (9 ) Total $ 355,939 $ (1,412 ) $ 12,493 $ (493 ) $ 368,432 $ (1,905 ) December 31, 2019 U.S. Government agency obligations $ 6,585 $ (105 ) $ 12,886 $ (602 ) $ 19,471 $ (707 ) Obligations of states and political subdivisions — — 6,216 (53 ) 6,216 (53 ) Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 23,544 (107 ) 18,529 (272 ) 42,073 (379 ) Issued by FNMA and FHLMC 112,879 (230 ) 278,120 (3,305 ) 390,999 (3,535 ) Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 158,341 (738 ) 151,271 (1,631 ) 309,612 (2,369 ) Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 51,312 (167 ) 14,155 (121 ) 65,467 (288 ) Total $ 352,661 $ (1,347 ) $ 481,177 $ (5,984 ) $ 833,838 $ (7,331 ) 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. Prior to the adoption of FASB ASU 2016-13, Trustmark did not consider these investments to be other-than-temporarily impaired at December 31, 2019. There were no other-than-temporary impairments for the years ended December 31, 2019 and 2018. Security Gains and Losses For the years ended December 31, 2020, 2019 and 2018, there were no gross realized gains or losses as a result of calls and dispositions of securities. Realized gains and losses are determined using the specific identification method and are included in noninterest income as security gains (losses), net. Securities Pledged Securities with a carrying value of $1.964 billion and $1.770 billion at December 31, 2020 and 2019, respectively, were pledged to collateralize public deposits and securities sold under repurchase agreements and for other purposes as permitted by law. At both December 31, 2020 and 2019, none of these securities were pledged under the Federal Reserve Discount Window program to provide additional contingency funding capacity. Contractual Maturities The amortized cost and estimated fair value of securities available for sale and held to maturity at December 31, 2020, by contractual maturity, are shown below ($ 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 $ 1,570 $ 1,604 $ 19,237 $ 19,374 Due after one year through five years 1,527 1,570 7,347 7,465 Due after five years through ten years 2,031 1,989 — — Due after ten years 18,448 18,713 — — 23,576 23,876 26,584 26,839 Mortgage-backed securities 1,936,197 1,967,939 511,488 536,276 Total $ 1,959,773 $ 1,991,815 $ 538,072 $ 563,115

Loans Held for Investment (LHFI

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI	12 Months Ended
	Dec. 31, 2020
Accounts Notes Loans And Financing Receivable Gross Allowance And Net [Abstract]
Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI	Note 4 – LHFI and Allowance for Credit Losses, LHFI Trustmark adopted FASB ASC Topic 326 in accordance with the amendments of FASB ASU 2016-13 on January 1, 2020. In accordance with FASB ASC Subtopic 326-20, Trustmark has developed an ACL methodology effective January 1, 2020, which replaces its previous allowance for loan losses methodology. See the section captioned “ACL, LHFI” within this note for additional information regarding Trustmark’s ACL. Trustmark adopted FASB ASC Topic 326 using the modified retrospective approach prescribed by the amendments of ASU 2016-13; therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation. At December 31, 2020 and 2019, LHFI consisted of the following ($ in thousands): December 31, 2020 2019 Loans secured by real estate: Construction, land development and other land (1) $ 514,056 $ 1,162,791 Other secured by 1-4 family residential properties (1) 524,732 1,855,913 Secured by nonfarm, nonresidential properties 2,709,026 2,475,245 Other real estate secured 1,065,964 724,480 Other loans secured by real estate: (1) Other construction 794,983 — Secured by 1-4 family residential properties 1,216,400 — Commercial and industrial loans 1,309,078 1,477,896 Consumer loans 164,386 175,738 State and other political subdivision loans 1,000,776 967,944 Other commercial loans (1) 525,123 495,621 LHFI 9,824,524 9,335,628 Less ACL 117,306 84,277 Net LHFI $ 9,707,218 $ 9,251,351 (1) In accordance with the guidance in FASB ASC Topic 326, Trustmark redefined its LHFI portfolio segments and related loan classes based on the level at which risk is monitored within the ACL methodology. The other loans secured by real estate portfolio segment and related loan classes were separated from the loans secured by real estate portfolio segment. The other construction loans were segregated from the construction, land development and other land loans. The other loans secured by 1-4 family residential properties were segregated from the loans secured by 1-4 family residential properties and the loans secured by 1-4 family residential properties were redefined in the other loans secured by real estate portfolio segment. Other loans were redefined as other commercial loans. Accrued interest receivable is not included in the amortized cost basis of Trustmark’s LHFI. At December 31, 2020, accrued interest receivable for LHFI totaled $33.0 million with no related ACL and was reported in other assets on the accompanying consolidated balance sheet. 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, 2020, 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, 2020 and 2019, loans to certain executive officers and directors, including their immediate families and companies in which they are principal owners, totaled $37.7 million and $35.5 million, respectively. During 2020, $470.4 million of new loan advances were made, while repayments were $468.2 million. There were no increases in loans due to changes in executive officers and directors. Nonaccrual and Past Due LHFI No material interest income was recognized in the income statement on nonaccrual LHFI for each of the years in the three-year period ended December 31, 2020. The following table provides the amortized cost basis of loans on nonaccrual status and loans past due 90 days or more still accruing interest as of December 31, 2020 ($ in thousands): December 31, 2020 Nonaccrual With No ACL Total Nonaccrual Loans Past Due 90 Days or More Still Accruing Loans secured by real estate: Construction, land development and other land $ 5,756 $ 5,985 $ — Other secured by 1-4 family residential properties 1,895 4,487 79 Secured by nonfarm, nonresidential properties 12,037 15,197 — Other real estate secured 60 185 — Other loans secured by real estate: Other construction — — — Secured by 1-4 family residential properties — 11,807 1,257 Commercial and industrial loans 12,665 15,618 — Consumer loans — 86 240 State and other political subdivision loans — 3,970 — Other commercial loans — 5,793 — Total $ 32,413 $ 63,128 $ 1,576 The following table provides an aging analysis of the amortized cost basis of past due LHFI at December 31, 2020 ($ in thousands): December 31, 2020 Past Due 90 Days Total Past Current 30-59 Days 60-89 Days or More Due Loans Total Loans secured by real estate: Construction, land development and other land $ 339 $ 34 $ 161 $ 534 $ 513,522 $ 514,056 Other secured by 1-4 family residential properties 1,505 523 896 2,924 521,808 524,732 Secured by nonfarm, nonresidential properties 920 — 972 1,892 2,707,134 2,709,026 Other real estate secured 103 101 107 311 1,065,653 1,065,964 Other loans secured by real estate: Other construction — — — — 794,983 794,983 Secured by 1-4 family residential properties 3,291 1,289 5,110 9,690 1,206,710 1,216,400 Commercial and industrial loans 271 196 1,543 2,010 1,307,068 1,309,078 Consumer loans 926 190 240 1,356 163,030 164,386 State and other political subdivision loans 117 — 177 294 1,000,482 1,000,776 Other commercial loans 2,143 2,971 346 5,460 519,663 525,123 Total $ 9,615 $ 5,304 $ 9,552 $ 24,471 $ 9,800,053 $ 9,824,524 The following table provides an aging analysis of past due and nonaccrual LHFI by loan class at December 31, 2019 ($ in thousands): December 31, 2019 Past Due 90 Days Current 30-59 Days 60-89 Days or More (1) Total Nonaccrual Loans Total Loans secured by real estate: Construction, land development and other land $ 380 $ 256 $ — $ 636 $ 897 $ 1,161,258 $ 1,162,791 Secured by 1-4 family residential properties 5,254 940 211 6,405 16,810 1,832,698 1,855,913 Secured by nonfarm, nonresidential properties 1,698 — — 1,698 7,700 2,465,847 2,475,245 Other real estate secured 8 — — 8 1,032 723,440 724,480 Commercial and industrial loans 617 12 39 668 21,775 1,455,453 1,477,896 Consumer loans 2,208 380 392 2,980 108 172,650 175,738 State and other political subdivision loans 76 — — 76 4,079 963,789 967,944 Other loans 152 4 — 156 825 494,640 495,621 Total $ 10,393 $ 1,592 $ 642 $ 12,627 $ 53,226 $ 9,269,775 $ 9,335,628 (1) Past due 90 days or more but still accruing interest. Impaired LHFI Prior to the adoption of FASB ASC Topic 326, Trustmark’s individually evaluated impaired LHFI include all commercial nonaccrual relationships of $500 thousand or more, which were specifically reviewed for impairment and deemed impaired, and all LHFI classified as TDRs in accordance with FASB ASC Subtopic 310-10-50-20, “Impaired Loans.” Once a LHFI was deemed to be impaired, the full difference between the book value and the most likely estimate of the collateral’s net realizable value was charged off or a specific reserve was established. No material interest income was recognized in the accompanying consolidated statements of income on impaired LHFI for each of the years ended December 31, 2019 and 2018. At December 31, 2019, individually evaluated impaired LHFI consisted of the following ($ in thousands): December 31, 2019 LHFI Unpaid Wit h o With an Total Average Principal Allowance Allowance Carrying Related Recorded Balance Recorded Recorded Amount Allowance Investment Loans secured by real estate: Construction, land development and other land $ 926 $ 610 $ 16 $ 626 $ — $ 1,089 Secured by 1-4 family residential properties 6,513 2,104 3,360 5,464 35 4,713 Secured by nonfarm, nonresidential properties 7,295 1,462 5,255 6,717 2,355 8,096 Other real estate secured 69 — 68 68 — 158 Commercial and industrial loans 27,178 19,374 4,084 23,458 707 27,088 Consumer loans 22 — 21 21 — 11 State and other political subdivision loans 4,079 — 4,079 4,079 1,809 6,337 Other loans 1,207 — 784 784 553 1,033 Total $ 47,289 $ 23,550 $ 17,667 $ 41,217 $ 5,459 $ 48,525 Troubled Debt Restructurings At December 31, 2020, 2019 and 2018, LHFI classified as TDRs totaled $25.8 million, $31.5 million and $28.2 million, respectively, At December 31, 2020, LHFI classified as TDRs were primarily comprised of credits with interest-only payments for an extended period of time, payment concessions and credits renewed at a rate that was not commensurate with that of new debt with similar risk which totaled $17.7 million. At December 31, 2019 and 2018, LHFI classified as TDRs were primarily comprised of credits with interest-only payments for an extended period of time and credits renewed at a rate that was not commensurate with that of new debt with similar risk which totaled $20.8 million and $23.8 million, respectively. The remaining TDRs at December 31, 2020, 2019 and 2018 resulted from bankruptcies or from payment or maturity extensions. Trustmark had $4.5 million of unused commitments on TDRs at December 31, 2020, compared to $7.0 million of unused commitments on TDRs at December 31, 2019 and $4.4 million of unused commitments on TDRs at December 31, 2018. At December 31, 2020, TDRs had a related ACL of $2.4 million, compared to related loan loss allowance of $3.2 million at December 31, 2019 and $2.3 million at December 31, 2018. Specific charge-offs related to TDRs totaled $2.3 million, $1.6 million and $18.4 million for the years ended December 31, 2020, 2019 and 2018, respectively. The following tables illustrate the impact of modifications classified as TDRs for the periods presented ($ in thousands): Year Ended December 31, 2020 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Other secured by 1-4 family residential properties 13 $ 923 $ 929 Secured by nonfarm, nonresidential properties 2 1,111 1,111 Commercial and industrial loans 4 1,665 1,664 Consumer loans 6 26 26 State and other political subdivision loans 2 3,902 3,872 Total 27 $ 7,627 $ 7,602 Year Ended December 31, 2019 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Secured by 1-4 family residential properties 19 $ 1,742 $ 1,738 Secured by nonfarm, nonresidential properties 1 5,055 5,055 Commercial and industrial loans 8 9,167 9,054 Consumer loans 2 30 30 Total 30 $ 15,994 $ 15,877 Year Ended December 31, 2018 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Construction, land development and other land 1 $ 22 $ 22 Secured by 1-4 family residential properties 23 2,102 1,660 Secured by nonfarm, nonresidential properties 2 1,780 1,780 Commercial and industrial loans 23 26,970 25,862 Consumer loans 3 4 4 Total 52 $ 30,878 $ 29,328 The table below includes the balances at default for TDRs modified within the last 12 months for which there was a payment default during the periods presented ($ in thousands): Years Ended December 31, 2020 2019 2018 TDRs that Subsequently Defaulted Number of Contracts Recorded Investment Number of Contracts Recorded Investment Number of Contracts Recorded Investment Loans secured by real estate: Construction, land development and other land — $ — — $ — 1 $ 22 Other secured by 1-4 family residential properties 2 78 3 446 5 734 Secured by nonfarm, nonresidential properties 1 139 — — — — Commercial and industrial loans 1 82 7 192 6 15,178 Consumer loans — — 1 27 1 1 Total 4 $ 299 11 $ 665 13 $ 15,935 Trustmark’s TDRs have resulted primarily from allowing the borrower to pay interest-only for an extended period of time and credits renewed at a rate that was not commensurate with that of new debt with similar risk rather than from forgiveness. Accordingly, as shown above, these TDRs have a similar recorded investment for both the pre-modification and post-modification disclosure. Trustmark has utilized loans 90 days or more past due to define payment default in determining TDRs that have subsequently defaulted. The following tables detail LHFI classified as TDRs by loan class at December 31, 2020, 2019 and 2018 ($ in thousands): December 31, 2020 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 12 $ 12 Other secured by 1-4 family residential properties — 3,699 3,699 Secured by nonfarm, nonresidential properties — 3,903 3,903 Commercial and industrial loans 1,500 12,749 14,249 Consumer loans 6 17 23 State and other political subdivision loans — 3,793 3,793 Other commercial loans — 81 81 Total TDRs $ 1,506 $ 24,254 $ 25,760 December 31, 2019 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 15 $ 15 Secured by 1-4 family residential properties 77 3,865 3,942 Secured by nonfarm, nonresidential properties — 5,176 5,176 Commercial and industrial loans 3,319 18,913 22,232 Consumer loans — 21 21 Other loans — 137 137 Total TDRs $ 3,396 $ 28,127 $ 31,523 December 31, 2018 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 24 $ 24 Secured by 1-4 family residential properties 743 3,125 3,868 Secured by nonfarm, nonresidential properties 1,734 395 2,129 Commercial and industrial loans 9,007 12,620 21,627 Consumer loans — 2 2 Other loans — 540 540 Total TDRs $ 11,484 $ 16,706 $ 28,190 On March 27, 2020, the CARES Act, a stimulus package intended to provide relief to businesses and consumers in the United States struggling as a result of the pandemic, was signed into law. Section 4013 of the CARES Act also addressed COVID-19 related modifications and specified that COVID-19 related modifications executed between March 1, 2020 and the earlier of (i) 60 days after the date of termination of the national emergency declared by the President and (ii) January 1, 2022, on loans that were current as of December 31, 2019 are not TDRs. Additionally, under guidance from the federal banking agencies, other short-term modifications made on a good faith basis in response to COVID-19 to borrowers that were current prior to any relief are not TDRs under ASC Subtopic 310-40. These modifications include short-term (e.g., up to six months) modifications such as payment deferrals, fee waivers, extensions of repayment terms, or delays in payment that are insignificant. Borrowers considered current are those that are less than 30 days past due on their contractual payments at the time a modification program is implemented. Trustmark modified 2,923 individual loans with aggregate principal balances totaling $1.271 billion through December 31, 2020. Of these modifications, $972 thousand were treated as TDRs. Commercial concessions were primarily either interest only for 90 days or full payment deferrals for 90 days. Consumer concessions were 90-day full payment deferrals. At December 31, 2020, the balance of loans remaining under some type of concession totaled $34.2 million. Collateral-Dependent Loans The following table presents the amortized cost basis of collateral-dependent loans by class of loans and collateral type as of December 31, 2020 ($ in thousands): December 31, 2020 Real Estate Equipment and Machinery Inventory and Receivables Vehicles Miscellaneous Total Loans secured by real estate: Construction, land development and other land $ 5,756 $ — $ — $ — $ — $ 5,756 Other secured by 1-4 family residential properties 454 — — — — 454 Secured by nonfarm, nonresidential properties 12,037 — — — — 12,037 Other real estate secured 60 — — — — 60 Other loans secured by real estate: Other construction — — — — — — Secured by 1-4 family residential properties 1,441 — — — — 1,441 Commercial and industrial loans 86 425 4,899 135 8,531 14,076 Consumer loans — — — — — — State and other political subdivision loans 3,970 — — — — 3,970 Other commercial loans 606 — 1,958 — 3,051 5,615 Total $ 24,410 $ 425 $ 6,857 $ 135 $ 11,582 $ 43,409 A loan is collateral dependent when the borrower is experiencing financial difficulty and repayment of the loan is expected to be provided substantially through the sale of the collateral. The following provides a qualitative description by class of loan of the collateral that secures Trustmark’s collateral-dependent LHFI: • Loans secured by real estate – Loans within these loan classes are secured by liens on real estate properties. One loan relationship experienced a decline in fair value due to general deterioration during the fourth quarter of 2020 to the collateral that secures the relationship. There have been no other significant changes to the collateral that secures these financial assets during the period. • Other loans secured by real estate – Loans within these loan classes are secured by liens on real estate properties. There have been no significant changes to the collateral that secures these financial assets during the period. • Commercial and industrial loans – Loans within this loan class are primarily secured by inventory, accounts receivables, equipment and other non-real estate collateral. There have been no significant changes to the collateral that secures these financial assets during the period. • State and other political subdivision loans – Loans within this loan class are secured by liens on real estate properties. There have been no significant changes to the collateral that secures these financial assets during the period. • Other commercial loans - Loans within this loan class are secured by liens on real estate properties or priority status of a UCC agreement for non-real estate collateral. There have been no significant changes to the collateral that secures these financial assets during the period. 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 segment 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 portfolio segment. • 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 portfolio segment. 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. To enhance this process, Trustmark has determined that loans will be individually assessed, and a formal analysis will be performed and based upon the analysis the loan will be written down to net realizable value. Trustmark will individually assess and remove loans from the pool in the following circumstances: • Commercial nonaccrual loans with total exposure of $500 thousand (excluding those portions of the debt that are government guaranteed or are secured by Trustmark deposits or marketable securities) or more. • Any loan that is believed to not share similar risk characteristics with the rest of the pool will be individually assessed. Otherwise, the loan will be left within the pool based on the results of the assessment. • Commercial accruing loans deemed to be a TDR with total exposure of $500 thousand (excluding those portions of the debt that are government guaranteed or are secured by Trustmark deposits or marketable securities) or more. If the loan is believed to not share similar risk characteristics with the rest of the loan pool, the loan will be individually assessed. Otherwise, the loan will be left within the pool and monitored on an ongoing basis. 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 class as well as the adherence to Trustmark’s loan policy and the loan administration process. 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 $100 thousand or more. In addition, periodic reviews of significant development, commercial construction, multi-family and nonowner-occupied projects are performed. These reviews assess each particular project with respect to location, project valuations, progress of completion, leasing status, current financial information, rents, operating expenses, cash flow, adherence to budget and projections and other information as applicable. Summary results are reviewed by Senior and Regional Credit Officers in addition to the Chief Credit Officer with a determination made as to the appropriateness of existing risk ratings and accrual status. Consumer Credits Consumer LHFI that do not meet a minimum custom credit score are reviewed quarterly by Management. The Retail Credit Review Committee reviews the volume and percentage of approvals that did not meet the minimum passing custom score by region, individual location, and officer to ensure that Trustmark continues to originate quality loans. Trustmark monitors the levels and severity of past due consumer LHFI on a daily basis through its collection activities. A detailed assessment of consumer LHFI delinquencies is performed monthly at both a product and market level by delivery channel, which incorporates the perceived level of risk at time of underwriting. The tables below present the amortized cost basis of loans by credit quality indicator and class of loans based on the most recent analysis performed ($ in thousands): Term Loans by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Total As of December 31, 2020 Commercial LHFI Loans secured by real estate: Construction, land development and other land: Pass - RR 1 through RR 6 $ 287,218 $ 62,078 $ 26,401 $ 4,487 $ 3,274 $ 3,564 $ 28,548 $ 415,570 Special Mention - RR 7 — — — — — — — — Substandard - RR 8 5,419 4,363 1,226 12 494 22 101 11,637 Doubtful - RR 9 — — — — — 42 — 42 Total 292,637 66,441 27,627 4,499 3,768 3,628 28,649 427,249 Other secured by 1-4 family residential properties: Pass - RR 1 through RR 6 $ 35,139 $ 19,596 $ 15,399 $ 9,605 $ 10,273 $ 4,786 $ 8,486 $ 103,284 Special Mention - RR 7 255 — 50 — — — — 305 Substandard - RR 8 1,155 8 914 341 302 337 3,950 7,007 Doubtful - RR 9 29 — — — — — — 29 Total 36,578 19,604 16,363 9,946 10,575 5,123 12,436 110,625 Secured by nonfarm, nonresidential properties: Pass - RR 1 through RR 6 $ 697,439 $ 496,476 $ 442,264 $ 293,072 $ 254,747 $ 251,219 $ 96,098 $ 2,531,315 Special Mention - RR 7 13,452 6,139 2,956 4,466 4,957 20,545 — 52,515 Substandard - RR 8 19,119 20,572 4,516 12,956 38,956 25,438 2,779 124,336 Doubtful - RR 9 52 163 — — 217 306 — 738 Total 730,062 523,350 449,736 310,494 298,877 297,508 98,877 2,708,904 Other real estate secured: Pass - RR 1 through RR 6 $ 146,803 $ 376,765 $ 347,472 $ 48,626 $ 89,824 $ 23,680 $ 12,116 $ 1,045,286 Special Mention - RR 7 — — — — — 841 — 841 Substandard - RR 8 18,649 14 18 — 556 122 — 19,359 Doubtful - RR 9 — — — — — — — — Total 165,452 376,779 347,490 48,626 90,380 24,643 12,116 1,065,486 Term Loans by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Total As of December 31, 2020 Commercial LHFI Other loans secured by real estate: Other construction Pass - RR 1 through RR 6 $ 262,544 $ 425,936 $ 81,476 $ 14,074 $ 2,464 $ — $ 7,735 $ 794,229 Special Mention - RR 7 — — — — — — — — Substandard - RR 8 754 — — — — — — 754 Doubtful - RR 9 — — — — — — — — Total 263,298 425,936 81,476 14,074 2,464 — 7,735 794,983 Commercial and industrial loans: Pass - RR 1 through RR 6 $ 444,304 $ 165,163 $ 77,611 $ 77,985 $ 59,131 $ 43,214 $ 372,486 $ 1,239,894 Special Mention - RR 7 677 45 — — — — 240 962 Substandard - RR 8 12,090 1,814 9,737 3,735 2,160 5,024 33,380 67,940 Doubtful - RR 9 151 95 — — 32 4 — 282 Total 457,222 167,117 87,348 81,720 61,323 48,242 406,106 1,309,078 State and other political subdivision loans: Pass - RR 1 through RR 6 $ 250,363 $ 79,595 $ 41,334 $ 113,817 $ 132,634 $ 372,831 $ 1,446 $ 992,020 Special Mention - RR 7 — — — — — 4,018 — 4,018 Substandard - RR 8 — — — 247 — 4,491 — 4,738 Doubtful - RR 9 — — — — — — — — Total 250,363 79,595 41,334 114,064 132,634 381,340 1,446 1,000,776 Other commercial loans: Pass - RR 1 through RR 6 $ 101,230 $ 70,990 $ 20,769 $ 9,723 $ 33,481 $ 30,715 $ 225,533 $ 492,441 Special Mention - RR 7 7,500 — — — — — 11,333 18,833 Substandard - RR 8 381 2,099 683 6 707 — 9,948 13,824 Doubtful - RR 9 2 — — — — 23 — 25 Total 109,113 73,089 21,452 9,729 34,188 30,738 246,814 525,123 Total commercial LHFI $ 2,304,725 $ 1,731,911 $ 1,072,826 $ 593,152 $ 634,209 $ 791,222 $ 814,179 $ 7,942,224 Term Loans by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Total As of December 31, 2020 Consumer LHFI Loans secured by real estate: Construction, land development and other land: Current $ 47,336 $ 24,174 $ 8,496 $ 2,036 $ 1,447 $ 2,868 $ — $ 86,357 Past due 30-89 days — 318 20 — 1 12 — 351 Past due 90 days or more — — — — — — — — Nonaccrual — — — — — 99 — 99 Total 47,336 24,492 8,516 2,036 1,448 2,979 — 86,807 Other secured by 1-4 family residential properties: Current $ 20,864 $ 10,253 $ 12,037 $ 4,177 $ 2,082 $ 11,124 $ 348,830 $ 409,367 Past due 30-89 days 93 12 — 13 — 133 1,058 1,309 Past due 90 days or more — — — — — 30 22 52 Nonaccrual 6 44 121 428 — 382 2,398 3,379 Total 20,963 10,309 12,158 4,618 2,082 11,669 352,308 414,107 Secured by nonfarm, nonresidential properties: Current $ 109 $ — $ — $ 4 $ — $ 9 $ — $ 122 Past due 30-89 days — — — — — — — — Past due 90 days or more — — — — — — — — Nonaccrual — — — — — — — — Total 109 — — 4 — 9 — 122 Other real estate secured: Current $ 107 $ — $ 38 $ 37 $ 96 $ 200 $ — $ 478 Past due 30-89 days — — — — — — — — Past due 90 days or more — — — — — — — — Nonaccrual — — — — — — — — Total 107 — 38 37 96 200 — 478 Term Loans by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Total As of December 31, 2020 Consumer LHFI Other loans secured by real estate: Secured by 1-4 family residential properties Current $ 289,521 $ 214,056 $ 173,324 $ 92,564 $ 109,031 $ 321,250 $ — $ 1,199,746 Past due 30-89 days 499 93 753 366 1,080 799 — 3,590 Past due 90 days or more 159 214 208 127 — 549 — 1,257 Nonaccrual 283 711 2,024 682 239 7,868 — 11,807 Total 290,462 215,074 176,309 93,739 110,350 330,466 — 1,216,400 Consumer loans: Current $ 65,370 $ 25,303 $ 13,140 $ 3,893 $ 1,257 $ 345 $ 53,669 $ 162,977 Past due 30-89 days 524 158 67 19 7 3 305 1,083 Past due 90 days or more 77 — 4 — — — 159 240 Nonaccrual 12 4 55 13 2 — — 86 Total 65,983 25,465 13,266 3,925 1,266 348 54,133 164,386 Total consumer LHFI $ 424,960 $ 275,340 $ 210,287 $ 104,359 $ 115,242 $ 345,671 $ 406,441 $ 1,882,300 Total LHFI $ 2,729,685 $ 2,007,251 $ 1,283,113 $ 697,511 $ 749,451 $ 1,136,893 $ 1,220,620 $ 9,824,524 The tables below present LHFI by loan class and credit quality indicator at December 31, 2019 ($ in thousands): December 31, 2019 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 $ 1,075,146 $ — $ 15,726 $ 42 $ 1,090,914 Secured by 1-4 family residential properties 116,592 45 6,355 41 123,033 Secured by nonfarm, nonresidential properties 2,430,761 — 44,001 328 2,475,090 Other real es

Acquired Loans

Acquired Loans	12 Months Ended
	Dec. 31, 2020
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities [Abstract]
Acquired Loans	Note 5 – 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. Upon adoption of FASB ASC Topic 326, which was effective for Trustmark on January 1, 2020 in accordance with the amendments in FASB ASU 2016-13, Trustmark elected to account for its existing acquired loans as purchased credit deteriorated (PCD) loans included within the LHFI portfolio. Trustmark elected to maintain pools of loans that were previously accounted for under FASB ASC Subtopic 310-30, “Receivables – Loans and Debt Securities Acquired with Deteriorated Credit Quality,” and will continue to account for these pools as a unit of account. Loans are only removed from the existing loan pools if they are written off, paid off or sold. Upon adoption of FASB ASC Topic 326, the ACL was determined for each pool and added to the pool’s carrying value to establish a new amortized cost basis. The difference between the unpaid principal balance of the pool and the new amortized cost basis is the noncredit premium or discount which will be amortized into interest income over the remaining life of the pool. Changes to the allowance for credit losses after adoption of FASB ASC Topic 326 are recorded through the PCL. Consequently, acquired loans of $72.6 million, as well as the allowance for loan losses, acquired loans of $815 thousand, were transferred on January 1, 2020. At December 31, 2019, acquired loans consisted of the following ($ in thousands): December 31, 2019 Loans secured by real estate: Construction, land development and other land $ 4,771 Secured by 1-4 family residential properties 17,525 Secured by nonfarm, nonresidential properties 38,206 Other real estate secured 3,946 Commercial and industrial loans 5,035 Consumer loans 520 Other loans 2,598 Acquired loans 72,601 Less allowance for loan losses, acquired loans 815 Net acquired loans $ 71,786 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, 2019 $ 102,890 $ 2,811 Transfers (2) — (2,926 ) Accretion to interest income 5,532 115 Payments received, net (37,230 ) — Other (3) 178 — Change in allowance for loan losses, acquired loans 416 — Carrying value, net at December 31, 2019 71,786 — FASB ASU 2016-13 adoption adjustment (71,786 ) — Carrying value, net at December 31, 2020 $ — $ — (1) “Acquired Not ASC 310-30” loans consist of loans that are not in scope for FASB ASC Subtopic 310-30. (2) “Acquired Not ASC 310-30” loans transferred to LHFI due to the discount on these loans being fully amortized. ( 3 ) Includes miscellaneous timing adjustments as well as acquired loan terminations through foreclosure, charge-off and other terminations. Under FASB ASC Subtopic 310-30, the accretable yield is the excess of expected cash flows at acquisition over the initial fair value of acquired impaired loans and is recorded as interest income over the estimated life of the loans using the effective yield method if the timing and amount of the future cash flows is reasonably estimable. The following table presents changes in the accretable yield for the periods presented ($ in thousands): Years Ended December 31, 2020 2019 2018 Accretable yield at beginning of period $ (14,816 ) $ (17,722 ) $ (31,426 ) FASB ASU 2016-13 adoption adjustment 14,816 — — Accretion to interest income — 5,532 9,514 Disposals, net — 2,072 3,926 Transfers (1) — — 5,874 Reclassification from nonaccretable difference (2) — (4,698 ) (5,610 ) Accretable yield at end of period $ — $ (14,816 ) $ (17,722 ) (1) During 2018, Trustmark transferred the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions from acquired impaired loans to LHFI. ( 2 ) Reclassifications from nonaccretable difference are due to lower loss expectations and improvements in expected cash flows. The following table presents the components of the allowance for loan losses on acquired impaired loans for the periods presented ($ in thousands): Years Ended December 31, 2020 2019 2018 Balance at beginning of period $ 815 $ 1,231 $ 4,079 FASB ASU 2016-13 adoption adjustment (815 ) — — Transfers (1) — — (1,554 ) Net (charge-offs) recoveries — (458 ) (289 ) Provision for loan losses, acquired loans — 42 (1,005 ) Balance at end of period $ — $ 815 $ 1,231 (1) The allowance for loan losses balance related to the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisition s , which were transferred from acquired impaired loans to LHFI during 2018. The table below presents the acquired loans by loan class and credit quality indicator at December 31, 2019 ($ in thousands): December 31, 2019 Commercial Loans Pass - Special Mention - Substandard - Doubtful - Categories 1-6 Category 7 Category 8 Category 9 Subtotal Loans secured by real estate: Construction, land development and other land $ 4,022 $ — $ 192 $ — $ 4,214 Secured by 1-4 family residential properties 3,164 42 580 — 3,786 Secured by nonfarm, nonresidential properties 27,848 — 9,972 386 38,206 Other real estate secured 3,878 — 68 — 3,946 Commercial and industrial loans 3,419 — — 1,616 5,035 Consumer loans — — — — — Other loans 2,591 — 7 — 2,598 Total acquired loans $ 44,922 $ 42 $ 10,819 $ 2,002 $ 57,785 Consumer Loans Past Due Past Due Total Current 30-89 Days 90 Days or More Nonaccrual (1) Subtotal Acquired Loans Loans secured by real estate: Construction, land development and other land $ 463 $ 94 $ — $ — $ 557 $ 4,771 Secured by 1-4 family residential properties 12,843 615 281 — 13,739 17,525 Secured by nonfarm, nonresidential properties — — — — — 38,206 Other real estate secured — — — — — 3,946 Commercial and industrial loans — — — — — 5,035 Consumer loans 489 31 — — 520 520 Other loans — — — — — 2,598 Total acquired loans $ 13,795 $ 740 $ 281 $ — $ 14,816 $ 72,601 (1) Acquired loans not accounted for under FASB ASC Subtopic 310-30 . The following table provides an aging analysis of contractually past due and nonaccrual acquired loans at December 31, 2019 ($ in thousands): December 31, 2019 Past Due 30-59 Days 60-89 Days 90 Days or More (1) Total Nonaccrual (2) Current Loans Total Acquired Loans Loans secured by real estate: Construction, land development and other land $ 94 $ — $ 38 $ 132 $ — $ 4,639 $ 4,771 Secured by 1-4 family residential properties 696 131 366 1,193 — 16,332 17,525 Secured by nonfarm, nonresidential properties 36 — 851 887 — 37,319 38,206 Other real estate secured 1 — 52 53 — 3,893 3,946 Commercial and industrial loans — — — — — 5,035 5,035 Consumer loans 16 15 — 31 — 489 520 Other loans — — — — — 2,598 2,598 Total acquired loans $ 843 $ 146 $ 1,307 $ 2,296 $ — $ 70,305 $ 72,601 (1) Past due 90 days or more but still accruing interest. (2) Acquired loans not accounted for under FASB ASC Subtopic 310-30.

Premises and Equipment, Net

Premises and Equipment, Net	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Premises and Equipment, Net	Note 6 – Premises and Equipment, Net At December 31, 2020 and 2019, premises and equipment, net consisted of the following ($ in thousands): December 31, 2020 2019 Land $ 52,189 $ 52,454 Buildings and leasehold improvements 216,650 210,362 Furniture and equipment 180,976 174,257 Total cost of premises and equipment 449,815 437,073 Less accumulated depreciation and amortization 263,147 256,608 Premises and equipment, net 186,668 180,465 Finance lease right-of-use assets 7,471 9,326 Assets held for sale 139 — Total premises and equipment, net $ 194,278 $ 189,791 Assets held for sale consisted of one property at December 31, 2020 compared to none at December 31, 2019. This property was transferred from premises and equipment, net to assets held for sale due to Trustmark’s intent to sell this property over the next twelve months as a result of its strategic initiatives. Property valuation adjustments of $1.7 million were recognized and included in other expense for 2020 compared to none for 2019 and $173 thousand for 2018, respectively. Depreciation and amortization of premises and equipment totaled $14.8 million in 2020, $15.7 million in 2019 and $14.3 million in 2018.

Mortgage Banking

Mortgage Banking	12 Months Ended
	Dec. 31, 2020
Mortgage Banking [Abstract]
Mortgage Banking	Note 7 – 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, 2020 2019 Balance at beginning of period $ 79,394 $ 95,596 Origination of servicing assets 29,805 16,711 Change in fair value: Due to market changes (26,147 ) (21,078 ) Due to runoff (16,588 ) (11,835 ) Balance at end of period $ 66,464 $ 79,394 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, 2020, the fair value of the MSR included an assumed average prepayment speed of 15 CPR and an average discount rate of 9.53% compared to an assumed average prepayment speed of 11 CPR and an average discount rate of 10.03% at December 31, 2019. 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 2020, 2019 and 2018, Trustmark sold $2.532 billion, $1.404 billion and $1.092 billion, respectively, of residential mortgage loans. Gain on sales of loans, net totaled $110.9 million in 2020, $30.3 million in 2019 and $21.8 million in 2018. Trustmark receives annual servicing fee income approximating 0.31% of the outstanding balance of the underlying loans, which totaled $23.3 million in 2020, $22.6 million in 2019 and $21.9 million in 2018. The gains on the sale of residential mortgage loans and the annual servicing fee are both recorded to noninterest income in mortgage banking, net in the accompanying consolidated statements of income. The investors and the securitization trusts have no recourse to the assets of Trustmark for failure of debtors to pay when due. The table below details the mortgage loans sold and serviced for others at December 31, 2020 and 2019 ($ in thousands): December 31, 2020 2019 Federal National Mortgage Association $ 4,629,670 $ 4,411,914 Government National Mortgage Association 2,960,760 2,652,782 Federal Home Loan Mortgage Corporation 50,459 73,134 Other 16,201 19,404 Total mortgage loans sold and serviced for others $ 7,657,090 $ 7,157,234 Trustmark is subject to losses in its loan servicing portfolio due to loan foreclosures. Trustmark has obligations to either repurchase the outstanding principal balance of a loan or make the purchaser whole for the economic benefits of a loan if it is determined that the loan sold was in violation of representations or warranties made by Trustmark at the time of the sale, herein referred to as mortgage loan servicing putback expenses. Such representations and warranties typically include those made regarding loans that had missing or insufficient file documentation, loans that do not meet investor guidelines, loans in which the appraisal does not support the value and/or loans obtained through fraud by the borrowers or other third parties. Generally, putback requests may be made until the loan is paid in full. However, mortgage loans delivered to Federal National Mortgage Association (FNMA) and Federal Home Loan Mortgage Corporation (FHLMC) on or after January 1, 2013 are subject to the Lending and Selling Representations and Warranties Framework updated in May 2014, which provides certain instances in which FNMA and FHLMC will not exercise their remedies, including a putback request, for breaches of certain selling representations and warranties, such as payment history and quality control review. When a putback request is received, Trustmark evaluates the request and takes appropriate actions based on the nature of the request. Trustmark is required by FNMA and FHLMC to provide a response to putback requests within 60 days of the date of receipt. The total mortgage loan servicing putback expenses were included in other expense. At both December 31, 2020 and 2019, Trustmark had a reserve for mortgage loan servicing putback expenses of $500 thousand. 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, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Identifiable Intangible Assets	Note 8 – Goodwill and Identifiable Intangible Assets Goodwill The table below illustrates goodwill by segment for the years ended December 31, 2020 and 2019 ($ in thousands): General Banking Insurance Total Balance as of January 1, 2019 $ 334,603 $ 45,024 $ 379,627 Adjustment during 2019 — — — Balance as of December 31, 2019 334,603 45,024 379,627 Adjustment during 2020 — 5,643 5,643 Balance as of December 31, 2020 $ 334,603 $ 50,667 $ 385,270 Trustmark’s General Banking Segment delivers a full range of banking services to consumer, corporate, small and middle-market businesses through its extensive branch network. The Insurance Segment includes TNB’s wholly-owned retail insurance subsidiary that offers a diverse mix of insurance products and services. Trustmark performed goodwill impairment tests for the General Banking and Insurance Segments during 2020, 2019 and 2018. Based on these tests, Trustmark concluded that the fair value of both the General Banking and Insurance Segments exceeded the book value and no impairment charge was required. Identifiable Intangible Assets At December 31, 2020 and 2019, identifiable intangible assets consisted of the following ($ in thousands): December 31, 2020 December 31, 2019 Gross Accumulated Net Carrying Gross Carrying Accumulated Net Carrying Amount Amortization Amount Amount Amortization Amount Core deposit intangibles $ 87,674 $ 84,580 $ 3,094 $ 87,674 $ 82,096 $ 5,578 Insurance intangibles 17,272 13,159 4,113 14,171 12,655 1,516 Banking charters 1,325 1,142 183 1,325 1,076 249 Total $ 106,271 $ 98,881 $ 7,390 $ 103,170 $ 95,827 $ 7,343 Trustmark recorded $3.1 million of amortization of identifiable intangible assets in 2020, $4.1 million in 2019 and $5.2 million in 2018. Trustmark estimates that amortization expense for identifiable intangible assets will be $2.3 million in 2021, $1.4 million in 2022, $673 thousand in 2023, $471 thousand in 2024 and $403 thousand in 2025. Trustmark continually evaluates whether events and circumstances have occurred that indicate that identifiable intangible assets have become impaired. Measurement of any impairment of such identifiable intangible assets is based on the fair values of those assets. There were no impairment losses on identifiable intangible assets recorded during 2020, 2019 or 2018. The following table illustrates the carrying amounts and remaining weighted-average amortization periods of identifiable intangible assets as of December 31, 2020 ($ in thousands): Remaining Weighted- Average Net Carrying Amortization Amount Period in Core deposit intangibles $ 3,094 3.1 Insurance intangibles 4,113 17.0 Banking charters 183 2.7 Total $ 7,390 10.8

Other Real Estate

Other Real Estate	12 Months Ended
	Dec. 31, 2020
Other Real Estate And Foreclosed Assets [Abstract]
Other Real Estate	Note 9 – Other Real Estate At December 31, 2020, 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, 2020 2019 2018 Balance at beginning of period $ 29,248 $ 34,668 $ 43,228 Additions 635 8,598 12,115 Disposals (16,446 ) (11,474 ) (19,802 ) Write-downs (1,786 ) (2,544 ) (873 ) Balance at end of period $ 11,651 $ 29,248 $ 34,668 Gains (losses), net on the sale of other real estate included in other real estate expense $ 897 $ (291 ) $ 700 At December 31, 2020 and 2019, other real estate by type of property consisted of the following ($ in thousands): December 31, 2020 2019 Construction, land development and other land properties $ 3,857 $ 11,482 1-4 family residential properties 1,349 3,453 Nonfarm, nonresidential properties 6,445 14,313 Other real estate properties — — Total other real estate $ 11,651 $ 29,248 At December 31, 2020 and 2019, other real estate by geographic location consisted of the following ($ in thousands): December 31, 2020 2019 Alabama $ 3,271 $ 8,133 Florida — 5,877 Mississippi (1) 8,330 14,919 Tennessee (2) 50 319 Texas — — Total other real estate $ 11,651 $ 29,248 (1) Mississippi includes Central and Southern Mississippi Regions. (2) Tennessee includes Memphis, Tennessee and Northern Mississippi Regions. At December 31, 2020 and 2019, the balance of other real estate included $1.3 million and $3.5 million, respectively, of foreclosed residential real estate properties recorded as a result of obtaining physical possession of the

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	Note 10 – Leases The table below details the components of net lease cost for the periods presented ($ in thousands): Year Ended December 31, 2020 2019 Finance leases Amortization of right-of-use assets $ 1,856 $ 2,162 Interest on lease liabilities 254 307 Operating lease cost 5,188 5,183 Short-term lease cost 423 370 Variable lease cost 1,286 1,387 Sublease income (335 ) (331 ) Net lease cost $ 8,672 $ 9,078 The table below details the cash payments included in the measurement of lease liabilities during the periods presented ($ in thousands): Year Ended December 31, 2020 2019 Finance leases Operating cash flows included in operating activities $ 254 $ 307 Financing cash flows included in payments under finance lease obligations 1,715 1,964 Operating leases Operating cash flows (fixed payments) included in other operating activities, net 4,988 5,092 Operating cash flows (liability reduction) included in other operating activities, net 3,856 5,404 The table below details balance sheet information, as well as weighted-average lease terms and discount rates, for the periods presented ($ in thousands): Year Ended December 31, 2020 2019 Finance lease right-of-use assets, net of accumulated depreciation $ 7,471 $ 9,326 Finance lease liabilities 7,805 9,520 Operating lease right-of-use assets 30,901 31,182 Operating lease liabilities 32,290 32,354 Weighted-average lease term Finance leases 8.53 years 8.62 years Operating leases 8.65 years 9.05 years Weighted-average discount rate Finance leases 3.10 % 3.01 % Operating leases 3.41 % 3.51 % At December 31, 2020, future minimum rental commitments under finance and operating leases were as follows ($ in thousands): Finance Leases Operating Leases 2021 $ 1,615 $ 4,714 2022 1,556 4,456 2023 871 4,342 2024 572 4,449 2025 584 4,464 Thereafter 3,868 15,040 Total minimum lease payments 9,066 37,465 Less imputed interest (1,261 ) (5,175 ) Lease liabilities $ 7,805 $ 32,290

Deposits

Deposits	12 Months Ended
	Dec. 31, 2020
Deposits [Abstract]
Deposits	Note 11 – Deposits At December 31, 2020 and 2019, deposits consisted of the following ($ in thousands): December 2020 2019 Noninterest-bearing demand $ 4,349,010 $ 2,891,215 Interest-bearing demand 3,646,246 3,125,914 Savings 4,647,610 3,590,509 Time 1,405,898 1,637,919 Total $ 14,048,764 $ 11,245,557 Interest expense on deposits by type consisted of the following for the periods presented ($ in thousands): Years Ended December 31, 2020 2019 2018 Interest-bearing demand $ 9,985 $ 35,428 $ 18,479 Savings 13,481 19,462 17,980 Time 14,021 24,281 17,477 Total $ 37,487 $ 79,171 $ 53,936 Time deposits that exceed the FDIC insurance limit of $250 thousand totaled $228.1 million and $285.7 million at December 31, 2020 and 2019, respectively. The maturities of interest-bearing deposits at December 31, 2020, are as follows ($ in thousands): 2021 $ 1,152,489 2022 176,421 2023 46,750 2024 14,330 2025 12,738 Thereafter 3,170 Total time deposits 1,405,898 Interest-bearing deposits with no stated maturity 8,293,856 Total interest-bearing deposits $ 9,699,754

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2020
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 Subtopic 860-30, “Transfers and Servicing – Secured Borrowing and Collateral.” Securities sold under repurchase agreements are stated at the amount of cash received in connection with the transaction. Trustmark monitors collateral levels on a continual basis and may be required to provide additional collateral based on the fair value of the underlying securities. Securities sold under repurchase agreements are secured by securities with a carrying amount of $156.1 million and $105.6 million at December 31, 2020 and 2019, respectively. As of December 31, 2020, all repurchase agreements were short-term and consisted primarily of sweep repurchase arrangements, under which excess deposits are “swept” into overnight repurchase agreements with Trustmark. The following table presents the securities sold under repurchase agreements by collateral pledged at December 31, 2020 and 2019 ($ in thousands): December 31, 2020 2019 Mortgage-backed securities Residential mortgage pass-through securities Issued by FNMA and FHLMC $ 115,357 $ — Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 12,696 24,282 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA — 29,290 Total securities sold under repurchase agreements $ 128,053 $ 53,572 Other Borrowings At December 31, 2020 and 2019, other borrowings consisted of the following ($ in thousands): December 2020 2019 FHLB advances $ 741 $ 811 Serviced GNMA loans eligible for repurchase 141,160 57,062 Finance lease liabilities 7,805 9,520 Other 18,546 18,003 Total other borrowings $ 168,252 $ 85,396 FHLB Advances At December 31, 2020, Trustmark had one outstanding short-term FHLB advance totaling $625 thousand with the FHLB of Atlanta, compared to none at December 31, 2019. This advance was assumed through the BancTrust merger and had a fixed interest rate of 0.75%. At December 31, 2020, this advance had a remaining maturity of 181 days. Trustmark incurred $9 thousand of interest expense on short-term FHLB advances in 2020, compared to no interest expense in 2019 and $4.4 million of interest expense in 2018. At December 31, 2020, Trustmark had one outstanding long-term FHLB advance totaling $116 thousand with the FHLB of Atlanta, compared to two outstanding long-term FHLB advances totaling $811 thousand at December 31, 2019. This advance was assumed through the BancTrust merger and had a fixed interest rate of 0.08%. At December 31, 2020, this advance had a remaining maturity of 5.71 years. At December 31, 2019, the outstanding long-term advances had fixed interest rates of 0.08% and 0.75% with outstanding balances of $135 thousand and $676 thousand, respectively. At December 31, 2019, the outstanding long-term advances had a weighted-average remaining maturity of 2.37 years with a weighted-average cost of 0.64% during 2019. There was no fair market value adjustment associated with the BancTrust merger included in the FHLB advances at December 31, 2020 and 2019. Trustmark’s FHLB advances are collateralized by securities held in safekeeping with the FHLB of Atlanta. Trustmark incurred $8 thousand of interest expense on long-term FHLB advances in 2020, compared to $5 thousand of interest expense in 2019 and $6 thousand of interest expense in 2018. At both December 31, 2020 and 2019, Trustmark had no outstanding FHLB advances with the FHLB of Dallas. At December 31, 2020 and 2019, Trustmark had $2.725 billion and $3.178 billion, respectively, available in additional borrowing capacity from the FHLB of Dallas. Subordinated Notes During the fourth quarter of 2020, Trustmark agreed to issue and sell $125.0 million aggregate principal amount of its 3.625% Fixed-to-Floating Rate Subordinated Notes (the Notes) due December 1, 2030. The Notes were sold at an underwriting discount of 1.2%, resulting in net proceeds to Trustmark of $123.5 million before deducting offering expenses of $600 thousand. At December 31, 2020, the carrying amount of the Notes was $122.9 million. The Notes are unsecured obligations and are subordinated in right of payment to all of Trustmark’s existing and future senior indebtedness, whether secured or unsecured. The Notes are obligations of Trustmark only and are not obligations of, and are not guaranteed by, any of its subsidiaries, including TNB. From the date of issuance until November 30, 2025, the Notes bear interest at a fixed rate of 3.625% per year, payable semi-annually in arrears on June 1 and December 1 of each year. Beginning December 1, 2025, the Notes will bear interest at a floating rate per year equal to the Benchmark rate, which is the Three-Month Term Secured Overnight Financing Rate (SOFR), plus 338.7 basis points, payable quarterly in arrears on March 1, June 1, September 1 and December 1 of each year. The Notes qualify as Tier 2 capital for Trustmark. The Notes may be redeemed at Trustmark’s option under certain circumstances. Trustmark intends to use the net proceeds for general corporate purposes. Junior Subordinated Debt Securities On August 18, 2006, Trustmark completed a private placement of $60.0 million of trust preferred securities through a newly formed Delaware trust affiliate, Trustmark Preferred Capital Trust I (the Trust). The trust preferred securities mature September 30, 2036, are redeemable at Trustmark’s option and bear interest at a variable rate per annum equal to the three-month LIBOR plus 1.72%. Under applicable regulatory guidelines, these trust preferred securities qualify as Tier 1 capital. The proceeds from the sale of the trust preferred securities were used by the Trust to purchase $61.9 million in aggregate principal amount of Trustmark’s junior subordinated debentures. The debentures were issued pursuant to a Junior Subordinated Indenture, dated August 18, 2006, between Trustmark, as issuer, and Wilmington Trust Company, National Association, as trustee. Like the trust preferred securities, the debentures bear interest at a variable rate per annum equal to the three-month LIBOR plus 1.72% and mature on September 30, 2036. The debentures may be redeemed at Trustmark’s option at any time. The interest payments by Trustmark will be used to pay the quarterly distributions payable by the Trust to the holder of the trust preferred securities. However, so long as no event of default has occurred under the debentures, Trustmark may defer interest payments on the debentures (in which case the Trust will also defer distributions otherwise due on the trust preferred securities) for up to 20 consecutive quarters. The debentures are subordinated to the prior payment of any other indebtedness of Trustmark that, by its terms, is not similarly subordinated. The trust preferred securities are recorded as a long-term liability on Trustmark’s balance sheet; however, for regulatory purposes the trust preferred securities are treated as Tier 1 capital under the rules of the Federal Reserve Board (FRB), Trustmark’s primary federal regulatory agency. Trustmark also entered into a Guarantee Agreement, dated August 18, 2006, pursuant to which it has agreed to guarantee the payment by the Trust of distributions on the trust preferred securities and the payment of principal of the trust preferred securities when due, either at maturity or on redemption, but only if and to the extent that the Trust fails to pay distributions on or principal of the trust preferred securities after having received interest payments or principal payments on the junior subordinated debentures from Trustmark for the purpose of paying those distributions or the principal amount of the trust preferred securities. As defined in applicable accounting standards, the Trust, a wholly-owned subsidiary of Trustmark, is considered a variable interest entity for which Trustmark is not the primary beneficiary. Accordingly, the accounts of the Trust are not included in Trustmark’s consolidated financial statements. At December 31, 2020 and 2019, assets for the Trust totaled $61.9 million, resulting from the investment in junior subordinated debentures issued by Trustmark. Liabilities and shareholders’ equity for the Trust also totaled $61.9 million at December 31, 2020 and 2019, 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 2020, net income for the Trust equaled $51 thousand resulting from interest income from the junior subordinated debt securities issued by Trustmark to the Trust, compared with net income of $79 thousand during 2019 and $74 thousand during 2018. Dividends issued to Trustmark by the Trust during 2020 totaled $51 thousand, compared to $79 thousand during 2019 and $74 thousand during 2018.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2020
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, 2020 Year Ended December 31, 2019 (1) Year Ended December 31, 2018 (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 $ 32,213 $ — $ 32,213 $ 42,509 $ — $ 42,509 $ 43,614 $ — $ 43,614 Bank card and other fees 27,398 3,594 30,992 27,973 3,706 31,679 26,904 1,897 28,801 Mortgage banking, net — 125,822 125,822 — 29,822 29,822 — 34,674 34,674 Wealth management 254 — 254 379 — 379 296 — 296 Other, net 7,432 978 8,410 9,528 (161 ) 9,367 6,762 (217 ) 6,545 Total noninterest income $ 67,297 $ 130,394 $ 197,691 $ 80,389 $ 33,367 $ 113,756 $ 77,576 $ 36,354 $ 113,930 Wealth Management Segment Service charges on deposit accounts $ 76 $ — $ 76 $ 94 $ — $ 94 $ 88 $ — $ 88 Bank card and other fees 30 — 30 57 — 57 104 — 104 Wealth management 31,371 — 31,371 30,300 — 30,300 30,042 — 30,042 Other, net 107 50 157 306 103 409 69 117 186 Total noninterest income $ 31,584 $ 50 $ 31,634 $ 30,757 $ 103 $ 30,860 $ 30,303 $ 117 $ 30,420 Insurance Segment Insurance commissions $ 45,176 $ — $ 45,176 $ 42,396 $ — $ 42,396 $ 40,481 $ — $ 40,481 Other, net 92 — 92 33 — 33 5 — 5 Total noninterest income $ 45,268 $ — $ 45,268 $ 42,429 $ — $ 42,429 $ 40,486 $ — $ 40,486 Consolidated Service charges on deposit accounts $ 32,289 $ — $ 32,289 $ 42,603 $ — $ 42,603 $ 43,702 $ — $ 43,702 Bank card and other fees 27,428 3,594 31,022 28,030 3,706 31,736 27,008 1,897 28,905 Mortgage banking, net — 125,822 125,822 — 29,822 29,822 — 34,674 34,674 Insurance commissions 45,176 — 45,176 42,396 — 42,396 40,481 — 40,481 Wealth management 31,625 — 31,625 30,679 — 30,679 30,338 — 30,338 Other, net 7,631 1,028 8,659 9,867 (58 ) 9,809 6,836 (100 ) 6,736 Total noninterest income $ 144,149 $ 130,444 $ 274,593 $ 153,575 $ 33,470 $ 187,045 $ 148,365 $ 36,471 $ 184,836 (1) During the first quarter of 2020, Trustmark revised the composition of its operating segments by moving the Retail Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes. The prior period amounts presented include reclassifications to conform to the current period presentation. (2) 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, 2020
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, 2020 2019 2018 Current Federal $ 40,118 $ 20,068 $ 4,532 State 9,439 7,145 5,997 Deferred Federal (15,840 ) (3,104 ) 9,392 State (3,960 ) (776 ) 2,348 Income tax provision $ 29,757 $ 23,333 $ 22,269 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, 2020 2019 2018 Income tax computed at statutory tax rate $ 39,854 $ 36,497 $ 36,089 Tax exempt interest (4,284 ) (4,951 ) (4,533 ) Nondeductible interest expense 247 564 416 State income taxes, net 7,457 5,645 4,738 Income tax credits, net (9,375 ) (13,473 ) (15,404 ) Death benefit gains (91 ) (123 ) (268 ) Other (4,051 ) (826 ) 1,231 Income tax provision $ 29,757 $ 23,333 $ 22,269 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, 2020 and 2019, which are included in other assets on the accompanying consolidated balance sheets ($ in thousands): December 31, 2020 2019 Deferred tax assets: Loan purchase accounting $ 293 $ 845 Other real estate 2,049 5,845 Accumulated credit losses 39,073 21,774 Deferred compensation 17,465 16,498 Finance and operating lease liabilities 10,024 10,469 Realized built-in losses 10,681 11,431 Securities 2,233 3,028 Pension and other postretirement benefit plans 6,128 5,194 Interest on nonaccrual loans 1,034 942 Loans held for sale 2,754 481 Stock-based compensation 2,749 2,527 Loan fees 3,401 — Other 10,294 8,309 Gross deferred tax asset 108,178 87,343 Deferred tax liabilities: Goodwill and other identifiable intangibles 15,136 15,336 Premises and equipment 11,479 11,913 Finance and operating lease right-of-use assets 9,593 10,127 Mortgage servicing rights 7,108 11,002 Securities 9,712 2,115 Other 4,537 5,192 Gross deferred tax liability 57,565 55,685 Net deferred tax asset $ 50,613 $ 31,658 The following table provides a summary of the changes during the 2020 calendar year in the amount of unrecognized tax benefits that are included in other liabilities in the consolidated balance sheet ($ in thousands): December 31, 2020 2019 2018 Balance at beginning of period $ 1,524 $ 1,249 $ 1,105 Change due to tax positions taken during the current year 353 279 282 Change due to tax positions taken during a prior year 79 134 56 Change due to the lapse of applicable statute of limitations during the current year (175 ) (138 ) (194 ) Change due to settlements with taxing authorities during the current year — — — Balance at end of period $ 1,781 $ 1,524 $ 1,249 Accrued interest, net of federal benefit $ 330 $ 271 $ 212 Unrecognized tax benefits that would impact the effective tax rate, if recognized $ 1,420 $ 1,218 $ 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 2014 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, 2020
Compensation And Retirement Disclosure [Abstract]
Defined Benefit and Other Postretirement Benefits	Note 15 – Defined Benefit and Other Postretirement Benefits Qualified Pension Plan Trustmark maintains a noncontributory tax-qualified defined benefit pension plan titled the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions (the Continuing Plan) to satisfy commitments made by Trustmark to associates covered through plans obtained in acquisitions. The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for the Continuing Plan for the periods presented ($ in thousands): December 31, 2020 2019 Change in benefit obligation: Benefit obligation, beginning of year $ 9,060 $ 9,179 Service cost 254 211 Interest cost 241 361 Actuarial (gain) loss 876 875 Benefits paid (884 ) (1,566 ) Benefit obligation, end of year $ 9,547 $ 9,060 Change in plan assets: Fair value of plan assets, beginning of year $ 3,443 $ 3,954 Actual return on plan assets (87 ) 668 Employer contributions 401 387 Benefit payments (884 ) (1,566 ) Fair value of plan assets, end of year $ 2,873 $ 3,443 Funded status at end of year - net liability $ (6,674 ) $ (5,617 ) Amounts recognized in accumulated other comprehensive loss: Net loss - amount recognized $ 2,564 $ 1,893 Years Ended December 31, 2020 2019 2018 Net periodic benefit cost: Service cost $ 254 $ 211 $ 277 Interest cost 241 361 332 Expected return on plan assets (154 ) (202 ) (227 ) Recognized net loss due to lump sum settlements 119 312 161 Recognized net actuarial loss 326 373 571 Net periodic benefit cost $ 786 $ 1,055 $ 1,114 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) $ 671 $ (277 ) $ (1,017 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ 1,457 $ 778 $ 97 Weighted-average assumptions as of end of year: Discount rate for benefit obligation 1.95 % 2.84 % 3.97 % Discount rate for net periodic benefit cost 2.84 % 3.97 % 3.32 % Expected long-term return on plan assets 5.00 % 5.00 % 5.00 % Plan Assets The weighted-average asset allocations by asset category are presented below for the Continuing Plan at December 31, 2020 and 2019. December 31, 2020 2019 Money market fund 5.0 % 2.0 % Exchange traded funds: Equity securities 43.0 % 46.0 % Fixed income 41.0 % 41.0 % International 11.0 % 11.0 % Total 100.0 % 100.0 % The strategic objective of the investments of the assets in the Continuing Plan aims to provide long-term capital growth with moderate income. The allocation is managed on a total return basis with the average participant age in mind. It is constructed with an intermediate investment time frame with a moderate to high risk tolerance or a long-term investment time frame with a low to moderate risk tolerance. The plan allocation is typically balanced between equity and fixed income. The equity exposure has the potential to earn a return greater than inflation while the fixed income exposure may reduce the risk and volatility of the portfolio to which the equity allocation contributes. Fair Value Measurements At this time, Trustmark presents no fair values that are derived through internal modeling. Should positions requiring fair valuation arise that are not relevant to existing methodologies, Trustmark will make every reasonable effort to obtain market participant assumptions, or independent evaluation. The following table sets forth by level, within the fair value hierarchy, the Continuing Plan’s assets measured at fair value at December 31, 2020 and 2019 ($ in thousands): December 31, 2020 Total Level 1 Level 2 Level 3 Money market fund $ 131 $ 131 $ — $ — Exchange traded funds: Equity securities 1,242 1,242 — — Fixed income 1,182 1,182 — — International 318 318 — — Total assets at fair value $ 2,873 $ 2,873 $ — $ — December 31, 2019 Total Level 1 Level 2 Level 3 Money market fund $ 51 $ 51 $ — $ — Exchange traded funds: Equity securities 1,592 1,592 — — Fixed income 1,417 1,417 — — International 383 383 — — Total assets at fair value $ 3,443 $ 3,443 $ — $ — There have been no changes in the methodologies used in estimating the fair value of plan assets at December 31, 2020. 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, 2020, Trustmark’s minimum required contribution to the Continuing Plan was $306 thousand; however, Trustmark contributed $563 thousand, $257 thousand in excess of the minimum required. For the plan year ending December 31, 2021, Trustmark’s minimum required contribution to the Continuing Plan is expected to be $ 327 thousand . Management and the Board of Directors of Trustmark will monitor the Continuing Plan throughout 20 2 1 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 2021 $ 1,437 2022 997 2023 1,466 2024 1,162 2025 569 2026 - 2030 2,511 Amounts in accumulated other comprehensive loss expected to be recognized as components of net periodic benefit cost during 2021 include a net loss of $594 thousand. Supplemental Retirement Plans Trustmark maintains a nonqualified supplemental retirement plan covering key executive officers and senior officers as well as directors who have elected to defer fees. The plan provides for retirement and/or death benefits based on a participant’s covered salary or deferred fees. Although plan benefits may be paid from Trustmark’s general assets, Trustmark has purchased life insurance contracts on the participants covered under the plan, which may be used to fund future benefit payments under the plan. The measurement date for the plan is December 31. As a result of mergers prior to 2014, Trustmark became the administrator of small nonqualified supplemental retirement plans, for which the plan benefits were frozen prior to the merger date. The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for Trustmark’s nonqualified supplemental retirement plans for the periods presented ($ in thousands): December 31, 2020 2019 Change in benefit obligation: Benefit obligation, beginning of year $ 57,482 $ 53,257 Service cost 77 109 Interest cost 1,576 2,044 Actuarial (gain) loss 4,168 5,498 Benefits paid (3,657 ) (3,426 ) Benefit obligation, end of year $ 59,646 $ 57,482 Change in plan assets: Fair value of plan assets, beginning of year $ — $ — Employer contributions 3,657 3,426 Benefit payments (3,657 ) (3,426 ) Fair value of plan assets, end of year $ — $ — Funded status at end of year - net liability $ (59,646 ) $ (57,482 ) Amounts recognized in accumulated other comprehensive loss: Net loss $ 21,486 $ 18,275 Prior service cost 459 609 Amounts recognized $ 21,945 $ 18,884 Years Ended December 31, 2020 2019 2018 Net periodic benefit cost: Service cost $ 77 $ 109 $ 116 Interest cost 1,576 2,044 1,865 Amortization of prior service cost 150 250 250 Recognized net actuarial loss 957 627 884 Net periodic benefit cost $ 2,760 $ 3,030 $ 3,115 Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes: Net (gain) loss $ 3,211 $ 4,872 $ (4,111 ) Amortization of prior service cost (150 ) (250 ) (250 ) Total recognized in other comprehensive income (loss) $ 3,061 $ 4,622 $ (4,361 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ 5,821 $ 7,652 $ (1,246 ) Weighted-average assumptions as of end of year: Discount rate for benefit obligation 1.95 % 2.84 % 3.97 % Discount rate for net periodic benefit cost 2.84 % 3.97 % 3.32 % 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 2021 $ 3,893 2022 4,168 2023 4,033 2024 4,106 2025 3,774 2026 - 2030 17,296 Amounts in accumulated other comprehensive loss expected to be recognized as components of net periodic benefit cost during 2021 include a loss of $1.2 million and prior service cost of $112 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 $9.2 million in 2020, $8.2 million in 2019 and $7.9 million in 2018.

Stock and Incentive Compensatio

Stock and Incentive Compensation Plans	12 Months Ended
	Dec. 31, 2020
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 and units 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, 2020, the maximum number of shares of Trustmark’s common stock available for issuance under the Stock Plan was 771,055 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. The Monte Carlo simulation was performed by an independent valuation consultant and requires the use of subjective modeling assumptions. These awards are recognized using the straight-line method over the requisite service period. These awards provide for achievement units if performance measures exceed 100%. The restricted share agreement for these awards provides for voting rights and dividend privileges. Beginning in 2020, Trustmark began granting performance units instead of performance awards. The performance units have the same attributes as the previously granted performance awards, except for the performance units do not provide voting rights. The following table summarizes Trustmark’s performance award activity for the periods presented: Years Ended December 31, 2020 2019 2018 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 149,914 $ 32.88 177,695 $ 27.10 213,516 $ 25.37 Granted 53,450 31.98 50,862 33.44 51,174 31.88 Released from restriction (36,357 ) 33.31 (61,347 ) 20.18 (55,351 ) 25.32 Forfeited (21,965 ) 32.97 (17,296 ) 20.18 (31,644 ) 26.26 Nonvested shares, end of year 145,042 $ 32.43 149,914 $ 32.88 177,695 $ 27.10 Time-based Awards Trustmark’s time-based 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-based 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. During 2020, Trustmark began granting time-based units instead of time-based awards. The time-based units have the same attributes as the previously granted time-based awards, except for the time-based units do not provide voting rights. The following table summarizes Trustmark’s time-based award activity for the periods presented: Years Ended December 31, 2020 2019 2018 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 300,006 $ 33.04 321,870 $ 28.48 320,357 $ 25.40 Granted 123,810 31.52 113,673 33.42 118,325 31.96 Released from restriction (110,537 ) 33.58 (124,598 ) 21.64 (107,180 ) 23.02 Forfeited (11,660 ) 32.47 (10,939 ) 32.73 (9,632 ) 29.30 Nonvested shares, end of year 301,619 $ 32.24 300,006 $ 33.04 321,870 $ 28.48 The following table presents information regarding compensation expense for awards under the Stock Plan for the periods presented ($ in thousands): At December 31, 2020 Recognized Compensation Expense Unrecognized Weighted Average for Years Ended December 31, Compensation Life of 2020 2019 2018 Expense Compensation Expense Performance awards $ 815 $ 1,524 $ 861 $ 1,836 1.57 Time-based awards 4,382 3,263 3,009 2,868 1.54 Total $ 5,197 $ 4,787 $ 3,870 $ 4,704

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
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, 2020 and 2019, Trustmark had unused commitments to extend credit of $4.867 billion and $4.349 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, 2020 and 2019, Trustmark’s maximum exposure to credit loss in the event of nonperformance by the other party for letters of credit was $113.8 million and $105.2 million, respectively. These amounts consist primarily of commitments with maturities of less than three years, which have an immaterial carrying value. Trustmark holds collateral to support standby letters of credit when deemed necessary. As of December 31, 2020 and 2019, the fair value of collateral held was $21.9 million and $26.3 million, respectively. Trustmark adopted FASB ASC Topic 326, effective January 1, 2020, which requires Trustmark to estimate expected credit losses for off-balance sheet credit exposures which are not unconditionally cancellable. Trustmark maintains a separate ACL on off-balance sheet credit exposures, including unfunded loan commitments and letters of credit, which is included on the accompanying consolidated balance sheet as of December 31, 2020. Changes in the ACL on off-balance sheet credit exposures were as follows for the period presented ($ in thousands): Year Ended December 31, 2020 Balance at beginning of period $ — FASB ASU 2016-13 adoption adjustment 29,638 Credit loss expense related to off-balance sheet credit exposures 8,934 Balance at end of period $ 38,572 Adjustments to the ACL on off-balance sheet credit exposures are recorded to credit loss expense related to off-balance sheet credit exposures in noninterest expense. The increase in the ACL on off-balance sheet credit exposures for the year ended December 31, 2020 was primarily due to the negative effects of the COVID-19 pandemic. Legal Proceedings Trustmark’s wholly-owned subsidiary, TNB, has been named as a defendant in several lawsuits related to the collapse of the Stanford Financial Group. On August 23, 2009, a purported class action complaint was filed in the District Court of Harris County, Texas, by Peggy Roif Rotstain, Guthrie Abbott, Catherine Burnell, Steven Queyrouze, Jaime Alexis Arroyo Bornstein and Juan C. Olano (collectively, Class Plaintiffs), on behalf of themselves and all others similarly situated, naming TNB and four other financial institutions and one individual, each of which are unaffiliated with Trustmark, as defendants. The complaint seeks to recover (i) alleged fraudulent transfers from each of the defendants in the amount of fees and other monies received by each defendant from entities controlled by R. Allen Stanford (collectively, the Stanford Financial Group) and (ii) damages allegedly attributable to alleged conspiracies by one or more of the defendants with the Stanford Financial Group to commit fraud and/or aid and abet fraud on the asserted grounds that defendants knew or should have known the Stanford Financial Group was conducting an illegal and fraudulent scheme. Class Plaintiffs have demanded a jury trial. Class Plaintiffs did not quantify damages. In November 2009, the lawsuit was removed to federal court by certain defendants and then transferred by the United States Panel on Multidistrict Litigation to federal court in the Northern District of Texas (Dallas) where multiple Stanford related matters are being consolidated for pre-trial proceedings. In May 2010, all defendants (including TNB) filed motions to dismiss the lawsuit. In August 2010, the court authorized and approved the formation of an Official Stanford Investors Committee (OSIC) to represent the interests of Stanford investors and, under certain circumstances, to file legal actions for the benefit of Stanford investors. In December 2011, the OSIC filed a motion to intervene in this action. In September 2012, the district court referred the case to a magistrate judge for hearing and determination of certain pretrial issues. In December 2012, the court granted the OSIC’s motion to intervene, and the OSIC filed an Intervenor Complaint against one of the other defendant financial institutions. In February 2013, the OSIC filed a second Intervenor Complaint that asserts claims against TNB and the remaining defendant financial institutions. The OSIC seeks to recover: ( i ) alleged fraudulent transfers in the amount of the fees each of the defendants allegedly received from Stanford Financial Group, the profits each of the defendants allegedly made from Stanford Financial Group deposits, and other monies each of the defendants allegedly received from Stanford Financial Group; (ii) damages attributable to alleged conspiracies by each of the defendants with the Stanford Financial Group to commit fraud and/or aid and abet fraud and conversion on the asserted grounds that the defendants knew or should have known the Stanford Financial Group was conducting an illegal and fraudulent scheme; and (iii) punitive damages. The OSIC did not quantify damages. In July 2013, all defendants (including TNB) filed motions to dismiss the OSIC’s claims. In March 2015, the court entered an order authorizing the parties to conduct discovery regarding class certification, staying all other discovery and setting a deadline for the parties to complete briefing on class certification issues. In April 2015, the court granted in part and denied in part the defendants’ motions to dismiss the Class Plaintiffs’ claims and the OSIC’s claims. The court dismissed all of the Class Plaintiffs’ fraudulent transfer claims and dismissed certain of the OSIC’s claims. The court denied the motions by TNB and the other financial institution defendants to dismiss the OSIC’s constructive fraudulent transfer claims. On June 23, 2015, the court allowed the Class Plaintiffs to file a Second Amended Class Action Complaint (SAC), which asserted new claims against TNB and certain of the other defendants for (i) aiding, abetting and participating in a fraudulent scheme, (ii) aiding, abetting and participating in violations of the Texas Securities Act, (iii) aiding, abetting and participating in breaches of fiduciary duty, (iv) aiding, abetting and participating in conversion and (v) conspiracy. On July 14, 2015, the defendants (including TNB) filed motions to dismiss the SAC and to reconsider the court’s prior denial to dismiss the OSIC’s constructive fraudulent transfer claims against TNB and the other financial institutions that are defendants in the action. On July 27, 2016, the court denied the motion by TNB and the other financial institution defendants to dismiss the SAC and also denied the motion by TNB and the other financial institution defendants to reconsider the court’s prior denial to dismiss the OSIC’s constructive fraudulent transfer claims. On August 24, 2016, TNB filed its answer to the SAC. On October 20, 2017, the OSIC filed a motion seeking an order lifting the discovery stay and establishing a trial schedule. On November 4, 2016, the OSIC filed a First Amended Intervenor Complaint, which added claims for (i) aiding, abetting or participation in violations of the Texas Securities Act and (ii) aiding, abetting or participation in the breach of fiduciary duty. On November 7, 2017, the court denied the Class Plaintiffs’ motion seeking class certification and designation of class representatives and counsel, finding that common issues of fact did not predominate. The court granted the OSIC’s motion to lift the discovery stay that it had previously ordered. On May 3, 2019, individual investors and entities filed motions to intervene in the action. On September 18, 2019, the court denied the motions to intervene. On October 14, 2019, certain of the proposed intervenors filed a notice of appeal. On December 14, 2009, a different Stanford-related lawsuit was filed in the District Court of Ascension Parish, Louisiana, individually by Harold Jackson, Paul Blaine and Carolyn Bass Smith, Christine Nichols, and Ronald and Ramona Hebert naming TNB (misnamed as Trust National Bank) and other individuals and entities not affiliated with Trustmark as defendants. The complaint seeks to recover the money lost by these individual plaintiffs as a result of the collapse of the Stanford Financial Group (in addition to other damages) under various theories and causes of action, including negligence, breach of contract, breach of fiduciary duty, negligent misrepresentation, detrimental reliance, conspiracy, and violation of Louisiana’s uniform fiduciary, securities, and racketeering laws. The complaint does not quantify the amount of money the plaintiffs seek to recover. In January 2010, the lawsuit was removed to federal court by certain defendants and then transferred by the United States Panel on Multidistrict Litigation to federal court in the Northern District of Texas (Dallas) where multiple Stanford related matters are being consolidated for pre-trial proceedings. On March 29, 2010, the court stayed the case. TNB filed a motion to lift the stay, which was denied on February 28, 2012. In September 2012, the district court referred the case to a magistrate judge for hearing and determination of certain pretrial issues. On April 11, 2016, Trustmark learned that a different Stanford-related lawsuit had been filed on that date in the Superior Court of Justice in Ontario, Canada, by The Toronto-Dominion Bank (“TD Bank”), naming TNB and three other financial institutions not affiliated with Trustmark as defendants. The complaint seeks a declaration specifying the degree to which each of TNB and the other defendants are liable in respect of any loss and damage for which TD Bank is found to be liable in a litigation commenced against TD Bank brought by the Joint Liquidators of Stanford International Bank Limited in the Superior Court of Justice, Commercial List in Ontario, Canada (the “Joint Liquidators’ Action”), as well as contribution and indemnity in respect of any judgment, interest and costs TD Bank is ordered to pay in the Joint Liquidators’ Action. To date, TNB has not been served in connection with this action. On November 1, 2019, TNB was named as a defendant in a complaint filed by Paul Blaine Smith, Carolyn Bass Smith and other plaintiffs identified therein (the Smith Complaint). The Smith Complaint was filed in District Court, Harris County, Texas and named TNB and four other financial institutions and one individual, each of which are unaffiliated with Trustmark, as defendants. The Smith Complaint relates to the collapse of the Stanford Financial Group, as does the other pending litigation relating to Stanford summarized above. Plaintiffs in the Smith Complaint have demanded a jury trial. On January 15, 2020, the court granted Stanford Financial Group receiver’s motion to stay the state court action. On February 26, 2020, the lawsuit was removed to federal court in the Southern District of Texas by TNB. Trustmark and its counsel are carefully evaluating the Smith Complaint in the form that is publicly available, and will update the foregoing description to the extent that additional material facts are ascertained. TNB’s relationship with the Stanford Financial Group began as a result of Trustmark’s acquisition of a Houston-based bank in August 2006, and consisted of correspondent banking and other traditional banking services in the ordinary course of business. All Stanford-related lawsuits are in pre-trial stages. On December 30, 2019, a complaint was filed in the United States District Court for the Southern District of Mississippi, Northern Division (the Court) by Alysson Mills in her capacity as Court-appointed Receiver (the Receiver) for Arthur Lamar Adams (Adams) and Madison Timber Properties, LLC (Madison Timber), naming TNB, two other Mississippi-based financial institutions both of which are unaffiliated with Trustmark and two individuals, one of who was employed by TNB at all times relevant to the complaint and the other was employed either by TNB or one of the other defendant financial institutions, as defendants. The complaint seeks to recover from the defendants, for the benefit of the receivership estate and also for certain investors who were allegedly defrauded by Adams and Madison Timber, damages (including punitive damages) and related costs allegedly attributable to actions of the defendants that allegedly enabled illegal and fraudulent activities engaged in by Adams and Madison Timber. The Receiver did not quantify damages. TNB’s relationship with Adams and Madison Timber consisted of traditional banking services in the ordinary course of business. Trustmark and its subsidiaries are also parties to other lawsuits and other claims that arise in the ordinary course of business. Some of the lawsuits assert claims related to the lending, collection, servicing, investment, trust and other business activities, and some of the lawsuits allege substantial claims for damages. All pending legal proceedings described above are being vigorously contested. In accordance FASB ASC Subtopic 450-20, “Loss Contingencies,” Trustmark will establish an accrued liability for litigation matters when those matters present loss contingencies that are both probable and reasonably estimable. At the present time, Trustmark believes, based on its evaluation and the advice of legal counsel, that a loss in any such proceeding is not probable and a reasonable estimate cannot reasonably be made.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2020
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 2.500% at both December 31, 2020 and 2019. Accumulated other comprehensive loss, net of tax, is not included in computing regulatory capital. Trustmark has elected the five-year phase-in transition period related to adopting FASB ASU 2016-13 for regulatory capital purposes. 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, 2020, 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, 2020. 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, 2020, which Management believes have affected Trustmark’s or TNB’s present classification. The following table provides Trustmark’s and TNB’s actual regulatory capital amounts and ratios under regulatory capital standards in effect at December 31, 2020 and 2019 ($ in thousands): Actual Regulatory Capital Minimum To Be Well Amount Ratio Requirement Capitalized At December 31, 2020: Common Equity Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,395,844 11.62 % 7.000 % n/a Trustmark National Bank 1,412,015 11.75 % 7.000 % 6.50 % Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,455,844 12.11 % 8.500 % n/a Trustmark National Bank 1,412,015 11.75 % 8.500 % 8.00 % Total Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,696,794 14.12 % 10.500 % n/a Trustmark National Bank 1,530,044 12.73 % 10.500 % 10.00 % Tier 1 Leverage (to Average Assets) Trustmark Corporation $ 1,455,844 9.33 % 4.00 % n/a Trustmark National Bank 1,412,015 9.07 % 4.00 % 5.00 % At December 31, 2019: Common Equity Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,312,668 11.93 % 7.000 % n/a Trustmark National Bank 1,352,893 12.30 % 7.000 % 6.50 % Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,372,668 12.48 % 8.500 % n/a Trustmark National Bank 1,352,893 12.30 % 8.500 % 8.00 % Total Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,457,760 13.25 % 10.500 % n/a Trustmark National Bank 1,437,985 13.07 % 10.500 % 10.00 % Tier 1 Leverage (to Average Assets) Trustmark Corporation $ 1,372,668 10.48 % 4.00 % n/a Trustmark National Bank 1,352,893 10.35 % 4.00 % 5.00 % 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 2021, TNB will have available approximately $86.7 million plus its net income for that year to pay as dividends. Stock Repurchase Program On March 11, 2016, the Board of Directors of Trustmark authorized a stock repurchase program under which $100.0 million of Trustmark’s outstanding common stock could be acquired through March 31, 2019. Trustmark repurchased approximately 1.2 million shares of its common stock valued at $36.9 million during the year ended December 31, 2019, compared to 2.0 million shares of its common stock valued at $62.4 million repurchased during the year ended December 31, 2018 and no common stock repurchased during the year ended December 31, 2017. Under the 2016 program, Trustmark repurchased approximately 3.2 million shares valued at $100.0 million. The Board of Directors of Trustmark authorized a stock repurchase program effective April 1, 2019 under which $100.0 million of Trustmark’s outstanding common stock could be acquired through March 31, 2020. The adoption of this stock repurchase program followed the receipt of non-objection from the FRB. Trustmark repurchased approximately 887 thousand shares of its common stock valued at $27.5 million during the year ended December 31, 2020, compared to approximately 601 thousand shares of its common stock valued at $19.7 million during the year ended December 31, 2019. Under the 2019 program, Trustmark repurchased approximately 1.5 million shares of its common stock valued at $47.2 million. On January 28, 2020, the Board of Directors of Trustmark authorized a new stock repurchase program effective April 1, 2020 under which $100.0 million of Trustmark’s outstanding common stock may be acquired through December 31, 2021. On March 9, 2020, Trustmark suspended its share repurchase programs to preserve capital to support customers during the COVID-19 pandemic. Trustmark resumed the repurchase of its shares in January 2021. Under this authority, Trustmark repurchased approximately 16 thousand shares of its outstanding common stock valued at $446 thousand during January 2021. The shares may be purchased from time to time at prevailing market prices, through open market or privately negotiated transactions, depending on market conditions. There is no guarantee as to the number of shares that will be repurchased by Trustmark, and Trustmark may discontinue repurchases at any time at Management’s discretion. Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss The following tables present the net change in the components of accumulated other comprehensive loss and the related tax effects allocated to each component for the years ended December 31, 2020, 2019 and 2018 ($ in thousands). The amortization of prior service cost, recognized net loss due to lump sum settlements and change in net actuarial loss 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 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, 2020 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ 30,622 $ (7,657 ) $ 22,965 Change in net unrealized holding loss on securities transferred to held to maturity 3,177 (794 ) 2,383 Total securities available for sale and transferred securities 33,799 (8,451 ) 25,348 Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans (5,128 ) 1,282 (3,846 ) Reclassification adjustments for changes realized in net income: Net change in prior service costs 150 (38 ) 112 Recognized net loss due to lump sum settlements 119 (30 ) 89 Change in net actuarial loss 1,128 (282 ) 846 Total pension and other postretirement benefit plans (3,731 ) 932 (2,799 ) Total other comprehensive income (loss) $ 30,068 $ (7,519 ) $ 22,549 Year Ended December 31, 2019 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ 44,136 $ (11,033 ) $ 33,103 Change in net unrealized holding loss on securities transferred to held to maturity 3,605 (901 ) 2,704 Total securities available for sale and transferred securities 47,741 (11,934 ) 35,807 Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans (5,703 ) 1,425 (4,278 ) Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (63 ) 187 Recognized net loss due to lump sum settlements 312 (77 ) 235 Change in net actuarial loss 796 (199 ) 597 Total pension and other postretirement benefit plans (4,345 ) 1,086 (3,259 ) Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives (145 ) 36 (109 ) Reclassification adjustment for (gain) loss realized in net income (479 ) 119 (360 ) Total cash flow hedge derivatives (624 ) 155 (469 ) Total other comprehensive income (loss) $ 42,772 $ (10,693 ) $ 32,079 Year Ended December 31, 2018 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ (19,221 ) $ 4,805 $ (14,416 ) Change in net unrealized holding loss on securities transferred to held to maturity 3,761 (940 ) 2,821 Total securities available for sale and transferred securities (15,460 ) 3,865 (11,595 ) Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans 3,742 (936 ) 2,806 Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (63 ) 187 Recognized net loss due to lump sum settlements 161 (39 ) 122 Change in net actuarial loss 1,225 (306 ) 919 Total pension and other postretirement benefit plans 5,378 (1,344 ) 4,034 Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives 497 (124 ) 373 Reclassification adjustment for (gain) loss realized in net income (322 ) 80 (242 ) Total cash flow hedge derivatives 175 (44 ) 131 Total other comprehensive income (loss) $ (9,907 ) $ 2,477 $ (7,430 ) 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, 2018 $ (26,535 ) $ (13,468 ) $ 278 $ (39,725 ) Other comprehensive income (loss) before reclassification (11,595 ) 2,806 373 (8,416 ) Amounts reclassified from accumulated other comprehensive loss — 1,228 (242 ) 986 Net other comprehensive income (loss) (11,595 ) 4,034 131 (7,430 ) Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act (5,694 ) (2,890 ) 60 (8,524 ) Balance, December 31, 2018 (43,824 ) (12,324 ) 469 (55,679 ) Other comprehensive income (loss) before reclassification 35,807 (4,278 ) (109 ) 31,420 Amounts reclassified from accumulated other comprehensive loss — 1,019 (360 ) 659 Net other comprehensive income (loss) 35,807 (3,259 ) (469 ) 32,079 Balance, December 31, 2019 (8,017 ) (15,583 ) — (23,600 ) Other comprehensive income (loss) before reclassification 25,348 (3,846 ) — 21,502 Amounts reclassified from accumulated other comprehensive loss — 1,047 — 1,047 Net other comprehensive income (loss) 25,348 (2,799 ) — 22,549 Balance, December 31, 2020 $ 17,331 $ (18,382 ) $ — $ (1,051 )

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2020
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, 2020 and 2019, 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, 2020 and 2019. December 31, 2020 Total Level 1 Level 2 Level 3 U.S. Government agency obligations $ 18,041 $ — $ 18,041 $ — Obligations of states and political subdivisions 5,835 — 5,835 — Mortgage-backed securities 1,967,939 — 1,967,939 — Securities available for sale 1,991,815 — 1,991,815 — Loans held for sale 446,951 — 446,951 — Mortgage servicing rights 66,464 — — 66,464 Other assets - derivatives 47,768 145 38,063 9,560 Other liabilities - derivatives 5,324 666 4,658 — December 31, 2019 Total Level 1 Level 2 Level 3 U.S. Government agency obligations $ 22,327 $ — $ 22,327 $ — Obligations of states and political subdivisions 25,465 — 25,465 — Mortgage-backed securities 1,554,612 — 1,554,612 — Securities available for sale 1,602,404 — 1,602,404 — Loans held for sale 226,347 — 226,347 — Mortgage servicing rights 79,394 — — 79,394 Other assets - derivatives 17,956 244 16,273 1,439 Other liabilities - derivatives 6,063 4,414 1,649 — The changes in Level 3 assets measured at fair value on a recurring basis for the years ended December 31, 2020 and 2019 are summarized as follows ($ in thousands): MSR Other Assets - Derivatives Balance, January 1, 2020 $ 79,394 $ 1,439 Total net (loss) gain included in Mortgage banking, net (1) (42,735 ) 40,669 Additions 29,805 — Sales — (32,548 ) Balance, December 31, 2020 $ 66,464 $ 9,560 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, 2020 $ (26,146 ) $ 25,031 Balance, January 1, 2019 $ 95,596 $ 1,187 Total net (loss) gain included in Mortgage banking, net (1) (32,913 ) 6,775 Additions 16,711 — Sales — (6,523 ) Balance, December 31, 2019 $ 79,394 $ 1,439 The amount of total gains (losses) for the period included in earnings that are attributable to the change in unrealized gains or losses still held at December 31, 2019 $ (21,078 ) $ 1,284 (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, 2020, which have been measured at fair value on a nonrecurring basis, include collateral-dependent LHFI. A loan is collateral dependent when the borrower is experiencing financial difficulty and repayment of the loan is expected to be provided substantially through the sale of the collateral. The expected credit loss for collateral-dependent loans is measured as the difference between the amortized cost basis of the loan and the fair value of the collateral, adjusted for the estimated cost to sell. 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. At December 31, 2020, Trustmark had outstanding balances of $43.4 million with a related ACL of $4.4 million in collateral-dependent LHFI. At December 31, 2019, Trustmark had $41.2 million with a related allowance of $5.5 million in impaired LHFI that were individually evaluated for impairment and written down to fair value of the underlying collateral less cost to sell based on the fair value of the collateral or other unobservable input. Both the collateral-dependent LHFI and the individually evaluated impaired LHFI are classified as Level 3 in the fair value hierarchy. 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 recorded at the fair value less cost to sell (estimated fair value) at the time of foreclosure. 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 $10.1 million were re-measured during 2020, requiring write-downs of $2.0 million to reach their current fair values compared to $15.0 million of foreclosed assets that were re-measured during 2019, requiring write-downs of $2.4 million. Fair Value of Financial Instruments FASB ASC Topic 825 requires disclosure of the fair value of financial assets and financial liabilities, including those financial assets and financial liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis. The carrying amounts and estimated fair values of financial instruments at December 31, 2020 and 2019 were as follows ($ in thousands): December 31, 2020 December 31, 2019 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Financial Assets: Level 2 Inputs: Cash and short-term investments $ 1,952,554 $ 1,952,554 $ 358,916 $ 358,916 Securities held to maturity 538,072 563,115 738,099 746,202 Level 3 Inputs: Net LHFI and PPP loans 10,317,352 10,312,395 9,251,351 9,235,674 Net acquired loans (1) — — 71,786 71,786 Financial Liabilities: Level 2 Inputs: Deposits 14,048,764 14,052,863 11,245,557 11,250,071 Federal funds purchased and securities sold under repurchase agreements 164,519 164,519 256,020 256,020 Other borrowings 168,252 168,252 85,396 85,374 Subordinated notes 122,921 127,500 — — Junior subordinated debt securities 61,856 46,083 61,856 50,722 (1) Upon adoption of FASB ASC Topic 326 at January 1, 2020, Trustmark elected to account for its existing acquired loans as purchased credit deteriorated loans included within the LHFI portfolio. See Note 5 – Acquired Loans for additional details. 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, 2020, 2019 and 2018, a net gain of $10.5 million, $1.5 million and $1.4 million, respectively, was recorded as noninterest income in mortgage banking, net for changes in the fair value of the LHFS accounted for under the fair value option. Interest and fees on LHFS and LHFI for the years ended December 31, 2020 included $6.9 million of interest earned on the LHFS accounted for under the fair value option compared to $5.9 million and $4.9 million for the years ended December 31, 2019 and 2018, respectively. 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 $141.2 million and $57.1 million at December 31, 2020 and 2019, respectively, and are included in LHFS on the accompanying consolidated balance sheets. The following table provides information about the fair value and the contractual principal outstanding of the LHFS accounted for under the fair value option as of December 31, 2020 and 2019 ($ in thousands): December 31, 2020 2019 Fair value of LHFS $ 305,791 $ 169,285 LHFS contractual principal outstanding 290,625 164,420 Fair value less unpaid principal $ 15,166 $ 4,865

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2020
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 the Trust throughout the five-year 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, 2020, 2019 and 2018. The interest rate swap matured on December 31, 2019; therefore, there was no accumulated net after-tax amount related to the effective cash flow hedge included in accumulated other comprehensive income (loss) at December 31, 2020 and 2019. Amounts reported in accumulated other comprehensive income (loss) related to this derivative were reclassified to other interest expense as interest payments were made on Trustmark’s variable rate junior subordinated debentures. Derivatives not Designated as Hedging Instruments Trustmark utilizes a portfolio of exchange-traded derivative instruments, such as Treasury note futures contracts and option contracts, to achieve a fair value return that economically hedges changes in the fair value of the MSR attributable to interest rates. These transactions are considered freestanding derivatives that do not otherwise qualify for hedge accounting. The total notional amount of these derivative instruments was $326.5 million at December 31, 2020 compared to $564.0 million at December 31, 2019. 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 $7.8 million for the year ended December 31, 2020, compared to a net negative ineffectiveness of $11.5 million for the year ended December 31, 2019 and a net positive ineffectiveness of $2.4 million for the year ended December 31, 2018. 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 $377.5 million at December 31, 2020, with a negative valuation adjustment of $3.1 million, compared to $209.0 million at December 31, 2019, with a negative valuation adjustment of $486 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 $329.3 million at December 31, 2020, with a positive valuation adjustment of $9.6 million, compared to $92.1 million at December 31, 2019, with a positive valuation adjustment of $1.4 million. Trustmark offers certain derivatives products directly to qualified commercial lending clients seeking to manage their interest rate risk. Trustmark economically hedges interest rate swap transactions executed with commercial lending clients by entering into offsetting interest rate swap transactions with institutional derivatives market participants. Derivatives transactions executed as part of this program are not designated as qualifying hedging relationships and are, therefore, carried at fair value with the change in fair value recorded as noninterest income in bank card and other fees. Because these derivatives have mirror-image contractual terms, in addition to collateral provisions which mitigate the impact of non-performance risk, the changes in fair value are expected to substantially offset. The Chicago Mercantile Exchange rules legally characterize variation margin collateral payments made or received for centrally cleared interest rate swaps as settlements rather than collateral. As a result, centrally cleared interest rate swaps included in other assets and other liabilities are presented on a net basis in the accompanying consolidated balance sheets. As of December 31, 2020, Trustmark had interest rate swaps with an aggregate notional amount of $1.125 billion related to this program, compared to $893.1 million as of December 31, 2019. 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, 2020 and 2019, the termination value of interest rate swaps in a liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, related to these agreements was $1.3 million and $1.0 million, respectively. As of December 31, 2020, Trustmark had posted collateral of $1.6 million against its obligations because of negotiated thresholds and minimum transfer amounts under these agreements. If Trustmark had breached any of these triggering provisions at December 31, 2020, it could have been required to settle its obligations under the agreements at the termination value. Credit risk participation agreements arise when Trustmark contracts with other financial institutions, as a guarantor or beneficiary, to share credit risk associated with certain interest rate swaps. These agreements provide for reimbursement of losses resulting from a third-party default on the underlying swap. At both December 31, 2020 and 2019, Trustmark had entered into three risk participation agreements as a beneficiary with aggregate notional amounts of $41.1 million and $37.6 million, respectively. At December 31, 2020, Trustmark had entered into twenty-four risk participation agreements as a guarantor with an aggregate notional amount of $172.0 million compared to ten risk participation agreements as a guarantor with an aggregate notional amount of $79.3 million at December 31, 2019. The aggregate fair values of these risk participation agreements were immaterial at December 31, 2020 and 2019. Tabular Disclosures The following tables disclose the fair value of derivative instruments in Trustmark’s consolidated balance sheets as of December 31, 2020 and 2019 as well as the effect of these derivative instruments on Trustmark’s results of operations for the periods presented ($ in thousands): December 31, 2020 2019 Derivatives not designated as hedging instruments Interest rate contracts: Exchange traded purchased options included in other assets $ 145 $ 244 OTC written options (rate locks) included in other assets 9,560 1,439 Interest rate swaps included in other assets (1) 37,974 16,209 Credit risk participation agreements included in other assets 89 64 Futures contracts included in other liabilities 34 2,654 Forward contracts included in other liabilities 3,145 486 Exchange traded written options included in other liabilities 632 1,760 Interest rate swaps included in other liabilities (1) 1,313 1,122 Credit risk participation agreements included in other liabilities 200 41 (1) In accordance with GAAP, the variation margin collateral payments made or received for interest rate swaps that are centrally cleared are legally characterized as settled. As a result, the centrally cleared interest rate swaps included in other assets and other liabilities are presented on a net basis in the accompanying consolidated balance sheets. Years Ended December 31, 2020 2019 2018 Derivatives in hedging relationships Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) and recognized in other interest expense $ — $ 479 $ 322 Derivatives not designated as hedging instruments Amount of gain (loss) recognized in mortgage banking, net $ 39,436 $ 11,096 $ (6,191 ) Amount of gain (loss) recognized in bank card and other fees (1,022 ) (776 ) (357 ) 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, 2020 2019 2018 Derivatives in cash flow hedging relationship Amount of gain (loss) recognized in other comprehensive income (loss), net of tax $ — $ (109 ) $ 373 Information about financial instruments that are eligible for offset in the consolidated balance sheets as of December 31, 2020 and 2019 is presented in the following tables ($ in thousands): Offsetting of Derivative Assets As of December 31, 2020 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 $ 37,974 $ — $ 37,974 $ — $ — $ 37,974 Offsetting of Derivative Liabilities As of December 31, 2020 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 $ 1,313 $ — $ 1,313 $ — $ (1,313 ) $ — Offsetting of Derivative Assets As of December 31, 2019 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 $ 16,209 $ — $ 16,209 $ — $ — $ 16,209 Offsetting of Derivative Liabilities As of December 31, 2019 Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Statement of Financial Position Net Amounts of Liabilities presented in the Statement of Financial Position Financial Instruments Cash Collateral Posted Net Amount Derivatives $ 1,122 $ — $ 1,122 $ — $ (1,390 ) $ (268 )

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2020
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 FBBI, Trustmark’s Insurance Segment provides a full range of retail insurance products including commercial risk management products, bonding, group benefits and personal lines coverage. During the first quarter of 2020, Trustmark revised the composition of its operating segments by moving the Retail Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes. The prior periods presented include reclassifications to conform to the current period presentation. The accounting policies of each reportable segment are the same as those of Trustmark except for its internal allocations. Noninterest expenses for back-office operations support are allocated to segments based on estimated uses of those services. Trustmark measures the net interest income of its business segments with a process that assigns cost of funds or earnings credit on a matched-term basis. This process, called “funds transfer pricing”, charges an appropriate cost of funds to assets held by a business unit, or credits the business unit for potential earnings for carrying liabilities. The net of these charges and credits flows through to the General Banking Segment, which contains the management team responsible for determining TNB’s funding and interest rate risk strategies. The following table discloses financial information by reportable segment for the periods presented ($ in thousands): Years Ended December 31, 2020 2019 2018 General Banking Net interest income $ 420,225 $ 419,597 $ 412,455 Provision for loan losses, net 36,124 10,622 17,098 Noninterest income 197,691 113,756 113,930 Noninterest expense 410,744 367,976 353,174 Income before income taxes 171,048 154,755 156,113 Income taxes 25,109 18,638 18,313 General banking net income $ 145,939 $ 136,117 $ 137,800 Selected Financial Information Total assets $ 16,226,358 $ 13,140,467 $ 12,896,799 Depreciation and amortization $ 40,351 $ 38,634 $ 38,181 Wealth Management Net interest income $ 6,082 $ 6,750 $ 6,739 Provision for loan losses, net (11 ) 217 (110 ) Noninterest income 31,634 30,860 30,420 Noninterest expense 30,318 28,882 31,385 Income before income taxes 7,409 8,511 5,884 Income taxes 1,853 2,123 1,472 Wealth Management net income $ 5,556 $ 6,388 $ 4,412 Selected Financial Information Total assets $ 242,429 $ 283,164 $ 320,742 Depreciation and amortization $ 274 $ 270 $ 187 Insurance Net interest income $ 230 $ 242 $ 226 Noninterest income 45,268 42,429 40,486 Noninterest expense 34,173 32,144 30,856 Income before income taxes 11,325 10,527 9,856 Income taxes 2,795 2,572 2,484 Insurance net income $ 8,530 $ 7,955 $ 7,372 Selected Financial Information Total assets $ 83,053 $ 74,246 $ 68,919 Depreciation and amortization $ 700 $ 516 $ 572 Consolidated Net interest income $ 426,537 $ 426,589 $ 419,420 Provision for loan losses, net 36,113 10,839 16,988 Noninterest income 274,593 187,045 184,836 Noninterest expense 475,235 429,002 415,415 Income before income taxes 189,782 173,793 171,853 Income taxes 29,757 23,333 22,269 Consolidated net income $ 160,025 $ 150,460 $ 149,584 Selected Financial Information Total assets $ 16,551,840 $ 13,497,877 $ 13,286,460 Depreciation and amortization $ 41,325 $ 39,420 $ 38,940

Parent Company Only Financial I

Parent Company Only Financial Information	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 Assets: Investment in banks $ 1,769,165 $ 1,707,644 Other assets 158,360 15,778 Total Assets $ 1,927,525 $ 1,723,422 Liabilities and Shareholders' Equity: Accrued expense $ 1,631 $ 864 Subordinated notes 122,921 — Junior subordinated debt securities 61,856 61,856 Shareholders' equity 1,741,117 1,660,702 Total Liabilities and Shareholders' Equity $ 1,927,525 $ 1,723,422 Condensed Statements of Income Years Ended December 31, 2020 2019 2018 Revenue: Dividends received from banks $ 109,243 $ 120,297 $ 128,592 Earnings of subsidiaries over distributions 53,724 32,971 23,791 Other income 66 90 86 Total Revenue 163,033 153,358 152,469 Expense: Other expense 3,008 2,898 2,885 Total Expense 3,008 2,898 2,885 Net Income $ 160,025 $ 150,460 $ 149,584 Condensed Statements of Cash Flows Years Ended December 31, 2020 2019 2018 Operating Activities: Net income $ 160,025 $ 150,460 $ 149,584 Adjustments to reconcile net income to net cash provided by operating activities: Net change in investment in subsidiaries (53,724 ) (32,971 ) (23,791 ) Other (326 ) (1,800 ) (1,395 ) Net cash from operating activities 105,975 115,689 124,398 Financing Activities: Proceeds from subordinated notes 122,900 — — Common stock dividends (58,769 ) (59,804 ) (62,425 ) Repurchase and retirement of common stock (27,538 ) (56,615 ) (62,421 ) Net cash from financing activities 36,593 (116,419 ) (124,846 ) Net change in cash and cash equivalents 142,568 (730 ) (448 ) Cash and cash equivalents at beginning of year 15,707 16,437 16,885 Cash and cash equivalents at end of year $ 158,275 $ 15,707 $ 16,437 Trustmark (parent company only) paid income taxes of approximately $46.6 million in 2020, $24.8 million in 2019 and $12.4 million in 2018. Trustmark did not pay or receive interest during 2020, compared to interest received of $482 thousand and $320 thousand during 2019 and 2018, respectively.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
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 183 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 2021 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. Financial Accounting Standards Board (FASB) Accounting Standard Update (ASU) 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” was adopted by Trustmark on January 1, 2020. ASU 2016-13 introduced FASB ASC Topic 326, which requires a current expected credit losses methodology for estimating allowances for credit losses and applies to all financial instruments carried at amortized cost, including securities held to maturity, and makes targeted improvements to the accounting for credit losses on securities available for sale. Under FASB ASC Topic 326, the allowance for credit losses is an estimate measured using relevant information about past events, including historical credit loss experience on financial assets with similar risk characteristics, current conditions, and reasonable and supportable forecasts that affect the collectability of the remaining cash flows over the contractual term of the financial assets. Trustmark has adopted a zero-credit loss assumption for certain classes of securities. This zero-credit loss assumption applies to debt issuances of the U.S. Treasury and agencies and instrumentalities of the United States government. The reasons behind the adoption of the zero-credit loss assumption were as follows: • High credit rating • Long history with no credit losses • Guaranteed by a sovereign entity • Widely recognized as “risk-free rate” • Can print its own currency • Currency is routinely held by central banks, used in international commerce, and commonly viewed as reserve currency • Currently under the U.S. Government conservatorship or receivership Trustmark continuously monitors any changes in economic conditions, credit downgrades, changes to explicit or implicit guarantees granted to certain debt issuers, and any other relevant information that would indicate potential credit deterioration and prompt Trustmark to reconsider its zero-credit loss assumption. Securities Available for Sale FASB ASC Subtopic 326-30, “Financial Instruments-Credit Losses-Available-for-Sale Debt Securities,” replaced the concept of other-than-temporarily impaired with the allowance for credit losses. Unlike securities held to maturity, securities available for sale are evaluated on an individual level and pooling of securities is not allowed. Quarterly, Trustmark evaluates if any security has a fair value less than its amortized cost. Once these securities are identified, in order to determine whether a decline in fair value resulted from a credit loss or other factors, Trustmark performs further analysis as outlined below: • Review the extent to which the fair value is less than the amortized cost and observe the security’s lowest credit rating as reported by third-party credit ratings companies. • The securities that violate the credit loss triggers above would be subjected to additional analysis that may include, but is not limited to: changes in market interest rates, changes in securities credit ratings, security type, service area economic factors, financial performance of the issuer/or obligor of the underlying issue and third-party guarantee. • If Trustmark determines that a credit loss exists, the credit portion of the allowance will be measured using a discounted cash flow (DCF) analysis using the effective interest rate as of the security’s purchase date. The amount of credit loss Trustmark records will be limited to the amount by which the amortized cost exceeds the fair value. The DCF analysis utilizes contractual maturities, as well as third-party credit ratings and cumulative default rates published annually by Moody’s Investor Service (Moody’s). Accrued interest receivable is excluded from the estimate of credit losses for securities available for sale. Securities Held to Maturity FASB ASC Subtopic 326-20, “Financial Instruments-Credit Losses-Measured at Amortized Cost,” requires institutions to measure expected credit losses on financial assets carried at amortized cost on a collective or pool basis when similar risks exist. Trustmark uses several levels of segmentation in order to measure expected credit losses for its held to maturity securities: • The portfolio is segmented into agency and non-agency securities. • The non-agency securities are separated into municipal, mortgage, and corporate securities. Each individual segment is categorized by third-party credit ratings. As discussed above, Trustmark has determined that for certain classes of securities it would be appropriate to assume the expected credit loss to be zero, which include debt issuances of the U.S. Treasury and agencies and instrumentalities of the United States government. This assumption is reviewed and attested to quarterly. Trustmark uses an internally built model to verify the accuracy of third-party provided calculations. Accrued interest receivable is excluded from the estimate of credit losses for securities held to maturity.
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 FASB ASC Topic 825, “Financial Instruments,” with interest income on the LHFS reported in interest and fees on LHFS and LHFI. Trustmark reports unrealized gains and losses resulting from changes in the fair value of the LHFS accounted for under the fair value option as noninterest income in mortgage banking, net. LHFS are actively managed and monitored and certain market risks of the loans may be mitigated through the use of derivatives. These derivative instruments are carried at fair value with changes in the fair value reported as noninterest income in mortgage banking, net. Changes in the fair value of the LHFS are largely offset by changes in the fair value of the derivative instruments. Election of the fair value option allows Trustmark to reduce the accounting volatility that would otherwise result from the asymmetry created by accounting for its LHFS at the lower of cost or fair value and the derivative instruments at fair value. Realized gains and losses upon ultimate sale of the loans are reported as noninterest income in mortgage banking, net. Government National Mortgage Association (GNMA) optional repurchase programs allow financial institutions to buy back individual delinquent mortgage loans that meet certain criteria from the securitized loan pool for which the institution provides servicing. At the servicer’s option and without GNMA’s prior authorization, the servicer may repurchase such a delinquent loan for an amount equal to 100 percent of the remaining principal balance of the loan. Under FASB ASC Topic 860, “Transfers and Servicing,” this buy-back option is considered a conditional option until the delinquency criteria are met, at which time the option becomes unconditional. When Trustmark is deemed to have regained effective control over these loans under the unconditional buy-back option, the loans can no longer be reported as sold and must be brought back onto the balance sheet as LHFS, regardless of whether Trustmark intends to exercise the buy-back option. These loans are reported as LHFS with the offsetting liability being reported as short-term borrowings. The fair value option election does not apply to the GNMA optional repurchase loans which do not meet the requirements under FASB ASC Topic 825 to be accounted for under the fair value option. Trustmark defers the upfront loan fees and costs related to the LHFS. In general, the LHFS are only retained on Trustmark’s balance sheet for 30 to 45 days before they are pooled and sold in the secondary market. The difference between deferring these loan fees and costs until the loans are sold and recognizing them in earnings as incurred as required by FASB ASC Subtopic 825-10 is considered immaterial. Deferred loan fees and costs are reflected in the basis of the LHFS and, as such, impact the resulting gain or loss when the loans are sold.
Loans Held for Investment (LHFI)	Loans Held for Investment (LHFI) LHFI are loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off and are reported at amortized cost net of the allowance for credit losses. Amortized cost is 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. 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. 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, “Receivables-Troubled Debt Restructurings by Creditors.” 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. Purchased Credit Deteriorated (PCD) Loans Trustmark has purchased loans, some of which have experienced more than insignificant credit deterioration since origination. An initial allowance for credit losses for PCD loans is determined at acquisition using the same allowance for credit losses methodology as the LHFI. The initial allowance for credit losses determined on a collective basis is allocated to individual loans. PCD loans are reported at the amortized cost, which equals the loan purchased price plus the initial allowance for credit losses. The difference between the amortized cost basis of the PCD loan and the par value of the loan is the noncredit premium or discount, which is amortized into interest income over the life of the loan. Subsequent changes to the allowance for credit losses are recorded through the PCL. Upon adoption of FASB ASC Topic 326, Trustmark elected to maintain pools of loans that were previously accounted for under FASB ASC Subtopic 310-30, “Receivables-Loans and Debt Securities Acquired with Deteriorated Credit Quality,” and will continue to account for these pools as a unit of account. Loans are only removed from the existing loan pools if they are written off, paid off or sold. Upon adoption of FASB ASC Topic 326, the allowance for credit losses was determined for each pool and added to the pool’s carrying value to establish a new amortized cost basis. The difference between the unpaid principal balance of the pool and the new amortized cost basis is the noncredit premium or discount which will be amortized into interest income over the remaining life of the pool. Changes to the allowance for credit losses after adoption of FASB ASC Topic 326 are recorded through the PCL.
Allowance for Credit Losses, LHFI (ACL)	Allowance for Credit Losses, LHFI (ACL) Trustmark’s ACL methodology for LHFI is based upon guidance within FASB ASC Subtopic 326-20 as well as regulatory guidance from its primary regulator. The ACL is a valuation account that is deducted from the loans’ amortized cost basis to present the net amount expected to be collected on the loans. Credit quality within the LHFI portfolio is continuously monitored by Management and is reflected within the ACL for loans. The ACL is an estimate of expected losses inherent within Trustmark’s existing LHFI portfolio. The ACL for LHFI is adjusted through the PCL and reduced by the charge off of loan amounts, net of recoveries. The loan loss estimation process involves procedures to appropriately consider the unique characteristics of Trustmark’s LHFI portfolio segments. These segments are further disaggregated into loan classes, the level at which credit risk is estimat ed. When computing allowance levels, credit loss assumptions are estimated using a model that categorizes loan pools based on loss history, delinquency status and other credit trends and risk characteristics, including current conditions and reasonable and supportable forecasts about the future. 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. Determining the appropriateness of the allowance is complex and requires judgement by Management about the effect of matters that are inherently uncertain. In future periods , evaluations of the overall LHFI portfolio, in light of the factors and forecasts then prevailing, may result in significant changes in the allowance and credit loss expense. Trustmark estimates the ACL using relevant available information, from internal and external sources, relating to past events, current conditions and reasonable and supportable forecasts including the COVID-19 pandemic effects. Trustmark uses a third-party software application to calculate the quantitative portion of the ACL using a methodology and assumptions specific to each loan pool. The qualitative portion of the 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: lending policies and procedures, economic conditions and concentrations of credit, nature and volume of the portfolio, performance trends, and external factors. The quantitative and qualitative portions of the allowance are added together to determine the total allowance for credit losses, which reflects Management’s expectations of future conditions based on reasonable and supportable forecasts. The methodology for estimating the amount of expected credit losses reported in the ACL has two basic components: a collective, or pooled, component for estimated expected credit losses for pools of loans that share similar risk characteristics, and an asset-specific component involving individual loans that do not share risk characteristics with other loans and the measurement of expected credit losses for such individual loans. In estimating the allowance for credit losses for the collective component, loans are segregated into loan pools based on loan product types and similar risk characteristics. Trustmark determined that reasonable and supportable forecasts could be made for a twelve-month period for all of its loan pools. To the extent the lives of the loans in the LHFI portfolio extend beyond this forecast period, Trustmark uses a reversion period of four quarters and reverts to the historical mean on a straight-line basis over the remaining life of the loans. The ACL for individual loans that do not share risk characteristics with other loans is measured as the difference between the discounted value of expected future cash flows, based in the effective interest rate at origination, and the amortized cost basis of the loan, or the net realizable value. The ACL is the difference between the loan’s net realizable value and its amortized cost basis (net of previous charge-offs and deferred loan fees and costs), except for collateral-dependent loans. A loan is collateral dependent when the borrower is experiencing financial difficulty and repayment of the loan is expected to be provided substantially through the sale of the collateral. The expected credit loss for collateral-dependent loans is measured as the difference between the amortized cost basis of the loan and the fair value of the collateral, adjusted for the estimated cost to sell. Fair value estimates for collateral-dependent loans are derived from appraised values based on the current market value or the ‘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. If the calculated expected credit loss is determined to be permanent or not recoverable, the amount of the expected credit loss is charged off. Accrued interest receivable is not included in the amortized cost basis of Trustmark’s LHFI and, therefore, excluded from the estimate of credit losses for LHFI. LHFI are charged off against the ACL, with any subsequent recoveries credited back to the ACL account. Expected recoveries may not exceed the aggregate of amounts previously charged off and expected to be charged off. Trustmark’s loan policy dictates the guidelines to be followed in determining when a loan is charged off. 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. ACL on Off-Balance Sheet Credit Exposures Under FASB ASC Subtopic 326-20, Trustmark is required to estimate expected credit losses for off-balance sheet credit exposures which are not unconditionally cancellable. Trustmark maintains a separate ACL on off-balance sheet credit exposures, including unfunded loan commitments and letters of credit. Expected credit losses for off-balance sheet credit exposures are estimated by calculating a commitment usage factor over the contractual period for exposures that are not unconditionally cancellable by Trustmark. Trustmark calculates a loan pool level unfunded amount for the period. Trustmark views the loan pools as either closed-ended or open-ended. Closed-ended loan pools are those that typically fund up to 100% such as other construction and nonowner-occupied. Open-ended loan pools are those that behave similar to a revolver such as the commercial and industrial and home equity line of credit loan pools. In addition to the unfunded balances, Trustmark uses a funding rate for loan pools that are considered open-ended. Trustmark calculates the funding rate of the open-ended loan pools each period. In order to mitigate volatility and incorporate historical experience in the funding rate, Trustmark uses a twelve-quarter moving average. For the closed-ended loan pools, Trustmark takes a conservative approach and uses a 100% funding rate. The expected funding rate is applied to each pool’s unfunded commitment balances to ensure that reserves will be applied to each pool based on balances expected to be funded based upon historical levels. In addition to the funding rate being applied to the unfunded commitment balance, a reserve rate is applied that incorporates both quantitative and qualitative aspects of the current period’s expected credit loss rate. The reserve rate is loan pool specific and is applied to the unfunded amount to ensure loss factors, both quantitative and qualitative, are being considered on the unfunded portion of the loan pool, consistent with the methodology applied to the funded loan pools. Adjustments to the ACL on off-balance sheet credit exposures are recorded to credit loss expense related to off-balance sheet credit exposures in noninterest expense. No credit loss estimate is reported for off-balance sheet credit exposures that are unconditionally cancellable by Trustmark or for undrawn amounts under such arrangements that may be drawn prior to the cancellation of the arrangement. ACL, LHFI Trustmark’s ACL methodology for LHFI is based upon guidance within FASB ASC Subtopic 326-20 as well as regulatory guidance from its primary regulator. The ACL is a valuation account that is deducted from the loans’ amortized cost basis to present the net amount expected to be collected on the loans. Credit quality within the LHFI portfolio is continuously monitored by Management and is reflected within the ACL for loans. The ACL is an estimate of expected losses inherent within Trustmark’s existing LHFI portfolio. The ACL for LHFI is adjusted through the PCL and reduced by the charge off of loan amounts, net of recoveries. The methodology for estimating the amount of expected credit losses reported in the ACL has two basic components: a collective, or pooled, component for estimated expected credit losses for pools of loans that share similar risk characteristics, and an asset-specific component involving individual loans that do not share risk characteristics with other loans and the measurement of expected credit losses for such individual loans. In estimating the allowance for credit losses for the collective component, loans are segregated into loan pools based on loan product types and similar risk characteristics. The loans secured by real estate and other loans secured by real estate portfolio segments include loans for both commercial and residential properties. The underwriting process for these loans includes analysis of the financial position and strength of both the borrower and guarantor, experience with similar projects in the past, market demand and prospects for successful completion of the proposed project within the established budget and schedule, values of underlying collateral, availability of permanent financing, maximum loan-to-value ratios, minimum equity requirements, acceptable amortization periods and minimum debt service coverage requirements, based on property type. The borrower’s financial strength and capacity to repay their obligations remain the primary focus of underwriting. Financial strength is evaluated based upon analytical tools that consider historical and projected cash flows and performance in addition to analysis of the proposed project for income-producing properties. Additional support offered by guarantors is also considered. Ultimate repayment of these loans is sensitive to interest rate changes, general economic conditions, liquidity and availability of long-term financing. The commercial and industrial LHFI portfolio segment includes loans within Trustmark’s geographic markets made to many types of businesses for various purposes, such as short term working capital loans that are usually secured by accounts receivable and inventory and term financing for equipment and fixed asset purchases that are secured by those assets. Trustmark’s credit underwriting process for commercial and industrial loans includes analysis of historical and projected cash flows and performance, evaluation of financial strength of both borrowers and guarantors as reflected in current and detailed financial information and evaluation of underlying collateral to support the credit. The consumer LHFI portfolio segment is comprised of loans which are underwritten after evaluating a borrower’s repayment capacity, credit and collateral. Several factors are considered when assessing a borrower’s capacity to repay the obligation, including the borrower’s employment, income, current debt and assets. Credit is assessed using a credit report that provides credit scores and the borrower’s current and past information about their credit history. Property appraisals are obtained to assist in evaluating collateral. Loan-to-value and debt-to-income ratios, loan amount and lien position are also considered in assessing whether to originate a loan. These borrowers are particularly susceptible to downturns in economic trends such as conditions that negatively affect housing prices and demand and levels of unemployment. The state and other political subdivision LHFI and the other commercial LHFI portfolio segments primarily consist of loans to non-depository financial institutions, such as mortgage companies, finance companies and other financial intermediaries, loans to state and political subdivisions, and loans to non-profit and charitable organizations. These loans are underwritten based on the specific nature or purpose of the loan and underlying collateral with special consideration given to the specific source of repayment for the loan. The following table provides a description of each of Trustmark’s portfolio segments, loan classes, loan pools and the ACL methodology and loss drivers: Portfolio Segment Loan Class Loan Pool Methodology Loss Drivers Loans secured by real estate Construction, land development and other land 1-4 family residential construction DCF Prime Rate, National GDP Lots and development DCF Prime Rate, Southern Unemployment Unimproved land DCF Prime Rate, Southern Unemployment All other consumer DCF Prime Rate, Southern Unemployment Other secured by 1-4 family residential properties Consumer 1-4 family - 1st liens DCF Prime Rate, Southern Unemployment All other consumer DCF Prime Rate, Southern Unemployment Nonresidential owner-occupied DCF Southern Unemployment, National GDP Secured by nonfarm, nonresidential properties Nonowner-occupied - hotel/motel DCF Southern Vacancy Rate, Southern Unemployment Nonowner-occupied - office DCF Southern Vacancy Rate, Southern Unemployment Nonowner-occupied- Retail DCF Southern Vacancy Rate, Southern Unemployment Nonowner-occupied - senior living/nursing homes DCF Southern Vacancy Rate, Southern Unemployment Nonowner-occupied - all other DCF Southern Vacancy Rate, Southern Unemployment Nonresidential owner-occupied DCF Southern Unemployment, National GDP Other real estate secured Nonresidential nonowner -occupied - apartments DCF Southern Vacancy Rate, Southern Unemployment Nonresidential owner-occupied DCF Southern Unemployment, National GDP Nonowner-occupied - all other DCF Southern Vacancy Rate, Southern Unemployment Other loans secured by real estate Other construction Other construction WARM Prime Rate, National Unemployment Secured by 1-4 family residential properties Trustmark mortgage WARM Southern Unemployment Commercial and industrial loans Commercial and industrial loans Commercial and industrial - non-working capital DCF Trustmark historical data Commercial and industrial - working capital DCF Trustmark historical data Credit cards WARM Trustmark call report data Consumer loans Consumer loans Credit cards WARM Trustmark call report data Overdrafts Loss Rate Trustmark historical data All other consumer DCF Prime Rate, Southern Unemployment State and other political subdivision loans State and other political subdivision loans Obligations of state and political subdivisions DCF Moody's Bond Default Study Other commercial loans Other commercial loans Other loans DCF Prime Rate, Southern Unemployment Commercial and industrial - non-working capital DCF Trustmark historical data Commercial and industrial - working capital DCF Trustmark historical data In general, Trustmark utilizes a DCF method to estimate the quantitative portion of the allowance for credit losses for loan pools. The DCF model consists of two key components, a loss driver analysis (LDA) and a cash flow analysis. For loan pools utilizing the DCF methodology, multiple assumptions are in place, depending on the loan pool. A reasonable and supportable forecast is utilized for each loan pool by developing a LDA for each loan class. The LDA uses charge off data from Federal Financial Institutions Examination Council (FFIEC) reports to construct a periodic default rate (PDR). The PDR is decomposed into a probability of default (PD). Regressions are run using the data for various macroeconomic variables in order to determine which ones correlate to Trustmark’s losses. These variables are then incorporated into the application to calculate a quarterly PD using a third-party baseline forecast. In addition to the PD, a loss given default (LGD) is derived using a method referred to as Frye Jacobs. The Frye Jacobs method is a mathematical formula that traces the relationship between LGD and PD over time and projects the LGD based on the levels of PD forecasts. This model approach is applicable to all pools within the construction, land development and other land, other secured by 1-4 family residential properties, secured by nonfarm, nonresidential properties and other real estate secured loan classes as well as the all other consumer and other loans pools. For the commercial and industrial loans related pools, Trustmark uses its own PD and LGD data, instead of the macroeconomic variables and the Frye Jacobs method described above, to calculate the PD and LGD as there were no defensible macroeconomic variables that correlated to Trustmark’s losses. Trustmark utilizes a third-party Bond Default Study to derive the PD and LGD for the obligations of state and political subdivisions pool. Due to the lack of losses within this pool, no defensible macroeconomic factors were identified to correlate. The PD and LGD measures are used in conjunction with prepayment data as inputs into the DCF model to calculate the cash flows at the individual loan level. Contractual cash flows based on loan terms are adjusted for PD, LGD and prepayments to derive loss cash flows. These loss cash flows are discounted by the loan’s coupon rate to arrive at the discounted cash flow based quantitative loss. The prepayment studies are updated quarterly by a third-party for each applicable pool. An alternate method of estimating the ACL is used for certain loan pools due to specific characteristics of these loans. For the non-DCF pools, specifically, those using the weighted average remaining maturity (WARM) method, the remaining life is incorporated into the ACL quantitative calculation. Trustmark determined that reasonable and supportable forecasts could be made for a twelve-month period for all of its loan pools. To the extent the lives of the loans in the LHFI portfolio extend beyond this forecast period, Trustmark uses a reversion period of four quarters and reverts to the historical mean on a straight-line basis over the remaining life of the loans. The econometric models in production today reflect segment or pool level sensitivities of PD to changes in macroeconomic variables. By measuring the relationship between defaults and changes in the economy, the quantitative reserve incorporates reasonable and supportable forecasts of future conditions that will affect the value of its assets, as required by FASB ASC Topic 326. Under stable forecasts, these linear regressions will reasonably predict a pool’s PD. However, due to the COVID-19 pandemic, the macroeconomic variables used for reasonable and supportable forecasting have changed rapidly. At the current levels, it is not clear that the models currently in production will produce reasonably representative results since the models were originally estimated using data beginning in 2004 through 2017. During this period, a traditional, albeit severe, economic recession occurred. Thus, econometric models are sensitive to similar future levels of PD. In order to prevent the econometric models from extrapolating beyond reasonable boundaries of their input variables, Trustmark chose to establish an upper and lower limit process when applying the periodic forecasts. In this way, Management will not rely upon unobserved and untested relationships in the setting of the quantitative reserve. This approach applies to all input variables, including: Southern Unemployment, National Unemployment, National GDP, Southern Vacancy Rate and the Prime Rate. The upper and lower limits are based on the distribution of the macroeconomic variable by selecting extreme percentiles at the upper and lower limits of the distribution, the 1st and 99th, respectively. These upper and lower limits are then used to calculate the PD for the forecast time period in which the forecasted values are outside of the upper and lower limit range. For the current period, the forecast related to the macroeconomic variables used in the quantitative modeling process were positively impacted due to the updated forecast effects related to the COVID-19 pandemic, causing an overall decrease in quantitative reserve levels. Qualitative factors used in the ACL methodology include the following: • Lending policies and procedures • Economic conditions and concentrations of credit • Nature and volume of the portfolio • Performance trends • External factors While all these factors are incorporated into the overall methodology, only three are currently considered active: economic conditions and concentrations of credit, performance trends and external factors. Two of Trustmark’s largest loan classes are the loans secured by nonfarm, nonresidential properties and the loans secured by other real estate. Trustmark elected to create a qualitative factor specifically for these loan classes which addresses changes in the economic conditions of metropolitan areas and applies additional pool level reserves. This qualitative factor is based on third-party market data and forecast trends and is updated quarterly as information is available, by market and by loan pool. For the performance trends factor , Trustmark uses migration analyses to allocate additional ACL to non-pass/delinquent loans within each pool. In this way, Management believes the ACL will directly reflect changes in risk , based on the performance of the loans within a pool, whether declining or improving . The external factors qualitative factor is Management’s best judgement on the loan or pool level impact of all factors that affect the portfolio that are not accounted for using any other part of the ACL methodology, e.g., natural disasters, changes in legislation, impacts due to technology and pandemics. During the third quarter of 2020, Trustmark activated the External Factor – Pandemic to ensure reserve adequacy for collectively evaluated loans most likely to be impacted by the unique economic and behavioral conditions created by the COVID-19 pandemic. Additional qualitative reserves are derived based on two principles. The first is the disconnect of economic factors to Trustmark’s modeled probability of default (the econometric models underpinning the quantitative pooled reserves). During the pandemic, extraordinary measures by the federal government were made available to consumers and businesses, including COVID-19 loan payment concessions, direct transfer payments to households, tax deferrals, and reduced interest rates, among others. These government interventions may have extended the lag between economic conditions and default, relative to what was captured in the model development data. Because Trustmark’s econometric PD models rely on the observed relationship from the economic downturn from 2007 to 2009 in both timing and severity, Management does not expect the models to reflect these current conditions. For example, while the models would predict contemporaneous unemployment peaks and loan defaults, this may not occur when borrowers can request payment deferrals. Thus, for the affected population, economic conditions are not fully considered as a part of Trustmark’s quantitative reserve. The second principle is the change in risk that is identified by rating changes. As a part of Trustmark’s credit review process, loans in the affected population have been given more frequent screening to ensure accurate ratings are maintained through this dynamic period. Trustmark’s quantitative reserve does not directly address changes in ratings, thus a migration qualitative factor was designed to work in concert with the quantitative reserve. In a downturn, the qualitative factor is inactive for most pools because changes in ratings are congruent with changes in macroeconomic conditions, which directly influence the PD models in the quantitative reserve. As discussed above, the disconnect of economic factors means that changes in rating caused by deteriorating and weak economic conditions as a result of the pandemic are not being captured in the quantitative reserve. During the fourth quarter due to unforeseen pandemic conditions that varied from Management’s expectations during the third quarter, additional reserves were further dimensioned in order to appropriately reflect the risk within the portfolio related to the COVID-19 pandemic. In an effort to ensure the External Factor-Pandemic qualitative factor is reasonable and supportable, historical Trustmark loss data was leveraged to construct a framework that is quantitative in nature. To dimension the additional reserve, Management uses the sensitivity of the quantitative commercial loan reserve to changes in macroeconomic conditions to apply to loans rated acceptable or better (RR 1-4). In addition, to account for the known changes in risk, a weighted average of the commercial loan portfolio loss rate, derived from the performance trends qualitative factor, is used to dimension additional reserves for downgraded credits. Loans rated acceptable with risk (RR 5) or watch (RR 6) received the additional reserves based on the average of the macroeconomic conditions and weighted- average of the commercial loan portfolio loss rate while the loans rated special mention and substandard received additional reserves based on the weighted-average described above.
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 noninterest 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 recorded at the fair value less cost to sell (estimated fair value) at the time of foreclosure. Fair value is based on independent appraisals and other relevant factors. When foreclosed real estate is received in full satisfaction of a loan, the amount, if any, by which the recorded amount of the loan exceeds the estimated fair value of the property is a loss charged against the ACL at the time of foreclosure. If the recorded amount of the loan is less than the estimated fair value of the property, a credit is recorded to write-downs of other real estate at the time of foreclosure. Other real estate is revalued on an annual basis or more often if market conditions necessitate. An other real estate specific reserve may be recorded through other real estate expense for declines in fair value subsequent to foreclosure based on recent appraisals or changes in market conditions. Subsequent to foreclosure, losses on the periodic revaluation of the property are charged against an existing other real estate specific reserve or as noninterest expense in other real estate expense if a reserve does not exist. Costs of operating and maintaining the properties as well as gains or losses on their disposition are also included in other real estate expense as incurred. Improvements made to properties are capitalized if the expenditures are expected to be recovered upon the sale of the properties.
Leases	Leases ASU 2016-02, “Leases (Topic 842),” became effective for Trustmark on January 1, 2019. Trustmark adopted FASB ASC Topic 842 ASU 2018-11, “Leases (Topic 842): Targeted Improvements” Once Trustmark identifies and determines certain contracts are leases according to FASB ASC Topic 842, Trustmark classifies it as an operating or a finance lease and recognizes a right-of-use asset and a lease liability at the lease commencement date. The lease liability represents the present value of the lease payments that remain unpaid as of the commencement date and the right-of-use asset is the initial lease liability recognized for the lease plus any lease payments made to the lessor at or before the commencement date as well as any initial direct costs less any lease incentives received. Trustmark’s finance leases consist of building and equipment leases. Trustmark recognizes interest expense based on the discount rate of the lease as interest expense in other interest expense and recognizes depreciation expense on a straight-line basis over the lease term as noninterest expense in net occupancy – premises for building leases and in equipment expense for equipment leases. Trustmark amortizes the right-of-use asset over the life of the lease term on a straight-line basis. Trustmark’s lease liabilities are measured as the present value of the remaining lease payments throughout the lease term. Trustmark records its finance lease right-of-use assets in premises and equipment, net and its finance lease liabilities in other borrowings. Trustmark’s operating leases primarily consist of building and land leases. Trustmark recognizes lease rent expense on a straight-line basis over the term of the lease contract and records it as noninterest expense in net occupancy – premises for building and land leases and in equipment expense for equipment leases. Trustmark’s amortization of the right-of-use asset is the difference between the straight-line lease expense and the interest expense recognized on the lease liability during the period. Trustmark’s lease liabilities are measured as the present value of the remaining lease payments throughout the lease term. Trustmark’s leases typically have one or more renewal options included in the lease contract. Due to the nature of Trustmark’s leases, for leases with renewal options available, Trustmark considers the first renewal option as reasonably certain to renew and is therefore included in the measurement of the right-of-use assets and lease liabilities. In order to calculate its right-of-use assets and lease liabilities, FASB ASC Topic 842 requires Trustmark to use the rate of interest implicit in the lease when readily determinable. If the rate implicit in the lease is not readily determinable, Trustmark is required to use its incremental borrowing rate, which is the rate of interest Trustmark would have to pay to borrow on a collateralized basis over a similar term in a similar economic environment. Trustmark was able to determine the implicit interest rate for its equipment leases and used that rate as its discount rate. Since the implicit interest rate for most of its building and land leases were not readily determinable, Trustmark used its incremental borrowing rate. Trustmark’s short-term leases primarily include automated teller machines. For short-term leases, Trustmark recognizes lease expense on a straight-line basis over the lease term. As previously stated, Trustmark has elected not to include short-term leases on its balance sheet.
Federal Home Loan Bank (FHLB) and Federal Reserve Bank of Atlanta Stock	Federal Home Loan Bank (FHLB) and Federal Reserve Bank of Atlanta Stock Trustmark accounts for its investments in FHLB and Federal Reserve Bank of Atlanta stock in accordance with FASB ASC Subtopic 942-325, “Financial Services-Depository and Lending-Investments-Other.” FHLB and Federal Reserve Bank stock are equity securities that do not have a readily determinable fair value because its ownership is restricted and it lacks a market. FHLB and Federal Reserve Bank stock are carried at cost and evaluated for impairment. Trustmark’s investment in member bank stock is included in other assets in the accompanying consolidated balance sheets. At December 31, 2020 and 2019, Trustmark’s investment in member bank stock totaled $31.7 million and $31.9 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, 2020, 2019 and 2018.
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, 2020 resulted in a net gain of $897 thousand compared to a net loss of $291 thousand for the year ended December 31, 2019 and a net gain of $700 thousand for the year ended December 31, 2018. In general, purchases of Trustmark’s other real estate property are not financed by Trustmark. Financing the purchase of other real estate is evaluated based upon the same lending policies and procedures as all other types of loans. Under FASB ASC Subtopic 610-20, “Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets,” when Trustmark finances the sale of its other real estate to a buyer, Trustmark is required to assess whether the buyer is committed to perform their obligations under the contract and whether collectability of the transaction price is probable. Once these two criteria are met, Trustmark derecognizes the other real estate asset and records a gain or loss on the sale once control of the property is transferred to the buyer. Wealth Management Segment Trust Management There are five categories of revenue included in trust management: personal trust and investments, retirement plan services, institutional custody, corporate trust and other. Each of these categories includes multiple types of contracts, service obligations and fee income. However, the majority of these contracts include a single service obligation that is satisfied over time, the customer is charged in arrears for services rendered and revenue is recognized when payment is received. In general, the time period between when the service obligation is completed and when payment from the customer is received is less than 30 days. Revenue from trust management contracts is primarily related to monthly service periods and based on the prior month-end’s market value. Some trust management revenue is mandated by a court order, while other revenue consists of flat fees. Trust management revenue based on an account’s market value represents variable consideration under the guidelines of FASB ASC Topic 606. Trustmark has elected the ‘as-invoiced’ practical expedient allowed under FASB ASC Topic 606 to account for the trust management revenue. Assets under administration held by Trustmark in a fiduciary or agency capacity for customers are not included in Trustmark’s consolidated balance sheets. Investment Services Investment services includes both brokerage and annuity income. Trustmark has a contract with a third-party investment services company which contains a single continuous service obligation, to provide broker-dealer and advisory services to customers on behalf of the third-party, which is satisfied over time and qualifies as a series of distinct service periods. Trustmark serves as the agent between the third-party investment services company, the principle, and the customer. In accordance with the contract, Trustmark receives a monthly payment from the investment services company for commissions and advisory fees (asset management fees) earned on transactions completed in the prior month net of all charges and fees due to the investment services company. Trustmark recognizes revenue from the investment services company, net of the revenue sharing expense due to the investment services company, when the payments are received. Commissions vary from month-to-month based on the specific products and transactions completed. The advisory fees vary based on the average daily balance of the managed assets for the period. The commissions and advisory fees represent variable consideration under FASB ASC Topic 606. Trustmark has elected the ‘as-invoiced’ practical expedient allowed under FASB ASC Topic 606 to recognize revenue from the investment services company. Insurance Segment Fisher Brown Bottrell Insurance, Inc. (FBBI), a wholly-owned subsidiary of Trustmark National Bank (TNB), operates as an insurance broker representing the policyholder and has no allegiance with any one insurance provider. FBBI serves as the agent between the insurance provider (either insurance carrier or broker), the principal, and the policy holder, the customer. FBBI has four general categories of insurance contracts: commercial, commercial installments, personal and employee benefits. FBBI’s insurance contracts contain a single performance obligation, policy placement, which is satisfied at a point in time. FBBI’s performance obligation is satisfied as of the policy effective date. In addition to policy placement, FBBI provides various other periodic services to the policyholders for which no additional fee is charged. These additional services are not considered material to the overall contract. Trustmark has elected the immaterial promises practical expedient allowed under FASB ASC Topic 606, which allows Trustmark to not assess whether promised services are performance obligations if the promised services are immaterial in the context of the contract. Therefore, the immaterial additional services offered to policyholders are not considered a performance obligation and no amount of the contract transaction price is allocated to these services. In general, the transaction price for the insurance contracts is an established commission amount agreed upon by FBBI and the insurance provider. The commission amount varies based on the insurance provider and the type of policy. There are a small number of insurance contracts which FBBI does not receive a commission, but charges a fee directly to the policyholder. Most of the commissions from insurance contracts are subject to clawback provisions which require FBBI to refund a prorated amount of the commissions received as a result of policy cancellations or lapses. Commissions subject to clawback provisions are considered variable consideration under FASB ASC Topic 606. Trustmark believes the expected value method of estimating the commissions subject to clawback provisions would best predict the amount of commissions FBBI will be entitled to because of the large number of insurance contracts with similar characteristics and the number of possible outcomes. FBBI calculates a separate weighted-average percentage (returned commissions percentage) based on actual cancellations over the previous three years for commercial lines, bonds, and personal lines. FBBI applies the respective returned commissions percentage to the commission revenue earned related to insurance contracts within these three lines each month to calculate the estimated returned commissions amount, which represents the variable consideration subject to variable constraint. Revenue from insurance contracts is reported net of the variable consideration subject to variable constraint. FBBI performs an analysis of the returned commissions reserve quarterly and adjusts the reserve balance based on all available information including actual cancellations and the remaining term of the contract. The returned commission percentage is updated annually. Insurance Producers at FBBI earn commission as compensation for each policy they are responsible for placing. Commissions are not paid to Producers immediately at the policy effective date, can be subject to clawback provisions and can vary by Producer. Effective April 1, 2018, FBBI implemented a ‘pay when paid’ system. Under the ‘pay when paid’ system, Producers receive the commissions for which they are entitled at the end of the month following the month in which FBBI receives payment from the insurance provider or customer. Under FASB ASC Subtopic 340-40, “Other Assets and Deferred Costs: Contracts with Customers,” the commission paid to the Producers is an incremental cost of obtaining a contract, which should be capitalized and amortized in a manner consistent with the pattern of transfer of the service related to the contract acquisition asset. Insurance contracts have a term of one year or less; therefore, Trustmark has elected the cost of obtaining a contract practical expedient allowed under FASB ASC Subtopic 340-40, which allows FBBI to recognize the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the contract asset that FBBI otherwise would have recognized is one year or less. Commission expense is recorded as noninterest expense in salaries and employee benefits when paid to the Producers. Commercial Insurance Revenue from FBBI’s commercial insurance contracts (both agency billed and direct billed) consists of a set commission amount, which is subject to clawback provisions. Revenue from commercial installment insurance contracts consists of a set commission amount, which is not subject to clawback provisions. An estimated commission amount is entered in the agency management system when a commercial insurance contract is placed. FBBI records a top line receivable based on the estimated commission amount entered in the system each month, along with a corresponding amount recognized as revenue, and then adjusts the estimated receivable when the commissions are received from the insurance provider or customer. Personal Insurance Revenue from FBBI’s personal insurance contracts consists of a set commission amount, which is subject to clawback provisions, and is recognized when payment is received (generally 30-60 days after the policy effective date). Personal insurance contracts have a term of one year; therefore, recognizing the revenue from these contracts when payment is received is not materially different than recognizing the revenue at the policy effective date for any given period. Employee Benefits Insurance Revenue from FBBI’s employee benefits insurance contracts consists of a variable commission amount, which is not subject to clawback provisions, and is recognized when payment is received, typically on a monthly basis. Employee benefits insurance contracts have a set commission rate, but can vary from period to period based on changes in the number of employees covered by the policy (i.e. new hires and terminations). FBBI generally receives twelve monthly commission payments for these contracts with the initial payment being received approximately 60-90 days after the policy effective date. Under the guidelines of FASB ASC Topic 606, commissions from employee benefits insurance contracts represent fixed consideration because at contract inception (policy effective date) there is a set commission rate times a known number of covered employees. Changes in the number of covered employees are not known, nor can they be predicted, at contract inception. An increase or decrease in the number of covered employees after the policy effective date is considered a contract modification resulting from a change in scope and transaction price under FASB ASC Topic 606. This modification is treated as part of the existing contract because it does not add a distinct service. Employee benefits insurance contracts have a term of one year ; therefore, recognizing the revenue from these contracts when payment is received is not materially different than recognizing the revenue at the policy effective date or the contract modification date for any given period. Contingency Commission Insurance In addition to the insurance contracts discussed above, FBBI has contracts with various insurance providers for which it receives contingency income based on volume of business and claims experience. FBBI is the principal and the insurance provider is the customer for these contingency commission insurance contracts. The contingency commission contracts have a single continuous or stand-ready service obligation whereby FBBI places policies with policyholders when acceptable to the insurance provider, which is satisfied over time. The contract term for these contingency commission contracts is one year. Revenue is recognized from the contingency commission contracts monthly using a time-elapsed measure of progress. FBBI accrues throughout the current year the amount of contingency commission income it expects to receive in the following year adjusted for a degree of uncertainty. FBBI updates a detail by insurance provider with the contingency commission income received, which is then compared to the total amount that was expected to be received. If actual receipts are higher or lower than the amount accrued in the prior year, the monthly accrual for the current year is adjusted accordingly. Under the guidelines of FASB ASC Topic 606, revenue from contingency commission insurance contracts represents variable consideration and should be estimated using one of the two allowable methods subject to the variable consideration constraint. FBBI believes the most likely amount method to be the most appropriate method for estimating the variable consideration as there are only a few possible outcomes for each contract.
Derivative Financial Instruments	Derivative Financial Instruments Trustmark maintains an overall interest rate risk management strategy that incorporates the use of derivative instruments to minimize significant unplanned fluctuations in earnings and cash flows caused by interest rate volatility. Trustmark’s interest rate risk management strategy involves modifying the repricing characteristics of certain assets and liabilities so that changes in interest rates do not adversely affect the net interest margin and cash flows. Under the guidelines of FASB ASC Topic 815, “Derivatives and Hedging,” all derivative instruments are required to be recognized as either assets or liabilities and carried at fair value on the balance sheet. The fair value of derivative positions outstanding is included in other assets and/or other liabilities in the accompanying consolidated balance sheets and in the net change in these financial statement line items in the accompanying consolidated statements of cash flows as well as included in noninterest income in the accompanying consolidated statements of income and other comprehensive income (loss), net of tax in the accompanying consolidated statements of comprehensive income. Trustmark’s interest rate swap derivative instruments are subject to master netting agreements, and therefore, eligible for offsetting in the consolidated balance sheets. Trustmark has elected to not offset any derivative instruments in its consolidated balance sheets. Derivatives 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. The Chicago Mercantile Exchange rules legally characterize variation margin collateral payments made or received for centrally cleared interest rate swaps as settlements rather than collateral. As a result, centrally cleared interest rate swaps included in other assets and other liabilities are presented on a net basis i n the accompanying consolidated balance sheets.
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, 2020 2019 2018 Income taxes paid $ 46,648 $ 24,809 $ 12,435 Interest paid on deposits and borrowings 42,968 83,997 66,358 Noncash transfers from loans to other real estate 635 8,598 12,115 Investment in tax credit partnership not funded 5,893 5,000 — Finance right-of-use assets resulting from lease liabilities — 9,326 — Operating right-of-use assets resulting from lease liabilities 3,774 31,182 — Transfer of long-term FHLB advances to short-term 651 — —
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, 2020 2019 2018 Basic shares 63,505 64,630 67,505 Dilutive shares 141 142 154 Diluted shares 63,646 64,772 67,659 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, 2020 2019 2018 Weighted-average antidilutive stock awards 57 — 1
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 Policy Text Block	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 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” Issued in March 2020, ASU 2020-04 seeks to provided additional guidance, for a limited time, to ease the potential burden in accounting for or recognizing the effects of reference rate reform on financial reporting. The FASB issued ASU 2020-04 is response to concerns about the structural risks of interbank offered rates and, in particular, the risk that the London Interbank Offer Rate (LIBOR) will no longer be used. Regulators have begun reference rate reform initiatives to identify alternative reference rates that are more observable or transaction-based and less susceptible to manipulation. Stakeholders have raised operational challenges likely to arise with the reference rate reform, particularly related to contract modifications and hedge accounting. The amendments of ASU 2020-04, which are elective and apply to all entities, provide expedients and exceptions for applying GAAP to contract modifications and hedging relationships affected by the reference rate reform id certain criteria are met. The amendments apply only to contracts and hedging relationships that reference LIBOR or another reference rate that is expected to be discontinued due to reference rate reform. The optional expedients for contract modifications should be applied consistently for all contracts or transactions within the relevant Codification Topic or Subtopic or Industry Subtopic that contains the related guidance. The optional expedients for hedging relationships can be elected on an individual hedging relationship basis. As the guidance in ASU 2020-04 is intended to assist entity’s during the global market-wide reference rate transition period, it is in effect for a limited time, from March 12, 2020 through December 31, 2022. On January 7, 2021, the FASB issued ASU 2021-01, “Reference Rate Reform (Topic 848): Scope,” to clarify the scope of the reference rate reform guidance in FASB ASC Topic 848. ASU 2021-01 refines the scope of FASB ASC Topic 848 to clarify that certain optional expedients and exceptions therein for contract modifications and hedge accounting apply to contracts that are affected by the discounting transition. Specifically, modifications related to reference rate reform would not be considered an event that requires reassessment of previous accounting conclusions. The amendments in ASU 2021-01 also amend the expedients and exceptions in FASB ASC Topic 848 to capture the incremental consequences of the scope clarification and to tailor the existing guidance to derivative instruments affected by the discounting transition. The amendments of ASU 2021-01 were effective immediately when issued. Entities may choose to apply the amendments of ASU 2021-01 retrospectively as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively to new modifications from any date within an interim period that includes or is subsequent to January 7, 2021, up to the date that financial statements are available to be issued. If an entity elects to apply any of the amendments in this ASU for an eligible hedging relationship, any adjustments as a result of those elections must be reflected as of the date that the entity applies the election. Management is currently evaluating the impact to Trustmark as a result of the potential discontinuance of LIBOR, and a determination cannot be made at this time as to the impact the amendments of ASU 2020-04 and ASU 2021-01 or the reference rate reform will have on its consolidated financial statements. ASU 2018-15, “Intangibles-Goodwill and Other–Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force).” Issued in August 2018, ASU 2018-15 aims to reduce complexity in the accounting for costs of implementing a cloud computing service arrangement. ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The amendments of ASU 2018-15 require an entity to follow the guidance in FASB ASC Subtopic 350-40, “Intangibles-Goodwill and Other-Internal-Use Software,” in order to determine which implementation costs to capitalize as an asset related to the service contract and which costs to expense. The amendments of ASU 2018-15 also require an entity to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement (i.e. the noncancellable period of the arrangement plus periods covered by (1) an option to extend the arrangement if the entity is reasonably certain to exercise that option, (2) an option to terminate the arrangement if the entity is reasonably certain not to exercise the option, and (3) an option to extend (or not to terminate) the arrangement in which exercise of the option is in the control of the vendor). ASU 2018-15 also requires an entity to present the expense related to the capitalized implementation costs in the same line item in the statement of income as the fees associated with the hosting element (service) of the arrangement, and to classify payments for capitalized implementation costs in the statement of cash flows in the same manner as payments made for fees associated with the hosting element. ASU 2018-15 became effective for Trustmark on January 1, 2020. Trustmark does not currently have any material amount of implementation costs related to hosting arrangements that are service contracts within the scope of this ASU; therefore, adoption of ASU 2018-15 did not impact Trustmark’s consolidated financial statements. ASU 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement.” Issued in August 2018, the amendments in this ASU remove disclosure requirements in FASB ASC Topic 820 related to (1) the amount of, and reasons for, transfers between Level 1 and Level 2 of the fair value hierarchy; (2) the policy for timing of transfers between levels; (3) the valuation processes for Level 3 fair value measurements; and (4) for non-public entities, the changes in unrealized gains and losses for the period included in earnings for recurring Level 3 fair value measurements held at the end of the reporting period. The ASU also modifies disclosure requirements such that (1) in place of a rollforward for Level 3 fair value measurements, a non-public entity is required to disclose transfers into and out of Level 3 of the fair value hierarchy and purchases and issues of Level 3 assets and liabilities; (2) for investments in certain entities that calculate net asset value, an entity is required to disclose the timing of liquidation of an investee’s assets and the date that restrictions from redemption might lapse, only if the investee has communicated the timing to the entity or announced the timing publicly; and (3) it is clear that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date. Additionally, this ASU adds disclosure requirements for public entities about (1) the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period, and (2) the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The amendments of ASU 2018-13 became effective for Trustmark on January 1, 2020. Adoption of ASU 2018-13 did not have a material impact on Trustmark’s consolidated financial statements. Disclosures required by FASB ASC Topic 820 are presented in Note 19 – Fair Value, of this report. ASU 2017-04, “ Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” Issued in January 2017, ASU 2017-04 simplifies the manner in which an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit's goodwill with the carrying amount of that goodwill. In computing the implied fair value of goodwill under Step 2, an entity, prior to the amendments in ASU 2017-04, had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities, including unrecognized assets and liabilities, in accordance with the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. However, under the amendments in ASU 2017-04, an entity should (1) perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, and (2) recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value, with the understanding that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, ASU 2017-04 removes the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails such qualitative test, to perform Step 2 of the goodwill impairment test. ASU 2017-04 became effective for Trustmark on January 1, 2020 . Based on Trustmark’s annual goodwill impairment test performed as of October 1, 2020, the fair value of its reporting units exceeded the carrying value and, therefore, the related goodwill was not impaired. ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” Issued in June 2016, ASU 2016-13 will add FASB ASC Topic 326, “Financial Instruments-Credit Losses” and finalizes amendments to FASB ASC Subtopic 825-15, “Financial Instruments-Credit Losses.” The amendments of ASU 2016-13 are intended to provide financial statement users with more decision-useful information related to expected credit losses on financial instruments and other commitments to extend credit by replacing the current incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. The amendments of ASU 2016-13 eliminate the probable initial recognition threshold and, in turn, reflect an entity’s current estimate of all expected credit losses. ASU 2016-13 does not specify the method for measuring expected credit losses, and an entity is allowed to apply methods that reasonably reflect its expectations of the credit loss estimate. Additionally, the amendments of ASU 2016-13 require that credit losses on available for sale debt securities be presented as an allowance rather than as a write-down. The amendments of ASU 2016-13, and all subsequent ASUs issued by FASB to provide additional guidance and clarification related to this Topic, became effective for Trustmark on January 1, 2020. As previously disclosed, Trustmark established a cross-functional Current Expected Credit Loss (CECL) Steering Committee, a CECL Solution Development Working Group and a CECL Working Group which included the appropriate members of Management to evaluate the impact this ASU, and all subsequent ASUs issued by FASB, will have on Trustmark’s financial position, results of operations and financial statement disclosures and determine the most appropriate method of implementing the amendments in these ASUs as well as any resources needed to implement the amendments. Trustmark selected a third-party vendor to provide allowance for loan loss software as well as advisory services in developing a new methodology that would be compliant with amendments of ASU 2016-13. In accordance with the amendments of ASU 2016-13, Trustmark elected to maintain pools of loans that were previously accounted for under FASB ASC Subtopic 310-30 and will continue to account for these pools as a unit of account. Loans are only removed from the existing loan pools if they are written off, paid off or sold. Upon adoption of ASU 2016-13, the allowance for credit losses was determined for each pool and added to the pool’s carrying value to establish a new amortized cost basis. The difference between the unpaid principle balance of the pool and the new amortized cost basis is the noncredit premium or discount which will be amortized into interest income over the remaining life of the pool. As a result of adopting the amendments of ASU 2016-13, Trustmark recorded a decrease to its ACL, LHFI of $3.0 million and an increase to its ACL on off-balance sheet credit exposures of $29.6 million resulting in a one-time cumulative effect adjustment through retained earnings of $26.6 million ($19.9 million, net of tax) at the date of adoption. This adjustment included a qualitative adjustment to the allowance for credit losses related to loans and an allowance on off-balance sheet credit exposures. Trustmark estimates losses over an approximate one-year forecast period using Moody’s baseline economic forecasts, and then reverts to longer term historical loss experience over a one-year period. Trustmark’s estimated allowance for credit losses on both held to maturity securities and available for sale securities under the CECL model was deemed immaterial due to the composition of the portfolios being primarily government agency-backed securities for which the risk of loss is minimal. Therefore, Trustmark did not recognize a cumulative effective adjustment through retained earnings at the date of adoption related to the held to maturity or available for sale securities. Disclosures required by the amendments ASU 2016-13 are presented in Note 3 – Securities Available for Sale and Held to Maturity, Note 4 – LHFI and Allowance for Credit Losses, LHFI and Note 17 – Commitments and Contingencies-Lending Related of this report. Pending Accounting Pronouncements ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” Issued in December 2019, ASU 2019-12 seeks to simplify the accounting for income taxes by removing certain exceptions to the general principles in FASB ASC Topic 740. In particular, the amendments of ASU 2019-12 remove the exceptions to (1) the incremental approach for intra-period tax allocation when there is a loss from continuing operations and income or a gain from other items (e.g., discontinued operations or other comprehensive income); (2) the requirement to recognize a deferred tax liability for equity method investments when a foreign subsidiary becomes an equity method investment; (3) the ability not to recognize a deferred tax liability for a foreign subsidiary when a foreign equity method investment becomes a subsidiary; and (4) the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. The amendments of ASU 2019-12 (1) require that an entity recognize a franchise tax (or similar tax), that is partially based on income, in accordance with FASB ASC Topic 740 and account for any incremental amount incurred as a non-income-based tax; (2) require that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should instead be considered a separate transaction; (3) specify that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements, but rather may elect to do so for a legal entity that is both not subject to tax and disregarded by the taxing authority; and (4) require that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date. Trustmark adopted the amendments of ASU 2019-12 effective January 1, 2021 . Adoption of ASU 2019-12 did not have a material impact to Trustmark’s consolidated financial statements. ASU 2018-14, “Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans.” Issued in August 2018, ASU 2018-14 modifies the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The amendments in ASU 2018-14 remove certain disclosure requirements that are no longer considered cost beneficial, clarify the specific requirements of disclosures and add disclosure requirements identified as relevant. Trustmark adopted the amendments of ASU 2018-14 effective January 1, 2021. Trustmark will include the revised disclosures in its Annual Report on Form 10-K for the year ending December 31, 2021. Changes to the disclosures related to the defined benefit plans as a result of adopting ASU 2018-14 will not have a material impact to Trustmark’s consolidated financial statements

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 2018 Income taxes paid $ 46,648 $ 24,809 $ 12,435 Interest paid on deposits and borrowings 42,968 83,997 66,358 Noncash transfers from loans to other real estate 635 8,598 12,115 Investment in tax credit partnership not funded 5,893 5,000 — Finance right-of-use assets resulting from lease liabilities — 9,326 — Operating right-of-use assets resulting from lease liabilities 3,774 31,182 — Transfer of long-term FHLB advances to short-term 651 — —
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, 2020 2019 2018 Basic shares 63,505 64,630 67,505 Dilutive shares 141 142 154 Diluted shares 63,646 64,772 67,659
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, 2020 2019 2018 Weighted-average antidilutive stock awards 57 — 1

Securities Available for Sale_2

Securities Available for Sale and Held to Maturity (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 and 2019 ($ 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, 2020 Cost Gains Losses Value Cost Gains Losses Value U.S. Government agency obligations $ 18,378 $ 144 $ (481 ) $ 18,041 $ — $ — $ — $ — Obligations of states and political subdivisions 5,198 637 — 5,835 26,584 258 (3 ) 26,839 Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 55,193 1,672 (3 ) 56,862 7,598 382 — 7,980 Issued by FNMA and FHLMC 1,421,861 20,768 (1,308 ) 1,441,321 67,944 2,397 — 70,341 Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 409,883 9,600 (46 ) 419,437 360,361 19,678 (55 ) 379,984 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 49,260 1,068 (9 ) 50,319 75,585 2,386 — 77,971 Total $ 1,959,773 $ 33,889 $ (1,847 ) $ 1,991,815 $ 538,072 $ 25,101 $ (58 ) $ 563,115 December 31, 2019 U.S. Government agency obligations $ 22,965 $ 69 $ (707 ) $ 22,327 $ 3,781 $ 220 $ — $ 4,001 Obligations of states and political subdivisions 24,952 513 — 25,465 31,781 434 (53 ) 32,162 Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 69,196 425 (369 ) 69,252 10,820 266 (10 ) 11,076 Issued by FNMA and FHLMC 714,350 2,171 (3,165 ) 713,356 96,631 286 (370 ) 96,547 Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 656,162 3,777 (1,713 ) 658,226 485,324 7,026 (656 ) 491,694 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 113,359 625 (206 ) 113,778 109,762 1,042 (82 ) 110,722 Total $ 1,600,984 $ 7,580 $ (6,160 ) $ 1,602,404 $ 738,099 $ 9,274 $ (1,171 ) $ 746,202
Securities Held to Maturity by Credit Rating, as Determined by Moody's	The following table presents the amortized cost of Trustmark’s securities held to maturity by credit rating, as determined by Moody’s, at December 31, 2020 ($ in thousands): December 31, 2020 Aaa $ 511,488 Aa1 to Aa3 22,528 Not Rated (1) 4,056 Total $ 538,072 (1) Not rated securities primarily consist of Mississippi municipal general obligations.
Securities with Gross Unrealized Losses, Segregated by Length of Impairment	The table below includes securities with gross unrealized losses for which an allowance for credit losses has not been recorded and segregated by length of impairment at December 31, 2020 and 2019 ($ in thousands): Less than 12 Months 12 Months or More Total Gross Gross Gross Estimated Unrealized Estimated Unrealized Estimated Unrealized December 31, 2020 Fair Value Losses Fair Value Losses Fair Value Losses U.S. Government agency obligations $ — $ — $ 11,167 $ (481 ) $ 11,167 $ (481 ) Obligations of states and political subdivisions — — 667 (3 ) 667 (3 ) Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 1,636 (3 ) — — 1,636 (3 ) Issued by FNMA and FHLMC 324,905 (1,308 ) — — 324,905 (1,308 ) Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 29,398 (101 ) — — 29,398 (101 ) Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA — — 659 (9 ) 659 (9 ) Total $ 355,939 $ (1,412 ) $ 12,493 $ (493 ) $ 368,432 $ (1,905 ) December 31, 2019 U.S. Government agency obligations $ 6,585 $ (105 ) $ 12,886 $ (602 ) $ 19,471 $ (707 ) Obligations of states and political subdivisions — — 6,216 (53 ) 6,216 (53 ) Mortgage-backed securities Residential mortgage pass-through securities Guaranteed by GNMA 23,544 (107 ) 18,529 (272 ) 42,073 (379 ) Issued by FNMA and FHLMC 112,879 (230 ) 278,120 (3,305 ) 390,999 (3,535 ) Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 158,341 (738 ) 151,271 (1,631 ) 309,612 (2,369 ) Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 51,312 (167 ) 14,155 (121 ) 65,467 (288 ) Total $ 352,661 $ (1,347 ) $ 481,177 $ (5,984 ) $ 833,838 $ (7,331 )
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, 2020, 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 $ 1,570 $ 1,604 $ 19,237 $ 19,374 Due after one year through five years 1,527 1,570 7,347 7,465 Due after five years through ten years 2,031 1,989 — — Due after ten years 18,448 18,713 — — 23,576 23,876 26,584 26,839 Mortgage-backed securities 1,936,197 1,967,939 511,488 536,276 Total $ 1,959,773 $ 1,991,815 $ 538,072 $ 563,115

Loans Held for Investment (LH_2

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI (Tables)	12 Months Ended
	Dec. 31, 2020
Accounts Notes Loans And Financing Receivable Gross Allowance And Net [Abstract]
Loan Portfolio Held for Investment	At December 31, 2020 and 2019, LHFI consisted of the following ($ in thousands): December 31, 2020 2019 Loans secured by real estate: Construction, land development and other land (1) $ 514,056 $ 1,162,791 Other secured by 1-4 family residential properties (1) 524,732 1,855,913 Secured by nonfarm, nonresidential properties 2,709,026 2,475,245 Other real estate secured 1,065,964 724,480 Other loans secured by real estate: (1) Other construction 794,983 — Secured by 1-4 family residential properties 1,216,400 — Commercial and industrial loans 1,309,078 1,477,896 Consumer loans 164,386 175,738 State and other political subdivision loans 1,000,776 967,944 Other commercial loans (1) 525,123 495,621 LHFI 9,824,524 9,335,628 Less ACL 117,306 84,277 Net LHFI $ 9,707,218 $ 9,251,351 (1) In accordance with the guidance in FASB ASC Topic 326, Trustmark redefined its LHFI portfolio segments and related loan classes based on the level at which risk is monitored within the ACL methodology. The other loans secured by real estate portfolio segment and related loan classes were separated from the loans secured by real estate portfolio segment. The other construction loans were segregated from the construction, land development and other land loans. The other loans secured by 1-4 family residential properties were segregated from the loans secured by 1-4 family residential properties and the loans secured by 1-4 family residential properties were redefined in the other loans secured by real estate portfolio segment. Other loans were redefined as other commercial loans.
Schedule of Amortized Cost Basis of Loans on Nonaccrual Status	The following table provides the amortized cost basis of loans on nonaccrual status and loans past due 90 days or more still accruing interest as of December 31, 2020 ($ in thousands): December 31, 2020 Nonaccrual With No ACL Total Nonaccrual Loans Past Due 90 Days or More Still Accruing Loans secured by real estate: Construction, land development and other land $ 5,756 $ 5,985 $ — Other secured by 1-4 family residential properties 1,895 4,487 79 Secured by nonfarm, nonresidential properties 12,037 15,197 — Other real estate secured 60 185 — Other loans secured by real estate: Other construction — — — Secured by 1-4 family residential properties — 11,807 1,257 Commercial and industrial loans 12,665 15,618 — Consumer loans — 86 240 State and other political subdivision loans — 3,970 — Other commercial loans — 5,793 — Total $ 32,413 $ 63,128 $ 1,576
Aging Analysis of Past Due and Nonaccrual LHFI by Loan Type	The following table provides an aging analysis of the amortized cost basis of past due LHFI at December 31, 2020 ($ in thousands): December 31, 2020 Past Due 90 Days Total Past Current 30-59 Days 60-89 Days or More Due Loans Total Loans secured by real estate: Construction, land development and other land $ 339 $ 34 $ 161 $ 534 $ 513,522 $ 514,056 Other secured by 1-4 family residential properties 1,505 523 896 2,924 521,808 524,732 Secured by nonfarm, nonresidential properties 920 — 972 1,892 2,707,134 2,709,026 Other real estate secured 103 101 107 311 1,065,653 1,065,964 Other loans secured by real estate: Other construction — — — — 794,983 794,983 Secured by 1-4 family residential properties 3,291 1,289 5,110 9,690 1,206,710 1,216,400 Commercial and industrial loans 271 196 1,543 2,010 1,307,068 1,309,078 Consumer loans 926 190 240 1,356 163,030 164,386 State and other political subdivision loans 117 — 177 294 1,000,482 1,000,776 Other commercial loans 2,143 2,971 346 5,460 519,663 525,123 Total $ 9,615 $ 5,304 $ 9,552 $ 24,471 $ 9,800,053 $ 9,824,524 The following table provides an aging analysis of past due and nonaccrual LHFI by loan class at December 31, 2019 ($ in thousands): December 31, 2019 Past Due 90 Days Current 30-59 Days 60-89 Days or More (1) Total Nonaccrual Loans Total Loans secured by real estate: Construction, land development and other land $ 380 $ 256 $ — $ 636 $ 897 $ 1,161,258 $ 1,162,791 Secured by 1-4 family residential properties 5,254 940 211 6,405 16,810 1,832,698 1,855,913 Secured by nonfarm, nonresidential properties 1,698 — — 1,698 7,700 2,465,847 2,475,245 Other real estate secured 8 — — 8 1,032 723,440 724,480 Commercial and industrial loans 617 12 39 668 21,775 1,455,453 1,477,896 Consumer loans 2,208 380 392 2,980 108 172,650 175,738 State and other political subdivision loans 76 — — 76 4,079 963,789 967,944 Other loans 152 4 — 156 825 494,640 495,621 Total $ 10,393 $ 1,592 $ 642 $ 12,627 $ 53,226 $ 9,269,775 $ 9,335,628 (1) Past due 90 days or more but still accruing interest.
Impaired Financing Receivables	At December 31, 2019, individually evaluated impaired LHFI consisted of the following ($ in thousands): December 31, 2019 LHFI Unpaid Wit h o With an Total Average Principal Allowance Allowance Carrying Related Recorded Balance Recorded Recorded Amount Allowance Investment Loans secured by real estate: Construction, land development and other land $ 926 $ 610 $ 16 $ 626 $ — $ 1,089 Secured by 1-4 family residential properties 6,513 2,104 3,360 5,464 35 4,713 Secured by nonfarm, nonresidential properties 7,295 1,462 5,255 6,717 2,355 8,096 Other real estate secured 69 — 68 68 — 158 Commercial and industrial loans 27,178 19,374 4,084 23,458 707 27,088 Consumer loans 22 — 21 21 — 11 State and other political subdivision loans 4,079 — 4,079 4,079 1,809 6,337 Other loans 1,207 — 784 784 553 1,033 Total $ 47,289 $ 23,550 $ 17,667 $ 41,217 $ 5,459 $ 48,525
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, 2020 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Other secured by 1-4 family residential properties 13 $ 923 $ 929 Secured by nonfarm, nonresidential properties 2 1,111 1,111 Commercial and industrial loans 4 1,665 1,664 Consumer loans 6 26 26 State and other political subdivision loans 2 3,902 3,872 Total 27 $ 7,627 $ 7,602 Year Ended December 31, 2019 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Secured by 1-4 family residential properties 19 $ 1,742 $ 1,738 Secured by nonfarm, nonresidential properties 1 5,055 5,055 Commercial and industrial loans 8 9,167 9,054 Consumer loans 2 30 30 Total 30 $ 15,994 $ 15,877 Year Ended December 31, 2018 Modifications Classified as TDRs Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Loans secured by real estate: Construction, land development and other land 1 $ 22 $ 22 Secured by 1-4 family residential properties 23 2,102 1,660 Secured by nonfarm, nonresidential properties 2 1,780 1,780 Commercial and industrial loans 23 26,970 25,862 Consumer loans 3 4 4 Total 52 $ 30,878 $ 29,328
Troubled Debt Restructuring Subsequently Defaulted	The table below includes the balances at default for TDRs modified within the last 12 months for which there was a payment default during the periods presented ($ in thousands): Years Ended December 31, 2020 2019 2018 TDRs that Subsequently Defaulted Number of Contracts Recorded Investment Number of Contracts Recorded Investment Number of Contracts Recorded Investment Loans secured by real estate: Construction, land development and other land — $ — — $ — 1 $ 22 Other secured by 1-4 family residential properties 2 78 3 446 5 734 Secured by nonfarm, nonresidential properties 1 139 — — — — Commercial and industrial loans 1 82 7 192 6 15,178 Consumer loans — — 1 27 1 1 Total 4 $ 299 11 $ 665 13 $ 15,935
Troubled Debt Restructuring Related to Loans Held for Investment by Loan Type	The following tables detail LHFI classified as TDRs by loan class at December 31, 2020, 2019 and 2018 ($ in thousands): December 31, 2020 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 12 $ 12 Other secured by 1-4 family residential properties — 3,699 3,699 Secured by nonfarm, nonresidential properties — 3,903 3,903 Commercial and industrial loans 1,500 12,749 14,249 Consumer loans 6 17 23 State and other political subdivision loans — 3,793 3,793 Other commercial loans — 81 81 Total TDRs $ 1,506 $ 24,254 $ 25,760 December 31, 2019 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 15 $ 15 Secured by 1-4 family residential properties 77 3,865 3,942 Secured by nonfarm, nonresidential properties — 5,176 5,176 Commercial and industrial loans 3,319 18,913 22,232 Consumer loans — 21 21 Other loans — 137 137 Total TDRs $ 3,396 $ 28,127 $ 31,523 December 31, 2018 Accruing Nonaccrual Total Loans secured by real estate: Construction, land development and other land $ — $ 24 $ 24 Secured by 1-4 family residential properties 743 3,125 3,868 Secured by nonfarm, nonresidential properties 1,734 395 2,129 Commercial and industrial loans 9,007 12,620 21,627 Consumer loans — 2 2 Other loans — 540 540 Total TDRs $ 11,484 $ 16,706 $ 28,190
Schedule of Amortized Cost Basis of Collateral-Dependent Loans	The following table presents the amortized cost basis of collateral-dependent loans by class of loans and collateral type as of December 31, 2020 ($ in thousands): December 31, 2020 Real Estate Equipment and Machinery Inventory and Receivables Vehicles Miscellaneous Total Loans secured by real estate: Construction, land development and other land $ 5,756 $ — $ — $ — $ — $ 5,756 Other secured by 1-4 family residential properties 454 — — — — 454 Secured by nonfarm, nonresidential properties 12,037 — — — — 12,037 Other real estate secured 60 — — — — 60 Other loans secured by real estate: Other construction — — — — — — Secured by 1-4 family residential properties 1,441 — — — — 1,441 Commercial and industrial loans 86 425 4,899 135 8,531 14,076 Consumer loans — — — — — — State and other political subdivision loans 3,970 — — — — 3,970 Other commercial loans 606 — 1,958 — 3,051 5,615 Total $ 24,410 $ 425 $ 6,857 $ 135 $ 11,582 $ 43,409
Carrying Amount of Loans by Credit Quality Indicator	The tables below present the amortized cost basis of loans by credit quality indicator and class of loans based on the most recent analysis performed ($ in thousands): Term Loans by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Total As of December 31, 2020 Commercial LHFI Loans secured by real estate: Construction, land development and other land: Pass - RR 1 through RR 6 $ 287,218 $ 62,078 $ 26,401 $ 4,487 $ 3,274 $ 3,564 $ 28,548 $ 415,570 Special Mention - RR 7 — — — — — — — — Substandard - RR 8 5,419 4,363 1,226 12 494 22 101 11,637 Doubtful - RR 9 — — — — — 42 — 42 Total 292,637 66,441 27,627 4,499 3,768 3,628 28,649 427,249 Other secured by 1-4 family residential properties: Pass - RR 1 through RR 6 $ 35,139 $ 19,596 $ 15,399 $ 9,605 $ 10,273 $ 4,786 $ 8,486 $ 103,284 Special Mention - RR 7 255 — 50 — — — — 305 Substandard - RR 8 1,155 8 914 341 302 337 3,950 7,007 Doubtful - RR 9 29 — — — — — — 29 Total 36,578 19,604 16,363 9,946 10,575 5,123 12,436 110,625 Secured by nonfarm, nonresidential properties: Pass - RR 1 through RR 6 $ 697,439 $ 496,476 $ 442,264 $ 293,072 $ 254,747 $ 251,219 $ 96,098 $ 2,531,315 Special Mention - RR 7 13,452 6,139 2,956 4,466 4,957 20,545 — 52,515 Substandard - RR 8 19,119 20,572 4,516 12,956 38,956 25,438 2,779 124,336 Doubtful - RR 9 52 163 — — 217 306 — 738 Total 730,062 523,350 449,736 310,494 298,877 297,508 98,877 2,708,904 Other real estate secured: Pass - RR 1 through RR 6 $ 146,803 $ 376,765 $ 347,472 $ 48,626 $ 89,824 $ 23,680 $ 12,116 $ 1,045,286 Special Mention - RR 7 — — — — — 841 — 841 Substandard - RR 8 18,649 14 18 — 556 122 — 19,359 Doubtful - RR 9 — — — — — — — — Total 165,452 376,779 347,490 48,626 90,380 24,643 12,116 1,065,486 Term Loans by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Total As of December 31, 2020 Commercial LHFI Other loans secured by real estate: Other construction Pass - RR 1 through RR 6 $ 262,544 $ 425,936 $ 81,476 $ 14,074 $ 2,464 $ — $ 7,735 $ 794,229 Special Mention - RR 7 — — — — — — — — Substandard - RR 8 754 — — — — — — 754 Doubtful - RR 9 — — — — — — — — Total 263,298 425,936 81,476 14,074 2,464 — 7,735 794,983 Commercial and industrial loans: Pass - RR 1 through RR 6 $ 444,304 $ 165,163 $ 77,611 $ 77,985 $ 59,131 $ 43,214 $ 372,486 $ 1,239,894 Special Mention - RR 7 677 45 — — — — 240 962 Substandard - RR 8 12,090 1,814 9,737 3,735 2,160 5,024 33,380 67,940 Doubtful - RR 9 151 95 — — 32 4 — 282 Total 457,222 167,117 87,348 81,720 61,323 48,242 406,106 1,309,078 State and other political subdivision loans: Pass - RR 1 through RR 6 $ 250,363 $ 79,595 $ 41,334 $ 113,817 $ 132,634 $ 372,831 $ 1,446 $ 992,020 Special Mention - RR 7 — — — — — 4,018 — 4,018 Substandard - RR 8 — — — 247 — 4,491 — 4,738 Doubtful - RR 9 — — — — — — — — Total 250,363 79,595 41,334 114,064 132,634 381,340 1,446 1,000,776 Other commercial loans: Pass - RR 1 through RR 6 $ 101,230 $ 70,990 $ 20,769 $ 9,723 $ 33,481 $ 30,715 $ 225,533 $ 492,441 Special Mention - RR 7 7,500 — — — — — 11,333 18,833 Substandard - RR 8 381 2,099 683 6 707 — 9,948 13,824 Doubtful - RR 9 2 — — — — 23 — 25 Total 109,113 73,089 21,452 9,729 34,188 30,738 246,814 525,123 Total commercial LHFI $ 2,304,725 $ 1,731,911 $ 1,072,826 $ 593,152 $ 634,209 $ 791,222 $ 814,179 $ 7,942,224 Term Loans by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Total As of December 31, 2020 Consumer LHFI Loans secured by real estate: Construction, land development and other land: Current $ 47,336 $ 24,174 $ 8,496 $ 2,036 $ 1,447 $ 2,868 $ — $ 86,357 Past due 30-89 days — 318 20 — 1 12 — 351 Past due 90 days or more — — — — — — — — Nonaccrual — — — — — 99 — 99 Total 47,336 24,492 8,516 2,036 1,448 2,979 — 86,807 Other secured by 1-4 family residential properties: Current $ 20,864 $ 10,253 $ 12,037 $ 4,177 $ 2,082 $ 11,124 $ 348,830 $ 409,367 Past due 30-89 days 93 12 — 13 — 133 1,058 1,309 Past due 90 days or more — — — — — 30 22 52 Nonaccrual 6 44 121 428 — 382 2,398 3,379 Total 20,963 10,309 12,158 4,618 2,082 11,669 352,308 414,107 Secured by nonfarm, nonresidential properties: Current $ 109 $ — $ — $ 4 $ — $ 9 $ — $ 122 Past due 30-89 days — — — — — — — — Past due 90 days or more — — — — — — — — Nonaccrual — — — — — — — — Total 109 — — 4 — 9 — 122 Other real estate secured: Current $ 107 $ — $ 38 $ 37 $ 96 $ 200 $ — $ 478 Past due 30-89 days — — — — — — — — Past due 90 days or more — — — — — — — — Nonaccrual — — — — — — — — Total 107 — 38 37 96 200 — 478 Term Loans by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Total As of December 31, 2020 Consumer LHFI Other loans secured by real estate: Secured by 1-4 family residential properties Current $ 289,521 $ 214,056 $ 173,324 $ 92,564 $ 109,031 $ 321,250 $ — $ 1,199,746 Past due 30-89 days 499 93 753 366 1,080 799 — 3,590 Past due 90 days or more 159 214 208 127 — 549 — 1,257 Nonaccrual 283 711 2,024 682 239 7,868 — 11,807 Total 290,462 215,074 176,309 93,739 110,350 330,466 — 1,216,400 Consumer loans: Current $ 65,370 $ 25,303 $ 13,140 $ 3,893 $ 1,257 $ 345 $ 53,669 $ 162,977 Past due 30-89 days 524 158 67 19 7 3 305 1,083 Past due 90 days or more 77 — 4 — — — 159 240 Nonaccrual 12 4 55 13 2 — — 86 Total 65,983 25,465 13,266 3,925 1,266 348 54,133 164,386 Total consumer LHFI $ 424,960 $ 275,340 $ 210,287 $ 104,359 $ 115,242 $ 345,671 $ 406,441 $ 1,882,300 Total LHFI $ 2,729,685 $ 2,007,251 $ 1,283,113 $ 697,511 $ 749,451 $ 1,136,893 $ 1,220,620 $ 9,824,524 The tables below present LHFI by loan class and credit quality indicator at December 31, 2019 ($ in thousands): December 31, 2019 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 $ 1,075,146 $ — $ 15,726 $ 42 $ 1,090,914 Secured by 1-4 family residential properties 116,592 45 6,355 41 123,033 Secured by nonfarm, nonresidential properties 2,430,761 — 44,001 328 2,475,090 Other real estate secured 721,238 — 2,547 — 723,785 Commercial and industrial loans 1,407,837 909 68,262 888 1,477,896 Consumer loans — — — — — State and other political subdivision loans 957,948 4,650 5,346 — 967,944 Other loans 469,095 3,445 16,926 30 489,496 Total $ 7,178,617 $ 9,049 $ 159,163 $ 1,329 $ 7,348,158 Consumer LHFI Past Due Past Due Current 30-89 Days 90 Nonaccrual Subtotal Total LHFI Loans secured by real estate: Construction, land development and other land $ 71,413 $ 332 $ — $ 132 $ 71,877 $ 1,162,791 Secured by 1-4 family residential properties 1,710,930 5,922 211 15,817 1,732,880 1,855,913 Secured by nonfarm, nonresidential properties 155 — — — 155 2,475,245 Other real estate secured 695 — — — 695 724,480 Commercial and industrial loans — — — — — 1,477,896 Consumer loans 172,649 2,588 393 108 175,738 175,738 State and other political subdivision loans — — — — — 967,944 Other loans 6,125 — — — 6,125 495,621 Total $ 1,961,967 $ 8,842 $ 604 $ 16,057 $ 1,987,470 $ 9,335,628
Summary of Trustmark's Portfolio Segments, Loan Classes, Loan Pools and the ACL Methodology and Loss Drivers	The following table provides a description of each of Trustmark’s portfolio segments, loan classes, loan pools and the ACL methodology and loss drivers: Portfolio Segment Loan Class Loan Pool Methodology Loss Drivers Loans secured by real estate Construction, land development and other land 1-4 family residential construction DCF Prime Rate, National GDP Lots and development DCF Prime Rate, Southern Unemployment Unimproved land DCF Prime Rate, Southern Unemployment All other consumer DCF Prime Rate, Southern Unemployment Other secured by 1-4 family residential properties Consumer 1-4 family - 1st liens DCF Prime Rate, Southern Unemployment All other consumer DCF Prime Rate, Southern Unemployment Nonresidential owner-occupied DCF Southern Unemployment, National GDP Secured by nonfarm, nonresidential properties Nonowner-occupied - hotel/motel DCF Southern Vacancy Rate, Southern Unemployment Nonowner-occupied - office DCF Southern Vacancy Rate, Southern Unemployment Nonowner-occupied- Retail DCF Southern Vacancy Rate, Southern Unemployment Nonowner-occupied - senior living/nursing homes DCF Southern Vacancy Rate, Southern Unemployment Nonowner-occupied - all other DCF Southern Vacancy Rate, Southern Unemployment Nonresidential owner-occupied DCF Southern Unemployment, National GDP Other real estate secured Nonresidential nonowner -occupied - apartments DCF Southern Vacancy Rate, Southern Unemployment Nonresidential owner-occupied DCF Southern Unemployment, National GDP Nonowner-occupied - all other DCF Southern Vacancy Rate, Southern Unemployment Other loans secured by real estate Other construction Other construction WARM Prime Rate, National Unemployment Secured by 1-4 family residential properties Trustmark mortgage WARM Southern Unemployment Commercial and industrial loans Commercial and industrial loans Commercial and industrial - non-working capital DCF Trustmark historical data Commercial and industrial - working capital DCF Trustmark historical data Credit cards WARM Trustmark call report data Consumer loans Consumer loans Credit cards WARM Trustmark call report data Overdrafts Loss Rate Trustmark historical data All other consumer DCF Prime Rate, Southern Unemployment State and other political subdivision loans State and other political subdivision loans Obligations of state and political subdivisions DCF Moody's Bond Default Study Other commercial loans Other commercial loans Other loans DCF Prime Rate, Southern Unemployment Commercial and industrial - non-working capital DCF Trustmark historical data Commercial and industrial - working capital DCF Trustmark historical data
Change in Allowance for Loan Losses	The following table disaggregates the ACL and the amortized cost basis of the loans by the measurement methodology used at December 31, 2020 ($ in thousands): Year Ended December 31, 2020 ACL LHFI Individually Evaluated for Credit Loss Collectively Evaluated for Credit Loss Total ACL Individually Evaluated for Credit Loss Collectively Evaluated for Credit Loss Total LHFI Loans secured by real estate: Construction, land development and other land $ — $ 6,854 $ 6,854 $ 5,756 508,300 $ 514,056 Other secured by 1-4 family residential properties — 9,928 9,928 454 524,278 524,732 Secured by nonfarm, nonresidential properties — 48,523 48,523 12,037 2,696,989 2,709,026 Other real estate secured — 7,382 7,382 60 1,065,904 1,065,964 Other loans secured by real estate: Other construction — 8,158 8,158 — 794,983 794,983 Secured by 1-4 family residential properties — 5,143 5,143 1,441 1,214,959 1,216,400 Commercial and industrial loans 579 14,272 14,851 14,076 1,295,002 1,309,078 Consumer loans — 5,838 5,838 — 164,386 164,386 State and other political subdivision loans 1,700 1,490 3,190 3,970 996,806 1,000,776 Other commercial loans 2,100 5,339 7,439 5,615 519,508 525,123 Total $ 4,379 $ 112,927 $ 117,306 $ 43,409 $ 9,781,115 $ 9,824,524 The following table disaggregates the allowance for loan losses and LHFI balances by the impairment evaluation methodology used at December 31, 2019 ($ in thousands): December 31, 2019 Allowance for Loan Losses LHFI Individually Evaluated Collectively Evaluated Total Individually Evaluated Collectively Evaluated Total Loans secured by real estate: Construction, land development and other land $ — $ 8,260 $ 8,260 $ 626 $ 1,162,165 $ 1,162,791 Secured by 1-4 family residential properties 35 8,897 8,932 5,464 1,850,449 1,855,913 Secured by nonfarm, nonresidential properties 2,355 23,803 26,158 6,717 2,468,528 2,475,245 Other real estate secured — 4,024 4,024 68 724,412 724,480 Commercial and industrial loans 707 25,285 25,992 23,458 1,454,438 1,477,896 Consumer loans — 3,379 3,379 21 175,717 175,738 State and other political subdivision loans 1,809 420 2,229 4,079 963,865 967,944 Other loans 553 4,750 5,303 784 494,837 495,621 Total $ 5,459 $ 78,818 $ 84,277 $ 41,217 $ 9,294,411 $ 9,335,628 Changes in the ACL were as follows for the periods presented ($ in thousands): Years Ended December 31, 2020 2019 2018 Balance at beginning of period $ 84,277 $ 79,290 $ 76,733 FASB ASU 2016-13 adoption adjustments: LHFI (3,039 ) — — Allowance for loan losses, acquired loans transfer 815 — — Acquired loans ACL adjustment 1,007 — — Transfers (1) — — 1,554 Loans charged-off (11,475 ) (14,481 ) (29,489 ) Recoveries 9,608 8,671 12,499 Net (charge-offs) recoveries (1,867 ) (5,810 ) (16,990 ) PCL 36,113 10,797 17,993 Balance at end of period $ 117,306 $ 84,277 $ 79,290 (1) The allowance for loan losses balance related to the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions, which were transferred from acquired impaired loans to LHFI during 2018. The following table details changes in the ACL by loan class for the year ended December 31, 2020 ($ in thousands): 2020 Balance FASB ASU 2016-13 Balance January 1, Adoption Adjustment Charge-offs Recoveries PCL December 31, Loans secured by real estate: Construction, land development and other land $ 6,371 $ (188 ) $ (12 ) $ 716 $ (33 ) $ 6,854 Other secured by 1-4 family residential properties 5,888 4,188 (117 ) 378 (409 ) 9,928 Secured by nonfarm, nonresidential properties 26,158 (8,179 ) (3,777 ) 546 33,775 48,523 Other real estate secured 4,024 (765 ) (8 ) 68 4,063 7,382 Other loans secured by real estate: Other construction 1,889 3,202 — 208 2,859 8,158 Secured by 1-4 family residential properties 3,044 2,891 (43 ) 203 (952 ) 5,143 Commercial and industrial loans 25,992 (8,964 ) (1,557 ) 1,736 (2,356 ) 14,851 Consumer loans 3,379 2,059 (2,039 ) 1,824 615 5,838 State and other political subdivision loans 2,229 2,455 — — (1,494 ) 3,190 Other commercial loans 5,303 2,084 (3,922 ) 3,929 45 7,439 Total $ 84,277 $ (1,217 ) $ (11,475 ) $ 9,608 $ 36,113 $ 117,306 The following table details changes in the allowance for loan losses, LHFI by loan class for the year ended December 31, 2019 ($ in thousands): 2019 Balance Provision for Balance January 1, Charge-offs Recoveries Loan Losses December 31, Loans secured by real estate: Construction, land development and other land $ 7,390 $ (40 ) $ 894 $ 16 $ 8,260 Secured by 1-4 family residential properties 8,641 (531 ) 666 156 8,932 Secured by nonfarm, nonresidential properties 22,376 (322 ) 472 3,632 26,158 Other real estate secured 3,450 — 29 545 4,024 Commercial and industrial loans 27,359 (5,344 ) 1,257 2,720 25,992 Consumer loans 2,890 (2,278 ) 1,829 938 3,379 State and other political subdivision loans 990 — — 1,239 2,229 Other loans 6,194 (5,966 ) 3,524 1,551 5,303 Total allowance for loan losses, LHFI $ 79,290 $ (14,481 ) $ 8,671 $ 10,797 $ 84,277

Acquired Loans (Tables)

Acquired Loans (Tables)	12 Months Ended
	Dec. 31, 2020
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities [Abstract]
Schedule of Acquired Loans	At December 31, 2019, acquired loans consisted of the following ($ in thousands): December 31, 2019 Loans secured by real estate: Construction, land development and other land $ 4,771 Secured by 1-4 family residential properties 17,525 Secured by nonfarm, nonresidential properties 38,206 Other real estate secured 3,946 Commercial and industrial loans 5,035 Consumer loans 520 Other loans 2,598 Acquired loans 72,601 Less allowance for loan losses, acquired loans 815 Net acquired loans $ 71,786
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, 2019 $ 102,890 $ 2,811 Transfers (2) — (2,926 ) Accretion to interest income 5,532 115 Payments received, net (37,230 ) — Other (3) 178 — Change in allowance for loan losses, acquired loans 416 — Carrying value, net at December 31, 2019 71,786 — FASB ASU 2016-13 adoption adjustment (71,786 ) — Carrying value, net at December 31, 2020 $ — $ — (1) “Acquired Not ASC 310-30” loans consist of loans that are not in scope for FASB ASC Subtopic 310-30. (2) “Acquired Not ASC 310-30” loans transferred to LHFI due to the discount on these loans being fully amortized. ( 3 ) Includes miscellaneous timing adjustments as well as acquired loan terminations through foreclosure, charge-off and other terminations.
Changes in Accretable Yield of Acquired Loans	The following table presents changes in the accretable yield for the periods presented ($ in thousands): Years Ended December 31, 2020 2019 2018 Accretable yield at beginning of period $ (14,816 ) $ (17,722 ) $ (31,426 ) FASB ASU 2016-13 adoption adjustment 14,816 — — Accretion to interest income — 5,532 9,514 Disposals, net — 2,072 3,926 Transfers (1) — — 5,874 Reclassification from nonaccretable difference (2) — (4,698 ) (5,610 ) Accretable yield at end of period $ — $ (14,816 ) $ (17,722 ) (1) During 2018, Trustmark transferred the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions from acquired impaired loans to LHFI. ( 2 ) 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 table presents the components of the allowance for loan losses on acquired impaired loans for the periods presented ($ in thousands): Years Ended December 31, 2020 2019 2018 Balance at beginning of period $ 815 $ 1,231 $ 4,079 FASB ASU 2016-13 adoption adjustment (815 ) — — Transfers (1) — — (1,554 ) Net (charge-offs) recoveries — (458 ) (289 ) Provision for loan losses, acquired loans — 42 (1,005 ) Balance at end of period $ — $ 815 $ 1,231 (1) The allowance for loan losses balance related to the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisition s , which were transferred from acquired impaired loans to LHFI during 2018.
Acquired Loans by Loan Class and Credit Quality Indicator	The table below presents the acquired loans by loan class and credit quality indicator at December 31, 2019 ($ in thousands): December 31, 2019 Commercial Loans Pass - Special Mention - Substandard - Doubtful - Categories 1-6 Category 7 Category 8 Category 9 Subtotal Loans secured by real estate: Construction, land development and other land $ 4,022 $ — $ 192 $ — $ 4,214 Secured by 1-4 family residential properties 3,164 42 580 — 3,786 Secured by nonfarm, nonresidential properties 27,848 — 9,972 386 38,206 Other real estate secured 3,878 — 68 — 3,946 Commercial and industrial loans 3,419 — — 1,616 5,035 Consumer loans — — — — — Other loans 2,591 — 7 — 2,598 Total acquired loans $ 44,922 $ 42 $ 10,819 $ 2,002 $ 57,785 Consumer Loans Past Due Past Due Total Current 30-89 Days 90 Days or More Nonaccrual (1) Subtotal Acquired Loans Loans secured by real estate: Construction, land development and other land $ 463 $ 94 $ — $ — $ 557 $ 4,771 Secured by 1-4 family residential properties 12,843 615 281 — 13,739 17,525 Secured by nonfarm, nonresidential properties — — — — — 38,206 Other real estate secured — — — — — 3,946 Commercial and industrial loans — — — — — 5,035 Consumer loans 489 31 — — 520 520 Other loans — — — — — 2,598 Total acquired loans $ 13,795 $ 740 $ 281 $ — $ 14,816 $ 72,601 (1) Acquired loans not accounted for under FASB ASC Subtopic 310-30 .
Aging Analysis of Past Due and Nonaccrual Acquired Loans	The following table provides an aging analysis of contractually past due and nonaccrual acquired loans at December 31, 2019 ($ in thousands): December 31, 2019 Past Due 30-59 Days 60-89 Days 90 Days or More (1) Total Nonaccrual (2) Current Loans Total Acquired Loans Loans secured by real estate: Construction, land development and other land $ 94 $ — $ 38 $ 132 $ — $ 4,639 $ 4,771 Secured by 1-4 family residential properties 696 131 366 1,193 — 16,332 17,525 Secured by nonfarm, nonresidential properties 36 — 851 887 — 37,319 38,206 Other real estate secured 1 — 52 53 — 3,893 3,946 Commercial and industrial loans — — — — — 5,035 5,035 Consumer loans 16 15 — 31 — 489 520 Other loans — — — — — 2,598 2,598 Total acquired loans $ 843 $ 146 $ 1,307 $ 2,296 $ — $ 70,305 $ 72,601 (1) Past due 90 days or more but still accruing interest. (2) Acquired loans not accounted for under FASB ASC Subtopic 310-30.

Premises and Equipment, Net (Ta

Premises and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Premises and Equipment, Net	At December 31, 2020 and 2019, premises and equipment, net consisted of the following ($ in thousands): December 31, 2020 2019 Land $ 52,189 $ 52,454 Buildings and leasehold improvements 216,650 210,362 Furniture and equipment 180,976 174,257 Total cost of premises and equipment 449,815 437,073 Less accumulated depreciation and amortization 263,147 256,608 Premises and equipment, net 186,668 180,465 Finance lease right-of-use assets 7,471 9,326 Assets held for sale 139 — Total premises and equipment, net $ 194,278 $ 189,791

Mortgage Banking (Tables)

Mortgage Banking (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 Balance at beginning of period $ 79,394 $ 95,596 Origination of servicing assets 29,805 16,711 Change in fair value: Due to market changes (26,147 ) (21,078 ) Due to runoff (16,588 ) (11,835 ) Balance at end of period $ 66,464 $ 79,394
Schedule of Mortgage Loans Sold and Serviced for Others	The table below details the mortgage loans sold and serviced for others at December 31, 2020 and 2019 ($ in thousands): December 31, 2020 2019 Federal National Mortgage Association $ 4,629,670 $ 4,411,914 Government National Mortgage Association 2,960,760 2,652,782 Federal Home Loan Mortgage Corporation 50,459 73,134 Other 16,201 19,404 Total mortgage loans sold and serviced for others $ 7,657,090 $ 7,157,234

Goodwill and Identifiable Int_2

Goodwill and Identifiable Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill by segment	The table below illustrates goodwill by segment for the years ended December 31, 2020 and 2019 ($ in thousands): General Banking Insurance Total Balance as of January 1, 2019 $ 334,603 $ 45,024 $ 379,627 Adjustment during 2019 — — — Balance as of December 31, 2019 334,603 45,024 379,627 Adjustment during 2020 — 5,643 5,643 Balance as of December 31, 2020 $ 334,603 $ 50,667 $ 385,270
Schedule of identifiable intangible assets	At December 31, 2020 and 2019, identifiable intangible assets consisted of the following ($ in thousands): December 31, 2020 December 31, 2019 Gross Accumulated Net Carrying Gross Carrying Accumulated Net Carrying Amount Amortization Amount Amount Amortization Amount Core deposit intangibles $ 87,674 $ 84,580 $ 3,094 $ 87,674 $ 82,096 $ 5,578 Insurance intangibles 17,272 13,159 4,113 14,171 12,655 1,516 Banking charters 1,325 1,142 183 1,325 1,076 249 Total $ 106,271 $ 98,881 $ 7,390 $ 103,170 $ 95,827 $ 7,343 The following table illustrates the carrying amounts and remaining weighted-average amortization periods of identifiable intangible assets as of December 31, 2020 ($ in thousands): Remaining Weighted- Average Net Carrying Amortization Amount Period in Core deposit intangibles $ 3,094 3.1 Insurance intangibles 4,113 17.0 Banking charters 183 2.7 Total $ 7,390 10.8

Other Real Estate (Tables)

Other Real Estate (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 2018 Balance at beginning of period $ 29,248 $ 34,668 $ 43,228 Additions 635 8,598 12,115 Disposals (16,446 ) (11,474 ) (19,802 ) Write-downs (1,786 ) (2,544 ) (873 ) Balance at end of period $ 11,651 $ 29,248 $ 34,668 Gains (losses), net on the sale of other real estate included in other real estate expense $ 897 $ (291 ) $ 700
Other Real Estate, By Type of Property	At December 31, 2020 and 2019, other real estate by type of property consisted of the following ($ in thousands): December 31, 2020 2019 Construction, land development and other land properties $ 3,857 $ 11,482 1-4 family residential properties 1,349 3,453 Nonfarm, nonresidential properties 6,445 14,313 Other real estate properties — — Total other real estate $ 11,651 $ 29,248
Other Real Estate, By Geographic Location	At December 31, 2020 and 2019, other real estate by geographic location consisted of the following ($ in thousands): December 31, 2020 2019 Alabama $ 3,271 $ 8,133 Florida — 5,877 Mississippi (1) 8,330 14,919 Tennessee (2) 50 319 Texas — — Total other real estate $ 11,651 $ 29,248 (1) Mississippi includes Central and Southern Mississippi Regions. (2) Tennessee includes Memphis, Tennessee and Northern Mississippi Regions.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Components of Net Lease Cost	The table below details the components of net lease cost for the periods presented ($ in thousands): Year Ended December 31, 2020 2019 Finance leases Amortization of right-of-use assets $ 1,856 $ 2,162 Interest on lease liabilities 254 307 Operating lease cost 5,188 5,183 Short-term lease cost 423 370 Variable lease cost 1,286 1,387 Sublease income (335 ) (331 ) Net lease cost $ 8,672 $ 9,078
Cash Payments Included in Measurement of Lease Liabilities	The table below details the cash payments included in the measurement of lease liabilities during the periods presented ($ in thousands): Year Ended December 31, 2020 2019 Finance leases Operating cash flows included in operating activities $ 254 $ 307 Financing cash flows included in payments under finance lease obligations 1,715 1,964 Operating leases Operating cash flows (fixed payments) included in other operating activities, net 4,988 5,092 Operating cash flows (liability reduction) included in other operating activities, net 3,856 5,404
Balance Sheet Information and Weighted-Average Lease Terms and Discount Rates Related to Leases	The table below details balance sheet information, as well as weighted-average lease terms and discount rates, for the periods presented ($ in thousands): Year Ended December 31, 2020 2019 Finance lease right-of-use assets, net of accumulated depreciation $ 7,471 $ 9,326 Finance lease liabilities 7,805 9,520 Operating lease right-of-use assets 30,901 31,182 Operating lease liabilities 32,290 32,354 Weighted-average lease term Finance leases 8.53 years 8.62 years Operating leases 8.65 years 9.05 years Weighted-average discount rate Finance leases 3.10 % 3.01 % Operating leases 3.41 % 3.51 %
Future Minimum Rental Commitments Under Finance and Operating Leases	At December 31, 2020, future minimum rental commitments under finance and operating leases were as follows ($ in thousands): Finance Leases Operating Leases 2021 $ 1,615 $ 4,714 2022 1,556 4,456 2023 871 4,342 2024 572 4,449 2025 584 4,464 Thereafter 3,868 15,040 Total minimum lease payments 9,066 37,465 Less imputed interest (1,261 ) (5,175 ) Lease liabilities $ 7,805 $ 32,290

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2020
Deposits [Abstract]
Deposits Summary	At December 31, 2020 and 2019, deposits consisted of the following ($ in thousands): December 2020 2019 Noninterest-bearing demand $ 4,349,010 $ 2,891,215 Interest-bearing demand 3,646,246 3,125,914 Savings 4,647,610 3,590,509 Time 1,405,898 1,637,919 Total $ 14,048,764 $ 11,245,557
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, 2020 2019 2018 Interest-bearing demand $ 9,985 $ 35,428 $ 18,479 Savings 13,481 19,462 17,980 Time 14,021 24,281 17,477 Total $ 37,487 $ 79,171 $ 53,936
Maturities of Interest-Bearing Deposits	The maturities of interest-bearing deposits at December 31, 2020, are as follows ($ in thousands): 2021 $ 1,152,489 2022 176,421 2023 46,750 2024 14,330 2025 12,738 Thereafter 3,170 Total time deposits 1,405,898 Interest-bearing deposits with no stated maturity 8,293,856 Total interest-bearing deposits $ 9,699,754

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 and 2019 ($ in thousands): December 31, 2020 2019 Mortgage-backed securities Residential mortgage pass-through securities Issued by FNMA and FHLMC $ 115,357 $ — Other residential mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA 12,696 24,282 Commercial mortgage-backed securities Issued or guaranteed by FNMA, FHLMC or GNMA — 29,290 Total securities sold under repurchase agreements $ 128,053 $ 53,572
Summary of Other Borrowings	At December 31, 2020 and 2019, other borrowings consisted of the following ($ in thousands): December 2020 2019 FHLB advances $ 741 $ 811 Serviced GNMA loans eligible for repurchase 141,160 57,062 Finance lease liabilities 7,805 9,520 Other 18,546 18,003 Total other borrowings $ 168,252 $ 85,396

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 Year Ended December 31, 2019 (1) Year Ended December 31, 2018 (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 $ 32,213 $ — $ 32,213 $ 42,509 $ — $ 42,509 $ 43,614 $ — $ 43,614 Bank card and other fees 27,398 3,594 30,992 27,973 3,706 31,679 26,904 1,897 28,801 Mortgage banking, net — 125,822 125,822 — 29,822 29,822 — 34,674 34,674 Wealth management 254 — 254 379 — 379 296 — 296 Other, net 7,432 978 8,410 9,528 (161 ) 9,367 6,762 (217 ) 6,545 Total noninterest income $ 67,297 $ 130,394 $ 197,691 $ 80,389 $ 33,367 $ 113,756 $ 77,576 $ 36,354 $ 113,930 Wealth Management Segment Service charges on deposit accounts $ 76 $ — $ 76 $ 94 $ — $ 94 $ 88 $ — $ 88 Bank card and other fees 30 — 30 57 — 57 104 — 104 Wealth management 31,371 — 31,371 30,300 — 30,300 30,042 — 30,042 Other, net 107 50 157 306 103 409 69 117 186 Total noninterest income $ 31,584 $ 50 $ 31,634 $ 30,757 $ 103 $ 30,860 $ 30,303 $ 117 $ 30,420 Insurance Segment Insurance commissions $ 45,176 $ — $ 45,176 $ 42,396 $ — $ 42,396 $ 40,481 $ — $ 40,481 Other, net 92 — 92 33 — 33 5 — 5 Total noninterest income $ 45,268 $ — $ 45,268 $ 42,429 $ — $ 42,429 $ 40,486 $ — $ 40,486 Consolidated Service charges on deposit accounts $ 32,289 $ — $ 32,289 $ 42,603 $ — $ 42,603 $ 43,702 $ — $ 43,702 Bank card and other fees 27,428 3,594 31,022 28,030 3,706 31,736 27,008 1,897 28,905 Mortgage banking, net — 125,822 125,822 — 29,822 29,822 — 34,674 34,674 Insurance commissions 45,176 — 45,176 42,396 — 42,396 40,481 — 40,481 Wealth management 31,625 — 31,625 30,679 — 30,679 30,338 — 30,338 Other, net 7,631 1,028 8,659 9,867 (58 ) 9,809 6,836 (100 ) 6,736 Total noninterest income $ 144,149 $ 130,444 $ 274,593 $ 153,575 $ 33,470 $ 187,045 $ 148,365 $ 36,471 $ 184,836 (1) During the first quarter of 2020, Trustmark revised the composition of its operating segments by moving the Retail Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes. The prior period amounts presented include reclassifications to conform to the current period presentation. (2) 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, 2020
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, 2020 2019 2018 Current Federal $ 40,118 $ 20,068 $ 4,532 State 9,439 7,145 5,997 Deferred Federal (15,840 ) (3,104 ) 9,392 State (3,960 ) (776 ) 2,348 Income tax provision $ 29,757 $ 23,333 $ 22,269
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, 2020 2019 2018 Income tax computed at statutory tax rate $ 39,854 $ 36,497 $ 36,089 Tax exempt interest (4,284 ) (4,951 ) (4,533 ) Nondeductible interest expense 247 564 416 State income taxes, net 7,457 5,645 4,738 Income tax credits, net (9,375 ) (13,473 ) (15,404 ) Death benefit gains (91 ) (123 ) (268 ) Other (4,051 ) (826 ) 1,231 Income tax provision $ 29,757 $ 23,333 $ 22,269
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, 2020 and 2019, which are included in other assets on the accompanying consolidated balance sheets ($ in thousands): December 31, 2020 2019 Deferred tax assets: Loan purchase accounting $ 293 $ 845 Other real estate 2,049 5,845 Accumulated credit losses 39,073 21,774 Deferred compensation 17,465 16,498 Finance and operating lease liabilities 10,024 10,469 Realized built-in losses 10,681 11,431 Securities 2,233 3,028 Pension and other postretirement benefit plans 6,128 5,194 Interest on nonaccrual loans 1,034 942 Loans held for sale 2,754 481 Stock-based compensation 2,749 2,527 Loan fees 3,401 — Other 10,294 8,309 Gross deferred tax asset 108,178 87,343 Deferred tax liabilities: Goodwill and other identifiable intangibles 15,136 15,336 Premises and equipment 11,479 11,913 Finance and operating lease right-of-use assets 9,593 10,127 Mortgage servicing rights 7,108 11,002 Securities 9,712 2,115 Other 4,537 5,192 Gross deferred tax liability 57,565 55,685 Net deferred tax asset $ 50,613 $ 31,658
Changes in Unrecognized Tax Benefits	The following table provides a summary of the changes during the 2020 calendar year in the amount of unrecognized tax benefits that are included in other liabilities in the consolidated balance sheet ($ in thousands): December 31, 2020 2019 2018 Balance at beginning of period $ 1,524 $ 1,249 $ 1,105 Change due to tax positions taken during the current year 353 279 282 Change due to tax positions taken during a prior year 79 134 56 Change due to the lapse of applicable statute of limitations during the current year (175 ) (138 ) (194 ) Change due to settlements with taxing authorities during the current year — — — Balance at end of period $ 1,781 $ 1,524 $ 1,249 Accrued interest, net of federal benefit $ 330 $ 271 $ 212 Unrecognized tax benefits that would impact the effective tax rate, if recognized $ 1,420 $ 1,218 $ 988

Defined Benefit and Other Pos_2

Defined Benefit and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2020
Trustmark Capital Accumulation Plan [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan Benefit Obligation, Plan Assets and Funded Status of the Plan	The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for the Continuing Plan for the periods presented ($ in thousands): December 31, 2020 2019 Change in benefit obligation: Benefit obligation, beginning of year $ 9,060 $ 9,179 Service cost 254 211 Interest cost 241 361 Actuarial (gain) loss 876 875 Benefits paid (884 ) (1,566 ) Benefit obligation, end of year $ 9,547 $ 9,060 Change in plan assets: Fair value of plan assets, beginning of year $ 3,443 $ 3,954 Actual return on plan assets (87 ) 668 Employer contributions 401 387 Benefit payments (884 ) (1,566 ) Fair value of plan assets, end of year $ 2,873 $ 3,443 Funded status at end of year - net liability $ (6,674 ) $ (5,617 ) Amounts recognized in accumulated other comprehensive loss: Net loss - amount recognized $ 2,564 $ 1,893
Net Periodic Benefit Cost	Years Ended December 31, 2020 2019 2018 Net periodic benefit cost: Service cost $ 254 $ 211 $ 277 Interest cost 241 361 332 Expected return on plan assets (154 ) (202 ) (227 ) Recognized net loss due to lump sum settlements 119 312 161 Recognized net actuarial loss 326 373 571 Net periodic benefit cost $ 786 $ 1,055 $ 1,114 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) $ 671 $ (277 ) $ (1,017 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ 1,457 $ 778 $ 97 Weighted-average assumptions as of end of year: Discount rate for benefit obligation 1.95 % 2.84 % 3.97 % Discount rate for net periodic benefit cost 2.84 % 3.97 % 3.32 % Expected long-term return on plan assets 5.00 % 5.00 % 5.00 %
Weighted-Average Asset Allocation	The weighted-average asset allocations by asset category are presented below for the Continuing Plan at December 31, 2020 and 2019. December 31, 2020 2019 Money market fund 5.0 % 2.0 % Exchange traded funds: Equity securities 43.0 % 46.0 % Fixed income 41.0 % 41.0 % International 11.0 % 11.0 % Total 100.0 % 100.0 %
Plan Assets Measured at Fair Value	The following table sets forth by level, within the fair value hierarchy, the Continuing Plan’s assets measured at fair value at December 31, 2020 and 2019 ($ in thousands): December 31, 2020 Total Level 1 Level 2 Level 3 Money market fund $ 131 $ 131 $ — $ — Exchange traded funds: Equity securities 1,242 1,242 — — Fixed income 1,182 1,182 — — International 318 318 — — Total assets at fair value $ 2,873 $ 2,873 $ — $ — December 31, 2019 Total Level 1 Level 2 Level 3 Money market fund $ 51 $ 51 $ — $ — Exchange traded funds: Equity securities 1,592 1,592 — — Fixed income 1,417 1,417 — — International 383 383 — — Total assets at fair value $ 3,443 $ 3,443 $ — $ —
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 2021 $ 1,437 2022 997 2023 1,466 2024 1,162 2025 569 2026 - 2030 2,511
Supplemental Retirement Plan [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan Benefit Obligation, Plan Assets and Funded Status of the Plan	The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for Trustmark’s nonqualified supplemental retirement plans for the periods presented ($ in thousands): December 31, 2020 2019 Change in benefit obligation: Benefit obligation, beginning of year $ 57,482 $ 53,257 Service cost 77 109 Interest cost 1,576 2,044 Actuarial (gain) loss 4,168 5,498 Benefits paid (3,657 ) (3,426 ) Benefit obligation, end of year $ 59,646 $ 57,482 Change in plan assets: Fair value of plan assets, beginning of year $ — $ — Employer contributions 3,657 3,426 Benefit payments (3,657 ) (3,426 ) Fair value of plan assets, end of year $ — $ — Funded status at end of year - net liability $ (59,646 ) $ (57,482 ) Amounts recognized in accumulated other comprehensive loss: Net loss $ 21,486 $ 18,275 Prior service cost 459 609 Amounts recognized $ 21,945 $ 18,884
Net Periodic Benefit Cost	Years Ended December 31, 2020 2019 2018 Net periodic benefit cost: Service cost $ 77 $ 109 $ 116 Interest cost 1,576 2,044 1,865 Amortization of prior service cost 150 250 250 Recognized net actuarial loss 957 627 884 Net periodic benefit cost $ 2,760 $ 3,030 $ 3,115 Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes: Net (gain) loss $ 3,211 $ 4,872 $ (4,111 ) Amortization of prior service cost (150 ) (250 ) (250 ) Total recognized in other comprehensive income (loss) $ 3,061 $ 4,622 $ (4,361 ) Total recognized in net periodic benefit cost and other comprehensive income (loss) $ 5,821 $ 7,652 $ (1,246 ) Weighted-average assumptions as of end of year: Discount rate for benefit obligation 1.95 % 2.84 % 3.97 % Discount rate for net periodic benefit cost 2.84 % 3.97 % 3.32 %
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 2021 $ 3,893 2022 4,168 2023 4,033 2024 4,106 2025 3,774 2026 - 2030 17,296

Stock and Incentive Compensat_2

Stock and Incentive Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 Recognized Compensation Expense Unrecognized Weighted Average for Years Ended December 31, Compensation Life of 2020 2019 2018 Expense Compensation Expense Performance awards $ 815 $ 1,524 $ 861 $ 1,836 1.57 Time-based awards 4,382 3,263 3,009 2,868 1.54 Total $ 5,197 $ 4,787 $ 3,870 $ 4,704
Performance Based Award [Member]
Summary of Stock Plan Activity	The following table summarizes Trustmark’s performance award activity for the periods presented: Years Ended December 31, 2020 2019 2018 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 149,914 $ 32.88 177,695 $ 27.10 213,516 $ 25.37 Granted 53,450 31.98 50,862 33.44 51,174 31.88 Released from restriction (36,357 ) 33.31 (61,347 ) 20.18 (55,351 ) 25.32 Forfeited (21,965 ) 32.97 (17,296 ) 20.18 (31,644 ) 26.26 Nonvested shares, end of year 145,042 $ 32.43 149,914 $ 32.88 177,695 $ 27.10
Time-based Awards [Member]
Summary of Stock Plan Activity	The following table summarizes Trustmark’s time-based award activity for the periods presented: Years Ended December 31, 2020 2019 2018 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 300,006 $ 33.04 321,870 $ 28.48 320,357 $ 25.40 Granted 123,810 31.52 113,673 33.42 118,325 31.96 Released from restriction (110,537 ) 33.58 (124,598 ) 21.64 (107,180 ) 23.02 Forfeited (11,660 ) 32.47 (10,939 ) 32.73 (9,632 ) 29.30 Nonvested shares, end of year 301,619 $ 32.24 300,006 $ 33.04 321,870 $ 28.48

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Summary of Changes in ACL on Off-balance Sheet Credit Exposures	Changes in the ACL on off-balance sheet credit exposures were as follows for the period presented ($ in thousands): Year Ended December 31, 2020 Balance at beginning of period $ — FASB ASU 2016-13 adoption adjustment 29,638 Credit loss expense related to off-balance sheet credit exposures 8,934 Balance at end of period $ 38,572

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 and 2019 ($ in thousands): Actual Regulatory Capital Minimum To Be Well Amount Ratio Requirement Capitalized At December 31, 2020: Common Equity Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,395,844 11.62 % 7.000 % n/a Trustmark National Bank 1,412,015 11.75 % 7.000 % 6.50 % Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,455,844 12.11 % 8.500 % n/a Trustmark National Bank 1,412,015 11.75 % 8.500 % 8.00 % Total Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,696,794 14.12 % 10.500 % n/a Trustmark National Bank 1,530,044 12.73 % 10.500 % 10.00 % Tier 1 Leverage (to Average Assets) Trustmark Corporation $ 1,455,844 9.33 % 4.00 % n/a Trustmark National Bank 1,412,015 9.07 % 4.00 % 5.00 % At December 31, 2019: Common Equity Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,312,668 11.93 % 7.000 % n/a Trustmark National Bank 1,352,893 12.30 % 7.000 % 6.50 % Tier 1 Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,372,668 12.48 % 8.500 % n/a Trustmark National Bank 1,352,893 12.30 % 8.500 % 8.00 % Total Capital (to Risk Weighted Assets) Trustmark Corporation $ 1,457,760 13.25 % 10.500 % n/a Trustmark National Bank 1,437,985 13.07 % 10.500 % 10.00 % Tier 1 Leverage (to Average Assets) Trustmark Corporation $ 1,372,668 10.48 % 4.00 % n/a Trustmark National Bank 1,352,893 10.35 % 4.00 % 5.00 %
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, 2020 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ 30,622 $ (7,657 ) $ 22,965 Change in net unrealized holding loss on securities transferred to held to maturity 3,177 (794 ) 2,383 Total securities available for sale and transferred securities 33,799 (8,451 ) 25,348 Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans (5,128 ) 1,282 (3,846 ) Reclassification adjustments for changes realized in net income: Net change in prior service costs 150 (38 ) 112 Recognized net loss due to lump sum settlements 119 (30 ) 89 Change in net actuarial loss 1,128 (282 ) 846 Total pension and other postretirement benefit plans (3,731 ) 932 (2,799 ) Total other comprehensive income (loss) $ 30,068 $ (7,519 ) $ 22,549 Year Ended December 31, 2019 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ 44,136 $ (11,033 ) $ 33,103 Change in net unrealized holding loss on securities transferred to held to maturity 3,605 (901 ) 2,704 Total securities available for sale and transferred securities 47,741 (11,934 ) 35,807 Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans (5,703 ) 1,425 (4,278 ) Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (63 ) 187 Recognized net loss due to lump sum settlements 312 (77 ) 235 Change in net actuarial loss 796 (199 ) 597 Total pension and other postretirement benefit plans (4,345 ) 1,086 (3,259 ) Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives (145 ) 36 (109 ) Reclassification adjustment for (gain) loss realized in net income (479 ) 119 (360 ) Total cash flow hedge derivatives (624 ) 155 (469 ) Total other comprehensive income (loss) $ 42,772 $ (10,693 ) $ 32,079 Year Ended December 31, 2018 Securities available for sale and transferred securities: Net unrealized holding gains (losses) arising during the period $ (19,221 ) $ 4,805 $ (14,416 ) Change in net unrealized holding loss on securities transferred to held to maturity 3,761 (940 ) 2,821 Total securities available for sale and transferred securities (15,460 ) 3,865 (11,595 ) Pension and other postretirement benefit plans: Change in the actuarial loss of pension and other postretirement benefit plans 3,742 (936 ) 2,806 Reclassification adjustments for changes realized in net income: Net change in prior service costs 250 (63 ) 187 Recognized net loss due to lump sum settlements 161 (39 ) 122 Change in net actuarial loss 1,225 (306 ) 919 Total pension and other postretirement benefit plans 5,378 (1,344 ) 4,034 Cash flow hedge derivatives: Change in accumulated gain (loss) on effective cash flow hedge derivatives 497 (124 ) 373 Reclassification adjustment for (gain) loss realized in net income (322 ) 80 (242 ) Total cash flow hedge derivatives 175 (44 ) 131 Total other comprehensive income (loss) $ (9,907 ) $ 2,477 $ (7,430 )
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, 2018 $ (26,535 ) $ (13,468 ) $ 278 $ (39,725 ) Other comprehensive income (loss) before reclassification (11,595 ) 2,806 373 (8,416 ) Amounts reclassified from accumulated other comprehensive loss — 1,228 (242 ) 986 Net other comprehensive income (loss) (11,595 ) 4,034 131 (7,430 ) Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act (5,694 ) (2,890 ) 60 (8,524 ) Balance, December 31, 2018 (43,824 ) (12,324 ) 469 (55,679 ) Other comprehensive income (loss) before reclassification 35,807 (4,278 ) (109 ) 31,420 Amounts reclassified from accumulated other comprehensive loss — 1,019 (360 ) 659 Net other comprehensive income (loss) 35,807 (3,259 ) (469 ) 32,079 Balance, December 31, 2019 (8,017 ) (15,583 ) — (23,600 ) Other comprehensive income (loss) before reclassification 25,348 (3,846 ) — 21,502 Amounts reclassified from accumulated other comprehensive loss — 1,047 — 1,047 Net other comprehensive income (loss) 25,348 (2,799 ) — 22,549 Balance, December 31, 2020 $ 17,331 $ (18,382 ) $ — $ (1,051 )

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 and 2019, 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, 2020 and 2019. December 31, 2020 Total Level 1 Level 2 Level 3 U.S. Government agency obligations $ 18,041 $ — $ 18,041 $ — Obligations of states and political subdivisions 5,835 — 5,835 — Mortgage-backed securities 1,967,939 — 1,967,939 — Securities available for sale 1,991,815 — 1,991,815 — Loans held for sale 446,951 — 446,951 — Mortgage servicing rights 66,464 — — 66,464 Other assets - derivatives 47,768 145 38,063 9,560 Other liabilities - derivatives 5,324 666 4,658 — December 31, 2019 Total Level 1 Level 2 Level 3 U.S. Government agency obligations $ 22,327 $ — $ 22,327 $ — Obligations of states and political subdivisions 25,465 — 25,465 — Mortgage-backed securities 1,554,612 — 1,554,612 — Securities available for sale 1,602,404 — 1,602,404 — Loans held for sale 226,347 — 226,347 — Mortgage servicing rights 79,394 — — 79,394 Other assets - derivatives 17,956 244 16,273 1,439 Other liabilities - derivatives 6,063 4,414 1,649 —
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, 2020 and 2019 are summarized as follows ($ in thousands): MSR Other Assets - Derivatives Balance, January 1, 2020 $ 79,394 $ 1,439 Total net (loss) gain included in Mortgage banking, net (1) (42,735 ) 40,669 Additions 29,805 — Sales — (32,548 ) Balance, December 31, 2020 $ 66,464 $ 9,560 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, 2020 $ (26,146 ) $ 25,031 Balance, January 1, 2019 $ 95,596 $ 1,187 Total net (loss) gain included in Mortgage banking, net (1) (32,913 ) 6,775 Additions 16,711 — Sales — (6,523 ) Balance, December 31, 2019 $ 79,394 $ 1,439 The amount of total gains (losses) for the period included in earnings that are attributable to the change in unrealized gains or losses still held at December 31, 2019 $ (21,078 ) $ 1,284 (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, 2020 and 2019 were as follows ($ in thousands): December 31, 2020 December 31, 2019 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Financial Assets: Level 2 Inputs: Cash and short-term investments $ 1,952,554 $ 1,952,554 $ 358,916 $ 358,916 Securities held to maturity 538,072 563,115 738,099 746,202 Level 3 Inputs: Net LHFI and PPP loans 10,317,352 10,312,395 9,251,351 9,235,674 Net acquired loans (1) — — 71,786 71,786 Financial Liabilities: Level 2 Inputs: Deposits 14,048,764 14,052,863 11,245,557 11,250,071 Federal funds purchased and securities sold under repurchase agreements 164,519 164,519 256,020 256,020 Other borrowings 168,252 168,252 85,396 85,374 Subordinated notes 122,921 127,500 — — Junior subordinated debt securities 61,856 46,083 61,856 50,722 (1) Upon adoption of FASB ASC Topic 326 at January 1, 2020, Trustmark elected to account for its existing acquired loans as purchased credit deteriorated loans included within the LHFI portfolio. See Note 5 – Acquired Loans for additional details.
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, 2020 and 2019 ($ in thousands): December 31, 2020 2019 Fair value of LHFS $ 305,791 $ 169,285 LHFS contractual principal outstanding 290,625 164,420 Fair value less unpaid principal $ 15,166 $ 4,865

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 and 2019 as well as the effect of these derivative instruments on Trustmark’s results of operations for the periods presented ($ in thousands): December 31, 2020 2019 Derivatives not designated as hedging instruments Interest rate contracts: Exchange traded purchased options included in other assets $ 145 $ 244 OTC written options (rate locks) included in other assets 9,560 1,439 Interest rate swaps included in other assets (1) 37,974 16,209 Credit risk participation agreements included in other assets 89 64 Futures contracts included in other liabilities 34 2,654 Forward contracts included in other liabilities 3,145 486 Exchange traded written options included in other liabilities 632 1,760 Interest rate swaps included in other liabilities (1) 1,313 1,122 Credit risk participation agreements included in other liabilities 200 41 (1) In accordance with GAAP, the variation margin collateral payments made or received for interest rate swaps that are centrally cleared are legally characterized as settled. As a result, the centrally cleared interest rate swaps included in other assets and other liabilities are presented on a net basis in the accompanying consolidated balance sheets.
Effects of Derivative Instruments on Statements of Operations	Years Ended December 31, 2020 2019 2018 Derivatives in hedging relationships Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) and recognized in other interest expense $ — $ 479 $ 322 Derivatives not designated as hedging instruments Amount of gain (loss) recognized in mortgage banking, net $ 39,436 $ 11,096 $ (6,191 ) Amount of gain (loss) recognized in bank card and other fees (1,022 ) (776 ) (357 )
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, 2020 2019 2018 Derivatives in cash flow hedging relationship Amount of gain (loss) recognized in other comprehensive income (loss), net of tax $ — $ (109 ) $ 373
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, 2020 and 2019 is presented in the following tables ($ in thousands): Offsetting of Derivative Assets As of December 31, 2020 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 $ 37,974 $ — $ 37,974 $ — $ — $ 37,974 Offsetting of Derivative Liabilities As of December 31, 2020 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 $ 1,313 $ — $ 1,313 $ — $ (1,313 ) $ — Offsetting of Derivative Assets As of December 31, 2019 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 $ 16,209 $ — $ 16,209 $ — $ — $ 16,209 Offsetting of Derivative Liabilities As of December 31, 2019 Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Statement of Financial Position Net Amounts of Liabilities presented in the Statement of Financial Position Financial Instruments Cash Collateral Posted Net Amount Derivatives $ 1,122 $ — $ 1,122 $ — $ (1,390 ) $ (268 )

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 2018 General Banking Net interest income $ 420,225 $ 419,597 $ 412,455 Provision for loan losses, net 36,124 10,622 17,098 Noninterest income 197,691 113,756 113,930 Noninterest expense 410,744 367,976 353,174 Income before income taxes 171,048 154,755 156,113 Income taxes 25,109 18,638 18,313 General banking net income $ 145,939 $ 136,117 $ 137,800 Selected Financial Information Total assets $ 16,226,358 $ 13,140,467 $ 12,896,799 Depreciation and amortization $ 40,351 $ 38,634 $ 38,181 Wealth Management Net interest income $ 6,082 $ 6,750 $ 6,739 Provision for loan losses, net (11 ) 217 (110 ) Noninterest income 31,634 30,860 30,420 Noninterest expense 30,318 28,882 31,385 Income before income taxes 7,409 8,511 5,884 Income taxes 1,853 2,123 1,472 Wealth Management net income $ 5,556 $ 6,388 $ 4,412 Selected Financial Information Total assets $ 242,429 $ 283,164 $ 320,742 Depreciation and amortization $ 274 $ 270 $ 187 Insurance Net interest income $ 230 $ 242 $ 226 Noninterest income 45,268 42,429 40,486 Noninterest expense 34,173 32,144 30,856 Income before income taxes 11,325 10,527 9,856 Income taxes 2,795 2,572 2,484 Insurance net income $ 8,530 $ 7,955 $ 7,372 Selected Financial Information Total assets $ 83,053 $ 74,246 $ 68,919 Depreciation and amortization $ 700 $ 516 $ 572 Consolidated Net interest income $ 426,537 $ 426,589 $ 419,420 Provision for loan losses, net 36,113 10,839 16,988 Noninterest income 274,593 187,045 184,836 Noninterest expense 475,235 429,002 415,415 Income before income taxes 189,782 173,793 171,853 Income taxes 29,757 23,333 22,269 Consolidated net income $ 160,025 $ 150,460 $ 149,584 Selected Financial Information Total assets $ 16,551,840 $ 13,497,877 $ 13,286,460 Depreciation and amortization $ 41,325 $ 39,420 $ 38,940

Parent Company Only Financial_2

Parent Company Only Financial Information (Tables)	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Parent Only Financial Statements	Condensed Balance Sheets December 31, 2020 2019 Assets: Investment in banks $ 1,769,165 $ 1,707,644 Other assets 158,360 15,778 Total Assets $ 1,927,525 $ 1,723,422 Liabilities and Shareholders' Equity: Accrued expense $ 1,631 $ 864 Subordinated notes 122,921 — Junior subordinated debt securities 61,856 61,856 Shareholders' equity 1,741,117 1,660,702 Total Liabilities and Shareholders' Equity $ 1,927,525 $ 1,723,422 Condensed Statements of Income Years Ended December 31, 2020 2019 2018 Revenue: Dividends received from banks $ 109,243 $ 120,297 $ 128,592 Earnings of subsidiaries over distributions 53,724 32,971 23,791 Other income 66 90 86 Total Revenue 163,033 153,358 152,469 Expense: Other expense 3,008 2,898 2,885 Total Expense 3,008 2,898 2,885 Net Income $ 160,025 $ 150,460 $ 149,584 Condensed Statements of Cash Flows Years Ended December 31, 2020 2019 2018 Operating Activities: Net income $ 160,025 $ 150,460 $ 149,584 Adjustments to reconcile net income to net cash provided by operating activities: Net change in investment in subsidiaries (53,724 ) (32,971 ) (23,791 ) Other (326 ) (1,800 ) (1,395 ) Net cash from operating activities 105,975 115,689 124,398 Financing Activities: Proceeds from subordinated notes 122,900 — — Common stock dividends (58,769 ) (59,804 ) (62,425 ) Repurchase and retirement of common stock (27,538 ) (56,615 ) (62,421 ) Net cash from financing activities 36,593 (116,419 ) (124,846 ) Net change in cash and cash equivalents 142,568 (730 ) (448 ) Cash and cash equivalents at beginning of year 15,707 16,437 16,885 Cash and cash equivalents at end of year $ 158,275 $ 15,707 $ 16,437

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details)	Jan. 01, 2020USD ($)	Dec. 31, 2020USD ($)OfficeFeeRevenueCategoryContract	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of offices | Office		183
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
Finite-lived intangible assets, average useful life		20 years
Securities with limited marketability		$ 31,700,000	$ 31,900,000
Other-than-temporary impairment of investment in member bank stock		$ 0	0	$ 0
Number of types of interchange fees | Fee		2
Other real estate sales, net (losses) gains		$ 897,000	$ (291,000)	$ 700,000
Number of trust management revenue categories | RevenueCategory		5
Time period between service obligation completed and payment received from trust customer		30 days
Increase to allowance for credit loss on off-balance sheet credit exposures		$ 29,638,000
Fisher Brown Bottrell Insurance, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of general categories of insurance contracts | Contract		4
Credit Card Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due loans are to be charged-off		180 days
Commercial Credits [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due for loan to be classified as nonaccrual		90 days
Non-Business Purpose Credits [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due for loan to be classified as nonaccrual		120 days
Number of days past due loans are to be charged-off		120 days
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days mortgage LHFS are retained on balance sheet		30 days
Minimum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Personal Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period		30 days
Minimum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Employee Benefits Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period		60 days
Minimum [Member] | Furniture and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days mortgage LHFS are retained on balance sheet		45 days
Maximum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Personal Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period		60 days
Maximum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Employee Benefits Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period		90 days
Maximum [Member] | Buildings [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		39 years
Maximum [Member] | Furniture and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		10 years
Maximum [Member] | 1-4 Family Residential Real Estate [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due loans are to be charged-off		180 days
ASU 2016-13 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2020
Change in accounting principle, accounting standards update, adopted [true false]		true
Decrease to loans held for investment, allowance for credit loss	$ 3,000,000
Increase to allowance for credit loss on off-balance sheet credit exposures	29,600,000
One-time cumulative effect adjustment through retained earnings, before tax	26,600,000
One-time cumulative effect adjustment through retained earnings, net of tax	$ 19,900,000
ASU 2016-13 [Member] | Securities Available for Sale [Member]
Summary Of Significant Accounting Policies [Line Items]
Current expected credit loss		$ 0
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2019
Change in accounting principle, accounting standards update, adopted [true false]		true
ASU 2018-15
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2020
Change in accounting principle, accounting standards update, adopted [true false]		true
Change in accounting principle, accounting standards update, immaterial effect [true false]		true
ASU 2018-13
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2020
Change in accounting principle, accounting standards update, adopted [true false]		true
Change in accounting principle, accounting standards update, immaterial effect [true false]		true
ASU 2017-04
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2020
Change in accounting principle, accounting standards update, adopted [true false]		true
ASU 2019-12 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2021
Change in accounting principle, accounting standards update, adopted [true false]		true
ASU 2018-14 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2021
Change in accounting principle, accounting standards update, adopted [true false]		true
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

Significant Accounting Polici_5

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

Significant Accounting Polici_6

Significant Accounting Policies - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of cash flows specific transaction amounts [Abstract]
Income taxes paid	$ 46,648	$ 24,809	$ 12,435
Interest paid on deposits and borrowings	42,968	83,997	66,358
Noncash transfers from loans to other real estate	635	8,598	$ 12,115
Investment in tax credit partnership not funded	5,893	5,000
Finance right-of-use assets resulting from lease liabilities		9,326
Operating right-of-use assets resulting from lease liabilities	3,774	$ 31,182
Transfer of long-term FHLB advances to short-term	$ 651

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share (EPS) [Abstract]
Basic shares	63,505	64,630	67,505
Dilutive shares	141	142	154
Diluted shares	63,646	64,772	67,659

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, 2020	Dec. 31, 2018
Accounting Policies [Abstract]
Weighted-average antidilutive stock awards (in shares)	57	1

Cash and Due from Banks - Addit

Cash and Due from Banks - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash And Cash Equivalents [Abstract]
Average reserve balances with Federal Reserve Bank	$ 19	$ 122.4
Federal reserve tax rate, percent	0.00%

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, 2020	Dec. 31, 2019
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	$ 1,959,773	$ 1,600,984
Securities Available for Sale, Gross Unrealized Gains	33,889	7,580
Securities Available for Sale, Gross Unrealized (Losses)	(1,847)	(6,160)
Securities Available for Sale, Estimated Fair Value	1,991,815	1,602,404
Securities Held to Maturity, Amortized Cost	538,072	738,099
Securities Held to Maturity, Gross Unrealized Gains	25,101	9,274
Securities Held to Maturity, Gross Unrealized (Losses)	(58)	(1,171)
Securities Held to Maturity, Estimated Fair Value	563,115	746,202
U.S. Government Agency Obligations [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Available for Sale, Amortized Cost	18,378	22,965
Securities Available for Sale, Gross Unrealized Gains	144	69
Securities Available for Sale, Gross Unrealized (Losses)	(481)	(707)
Securities Available for Sale, Estimated Fair Value	18,041	22,327
Securities Held to Maturity, Amortized Cost	0	3,781
Securities Held to Maturity, Gross Unrealized Gains	0	220
Securities Held to Maturity, Gross Unrealized (Losses)	0	0
Securities Held to Maturity, Estimated Fair Value	0	4,001
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	5,198	24,952
Securities Available for Sale, Gross Unrealized Gains	637	513
Securities Available for Sale, Gross Unrealized (Losses)	0	0
Securities Available for Sale, Estimated Fair Value	5,835	25,465
Securities Held to Maturity, Amortized Cost	26,584	31,781
Securities Held to Maturity, Gross Unrealized Gains	258	434
Securities Held to Maturity, Gross Unrealized (Losses)	(3)	(53)
Securities Held to Maturity, Estimated Fair Value	26,839	32,162
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	55,193	69,196
Securities Available for Sale, Gross Unrealized Gains	1,672	425
Securities Available for Sale, Gross Unrealized (Losses)	(3)	(369)
Securities Available for Sale, Estimated Fair Value	56,862	69,252
Securities Held to Maturity, Amortized Cost	7,598	10,820
Securities Held to Maturity, Gross Unrealized Gains	382	266
Securities Held to Maturity, Gross Unrealized (Losses)	0	(10)
Securities Held to Maturity, Estimated Fair Value	7,980	11,076
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	1,421,861	714,350
Securities Available for Sale, Gross Unrealized Gains	20,768	2,171
Securities Available for Sale, Gross Unrealized (Losses)	(1,308)	(3,165)
Securities Available for Sale, Estimated Fair Value	1,441,321	713,356
Securities Held to Maturity, Amortized Cost	67,944	96,631
Securities Held to Maturity, Gross Unrealized Gains	2,397	286
Securities Held to Maturity, Gross Unrealized (Losses)	0	(370)
Securities Held to Maturity, Estimated Fair Value	70,341	96,547
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	409,883	656,162
Securities Available for Sale, Gross Unrealized Gains	9,600	3,777
Securities Available for Sale, Gross Unrealized (Losses)	(46)	(1,713)
Securities Available for Sale, Estimated Fair Value	419,437	658,226
Securities Held to Maturity, Amortized Cost	360,361	485,324
Securities Held to Maturity, Gross Unrealized Gains	19,678	7,026
Securities Held to Maturity, Gross Unrealized (Losses)	(55)	(656)
Securities Held to Maturity, Estimated Fair Value	379,984	491,694
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	49,260	113,359
Securities Available for Sale, Gross Unrealized Gains	1,068	625
Securities Available for Sale, Gross Unrealized (Losses)	(9)	(206)
Securities Available for Sale, Estimated Fair Value	50,319	113,778
Securities Held to Maturity, Amortized Cost	75,585	109,762
Securities Held to Maturity, Gross Unrealized Gains	2,386	1,042
Securities Held to Maturity, Gross Unrealized (Losses)	0	(82)
Securities Held to Maturity, Estimated Fair Value	$ 77,971	$ 110,722

Securities Available for Sale_4

Securities Available for Sale and Held to Maturity - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2013
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
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	$ 8,900,000	$ 12,100,000
Net unamortized, unrealized loss on transfer of securities, net of tax	6,700,000	9,100,000
Credit loss recognized	0	0
Potential credit loss exposure	26,600,000
Other-than-temporary impairments		0	$ 0
Pledged to collateralize public deposits and securities sold under repurchase agreements and for other purposes as permitted by law	1,964,000,000	1,770,000,000
Pledged securities providing additional contingency funding	0	$ 0
30 Days or More Past Due [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Held-to-maturity, past due	0
Securities Available for Sale [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Accrued interest receivable	4,000,000
Securities Held to Maturity [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Accrued interest receivable	1,200,000
Reserve for credit loss	0
Held-to-maturity nonnaccrual	$ 0

Securities Available for Sale_5

Securities Available for Sale and Held to Maturity - Securities Held to Maturity by Credit Rating, as Determined by Moody's (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Held to Maturity Amortized Cost	$ 538,072	$ 738,099
Aaa [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Held to Maturity Amortized Cost	511,488
Aaa1 to Aa3 [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Held to Maturity Amortized Cost	22,528
Not Rated [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities Held to Maturity Amortized Cost	$ 4,056

Securities Available for Sale_6

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, 2020	Dec. 31, 2019
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	$ 355,939	$ 352,661
Estimated Fair Value, 12 Months or More	12,493	481,177
Estimated Fair Value, Total	368,432	833,838
Gross Unrealized (Losses), Less than 12 Months	(1,412)	(1,347)
Gross Unrealized (Losses), 12 Months or More	(493)	(5,984)
Gross Unrealized (Losses), Total	(1,905)	(7,331)
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	6,585
Estimated Fair Value, 12 Months or More	11,167	12,886
Estimated Fair Value, Total	11,167	19,471
Gross Unrealized (Losses), Less than 12 Months	0	(105)
Gross Unrealized (Losses), 12 Months or More	(481)	(602)
Gross Unrealized (Losses), Total	(481)	(707)
Obligations of States and Political Subdivisions [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	0	0
Estimated Fair Value, 12 Months or More	667	6,216
Estimated Fair Value, Total	667	6,216
Gross Unrealized (Losses), Less than 12 Months	0	0
Gross Unrealized (Losses), 12 Months or More	(3)	(53)
Gross Unrealized (Losses), Total	(3)	(53)
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	1,636	23,544
Estimated Fair Value, 12 Months or More	0	18,529
Estimated Fair Value, Total	1,636	42,073
Gross Unrealized (Losses), Less than 12 Months	(3)	(107)
Gross Unrealized (Losses), 12 Months or More	0	(272)
Gross Unrealized (Losses), Total	(3)	(379)
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	324,905	112,879
Estimated Fair Value, 12 Months or More	0	278,120
Estimated Fair Value, Total	324,905	390,999
Gross Unrealized (Losses), Less than 12 Months	(1,308)	(230)
Gross Unrealized (Losses), 12 Months or More	0	(3,305)
Gross Unrealized (Losses), Total	(1,308)	(3,535)
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	29,398	158,341
Estimated Fair Value, 12 Months or More	0	151,271
Estimated Fair Value, Total	29,398	309,612
Gross Unrealized (Losses), Less than 12 Months	(101)	(738)
Gross Unrealized (Losses), 12 Months or More	0	(1,631)
Gross Unrealized (Losses), Total	(101)	(2,369)
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	0	51,312
Estimated Fair Value, 12 Months or More	659	14,155
Estimated Fair Value, Total	659	65,467
Gross Unrealized (Losses), Less than 12 Months	0	(167)
Gross Unrealized (Losses), 12 Months or More	(9)	(121)
Gross Unrealized (Losses), Total	$ (9)	$ (288)

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, 2020	Dec. 31, 2019
Securities Available for Sale, Amortized Cost [Abstract]
Due in one year or less	$ 1,570
Due after one year through five years	1,527
Due after five years through ten years	2,031
Due after ten years	18,448
Total amortized cost, before mortgage-backed securities	23,576
Mortgage-backed securities	1,936,197
Securities Available for Sale, Amortized Cost	1,959,773	$ 1,600,984
Securities Available for Sale, Estimated Fair Value [Abstract]
Due in one year or less	1,604
Due after one year through five years	1,570
Due after five years through ten years	1,989
Due after ten years	18,713
Total fair value, before mortgage-backed securities	23,876
Mortgage-backed securities	1,967,939
Total	1,991,815	1,602,404
Securities Held to Maturity, Amortized Cost [Abstract]
Due in one year or less	19,237
Due after one year through five years	7,347
Due after five years through ten years	0
Due after ten years	0
Total amortized cost, before mortgage-backed securities	26,584
Mortgage-backed securities	511,488
Securities Held to Maturity, Amortized Cost	538,072	738,099
Securities Held to Maturity, Estimated Fair Value [Abstract]
Due in one year or less	19,374
Due after one year through five years	7,465
Due after five years through ten years	0
Due after ten years	0
Total fair value, before mortgage-backed securities	26,839
Mortgage-backed securities	536,276
Total	$ 563,115	$ 746,202

Loans Held for Investment (LH_3

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Loan Portfolio Held for Investment (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Loan Portfolio [Abstract]
Total LHFI	[1]	$ 9,824,524	$ 9,335,628
Less allowance for credit losses (ACL), LHFI	[1]	117,306	84,277
Net LHFI		9,707,218	9,251,351
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	[2]	514,056	1,162,791
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	[2]	524,732	1,855,913
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	[2]	1,216,400
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI		1,065,964	724,480
Other Construction [Member] | Other Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	[2]	794,983
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI		2,709,026	2,475,245
Commercial and Industrial Loans [Member]
Loan Portfolio [Abstract]
Total LHFI		1,309,078	1,477,896
Consumer Loans [Member]
Loan Portfolio [Abstract]
Total LHFI		164,386	175,738
State and Other Political Subdivision Loans [Member]
Loan Portfolio [Abstract]
Total LHFI		1,000,776	967,944
Other Commercial Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	[2]	$ 525,123	$ 495,621
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.
[2]	In accordance with the guidance in FASB ASC Topic 326, Trustmark redefined its LHFI portfolio segments and related loan classes based on the level at which risk is monitored within the ACL methodology. The other loans secured by real estate portfolio segment and related loan classes were separated from the loans secured by real estate portfolio segment. The other construction loans were segregated from the construction, land development and other land loans. The other loans secured by 1-4 family residential properties were segregated from the loans secured by 1-4 family residential properties and the loans secured by 1-4 family residential properties were redefined in the other loans secured by real estate portfolio segment. Other loans were redefined as other commercial loans.

Loans Held for Investment (LH_4

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Additional Information (Details 1)	12 Months Ended
	Dec. 31, 2020USD ($)RegionLoan	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Accounts Notes Loans And Financing Receivable Gross Allowance And Net [Abstract]
Accrued interest receivable	$ 33,000,000
Maximum concentration of loan as a percentage of total LHFI	10.00%
Key market regions | Region	5
Loans and Leases Receivable, Related Parties	$ 37,700,000	$ 35,500,000
New loan advances to related party	470,400,000
Loan repayment by related party	468,200,000
Loan increase (decreases) from changes in executive officers and directors	0
Minimum loan amount for loan to be specifically reviewed for impairment and deemed impaired	500,000
LHFI classified as TDRs	25,800,000	31,500,000	$ 28,200,000
LHFI classified as TDRs from credits with interest only payments, payment concessions and credits renewed at a rate that was not commensurate with that of new debt with similar risk	17,700,000
LHFI classified as TDRs from credits with interest only payments and credits renewed at a rate that was not commensurate with that of new debt with similar risk		20,800,000	23,800,000
Unused commitments on TDRs	4,500,000	7,000,000	4,400,000
Financing receivable, related allowance	2,400,000	3,200,000	2,300,000
Financing receivable, related charge-offs	$ 2,300,000	$ 1,600,000	$ 18,400,000
Number of individual loans modified related to COVID-19 | Loan	2,923
Aggregate principal balances of loans modified related to COVID-19	$ 1,271,000,000
Aggregate principal balances of loans modified as troubled debt restructuring related to COVID-19	$ 972,000
Period of extension on interest part of loans modified related to COVID-19	90 days
Period of extension on full payment deferrals part of loans modified related to COVID-19	90 days
Balance of loans remaining under some type of concession related to COVID-19	$ 34,200,000

Loans Held for Investment (LH_5

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Schedule of Amortized Cost Basis of Loans on Nonaccrual Status (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	$ 32,413
Total Nonaccrual	63,128	$ 53,226
Loans Past Due 90 Days or More Still Accruing	1,576
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	5,756
Total Nonaccrual	5,985	897
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	1,895
Total Nonaccrual	4,487
Loans Past Due 90 Days or More Still Accruing	79
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	12,037
Total Nonaccrual	15,197	7,700
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	60
Total Nonaccrual	185	1,032
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Nonaccrual		16,810
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Nonaccrual	11,807
Loans Past Due 90 Days or More Still Accruing	1,257
Commercial and Industrial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	12,665
Total Nonaccrual	15,618	21,775
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Nonaccrual	86	108
Loans Past Due 90 Days or More Still Accruing	240
State and Other Political Subdivision Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Nonaccrual	3,970	$ 4,079
Other Commercial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Nonaccrual	$ 5,793

Loans Held for Investment (LH_6

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Aging Analysis of Past Due and Nonaccrual LHFI by Loan Type (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		$ 24,471	$ 12,627
Nonaccrual		63,128	53,226
Current Loans		9,800,053	9,269,775
Total LHFI		9,824,524	9,335,628
Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		9,615	10,393
Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		5,304	1,592
Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		9,552	642	[1]
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		534	636
Nonaccrual		5,985	897
Current Loans		513,522	1,161,258
Total LHFI		514,056	1,162,791
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		339	380
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		34	256
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		161
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		2,924
Nonaccrual		4,487
Current Loans		521,808
Total LHFI		524,732
Other 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		1,505
Other 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		523
Other 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		896
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due			6,405
Nonaccrual			16,810
Current Loans			1,832,698
Total LHFI			1,855,913
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due			5,254
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due			940
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	[1]		211
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		9,690
Nonaccrual		11,807
Current Loans		1,206,710
Total LHFI		1,216,400
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		3,291
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		1,289
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		5,110
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		1,892	1,698
Nonaccrual		15,197	7,700
Current Loans		2,707,134	2,465,847
Total LHFI		2,709,026	2,475,245
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		920	1,698
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		972
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		311	8
Nonaccrual		185	1,032
Current Loans		1,065,653	723,440
Total LHFI		1,065,964	724,480
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		103	8
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		101
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		107
Commercial and Industrial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		2,010	668
Nonaccrual		15,618	21,775
Current Loans		1,307,068	1,455,453
Total LHFI		1,309,078	1,477,896
Commercial and Industrial Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		271	617
Commercial and Industrial Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		196	12
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		1,543	39	[1]
Other Construction [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current Loans		794,983
Total LHFI		794,983
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		1,356	2,980
Nonaccrual		86	108
Current Loans		163,030	172,650
Total LHFI		164,386	175,738
Consumer Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		926	2,208
Consumer Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		190	380
Consumer Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		240	392	[1]
State and Other Political Subdivision Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		294	76
Nonaccrual		3,970	4,079
Current Loans		1,000,482	963,789
Total LHFI		1,000,776	967,944
State and Other Political Subdivision Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		117	76
State and Other Political Subdivision Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		177
Other Commercial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		5,460
Nonaccrual		5,793
Current Loans		519,663
Total LHFI		525,123
Other Commercial Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		2,143
Other Commercial Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		2,971
Other Commercial Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due		$ 346
Other Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due			156
Nonaccrual			825
Current Loans			494,640
Total LHFI			495,621
Other Loans [Member] | Past Due 30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due			152
Other Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due			$ 4
[1]	Past due 90 days or more but still accruing interest.

Loans Held for Investment (LH_7

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Impaired Financing Receivables (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	$ 47,289
Total LHFI With No Related Allowance Recorded	23,550
Total LHFI With an Allowance Recorded	17,667
Total LHFI Carrying Amount	41,217
Related Allowance	5,459
Average Recorded Investment	48,525
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	926
Total LHFI With No Related Allowance Recorded	610
Total LHFI With an Allowance Recorded	16
Total LHFI Carrying Amount	626
Related Allowance	0
Average Recorded Investment	1,089
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	6,513
Total LHFI With No Related Allowance Recorded	2,104
Total LHFI With an Allowance Recorded	3,360
Total LHFI Carrying Amount	5,464
Related Allowance	35
Average Recorded Investment	4,713
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	7,295
Total LHFI With No Related Allowance Recorded	1,462
Total LHFI With an Allowance Recorded	5,255
Total LHFI Carrying Amount	6,717
Related Allowance	2,355
Average Recorded Investment	8,096
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	69
Total LHFI With No Related Allowance Recorded	0
Total LHFI With an Allowance Recorded	68
Total LHFI Carrying Amount	68
Related Allowance	0
Average Recorded Investment	158
Commercial and Industrial Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	27,178
Total LHFI With No Related Allowance Recorded	19,374
Total LHFI With an Allowance Recorded	4,084
Total LHFI Carrying Amount	23,458
Related Allowance	707
Average Recorded Investment	27,088
Consumer Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	22
Total LHFI With No Related Allowance Recorded	0
Total LHFI With an Allowance Recorded	21
Total LHFI Carrying Amount	21
Related Allowance	0
Average Recorded Investment	11
State and Other Political Subdivision Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	4,079
Total LHFI With No Related Allowance Recorded	0
Total LHFI With an Allowance Recorded	4,079
Total LHFI Carrying Amount	4,079
Related Allowance	1,809
Average Recorded Investment	6,337
Other Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	1,207
Total LHFI With No Related Allowance Recorded	0
Total LHFI With an Allowance Recorded	784
Total LHFI Carrying Amount	784
Related Allowance	553
Average Recorded Investment	$ 1,033

Loans Held for Investment (LH_8

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Impact of Modifications Classified as Troubled Debt Restructurings (Details) - Troubled Debt Restructurings [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)Contract	Dec. 31, 2019USD ($)Contract	Dec. 31, 2018USD ($)Contract
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	27	30	52
Pre-Modification Outstanding Recorded Investment	$ 7,627	$ 15,994	$ 30,878
Post-Modification Outstanding Recorded Investment	$ 7,602	$ 15,877	$ 29,328
Construction, Land Development and Other Land [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract			1
Pre-Modification Outstanding Recorded Investment			$ 22
Post-Modification Outstanding Recorded Investment			$ 22
Secured by 1-4 Family Residential Properties [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract		19	23
Pre-Modification Outstanding Recorded Investment		$ 1,742	$ 2,102
Post-Modification Outstanding Recorded Investment		$ 1,738	$ 1,660
Other Secured by 1-4 Family Residential Properties [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	13
Pre-Modification Outstanding Recorded Investment	$ 923
Post-Modification Outstanding Recorded Investment	$ 929
Secured by Nonfarm, Nonresidential Properties [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	2	1	2
Pre-Modification Outstanding Recorded Investment	$ 1,111	$ 5,055	$ 1,780
Post-Modification Outstanding Recorded Investment	$ 1,111	$ 5,055	$ 1,780
Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	4	8	23
Pre-Modification Outstanding Recorded Investment	$ 1,665	$ 9,167	$ 26,970
Post-Modification Outstanding Recorded Investment	$ 1,664	$ 9,054	$ 25,862
Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	6	2	3
Pre-Modification Outstanding Recorded Investment	$ 26	$ 30	$ 4
Post-Modification Outstanding Recorded Investment	$ 26	$ 30	$ 4
State and Other Political Subdivision Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	2
Pre-Modification Outstanding Recorded Investment	$ 3,902
Post-Modification Outstanding Recorded Investment	$ 3,872

Loans Held for Investment (LH_9

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Troubled Debt Restructuring Subsequently Defaulted (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)Contract	Dec. 31, 2019USD ($)Contract	Dec. 31, 2018USD ($)Contract
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	0	0	1
Recorded Investment | $	$ 0	$ 0	$ 22
Troubled Debt Restructurings [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	4	11	13
Recorded Investment | $	$ 299	$ 665	$ 15,935
Troubled Debt Restructurings [Member] | Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	1	7	6
Recorded Investment | $	$ 82	$ 192	$ 15,178
Troubled Debt Restructurings [Member] | Other Secured by 1-4 Family Residential Properties [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	2	3	5
Recorded Investment | $	$ 78	$ 446	$ 734
Troubled Debt Restructurings [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	1	0	0
Recorded Investment | $	$ 139	$ 0	$ 0
Troubled Debt Restructurings [Member] | Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	0	1	1
Recorded Investment | $	$ 0	$ 27	$ 1

Loans Held for Investment (L_10

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Troubled Debt Restructuring Related to Loans Held for Investment, Excluding Covered Loans, by Loan Type (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable Modifications [Line Items]
Nonaccrual	$ 63,128	$ 53,226
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	5,985	897
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual		16,810
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	4,487
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	15,197	7,700
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	185	1,032
Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	15,618	21,775
Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	86	108
State and Other Political Subdivision Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	3,970	4,079
Other Commercial Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	5,793
Other Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual		825
Troubled Debt Restructurings [Member]
Financing Receivable Modifications [Line Items]
Accruing	1,506	3,396	$ 11,484
Nonaccrual	24,254	28,127	16,706
Total	25,760	31,523	28,190
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	12	15	24
Total	12	15	24
Troubled Debt Restructurings [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing		77	743
Nonaccrual		3,865	3,125
Total		3,942	3,868
Troubled Debt Restructurings [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	0
Nonaccrual	3,699
Total	3,699
Troubled Debt Restructurings [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0	1,734
Nonaccrual	3,903	5,176	395
Total	3,903	5,176	2,129
Troubled Debt Restructurings [Member] | Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	1,500	3,319	9,007
Nonaccrual	12,749	18,913	12,620
Total	14,249	22,232	21,627
Troubled Debt Restructurings [Member] | Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	6	0	0
Nonaccrual	17	21	2
Total	23	21	2
Troubled Debt Restructurings [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0
Nonaccrual	3,793
Total	3,793
Troubled Debt Restructurings [Member] | Other Commercial Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0
Nonaccrual	81
Total	$ 81
Troubled Debt Restructurings [Member] | Other Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing		0	0
Nonaccrual		137	540
Total		$ 137	$ 540

Loans Held for Investment (L_11

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Schedule of Amortized Cost Basis of Collateral-Dependent Loans by Class of Loans and Collateral Type (Details) $ in Thousands	Dec. 31, 2020USD ($)
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	$ 43,409
Loans Secured by Real Estate [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	24,410
Equipment and Machinery [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	425
Inventory and Receivables [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	6,857
Vehicles [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	135
Miscellaneous [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	11,582
Construction, Land Development and Other Land [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	5,756
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	5,756
Other Secured by 1-4 Family Residential Properties [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	454
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	454
Secured by Nonfarm, Nonresidential Properties [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	12,037
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	12,037
Other Real Estate Secured [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	60
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	60
Secured by 1-4 Family Residential Properties [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	1,441
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	1,441
Commercial and Industrial Loans [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	14,076
Commercial and Industrial Loans [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	86
Commercial and Industrial Loans [Member] | Equipment and Machinery [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	425
Commercial and Industrial Loans [Member] | Inventory and Receivables [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	4,899
Commercial and Industrial Loans [Member] | Vehicles [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	135
Commercial and Industrial Loans [Member] | Miscellaneous [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	8,531
State and Other Political Subdivision Loans [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	3,970
State and Other Political Subdivision Loans [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	3,970
Other Commercial Loans [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	5,615
Other Commercial Loans [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	606
Other Commercial Loans [Member] | Inventory and Receivables [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	1,958
Other Commercial Loans [Member] | Miscellaneous [Member]
Financing Receivable Impaired [Line Items]
Collateral-Dependent Loans	$ 3,051

Loans Held for Investment (L_12

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Additional Information (Details 2)		12 Months Ended
		Dec. 31, 2020USD ($)KeyRatio	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Financing Receivable, Recorded Investment, Aging [Abstract]
Number of key quality ratios | KeyRatio		6
Exposure for commercial non accrual loans to be reviewed on individual basis		$ 500,000
Exposure for commercial accrual loans deemed to be reviewed on individual basis		500,000
LHFS past due 90 days or more		119,400,000	$ 41,600,000
Financing Receivable [Abstract]
Provision for credit losses (PCL)	[1]	36,113,000	10,797,000	$ 17,993,000
Allowance for Credit Losses, ACL [Member]
Financing Receivable [Abstract]
Provision for credit losses (PCL)		36,113,000	$ 10,797,000	$ 17,993,000
Commercial and Industrial Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable [Abstract]
Provision for credit losses (PCL)		(2,356,000)
State and Other Political Subdivision Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable [Abstract]
Provision for credit losses (PCL)		(1,494,000)
Minimum [Member]
Financing Receivable [Abstract]
Credit amount used as baseline in evaluating loan policy		$ 100,000
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.

Loans Held for Investment (L_13

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Summary of Amortized Cost Basis of Loans by Credit Quality Indicator (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		$ 2,729,685
Term Loans by Origination Year, 2019		2,007,251
Term Loans by Origination Year, 2018		1,283,113
Term Loans by Origination Year, 2017		697,511
Term Loans by Origination Year, 2016		749,451
Term Loans by Origination Year, Prior to 2016		1,136,893
Financing Receivable, Revolving Loans		1,220,620
Total LHFI	[1]	9,824,524	$ 9,335,628
Commercial and Industrial Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI		1,309,078	1,477,896
State and Other Political Subdivision Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI		1,000,776	967,944
Other Commercial Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI	[2]	525,123	495,621
Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI		164,386	175,738
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI	[2]	514,056	1,162,791
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI	[2]	524,732	1,855,913
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI		1,065,964	724,480
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI		2,709,026	2,475,245
Other Loans Secured by Real Estate [Member] | Other Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI	[2]	794,983
Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI	[2]	1,216,400
Commercial LHFI [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		2,304,725
Term Loans by Origination Year, 2019		1,731,911
Term Loans by Origination Year, 2018		1,072,826
Term Loans by Origination Year, 2017		593,152
Term Loans by Origination Year, 2016		634,209
Term Loans by Origination Year, Prior to 2016		791,222
Financing Receivable, Revolving Loans		814,179
Total LHFI		7,942,224	7,348,158
Commercial LHFI [Member] | Pass - RR 1 through RR 6 [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI			7,178,617
Commercial LHFI [Member] | Special Mention - RR 7 [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI			9,049
Commercial LHFI [Member] | Substandard - RR 8 [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI			159,163
Commercial LHFI [Member] | Doubtful - RR 9 [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI			1,329
Commercial LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		457,222
Term Loans by Origination Year, 2019		167,117
Term Loans by Origination Year, 2018		87,348
Term Loans by Origination Year, 2017		81,720
Term Loans by Origination Year, 2016		61,323
Term Loans by Origination Year, Prior to 2016		48,242
Financing Receivable, Revolving Loans		406,106
Total LHFI		1,309,078	1,477,896
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Pass - RR 1 through RR 6 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		444,304
Term Loans by Origination Year, 2019		165,163
Term Loans by Origination Year, 2018		77,611
Term Loans by Origination Year, 2017		77,985
Term Loans by Origination Year, 2016		59,131
Term Loans by Origination Year, Prior to 2016		43,214
Financing Receivable, Revolving Loans		372,486
Total LHFI		1,239,894	1,407,837
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Special Mention - RR 7 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		677
Term Loans by Origination Year, 2019		45
Financing Receivable, Revolving Loans		240
Total LHFI		962	909
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Substandard - RR 8 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		12,090
Term Loans by Origination Year, 2019		1,814
Term Loans by Origination Year, 2018		9,737
Term Loans by Origination Year, 2017		3,735
Term Loans by Origination Year, 2016		2,160
Term Loans by Origination Year, Prior to 2016		5,024
Financing Receivable, Revolving Loans		33,380
Total LHFI		67,940	68,262
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Doubtful - RR 9 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		151
Term Loans by Origination Year, 2019		95
Term Loans by Origination Year, 2016		32
Term Loans by Origination Year, Prior to 2016		4
Total LHFI		282	888
Commercial LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		250,363
Term Loans by Origination Year, 2019		79,595
Term Loans by Origination Year, 2018		41,334
Term Loans by Origination Year, 2017		114,064
Term Loans by Origination Year, 2016		132,634
Term Loans by Origination Year, Prior to 2016		381,340
Financing Receivable, Revolving Loans		1,446
Total LHFI		1,000,776	967,944
Commercial LHFI [Member] | State and Other Political Subdivision Loans [Member] | Pass - RR 1 through RR 6 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		250,363
Term Loans by Origination Year, 2019		79,595
Term Loans by Origination Year, 2018		41,334
Term Loans by Origination Year, 2017		113,817
Term Loans by Origination Year, 2016		132,634
Term Loans by Origination Year, Prior to 2016		372,831
Financing Receivable, Revolving Loans		1,446
Total LHFI		992,020	957,948
Commercial LHFI [Member] | State and Other Political Subdivision Loans [Member] | Special Mention - RR 7 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, Prior to 2016		4,018
Total LHFI		4,018	4,650
Commercial LHFI [Member] | State and Other Political Subdivision Loans [Member] | Substandard - RR 8 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2017		247
Term Loans by Origination Year, Prior to 2016		4,491
Total LHFI		4,738	5,346
Commercial LHFI [Member] | Other Commercial Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		109,113
Term Loans by Origination Year, 2019		73,089
Term Loans by Origination Year, 2018		21,452
Term Loans by Origination Year, 2017		9,729
Term Loans by Origination Year, 2016		34,188
Term Loans by Origination Year, Prior to 2016		30,738
Financing Receivable, Revolving Loans		246,814
Total LHFI		525,123
Commercial LHFI [Member] | Other Commercial Loans [Member] | Pass - RR 1 through RR 6 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		101,230
Term Loans by Origination Year, 2019		70,990
Term Loans by Origination Year, 2018		20,769
Term Loans by Origination Year, 2017		9,723
Term Loans by Origination Year, 2016		33,481
Term Loans by Origination Year, Prior to 2016		30,715
Financing Receivable, Revolving Loans		225,533
Total LHFI		492,441
Commercial LHFI [Member] | Other Commercial Loans [Member] | Special Mention - RR 7 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		7,500
Financing Receivable, Revolving Loans		11,333
Total LHFI		18,833
Commercial LHFI [Member] | Other Commercial Loans [Member] | Substandard - RR 8 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		381
Term Loans by Origination Year, 2019		2,099
Term Loans by Origination Year, 2018		683
Term Loans by Origination Year, 2017		6
Term Loans by Origination Year, 2016		707
Financing Receivable, Revolving Loans		9,948
Total LHFI		13,824
Commercial LHFI [Member] | Other Commercial Loans [Member] | Doubtful - RR 9 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		2
Term Loans by Origination Year, Prior to 2016		23
Total LHFI		25
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		292,637
Term Loans by Origination Year, 2019		66,441
Term Loans by Origination Year, 2018		27,627
Term Loans by Origination Year, 2017		4,499
Term Loans by Origination Year, 2016		3,768
Term Loans by Origination Year, Prior to 2016		3,628
Financing Receivable, Revolving Loans		28,649
Total LHFI		427,249
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Pass - RR 1 through RR 6 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		287,218
Term Loans by Origination Year, 2019		62,078
Term Loans by Origination Year, 2018		26,401
Term Loans by Origination Year, 2017		4,487
Term Loans by Origination Year, 2016		3,274
Term Loans by Origination Year, Prior to 2016		3,564
Financing Receivable, Revolving Loans		28,548
Total LHFI		415,570
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Substandard - RR 8 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		5,419
Term Loans by Origination Year, 2019		4,363
Term Loans by Origination Year, 2018		1,226
Term Loans by Origination Year, 2017		12
Term Loans by Origination Year, 2016		494
Term Loans by Origination Year, Prior to 2016		22
Financing Receivable, Revolving Loans		101
Total LHFI		11,637
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Doubtful - RR 9 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, Prior to 2016		42
Total LHFI		42
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		36,578
Term Loans by Origination Year, 2019		19,604
Term Loans by Origination Year, 2018		16,363
Term Loans by Origination Year, 2017		9,946
Term Loans by Origination Year, 2016		10,575
Term Loans by Origination Year, Prior to 2016		5,123
Financing Receivable, Revolving Loans		12,436
Total LHFI		110,625
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Pass - RR 1 through RR 6 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		35,139
Term Loans by Origination Year, 2019		19,596
Term Loans by Origination Year, 2018		15,399
Term Loans by Origination Year, 2017		9,605
Term Loans by Origination Year, 2016		10,273
Term Loans by Origination Year, Prior to 2016		4,786
Financing Receivable, Revolving Loans		8,486
Total LHFI		103,284
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Special Mention - RR 7 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		255
Term Loans by Origination Year, 2018		50
Total LHFI		305
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Substandard - RR 8 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		1,155
Term Loans by Origination Year, 2019		8
Term Loans by Origination Year, 2018		914
Term Loans by Origination Year, 2017		341
Term Loans by Origination Year, 2016		302
Term Loans by Origination Year, Prior to 2016		337
Financing Receivable, Revolving Loans		3,950
Total LHFI		7,007
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Doubtful - RR 9 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		29
Total LHFI		29
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		165,452
Term Loans by Origination Year, 2019		376,779
Term Loans by Origination Year, 2018		347,490
Term Loans by Origination Year, 2017		48,626
Term Loans by Origination Year, 2016		90,380
Term Loans by Origination Year, Prior to 2016		24,643
Financing Receivable, Revolving Loans		12,116
Total LHFI		1,065,486
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Pass - RR 1 through RR 6 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		146,803
Term Loans by Origination Year, 2019		376,765
Term Loans by Origination Year, 2018		347,472
Term Loans by Origination Year, 2017		48,626
Term Loans by Origination Year, 2016		89,824
Term Loans by Origination Year, Prior to 2016		23,680
Financing Receivable, Revolving Loans		12,116
Total LHFI		1,045,286
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Special Mention - RR 7 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, Prior to 2016		841
Total LHFI		841
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Substandard - RR 8 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		18,649
Term Loans by Origination Year, 2019		14
Term Loans by Origination Year, 2018		18
Term Loans by Origination Year, 2016		556
Term Loans by Origination Year, Prior to 2016		122
Total LHFI		19,359
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		730,062
Term Loans by Origination Year, 2019		523,350
Term Loans by Origination Year, 2018		449,736
Term Loans by Origination Year, 2017		310,494
Term Loans by Origination Year, 2016		298,877
Term Loans by Origination Year, Prior to 2016		297,508
Financing Receivable, Revolving Loans		98,877
Total LHFI		2,708,904	2,475,090
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Pass - RR 1 through RR 6 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		697,439
Term Loans by Origination Year, 2019		496,476
Term Loans by Origination Year, 2018		442,264
Term Loans by Origination Year, 2017		293,072
Term Loans by Origination Year, 2016		254,747
Term Loans by Origination Year, Prior to 2016		251,219
Financing Receivable, Revolving Loans		96,098
Total LHFI		2,531,315	2,430,761
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Special Mention - RR 7 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		13,452
Term Loans by Origination Year, 2019		6,139
Term Loans by Origination Year, 2018		2,956
Term Loans by Origination Year, 2017		4,466
Term Loans by Origination Year, 2016		4,957
Term Loans by Origination Year, Prior to 2016		20,545
Total LHFI		52,515
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Substandard - RR 8 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		19,119
Term Loans by Origination Year, 2019		20,572
Term Loans by Origination Year, 2018		4,516
Term Loans by Origination Year, 2017		12,956
Term Loans by Origination Year, 2016		38,956
Term Loans by Origination Year, Prior to 2016		25,438
Financing Receivable, Revolving Loans		2,779
Total LHFI		124,336	44,001
Commercial LHFI [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Doubtful - RR 9 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		52
Term Loans by Origination Year, 2019		163
Term Loans by Origination Year, 2016		217
Term Loans by Origination Year, Prior to 2016		306
Total LHFI		738	328
Commercial LHFI [Member] | Other Loans Secured by Real Estate [Member] | Other Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		263,298
Term Loans by Origination Year, 2019		425,936
Term Loans by Origination Year, 2018		81,476
Term Loans by Origination Year, 2017		14,074
Term Loans by Origination Year, 2016		2,464
Financing Receivable, Revolving Loans		7,735
Total LHFI		794,983
Commercial LHFI [Member] | Other Loans Secured by Real Estate [Member] | Other Construction [Member] | Pass - RR 1 through RR 6 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		262,544
Term Loans by Origination Year, 2019		425,936
Term Loans by Origination Year, 2018		81,476
Term Loans by Origination Year, 2017		14,074
Term Loans by Origination Year, 2016		2,464
Financing Receivable, Revolving Loans		7,735
Total LHFI		794,229
Commercial LHFI [Member] | Other Loans Secured by Real Estate [Member] | Other Construction [Member] | Substandard - RR 8 [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		754
Total LHFI		754
Consumer LHFI [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		424,960
Term Loans by Origination Year, 2019		275,340
Term Loans by Origination Year, 2018		210,287
Term Loans by Origination Year, 2017		104,359
Term Loans by Origination Year, 2016		115,242
Term Loans by Origination Year, Prior to 2016		345,671
Financing Receivable, Revolving Loans		406,441
Total LHFI		1,882,300	9,335,628
Consumer LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI			1,477,896
Consumer LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total LHFI			967,944
Consumer LHFI [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		65,983
Term Loans by Origination Year, 2019		25,465
Term Loans by Origination Year, 2018		13,266
Term Loans by Origination Year, 2017		3,925
Term Loans by Origination Year, 2016		1,266
Term Loans by Origination Year, Prior to 2016		348
Financing Receivable, Revolving Loans		54,133
Total LHFI		164,386	175,738
Consumer LHFI [Member] | Consumer Loans [Member] | Current [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		65,370
Term Loans by Origination Year, 2019		25,303
Term Loans by Origination Year, 2018		13,140
Term Loans by Origination Year, 2017		3,893
Term Loans by Origination Year, 2016		1,257
Term Loans by Origination Year, Prior to 2016		345
Financing Receivable, Revolving Loans		53,669
Total LHFI		162,977
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 30-89 Days [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		524
Term Loans by Origination Year, 2019		158
Term Loans by Origination Year, 2018		67
Term Loans by Origination Year, 2017		19
Term Loans by Origination Year, 2016		7
Term Loans by Origination Year, Prior to 2016		3
Financing Receivable, Revolving Loans		305
Total LHFI		1,083
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		77
Term Loans by Origination Year, 2018		4
Financing Receivable, Revolving Loans		159
Total LHFI		240
Consumer LHFI [Member] | Consumer Loans [Member] | Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		12
Term Loans by Origination Year, 2019		4
Term Loans by Origination Year, 2018		55
Term Loans by Origination Year, 2017		13
Term Loans by Origination Year, 2016		2
Total LHFI		86
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		47,336
Term Loans by Origination Year, 2019		24,492
Term Loans by Origination Year, 2018		8,516
Term Loans by Origination Year, 2017		2,036
Term Loans by Origination Year, 2016		1,448
Term Loans by Origination Year, Prior to 2016		2,979
Total LHFI		86,807
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Current [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		47,336
Term Loans by Origination Year, 2019		24,174
Term Loans by Origination Year, 2018		8,496
Term Loans by Origination Year, 2017		2,036
Term Loans by Origination Year, 2016		1,447
Term Loans by Origination Year, Prior to 2016		2,868
Total LHFI		86,357
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Past Due 30-89 Days [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2019		318
Term Loans by Origination Year, 2018		20
Term Loans by Origination Year, 2016		1
Term Loans by Origination Year, Prior to 2016		12
Total LHFI		351
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, Prior to 2016		99
Total LHFI		99
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		20,963
Term Loans by Origination Year, 2019		10,309
Term Loans by Origination Year, 2018		12,158
Term Loans by Origination Year, 2017		4,618
Term Loans by Origination Year, 2016		2,082
Term Loans by Origination Year, Prior to 2016		11,669
Financing Receivable, Revolving Loans		352,308
Total LHFI		414,107
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Current [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		20,864
Term Loans by Origination Year, 2019		10,253
Term Loans by Origination Year, 2018		12,037
Term Loans by Origination Year, 2017		4,177
Term Loans by Origination Year, 2016		2,082
Term Loans by Origination Year, Prior to 2016		11,124
Financing Receivable, Revolving Loans		348,830
Total LHFI		409,367
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Past Due 30-89 Days [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		93
Term Loans by Origination Year, 2019		12
Term Loans by Origination Year, 2017		13
Term Loans by Origination Year, Prior to 2016		133
Financing Receivable, Revolving Loans		1,058
Total LHFI		1,309
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Past Due 90 Days or More [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, Prior to 2016		30
Financing Receivable, Revolving Loans		22
Total LHFI		52
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		6
Term Loans by Origination Year, 2019		44
Term Loans by Origination Year, 2018		121
Term Loans by Origination Year, 2017		428
Term Loans by Origination Year, Prior to 2016		382
Financing Receivable, Revolving Loans		2,398
Total LHFI		3,379
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		107
Term Loans by Origination Year, 2018		38
Term Loans by Origination Year, 2017		37
Term Loans by Origination Year, 2016		96
Term Loans by Origination Year, Prior to 2016		200
Total LHFI		478
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Current [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		107
Term Loans by Origination Year, 2018		38
Term Loans by Origination Year, 2017		37
Term Loans by Origination Year, 2016		96
Term Loans by Origination Year, Prior to 2016		200
Total LHFI		478
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		109
Term Loans by Origination Year, 2017		4
Term Loans by Origination Year, Prior to 2016		9
Total LHFI		122	$ 2,475,245
Consumer LHFI [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Current [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		109
Term Loans by Origination Year, 2017		4
Term Loans by Origination Year, Prior to 2016		9
Total LHFI		122
Consumer LHFI [Member] | Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		290,462
Term Loans by Origination Year, 2019		215,074
Term Loans by Origination Year, 2018		176,309
Term Loans by Origination Year, 2017		93,739
Term Loans by Origination Year, 2016		110,350
Term Loans by Origination Year, Prior to 2016		330,466
Total LHFI		1,216,400
Consumer LHFI [Member] | Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Current [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		289,521
Term Loans by Origination Year, 2019		214,056
Term Loans by Origination Year, 2018		173,324
Term Loans by Origination Year, 2017		92,564
Term Loans by Origination Year, 2016		109,031
Term Loans by Origination Year, Prior to 2016		321,250
Total LHFI		1,199,746
Consumer LHFI [Member] | Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Past Due 30-89 Days [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		499
Term Loans by Origination Year, 2019		93
Term Loans by Origination Year, 2018		753
Term Loans by Origination Year, 2017		366
Term Loans by Origination Year, 2016		1,080
Term Loans by Origination Year, Prior to 2016		799
Total LHFI		3,590
Consumer LHFI [Member] | Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Past Due 90 Days or More [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		159
Term Loans by Origination Year, 2019		214
Term Loans by Origination Year, 2018		208
Term Loans by Origination Year, 2017		127
Term Loans by Origination Year, Prior to 2016		549
Total LHFI		1,257
Consumer LHFI [Member] | Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Term Loans by Origination Year, 2020		283
Term Loans by Origination Year, 2019		711
Term Loans by Origination Year, 2018		2,024
Term Loans by Origination Year, 2017		682
Term Loans by Origination Year, 2016		239
Term Loans by Origination Year, Prior to 2016		7,868
Total LHFI		$ 11,807
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.
[2]	In accordance with the guidance in FASB ASC Topic 326, Trustmark redefined its LHFI portfolio segments and related loan classes based on the level at which risk is monitored within the ACL methodology. The other loans secured by real estate portfolio segment and related loan classes were separated from the loans secured by real estate portfolio segment. The other construction loans were segregated from the construction, land development and other land loans. The other loans secured by 1-4 family residential properties were segregated from the loans secured by 1-4 family residential properties and the loans secured by 1-4 family residential properties were redefined in the other loans secured by real estate portfolio segment. Other loans were redefined as other commercial loans.

Loans Held for Investment (L_14

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Summary of LHFI by Loan Type and Credit Quality Indicator (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Financing Receivable [Abstract]
Loans held for investment (LHFI)	[1]	$ 9,824,524	$ 9,335,628
Current		9,800,053	9,269,775
Financing Receivable, Recorded Investment, Past Due		24,471	12,627
Nonaccrual		63,128	53,226
Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		9,552	642	[2]
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current			1,832,698
Financing Receivable, Recorded Investment, Past Due			6,405
Nonaccrual			16,810
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	[2]		211
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		2,709,026	2,475,245
Current		2,707,134	2,465,847
Financing Receivable, Recorded Investment, Past Due		1,892	1,698
Nonaccrual		15,197	7,700
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		972
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current		1,065,653	723,440
Financing Receivable, Recorded Investment, Past Due		311	8
Nonaccrual		185	1,032
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		107
Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		1,309,078	1,477,896
Current		1,307,068	1,455,453
Financing Receivable, Recorded Investment, Past Due		2,010	668
Nonaccrual		15,618	21,775
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		1,543	39	[2]
Consumer Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		164,386	175,738
Current		163,030	172,650
Financing Receivable, Recorded Investment, Past Due		1,356	2,980
Nonaccrual		86	108
Consumer Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		240	392	[2]
State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		1,000,776	967,944
Current		1,000,482	963,789
Financing Receivable, Recorded Investment, Past Due		294	76
Nonaccrual		3,970	4,079
State and Other Political Subdivision Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		177
Other Loans [Member]
Financing Receivable [Abstract]
Current			494,640
Financing Receivable, Recorded Investment, Past Due			156
Nonaccrual			825
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Current		513,522	1,161,258
Financing Receivable, Recorded Investment, Past Due		534	636
Nonaccrual		5,985	897
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due		161
Commercial LHFI [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		7,942,224	7,348,158
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			123,033
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		2,708,904	2,475,090
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			723,785
Commercial LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		1,309,078	1,477,896
Commercial LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		1,000,776	967,944
Commercial LHFI [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			489,496
Commercial LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			1,090,914
Commercial LHFI [Member] | Pass - RR 1 through RR 6 [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			7,178,617
Commercial LHFI [Member] | Pass - RR 1 through RR 6 [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			116,592
Commercial LHFI [Member] | Pass - RR 1 through RR 6 [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		2,531,315	2,430,761
Commercial LHFI [Member] | Pass - RR 1 through RR 6 [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			721,238
Commercial LHFI [Member] | Pass - RR 1 through RR 6 [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		1,239,894	1,407,837
Commercial LHFI [Member] | Pass - RR 1 through RR 6 [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		992,020	957,948
Commercial LHFI [Member] | Pass - RR 1 through RR 6 [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			469,095
Commercial LHFI [Member] | Pass - RR 1 through RR 6 [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			1,075,146
Commercial LHFI [Member] | Special Mention - RR 7 [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			9,049
Commercial LHFI [Member] | Special Mention - RR 7 [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			45
Commercial LHFI [Member] | Special Mention - RR 7 [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		52,515
Commercial LHFI [Member] | Special Mention - RR 7 [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		962	909
Commercial LHFI [Member] | Special Mention - RR 7 [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		4,018	4,650
Commercial LHFI [Member] | Special Mention - RR 7 [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			3,445
Commercial LHFI [Member] | Substandard - RR 8 [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			159,163
Commercial LHFI [Member] | Substandard - RR 8 [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			6,355
Commercial LHFI [Member] | Substandard - RR 8 [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		124,336	44,001
Commercial LHFI [Member] | Substandard - RR 8 [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			2,547
Commercial LHFI [Member] | Substandard - RR 8 [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		67,940	68,262
Commercial LHFI [Member] | Substandard - RR 8 [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		4,738	5,346
Commercial LHFI [Member] | Substandard - RR 8 [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			16,926
Commercial LHFI [Member] | Substandard - RR 8 [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			15,726
Commercial LHFI [Member] | Doubtful - RR 9 [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			1,329
Commercial LHFI [Member] | Doubtful - RR 9 [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			41
Commercial LHFI [Member] | Doubtful - RR 9 [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		738	328
Commercial LHFI [Member] | Doubtful - RR 9 [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		282	888
Commercial LHFI [Member] | Doubtful - RR 9 [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			30
Commercial LHFI [Member] | Doubtful - RR 9 [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			42
Consumer LHFI [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		1,882,300	9,335,628
Current			1,961,967
Nonaccrual			16,057
Subtotal			1,987,470
Consumer LHFI [Member] | Past Due 30-89 Days [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due			8,842
Consumer LHFI [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due			604
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			1,855,913
Current			1,710,930
Nonaccrual			15,817
Subtotal			1,732,880
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30-89 Days [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due			5,922
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due			211
Consumer LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		122	2,475,245
Current			155
Subtotal			155
Consumer LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			724,480
Current			695
Subtotal			695
Consumer LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			1,477,896
Consumer LHFI [Member] | Consumer Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		164,386	175,738
Current			172,649
Nonaccrual			108
Subtotal			175,738
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 30-89 Days [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		1,083
Financing Receivable, Recorded Investment, Past Due			2,588
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)		$ 240
Financing Receivable, Recorded Investment, Past Due			393
Consumer LHFI [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			967,944
Consumer LHFI [Member] | Other Loans [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			495,621
Current			6,125
Subtotal			6,125
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable [Abstract]
Loans held for investment (LHFI)			1,162,791
Current			71,413
Nonaccrual			132
Subtotal			71,877
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 30-89 Days [Member]
Financing Receivable [Abstract]
Financing Receivable, Recorded Investment, Past Due			$ 332
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.
[2]	Past due 90 days or more but still accruing interest.

Loans Held for Investment (L_15

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Summary of Trustmark's Portfolio Segments, Loan Classes, Loan Pools and the ACL Methodology and Loss Drivers (Details)	12 Months Ended
	Dec. 31, 2020
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | 1 -4 Family Residential Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Prime Rate, National GDP
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Lots and Development [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Prime Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Unimproved Land [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Prime Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | All Other Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Prime Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | All Other Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Prime Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Consumer 1-4 Family - 1st Liens [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Prime Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Nonresidential Owner- Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Southern Unemployment, National GDP
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonresidential Owner- Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Southern Unemployment, National GDP
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonowner-Occupied - Hotel/Motel [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Southern Vacancy Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonowner-Occupied - Office [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Southern Vacancy Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonowner-Occupied- Retail [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Southern Vacancy Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonowner-Occupied- Senior Living/ Nursing Homes [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Southern Vacancy Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonowner-occupied - All Other [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Southern Vacancy Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Nonresidential Owner- Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Southern Unemployment, National GDP
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Nonowner-occupied - All Other [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Southern Vacancy Rate, Southern Unemployment
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Nonresidential Nonowner- Occupied - Apartments [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Southern Vacancy Rate, Southern Unemployment
Other Loans Secured by Real Estate [Member] | Other Construction [Member] | Other Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	WARM
Loss Drivers	Prime Rate, National Unemployment
Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Trustmark Mortgage [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	WARM
Loss Drivers	Southern Unemployment
Commercial and Industrial Loans [Member] | Commercial and Industrial Loans [Member] | Commercial and Industrial - Non-Working Capital [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Trustmark historical data
Commercial and Industrial Loans [Member] | Commercial and Industrial Loans [Member] | Commercial and Industrial - Working Capital [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Trustmark historical data
Commercial and Industrial Loans [Member] | Commercial and Industrial Loans [Member] | Credit Cards [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	WARM
Loss Drivers	Trustmark call report data
Consumer Loans [Member] | Consumer Loans [Member] | All Other Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Prime Rate, Southern Unemployment
Consumer Loans [Member] | Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	WARM
Loss Drivers	Trustmark call report data
Consumer Loans [Member] | Consumer Loans [Member] | Overdrafts [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	Loss Rate
Loss Drivers	Trustmark historical data
State and Other Political Subdivision Loans [Member] | State and Other Political Subdivision Loans [Member] | Obligations of State and Political Subdivisions [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Moody's Bond Default Study
Other Commercial Loans [Member] | Other Commercial Loans [Member] | Commercial and Industrial - Non-Working Capital [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Trustmark historical data
Other Commercial Loans [Member] | Other Commercial Loans [Member] | Commercial and Industrial - Working Capital [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Trustmark historical data
Other Commercial Loans [Member] | Other Commercial Loans [Member] | Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Methodology	DCF
Loss Drivers	Prime Rate, Southern Unemployment

Loans Held for Investment (L_16

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Summary of Balance in Allowance for Loan Losses (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss			$ 5,500
Total	[1]	$ 117,306	84,277
Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		4,379	5,459
Collectively Evaluated for Credit Loss		112,927	78,818
Total		117,306	84,277	$ 79,290	$ 76,733
Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		43,409	41,217
Collectively Evaluated for Credit Loss		9,781,115	9,294,411
Total		9,824,524	9,335,628
Commercial and Industrial Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		579	707
Collectively Evaluated for Credit Loss		14,272	25,285
Total		14,851	25,992
Commercial and Industrial Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		14,076	23,458
Collectively Evaluated for Credit Loss		1,295,002	1,454,438
Total		1,309,078	1,477,896
Consumer Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss		5,838	3,379
Total		5,838	3,379
Consumer Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss			21
Collectively Evaluated for Credit Loss		164,386	175,717
Total		164,386	175,738
State and Other Political Subdivision Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		1,700	1,809
Collectively Evaluated for Credit Loss		1,490	420
Total		3,190	2,229
State and Other Political Subdivision Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		3,970	4,079
Collectively Evaluated for Credit Loss		996,806	963,865
Total		1,000,776	967,944
Other Commercial Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		2,100
Collectively Evaluated for Credit Loss		5,339
Total		7,439	5,303
Other Commercial Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		5,615
Collectively Evaluated for Credit Loss		519,508
Total		525,123
Other Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss			553
Collectively Evaluated for Credit Loss			4,750
Total			5,303
Other Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss			784
Collectively Evaluated for Credit Loss			494,837
Total			495,621
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss		6,854	8,260
Total		6,854	8,260
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		5,756	626
Collectively Evaluated for Credit Loss		508,300	1,162,165
Total		514,056	1,162,791
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss		9,928
Total		9,928	5,888
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		454
Collectively Evaluated for Credit Loss		524,278
Total		524,732
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss			2,355
Collectively Evaluated for Credit Loss		48,523	23,803
Total		48,523	26,158
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		12,037	6,717
Collectively Evaluated for Credit Loss		2,696,989	2,468,528
Total		2,709,026	2,475,245
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss		7,382	4,024
Total		7,382	4,024
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		60	68
Collectively Evaluated for Credit Loss		1,065,904	724,412
Total		1,065,964	724,480
Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss			35
Collectively Evaluated for Credit Loss			8,897
Total			8,932
Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss			5,464
Collectively Evaluated for Credit Loss			1,850,449
Total			1,855,913
Other Loans Secured by Real Estate [Member] | Other Construction [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss		8,158
Total		8,158	1,889
Other Loans Secured by Real Estate [Member] | Other Construction [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss		794,983
Total		794,983
Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss		5,143
Total		5,143	$ 3,044
Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		1,441
Collectively Evaluated for Credit Loss		1,214,959
Total		$ 1,216,400
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.

Loans Held for Investment (L_17

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Change in Allowance for Loan Losses (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	[1]	$ 84,277
Provision for credit losses (PCL)	[1]	36,113	$ 10,797	$ 17,993
Balance at end of period	[1]	117,306	84,277
Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		84,277	79,290	76,733
Transfers	[2]			1,554
Loans charged-off		(11,475)	(14,481)	(29,489)
Recoveries		9,608	8,671	12,499
Net (charge-offs) recoveries		(1,867)	(5,810)	(16,990)
Provision for credit losses (PCL)		36,113	10,797	17,993
Balance at end of period		117,306	84,277	79,290
Allowance for Credit Losses, ACL [Member] | Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		25,992
Loans charged-off		(1,557)
Recoveries		1,736
Provision for credit losses (PCL)		(2,356)
Balance at end of period		14,851	25,992
Allowance for Credit Losses, ACL [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		3,379
Loans charged-off		(2,039)
Recoveries		1,824
Provision for credit losses (PCL)		615
Balance at end of period		5,838	3,379
Allowance for Credit Losses, ACL [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		2,229
Provision for credit losses (PCL)		(1,494)
Balance at end of period		3,190	2,229
Allowance for Credit Losses, ACL [Member] | Other Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		5,303
Loans charged-off		(3,922)
Recoveries		3,929
Provision for credit losses (PCL)		45
Balance at end of period		7,439	5,303
Allowance for Credit Losses, ACL [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		5,303
Balance at end of period			5,303
Allowance for Credit Losses, ACL [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		8,260
Balance at end of period		6,854	8,260
Allowance for Credit Losses, ACL [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Commercial LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		6,371
Loans charged-off		(12)
Recoveries		716
Provision for credit losses (PCL)		(33)
Balance at end of period		6,854	6,371
Allowance for Credit Losses, ACL [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		5,888
Loans charged-off		(117)
Recoveries		378
Provision for credit losses (PCL)		(409)
Balance at end of period		9,928	5,888
Allowance for Credit Losses, ACL [Member] | Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		8,932
Balance at end of period			8,932
Allowance for Credit Losses, ACL [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		26,158
Loans charged-off		(3,777)
Recoveries		546
Provision for credit losses (PCL)		33,775
Balance at end of period		48,523	26,158
Allowance for Credit Losses, ACL [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		4,024
Loans charged-off		(8)
Recoveries		68
Provision for credit losses (PCL)		4,063
Balance at end of period		7,382	4,024
Allowance for Credit Losses, ACL [Member] | Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		3,044
Loans charged-off		(43)
Recoveries		203
Provision for credit losses (PCL)		(952)
Balance at end of period		5,143	3,044
Allowance for Credit Losses, ACL [Member] | Other Loans Secured by Real Estate [Member] | Other Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		1,889
Recoveries		208
Provision for credit losses (PCL)		2,859
Balance at end of period		8,158	1,889
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
LHFI		(3,039)
Allowance for loan losses, acquired loans transfer		815
Acquired loans ACL adjustment		1,007
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		(1,217)
Balance at end of period			(1,217)
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Commercial and Industrial Loans [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		(8,964)
Balance at end of period			(8,964)
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Consumer Loans [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		2,059
Balance at end of period			2,059
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | State and Other Political Subdivision Loans [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		2,455
Balance at end of period			2,455
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Other Commercial Loans [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		2,084
Balance at end of period			2,084
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Cumulative Effect Period Of Adoption Adjustment [Member] | Commercial LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		(188)
Balance at end of period			(188)
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		4,188
Balance at end of period			4,188
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		(8,179)
Balance at end of period			(8,179)
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		(765)
Balance at end of period			(765)
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		2,891
Balance at end of period			2,891
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Other Loans Secured by Real Estate [Member] | Other Construction [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		3,202
Balance at end of period			3,202
Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		84,277	79,290
Loans charged-off			(14,481)
Recoveries			8,671
Provision for credit losses (PCL)			10,797
Balance at end of period			84,277	79,290
Allowance for Loan Losses, LHFI [Member] | Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		25,992	27,359
Loans charged-off			(5,344)
Recoveries			1,257
Provision for credit losses (PCL)			2,720
Balance at end of period			25,992	27,359
Allowance for Loan Losses, LHFI [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		3,379	2,890
Loans charged-off			(2,278)
Recoveries			1,829
Provision for credit losses (PCL)			938
Balance at end of period			3,379	2,890
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		2,229	990
Provision for credit losses (PCL)			1,239
Balance at end of period			2,229	990
Allowance for Loan Losses, LHFI [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		5,303	6,194
Loans charged-off			(5,966)
Recoveries			3,524
Provision for credit losses (PCL)			1,551
Balance at end of period			5,303	6,194
Allowance for Loan Losses, LHFI [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Commercial LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		8,260	7,390
Loans charged-off			(40)
Recoveries			894
Provision for credit losses (PCL)			16
Balance at end of period			8,260	7,390
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 Losses [Roll Forward]
Balance at beginning of period		8,932	8,641
Loans charged-off			(531)
Recoveries			666
Provision for credit losses (PCL)			156
Balance at end of period			8,932	8,641
Allowance for Loan Losses, LHFI [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		26,158	22,376
Loans charged-off			(322)
Recoveries			472
Provision for credit losses (PCL)			3,632
Balance at end of period			26,158	22,376
Allowance for Loan Losses, LHFI [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		$ 4,024	3,450
Recoveries			29
Provision for credit losses (PCL)			545
Balance at end of period			$ 4,024	$ 3,450
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.
[2]	The allowance for loan losses balance related to the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions, which were transferred from acquired impaired loans to LHFI during 2018.

Acquired Loans - Additional Inf

Acquired Loans - Additional Information (Details) - USD ($) $ in Thousands	Jan. 01, 2020	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Financing Receivable Allowance For Credit Losses [Line Items]
Acquired loans		$ 72,601
Allowance for loan losses, acquired loans		$ 815	[1]	$ 1,231	$ 4,079
ASU 2016-13 [Member] | Purchased Credit Deteriorated (PCD) Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Acquired loans	$ 72,600
Allowance for loan losses, acquired loans	$ 815
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.

Acquired Loans - Schedule of Ac

Acquired Loans - Schedule of Acquired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Financing Receivable Allowance For Credit Losses [Line Items]
Acquired loans	$ 72,601
Less allowance for loan losses, acquired loans	815	[1]	$ 1,231	$ 4,079
Net acquired loans	71,786
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Acquired loans	4,771
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Acquired loans	17,525
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Acquired loans	38,206
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Acquired loans	3,946
Commercial and Industrial Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Acquired loans	5,035
Consumer Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Acquired loans	520
Other Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Acquired loans	$ 2,598
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.

Acquired Loans - Changes in the

Acquired Loans - Changes in the Carrying Value of Acquired Loans (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		$ 71,786
Accretion to interest income			$ 5,532	$ 9,514
Carrying value, net, ending			71,786
Acquired Not ASC 310-30 [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning	[1]	0	2,811
Transfers	[1],[2]		(2,926)
Accretion to interest income	[1]		115
Payments received, net	[1]		0
Other	[1],[3]		0
Change in allowance for loan losses, acquired loans	[1]		0
Carrying value, net, ending	[1]	0	0	2,811
Acquired Not ASC 310-30 [Member] | ASU 2016-13 [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, ending	[1]	0
Acquired Impaired [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		$ 71,786	102,890
Accounting Standards Update Extensible List		us-gaap:AccountingStandardsUpdate201613Member
Transfers	[2]		0
Accretion to interest income			5,532
Payments received, net			(37,230)
Other	[3]		178
Change in allowance for loan losses, acquired loans			416
Carrying value, net, ending		$ 0	$ 71,786	$ 102,890
Acquired Impaired [Member] | ASU 2016-13 [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, ending		$ (71,786)
[1]	“Acquired Not ASC 310-30” loans consist of loans that are not in scope for FASB ASC Subtopic 310-30.
[2]	“Acquired Not ASC 310-30” loans transferred to LHFI due to the discount on these loans being fully amortized.
[3]	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, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in accretable difference on acquired loans [Abstract]
Accretable yield at beginning of period		$ (14,816)	$ (17,722)	$ (31,426)
FASB ASU 2016-13 adoption adjustment		14,816
Accretion to interest income			5,532	9,514
Disposals, net			2,072	3,926
Transfers	[1]	$ 0	0	5,874
Reclassification from nonaccretable difference	[2]		(4,698)	(5,610)
Accretable yield at end of period			$ (14,816)	$ (17,722)
[1]	During 2018, Trustmark transferred the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions from acquired impaired loans to LHFI.
[2]	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, 2020		Dec. 31, 2019		Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period		$ 815	[1]	$ 1,231		$ 4,079
FASB ASU 2016-13 adoption adjustment		(815)
Transfers	[2]	$ 0		0		(1,554)
Net (charge-offs) recoveries				(458)		(289)
Provision for loan losses, acquired loans	[1]			42		(1,005)
Balance at end of period				$ 815	[1]	$ 1,231
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.
[2]	The allowance for loan losses balance related to the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions, which were transferred from acquired impaired loans to LHFI during 2018.

Acquired Loans - Acquired Loans

Acquired Loans - Acquired Loans by Loan Class and Credit Quality Indicator (Details) $ in Thousands	Dec. 31, 2019USD ($)
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	$ 71,786
Acquired Loans, Aging [Abstract]
Current	70,305
Acquired Loans, Past Due	2,296
Nonaccrual	0	[1]
Total Acquired Loans	72,601
Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	1,307	[2]
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current	4,639
Acquired Loans, Past Due	132
Nonaccrual	0	[1]
Total Acquired Loans	4,771
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	38	[2]
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current	16,332
Acquired Loans, Past Due	1,193
Nonaccrual	0	[1]
Total Acquired Loans	17,525
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	366	[2]
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current	37,319
Acquired Loans, Past Due	887
Nonaccrual	0	[1]
Total Acquired Loans	38,206
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	851	[2]
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current	3,893
Acquired Loans, Past Due	53
Nonaccrual	0	[1]
Total Acquired Loans	3,946
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	52	[2]
Commercial and Industrial Loans [Member]
Acquired Loans, Aging [Abstract]
Current	5,035
Acquired Loans, Past Due	0
Nonaccrual	0	[1]
Total Acquired Loans	5,035
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0	[2]
Consumer Loans [Member]
Acquired Loans, Aging [Abstract]
Current	489
Acquired Loans, Past Due	31
Nonaccrual	0	[1]
Total Acquired Loans	520
Consumer Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0	[2]
Other Loans [Member]
Acquired Loans, Aging [Abstract]
Current	2,598
Acquired Loans, Past Due	0
Nonaccrual	0	[1]
Total Acquired Loans	2,598
Other Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0	[2]
Commercial LHFI [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	57,785
Commercial LHFI [Member] | Pass Categories 1-6 [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	44,922
Commercial LHFI [Member] | Special Mention Category 7 [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	42
Commercial LHFI [Member] | Substandard Category 8 [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	10,819
Commercial LHFI [Member] | Doubtful Category 9 [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	2,002
Commercial LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	4,214
Commercial LHFI [Member] | Construction, Land Development and Other Land [Member] | Pass Categories 1-6 [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	4,022
Commercial LHFI [Member] | Construction, Land Development and Other Land [Member] | Substandard Category 8 [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	192
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	3,786
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Pass Categories 1-6 [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	3,164
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Special Mention Category 7 [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	42
Commercial LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Substandard Category 8 [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	580
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	38,206
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Pass Categories 1-6 [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	27,848
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Substandard Category 8 [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	9,972
Commercial LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Doubtful Category 9 [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	386
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	3,946
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Pass Categories 1-6 [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	3,878
Commercial LHFI [Member] | Other Real Estate Secured [Member] | Substandard Category 8 [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	68
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	5,035
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Pass Categories 1-6 [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	3,419
Commercial LHFI [Member] | Commercial and Industrial Loans [Member] | Doubtful Category 9 [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	1,616
Commercial LHFI [Member] | Other Loans [Member] | Commercial Loan [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	2,598
Commercial LHFI [Member] | Other Loans [Member] | Pass Categories 1-6 [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	2,591
Commercial LHFI [Member] | Other Loans [Member] | Substandard Category 8 [Member]
Acquired Loans, Commercial Loans [Abstract]
Acquired loans	7
Consumer LHFI [Member]
Acquired Loans, Aging [Abstract]
Current	13,795
Subtotal	14,816
Total Acquired Loans	72,601
Consumer LHFI [Member] | Past Due 30-89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	740
Consumer LHFI [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	281
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current	463
Subtotal	557
Total Acquired Loans	4,771
Consumer LHFI [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 30-89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	94
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Current	12,843
Subtotal	13,739
Total Acquired Loans	17,525
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30-89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	615
Consumer LHFI [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	281
Consumer LHFI [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Total Acquired Loans	38,206
Consumer LHFI [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Total Acquired Loans	3,946
Consumer LHFI [Member] | Commercial and Industrial Loans [Member]
Acquired Loans, Aging [Abstract]
Total Acquired Loans	5,035
Consumer LHFI [Member] | Consumer Loans [Member]
Acquired Loans, Aging [Abstract]
Current	489
Subtotal	520
Total Acquired Loans	520
Consumer LHFI [Member] | Consumer Loans [Member] | Past Due 30-89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	31
Consumer LHFI [Member] | Other Loans [Member]
Acquired Loans, Aging [Abstract]
Total Acquired Loans	$ 2,598
[1]	Acquired loans not accounted for under FASB ASC Subtopic 310-30.
[2]	Past due 90 days or more but still accruing interest.

Acquired Loans - Aging Analysis

Acquired Loans - Aging Analysis of Past Due and Nonaccrual Acquired Loans (Details) $ in Thousands	Dec. 31, 2019USD ($)
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	$ 2,296
Nonaccrual	0	[1]
Current	70,305
Acquired Loans	72,601
Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	843
Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	146
Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	1,307	[2]
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	132
Nonaccrual	0	[1]
Current	4,639
Acquired Loans	4,771
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	94
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
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	38	[2]
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	1,193
Nonaccrual	0	[1]
Current	16,332
Acquired Loans	17,525
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	696
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	131
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	366	[2]
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	887
Nonaccrual	0	[1]
Current	37,319
Acquired Loans	38,206
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	36
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
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	851	[2]
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	53
Nonaccrual	0	[1]
Current	3,893
Acquired Loans	3,946
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	1
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0
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	52	[2]
Commercial and Industrial Loans [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0
Nonaccrual	0	[1]
Current	5,035
Acquired Loans	5,035
Commercial and Industrial Loans [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0
Commercial and Industrial Loans [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0	[2]
Consumer Loans [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	31
Nonaccrual	0	[1]
Current	489
Acquired Loans	520
Consumer Loans [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	16
Consumer Loans [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	15
Consumer Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0	[2]
Other Loans [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0
Nonaccrual	0	[1]
Current	2,598
Acquired Loans	2,598
Other Loans [Member] | Past Due 30 to 59 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0
Other Loans [Member] | Past Due 60 to 89 Days [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	0
Other Loans [Member] | Past Due 90 Days or More [Member]
Acquired Loans, Aging [Abstract]
Acquired Loans, Past Due	$ 0	[2]
[1]	Acquired loans not accounted for under FASB ASC Subtopic 310-30.
[2]	Past due 90 days or more but still accruing interest.

Premises and Equipment, Net - P

Premises and Equipment, Net - Premises and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	$ 449,815	$ 437,073
Less accumulated depreciation and amortization	263,147	256,608
Premises and equipment, net	186,668	180,465
Finance lease right-of-use assets	7,471	9,326
Assets held for sale	139	0
Total premises and equipment, net	194,278	189,791
Land [Member]
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	52,189	52,454
Building and Leasehold Improvements [Member]
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	216,650	210,362
Furniture and Equipment [Member]
Premises and Equipment, Net, by Type [Abstract]
Total cost of premises and equipment	$ 180,976	$ 174,257

Premises and Equipment, Net - A

Premises and Equipment, Net - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)Property	Dec. 31, 2019USD ($)Property	Dec. 31, 2018USD ($)
Property Plant And Equipment [Abstract]
Number of property held for sale | Property	1	0
Property valuation adjustments	$ 1,700	$ 0	$ 173
Premises and Equipment, Net, by Type [Abstract]
Depreciation and amortization of premises and equipment	$ 14,800	$ 15,700	$ 15,700

Mortgage Banking - Schedule of

Mortgage Banking - Schedule of Activity in the Mortgage Servicing Rights (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Mortgage servicing rights [Abstract]
Balance at beginning of period	$ 79,394	$ 95,596
Origination of servicing assets	29,805	16,711
Change in fair value [Abstract]
Due to market changes	(26,147)	(21,078)
Due to runoff	(16,588)	(11,835)
Balance at end of period	$ 66,464	$ 79,394

Mortgage Banking - Additional I

Mortgage Banking - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)CPR	Dec. 31, 2019USD ($)CPR	Dec. 31, 2018USD ($)
Schedule of changes in the reserve for mortgage loan [Abstract]
Assumed average prepayment speed | CPR	15	11
Average discount rate (in hundredths)	9.53%	10.03%
Annual servicing fee	$ 23,300	$ 22,600	$ 21,900
Servicing fee income percentage of outstanding balance of underlying loans (in hundredths)	0.31%
Mortgage servicing rights [Abstract]
Residential mortgage loans sold	$ 2,532,000	1,404,000	1,092,000
Gains on sales of residential mortgage loans	$ 110,900	30,300	$ 21,800
Period of putback response	60 days
Reserve for mortgage loan servicing putback expenses	$ 500	$ 500

Mortgage Banking - Schedule o_2

Mortgage Banking - Schedule of Mortgage Loans Sold and Serviced for Others (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	$ 7,657,090	$ 7,157,234
Federal National Mortgage Association [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	4,629,670	4,411,914
Government National Mortgage Association [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	2,960,760	2,652,782
Federal Home Loan Mortgage Corporation [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	50,459	73,134
Other [Member]
Mortgage Loans On Real Estate [Line Items]
Total mortgage loans sold and serviced for others	$ 16,201	$ 19,404

Goodwill and Identifiable Int_3

Goodwill and Identifiable Intangible Assets - Goodwill by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 379,627	$ 379,627
Adjustment	5,643	0
Balance, end of period	385,270	379,627
General Banking [Member]
Goodwill [Roll Forward]
Goodwill, beginning of period	334,603	334,603
Adjustment	0	0
Balance, end of period	334,603	334,603
Insurance [Member]
Goodwill [Roll Forward]
Goodwill, beginning of period	45,024	45,024
Adjustment	5,643	0
Balance, end of period	$ 50,667	$ 45,024

Goodwill and Identifiable Int_4

Goodwill and Identifiable Intangible Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Amortization expense of identifiable intangible assets	$ 3,100,000	$ 4,100,000	$ 5,200,000
Impairment losses on identifiable intangible assets	0	0	0
Future amortization expense for identifiable intangible assets [Abstract]
2021	2,300,000
2022	1,400,000
2023	673,000
2024	471,000
2025	403,000
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, 2020	Dec. 31, 2019
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 106,271	$ 103,170
Accumulated Amortization	98,881	95,827
Net Carrying Amount	$ 7,390	7,343
Remaining Weighted-Average Amortization Periods in Years	10 years 9 months 18 days
Core Deposit Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 87,674	87,674
Accumulated Amortization	84,580	82,096
Net Carrying Amount	$ 3,094	5,578
Remaining Weighted-Average Amortization Periods in Years	3 years 1 month 6 days
Insurance Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 17,272	14,171
Accumulated Amortization	13,159	12,655
Net Carrying Amount	$ 4,113	1,516
Remaining Weighted-Average Amortization Periods in Years	17 years
Banking Charters [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,325	1,325
Accumulated Amortization	1,142	1,076
Net Carrying Amount	$ 183	$ 249
Remaining Weighted-Average Amortization Periods in Years	2 years 8 months 12 days

Other Real Estate - Changes and

Other Real Estate - Changes and Gains (Losses), Net on Other Real Estate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation Of Carrying Amount Of Real Estate Investments Roll Forward
Balance at beginning of period	$ 29,248	$ 34,668	$ 43,228
Additions	635	8,598	12,115
Disposals	(16,446)	(11,474)	(19,802)
Write-downs	(1,786)	(2,544)	(873)
Balance at end of period	11,651	29,248	34,668
Gains (losses), net on the sale of other real estate included in other real estate expense	$ 897	$ (291)	$ 700

Other Real Estate - Other Real

Other Real Estate - Other Real Estate, By Type of Property (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other real estate [Line Items]
Total other real estate	$ 11,651	$ 29,248	$ 34,668	$ 43,228
Construction, Land Development And Other Land Properties [Member]
Other real estate [Line Items]
Total other real estate	3,857	11,482
1 - 4 Family Residential Properties [Member]
Other real estate [Line Items]
Total other real estate	1,349	3,453
Nonfarm, Nonresidential Properties [Member]
Other real estate [Line Items]
Total other real estate	$ 6,445	$ 14,313

Other Real Estate - Other Rea_2

Other Real Estate - Other Real Estate, By Geographic Location (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other real estate [Line Items]
Total other real estate		$ 11,651	$ 29,248	$ 34,668	$ 43,228
Alabama [Member]
Other real estate [Line Items]
Total other real estate		3,271	8,133
Florida [Member]
Other real estate [Line Items]
Total other real estate			5,877
Mississippi [Member]
Other real estate [Line Items]
Total other real estate	[1]	8,330	14,919
Tennessee [Member]
Other real estate [Line Items]
Total other real estate	[2]	$ 50	$ 319
[1]	Mississippi includes Central and Southern Mississippi Regions.
[2]	Tennessee includes Memphis, Tennessee and Northern Mississippi Regions.

Other Real Estate - Additional

Other Real Estate - Additional information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Reconciliation Of Carrying Amount Of Real Estate Investments Roll Forward
Foreclosed residential real estate properties recorded as a result of obtaining physical possession of property	$ 1,300	$ 3,500
Consumer mortgage loans and that formal foreclosure proceedings are in process	$ 424	$ 953

Leases - Components of Net Leas

Leases - Components of Net Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finance leases
Amortization of right-of-use assets	$ 1,856	$ 2,162
Interest on lease liabilities	254	307
Operating lease cost	5,188	5,183
Short-term lease cost	423	370
Variable lease cost	1,286	1,387
Sublease income	(335)	(331)
Net lease cost	$ 8,672	$ 9,078

Leases - Cash Payments Included

Leases - Cash Payments Included in Measurement of Lease liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finance leases
Operating cash flows included in operating activities	$ 254	$ 307
Financing cash flows included in payments under finance lease obligations	1,715	1,964
Operating leases
Operating cash flows (fixed payments) included in other operating activities, net	4,988	5,092
Operating cash flows (liability reduction) included in other operating activities, net	$ 3,856	$ 5,404

Leases - Balance Sheet Informat

Leases - Balance Sheet Information and Weighted-Average Lease Terms and Discount Rates Related to Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Finance lease right-of-use assets, net of accumulated depreciation	$ 7,471	$ 9,326
Finance lease liabilities	7,805	9,520
Operating lease right-of-use assets	30,901	31,182
Operating lease liabilities	$ 32,290	$ 32,354
Weighted-average lease term
Finance leases	8 years 6 months 10 days	8 years 7 months 13 days
Operating leases	8 years 7 months 24 days	9 years 18 days
Weighted-average discount rate
Finance leases	3.10%	3.01%
Operating leases	3.41%	3.51%

Leases - Future Minimum Rental

Leases - Future Minimum Rental Commitments Under Finance and Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Finance leases, 2021	$ 1,615
Finance leases, 2022	1,556
Finance leases, 2023	871
Finance leases, 2024	572
Finance leases, 2025	584
Thereafter	3,868
Finance leases, total minimum lease payments	9,066
Finance leases, imputed interest	(1,261)
Finance lease liabilities	7,805	$ 9,520
Operating leases, 2021	4,714
Operating leases, 2022	4,456
Operating leases, 2023	4,342
Operating leases, 2024	4,449
Operating leases, 2025	4,464
Thereafter	15,040
Operating leases, total minimum lease payments	37,465
Operating leases, imputed interest	(5,175)
Operating lease liabilities	$ 32,290	$ 32,354

Deposits - Deposits Summary (De

Deposits - Deposits Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deposits [Abstract]
Noninterest-bearing demand	$ 4,349,010	$ 2,891,215
Interest-bearing demand	3,646,246	3,125,914
Savings	4,647,610	3,590,509
Time	1,405,898	1,637,919
Total deposits	$ 14,048,764	$ 11,245,557

Deposits - Interest Expense on

Deposits - Interest Expense on Deposits by Type (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest expense on deposits by type [Abstract]
Interest-bearing demand	$ 9,985	$ 35,428	$ 18,479
Savings	13,481	19,462	17,980
Time	14,021	24,281	17,477
Total	$ 37,487	$ 79,171	$ 53,936

Deposits - Additional Informati

Deposits - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deposits [Abstract]
Time deposits that exceed the FDIC insurance limit of $250 thousand	$ 228.1	$ 285.7

Deposits - Maturities of Intere

Deposits - Maturities of Interest-Bearing Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Maturities of interest-bearing deposits [Abstract]
2021	$ 1,152,489
2022	176,421
2023	46,750
2024	14,330
2025	12,738
Thereafter	3,170
Total time deposits	1,405,898	$ 1,637,919
Interest-bearing deposits with no stated maturity	8,293,856
Total interest-bearing deposits	$ 9,699,754	$ 8,354,342

Borrowings - Securities Sold Un

Borrowings - Securities Sold Under Repurchase Agreements - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Securities sold under repurchase agreements, secured by securities carrying amount	$ 156.1	$ 105.6

Borrowings - Schedule of Securi

Borrowings - Schedule of Securities Sold Under Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Securities sold under repurchase agreements by collateral pledged
Total securities sold under repurchase agreements	$ 128,053	$ 53,572
Residential Mortgage Pass-Through Securities Issued by FNMA and FHLMC [Member]
Securities sold under repurchase agreements by collateral pledged
Total securities sold under repurchase agreements	115,357
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	$ 12,696	24,282
Commercial Mortgage-Backed Securities Issued or Guaranteed by FNMA, FHLMC or GNMA [Member]
Securities sold under repurchase agreements by collateral pledged
Total securities sold under repurchase agreements		$ 29,290

Borrowings - Summary of Other B

Borrowings - Summary of Other Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
FHLB advances	$ 741	$ 811
Serviced GNMA loans eligible for repurchase	141,160	57,062
Finance lease liabilities	7,805	9,520
Other	18,546	18,003
Total other borrowings	$ 168,252	$ 85,396

Borrowings - FHLB Advances - Ad

Borrowings - FHLB Advances - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020USD ($)Loan	Dec. 31, 2019USD ($)Loan	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Interest expense, short-term borrowings	$ 9,000	$ 0	$ 4,400,000
Federal Home Loan Bank Advances
Debt Instrument [Line Items]
Interest expense, long-term	$ 8,000	$ 5,000	$ 6,000
Atlanta | BancTrust [Member] | Federal Home Loan Bank Advances
Debt Instrument [Line Items]
Interest rate (in hundredths)	0.08%
Debt instrument remaining maturity period	5 years 8 months 15 days	2 years 4 months 13 days
Number of outstanding long-term FHLB advances | Loan	1	2
Long-term FHLB advances	$ 116,000	$ 811,000
Weighted-average cost related to FHLB advances (in hundredths)		0.64%
Atlanta | BancTrust [Member] | Federal Home Loan Bank Advances | FHLB Advances at 0.08% [Member]
Debt Instrument [Line Items]
Interest rate (in hundredths)		0.08%
Long-term FHLB advances		$ 135,000
Atlanta | BancTrust [Member] | Federal Home Loan Bank Advances | FHLB Advances at 0.75% [Member]
Debt Instrument [Line Items]
Interest rate (in hundredths)		0.75%
Long-term FHLB advances		$ 676,000
Atlanta | BancTrust [Member] | Federal Home Loan Bank Advances | Fair Market Value Adjustment [Member]
Debt Instrument [Line Items]
Fair value adjustment on FHLB advances	$ 0	$ 0
Atlanta | Federal Home Loan Bank Advances
Debt Instrument [Line Items]
Number of outstanding short-term FHLB advances | Loan		0
Atlanta | Federal Home Loan Bank Advances | BancTrust [Member]
Debt Instrument [Line Items]
Number of outstanding short-term FHLB advances | Loan	1
Short-term FHLB advances	$ 625,000
Interest rate (in hundredths)	0.75%
Debt instrument remaining maturity period	181 days
Dallas [Member] | Federal Home Loan Bank Advances
Debt Instrument [Line Items]
Number of outstanding long-term FHLB advances | Loan	0	0
Additional debt instrument borrowing capacity	$ 2,725,000,000	$ 3,178,000,000

Borrowings - Subordinated Notes

Borrowings - Subordinated Notes Payable - Additional Information (Details) - USD ($) $ in Thousands	Dec. 01, 2025	Dec. 31, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Subordinated notes		$ 122,921	$ 122,921
Subordinated Notes [Member]
Debt Instrument [Line Items]
Face amount of debt issued		$ 125,000	$ 125,000
Interest rate (in hundredths)		3.625%	3.625%
Maturity date			Dec. 1, 2030
Underwriting discount percentage		1.20%
Offering expenses		$ 600
Proceeds from issuance of subordinated notes before deducting offering expenses		123,500
Subordinated notes		$ 122,900	$ 122,900
Frequency of periodic payment			semi-annually
Subordinated Notes [Member] | Forecast
Debt Instrument [Line Items]
Frequency of periodic payment	quarterly
Variable interest rate, description	Three-Month Term Secured Overnight Financing Rate (SOFR)
Basis spread percentage (in hundredths)	3.387%

Borrowings - Junior Subordinate

Borrowings - Junior Subordinated Debt Securities - Additional information (Details) $ in Thousands	Aug. 18, 2006USD ($)Quarter	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Variable Interest Entity [Line Items]
Junior subordinated debt securities		$ 61,856	$ 61,856
Total assets		16,551,840	13,497,877	$ 13,286,460
Total liabilities and shareholders' equity		16,551,840	13,497,877
Common securities		13,215	13,376
Net income		160,025	$ 150,460	149,584
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		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		51	79	74
Dividends paid		$ 51	$ 79	$ 74

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, 2020	Dec. 31, 2019	[1]	Dec. 31, 2018	[1]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		$ 32,289	$ 42,603		$ 43,702
Bank card and other fees		31,022	31,736		28,905
Mortgage banking, net		125,822	29,822		34,674
Insurance commissions		45,176	42,396		40,481
Wealth management		31,625	30,679		30,338
Other, net		8,659	9,809		6,736
Total Noninterest Income		274,593	187,045		184,836
Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		32,289	42,603		43,702
Bank card and other fees		27,428	28,030		27,008
Insurance commissions		45,176	42,396		40,481
Wealth management		31,625	30,679		30,338
Other, net		7,631	9,867		6,836
Total Noninterest Income		144,149	153,575		148,365
Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees	[2]	3,594	3,706		1,897
Mortgage banking, net	[2]	125,822	29,822		34,674
Other, net	[2]	1,028	(58)		(100)
Total Noninterest Income	[2]	130,444	33,470		36,471
General Banking Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		32,213	42,509		43,614
Bank card and other fees		30,992	31,679		28,801
Mortgage banking, net		125,822	29,822		34,674
Wealth management		254	379		296
Other, net		8,410	9,367		6,545
Total Noninterest Income		197,691	113,756		113,930
General Banking Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		32,213	42,509		43,614
Bank card and other fees		27,398	27,973		26,904
Wealth management		254	379		296
Other, net		7,432	9,528		6,762
Total Noninterest Income		67,297	80,389		77,576
General Banking Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees	[2]	3,594	3,706		1,897
Mortgage banking, net	[2]	125,822	29,822		34,674
Other, net	[2]	978	(161)		(217)
Total Noninterest Income	[2]	130,394	33,367		36,354
Wealth Management Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		76	94		88
Bank card and other fees		30	57		104
Wealth management		31,371	30,300		30,042
Other, net		157	409		186
Total Noninterest Income		31,634	30,860		30,420
Wealth Management Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		76	94		88
Bank card and other fees		30	57		104
Wealth management		31,371	30,300		30,042
Other, net		107	306		69
Total Noninterest Income		31,584	30,757		30,303
Wealth Management Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Other, net	[2]	50	103		117
Total Noninterest Income	[2]	50	103		117
Insurance Segment [Member]
Revenue From Contract With Customer [Line Items]
Insurance commissions		45,176	42,396		40,481
Other, net		92	33		5
Total Noninterest Income		45,268	42,429		40,486
Insurance Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Insurance commissions		45,176	42,396		40,481
Other, net		92	33		5
Total Noninterest Income		$ 45,268	$ 42,429		$ 40,486
[1]	During the first quarter of 2020, Trustmark revised the composition of its operating segments by moving the Retail Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes.  The prior period amounts presented include reclassifications to conform to the current period presentation.
[2]	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, 2020	Dec. 31, 2019	Dec. 31, 2018
Current [Abstract]
Federal	$ 40,118	$ 20,068	$ 4,532
State	9,439	7,145	5,997
Deferred [Abstract]
Federal	(15,840)	(3,104)	9,392
State	(3,960)	(776)	2,348
Income tax provision	$ 29,757	$ 23,333	$ 22,269

Income Taxes - Income Tax Recon

Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of provision for tax from the federal rate to the effective tax rate [Abstract]
Income tax computed at statutory tax rate	$ 39,854	$ 36,497	$ 36,089
Tax exempt interest	(4,284)	(4,951)	(4,533)
Nondeductible interest expense	247	564	416
State income taxes, net	7,457	5,645	4,738
Income tax credits, net	(9,375)	(13,473)	(15,404)
Death benefit gains	(91)	(123)	(268)
Other	(4,051)	(826)	1,231
Income tax provision	$ 29,757	$ 23,333	$ 22,269

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets [Abstract]
Loan purchase accounting	$ 293	$ 845
Other real estate	2,049	5,845
Accumulated credit losses	39,073	21,774
Deferred compensation	17,465	16,498
Finance and operating lease liabilities	10,024	10,469
Realized built-in losses	10,681	11,431
Securities	2,233	3,028
Pension and other postretirement benefit plans	6,128	5,194
Interest on nonaccrual loans	1,034	942
Loans held for sale	2,754	481
Stock-based compensation	2,749	2,527
Loan fees	3,401
Other	10,294	8,309
Gross deferred tax asset	108,178	87,343
Deferred tax liabilities [Abstract]
Goodwill and other identifiable intangibles	15,136	15,336
Premises and equipment	11,479	11,913
Finance and operating lease right-of-use assets	9,593	10,127
Mortgage servicing rights	7,108	11,002
Securities	9,712	2,115
Other	4,537	5,192
Gross deferred tax liability	57,565	55,685
Net deferred tax asset	$ 50,613	$ 31,658

Income Taxes - Changes in Unrec

Income Taxes - Changes in Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in unrecognized tax benefits [Roll Forward]
Balance at beginning of period	$ 1,524	$ 1,249	$ 1,105
Change due to tax positions taken during the current year	353	279	282
Change due to tax positions taken during a prior year	79	134	56
Change due to the lapse of applicable statute of limitations during the current year	(175)	(138)	(194)
Change due to settlements with taxing authorities during the current year	0	0	0
Balance at end of period	1,781	1,524	1,249
Accrued interest, net of federal benefit, at end of period	330	271	212
Unrecognized tax benefits that would impact the effective tax rate, if recognized, at end of period	$ 1,420	$ 1,218	$ 988

Defined Benefit and Other Pos_3

Defined Benefit and Other Postretirement Benefits - Plan Benefit Obligation, Plan Assets and Funded Status of the Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Trustmark Capital Accumulation Plan [Member] | Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member]
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year	$ 9,060	$ 9,179
Service cost	254	211	$ 277
Interest cost	241	361	332
Actuarial (gain) loss	876	875
Benefits paid	(884)	(1,566)
Benefit obligation, end of year	9,547	9,060	9,179
Change in plan assets [ Roll Forward]
Fair value of plan assets, beginning of year	3,443	3,954
Actual return on plan assets	(87)	668
Employer contributions	401	387
Benefit payments	(884)	(1,566)
Fair value of plan assets, end of year	2,873	3,443	3,954
Funded status at end of year - net liability	(6,674)	(5,617)
Amounts recognized in accumulated other comprehensive income (loss) [Abstract]
Net loss	2,564	1,893
Supplemental Retirement Plan [Member]
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year	57,482	53,257
Service cost	77	109	116
Interest cost	1,576	2,044	1,865
Actuarial (gain) loss	4,168	5,498
Benefits paid	(3,657)	(3,426)
Benefit obligation, end of year	59,646	57,482	53,257
Change in plan assets [ Roll Forward]
Fair value of plan assets, beginning of year	0	0
Employer contributions	3,657	3,426
Benefit payments	(3,657)	(3,426)
Fair value of plan assets, end of year	0	0	$ 0
Funded status at end of year - net liability	(59,646)	(57,482)
Amounts recognized in accumulated other comprehensive income (loss) [Abstract]
Net loss	21,486	18,275
Prior service cost	459	609
Amounts recognized	$ 21,945	$ 18,884

Defined Benefit and Other Pos_4

Defined Benefit and Other Postretirement Benefits - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Trustmark Capital Accumulation Plan [Member] | Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member]
Net periodic benefit cost [Abstract]
Service cost	$ 254	$ 211	$ 277
Interest cost	241	361	332
Expected return on plan assets	(154)	(202)	(227)
Recognized net loss due to lump sum settlements	119	312	161
Recognized net actuarial loss	326	373	571
Net periodic benefit cost	786	1,055	1,114
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)	671	(277)	(1,017)
Total recognized in net periodic benefit cost and other comprehensive income (loss)	$ 1,457	$ 778	$ 97
Weighted-average assumptions as of end of year [Abstract]
Discount rate for benefit obligation (in hundredths)	1.95%	2.84%	3.97%
Discount rate for net periodic benefit cost (in hundredths)	2.84%	3.97%	3.32%
Expected long-term return on plan assets (in hundredths)	5.00%	5.00%	5.00%
Supplemental Retirement Plan [Member]
Net periodic benefit cost [Abstract]
Service cost	$ 77	$ 109	$ 116
Interest cost	1,576	2,044	1,865
Amortization of prior service credits	150	250	250
Recognized net actuarial loss	957	627	884
Net periodic benefit cost	2,760	3,030	3,115
Other changes in plan assets and benefit obligation recognized in other comprehensive income (loss), before taxes:
Net loss (gain)	3,211	4,872	(4,111)
Amortization of prior service cost	(150)	(250)	(250)
Net (gain) loss - Total recognized in other comprehensive income (loss)	3,061	4,622	(4,361)
Total recognized in net periodic benefit cost and other comprehensive income (loss)	$ 5,821	$ 7,652	$ (1,246)
Weighted-average assumptions as of end of year [Abstract]
Discount rate for benefit obligation (in hundredths)	1.95%	2.84%	3.97%
Discount rate for net periodic benefit cost (in hundredths)	2.84%	3.97%	3.32%

Defined Benefit and Other Pos_5

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, 2020	Dec. 31, 2019
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)	5.00%	2.00%
Exchange Traded Equity Securities Funds [Member]
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	43.00%	46.00%
Exchange Traded Fixed Income Funds [Member]
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	41.00%	41.00%
International Exchange Traded Funds [Member]
Asset target allocations [Abstract]
Weighted-average asset allocation (in hundredths)	11.00%	11.00%

Defined Benefit and Other Pos_6

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Asset target allocations [Abstract]
Fair value of plan assets	$ 2,873	$ 3,443	$ 3,954
Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	2,873	3,443
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	131	51
Money Market Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	131	51
Money Market Funds [Member] | Level 2 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
Money Market Funds [Member] | Level 3 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	0	0
Exchange Traded Equity Securities Funds [Member]
Asset target allocations [Abstract]
Fair value of plan assets	1,242	1,592
Exchange Traded Equity Securities Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	1,242	1,592
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	318	383
International Exchange Traded Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	318	383
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	1,182	1,417
Exchange Traded Fixed Income Funds [Member] | Level 1 [Member]
Asset target allocations [Abstract]
Fair value of plan assets	1,182	1,417
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_7

Defined Benefit and Other Postretirement Benefits - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Trustmark Capital Accumulation Plan [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		$ 306
Trustmark's contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions		563
Trustmark Capital Accumulation Plan [Member] | Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member]
Estimated future benefit payments [Abstract]
Accumulated other comprehensive loss expected to be recognized during next fiscal year as components of net periodic benefit cost		(594)
Trustmark Capital Accumulation Plan [Member] | Forecast
Defined Benefit Plan Disclosure [Line Items]
Trustmark's minimum required contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions	$ 327
Trustmark's excess of minimum required contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions	$ 257
Supplemental Retirement Plan [Member]
Estimated future benefit payments [Abstract]
Accumulated other comprehensive loss expected to be recognized during next fiscal year as components of net periodic benefit cost		(1,200)
Accumulated other comprehensive loss expected to be recognized during next fiscal year as prior service cost		112
Defined Contribution Plan [Member]
Other Benefit Plans - Defined Contribution Plan [Abstract]
Trustmarks contribution to defined contribution plan		$ 9,200	$ 8,200	$ 7,900
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_8

Defined Benefit and Other Postretirement Benefits - Estimated Future Benefit Payments and Other Disclosures (Details) $ in Thousands	Dec. 31, 2020USD ($)
Supplemental Retirement Plan [Member]
Estimated future benefit payments [Abstract]
2021	$ 3,893
2022	4,168
2023	4,033
2024	4,106
2025	3,774
2026 - 2030	17,296
Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member] | Trustmark Capital Accumulation Plan [Member]
Estimated future benefit payments [Abstract]
2021	1,437
2022	997
2023	1,466
2024	1,162
2025	569
2026 - 2030	$ 2,511

Stock and Incentive Compensat_3

Stock and Incentive Compensation Plans - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020shares
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-based 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)	771,055

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Performance Based Award [Member]
Shares [Roll Forward]
Nonvested shares, beginning of year (in shares)	149,914	177,695	213,516
Granted (in shares)	53,450	50,862	51,174
Released from restriction (in shares)	(36,357)	(61,347)	(55,351)
Forfeited (in shares)	(21,965)	(17,296)	(31,644)
Nonvested shares, end of year (in shares)	145,042	149,914	177,695
Weighted-Average Grant Date Fair Value [Abstract]
Nonvested shares, beginning of year (in dollars per share)	$ 32.88	$ 27.10	$ 25.37
Granted (in dollars per share)	31.98	33.44	31.88
Released from restriction (in dollars per share)	33.31	20.18	25.32
Forfeited (in dollars per share)	32.97	20.18	26.26
Nonvested shares, end of year (in dollars per share)	$ 32.43	$ 32.88	$ 27.10
Time-based Awards [Member]
Shares [Roll Forward]
Nonvested shares, beginning of year (in shares)	300,006	321,870	320,357
Granted (in shares)	123,810	113,673	118,325
Released from restriction (in shares)	(110,537)	(124,598)	(107,180)
Forfeited (in shares)	(11,660)	(10,939)	(9,632)
Nonvested shares, end of year (in shares)	301,619	300,006	321,870
Weighted-Average Grant Date Fair Value [Abstract]
Nonvested shares, beginning of year (in dollars per share)	$ 33.04	$ 28.48	$ 25.40
Granted (in dollars per share)	31.52	33.42	31.96
Released from restriction (in dollars per share)	33.58	21.64	23.02
Forfeited (in dollars per share)	32.47	32.73	29.30
Nonvested shares, end of year (in dollars per share)	$ 32.24	$ 33.04	$ 28.48

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Compensation expense [Abstract]
Recognized compensation expense	$ 5,197	$ 4,787	$ 3,870
Unrecognized compensation expense	4,704
Performance Based Award [Member]
Compensation expense [Abstract]
Recognized compensation expense	815	1,524	861
Unrecognized compensation expense	$ 1,836
Weighted average life of unrecognized compensation expense	1 year 6 months 25 days
Time-based Awards [Member]
Compensation expense [Abstract]
Recognized compensation expense	$ 4,382	$ 3,263	$ 3,009
Unrecognized compensation expense	$ 2,868
Weighted average life of unrecognized compensation expense	1 year 6 months 14 days

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Unused commitments to extend credit	$ 4,867	$ 4,349
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Potential exposure to credit loss in the event of nonperformance	$ 113.8	105.2
Letters of credit, maturity term - maximum	3 years
Collateral held, fair value	$ 21.9	$ 26.3

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Changes in ACL on Off-balance Sheet Credit Exposures (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Commitments And Contingencies Disclosure [Abstract]
Balance at beginning of period	$ 0	[1]
FASB ASU 2016-13 adoption adjustment	29,638
Credit loss expense related to off-balance sheet credit exposures	8,934	[1]
Balance at end of period	$ 38,572	[1]
[1]	Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach.  Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 01, 2020	Apr. 01, 2019	Mar. 11, 2016
Stockholders Equity [Line items]
Capital conservation buffer rate		2.50%	2.50%
Dividend potential for next fiscal year		$ 86,700
Period for which retained net income considered for approval		2 years
Stock Repurchase Program 1 [Member] | Common Stock [Member]
Stockholders Equity [Line items]
Amount of stock authorized for repurchase							$ 100,000
Repurchase shares of common stock		1,200,000	2,000,000	0
Repurchase shares of common stock, value		$ 36,900	$ 62,400
2016 Program [Member]
Stockholders Equity [Line items]
Repurchase shares of common stock		3,200,000
Repurchase shares of common stock, value		$ 100,000
Stock Repurchase Program 2 [Member]
Stockholders Equity [Line items]
Amount of stock authorized for repurchase						$ 100,000
Stock Repurchase Program 2 [Member] | Common Stock [Member]
Stockholders Equity [Line items]
Repurchase shares of common stock		887,000	601,000
Repurchase shares of common stock, value		$ 27,500	$ 19,700
2019 Program | Common Stock [Member]
Stockholders Equity [Line items]
Repurchase shares of common stock		1,500,000
Repurchase shares of common stock, value		$ 47,200
Stock Repurchase Program 3 [Member]
Stockholders Equity [Line items]
Amount of stock authorized for repurchase					$ 100,000
Stock Repurchase Program 3 [Member] | Subsequent Event
Stockholders Equity [Line items]
Repurchase shares of common stock	16,000
Repurchase shares of common stock, value	$ 446

Shareholders' Equity - Table of

Shareholders' Equity - Table of Actual Regulatory Capital Amounts and Ratios (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
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		$ 1,395,844	$ 1,312,668
Actual Regulatory Capital Ratio		11.62%	11.93%
Minimum Regulatory Capital Required Ratio		7.00%	7.00%
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		$ 1,455,844	$ 1,372,668
Actual Regulatory Capital Ratio		12.11	12.48
Minimum Regulatory Capital Required Ratio		8.500	8.500
Trustmark Corporation [Member] | Total Capital (to Risk Weighted Assets) [Member]
Total Capital (to Risk Weighted Assets) [Abstract]
Actual Regulatory Capital Amount		$ 1,696,794	$ 1,457,760
Actual Regulatory Capital Ratio		14.12	13.25
Minimum Regulatory Capital Required Ratio		10.500	10.500
Trustmark Corporation [Member] | Tier 1 Leverage (to Average Assets) [Member]
Tier 1 Leverage (to Average Assets) [Abstract]
Actual Regulatory Capital Amount		$ 1,455,844	$ 1,372,668
Actual Regulatory Capital Ratio		9.33	10.48
Minimum Regulatory Capital Required Ratio		4	4
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		$ 1,412,015	$ 1,352,893
Actual Regulatory Capital Ratio		11.75%	12.30%
Minimum Regulatory Capital Required Ratio		7.00%	7.00%
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		$ 1,412,015	$ 1,352,893
Actual Regulatory Capital Ratio		11.75	12.30
Minimum Regulatory Capital Required Ratio		8.500	8.500
Minimum Regulatory Provision to be Well-Capitalized Ratio		8	8
Trustmark National Bank [Member] | Total Capital (to Risk Weighted Assets) [Member]
Total Capital (to Risk Weighted Assets) [Abstract]
Actual Regulatory Capital Amount		$ 1,530,044	$ 1,437,985
Actual Regulatory Capital Ratio		12.73	13.07
Minimum Regulatory Capital Required Ratio		10.500	10.500
Minimum Regulatory Provision to be Well-Capitalized Ratio		10	10
Trustmark National Bank [Member] | Tier 1 Leverage (to Average Assets) [Member]
Tier 1 Leverage (to Average Assets) [Abstract]
Actual Regulatory Capital Amount		$ 1,412,015	$ 1,352,893
Actual Regulatory Capital Ratio		9.07	10.35
Minimum Regulatory Capital Required Ratio		4	4
Minimum Regulatory Provision to be Well-Capitalized Ratio		5	5
[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, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax amount	$ 30,068	$ 42,772	$ (9,907)
Other comprehensive income (loss), tax (expense) benefit	(7,519)	(10,693)	2,477
Other comprehensive income (loss), before reclassifications, net of tax amount	21,502	31,420	(8,416)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	1,047	659	986
Other comprehensive income (loss), net of tax amount	22,549	32,079	(7,430)
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	30,622	44,136	(19,221)
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, before tax amount	3,177	3,605	3,761
Other comprehensive income (loss), before tax amount	33,799	47,741	(15,460)
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	(7,657)	(11,033)	4,805
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, tax (expense) benefit	(794)	(901)	(940)
Other comprehensive income (loss), tax (expense) benefit	(8,451)	(11,934)	3,865
Other comprehensive income (loss), before reclassifications, net of tax amount	22,965	33,103	(14,416)
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, net of tax amount	2,383	2,704	2,821
Other comprehensive income (loss), net of tax amount	25,348	35,807	(11,595)
Change in Net Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(5,128)	(5,703)	3,742
Reclassification from accumulated other comprehensive income, current period, before tax amount	1,128	796	1,225
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	1,282	1,425	(936)
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(282)	(199)	(306)
Other comprehensive income (loss), before reclassifications, net of tax amount	(3,846)	(4,278)	2,806
Reclassification from accumulated other comprehensive income, current period, net of tax amount	846	597	919
Net Change in Prior Service Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	150	250	250
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(38)	(63)	(63)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	112	187	187
Recognized Net Loss Due to Lump Sum Settlements [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	119	312	161
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(30)	(77)	(39)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	89	235	122
Pension and Other Postretirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	(3,731)	(4,345)	5,378
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	932	1,086	(1,344)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	$ (2,799)	(3,259)	4,034
Cash Flow Hedge Derivatives {Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount		(145)	497
Reclassification from accumulated other comprehensive income, current period, before tax amount		(479)	(322)
Other comprehensive income (loss), before tax amount		(624)	175
Other comprehensive income (loss), before reclassifications, tax (expense) benefit		36	(124)
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit		119	80
Other comprehensive income (loss), tax (expense) benefit		155	(44)
Other comprehensive income (loss), before reclassifications, net of tax amount		(109)	373
Reclassification from accumulated other comprehensive income, current period, net of tax amount		(360)	(242)
Other comprehensive income (loss), net of tax amount		$ (469)	$ 131

Shareholders' Equity - Changes

Shareholders' Equity - Changes in Balances of Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 1,660,702	$ 1,591,453	$ 1,571,701
Other comprehensive income (loss) before reclassification	21,502	31,420	(8,416)
Amounts reclassified from accumulated other comprehensive loss	1,047	659	986
Other comprehensive income (loss), net of tax amount	22,549	32,079	(7,430)
Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act			(8,524)
Balance	1,741,117	1,660,702	1,591,453
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(8,017)	(43,824)	(26,535)
Other comprehensive income (loss) before reclassification	25,348	35,807	(11,595)
Other comprehensive income (loss), net of tax amount	25,348	35,807	(11,595)
Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act			(5,694)
Balance	17,331	(8,017)	(43,824)
Defined Benefit Pension Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(15,583)	(12,324)	(13,468)
Other comprehensive income (loss) before reclassification	(3,846)	(4,278)	2,806
Amounts reclassified from accumulated other comprehensive loss	1,047	1,019	1,228
Other comprehensive income (loss), net of tax amount	(2,799)	(3,259)	4,034
Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act			(2,890)
Balance	(18,382)	(15,583)	(12,324)
Cash Flow Hedge Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance		469	278
Other comprehensive income (loss) before reclassification		(109)	373
Amounts reclassified from accumulated other comprehensive loss		(360)	(242)
Other comprehensive income (loss), net of tax amount		(469)	131
Reclassification of certain income tax effects related to the change in the federal statutory income tax rate under the Tax Reform Act			60
Balance			469
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(23,600)	(55,679)	(39,725)
Balance	$ (1,051)	$ (23,600)	$ (55,679)

Fair Value - Financial Assets a

Fair Value - Financial Assets and Liabilities Measured at Fair Value Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 1,991,815	$ 1,602,404
Loans held for sale	446,951	226,347
Mortgage servicing rights	66,464	79,394	$ 95,596
U.S. Government Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	18,041	22,327
Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	5,835	25,465
Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,991,815	1,602,404
Loans held for sale	446,951	226,347
Mortgage servicing rights	66,464	79,394
Other assets - derivatives	47,768	17,956
Other liabilities - derivatives	5,324	6,063
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	18,041	22,327
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	5,835	25,465
Recurring Basis [Member] | Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,967,939	1,554,612
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	145	244
Other liabilities - derivatives	666	4,414
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	1,991,815	1,602,404
Loans held for sale	446,951	226,347
Mortgage servicing rights	0	0
Other assets - derivatives	38,063	16,273
Other liabilities - derivatives	4,658	1,649
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	18,041	22,327
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	5,835	25,465
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	1,967,939	1,554,612
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	66,464	79,394
Other assets - derivatives	9,560	1,439
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, 2020	Dec. 31, 2019
MSR [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		$ 79,394	$ 95,596
Total net (loss) gain included in Mortgage banking, net	[1]	(42,735)	(32,913)
Additions		29,805	16,711
Sales		0	0
Ending Balance		66,464	79,394
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		(26,146)	(21,078)
Other Assets - Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		1,439	1,187
Total net (loss) gain included in Mortgage banking, net	[1]	40,669	6,775
Additions		0	0
Sales		(32,548)	(6,523)
Ending Balance		9,560	1,439
The amount of total gains (losses) for the period included in earnings that are attributable to the change in unrealized gains or losses still held, end of period		$ 25,031	$ 1,284
[1]	Total net (loss) gain included in Mortgage banking, net relating to the MSR includes changes in fair value due to market changes and due to run-off.

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Outstanding balances in collateral dependent related to allowance for credit losses	$ 43,400
Collateral dependent related to allowance for credit losses	4,400
Outstanding balances in impaired loans		$ 41,200
Impaired loans, related allowance		5,500
Foreclosed assets re-measured after initial recognition	10,100	15,000
Write-downs of allowance for foreclosed assets after initial recognition	2,000	2,400
Noninterest gain (loss) Mortgage banking, net for changes in fair value of LHFS	10,500	1,500	$ 1,400
Interest earned on LHFS included in Interest and fees on LHFS and LHFI	6,900	5,900	$ 4,900
Serviced GNMA loans eligible for repurchase	$ 141,160	$ 57,062

Fair Value - Carrying Amounts a

Fair Value - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity		$ 538,072	$ 738,099
Net acquired loans			71,786
Deposits		14,048,764	11,245,557
Federal funds purchased and securities sold under repurchase agreements		164,519	256,020
Other borrowings		168,252	85,396
Subordinated notes		122,921
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		1,952,554	358,916
Securities held to maturity		538,072	738,099
Deposits		14,048,764	11,245,557
Federal funds purchased and securities sold under repurchase agreements		164,519	256,020
Other borrowings		168,252	85,396
Subordinated notes		122,921	0
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		1,952,554	358,916
Securities held to maturity		563,115	746,202
Deposits		14,052,863	11,250,071
Federal funds purchased and securities sold under repurchase agreements		164,519	256,020
Other borrowings		168,252	85,374
Subordinated notes		127,500	0
Junior subordinated debt securities		46,083	50,722
Level 3 [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI and PPP loans		10,317,352	9,251,351
Net acquired loans	[1]	0	71,786
Level 3 [Member] | Estimate Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI and PPP loans		10,312,395	9,235,674
Net acquired loans	[1]	$ 0	$ 71,786
[1]	Upon adoption of FASB ASC Topic 326 at January 1, 2020, Trustmark elected to account for its existing acquired loans as purchased credit deteriorated loans included within the LHFI portfolio. See Note 5 – Acquired Loans for additional details.

Fair Value - Fair Value and the

Fair Value - Fair Value and the Contractual Principal Outstanding of the LHFS (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair value and the contractual principal outstanding of the LHFS [Abstract]
Fair value of LHFS	$ 305,791	$ 169,285
LHFS contractual principal outstanding	290,625	164,420
Fair value less unpaid principal	$ 15,166	$ 4,865

Derivative Financial Instrume_3

Derivative Financial Instruments - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020USD ($)Contract	Dec. 31, 2019USD ($)Contract	Dec. 31, 2018USD ($)	Apr. 04, 2013USD ($)
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Period for which cash flow hedges will be used to hedge quarterly interest payments	5 years
Derivative inception date	Dec. 31, 2014
Derivative maturity date	Dec. 31, 2019
Description of variable rate basis for derivative	three-month LIBOR
Ineffectiveness related to interest rate swap designated as a cash flow hedge	$ 0	$ 0	$ 0
Accumulated net, after tax gain included in accumulated other comprehensive income (loss)	$ 0	$ 0
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Junior Subordinated Debentures [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total notional amount				$ 60,000,000
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Three-month LIBOR [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Swap fixed interest rate to be paid	1.66%
Derivatives not Designated as Hedging Instruments [Member] | Beneficiary [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Number of risk participation agreements | Contract	3	3
Aggregate notional amount of credit risk participation agreements	$ 41,100,000	$ 37,600,000
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	24	10
Aggregate notional amount of credit risk participation agreements	$ 172,000,000	$ 79,300,000
Derivatives not Designated as Hedging Instruments [Member] | Mortgage Servicing Rights Hedge [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total notional amount	326,500,000	564,000,000
Net (negative) positive ineffectiveness on MSR fair value	7,800,000	(11,500,000)	$ 2,400,000
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Swap [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total notional amount	1,125,000,000	893,100,000
Termination value of derivatives	1,300,000	1,000,000
Collateral Posted	1,600,000
Derivatives not Designated as Hedging Instruments [Member] | Forward Contracts [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet obligations	377,500,000	209,000,000
Valuation adjustment	(3,100,000)	(486,000)
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	329,300,000	92,100,000
Valuation adjustment	$ 9,600,000	$ 1,400,000

Derivative Financial Instrume_4

Derivative Financial Instruments - Fair Value of Derivative Instruments (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset		$ 37,974	$ 16,209
Fair value of derivative liability		1,313	1,122
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		89	64
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		200	41
Derivatives not Designated as Hedging Instruments [Member] | Future Contracts [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability		34	2,654
Derivatives not Designated as Hedging Instruments [Member] | Forward Contracts [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability		3,145	486
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		145	244
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		9,560	1,439
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Swap [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	[1]	37,974	16,209
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Swap [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	[1]	1,313	1,122
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		$ 632	$ 1,760
[1]	In accordance with GAAP, the variation margin collateral payments made or received for interest rate swaps that are centrally cleared are legally characterized as settled. As a result, the centrally cleared interest rate swaps included in other assets and other liabilities are presented on a net basis in the accompanying consolidated balance sheets.

Derivative Financial Instrume_5

Derivative Financial Instruments - Effects of Derivative Instruments on Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivatives in Hedging Relationships [Member] | Accumulated Other Comprehensive Income (Loss) and Other Interest Expense [Member]
Derivatives, Fair Value [Line Items]
Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) and recognized in other interest expense		$ 479	$ 322
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	$ 39,436	11,096	(6,191)
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	$ (1,022)	$ (776)	$ (357)

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss), net of tax	$ 0	$ (109)	$ 373
Derivatives in Hedging Relationships [Member]
Derivatives, Fair Value [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss), net of tax		$ (109)	$ 373

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, 2020	Dec. 31, 2019
Offsetting Derivative Assets
Gross Amounts of Recognized Assets, Offsetting of Derivative Assets	$ 37,974	$ 16,209
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	37,974	16,209
Financial Instruments, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Assets	0
Cash Collateral Received, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Assets	0
Net Amount, Offsetting of Derivative Assets	37,974	16,209
Offsetting Derivative Liabilities
Gross Amounts of Recognized Liabilities, Offsetting of Derivative Liabilities	1,313	1,122
Gross Amounts Offset in the Statement of Financial Position, Offsetting of Derivative Liabilities	0	0
Net Amounts of Liabilities presented in the Statement of Financial Position, Offsetting of Derivative Liabilities	1,313	1,122
Financial Instruments, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Liabilities	0
Cash Collateral Posted, Gross Amounts Not Offset in the Statement of Financial Position, Offsetting of Derivative Liabilities	$ (1,313)	(1,390)
Net Amount, Offsetting of Derivative Liabilities		$ (268)

Segment Information - Additiona

Segment Information - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020Segment
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, 2020	Dec. 31, 2019		Dec. 31, 2018
Segment Reporting Information [Line Items]
Net interest income	$ 426,537	$ 426,589		$ 419,420
Provision for loan losses, net	36,113	10,839		16,988
Noninterest income	274,593	187,045	[1]	184,836	[1]
Noninterest expense	475,235	429,002		415,415
Income Before Income Taxes	189,782	173,793		171,853
Income taxes	29,757	23,333		22,269
Net Income	160,025	150,460		149,584
Selected Financial Information
Total assets	16,551,840	13,497,877		13,286,460
Depreciation and amortization	41,325	39,420		38,940
General Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	420,225	419,597		412,455
Provision for loan losses, net	36,124	10,622		17,098
Noninterest income	197,691	113,756	[1]	113,930	[1]
Noninterest expense	410,744	367,976		353,174
Income Before Income Taxes	171,048	154,755		156,113
Income taxes	25,109	18,638		18,313
Net Income	145,939	136,117		137,800
Selected Financial Information
Total assets	16,226,358	13,140,467		12,896,799
Depreciation and amortization	40,351	38,634		38,181
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest income	6,082	6,750		6,739
Provision for loan losses, net	(11)	217		(110)
Noninterest income	31,634	30,860	[1]	30,420	[1]
Noninterest expense	30,318	28,882		31,385
Income Before Income Taxes	7,409	8,511		5,884
Income taxes	1,853	2,123		1,472
Net Income	5,556	6,388		4,412
Selected Financial Information
Total assets	242,429	283,164		320,742
Depreciation and amortization	274	270		187
Insurance [Member]
Segment Reporting Information [Line Items]
Net interest income	230	242		226
Noninterest income	45,268	42,429	[1]	40,486	[1]
Noninterest expense	34,173	32,144		30,856
Income Before Income Taxes	11,325	10,527		9,856
Income taxes	2,795	2,572		2,484
Net Income	8,530	7,955		7,372
Selected Financial Information
Total assets	83,053	74,246		68,919
Depreciation and amortization	$ 700	$ 516		$ 572
[1]	During the first quarter of 2020, Trustmark revised the composition of its operating segments by moving the Retail Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes.  The prior period amounts presented include reclassifications to conform to the current period presentation.

Parent Company Only Financial_3

Parent Company Only Financial Information - Parent Only Financial Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Other assets	$ 609,142	$ 532,389
Total Assets	16,551,840	13,497,877	$ 13,286,460
Liabilities and Shareholders' Equity:
Subordinated notes	122,921
Junior subordinated debt securities	61,856	61,856
Shareholders' equity	1,741,117	1,660,702	1,591,453	$ 1,571,701
Total Liabilities and Shareholders' Equity	16,551,840	13,497,877
Expense:
Net Income	160,025	150,460	149,584
Operating Activities
Net income	160,025	150,460	149,584
Adjustments to reconcile net income to net cash provided by operating activities:
Other	27,699	23,838	(6,886)
Net cash from operating activities	65,346	116,447	239,198
Financing Activities
Proceeds from subordinated notes	122,900	0	0
Common stock dividends	(58,769)	(59,804)	(62,425)
Repurchase and retirement of common stock	(27,538)	(56,615)	(62,421)
Net cash from financing activities	2,745,957	(32,853)	(664,192)
Trustmark Corp (Parent Company Only) [Member]
Assets
Investment in banks	1,769,165	1,707,644
Other assets	158,360	15,778
Total Assets	1,927,525	1,723,422
Liabilities and Shareholders' Equity:
Accrued expense	1,631	864
Subordinated notes	122,921
Junior subordinated debt securities	61,856	61,856
Shareholders' equity	1,741,117	1,660,702
Total Liabilities and Shareholders' Equity	1,927,525	1,723,422
Revenue:
Dividends received from banks	109,243	120,297	128,592
Earnings of subsidiaries over distributions	53,724	32,971	23,791
Other income	66	90	86
Total Revenue	163,033	153,358	152,469
Expense:
Other expense	3,008	2,898	2,885
Total Expense	3,008	2,898	2,885
Net Income	160,025	150,460	149,584
Operating Activities
Net income	160,025	150,460	149,584
Adjustments to reconcile net income to net cash provided by operating activities:
Net change in investment in subsidiaries	(53,724)	(32,971)	(23,791)
Other	(326)	(1,800)	(1,395)
Net cash from operating activities	105,975	115,689	124,398
Financing Activities
Proceeds from subordinated notes	122,900
Common stock dividends	(58,769)	(59,804)	(62,425)
Repurchase and retirement of common stock	(27,538)	(56,615)	(62,421)
Net cash from financing activities	36,593	(116,419)	(124,846)
Net change in cash and cash equivalents	142,568	(730)	(448)
Cash and cash equivalents at beginning of year	15,707	16,437	16,885
Cash and cash equivalents at end of year	$ 158,275	$ 15,707	$ 16,437

Parent Company Only Financial_4

Parent Company Only Financial Information - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements Captions [Line Items]
Income taxes paid	$ 46,648,000	$ 24,809,000	$ 12,435,000
Trustmark Corp (Parent Company Only) [Member]
Condensed Financial Statements Captions [Line Items]
Income taxes paid	46,600,000	24,800,000	12,400,000
Interest paid	0
Interest received	$ 0	$ 482,000	$ 320,000