Southside Bancshares (SBSI) 10-Q 30 Apr 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 27, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	000-12247
Entity Registrant Name	SOUTHSIDE BANCSHARES, INC.
Entity Incorporation, State or Country Code	TX
Entity Tax Identification Number	75-1848732
Entity Address, Address Line One	1201 S. Beckham Avenue,
Entity Address, City or Town	Tyler,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75701
City Area Code	903
Local Phone Number	531-7111
Title of 12(b) Security	Common Stock, $1.25 par value
Trading Symbol	SBSI
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		32,588,244
Entity Central Index Key	0000705432
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS (UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($)		Mar. 31, 2021	Dec. 31, 2020
ASSETS
Cash and due from banks		$ 78,304,000	$ 87,357,000
Interest earning deposits		29,319,000	21,051,000
Total cash and cash equivalents		107,623,000	108,408,000
Securities AFS, at estimated fair value (amortized cost of $2,448,113 and $2,437,513, respectively)		2,546,924,000	2,587,305,000
Securities HTM (estimated fair value of $104,177 and $118,198, respectively)		98,159,000	108,998,000
FHLB stock, at cost		18,754,000	25,259,000
Equity investments		11,804,000	11,905,000
Loans held for sale		2,615,000	3,695,000
Loans:
Loans		3,716,598,000	3,657,779,000
Less: Allowance for loan losses		(41,454,000)	(49,006,000)
Net loans		3,675,144,000	3,608,773,000
Premises and equipment, net		144,628,000	144,576,000
Operating lease ROU assets		15,788,000	15,063,000
Goodwill		201,116,000	201,116,000
Other intangible assets, net		8,978,000	9,744,000
Interest receivable		27,438,000	38,708,000
BOLI		116,209,000	115,583,000
Other assets		23,706,000	29,094,000
Total assets		6,998,886,000	7,008,227,000
Deposits:
Noninterest bearing		1,383,371,000	1,354,815,000
Interest bearing		3,709,272,000	3,577,507,000
Total deposits		5,092,643,000	4,932,322,000
Other borrowings		22,315,000	23,172,000
FHLB borrowings		665,530,000	832,527,000
Subordinated notes, net of unamortized debt issuance costs	[1]	197,268,000	197,251,000
Trust preferred subordinated debentures, net of unamortized debt issuance costs		60,256,000	60,255,000
Deferred tax liability, net		9,869,000	15,549,000
Unsettled trades to purchase securities		23,473,000	0
Operating lease liabilities		17,327,000	16,734,000
Other liabilities		51,608,000	55,120,000
Total liabilities		6,140,289,000	6,132,930,000
Off-balance-sheet arrangements, commitments and contingencies (Note 12)
Shareholders’ equity:
Common stock:  ($1.25 par value, 80,000,000 shares authorized, 37,943,737 shares issued at March 31, 2021 and 37,934,819 shares issued at December 31, 2020)		47,430,000	47,419,000
Paid-in capital		774,815,000	771,511,000
Retained earnings		134,782,000	111,208,000
Treasury stock: (shares at cost, 5,284,781 at March 31, 2021 and 4,983,645 at December 31, 2020)		(138,016,000)	(123,921,000)
AOCI		39,586,000	69,080,000
Total shareholders’ equity		858,597,000	875,297,000
Total liabilities and shareholders’ equity		$ 6,998,886,000	$ 7,008,227,000
[1]	This debt consists of subordinated notes with a remaining maturity greater than one year that qualify under the risk-based capital guidelines as Tier 2 capital, subject to certain limitations.

CONSOLIDATED BALANCE SHEETS (_2

CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Available-for-sale [Abstract]
Securities available for sale, amortized cost	$ 2,448,113	$ 2,437,513
Held-to-maturity Securities, Other Disclosure Items [Abstract]
Securities held to maturity, fair value	$ 104,177	$ 118,198
Shareholders' equity:
Common stock, par value (in dollars per share)	$ 1.25	$ 1.25
Common stock, shares authorized (in shares)	80,000,000	80,000,000
Common stock, shares issued (in shares)	37,943,737	37,934,819
Treasury stock (in shares)	5,284,781	4,983,645

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest income:
Loans	$ 36,038	$ 41,895
Taxable investment securities	2,323	512
Tax-exempt investment securities	8,965	6,206
MBS	6,088	11,534
FHLB stock and equity investments	136	425
Other interest earning assets	15	180
Total interest income	53,565	60,752
Interest expense:
Deposits	2,597	9,919
FHLB borrowings	1,908	3,974
Subordinated notes	2,395	1,411
Trust preferred subordinated debentures	351	600
Other borrowings	11	147
Total interest expense	7,262	16,051
Net interest income	46,303	44,701
Provision for credit losses	(10,149)	25,247
Net interest income after provision for credit losses	56,452	19,454
Noninterest income:
Deposit services	6,125	6,279
Net gain on sale of securities AFS	2,003	5,541
Gain on sale of loans	593	170
Trust fees	1,383	1,305
BOLI	626	569
Brokerage services	780	580
Other	2,113	1,054
Total noninterest income	13,623	15,498
Noninterest expense:
Salaries and employee benefits	20,044	19,643
Net occupancy	3,560	3,311
Advertising, travel & entertainment	437	832
ATM expense	238	224
Professional fees	991	1,195
Software and data processing	1,312	1,227
Communications	525	493
FDIC insurance	454	25
Amortization of intangibles	766	980
Other	2,907	2,590
Total noninterest expense	31,234	30,520
Income before income tax expense	38,841	4,432
Income tax expense	4,750	479
Net income	$ 34,091	$ 3,953
Earnings per common share - basic (in dollars per share)	$ 1.04	$ 0.12
Earnings per common share - diluted (in dollars per share)	1.04	0.12
Cash dividends paid per common share (in dollars per share)	$ 0.32	$ 0.31

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 34,091	$ 3,953
Securities AFS and transferred securities:
Change in unrealized holding (loss) gain on AFS securities during the period	(48,979)	61,486
Reclassification adjustment for amortization related to AFS and HTM debt securities	416	121
Reclassification adjustment for net gain on sale of AFS securities, included in net income	(2,003)	(5,541)
Derivatives:
Change in net unrealized gain (loss) on effective cash flow hedge interest rate swap derivatives	11,023	(19,600)
Reclassification adjustment of net loss (gain) related to derivatives designated as cash flow hedges	1,568	(101)
Pension plans:
Amortization of net actuarial loss and prior service credit, included in net periodic benefit cost	641	727
Other comprehensive (loss) income, before tax	(37,334)	37,092
Income tax benefit (expense) related to items of other comprehensive (loss) income	7,840	(7,789)
Other comprehensive (loss) income, net of tax	(29,494)	29,303
Comprehensive income	$ 4,597	$ 33,256

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock	Paid In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Cumulative effect of accounting change	Cumulative effect of accounting changeRetained Earnings	Adjusted beginning balance	Adjusted beginning balanceCommon Stock	Adjusted beginning balancePaid In Capital	Adjusted beginning balanceRetained Earnings	Adjusted beginning balanceTreasury Stock	Adjusted beginning balanceAccumulated Other Comprehensive Income (Loss)
Beginning balance, net of tax at Dec. 31, 2019	$ 804,580	$ 47,360	$ 766,718	$ 80,274	$ (94,008)	$ 4,236	$ (7,830)	$ (7,830)	$ 796,750	$ 47,360	$ 766,718	$ 72,444	$ (94,008)	$ 4,236
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,953			3,953
Other comprehensive (loss) income	29,303					29,303
Issuance of common stock for dividend reinvestment plan	347	13	334
Purchase of common stock	(25,842)				(25,842)
Stock compensation expense	695		695
Net issuance of common stock under employee stock plans	1,088		693	(40)	435
Cash dividends paid on common stock	(10,494)			(10,494)
Ending balance, net of tax at Mar. 31, 2020	795,800	47,373	768,440	65,863	(119,415)	33,539
Beginning balance, net of tax at Dec. 31, 2020	875,297	47,419	771,511	111,208	(123,921)	69,080
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	34,091			34,091
Other comprehensive (loss) income	(29,494)					(29,494)
Issuance of common stock for dividend reinvestment plan	332	11	321
Purchase of common stock	(15,213)				(15,213)
Stock compensation expense	674		674
Net issuance of common stock under employee stock plans	3,386		2,309	(41)	1,118
Cash dividends paid on common stock	(10,476)			(10,476)
Ending balance, net of tax at Mar. 31, 2021	$ 858,597	$ 47,430	$ 774,815	$ 134,782	$ (138,016)	$ 39,586

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Issuance of common stock for dividend reinvestment plan (in shares)	8,918	10,607
Common stock purchased (in shares)	427,396	869,723
Net issuance of common stock under employee stock plans (in shares)	126,260	47,428
Cash dividends paid on common stock (in dollars per share)	$ 0.32	$ 0.31

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
OPERATING ACTIVITIES:
Net income	$ 34,091,000	$ 3,953,000
Adjustments to reconcile net income to net cash provided by operations:
Depreciation and net amortization	2,882,000	3,021,000
Securities premium amortization (discount accretion), net	6,083,000	4,505,000
Loan (discount accretion) premium amortization, net	(223,000)	(244,000)
Provision for credit losses	(10,149,000)	25,247,000
Stock compensation expense	674,000	695,000
Deferred tax expense (benefit)	2,161,000	(5,075,000)
Net gain on sale of AFS securities	(2,003,000)	(5,541,000)
Net (gain) loss on premises and equipment	227,000	(42,000)
Gross proceeds from sales of loans held for sale	15,987,000	5,204,000
Gross originations of loans held for sale	(14,907,000)	(6,651,000)
Net (gain) loss on OREO	(2,000)	1,000
Net change in:
Interest receivable	11,270,000	1,383,000
Other assets	6,459,000	(9,318,000)
Interest payable	(1,026,000)	(2,034,000)
Other liabilities	10,891,000	(18,886,000)
Net cash provided by (used in) operating activities	62,415,000	(3,782,000)
Securities AFS:
Purchases	(127,713,000)	(683,062,000)
Sales	37,097,000	135,000,000
Maturities, calls and principal repayments	99,787,000	80,555,000
Securities HTM:
Maturities, calls and principal repayments	10,871,000	352,000
Proceeds from redemption of FHLB stock and equity investments	16,240,000	0
Purchases of FHLB stock and equity investments	(9,629,000)	(4,661,000)
Net loan originations	(59,211,000)	(33,207,000)
Purchases of premises and equipment	(2,396,000)	(4,259,000)
Proceeds from sales of premises and equipment	94,000	72,000
Proceeds from sales of OREO	106,000	46,000
Proceeds from sales of repossessed assets	44,000	31,000
Net cash used in investing activities	(34,710,000)	(509,133,000)
FINANCING ACTIVITIES:
Net change in deposits	160,308,000	56,281,000
Net change in other borrowings	(857,000)	189,542,000
Proceeds from FHLB borrowings	4,009,977,000	3,247,401,000
Repayment of FHLB borrowings	(4,176,974,000)	(2,945,775,000)
Net proceeds from issuance of subordinated long-term debt	(59,000)	0
Proceeds from stock option exercises	3,412,000	1,130,000
Cash paid to tax authority related to tax withholding on share-based awards	(26,000)	(42,000)
Purchase of common stock	(14,127,000)	(23,959,000)
Proceeds from the issuance of common stock for dividend reinvestment plan	332,000	347,000
Cash dividends paid	(10,476,000)	(10,494,000)
Net cash (used in) provided by financing activities	(28,490,000)	514,431,000
Net (decrease) increase in cash and cash equivalents	(785,000)	1,516,000
Cash and cash equivalents at beginning of period	108,408,000	110,697,000
Cash and cash equivalents at end of period	107,623,000	112,213,000
SUPPLEMENTAL DISCLOSURES FOR CASH FLOW INFORMATION:
Interest paid	8,288,000	18,085,000
Income taxes paid	250,000	0
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Loans transferred to other repossessed assets and real estate through foreclosure	424,000	338,000
Unsettled trades to purchase securities	(23,473,000)	(14,596,000)
Unsettled trades to sell securities	0	67,247,000
Unsettled trades to repurchase common stock	$ (1,086,000)	$ (1,883,000)

Summary of Significant Accounti

Summary of Significant Accounting and Reporting Policies	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting and Reporting Policies	Summary of Significant Accounting and Reporting Policies Basis of Presentation In this report, the words “the Company,” “we,” “us,” and “our” refer to the combined entities of Southside Bancshares, Inc. and its subsidiaries, including Southside Bank. The words “Southside” and “Southside Bancshares” refer to Southside Bancshares, Inc. The words “Southside Bank” and “the Bank” refer to Southside Bank. The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, not all information required by GAAP for complete financial statements is included in these interim statements. In the opinion of management, all adjustments necessary for a fair presentation of such financial statements have been included. Such adjustments consisted only of normal recurring items. The preparation of these consolidated financial statements in accordance with GAAP requires the use of management’s estimates. These estimates are subjective in nature and involve matters of judgment. Actual amounts could differ from these estimates. Interim results are not necessarily indicative of results for a full year. These financial statements should be read in conjunction with the financial statements and notes thereto in our Annual Report on Form 10-K for the year ended December 31, 2020. Accounting Changes and Reclassifications Certain prior period amounts may be reclassified to conform to current year presentation. Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” ASU 2020-04 is intended to provide relief for companies preparing for discontinuation of interest rates based on LIBOR. The ASU provides optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or other reference rates expected to be discontinued. ASU 2020-04 also provides for a one-time sale and/or transfer to AFS or trading to be made for HTM debt securities that both reference an eligible reference rate and were classified as HTM before January 1, 2020. ASU 2020-04 was effective for all entities as of March 12, 2020 and through December 31, 2022. Companies can apply the ASU as of the beginning of the interim period that includes March 12, 2020 or any date thereafter. The guidance requires companies to apply the guidance prospectively to contract modifications and hedging relationships while the one-time election to sell and/or transfer debt securities classified as HTM may be made any time after March 12, 2020. We have established an officer level committee to guide our transition from LIBOR and have begun efforts to transition to alternative rates consistent with industry timelines. We have identified products that utilize LIBOR and are implementing enhanced fallback language to facilitate the transition to alternative reference rates. We are evaluating existing systems and have begun offering new rates on a limited basis. ASU 2020-04 is not expected to have a material impact on our consolidated financial statements.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Earnings per share on a basic and diluted basis are calculated as follows (in thousands, except per share amounts): Three Months Ended 2021 2020 Basic and Diluted Earnings: Net income $ 34,091 $ 3,953 Basic weighted-average shares outstanding 32,829 33,691 Add: Stock awards 108 114 Diluted weighted-average shares outstanding 32,937 33,805 Basic earnings per share: Net income $ 1.04 $ 0.12 Diluted earnings per share: Net income $ 1.04 $ 0.12 For the three months ended March 31, 2021, and 2020 there were approximately 679,000 and 775,000 anti-dilutive shares, respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The changes in accumulated other comprehensive income (loss) by component are as follows (in thousands): Three Months Ended March 31, 2021 Pension Plans Unrealized Gains (Losses) on Securities Unrealized Gains (Losses) on Derivatives Net Prior Net Gain (Loss) Total Beginning balance, net of tax $ 116,078 $ (17,091) $ 149 $ (30,056) $ 69,080 Other comprehensive income (loss): Other comprehensive (loss) income before reclassifications (48,979) 11,023 — — (37,956) Reclassification adjustments included in net income (1,587) 1,568 — 641 622 Income tax benefit (expense) 10,619 (2,644) — (135) 7,840 Net current-period other comprehensive (loss) income, net of tax (39,947) 9,947 — 506 (29,494) Ending balance, net of tax $ 76,131 $ (7,144) $ 149 $ (29,550) $ 39,586 Three Months Ended March 31, 2020 Pension Plans Unrealized Gains (Losses) on Securities Unrealized Gains (Losses) on Derivatives Net Prior Service (Cost) Credit Net Gain (Loss) Total Beginning balance, net of tax $ 38,038 $ (1,672) $ (145) $ (31,985) $ 4,236 Other comprehensive income (loss): Other comprehensive income (loss) before reclassifications 61,486 (19,600) — — 41,886 Reclassification adjustments included in net income (5,420) (101) (1) 728 (4,794) Income tax (expense) benefit (11,774) 4,137 — (152) (7,789) Net current-period other comprehensive income (loss), net of tax 44,292 (15,564) (1) 576 29,303 Ending balance, net of tax $ 82,330 $ (17,236) $ (146) $ (31,409) $ 33,539 The reclassification adjustments out of accumulated other comprehensive income (loss) included in net income are presented below (in thousands): Three Months Ended 2021 2020 Unrealized gains and losses on securities transferred: Amortization of unrealized gains and losses (1) $ (416) $ (121) Tax benefit 87 25 Net of tax (329) (96) Unrealized gains and losses on available for sale securities: Realized net gain on sale of securities (2) 2,003 5,541 Tax expense (420) (1,164) Net of tax 1,583 4,377 Derivatives: Realized net (loss) gain on interest rate swap derivatives (3) (1,568) 93 Tax benefit (expense) 329 (19) Net of tax (1,239) 74 Amortization of unrealized gains on terminated interest rate swap derivatives (3) — 8 Tax expense — (1) Net of tax — 7 Amortization of pension plan: Net actuarial loss (4) (641) (728) Prior service credit (4) — 1 Total before tax (641) (727) Tax benefit 135 152 Net of tax (506) (575) Total reclassifications for the period, net of tax $ (491) $ 3,787 (1) Included in interest income on the consolidated statements of income. (2) Listed as net gain on sale of securities AFS on the consolidated statements of income. (3) Included in interest expense for FHLB borrowings on the consolidated statements of income. (4) These AOCI components are included in the computation of net periodic pension cost (income) presented in “Note 8 – Employee Benefit Plans.”

Securities

Securities	3 Months Ended
	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Securities	Securities Debt securities The amortized cost, gross unrealized gains and losses and estimated fair value of investment and mortgage-backed AFS and HTM securities as of March 31, 2021 and December 31, 2020 are reflected in the tables below (in thousands): March 31, 2021 Amortized Gross Unrealized Gross Unrealized Estimated AVAILABLE FOR SALE Cost Gains Losses Fair Value Investment securities: U.S. Treasury $ 42,818 $ 8 $ 349 $ 42,477 State and political subdivisions 1,528,516 71,813 8,684 1,591,645 Other stocks and bonds 91,439 1,560 216 92,783 MBS: (1) Residential 675,795 31,580 301 707,074 Commercial 109,545 3,802 402 112,945 Total $ 2,448,113 $ 108,763 $ 9,952 $ 2,546,924 HELD TO MATURITY Investment securities: State and political subdivisions $ 908 $ 9 $ — $ 917 MBS: (1) Residential 45,274 3,006 — 48,280 Commercial 51,977 3,003 — 54,980 Total $ 98,159 $ 6,018 $ — $ 104,177 December 31, 2020 Amortized Gross Unrealized Gross Unrealized Estimated AVAILABLE FOR SALE Cost Gains Losses Fair Value Investment securities: State and political subdivisions $ 1,475,030 $ 105,601 $ 37 $ 1,580,594 Other stocks and bonds 77,224 1,053 22 78,255 MBS: (1) Residential 771,409 38,674 73 810,010 Commercial 113,850 4,746 150 118,446 Total $ 2,437,513 $ 150,074 $ 282 $ 2,587,305 HELD TO MATURITY Investment securities: State and political subdivisions $ 907 $ 13 $ — $ 920 MBS: (1) Residential 47,948 4,187 — 52,135 Commercial 60,143 5,000 — 65,143 Total $ 108,998 $ 9,200 $ — $ 118,198 (1) All MBS issued and/or guaranteed by U.S. government agencies or U.S. GSEs. Investment securities and MBS with carrying values of $1.47 billion and $1.56 billion were pledged as of March 31, 2021 and December 31, 2020, respectively, to collateralize FHLB borrowings, borrowings from the FRDW, repurchase agreements and public fund deposits, for potential liquidity needs or other purposes as required by law. The following tables represent the fair value and unrealized losses on AFS investment and MBS for which an allowance for credit losses has not been recorded as of March 31, 2021 and December 31, 2020, segregated by major security type and length of time in a continuous loss position (in thousands): March 31, 2021 Less Than 12 Months More Than 12 Months Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss AVAILABLE FOR SALE Investment securities: U.S. Treasury $ 23,599 $ 349 $ — $ — $ 23,599 $ 349 State and political subdivisions 205,469 8,684 — — 205,469 8,684 Other stocks and bonds 28,845 216 — — 28,845 216 MBS: Residential 7,769 301 — — 7,769 301 Commercial 4,488 402 — — 4,488 402 Total $ 270,170 $ 9,952 $ — $ — $ 270,170 $ 9,952 December 31, 2020 Less Than 12 Months More Than 12 Months Total Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized AVAILABLE FOR SALE Investment securities: State and political subdivisions $ 17,305 $ 37 $ — $ — $ 17,305 $ 37 Other stocks and bonds 11,562 22 — — 11,562 22 MBS: Residential 6,287 73 — — 6,287 73 Commercial 4,744 150 — — 4,744 150 Total $ 39,898 $ 282 $ — $ — $ 39,898 $ 282 With the adoption of ASU 2016-13, for those AFS debt securities in an unrealized loss position where management (i) has the intent to sell or (ii) where it will more-likely-than-not be required to sell the security before the recovery of its amortized cost basis, we write the security down to fair value with an adjustment to earnings. For those AFS debt securities in an unrealized loss position that do not meet either of these criteria, management assesses whether the decline in fair value has resulted from credit-related factors, using both qualitative and quantitative criteria. Determining the allowance under the credit loss method requires the use of a discounted cash flow method to assess the credit losses. Any credit-related impairment will be recognized in allowance for credit losses on the balance sheet with a corresponding adjustment to earnings. Noncredit-related impairment, the portion of the impairment relating to factors other than credit (such as changes in market interest rates), is recognized in other comprehensive income, net of tax. Based on our consideration of the qualitative factors associated with each security type in our AFS portfolio, we did not recognize any unrealized losses in income on our AFS securities during the three months ended March 31, 2021 or 2020. Our state and political subdivisions are highly rated municipal securities with a long history of no credit losses. Our AFS MBS are highly rated securities which are either explicitly or implicitly backed by the U.S. Government through its agencies which are highly rated by major ratings agencies and also have a long history of no credit losses. Our other stocks and bonds as of March 31, 2021 consist of highly rated investment grade bonds. Management does not intend to sell and it is likely we will not be required to sell those securities in an unrealized loss position prior to the anticipated recovery of the amortized cost basis. These unrealized losses on our investment and MBS are largely due to changes in interest rates and spreads and other market conditions impacted by COVID-19. As of March 31, 2021 and December 31, 2020, we did not have an allowance for credit losses on our AFS securities. We assess the likelihood of default and the potential amount of default when assessing our HTM securities for credit losses. We utilize term structures and, due to no prior loss exposure on our state and political subdivision securities, we currently apply a third-party average loss given default rate to model our securities. Due to a small number of HTM municipal securities in our portfolio as of March 31, 2021 and 2020, we elected to use the specific identification method to model these securities which aligns with our third-party fair value measurement process. The model determined any expected credit loss over the life of these securities to be remote. Management further evaluated the remote expectation of loss along with the qualitative factors associated with these securities and concluded that, due to the securities being highly rated municipals with a long history of no credit losses, no credit loss should be recognized for these securities for the three months ended March 31, 2021 or 2020. From time to time, we have transferred securities from AFS to HTM due to overall balance sheet strategies. The remaining net unamortized, unrealized loss on the transferred securities included in AOCI in the accompanying balance sheets totaled $2.4 million ($1.9 million, net of tax) at March 31, 2021 and $2.9 million ($2.3 million, net of tax) at December 31, 2020. Any net unrealized gain or loss on the transferred securities included in AOCI at the time of transfer will be amortized over the remaining life of the underlying security as an adjustment to the yield on those securities. Securities transferred with losses included in AOCI continue to be included in management’s assessment for impairment for each individual security. There were no securities transferred from AFS to HTM during the three months ended March 31, 2021 or the year ended December 31, 2020. The accrued interest receivable on our debt securities is excluded from the credit loss estimate and is included in interest receivable on our consolidated balance sheets. As of March 31, 2021, accrued interest receivable on AFS and HTM debt securities totaled $13.4 million and $259,000, respectively. As of December 31, 2020, accrued interest receivable on AFS and HTM debt securities totaled $22.0 million and $298,000, respectively. No HTM debt securities were past-due or on nonaccrual status as of March 31, 2021 or December 31, 2020. The following table reflects interest income recognized on securities for the periods presented (in thousands): Three Months Ended 2021 2020 U.S. Treasury $ 37 $ — State and political subdivisions 10,406 6,625 Other stocks and bonds 845 93 MBS 6,088 11,534 Total interest income on securities $ 17,376 $ 18,252 There was a $2.0 million net realized gain from the AFS securities portfolio for the three months ended March 31, 2021, which consisted of $2.1 million in realized gains and $52,000 in realized losses. There was a $5.5 million net realized gain from the AFS securities portfolio for the three months ended March 31, 2020, which consisted of $5.6 million in realized gains and $10,000 in realized losses. There were no sales from the HTM portfolio during the three months ended March 31, 2021 or 2020. We calculate realized gains and losses on sales of securities under the specific identification method. Expected maturities on our securities may differ from contractual maturities because issuers may have the right to call or prepay obligations. MBS are presented in total by category since MBS are typically issued with stated principal amounts and are backed by pools of mortgages that have loans with varying maturities. The characteristics of the underlying pool of mortgages, such as fixed-rate or adjustable-rate, as well as prepayment risk, are passed on to the security holder. The term of a mortgage-backed pass-through security thus approximates the term of the underlying mortgages and can vary significantly due to prepayments. The amortized cost and estimated fair value of AFS and HTM securities at March 31, 2021, are presented below by contractual maturity (in thousands): March 31, 2021 Amortized Cost Fair Value AVAILABLE FOR SALE Investment securities: Due in one year or less $ 1,036 $ 1,061 Due after one year through five years 32,542 33,937 Due after five years through ten years 93,914 96,177 Due after ten years 1,535,281 1,595,730 1,662,773 1,726,905 MBS: 785,340 820,019 Total $ 2,448,113 $ 2,546,924 March 31, 2021 Amortized Cost Fair Value HELD TO MATURITY Investment securities: Due in one year or less $ 120 $ 121 Due after one year through five years 509 514 Due after five years through ten years 279 282 Due after ten years — — 908 917 MBS: 97,251 103,260 Total $ 98,159 $ 104,177 Equity Investments Equity investments on our consolidated balance sheets include Community Reinvestment Act funds with a readily determinable fair value as well as equity investments without readily determinable fair values. At March 31, 2021 and December 31, 2020, we had equity investments recorded in our consolidated balance sheets of $11.8 million and $11.9 million, respectively. Any realized and unrealized gains and losses on equity investments are reported in income. Equity investments without readily determinable fair values are recorded at cost less impairment, if any. The following is a summary of unrealized and realized gains and losses on equity investments recognized in other noninterest income in the consolidated statements of income during the periods presented (in thousands): Three Months Ended 2021 2020 Net (losses) gains recognized during the period on equity investments $ (107) $ 53 Less: Net gains recognized during the period on equity investments sold during the period — — Unrealized (losses) gains recognized during the reporting period on equity investments held at the reporting date $ (107) $ 53 Equity investments are assessed quarterly for other-than-temporary impairment. Based upon that evaluation, management does not consider any of our equity investments to be other-than-temporarily impaired at March 31, 2021. FHLB Stock Our FHLB stock, which has limited marketability, is carried at cost and is assessed quarterly for other-than-temporary impairment. Based upon evaluation by management at March 31, 2021, our FHLB stock was not impaired and thus was not considered to be other-than-temporarily impaired.

Loans and Allowance for Loan Lo

Loans and Allowance for Loan Losses	3 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Loans and Allowance for Loan Losses	Loans and Allowance for Loan Losses Loans in the accompanying consolidated balance sheets are classified as follows (in thousands): March 31, 2021 December 31, 2020 Real estate loans: Construction $ 605,677 $ 581,941 1-4 family residential 700,430 719,952 Commercial 1,348,551 1,295,746 Commercial loans 564,745 557,122 Municipal loans 406,377 409,028 Loans to individuals 90,818 93,990 Total loans 3,716,598 3,657,779 Less: Allowance for loan losses 41,454 49,006 Net loans $ 3,675,144 $ 3,608,773 Paycheck Protection Program Loans In April 2020, we began originating loans to qualified small businesses under the PPP administered by the SBA under the provisions of the CARES Act. Loans covered by the PPP may be eligible for loan forgiveness for certain costs incurred related to payroll, group health care benefit costs and qualifying mortgage, rent and utility payments. The remaining loan balance after forgiveness of any amount is still fully guaranteed by the SBA. On December 27, 2020, the Economic Aid Act was signed into law. This second coronavirus relief package granted additional funds for a new round of PPP loans. Additionally, it expanded the eligibility for loans and allowed certain businesses to request a second loan. In return for processing and booking a PPP loan, the SBA paid lenders a processing fee tiered by the size of the loan. These loans are included in commercial loans with an amortized cost basis at March 31, 2021 and December 31, 2020 of $220.9 million and $214.8 million, respectively. Construction Real Estate Loans Our construction loans are collateralized by property located primarily in or near the market areas we serve. A number of our construction loans will be owner occupied upon completion. Construction loans for non-owner occupied projects are financed, but these typically have cash flows from leases with tenants, secondary sources of repayment, and in some cases, additional collateral. Our construction loans have both adjustable and fixed interest rates during the construction period. Construction loans to individuals are typically priced and made with the intention of granting the permanent loan on the completed property. Speculative and commercial construction loans are subject to underwriting standards similar to that of the commercial portfolio. Owner occupied 1-4 family residential construction loans are subject to the underwriting standards of the permanent loan. 1-4 Family Residential Real Estate Loans Residential loan originations are generated by our loan officers, in-house origination staff, marketing efforts, present customers, walk-in customers and referrals from real estate agents and builders. We focus our lending efforts primarily on the origination of loans secured by first mortgages on owner occupied 1-4 family residences. Substantially all of our 1-4 family residential originations are secured by properties located in or near our market areas. Our 1-4 family residential loans generally have maturities ranging from five Underwriting for 1-4 family residential loans includes debt-to-income analysis, credit history analysis, appraised value and down payment considerations. Changes in the market value of real estate can affect the potential losses in the portfolio. Commercial Real Estate Loans Commercial real estate loans as of March 31, 2021 consisted of $1.25 billion of owner and non-owner occupied real estate, $81.6 million of loans secured by multi-family properties and $15.0 million of loans secured by farmland. Commercial real estate loans primarily include loans collateralized by retail, commercial office buildings, multi-family residential buildings, medical facilities and offices, senior living, assisted living and skilled nursing facilities, warehouse facilities, hotels and churches. In determining whether to originate commercial real estate loans, we generally consider such factors as the financial condition of the borrower and the debt service coverage of the property. Commercial real estate loans are made at both fixed and adjustable interest rates for terms generally up to 20 years. Commercial Loans Our commercial loans are diversified loan types including short-term working capital loans for inventory and accounts receivable and short- and medium-term loans for equipment or other business capital expansion. In our commercial loan underwriting, we assess the creditworthiness, ability to repay and the value and liquidity of the collateral being offered. Terms of commercial loans are generally commensurate with the useful life of the collateral offered. Municipal Loans We make loans to municipalities and school districts primarily throughout the state of Texas, with a small percentage originating outside of the state. The majority of the loans to municipalities and school districts have tax or revenue pledges and in some cases are additionally supported by collateral. Municipal loans made without a direct pledge of taxes or revenues are usually made based on some type of collateral that represents an essential service. Lending money directly to these municipalities allows us to earn a higher yield than we could if we purchased municipal securities for similar durations. Loans to Individuals Substantially all originations of our loans to individuals are made to consumers in our market areas. The majority of loans to individuals are collateralized by titled equipment, which are primarily automobiles. Loan terms vary according to the type and value of collateral, length of contract and creditworthiness of the borrower. The underwriting standards we employ for consumer loans include an application, a determination of the applicant’s payment history on other debts, with the greatest weight being given to payment history with us and an assessment of the borrower’s ability to meet existing obligations and payments on the proposed loan. Although creditworthiness of the applicant is a primary consideration, the underwriting process also includes a comparison of the value of the collateral, if any, in relation to the proposed loan amount. Most of our loans to individuals are collateralized, which management believes assists in limiting our exposure. Credit Quality Indicators We categorize loans into risk categories on an ongoing basis based on relevant information about the ability of borrowers to service their debt such as: current financial information, historical payment experience, credit documentation, public information and current economic trends, among other factors. We use the following definitions for risk ratings: • Pass (Rating 1 – 4) – This rating is assigned to all satisfactory loans. This category, by definition, consists of acceptable credit. Credit and collateral exceptions should not be present, although their presence would not necessarily prohibit a loan from being rated Pass, if deficiencies are in the process of correction. These loans are not included in the Watch List. • Pass Watch (Rating 5) – These loans require some degree of special treatment, but not due to credit quality. This category does not include loans specially mentioned or adversely classified; however, particular attention is warranted to characteristics such as: ▪ A lack of, or abnormally extended payment program; ▪ A heavy degree of concentration of collateral without sufficient margin; ▪ A vulnerability to competition through lesser or extensive financial leverage; and ▪ A dependence on a single or few customers or sources of supply and materials without suitable substitutes or alternatives. • Special Mention (Rating 6) – A Special Mention loan has potential weaknesses that deserve management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the loan or in our credit position at some future date. Special Mention loans are not adversely classified and do not expose us to sufficient risk to warrant adverse classification. • Substandard (Rating 7) – Substandard loans are inadequately protected by the current sound worth and paying capacity of the obligor or of the collateral pledged, if any. Loans so classified must have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that the Bank will sustain some loss if the deficiencies are not corrected. • Doubtful (Rating 8) – Loans classified as Doubtful have all the weaknesses inherent in those classified Substandard with the added characteristic that the weaknesses make collection or liquidation, in full, on the basis of currently known facts, conditions and values, highly questionable and improbable. The following tables set forth the amortized cost basis by class of financing receivable and credit quality indicator for the periods presented (in thousands): March 31, 2021 Term Loans Amortized Cost Basis by Origination Year Revolving Loans Amortized Cost Basis Total 2021 2020 2019 2018 2017 Prior Construction real estate: Pass $ 26,255 $ 160,527 $ 182,708 $ 75,258 $ 33,261 $ 8,877 $ 118,479 $ 605,365 Pass watch — — — — — 22 — 22 Special mention — — — — — — — — Substandard — — — — — 54 — 54 Doubtful — — — 59 — 177 — 236 Total construction real estate $ 26,255 $ 160,527 $ 182,708 $ 75,317 $ 33,261 $ 9,130 $ 118,479 $ 605,677 1-4 family residential real estate: Pass $ 39,457 $ 151,235 $ 104,065 $ 63,864 $ 46,692 $ 283,115 $ 2,506 $ 690,934 Pass watch — — — — — 823 — 823 Special mention — — — — — 65 — 65 Substandard 10 1,684 — — 943 5,289 94 8,020 Doubtful — 14 — 135 34 405 — 588 Total 1-4 family residential real estate $ 39,467 $ 152,933 $ 104,065 $ 63,999 $ 47,669 $ 289,697 $ 2,600 $ 700,430 Commercial real estate: Pass $ 138,805 $ 236,874 $ 285,638 $ 110,462 $ 181,077 $ 247,524 $ 6,857 $ 1,207,237 Pass watch — — — 23,272 37,938 5,472 — 66,682 Special mention 24,142 577 8,883 7,002 138 12,245 — 52,987 Substandard 2,105 4,631 — 1,956 63 12,756 — 21,511 Doubtful — — — — — 134 — 134 Total commercial real estate $ 165,052 $ 242,082 $ 294,521 $ 142,692 $ 219,216 $ 278,131 $ 6,857 $ 1,348,551 Commercial loans: Pass $ 108,205 $ 221,819 $ 41,605 $ 17,819 $ 6,368 $ 8,280 $ 146,516 $ 550,612 Pass watch 43 2,313 1,199 2,004 1,487 — 378 7,424 Special mention 280 — 718 416 36 385 320 2,155 Substandard 185 454 989 481 2 — 1,486 3,597 Doubtful — 382 95 449 31 — — 957 Total commercial loans $ 108,713 $ 224,968 $ 44,606 $ 21,169 $ 7,924 $ 8,665 $ 148,700 $ 564,745 Municipal loans: Pass $ 14,748 $ 69,822 $ 66,741 $ 32,166 $ 59,756 $ 163,144 $ — $ 406,377 Pass watch — — — — — — — — Special mention — — — — — — — — Substandard — — — — — — — — Doubtful — — — — — — — — Total municipal loans $ 14,748 $ 69,822 $ 66,741 $ 32,166 $ 59,756 $ 163,144 $ — $ 406,377 Loans to individuals: Pass $ 12,798 $ 39,592 $ 20,715 $ 8,079 $ 3,672 $ 2,079 $ 3,521 $ 90,456 Pass watch — — — — — — — — Special mention — — — 47 — — 4 51 Substandard — 19 34 22 27 10 — 112 Doubtful — 67 — 5 44 83 — 199 Total loans to individuals $ 12,798 $ 39,678 $ 20,749 $ 8,153 $ 3,743 $ 2,172 $ 3,525 $ 90,818 Total loans $ 367,033 $ 890,010 $ 713,390 $ 343,496 $ 371,569 $ 750,939 $ 280,161 $ 3,716,598 December 31, 2020 Term Loans Amortized Cost Basis by Origination Year Revolving Loans Amortized Cost Basis Total 2020 2019 2018 2017 2016 Prior Construction real estate: Pass $ 155,693 $ 180,536 $ 76,090 $ 55,636 $ 3,191 $ 8,297 $ 101,793 $ 581,236 Pass watch — — — — 23 — — 23 Special mention — — — — — — — — Substandard — 382 62 — — 58 — 502 Doubtful — — — — — 180 — 180 Total construction real estate $ 155,693 $ 180,918 $ 76,152 $ 55,636 $ 3,214 $ 8,535 $ 101,793 $ 581,941 1-4 family residential real estate: Pass $ 154,003 $ 114,063 $ 70,621 $ 55,557 $ 57,680 $ 255,003 $ 2,833 $ 709,760 Pass watch — — — — 267 564 — 831 Special mention — — — — — 10 — 10 Substandard 1,473 — 135 427 1,588 5,134 96 8,853 Doubtful — — — 36 103 359 — 498 Total 1-4 family residential real estate $ 155,476 $ 114,063 $ 70,756 $ 56,020 $ 59,638 $ 261,070 $ 2,929 $ 719,952 Commercial real estate: Pass $ 270,087 $ 307,161 $ 143,177 $ 162,180 $ 98,828 $ 179,919 $ 6,957 $ 1,168,309 Pass watch — — 3,153 40,125 1,696 2,582 — 47,556 Special mention 4,555 33,020 7,041 140 4,531 7,850 — 57,137 Substandard 7,542 — 2,097 65 704 12,282 — 22,690 Doubtful — — — — — 54 — 54 Total commercial real estate $ 282,184 $ 340,181 $ 155,468 $ 202,510 $ 105,759 $ 202,687 $ 6,957 $ 1,295,746 Commercial loans: Pass $ 313,688 $ 47,446 $ 20,386 $ 7,505 $ 3,392 $ 6,142 $ 140,018 $ 538,577 Pass watch 2,599 1,318 2,410 1,981 — — 370 8,678 Special mention 304 809 433 39 286 265 455 2,591 Substandard 405 1,081 473 7 — — 4,417 6,383 Doubtful 310 53 475 54 1 — — 893 Total commercial loans $ 317,306 $ 50,707 $ 24,177 $ 9,586 $ 3,679 $ 6,407 $ 145,260 $ 557,122 Municipal loans: Pass $ 72,542 $ 68,132 $ 33,735 $ 61,170 $ 25,387 $ 148,062 $ — $ 409,028 Pass watch — — — — — — — — Special mention — — — — — — — — Substandard — — — — — — — — Doubtful — — — — — — — — Total municipal loans $ 72,542 $ 68,132 $ 33,735 $ 61,170 $ 25,387 $ 148,062 $ — $ 409,028 Loans to individuals: Pass $ 46,722 $ 25,302 $ 10,132 $ 4,716 $ 1,867 $ 917 $ 3,900 $ 93,556 Pass watch — — — — — — — — Special mention — — 51 — — — 4 55 Substandard 6 35 28 30 9 11 1 120 Doubtful 73 20 6 55 81 24 — 259 Total loans to individuals $ 46,801 $ 25,357 $ 10,217 $ 4,801 $ 1,957 $ 952 $ 3,905 $ 93,990 Total loans $ 1,030,002 $ 779,358 $ 370,505 $ 389,723 $ 199,634 $ 627,713 $ 260,844 $ 3,657,779 The following tables present the aging of the amortized cost basis in past due loans by class of loans (in thousands): March 31, 2021 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days Past Due Total Past Due Current Total Real estate loans: Construction $ 1,130 $ — $ — $ 1,130 $ 604,547 $ 605,677 1-4 family residential 5,321 614 486 6,421 694,009 700,430 Commercial 4,676 — — 4,676 1,343,875 1,348,551 Commercial loans 1,507 245 641 2,393 562,352 564,745 Municipal loans — — — — 406,377 406,377 Loans to individuals 418 30 3 451 90,367 90,818 Total $ 13,052 $ 889 $ 1,130 $ 15,071 $ 3,701,527 $ 3,716,598 December 31, 2020 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days Total Past Due Current Total Real estate loans: Construction $ 95 $ 14 $ 444 $ 553 $ 581,388 $ 581,941 1-4 family residential 7,872 2,469 2,830 13,171 706,781 719,952 Commercial 467 315 86 868 1,294,878 1,295,746 Commercial loans 1,423 4,516 323 6,262 550,860 557,122 Municipal loans 64 — — 64 408,964 409,028 Loans to individuals 519 123 27 669 93,321 93,990 Total $ 10,440 $ 7,437 $ 3,710 $ 21,587 $ 3,636,192 $ 3,657,779 The following table sets forth the amortized cost basis of nonperforming assets for the periods presented (in thousands): March 31, 2021 December 31, 2020 Nonaccrual loans: Real estate loans: Construction $ 248 $ 640 1-4 family residential 1,929 3,922 Commercial 1,229 1,269 Commercial loans 1,682 1,592 Loans to individuals 226 291 Total nonaccrual loans (1) 5,314 7,714 Accruing loans past due more than 90 days — — TDR loans 9,641 9,646 OREO 412 106 Repossessed assets — 14 Total nonperforming assets $ 15,367 $ 17,480 (1) Includes $889,000 and $976,000 of restructured loans as of March 31, 2021 and December 31, 2020, respectively. We reversed $18,000 and $121,000 of interest income on nonaccrual loans during the three months ended March 31, 2021 and 2020, respectively. We had $1.6 million and $2.2 million of loans on nonaccrual for which there was no related allowance for credit losses as of March 31, 2021 and December 31, 2020, respectively. Collateral-dependent loans are loans that we expect the repayment to be provided substantially through the operation or sale of the collateral of the loan and we have determined that the borrower is experiencing financial difficulty. In such cases, expected credit losses are based on the fair value of the collateral at the measurement date, adjusted for selling costs. As of March 31, 2021 and December 31, 2020, we had $11.2 million and $11.5 million, respectively, of collateral-dependent loans, secured mainly by real estate and equipment. There have been no significant changes to the collateral that secures the collateral-dependent assets. Foreclosed assets include OREO and repossessed assets. For 1-4 family residential real estate properties, a loan is recognized as a foreclosed property once legal title to the real estate property has been received upon completion of foreclosure or the borrower has conveyed all interest in the residential property through a deed in lieu of foreclosure. There were $234,000 and $1.2 million in loans secured by 1-4 family residential properties for which formal foreclosure proceedings were in process as of March 31, 2021 and December 31, 2020, respectively. Troubled Debt Restructurings The restructuring of a loan is considered a TDR if both (i) the borrower is experiencing financial difficulties and (ii) the creditor has granted a concession. Concessions may include interest rate reductions or below market interest rates, restructuring amortization schedules and other actions intended to minimize potential losses. We may provide a combination of concessions which may include an extension of the amortization period, interest rate reduction and/or converting the loan to interest-only for a limited period of time. In response to the impact of the COVID-19 pandemic on the economy, the CARES Act was signed into law. Under the CARES Act, banks may elect to deem that loan modifications do not result in TDRs if they are: (1) related to COVID-19; (2) executed on a loan that was not more than 30 days past due as of December 31, 2019; and (3) executed between March 1, 2020, and the earlier of (A) 60 days after the date of termination of the national emergency declaration or (B) December 31, 2020. The Economic Aid Act extended this relief to the earlier of 60 days after the national emergency termination date or January 1, 2022. Additionally, in accordance with the Interagency Statement on Loan Modifications and Reporting for Financial Institutions Working with Customers Affected by the Coronavirus (Revised), other short-term modifications made on a good faith basis in response to COVID-19 to borrowers who were current prior to any relief are not TDRs under ASC Subtopic 310-40. This includes 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. Loans modified under this guidance are not considered TDRs and as such are not identified in the table below. At March 31, 2021 and December 31, 2020, we had outstanding loans with payment deferrals, generally for up to three months, totaling $1.7 million and $47.2 million, respectively. The following tables set forth the recorded balance of loans considered to be TDRs that were restructured and the type of concession by class of loans during the periods presented (dollars in thousands): Three Months Ended March 31, 2021 Extend Amortization Period Interest Rate Reductions Combination Total Modifications Number of Loans Real estate loans: 1-4 family residential $ — $ — $ 130 $ 130 2 Commercial loans — — 18 18 1 Total $ — $ — $ 148 $ 148 3 Three Months Ended March 31, 2020 Extend Amortization Period Interest Rate Reductions Combination Total Modifications Number of Loans Real estate loans: Commercial $ — $ — $ 59 $ 59 1 Commercial loans — — 3 3 1 Total $ — $ — $ 62 $ 62 2 Interest continues to be charged on principal balances outstanding during the extended term. Therefore, the financial effects of the recorded investment of loans restructured as TDRs during the three months ended March 31, 2021 and 2020 were not significant. Generally, the loans identified as TDRs were previously reported as impaired loans prior to restructuring, and therefore, the modification did not impact our determination of the allowance for loans losses. On an ongoing basis, the performance of the TDRs is monitored for subsequent payment default. Payment default for TDRs is recognized when the borrower is 90 days or more past due. For the three months ended March 31, 2021, and 2020 the amount of TDRs in default was not significant. Payment defaults for TDRs did not significantly impact the determination of the allowance for loan losses in the periods presented. At March 31, 2021 and 2020, there were no commitments to lend additional funds to borrowers whose terms had been modified in TDRs. Allowance for Loan Losses In accordance with ASC 326, the allowance for credit losses on loans is estimated and recognized upon origination of the loan based on expected credit losses. The CECL model uses historical experience and current conditions for homogeneous pools of loans, and reasonable and supportable forecasts about future events. The impact of varying economic conditions and portfolio stress factors are a component of the credit loss models applied to each portfolio. Reserve factors are specific to the loan segments that share similar risk characteristics based on the probability of default assumptions and loss given default assumptions, over the contractual term. The forecasted periods gradually mean-revert to the long-run trend based upon historical data. Management evaluates the economic data points used in the Moody’s forecasting scenarios on a quarterly basis to determine the most appropriate impact to the various portfolio characteristics based on management’s view and applies weighting to various forecasting scenarios as deemed appropriate based on known and expected economic activities. Management also considers and may apply relevant qualitative factors, not previously considered, to determine the appropriate allowance level. The use of the CECL model includes significant judgment by management and may differ from those of our peers due to different historical loss patterns, economic forecasts, and the length of time of the reasonable and supportable forecast period and reversion period. We utilize Moody’s Analytics economic forecast scenarios and assign probability weighting to those scenarios which best reflect management’s views on the economic forecast. The probability weighting and scenarios utilized for the estimate of the allowance were generally reflective of an improved economic forecast based on known and knowable information as of March 31, 2021. When determining the appropriate allowance for credit losses on our loan portfolio, our commercial construction and real estate loans, commercial loans and municipal loans utilize the probability of default/loss given default discounted cash flow approach. Reserves on these loans are based upon risk factors including the loan type and structure, collateral type, leverage ratio, refinancing risk and origination quality, among others. Our consumer construction real estate loans, 1-4 family residential loans and our loans to individuals use a loss rate based upon risk factors including loan types, origination year and credit scores. PPP loans are fully guaranteed by the SBA and therefore do not have an associated allowance. Loans evaluated collectively in a pool are monitored to ensure they continue to exhibit similar risk characteristics with other loans in the pool. If a loan does not share similar risk characteristics with other loans, expected credit losses for that loan are evaluated individually. The following tables detail activity in the allowance for loan losses by portfolio segment for the periods presented (in thousands): Three Months Ended March 31, 2021 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Balance at beginning of period $ 6,490 $ 2,270 $ 35,709 $ 4,107 $ 46 $ 384 $ 49,006 Loans charged-off — (73) — (319) — (403) (795) Recoveries of loans charged-off 1 55 — 282 — 284 622 Net loans (charged-off) recovered 1 (18) — (37) — (119) (173) Provision for (reversal of) loan losses 1,710 256 (8,473) (962) — 90 (7,379) Balance at end of period $ 8,201 $ 2,508 $ 27,236 $ 3,108 $ 46 $ 355 $ 41,454 Three Months Ended March 31, 2020 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Balance at beginning of period $ 3,539 $ 3,833 $ 9,572 $ 6,351 $ 570 $ 932 $ 24,797 Impact of CECL adoption - cumulative effect adjustment 2,968 (1,447) 7,730 (3,532) (522) (125) 5,072 Impact of CECL adoption - purchased loans with credit deterioration (15) (6) 333 (22) — (59) 231 Loans charged-off (33) (54) (21) (296) — (591) (995) Recoveries of loans charged-off 11 4 69 74 — 293 451 Net loans (charged-off) recovered (22) (50) 48 (222) — (298) (544) Provision for (reversal of) loan losses (1) 3,184 310 18,437 1,944 (1) 208 24,082 Balance at end of period $ 9,654 $ 2,640 $ 36,120 $ 4,519 $ 47 $ 658 $ 53,638 (1) The increase in the provision for credit losses during 2020 was primarily due to the economic impact of COVID-19 on macroeconomic factors used in the CECL model. The accrued interest receivable on our loan receivables is excluded from the allowance for credit loss estimate and is included in interest receivable on our consolidated balance sheets. As of March 31, 2021 and December 31, 2020, the accrued interest on our loan portfolio was $13.8 million and $16.4 million, respectively.

Borrowing Arrangements

Borrowing Arrangements	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Borrowing Arrangements	Borrowing Arrangements Information related to borrowings is provided in the table below (dollars in thousands): March 31, 2021 December 31, 2020 Other borrowings: Balance at end of period $ 22,315 $ 23,172 Average amount outstanding during the period (1) 23,522 91,940 Maximum amount outstanding during the period (2) 24,549 219,259 Weighted average interest rate during the period (3) 0.2 % 0.4 % Interest rate at end of period (4) 0.2 % 0.1 % FHLB borrowings: Balance at end of period $ 665,530 $ 832,527 Average amount outstanding during the period (1) 727,513 1,032,269 Maximum amount outstanding during the period (2) 723,584 1,274,370 Weighted average interest rate during the period (3) 1.1 % 1.1 % Interest rate at end of period (4) 1.1 % 1.0 % (1) The average amount outstanding during the period was computed by dividing the total daily outstanding principal balances by the number of days in the period. (2) The maximum amount outstanding at any month-end during the period. (3) The weighted average interest rate during the period was computed by dividing the actual interest expense (annualized for interim periods) by the average amount outstanding during the period. The weighted average interest rate on the FHLB borrowings includes the effect of interest rate swaps. (4) Stated rate. Maturities of the obligations associated with our borrowing arrangements based on scheduled repayments at March 31, 2021 are as follows (in thousands): Payments Due by Period Less than 1-2 Years 2-3 Years 3-4 Years 4-5 Years Thereafter Total Other borrowings $ 22,315 $ — $ — $ — $ — $ — $ 22,315 FHLB borrowings 661,659 687 717 748 775 944 665,530 Total obligations $ 683,974 $ 687 $ 717 $ 748 $ 775 $ 944 $ 687,845 Other borrowings include federal funds purchased, repurchase agreements and borrowings from the FRDW. Southside Bank has three unsecured lines of credit for the purchase of overnight federal funds at prevailing rates with Frost Bank, TIB – The Independent Bankers Bank and Comerica Bank for $40.0 million, $15.0 million and $7.5 million, respectively. There were no federal funds purchased at March 31, 2021 or December 31, 2020. To provide more liquidity in response to the economic impact of the COVID-19 pandemic, the Federal Reserve took steps to encourage broader use of the discount window. At March 31, 2021, the amount of additional funding the Bank could obtain from the FRDW, collateralized by securities and PPP loans, was approximately $618.1 million. There were no borrowings from the FRDW at March 31, 2021 or December 31, 2020. Southside Bank has a $5.0 million line of credit with Frost Bank to be used to issue letters of credit, and at March 31, 2021, the line had one outstanding letter of credit for $91,000. Southside Bank currently has no outstanding letters of credit from FHLB held as collateral for its public fund deposits. Southside Bank enters into sales of securities under repurchase agreements. These repurchase agreements totaled $22.3 million at March 31, 2021 and $23.2 million at December 31, 2020, and had maturities of less than one year. Repurchase agreements are secured by investment and MBS securities and are stated at the amount of cash received in connection with the transaction. FHLB borrowings represent borrowings with fixed interest rates ranging from 0.08% to 4.799% and with remaining maturities of five days to 7.3 years at March 31, 2021. FHLB borrowings may be collateralized by FHLB stock, nonspecified loans and/or securities. At March 31, 2021, the amount of additional funding Southside Bank could obtain from FHLB, collateralized by securities, FHLB stock and nonspecified loans and securities, was approximately $1.25 billion, net of FHLB stock purchases required. Southside Bank has entered into various variable rate agreements and fixed rate short-term pay agreements with third-party financial institutions with rates tied to LIBOR. These agreements totaled $625.0 million at March 31, 2021 and $670.0 million at December 31, 2020. Six of the agreements have an interest rate tied to three-month LIBOR, and the remaining agreements have interest rates tied to one-month LIBOR. In connection with all of these agreements, Southside Bank also entered into various interest rate swap contracts that are treated as cash flow hedges under ASC Topic 815, “Derivatives and Hedging” that are expected to be effective in hedging the variability in future cash flows attributable to fluctuations in the underlying LIBOR interest rate. The interest rate swap contracts had a weighted average rate of 1.11% with a weighted average maturity of 3.8 years at March 31, 2021. Refer to “Note 9 – Derivative Financial Instruments and Hedging Activities” in our consolidated financial statements included in this report for a detailed description of our hedging policy and methodology related to derivative instruments.

Long-term Debt

Long-term Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Long-term Debt	Long-term Debt Information related to our long-term debt is summarized as follows for the periods presented (in thousands): March 31, 2021 December 31, 2020 Subordinated notes: (1) 3.875% Subordinated notes, net of unamortized debt issuance costs (2) $ 98,469 $ 98,497 5.50% Subordinated notes, net of unamortized debt issuance costs (3) 98,799 98,754 Total Subordinated notes 197,268 197,251 Trust preferred subordinated debentures: (4) Southside Statutory Trust III, net of unamortized debt issuance costs (5) 20,564 20,563 Southside Statutory Trust IV 23,196 23,196 Southside Statutory Trust V 12,887 12,887 Magnolia Trust Company I 3,609 3,609 Total Trust preferred subordinated debentures 60,256 60,255 Total Long-term debt $ 257,524 $ 257,506 (1) This debt consists of subordinated notes with a remaining maturity greater than one year that qualify under the risk-based capital guidelines as Tier 2 capital, subject to certain limitations. (2) The unamortized discount and debt issuance costs reflected in the carrying amount of the subordinated notes totaled approximately $1.5 million at March 31, 2021 and December 31, 2020. (3) The unamortized discount and debt issuance costs reflected in the carrying amount of the subordinated notes totaled approximately $1.2 million at March 31, 2021 and December 31, 2020. (4) This debt consists of trust preferred securities that qualify under the risk-based capital guidelines as Tier 1 capital, subject to certain limitations. (5) The unamortized debt issuance costs reflected in the carrying amount of the Southside Statutory Trust III junior subordinated debentures totaled $55,000 at March 31, 2021 and $56,000 at December 31, 2020. As of March 31, 2021, the details of the subordinated notes and the trust preferred subordinated debentures are summarized below (dollars in thousands): Date Issued Amount Issued Fixed or Floating Rate Interest Rate Maturity Date 3.875% Subordinated Notes November 6, 2020 $ 100,000 Fixed-to-Floating 3.875% November 15, 2030 5.50% Subordinated Notes September 19, 2016 $ 100,000 Fixed-to-Floating 5.50% September 30, 2026 Southside Statutory Trust III September 4, 2003 $ 20,619 Floating 3 month LIBOR + 2.94% September 4, 2033 Southside Statutory Trust IV August 8, 2007 $ 23,196 Floating 3 month LIBOR + 1.30% October 30, 2037 Southside Statutory Trust V August 10, 2007 $ 12,887 Floating 3 month LIBOR + 2.25% September 15, 2037 Magnolia Trust Company I (1) October 10, 2007 $ 3,609 Floating 3 month LIBOR + 1.80% November 23, 2035 (1) On October 10, 2007, as part of an acquisition we assumed $3.6 million of floating rate junior subordinated debentures issued in 2005 to Magnolia Trust Company I. On September 19, 2016, the Company issued $100.0 million in aggregate principal amount of fixed-to-floating rate subordinated notes that mature on September 30, 2026. This debt initially bears interest at a fixed rate of 5.50% through September 29, 2021 and thereafter, adjusts quarterly at a floating rate equal to three-month LIBOR plus 429.7 basis points. The proceeds from the sale of the subordinated notes were used for general corporate purposes, which included advances to the Bank to finance its activities.

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2021
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Employee Benefit Plans	Employee Benefit Plans The components of net periodic benefit cost (income) related to our employee benefit plans are as follows (in thousands): Three Months Ended March 31, Defined Benefit Defined Benefit Pension Plan Acquired Restoration 2021 2020 2021 2020 2021 2020 Service cost $ — $ 423 $ — $ — $ — $ 85 Interest cost 628 837 24 41 121 160 Expected return on assets (1,437) (1,668) (58) (84) — — Net loss amortization 520 533 3 2 118 193 Prior service (credit) cost amortization — (3) — — — 2 Net periodic benefit (income) cost $ (289) $ 122 $ (31) $ (41) $ 239 $ 440 Prior to the freeze of all future benefit accruals and accrual of benefit service as of December 31, 2020, the service cost component was recorded on our consolidated income statements as salaries and employee benefits in noninterest expense. All other components other than service costs are recorded in other noninterest expense.

Derivative Financial Instrument

Derivative Financial Instruments and Hedging Activities	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments and Hedging Activities	Derivative Financial Instruments and Hedging Activities Our hedging policy allows the use of interest rate derivative instruments to manage our exposure to interest rate risk or hedge specified assets and liabilities. These instruments may include interest rate swaps and interest rate caps and floors. All derivative instruments are carried on the balance sheet at their estimated fair value and are recorded in other assets or other liabilities, as appropriate. Derivative instruments may be designated as cash flow hedges of variable rate assets or liabilities, cash flow hedges of forecasted transactions, fair value hedges of a recognized asset or liability or as non-hedging instruments. Gains and losses on derivative instruments designated as cash flow hedges are recorded in AOCI to the extent they are effective. If the hedge is effective, the amount recorded in other comprehensive income is reclassified to earnings in the same periods that the hedged cash flows impact earnings. The ineffective portion of changes in fair value is reported in current earnings. Gains and losses on derivative instruments designated as fair value hedges, as well as the change in fair value on the hedged item, are recorded in interest income in the consolidated statements of income. Gains and losses due to changes in fair value of the interest rate swap agreements completely offset changes in the fair value of the hedged portion of the hedged item. For derivative instruments not designated as hedging instruments, the gain or loss is recognized in current earnings during the period of change. We have entered into certain interest rate swap contracts on specific variable rate agreements and fixed rate short-term pay agreements with third-party financial institutions. These interest rate swap contracts were designated as hedging instruments in cash flow hedges under ASC Topic 815. The objective of the interest rate swap contracts is to manage the expected future cash flows on $625.0 million of debt. The cash flows from the swap contracts are expected to be effective in hedging the variability in future cash flows attributable to fluctuations in the underlying LIBOR interest rate. In accordance with ASC Topic 815, if a hedging item is terminated prior to maturity for a cash settlement, the existing gain or loss within AOCI will continue to be reclassified into earnings during the period or periods in which the hedged forecasted transaction affects earnings unless it is probable the forecasted transaction will not occur by the end of the originally specified time period. These transactions are reevaluated on a monthly basis to determine if the hedged forecasted transactions are still probable of occurring. If at a subsequent evaluation, it is determined that the transactions will not occur, any related gains or losses recorded in AOCI are immediately recognized in earnings. From time to time, we may enter into certain interest rate swaps, cap and floor contracts that are not designated as hedging instruments. These interest rate derivative contracts relate to transactions in which we enter into an interest rate swap, cap or floor with a customer while concurrently entering into an offsetting interest rate swap, cap or floor with a third party financial institution. We agree to pay interest to the customer on a notional amount at a variable rate and receive interest from the customer on a similar notional amount at a fixed interest rate. At the same time, we agree to pay a third party financial institution the same fixed interest rate on the same notional amount and receive the same variable interest rate on the same notional amount. These interest rate derivative contracts allow our customers to effectively convert a variable rate loan to a fixed rate loan. The changes in the fair value of the underlying derivative contracts primarily offset each other and do not significantly impact our results of operations. We recognized swap fee income associated with these derivative contracts immediately based upon the difference in the bid/ask spread of the underlying transactions with the customer and the third party financial institution. The swap fee income is included in other noninterest income in our consolidated statements of income. At March 31, 2021 and December 31, 2020, net derivative liabilities included $19.1 million and $39.3 million, respectively, of cash collateral held by counterparties subject to master netting agreements. We had $1.3 million of cash collateral receivable that was not offset against derivative liabilities at March 31, 2021. The notional amounts of the derivative instruments represent the contractual cash flows pertaining to the underlying agreements. These amounts are not exchanged and are not reflected in the consolidated balance sheets. The fair value of the interest rate swaps are presented at net in other assets and other liabilities when a right of offset exists, based on transactions with a single counterparty that are subject to a legally enforceable master netting agreement. The following tables present the notional and estimated fair value amount of derivative positions outstanding (in thousands): March 31, 2021 December 31, 2020 Estimated Fair Value Estimated Fair Value Notional (1) Asset Derivative Liability Derivative Notional (1) Asset Derivative Liability Derivative Derivatives designated as hedging instruments Interest rate contracts: Swaps-Cash Flow Hedge-Financial institution counterparties $ 625,000 $ 2,145 $ 11,189 $ 670,000 $ — $ 21,635 Derivatives designated as non-hedging instruments Interest rate contracts: Swaps-Financial institution counterparties 217,655 910 10,980 152,280 — 18,537 Swaps-Customer counterparties 217,655 10,980 910 152,280 18,537 — Gross derivatives 14,035 23,079 18,537 40,172 Offsetting derivative assets/liabilities (3,055) (3,055) — — Cash collateral received/posted — (19,114) — (39,270) Net derivatives included in the consolidated balance sheets (2) $ 10,980 $ 910 $ 18,537 $ 902 (1) Notional amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the consolidated balance sheets. (2) Net derivative assets are included in other assets and net derivative liabilities are included in other liabilities on the consolidated balance sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and our credit risk. We had $1.3 million credit exposure related to interest rate swaps with financial institutions and $11.0 million related to interest rate swaps with customers at March 31, 2021. We had no credit exposure related to interest rate swaps with financial institutions and $18.5 million related to interest rate swaps with customers at December 31, 2020. The credit risk associated with customer transactions is partially mitigated as these are generally secured by the non-cash collateral securing the underlying transaction being hedged. The summarized expected weighted average remaining maturity of the notional amount of interest rate swaps and the weighted average interest rates associated with the amounts expected to be received or paid on interest rate swap agreements are presented below (dollars in thousands). Variable rates received on fixed pay swaps are based on one-month or three-month LIBOR rates in effect at March 31, 2021 and December 31, 2020: March 31, 2021 December 31, 2020 Weighted Average Weighted Average Notional Amount Remaining Maturity Receive Rate Pay Rate Notional Amount Remaining Maturity Receive Rate Pay Swaps-Cash Flow hedge Financial institution counterparties $ 625,000 3.8 0.14 % 1.11 % $ 670,000 3.8 0.17 % 1.12 % Swaps-Non-hedging Financial institution counterparties 217,655 11.0 0.52 % 2.43 % 152,280 9.8 0.50 % 2.57 % Customer counterparties 217,655 11.0 2.43 % 0.52 % 152,280 9.8 2.57 % 0.50 %

Fair Value Measurement

Fair Value Measurement	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement Fair value is the price that would be received upon the sale of an asset or paid to transfer a liability (exit price) in an orderly transaction between market participants. A fair value measurement assumes the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability is not adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets and liabilities; it is not a forced transaction. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact and (iv) willing to transact. Valuation techniques including the market approach, the income approach and/or the cost approach are utilized to determine fair value. Inputs to valuation techniques refer to the assumptions market participants would use in pricing the asset or liability. Valuation policies and procedures are determined by our investment department and reported to our ALCO for review. An entity must consider all aspects of nonperforming risk, including the entity’s own credit standing, when measuring fair value of a liability. Inputs may be observable, meaning those that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources, or unobservable, meaning those that reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. A fair value hierarchy for valuation inputs 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 - Unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. Level 2 Inputs - Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These might include quoted prices for similar assets or liabilities in active markets, 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, volatilities, prepayment speeds, credit risks, etc.) or inputs that are derived principally from or corroborated by market data by correlation or other means. Level 3 Inputs - Unobservable inputs for determining the fair values of assets or liabilities that reflect an entity’s own assumptions about the assumptions that market participants would use in pricing the assets or liabilities. Certain financial assets are measured at fair value in accordance with GAAP. Adjustments to the fair value of these assets usually result from the application of fair value accounting or write-downs of individual assets. A description of the valuation methodologies used for assets and liabilities measured at fair value, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below. Securities AFS and Equity Investments with readily determinable fair values – U.S. Treasury securities and equity investments with readily determinable fair values are reported at fair value utilizing Level 1 inputs. Other securities classified as AFS are reported at fair value utilizing Level 2 inputs. For these securities, we obtain fair value measurements from independent pricing services and obtain an understanding of the pricing methodologies used by these independent pricing services. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the bond’s terms and conditions, among other things, as stated in the pricing methodologies of the independent pricing services. We review and validate the prices supplied by the independent pricing services for reasonableness by comparison to prices obtained from, in some cases, two additional third-party sources. For securities where prices are outside a reasonable range, we further review those securities, based on internal ALCO approved procedures, to determine what a reasonable fair value measurement is for those securities, given available data. Derivatives – Derivatives are reported at fair value utilizing Level 2 inputs. We obtain fair value measurements from two sources including an independent pricing service and the counterparty to the derivatives designated as hedges. The fair value measurements consider observable data that may include dealer quotes, market spreads, the U.S. Treasury yield curve, live trading levels, trade execution data, credit information and the derivatives’ terms and conditions, among other things. We review the prices supplied by the sources for reasonableness. In addition, we obtain a basic understanding of their underlying pricing methodology. We validate prices supplied by the sources by comparison to one another. Certain nonfinancial assets and nonfinancial liabilities measured at fair value on a recurring basis include reporting units measured at fair value and tested for goodwill impairment. Certain financial assets and financial liabilities are measured at fair value on a nonrecurring basis, which means that the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (for example, when there is evidence of impairment). Financial assets and financial liabilities measured at fair value on a nonrecurring basis included foreclosed assets and collateral-dependent loans at March 31, 2021 and December 31, 2020. Foreclosed Assets – Foreclosed assets are initially recorded at fair value less costs to sell. The fair value measurements of foreclosed assets can include Level 2 measurement inputs such as real estate appraisals and comparable real estate sales information, in conjunction with Level 3 measurement inputs such as cash flow projections, qualitative adjustments and sales cost estimates. As a result, the categorization of foreclosed assets is Level 3 of the fair value hierarchy. In connection with the measurement and initial recognition of certain foreclosed assets, we may recognize charge-offs through the allowance for credit losses. Collateral-Dependent Loans (Impaired loans prior to the adoption of ASU 2016-13) – Certain loans may be reported at the fair value of the underlying collateral if repayment is expected substantially from the operation or sale of the collateral. Collateral values are estimated using Level 3 inputs based on customized discounting criteria or appraisals. At March 31, 2021 and December 31, 2020, the impact of the fair value of collateral-dependent loans was reflected in our allowance for loan losses. The fair value estimate of financial instruments for which quoted market prices are unavailable is dependent upon the assumptions used. Consequently, those estimates cannot be substantiated by comparison to independent markets and, in many cases, could not be realized in immediate settlement of the instruments. Accordingly, the aggregate fair value amounts presented in the fair value tables do not necessarily represent their underlying value. The following tables summarize assets measured at fair value on a recurring and nonrecurring basis segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands): Fair Value Measurements at the End of the Reporting Period Using March 31, 2021 Carrying Amount Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Recurring fair value measurements Investment securities: U.S. Treasury $ 42,477 $ 42,477 $ — $ — State and political subdivisions 1,591,645 — 1,591,645 — Other stocks and bonds 92,783 — 92,783 — MBS: (1) Residential 707,074 — 707,074 — Commercial 112,945 — 112,945 — Equity investments: Equity investments 5,988 5,988 — — Derivative assets: Interest rate swaps 14,035 — 14,035 — Total asset recurring fair value measurements $ 2,566,947 $ 48,465 $ 2,518,482 $ — Derivative liabilities: Interest rate swaps $ 23,079 $ — $ 23,079 $ — Total liability recurring fair value measurements $ 23,079 $ — $ 23,079 $ — Nonrecurring fair value measurements Foreclosed assets $ 412 $ — $ — $ 412 Collateral-dependent loans (2) 10,223 — — 10,223 Total asset nonrecurring fair value measurements $ 10,635 $ — $ — $ 10,635 Fair Value Measurements at the End of the Reporting Period Using December 31, 2020 Carrying Amount Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Recurring fair value measurements Investment securities: State and political subdivisions $ 1,580,594 $ — $ 1,580,594 $ — Other stocks and bonds 78,255 — 78,255 — MBS: (1) Residential 810,010 — 810,010 — Commercial 118,446 — 118,446 — Equity investments: Equity investments 6,094 6,094 — — Derivative assets: Interest rate swaps 18,537 — 18,537 — Total asset recurring fair value measurements $ 2,611,936 $ 6,094 $ 2,605,842 $ — Derivative liabilities: Interest rate swaps $ 40,172 $ — $ 40,172 $ — Total liability recurring fair value measurements $ 40,172 $ — $ 40,172 $ — Nonrecurring fair value measurements Foreclosed assets $ 120 $ — $ — $ 120 Collateral-dependent loans (2) 10,653 — — 10,653 Total asset nonrecurring fair value measurements $ 10,773 $ — $ — $ 10,773 (1) All MBS are issued and/or guaranteed by U.S. government agencies or U.S. GSEs. (2) Consists of individually evaluated loans. Loans for which the fair value of the collateral and commercial real estate fair value of the properties is less than cost basis are presented net of allowance. Losses on these loans represent charge-offs which are netted against the allowance for loan losses. Disclosure of fair value information about financial instruments, whether or not recognized in the balance sheet, is required when it is practicable to estimate that value. In cases where quoted market prices are not available, fair values are based on estimates using present value or other estimation techniques. Those techniques are significantly affected by the assumptions used, including the discount rate and estimates of future cash flows. Such techniques and assumptions, as they apply to individual categories of our financial instruments, are as follows: Cash and cash equivalents – The carrying amount for cash and cash equivalents is a reasonable estimate of those assets’ fair value. Investment and MBS HTM – Fair values for these securities are based on quoted market prices, where available. If quoted market prices are not available, fair values are based on quoted market prices for similar securities or estimates from independent pricing services. FHLB stock – The carrying amount of FHLB stock is a reasonable estimate of the fair value of those assets. Equity investments – The carrying value of equity investments without readily determinable fair values are measured at cost less impairment, if any, adjusted for observable price changes for an identical or similar investment of the same issuer. This carrying value is a reasonable estimate of the fair value of those assets. Loans receivable – We estimate the fair value of our loan portfolio to an exit price notion with adjustments for liquidity, credit and prepayment factors. Nonperforming loans continue to be estimated using discounted cash flow analyses or the underlying value of the collateral where applicable. Loans held for sale – The fair value of loans held for sale is determined based on expected proceeds, which are based on sales contracts and commitments. Deposit liabilities – The fair value of demand deposits, savings accounts and certain money market deposits is the amount on demand at the reporting date, which is the carrying value. Fair values for fixed rate CDs are estimated using a discounted cash flow calculation that applies interest rates currently being offered for deposits of similar remaining maturities. Other borrowings – Federal funds purchased generally have original terms to maturity of one day and repurchase agreements generally have terms of less than one year, and therefore both are considered short-term borrowings. Consequently, their carrying value is a reasonable estimate of fair value. FHLB borrowings – The fair value of these borrowings is estimated by discounting the future cash flows using rates at which borrowings would be made to borrowers with similar credit ratings and for the same remaining maturities. Subordinated notes – The fair value of the subordinated notes is estimated by discounting future cash flows using estimated rates at which long-term debt would be made to borrowers with similar credit ratings and for the remaining maturities. Trust preferred subordinated debentures – The fair value of the long-term debt is estimated by discounting future cash flows using estimated rates at which long-term debt would be made to borrowers with similar credit ratings and for the remaining maturities. The following tables present our financial assets and financial liabilities measured on a nonrecurring basis at both their respective carrying amounts and estimated fair value (in thousands): Estimated Fair Value March 31, 2021 Carrying Total Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 107,623 $ 107,623 $ 107,623 $ — $ — Investment securities: HTM, at carrying value 908 917 — 917 — MBS: HTM, at carrying value 97,251 103,260 — 103,260 — FHLB stock, at cost 18,754 18,754 — 18,754 — Equity investments 5,816 5,816 — 5,816 — Loans, net of allowance for loan losses 3,675,144 3,833,854 — — 3,833,854 Loans held for sale 2,615 2,615 — 2,615 — Financial liabilities: Deposits $ 5,092,643 $ 5,095,397 $ — $ 5,095,397 $ — Other borrowings 22,315 22,315 — 22,315 — FHLB borrowings 665,530 675,135 — 675,135 — Subordinated notes, net of unamortized debt issuance costs 197,268 198,103 — 198,103 — Trust preferred subordinated debentures, net of unamortized debt issuance costs 60,256 47,183 — 47,183 — Estimated Fair Value December 31, 2020 Carrying Total Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 108,408 $ 108,408 $ 108,408 $ — $ — Investment securities: HTM, at carrying value 907 920 — 920 — Mortgage-backed securities: HTM, at carrying value 108,091 117,278 — 117,278 — Federal Home Loan Bank stock, at cost 25,259 25,259 — 25,259 — Equity investments 5,811 5,811 — 5,811 — Loans, net of allowance for loan losses 3,608,773 3,784,291 — — 3,784,291 Loans held for sale 3,695 3,695 — 3,695 — Financial liabilities: Deposits $ 4,932,322 $ 4,936,188 $ — $ 4,936,188 $ — Other borrowings 23,172 23,172 — 23,172 — FHLB borrowings 832,527 854,865 — 854,865 — Subordinated notes, net of unamortized debt issuance costs 197,251 198,391 — 198,391 — Trust preferred subordinated debentures, net of unamortized debt issuance costs 60,255 51,993 — 51,993 —

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The income tax expense included in the accompanying consolidated statements of income consists of the following (in thousands): Three Months Ended 2021 2020 Current income tax expense $ 2,589 $ 5,554 Deferred income tax expense (benefit) 2,161 (5,075) Income tax expense $ 4,750 $ 479 The net deferred tax liability totaled $9.9 million at March 31, 2021 and $15.5 million at December 31, 2020. No valuation allowance was recorded at March 31, 2021 or December 31, 2020, as management believes it is more likely than not that all of the deferred tax asset items will be realized in future years. Unrecognized tax benefits were not material at March 31, 2021 or December 31, 2020.

Off-Balance-Sheet Arrangements,

Off-Balance-Sheet Arrangements, Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Off-Balance-Sheet Arrangements, Commitments and Contingencies	Off-Balance-Sheet Arrangements, Commitments and Contingencies Financial Instruments with Off-Balance-Sheet Risk . In the normal course of business, we are a party to certain financial instruments with off-balance-sheet risk to meet the financing needs of our customers. These off-balance-sheet instruments include commitments to extend credit and standby letters of credit. These instruments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount reflected in the financial statements. The contract or notional amounts of these instruments reflect the extent of involvement and exposure to credit loss that we have in these particular classes of financial instruments. The allowance for credit losses on these off-balance-sheet credit exposures is calculated using the same methodology as loans including a conversion or usage factor to anticipate ultimate exposure and expected losses and is included in other liabilities on our consolidated balance sheets. Allowance for off-balance-sheet credit exposures were as follows (in thousands): Three Months Ended 2021 2020 Balance at beginning of period $ 6,386 $ 1,455 Impact of CECL adoption — 4,840 Provision for (reversal of) off-balance-sheet credit exposures (2,770) 1,165 Balance at end of period $ 3,616 $ 7,460 Contractual commitments to extend credit are agreements to lend to a customer provided the terms established in the contract are met. Commitments to extend credit generally have fixed expiration dates and may require the payment of fees. Since some commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. Standby letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. These guarantees are primarily issued to support public and private borrowing arrangements. The credit risk involved in issuing letters of credit is essentially the same as that involved in commitments to extend credit and similarly do not necessarily represent future cash obligations. Financial instruments with off-balance-sheet risk were as follows (in thousands): March 31, 2021 December 31, 2020 Commitments to extend credit $ 811,574 $ 793,138 Standby letters of credit 10,825 13,658 Total $ 822,399 $ 806,796 We apply the same credit policies in making commitments to extend credit and standby letters of credit as we do for on-balance-sheet instruments. We evaluate each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if deemed necessary, upon extension of credit is based on management’s credit evaluation of the borrower. Collateral held varies but may include cash or cash equivalents, negotiable instruments, real estate, accounts receivable, inventory, oil, gas and mineral interests, property, plant and equipment. Leases . During the three months ended March 31, 2021, there was $1.1 million of operating lease right-of-use assets obtained in exchange for new operating lease liabilities, primarily due to one lease that commenced in January 2021 with an initial right-of-use asset of $1.1 million. There was $227,000 of operating lease right-of-use assets obtained in exchange for new operating lease liabilities for the three months ended March 31, 2020. Securities . In the normal course of business we buy and sell securities. At March 31, 2021, there were $23.5 million of unsettled trades to purchase securities and no unsettled trades to sell securities. At December 31, 2020, there were no unsettled trades to purchase securities and no unsettled trades to sell securities. Deposits . There were no unsettled issuances of brokered CDs at March 31, 2021 or December 31, 2020. Litigation . We are involved with various litigation in the normal course of business. Management, after consulting with our legal counsel, believes that any liability resulting from litigation will not have a material effect on our financial position, results of operations or liquidity.

Summary of Significant Accoun_2

Summary of Significant Accounting and Reporting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation In this report, the words “the Company,” “we,” “us,” and “our” refer to the combined entities of Southside Bancshares, Inc. and its subsidiaries, including Southside Bank. The words “Southside” and “Southside Bancshares” refer to Southside Bancshares, Inc. The words “Southside Bank” and “the Bank” refer to Southside Bank. The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, not all information required by GAAP for complete financial statements is included in these interim statements. In the opinion of management, all adjustments necessary for a fair presentation of such financial statements have been included. Such adjustments consisted only of normal recurring items. The preparation of these consolidated financial statements in accordance with GAAP requires the use of management’s estimates. These estimates are subjective in nature and involve matters of judgment. Actual amounts could differ from these estimates.
Accounting Changes and Reclassifications and Accounting Pronouncements	Accounting Changes and Reclassifications Certain prior period amounts may be reclassified to conform to current year presentation. Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” ASU 2020-04 is intended to provide relief for companies preparing for discontinuation of interest rates based on LIBOR. The ASU provides optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or other reference rates expected to be discontinued. ASU 2020-04 also provides for a one-time sale and/or transfer to AFS or trading to be made for HTM debt securities that both reference an eligible reference rate and were classified as HTM before January 1, 2020. ASU 2020-04 was effective for all entities as of March 12, 2020 and through December 31, 2022. Companies can apply the ASU as of the beginning of the interim period that includes March 12, 2020 or any date thereafter. The guidance requires companies to apply the guidance prospectively to contract modifications and hedging relationships while the one-time election to sell and/or transfer debt securities classified as HTM may be made any time after March 12, 2020. We have established an officer level committee to guide our transition from LIBOR and have begun efforts to transition to alternative rates consistent with industry timelines. We have identified products that utilize LIBOR and are implementing enhanced fallback language to facilitate the transition to alternative reference rates. We are evaluating existing systems and have begun offering new rates on a limited basis. ASU 2020-04 is not expected to have a material impact on our consolidated financial statements.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings per share on a basic and diluted basis	Earnings per share on a basic and diluted basis are calculated as follows (in thousands, except per share amounts): Three Months Ended 2021 2020 Basic and Diluted Earnings: Net income $ 34,091 $ 3,953 Basic weighted-average shares outstanding 32,829 33,691 Add: Stock awards 108 114 Diluted weighted-average shares outstanding 32,937 33,805 Basic earnings per share: Net income $ 1.04 $ 0.12 Diluted earnings per share: Net income $ 1.04 $ 0.12

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of accumulated other comprehensive income (loss) by component	The changes in accumulated other comprehensive income (loss) by component are as follows (in thousands): Three Months Ended March 31, 2021 Pension Plans Unrealized Gains (Losses) on Securities Unrealized Gains (Losses) on Derivatives Net Prior Net Gain (Loss) Total Beginning balance, net of tax $ 116,078 $ (17,091) $ 149 $ (30,056) $ 69,080 Other comprehensive income (loss): Other comprehensive (loss) income before reclassifications (48,979) 11,023 — — (37,956) Reclassification adjustments included in net income (1,587) 1,568 — 641 622 Income tax benefit (expense) 10,619 (2,644) — (135) 7,840 Net current-period other comprehensive (loss) income, net of tax (39,947) 9,947 — 506 (29,494) Ending balance, net of tax $ 76,131 $ (7,144) $ 149 $ (29,550) $ 39,586 Three Months Ended March 31, 2020 Pension Plans Unrealized Gains (Losses) on Securities Unrealized Gains (Losses) on Derivatives Net Prior Service (Cost) Credit Net Gain (Loss) Total Beginning balance, net of tax $ 38,038 $ (1,672) $ (145) $ (31,985) $ 4,236 Other comprehensive income (loss): Other comprehensive income (loss) before reclassifications 61,486 (19,600) — — 41,886 Reclassification adjustments included in net income (5,420) (101) (1) 728 (4,794) Income tax (expense) benefit (11,774) 4,137 — (152) (7,789) Net current-period other comprehensive income (loss), net of tax 44,292 (15,564) (1) 576 29,303 Ending balance, net of tax $ 82,330 $ (17,236) $ (146) $ (31,409) $ 33,539
Reclassifications out of accumulated other comprehensive income	The reclassification adjustments out of accumulated other comprehensive income (loss) included in net income are presented below (in thousands): Three Months Ended 2021 2020 Unrealized gains and losses on securities transferred: Amortization of unrealized gains and losses (1) $ (416) $ (121) Tax benefit 87 25 Net of tax (329) (96) Unrealized gains and losses on available for sale securities: Realized net gain on sale of securities (2) 2,003 5,541 Tax expense (420) (1,164) Net of tax 1,583 4,377 Derivatives: Realized net (loss) gain on interest rate swap derivatives (3) (1,568) 93 Tax benefit (expense) 329 (19) Net of tax (1,239) 74 Amortization of unrealized gains on terminated interest rate swap derivatives (3) — 8 Tax expense — (1) Net of tax — 7 Amortization of pension plan: Net actuarial loss (4) (641) (728) Prior service credit (4) — 1 Total before tax (641) (727) Tax benefit 135 152 Net of tax (506) (575) Total reclassifications for the period, net of tax $ (491) $ 3,787 (1) Included in interest income on the consolidated statements of income. (2) Listed as net gain on sale of securities AFS on the consolidated statements of income. (3) Included in interest expense for FHLB borrowings on the consolidated statements of income. (4) These AOCI components are included in the computation of net periodic pension cost (income) presented in “Note 8 – Employee Benefit Plans.”

Securities (Tables)

Securities (Tables)	3 Months Ended
	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Amortized cost and estimated fair value of investment and mortgage-backed securities	The amortized cost, gross unrealized gains and losses and estimated fair value of investment and mortgage-backed AFS and HTM securities as of March 31, 2021 and December 31, 2020 are reflected in the tables below (in thousands): March 31, 2021 Amortized Gross Unrealized Gross Unrealized Estimated AVAILABLE FOR SALE Cost Gains Losses Fair Value Investment securities: U.S. Treasury $ 42,818 $ 8 $ 349 $ 42,477 State and political subdivisions 1,528,516 71,813 8,684 1,591,645 Other stocks and bonds 91,439 1,560 216 92,783 MBS: (1) Residential 675,795 31,580 301 707,074 Commercial 109,545 3,802 402 112,945 Total $ 2,448,113 $ 108,763 $ 9,952 $ 2,546,924 HELD TO MATURITY Investment securities: State and political subdivisions $ 908 $ 9 $ — $ 917 MBS: (1) Residential 45,274 3,006 — 48,280 Commercial 51,977 3,003 — 54,980 Total $ 98,159 $ 6,018 $ — $ 104,177 December 31, 2020 Amortized Gross Unrealized Gross Unrealized Estimated AVAILABLE FOR SALE Cost Gains Losses Fair Value Investment securities: State and political subdivisions $ 1,475,030 $ 105,601 $ 37 $ 1,580,594 Other stocks and bonds 77,224 1,053 22 78,255 MBS: (1) Residential 771,409 38,674 73 810,010 Commercial 113,850 4,746 150 118,446 Total $ 2,437,513 $ 150,074 $ 282 $ 2,587,305 HELD TO MATURITY Investment securities: State and political subdivisions $ 907 $ 13 $ — $ 920 MBS: (1) Residential 47,948 4,187 — 52,135 Commercial 60,143 5,000 — 65,143 Total $ 108,998 $ 9,200 $ — $ 118,198 (1) All MBS issued and/or guaranteed by U.S. government agencies or U.S. GSEs.
Unrealized loss on securities	The following tables represent the fair value and unrealized losses on AFS investment and MBS for which an allowance for credit losses has not been recorded as of March 31, 2021 and December 31, 2020, segregated by major security type and length of time in a continuous loss position (in thousands): March 31, 2021 Less Than 12 Months More Than 12 Months Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss AVAILABLE FOR SALE Investment securities: U.S. Treasury $ 23,599 $ 349 $ — $ — $ 23,599 $ 349 State and political subdivisions 205,469 8,684 — — 205,469 8,684 Other stocks and bonds 28,845 216 — — 28,845 216 MBS: Residential 7,769 301 — — 7,769 301 Commercial 4,488 402 — — 4,488 402 Total $ 270,170 $ 9,952 $ — $ — $ 270,170 $ 9,952 December 31, 2020 Less Than 12 Months More Than 12 Months Total Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized AVAILABLE FOR SALE Investment securities: State and political subdivisions $ 17,305 $ 37 $ — $ — $ 17,305 $ 37 Other stocks and bonds 11,562 22 — — 11,562 22 MBS: Residential 6,287 73 — — 6,287 73 Commercial 4,744 150 — — 4,744 150 Total $ 39,898 $ 282 $ — $ — $ 39,898 $ 282
Interest income recognized on securities	The following table reflects interest income recognized on securities for the periods presented (in thousands): Three Months Ended 2021 2020 U.S. Treasury $ 37 $ — State and political subdivisions 10,406 6,625 Other stocks and bonds 845 93 MBS 6,088 11,534 Total interest income on securities $ 17,376 $ 18,252
Amortized cost, carrying value and fair value of securities presented by contractual maturity	The amortized cost and estimated fair value of AFS and HTM securities at March 31, 2021, are presented below by contractual maturity (in thousands): March 31, 2021 Amortized Cost Fair Value AVAILABLE FOR SALE Investment securities: Due in one year or less $ 1,036 $ 1,061 Due after one year through five years 32,542 33,937 Due after five years through ten years 93,914 96,177 Due after ten years 1,535,281 1,595,730 1,662,773 1,726,905 MBS: 785,340 820,019 Total $ 2,448,113 $ 2,546,924 March 31, 2021 Amortized Cost Fair Value HELD TO MATURITY Investment securities: Due in one year or less $ 120 $ 121 Due after one year through five years 509 514 Due after five years through ten years 279 282 Due after ten years — — 908 917 MBS: 97,251 103,260 Total $ 98,159 $ 104,177
Unrealized and realized gains (losses) recognized in net income on equity investments	The following is a summary of unrealized and realized gains and losses on equity investments recognized in other noninterest income in the consolidated statements of income during the periods presented (in thousands): Three Months Ended 2021 2020 Net (losses) gains recognized during the period on equity investments $ (107) $ 53 Less: Net gains recognized during the period on equity investments sold during the period — — Unrealized (losses) gains recognized during the reporting period on equity investments held at the reporting date $ (107) $ 53

Loans and Allowance for Loan _2

Loans and Allowance for Loan Losses (Tables)	3 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Loans by Portfolio Segment	Loans in the accompanying consolidated balance sheets are classified as follows (in thousands): March 31, 2021 December 31, 2020 Real estate loans: Construction $ 605,677 $ 581,941 1-4 family residential 700,430 719,952 Commercial 1,348,551 1,295,746 Commercial loans 564,745 557,122 Municipal loans 406,377 409,028 Loans to individuals 90,818 93,990 Total loans 3,716,598 3,657,779 Less: Allowance for loan losses 41,454 49,006 Net loans $ 3,675,144 $ 3,608,773
Summary of loans by credit quality indicators and origination year	The following tables set forth the amortized cost basis by class of financing receivable and credit quality indicator for the periods presented (in thousands): March 31, 2021 Term Loans Amortized Cost Basis by Origination Year Revolving Loans Amortized Cost Basis Total 2021 2020 2019 2018 2017 Prior Construction real estate: Pass $ 26,255 $ 160,527 $ 182,708 $ 75,258 $ 33,261 $ 8,877 $ 118,479 $ 605,365 Pass watch — — — — — 22 — 22 Special mention — — — — — — — — Substandard — — — — — 54 — 54 Doubtful — — — 59 — 177 — 236 Total construction real estate $ 26,255 $ 160,527 $ 182,708 $ 75,317 $ 33,261 $ 9,130 $ 118,479 $ 605,677 1-4 family residential real estate: Pass $ 39,457 $ 151,235 $ 104,065 $ 63,864 $ 46,692 $ 283,115 $ 2,506 $ 690,934 Pass watch — — — — — 823 — 823 Special mention — — — — — 65 — 65 Substandard 10 1,684 — — 943 5,289 94 8,020 Doubtful — 14 — 135 34 405 — 588 Total 1-4 family residential real estate $ 39,467 $ 152,933 $ 104,065 $ 63,999 $ 47,669 $ 289,697 $ 2,600 $ 700,430 Commercial real estate: Pass $ 138,805 $ 236,874 $ 285,638 $ 110,462 $ 181,077 $ 247,524 $ 6,857 $ 1,207,237 Pass watch — — — 23,272 37,938 5,472 — 66,682 Special mention 24,142 577 8,883 7,002 138 12,245 — 52,987 Substandard 2,105 4,631 — 1,956 63 12,756 — 21,511 Doubtful — — — — — 134 — 134 Total commercial real estate $ 165,052 $ 242,082 $ 294,521 $ 142,692 $ 219,216 $ 278,131 $ 6,857 $ 1,348,551 Commercial loans: Pass $ 108,205 $ 221,819 $ 41,605 $ 17,819 $ 6,368 $ 8,280 $ 146,516 $ 550,612 Pass watch 43 2,313 1,199 2,004 1,487 — 378 7,424 Special mention 280 — 718 416 36 385 320 2,155 Substandard 185 454 989 481 2 — 1,486 3,597 Doubtful — 382 95 449 31 — — 957 Total commercial loans $ 108,713 $ 224,968 $ 44,606 $ 21,169 $ 7,924 $ 8,665 $ 148,700 $ 564,745 Municipal loans: Pass $ 14,748 $ 69,822 $ 66,741 $ 32,166 $ 59,756 $ 163,144 $ — $ 406,377 Pass watch — — — — — — — — Special mention — — — — — — — — Substandard — — — — — — — — Doubtful — — — — — — — — Total municipal loans $ 14,748 $ 69,822 $ 66,741 $ 32,166 $ 59,756 $ 163,144 $ — $ 406,377 Loans to individuals: Pass $ 12,798 $ 39,592 $ 20,715 $ 8,079 $ 3,672 $ 2,079 $ 3,521 $ 90,456 Pass watch — — — — — — — — Special mention — — — 47 — — 4 51 Substandard — 19 34 22 27 10 — 112 Doubtful — 67 — 5 44 83 — 199 Total loans to individuals $ 12,798 $ 39,678 $ 20,749 $ 8,153 $ 3,743 $ 2,172 $ 3,525 $ 90,818 Total loans $ 367,033 $ 890,010 $ 713,390 $ 343,496 $ 371,569 $ 750,939 $ 280,161 $ 3,716,598 December 31, 2020 Term Loans Amortized Cost Basis by Origination Year Revolving Loans Amortized Cost Basis Total 2020 2019 2018 2017 2016 Prior Construction real estate: Pass $ 155,693 $ 180,536 $ 76,090 $ 55,636 $ 3,191 $ 8,297 $ 101,793 $ 581,236 Pass watch — — — — 23 — — 23 Special mention — — — — — — — — Substandard — 382 62 — — 58 — 502 Doubtful — — — — — 180 — 180 Total construction real estate $ 155,693 $ 180,918 $ 76,152 $ 55,636 $ 3,214 $ 8,535 $ 101,793 $ 581,941 1-4 family residential real estate: Pass $ 154,003 $ 114,063 $ 70,621 $ 55,557 $ 57,680 $ 255,003 $ 2,833 $ 709,760 Pass watch — — — — 267 564 — 831 Special mention — — — — — 10 — 10 Substandard 1,473 — 135 427 1,588 5,134 96 8,853 Doubtful — — — 36 103 359 — 498 Total 1-4 family residential real estate $ 155,476 $ 114,063 $ 70,756 $ 56,020 $ 59,638 $ 261,070 $ 2,929 $ 719,952 Commercial real estate: Pass $ 270,087 $ 307,161 $ 143,177 $ 162,180 $ 98,828 $ 179,919 $ 6,957 $ 1,168,309 Pass watch — — 3,153 40,125 1,696 2,582 — 47,556 Special mention 4,555 33,020 7,041 140 4,531 7,850 — 57,137 Substandard 7,542 — 2,097 65 704 12,282 — 22,690 Doubtful — — — — — 54 — 54 Total commercial real estate $ 282,184 $ 340,181 $ 155,468 $ 202,510 $ 105,759 $ 202,687 $ 6,957 $ 1,295,746 Commercial loans: Pass $ 313,688 $ 47,446 $ 20,386 $ 7,505 $ 3,392 $ 6,142 $ 140,018 $ 538,577 Pass watch 2,599 1,318 2,410 1,981 — — 370 8,678 Special mention 304 809 433 39 286 265 455 2,591 Substandard 405 1,081 473 7 — — 4,417 6,383 Doubtful 310 53 475 54 1 — — 893 Total commercial loans $ 317,306 $ 50,707 $ 24,177 $ 9,586 $ 3,679 $ 6,407 $ 145,260 $ 557,122 Municipal loans: Pass $ 72,542 $ 68,132 $ 33,735 $ 61,170 $ 25,387 $ 148,062 $ — $ 409,028 Pass watch — — — — — — — — Special mention — — — — — — — — Substandard — — — — — — — — Doubtful — — — — — — — — Total municipal loans $ 72,542 $ 68,132 $ 33,735 $ 61,170 $ 25,387 $ 148,062 $ — $ 409,028 Loans to individuals: Pass $ 46,722 $ 25,302 $ 10,132 $ 4,716 $ 1,867 $ 917 $ 3,900 $ 93,556 Pass watch — — — — — — — — Special mention — — 51 — — — 4 55 Substandard 6 35 28 30 9 11 1 120 Doubtful 73 20 6 55 81 24 — 259 Total loans to individuals $ 46,801 $ 25,357 $ 10,217 $ 4,801 $ 1,957 $ 952 $ 3,905 $ 93,990 Total loans $ 1,030,002 $ 779,358 $ 370,505 $ 389,723 $ 199,634 $ 627,713 $ 260,844 $ 3,657,779
Aging of past due loans by class of loan	The following tables present the aging of the amortized cost basis in past due loans by class of loans (in thousands): March 31, 2021 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days Past Due Total Past Due Current Total Real estate loans: Construction $ 1,130 $ — $ — $ 1,130 $ 604,547 $ 605,677 1-4 family residential 5,321 614 486 6,421 694,009 700,430 Commercial 4,676 — — 4,676 1,343,875 1,348,551 Commercial loans 1,507 245 641 2,393 562,352 564,745 Municipal loans — — — — 406,377 406,377 Loans to individuals 418 30 3 451 90,367 90,818 Total $ 13,052 $ 889 $ 1,130 $ 15,071 $ 3,701,527 $ 3,716,598 December 31, 2020 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days Total Past Due Current Total Real estate loans: Construction $ 95 $ 14 $ 444 $ 553 $ 581,388 $ 581,941 1-4 family residential 7,872 2,469 2,830 13,171 706,781 719,952 Commercial 467 315 86 868 1,294,878 1,295,746 Commercial loans 1,423 4,516 323 6,262 550,860 557,122 Municipal loans 64 — — 64 408,964 409,028 Loans to individuals 519 123 27 669 93,321 93,990 Total $ 10,440 $ 7,437 $ 3,710 $ 21,587 $ 3,636,192 $ 3,657,779
Nonperforming assets by asset class	The following table sets forth the amortized cost basis of nonperforming assets for the periods presented (in thousands): March 31, 2021 December 31, 2020 Nonaccrual loans: Real estate loans: Construction $ 248 $ 640 1-4 family residential 1,929 3,922 Commercial 1,229 1,269 Commercial loans 1,682 1,592 Loans to individuals 226 291 Total nonaccrual loans (1) 5,314 7,714 Accruing loans past due more than 90 days — — TDR loans 9,641 9,646 OREO 412 106 Repossessed assets — 14 Total nonperforming assets $ 15,367 $ 17,480 (1) Includes $889,000 and $976,000 of restructured loans as of March 31, 2021 and December 31, 2020, respectively.
Troubled debt restructurings	The following tables set forth the recorded balance of loans considered to be TDRs that were restructured and the type of concession by class of loans during the periods presented (dollars in thousands): Three Months Ended March 31, 2021 Extend Amortization Period Interest Rate Reductions Combination Total Modifications Number of Loans Real estate loans: 1-4 family residential $ — $ — $ 130 $ 130 2 Commercial loans — — 18 18 1 Total $ — $ — $ 148 $ 148 3 Three Months Ended March 31, 2020 Extend Amortization Period Interest Rate Reductions Combination Total Modifications Number of Loans Real estate loans: Commercial $ — $ — $ 59 $ 59 1 Commercial loans — — 3 3 1 Total $ — $ — $ 62 $ 62 2
Allowance for loan losses activity by portfolio segment	The following tables detail activity in the allowance for loan losses by portfolio segment for the periods presented (in thousands): Three Months Ended March 31, 2021 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Balance at beginning of period $ 6,490 $ 2,270 $ 35,709 $ 4,107 $ 46 $ 384 $ 49,006 Loans charged-off — (73) — (319) — (403) (795) Recoveries of loans charged-off 1 55 — 282 — 284 622 Net loans (charged-off) recovered 1 (18) — (37) — (119) (173) Provision for (reversal of) loan losses 1,710 256 (8,473) (962) — 90 (7,379) Balance at end of period $ 8,201 $ 2,508 $ 27,236 $ 3,108 $ 46 $ 355 $ 41,454 Three Months Ended March 31, 2020 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Balance at beginning of period $ 3,539 $ 3,833 $ 9,572 $ 6,351 $ 570 $ 932 $ 24,797 Impact of CECL adoption - cumulative effect adjustment 2,968 (1,447) 7,730 (3,532) (522) (125) 5,072 Impact of CECL adoption - purchased loans with credit deterioration (15) (6) 333 (22) — (59) 231 Loans charged-off (33) (54) (21) (296) — (591) (995) Recoveries of loans charged-off 11 4 69 74 — 293 451 Net loans (charged-off) recovered (22) (50) 48 (222) — (298) (544) Provision for (reversal of) loan losses (1) 3,184 310 18,437 1,944 (1) 208 24,082 Balance at end of period $ 9,654 $ 2,640 $ 36,120 $ 4,519 $ 47 $ 658 $ 53,638 (1) The increase in the provision for credit losses during 2020 was primarily due to the economic impact of COVID-19 on macroeconomic factors used in the CECL model.

Borrowing Arrangements (Tables)

Borrowing Arrangements (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of Debt	Information related to borrowings is provided in the table below (dollars in thousands): March 31, 2021 December 31, 2020 Other borrowings: Balance at end of period $ 22,315 $ 23,172 Average amount outstanding during the period (1) 23,522 91,940 Maximum amount outstanding during the period (2) 24,549 219,259 Weighted average interest rate during the period (3) 0.2 % 0.4 % Interest rate at end of period (4) 0.2 % 0.1 % FHLB borrowings: Balance at end of period $ 665,530 $ 832,527 Average amount outstanding during the period (1) 727,513 1,032,269 Maximum amount outstanding during the period (2) 723,584 1,274,370 Weighted average interest rate during the period (3) 1.1 % 1.1 % Interest rate at end of period (4) 1.1 % 1.0 % (1) The average amount outstanding during the period was computed by dividing the total daily outstanding principal balances by the number of days in the period. (2) The maximum amount outstanding at any month-end during the period. (3) The weighted average interest rate during the period was computed by dividing the actual interest expense (annualized for interim periods) by the average amount outstanding during the period. The weighted average interest rate on the FHLB borrowings includes the effect of interest rate swaps. (4) Stated rate.
Schedule of Maturities of Borrowings	Maturities of the obligations associated with our borrowing arrangements based on scheduled repayments at March 31, 2021 are as follows (in thousands): Payments Due by Period Less than 1-2 Years 2-3 Years 3-4 Years 4-5 Years Thereafter Total Other borrowings $ 22,315 $ — $ — $ — $ — $ — $ 22,315 FHLB borrowings 661,659 687 717 748 775 944 665,530 Total obligations $ 683,974 $ 687 $ 717 $ 748 $ 775 $ 944 $ 687,845

Long-term Debt (Tables)

Long-term Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Information related to our long-term debt is summarized as follows for the periods presented (in thousands): March 31, 2021 December 31, 2020 Subordinated notes: (1) 3.875% Subordinated notes, net of unamortized debt issuance costs (2) $ 98,469 $ 98,497 5.50% Subordinated notes, net of unamortized debt issuance costs (3) 98,799 98,754 Total Subordinated notes 197,268 197,251 Trust preferred subordinated debentures: (4) Southside Statutory Trust III, net of unamortized debt issuance costs (5) 20,564 20,563 Southside Statutory Trust IV 23,196 23,196 Southside Statutory Trust V 12,887 12,887 Magnolia Trust Company I 3,609 3,609 Total Trust preferred subordinated debentures 60,256 60,255 Total Long-term debt $ 257,524 $ 257,506 (1) This debt consists of subordinated notes with a remaining maturity greater than one year that qualify under the risk-based capital guidelines as Tier 2 capital, subject to certain limitations. (2) The unamortized discount and debt issuance costs reflected in the carrying amount of the subordinated notes totaled approximately $1.5 million at March 31, 2021 and December 31, 2020. (3) The unamortized discount and debt issuance costs reflected in the carrying amount of the subordinated notes totaled approximately $1.2 million at March 31, 2021 and December 31, 2020. (4) This debt consists of trust preferred securities that qualify under the risk-based capital guidelines as Tier 1 capital, subject to certain limitations.
Schedule of Subordinated Borrowing	As of March 31, 2021, the details of the subordinated notes and the trust preferred subordinated debentures are summarized below (dollars in thousands): Date Issued Amount Issued Fixed or Floating Rate Interest Rate Maturity Date 3.875% Subordinated Notes November 6, 2020 $ 100,000 Fixed-to-Floating 3.875% November 15, 2030 5.50% Subordinated Notes September 19, 2016 $ 100,000 Fixed-to-Floating 5.50% September 30, 2026 Southside Statutory Trust III September 4, 2003 $ 20,619 Floating 3 month LIBOR + 2.94% September 4, 2033 Southside Statutory Trust IV August 8, 2007 $ 23,196 Floating 3 month LIBOR + 1.30% October 30, 2037 Southside Statutory Trust V August 10, 2007 $ 12,887 Floating 3 month LIBOR + 2.25% September 15, 2037 Magnolia Trust Company I (1) October 10, 2007 $ 3,609 Floating 3 month LIBOR + 1.80% November 23, 2035

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2021
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
The components of net periodic benefit cost	The components of net periodic benefit cost (income) related to our employee benefit plans are as follows (in thousands): Three Months Ended March 31, Defined Benefit Defined Benefit Pension Plan Acquired Restoration 2021 2020 2021 2020 2021 2020 Service cost $ — $ 423 $ — $ — $ — $ 85 Interest cost 628 837 24 41 121 160 Expected return on assets (1,437) (1,668) (58) (84) — — Net loss amortization 520 533 3 2 118 193 Prior service (credit) cost amortization — (3) — — — 2 Net periodic benefit (income) cost $ (289) $ 122 $ (31) $ (41) $ 239 $ 440

Derivative Financial Instrume_2

Derivative Financial Instruments and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following tables present the notional and estimated fair value amount of derivative positions outstanding (in thousands): March 31, 2021 December 31, 2020 Estimated Fair Value Estimated Fair Value Notional (1) Asset Derivative Liability Derivative Notional (1) Asset Derivative Liability Derivative Derivatives designated as hedging instruments Interest rate contracts: Swaps-Cash Flow Hedge-Financial institution counterparties $ 625,000 $ 2,145 $ 11,189 $ 670,000 $ — $ 21,635 Derivatives designated as non-hedging instruments Interest rate contracts: Swaps-Financial institution counterparties 217,655 910 10,980 152,280 — 18,537 Swaps-Customer counterparties 217,655 10,980 910 152,280 18,537 — Gross derivatives 14,035 23,079 18,537 40,172 Offsetting derivative assets/liabilities (3,055) (3,055) — — Cash collateral received/posted — (19,114) — (39,270) Net derivatives included in the consolidated balance sheets (2) $ 10,980 $ 910 $ 18,537 $ 902 (1) Notional amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the consolidated balance sheets. (2) Net derivative assets are included in other assets and net derivative liabilities are included in other liabilities on the consolidated balance sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and our credit risk. We had $1.3 million credit exposure related to interest rate swaps with financial institutions and $11.0 million related to interest rate swaps with customers at March 31, 2021. We had no credit exposure related to interest rate swaps with financial institutions and $18.5 million related to interest rate swaps with customers at
Weighted Average Maturity And Interest Rates On Risk Management Interest Rate Swaps	The summarized expected weighted average remaining maturity of the notional amount of interest rate swaps and the weighted average interest rates associated with the amounts expected to be received or paid on interest rate swap agreements are presented below (dollars in thousands). Variable rates received on fixed pay swaps are based on one-month or three-month LIBOR rates in effect at March 31, 2021 and December 31, 2020: March 31, 2021 December 31, 2020 Weighted Average Weighted Average Notional Amount Remaining Maturity Receive Rate Pay Rate Notional Amount Remaining Maturity Receive Rate Pay Swaps-Cash Flow hedge Financial institution counterparties $ 625,000 3.8 0.14 % 1.11 % $ 670,000 3.8 0.17 % 1.12 % Swaps-Non-hedging Financial institution counterparties 217,655 11.0 0.52 % 2.43 % 152,280 9.8 0.50 % 2.57 % Customer counterparties 217,655 11.0 2.43 % 0.52 % 152,280 9.8 2.57 % 0.50 %

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Summary of fair value measurement on recurring and nonrecurring basis segregated by level of valuation inputs within fair value hierarchy utilized to measure fair value	The following tables summarize assets measured at fair value on a recurring and nonrecurring basis segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands): Fair Value Measurements at the End of the Reporting Period Using March 31, 2021 Carrying Amount Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Recurring fair value measurements Investment securities: U.S. Treasury $ 42,477 $ 42,477 $ — $ — State and political subdivisions 1,591,645 — 1,591,645 — Other stocks and bonds 92,783 — 92,783 — MBS: (1) Residential 707,074 — 707,074 — Commercial 112,945 — 112,945 — Equity investments: Equity investments 5,988 5,988 — — Derivative assets: Interest rate swaps 14,035 — 14,035 — Total asset recurring fair value measurements $ 2,566,947 $ 48,465 $ 2,518,482 $ — Derivative liabilities: Interest rate swaps $ 23,079 $ — $ 23,079 $ — Total liability recurring fair value measurements $ 23,079 $ — $ 23,079 $ — Nonrecurring fair value measurements Foreclosed assets $ 412 $ — $ — $ 412 Collateral-dependent loans (2) 10,223 — — 10,223 Total asset nonrecurring fair value measurements $ 10,635 $ — $ — $ 10,635 Fair Value Measurements at the End of the Reporting Period Using December 31, 2020 Carrying Amount Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Recurring fair value measurements Investment securities: State and political subdivisions $ 1,580,594 $ — $ 1,580,594 $ — Other stocks and bonds 78,255 — 78,255 — MBS: (1) Residential 810,010 — 810,010 — Commercial 118,446 — 118,446 — Equity investments: Equity investments 6,094 6,094 — — Derivative assets: Interest rate swaps 18,537 — 18,537 — Total asset recurring fair value measurements $ 2,611,936 $ 6,094 $ 2,605,842 $ — Derivative liabilities: Interest rate swaps $ 40,172 $ — $ 40,172 $ — Total liability recurring fair value measurements $ 40,172 $ — $ 40,172 $ — Nonrecurring fair value measurements Foreclosed assets $ 120 $ — $ — $ 120 Collateral-dependent loans (2) 10,653 — — 10,653 Total asset nonrecurring fair value measurements $ 10,773 $ — $ — $ 10,773 (1) All MBS are issued and/or guaranteed by U.S. government agencies or U.S. GSEs. (2) Consists of individually evaluated loans. Loans for which the fair value of the collateral and commercial real estate fair value of the properties is less than cost basis are presented net of allowance. Losses on these loans represent charge-offs which are netted against the allowance for loan losses.
Financial assets, financial liabilities, and unrecognized financial instruments at carrying amount and fair value	The following tables present our financial assets and financial liabilities measured on a nonrecurring basis at both their respective carrying amounts and estimated fair value (in thousands): Estimated Fair Value March 31, 2021 Carrying Total Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 107,623 $ 107,623 $ 107,623 $ — $ — Investment securities: HTM, at carrying value 908 917 — 917 — MBS: HTM, at carrying value 97,251 103,260 — 103,260 — FHLB stock, at cost 18,754 18,754 — 18,754 — Equity investments 5,816 5,816 — 5,816 — Loans, net of allowance for loan losses 3,675,144 3,833,854 — — 3,833,854 Loans held for sale 2,615 2,615 — 2,615 — Financial liabilities: Deposits $ 5,092,643 $ 5,095,397 $ — $ 5,095,397 $ — Other borrowings 22,315 22,315 — 22,315 — FHLB borrowings 665,530 675,135 — 675,135 — Subordinated notes, net of unamortized debt issuance costs 197,268 198,103 — 198,103 — Trust preferred subordinated debentures, net of unamortized debt issuance costs 60,256 47,183 — 47,183 — Estimated Fair Value December 31, 2020 Carrying Total Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 108,408 $ 108,408 $ 108,408 $ — $ — Investment securities: HTM, at carrying value 907 920 — 920 — Mortgage-backed securities: HTM, at carrying value 108,091 117,278 — 117,278 — Federal Home Loan Bank stock, at cost 25,259 25,259 — 25,259 — Equity investments 5,811 5,811 — 5,811 — Loans, net of allowance for loan losses 3,608,773 3,784,291 — — 3,784,291 Loans held for sale 3,695 3,695 — 3,695 — Financial liabilities: Deposits $ 4,932,322 $ 4,936,188 $ — $ 4,936,188 $ — Other borrowings 23,172 23,172 — 23,172 — FHLB borrowings 832,527 854,865 — 854,865 — Subordinated notes, net of unamortized debt issuance costs 197,251 198,391 — 198,391 — Trust preferred subordinated debentures, net of unamortized debt issuance costs 60,255 51,993 — 51,993 —

Income Taxes Income Taxes (Tabl

Income Taxes Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	The income tax expense included in the accompanying consolidated statements of income consists of the following (in thousands): Three Months Ended 2021 2020 Current income tax expense $ 2,589 $ 5,554 Deferred income tax expense (benefit) 2,161 (5,075) Income tax expense $ 4,750 $ 479

Off-Balance-Sheet Arrangement_2

Off-Balance-Sheet Arrangements, Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Off-balance-sheet, Allowance for off-balance-sheet credit exposures	Allowance for off-balance-sheet credit exposures were as follows (in thousands): Three Months Ended 2021 2020 Balance at beginning of period $ 6,386 $ 1,455 Impact of CECL adoption — 4,840 Provision for (reversal of) off-balance-sheet credit exposures (2,770) 1,165 Balance at end of period $ 3,616 $ 7,460
Schedule of unused commitments	Financial instruments with off-balance-sheet risk were as follows (in thousands): March 31, 2021 December 31, 2020 Commitments to extend credit $ 811,574 $ 793,138 Standby letters of credit 10,825 13,658 Total $ 822,399 $ 806,796

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Basic and Diluted Earnings:
Net income	$ 34,091	$ 3,953
Basic weighted-average shares outstanding (in shares)	32,829	33,691
Add: Stock awards (in shares)	108	114
Diluted weighted-average shares outstanding (in shares)	32,937	33,805
Basic earnings per share:
Earnings per common share - basic (in dollars per share)	$ 1.04	$ 0.12
Diluted earnings per share:
Earnings per common share - diluted (in dollars per share)	$ 1.04	$ 0.12
Antidilutive securities excluded from calculating earnings
Number of antidilutive options (in shares)	679	775

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Accumulated Other Comprehensive Income, Changes In (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax		$ 875,297	$ 804,580
Income tax benefit (expense)		7,840	(7,789)
Ending balance, net of tax		858,597	795,800
Unrealized Gains (Losses) on Securities
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax		116,078	38,038
Other comprehensive (loss) income before reclassifications		(48,979)	61,486
Reclassification adjustments included in net income		(1,587)	(5,420)
Income tax benefit (expense)		10,619	(11,774)
Net current-period other comprehensive (loss) income, net of tax		(39,947)	44,292
Ending balance, net of tax		76,131	82,330
Unrealized Gains (Losses) on Derivatives
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax		(17,091)	(1,672)
Other comprehensive (loss) income before reclassifications		11,023	(19,600)
Reclassification adjustments included in net income		1,568	(101)
Income tax benefit (expense)		(2,644)	4,137
Net current-period other comprehensive (loss) income, net of tax		9,947	(15,564)
Ending balance, net of tax		(7,144)	(17,236)
Net Prior Service (Cost) Credit
AOCI Attributable to Parent, Net of Tax
Reclassification adjustments included in net income	[1]	0	(1)
Net Gain (Loss)
AOCI Attributable to Parent, Net of Tax
Reclassification adjustments included in net income	[1]	641	728
Total
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax		69,080	4,236
Other comprehensive (loss) income before reclassifications		(37,956)	41,886
Reclassification adjustments included in net income		622	(4,794)
Income tax benefit (expense)		7,840	(7,789)
Net current-period other comprehensive (loss) income, net of tax		(29,494)	29,303
Ending balance, net of tax		39,586	33,539
Pension Plans | Net Prior Service (Cost) Credit
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax		149	(145)
Other comprehensive (loss) income before reclassifications		0	0
Reclassification adjustments included in net income		0	(1)
Income tax benefit (expense)		0	0
Net current-period other comprehensive (loss) income, net of tax		0	(1)
Ending balance, net of tax		149	(146)
Pension Plans | Net Gain (Loss)
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax		(30,056)	(31,985)
Other comprehensive (loss) income before reclassifications		0	0
Reclassification adjustments included in net income		641	728
Income tax benefit (expense)		(135)	(152)
Net current-period other comprehensive (loss) income, net of tax		506	576
Ending balance, net of tax		$ (29,550)	$ (31,409)
[1]	These AOCI components are included in the computation of net periodic pension cost (income) presented in “Note 8 – Employee Benefit Plans.”

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Reclassifications out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of unrealized gains and losses		$ 416	$ 121
Tax benefit (expense)		(4,750)	(479)
Realized net gain on sale of securities		2,003	5,541
Total reclassifications for the period, net of tax		(491)	3,787
Unrealized gains (losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassified from accumulated other comprehensive income		1,587	5,420
Realized net gain (loss) on interest rate swap derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassified from accumulated other comprehensive income		(1,568)	101
Net actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassified from accumulated other comprehensive income	[1]	(641)	(728)
Prior service credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassified from accumulated other comprehensive income	[1]	0	1
Amortization of pension plan
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassified from accumulated other comprehensive income		(641)	(727)
Tax benefit		135	152
Total reclassifications for the period, net of tax		(506)	(575)
Unrealized gains and losses on securities transferred | Reclassification out of accumulated other comprehensive income | Unrealized gains (losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of unrealized gains and losses	[2]	(416)	(121)
Tax benefit (expense)		87	25
Net of tax		(329)	(96)
Unrealized gains and losses on available for sale securities | Reclassification out of accumulated other comprehensive income | Unrealized gains (losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax benefit (expense)		(420)	(1,164)
Net of tax		1,583	4,377
Realized net gain on sale of securities	[3]	2,003	5,541
Interest rate swap derivatives | Reclassification out of accumulated other comprehensive income | Realized net gain (loss) on interest rate swap derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax benefit (expense)		329	(19)
Net of tax		(1,239)	74
Realized net (loss) gain on interest rate swap derivatives	[4]	(1,568)	93
Interest rate swap derivatives | Reclassification out of accumulated other comprehensive income | Amortization of unrealized gains on terminated interest rate swap derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax benefit (expense)		0	(1)
Net of tax		0	7
Realized net (loss) gain on interest rate swap derivatives	[4]	$ 0	$ 8
[1]	These AOCI components are included in the computation of net periodic pension cost (income) presented in “Note 8 – Employee Benefit Plans.”
[2]	Included in interest income on the consolidated statements of income.
[3]	Listed as net gain on sale of securities AFS on the consolidated statements of income.
[4]	Included in interest expense for FHLB borrowings on the consolidated statements of income.

Securities - Schedule of Debt S

Securities - Schedule of Debt Securities Components (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Available-for-sale [Abstract]
Amortized Cost		$ 2,448,113	$ 2,437,513
Gross unrealized gains		108,763	150,074
Gross unrealized losses		9,952	282
Securities available for sale, at estimated fair value		2,546,924	2,587,305
HELD TO MATURITY
Amortized cost		98,159	108,998
Gross unrealized gains		6,018	9,200
Gross unrealized losses		0	0
Estimated Fair Value		104,177	118,198
US Treasury Securities
Available-for-sale [Abstract]
Amortized Cost		42,818
Gross unrealized gains		8
Gross unrealized losses		349
Securities available for sale, at estimated fair value		42,477
State and political subdivisions
Available-for-sale [Abstract]
Amortized Cost		1,528,516	1,475,030
Gross unrealized gains		71,813	105,601
Gross unrealized losses		8,684	37
Securities available for sale, at estimated fair value		1,591,645	1,580,594
HELD TO MATURITY
Amortized cost		908	907
Gross unrealized gains		9	13
Gross unrealized losses		0	0
Estimated Fair Value		917	920
Other stocks and bonds
Available-for-sale [Abstract]
Amortized Cost		91,439	77,224
Gross unrealized gains		1,560	1,053
Gross unrealized losses		216	22
Securities available for sale, at estimated fair value		92,783	78,255
Residential
Available-for-sale [Abstract]
Amortized Cost	[1]	675,795	771,409
Gross unrealized gains	[1]	31,580	38,674
Gross unrealized losses	[1]	301	73
Securities available for sale, at estimated fair value	[1]	707,074	810,010
HELD TO MATURITY
Amortized cost	[1]	45,274	47,948
Gross unrealized gains	[1]	3,006	4,187
Gross unrealized losses	[1]	0	0
Estimated Fair Value	[1]	48,280	52,135
Commercial
Available-for-sale [Abstract]
Amortized Cost	[1]	109,545	113,850
Gross unrealized gains	[1]	3,802	4,746
Gross unrealized losses	[1]	402	150
Securities available for sale, at estimated fair value	[1]	112,945	118,446
HELD TO MATURITY
Amortized cost	[1]	51,977	60,143
Gross unrealized gains	[1]	3,003	5,000
Gross unrealized losses	[1]	0	0
Estimated Fair Value	[1]	$ 54,980	$ 65,143
[1]	All MBS issued and/or guaranteed by U.S. government agencies or U.S. GSEs.

Securities - Unrealized Loss on

Securities - Unrealized Loss on Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Available-for-sale, Unrealized Loss Position [Abstract]
Less than 12 Months, fair value	$ 270,170	$ 39,898
More than 12 Months, fair value	0	0
Total fair value	270,170	39,898
Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 Months, unrealized loss	9,952	282
More than 12 Months, unrealized Loss	0	0
Total unrealized loss	9,952	282
US Treasury Securities
Available-for-sale, Unrealized Loss Position [Abstract]
Less than 12 Months, fair value	23,599
More than 12 Months, fair value	0
Total fair value	23,599
Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 Months, unrealized loss	349
More than 12 Months, unrealized Loss	0
Total unrealized loss	349
State and political subdivisions
Available-for-sale, Unrealized Loss Position [Abstract]
Less than 12 Months, fair value	205,469	17,305
More than 12 Months, fair value	0	0
Total fair value	205,469	17,305
Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 Months, unrealized loss	8,684	37
More than 12 Months, unrealized Loss	0	0
Total unrealized loss	8,684	37
Other stocks and bonds
Available-for-sale, Unrealized Loss Position [Abstract]
Less than 12 Months, fair value	28,845	11,562
More than 12 Months, fair value	0	0
Total fair value	28,845	11,562
Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 Months, unrealized loss	216	22
More than 12 Months, unrealized Loss	0	0
Total unrealized loss	216	22
Residential
Available-for-sale, Unrealized Loss Position [Abstract]
Less than 12 Months, fair value	7,769	6,287
More than 12 Months, fair value	0	0
Total fair value	7,769	6,287
Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 Months, unrealized loss	301	73
More than 12 Months, unrealized Loss	0	0
Total unrealized loss	301	73
Commercial
Available-for-sale, Unrealized Loss Position [Abstract]
Less than 12 Months, fair value	4,488	4,744
More than 12 Months, fair value	0	0
Total fair value	4,488	4,744
Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 Months, unrealized loss	402	150
More than 12 Months, unrealized Loss	0	0
Total unrealized loss	$ 402	$ 150

Securities - Interest Income on

Securities - Interest Income on Securities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Investments, Debt Securities [Abstract]
US Treasury	$ 37	$ 0
State and political subdivisions	10,406	6,625
Other stocks and bonds	845	93
Mortgage-backed securities	6,088	11,534
Total interest income on securities	$ 17,376	$ 18,252

Securities - Amortized Cost and

Securities - Amortized Cost and Estimated Fair Value of Investments in Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Available for sale, Amortized Cost
Due in one year or less	$ 1,036
Due after one year through five years	32,542
Due after five years through ten years	93,914
Due after ten years	1,535,281
Total available-for-sale investment securities	1,662,773
MBS:	785,340
Amortized Cost	2,448,113	$ 2,437,513
Available for sale, Fair Value
Due in one year or less	1,061
Due after one year through five years	33,937
Due after five years through ten years	96,177
Due after ten years	1,595,730
Total available-for-sale investment securities	1,726,905
MBS:	820,019
Total	2,546,924	2,587,305
Held to maturity, Amortized Cost
Due in one year or less	120
Due after one year through five years	509
Due after five years through ten years	279
Due after ten years	0
Total held-to-maturity investment securities	908
Mortgage-backed securities	97,251
Amortized cost	98,159	108,998
Held to maturity, Fair Value
Due in one year or less	121
Due after one year through five years	514
Due after five years through ten years	282
Due after ten years	0
Total held-to-maturity investment securities	917
Mortgage-backed securities	103,260
Total	$ 104,177	$ 118,198

Securities - Unrealized and Rea

Securities - Unrealized and Realized Gain (Loss) Recognized in Net Income on Equity Investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Investments, All Other Investments [Abstract]
Net (losses) gains recognized during the period on equity investments	$ (107)	$ 53
Less: Net gains recognized during the period on equity investments sold during the period	0	0
Unrealized (losses) gains recognized during the reporting period on equity investments held at the reporting date	$ (107)	$ 53

Securities - Narrative (Details

Securities - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	$ 0	$ 0
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		$ 0
Debt Securities, Held-to-maturity, Credit Loss Expense (Reversal)	0	0
Transferred Securities, Unrealized Loss, Before Tax	2,400,000		2,900,000
Securities transferred, Unrealized Loss, Net of Tax	1,900,000		2,300,000
Fair value of securities transferred from AFS to HTM	0		0
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Net gain on sale of securities AFS	2,003,000	5,541,000
Gross realized gains on AFS securities	2,100,000	5,600,000
Gross realized losses on AFS securities	52,000	10,000
Carrying value of investment securities pledged as collateral	1,470,000,000		1,560,000,000
Equity investments	11,804,000		11,905,000
Debt Securities, Held-to-maturity, Sale or Transfer of Investment [Abstract]
Sale of HTM portfolio	0	$ 0
Interest receivable	27,438,000		38,708,000
Debt Securities, Held-to-maturity, Nonaccrual	0		0
Debt Securities, Held-to-maturity, Past Due	0		0
FHLB stock with other-than-temporary impairment	0
Other-than-temporarily impaired equity investments	0
Available-for-sale Securities
Debt Securities, Held-to-maturity, Sale or Transfer of Investment [Abstract]
Interest receivable	13,400,000		22,000,000
Held-to-maturity Securities
Debt Securities, Held-to-maturity, Sale or Transfer of Investment [Abstract]
Interest receivable	$ 259,000		$ 298,000

Loans and Allowance for Loan _3

Loans and Allowance for Loan Losses - Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Loans and Leases Receivable Disclosure [Abstract]
Loans	$ 3,716,598	$ 3,657,779
Less: Allowance for loan losses	41,454	49,006	$ 53,638	$ 24,797
Total loans	3,675,144	3,608,773
Construction Real Estate Loans
Loans and Leases Receivable Disclosure [Abstract]
Loans	605,677	581,941
Less: Allowance for loan losses	8,201	6,490	9,654	3,539
1-4 Family Residential Real Estate Loans
Loans and Leases Receivable Disclosure [Abstract]
Loans	700,430	719,952
Less: Allowance for loan losses	2,508	2,270	2,640	3,833
Commercial Real Estate Loans
Loans and Leases Receivable Disclosure [Abstract]
Loans	1,348,551	1,295,746
Less: Allowance for loan losses	27,236	35,709	36,120	9,572
Commercial loans
Loans and Leases Receivable Disclosure [Abstract]
Loans	564,745	557,122
Less: Allowance for loan losses	3,108	4,107	4,519	6,351
Municipal loans
Loans and Leases Receivable Disclosure [Abstract]
Loans	406,377	409,028
Less: Allowance for loan losses	46	46	47	570
Loans to individuals
Loans and Leases Receivable Disclosure [Abstract]
Loans	90,818	93,990
Less: Allowance for loan losses	$ 355	$ 384	$ 658	$ 932

Loans and Allowance for Loan _4

Loans and Allowance for Loan Losses - Loans by Credit Quality Indicator and Origination Year (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 367,033	$ 1,030,002
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	890,010	779,358
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	713,390	370,505
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	343,496	389,723
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	371,569	199,634
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	750,939	627,713
Revolving Loans Amortized Cost Basis	280,161	260,844
Loans	3,716,598	3,657,779
Construction Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	26,255	155,693
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	160,527	180,918
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	182,708	76,152
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	75,317	55,636
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	33,261	3,214
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	9,130	8,535
Revolving Loans Amortized Cost Basis	118,479	101,793
Loans	605,677	581,941
Construction Real Estate Loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	26,255	155,693
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	160,527	180,536
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	182,708	76,090
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	75,258	55,636
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	33,261	3,191
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	8,877	8,297
Revolving Loans Amortized Cost Basis	118,479	101,793
Loans	605,365	581,236
Construction Real Estate Loans | Pass Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	23
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	22	0
Revolving Loans Amortized Cost Basis	0	0
Loans	22	23
Construction Real Estate Loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Revolving Loans Amortized Cost Basis	0	0
Loans	0	0
Construction Real Estate Loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	382
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	62
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	54	58
Revolving Loans Amortized Cost Basis	0	0
Loans	54	502
Construction Real Estate Loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	59	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	177	180
Revolving Loans Amortized Cost Basis	0	0
Loans	236	180
1-4 Family Residential Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	39,467	155,476
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	152,933	114,063
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	104,065	70,756
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	63,999	56,020
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	47,669	59,638
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	289,697	261,070
Revolving Loans Amortized Cost Basis	2,600	2,929
Loans	700,430	719,952
1-4 Family Residential Real Estate Loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	39,457	154,003
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	151,235	114,063
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	104,065	70,621
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	63,864	55,557
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	46,692	57,680
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	283,115	255,003
Revolving Loans Amortized Cost Basis	2,506	2,833
Loans	690,934	709,760
1-4 Family Residential Real Estate Loans | Pass Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	267
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	823	564
Revolving Loans Amortized Cost Basis	0	0
Loans	823	831
1-4 Family Residential Real Estate Loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	65	10
Revolving Loans Amortized Cost Basis	0	0
Loans	65	10
1-4 Family Residential Real Estate Loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	10	1,473
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,684	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	135
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	427
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	943	1,588
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,289	5,134
Revolving Loans Amortized Cost Basis	94	96
Loans	8,020	8,853
1-4 Family Residential Real Estate Loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	14	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	135	36
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	34	103
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	405	359
Revolving Loans Amortized Cost Basis	0	0
Loans	588	498
Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	165,052	282,184
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	242,082	340,181
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	294,521	155,468
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	142,692	202,510
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	219,216	105,759
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	278,131	202,687
Revolving Loans Amortized Cost Basis	6,857	6,957
Loans	1,348,551	1,295,746
Commercial Real Estate Loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	138,805	270,087
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	236,874	307,161
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	285,638	143,177
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	110,462	162,180
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	181,077	98,828
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	247,524	179,919
Revolving Loans Amortized Cost Basis	6,857	6,957
Loans	1,207,237	1,168,309
Commercial Real Estate Loans | Pass Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	3,153
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	23,272	40,125
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	37,938	1,696
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,472	2,582
Revolving Loans Amortized Cost Basis	0	0
Loans	66,682	47,556
Commercial Real Estate Loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	24,142	4,555
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	577	33,020
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	8,883	7,041
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	7,002	140
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	138	4,531
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	12,245	7,850
Revolving Loans Amortized Cost Basis	0	0
Loans	52,987	57,137
Commercial Real Estate Loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	2,105	7,542
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,631	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	2,097
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,956	65
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	63	704
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	12,756	12,282
Revolving Loans Amortized Cost Basis	0	0
Loans	21,511	22,690
Commercial Real Estate Loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	134	54
Revolving Loans Amortized Cost Basis	0	0
Loans	134	54
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	108,713	317,306
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	224,968	50,707
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	44,606	24,177
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	21,169	9,586
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	7,924	3,679
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	8,665	6,407
Revolving Loans Amortized Cost Basis	148,700	145,260
Loans	564,745	557,122
Commercial loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	108,205	313,688
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	221,819	47,446
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	41,605	20,386
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	17,819	7,505
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	6,368	3,392
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	8,280	6,142
Revolving Loans Amortized Cost Basis	146,516	140,018
Loans	550,612	538,577
Commercial loans | Pass Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	43	2,599
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,313	1,318
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,199	2,410
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2,004	1,981
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,487	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Revolving Loans Amortized Cost Basis	378	370
Loans	7,424	8,678
Commercial loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	280	304
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	809
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	718	433
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	416	39
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	36	286
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	385	265
Revolving Loans Amortized Cost Basis	320	455
Loans	2,155	2,591
Commercial loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	185	405
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	454	1,081
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	989	473
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	481	7
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Revolving Loans Amortized Cost Basis	1,486	4,417
Loans	3,597	6,383
Commercial loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	310
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	382	53
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	95	475
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	449	54
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	31	1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Revolving Loans Amortized Cost Basis	0	0
Loans	957	893
Municipal loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	14,748	72,542
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	69,822	68,132
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	66,741	33,735
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	32,166	61,170
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	59,756	25,387
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	163,144	148,062
Revolving Loans Amortized Cost Basis	0	0
Loans	406,377	409,028
Municipal loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	14,748	72,542
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	69,822	68,132
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	66,741	33,735
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	32,166	61,170
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	59,756	25,387
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	163,144	148,062
Revolving Loans Amortized Cost Basis	0	0
Loans	406,377	409,028
Municipal loans | Pass Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Revolving Loans Amortized Cost Basis	0	0
Loans	0	0
Municipal loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Revolving Loans Amortized Cost Basis	0	0
Loans	0	0
Municipal loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Revolving Loans Amortized Cost Basis	0	0
Loans	0	0
Municipal loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Revolving Loans Amortized Cost Basis	0	0
Loans	0	0
Loans to individuals
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	12,798	46,801
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	39,678	25,357
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	20,749	10,217
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	8,153	4,801
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3,743	1,957
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,172	952
Revolving Loans Amortized Cost Basis	3,525	3,905
Loans	90,818	93,990
Loans to individuals | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	12,798	46,722
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	39,592	25,302
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	20,715	10,132
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	8,079	4,716
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3,672	1,867
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,079	917
Revolving Loans Amortized Cost Basis	3,521	3,900
Loans	90,456	93,556
Loans to individuals | Pass Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Revolving Loans Amortized Cost Basis	0	0
Loans	0	0
Loans to individuals | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	51
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	47	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Revolving Loans Amortized Cost Basis	4	4
Loans	51	55
Loans to individuals | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	6
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	19	35
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	34	28
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	22	30
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	27	9
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	10	11
Revolving Loans Amortized Cost Basis	0	1
Loans	112	120
Loans to individuals | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	73
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	67	20
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	6
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	5	55
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	44	81
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	83	24
Revolving Loans Amortized Cost Basis	0	0
Loans	$ 199	$ 259

Loans and Allowance for Loan _5

Loans and Allowance for Loan Losses - Aging of Past Due Loans by Class of Loan (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 15,071	$ 21,587
Current	3,701,527	3,636,192
Total loans	3,716,598	3,657,779
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	13,052	10,440
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	889	7,437
Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	1,130	3,710
Construction Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	1,130	553
Current	604,547	581,388
Total loans	605,677	581,941
Construction Real Estate Loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	1,130	95
Construction Real Estate Loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	0	14
Construction Real Estate Loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	0	444
1-4 Family Residential Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	6,421	13,171
Current	694,009	706,781
Total loans	700,430	719,952
1-4 Family Residential Real Estate Loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	5,321	7,872
1-4 Family Residential Real Estate Loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	614	2,469
1-4 Family Residential Real Estate Loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	486	2,830
Commercial Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	4,676	868
Current	1,343,875	1,294,878
Total loans	1,348,551	1,295,746
Commercial Real Estate Loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	4,676	467
Commercial Real Estate Loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	0	315
Commercial Real Estate Loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	0	86
Commercial loans
Financing Receivable, Past Due [Line Items]
Total Past Due	2,393	6,262
Current	562,352	550,860
Total loans	564,745	557,122
Commercial loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	1,507	1,423
Commercial loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	245	4,516
Commercial loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	641	323
Municipal loans
Financing Receivable, Past Due [Line Items]
Total Past Due	0	64
Current	406,377	408,964
Total loans	406,377	409,028
Municipal loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	0	64
Municipal loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Municipal loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Loans to individuals
Financing Receivable, Past Due [Line Items]
Total Past Due	451	669
Current	90,367	93,321
Total loans	90,818	93,990
Loans to individuals | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	418	519
Loans to individuals | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	30	123
Loans to individuals | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 3	$ 27

Loans and Allowance for Loan _6

Loans and Allowance for Loan Losses - Nonperforming Assets by Asset Class (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Nonperforming Assets [Line Items]
Restructured nonaccrual loans		$ 889	$ 976
Nonperforming Assets
Nonperforming Assets [Line Items]
Nonaccrual loans	[1]	5,314	7,714
Accruing loans past due more than 90 days		0	0
TDR loans		9,641	9,646
OREO		412	106
Repossessed assets		0	14
Total nonperforming assets		15,367	17,480
Nonperforming Assets | Construction Real Estate Loans
Nonperforming Assets [Line Items]
Nonaccrual loans		248	640
Nonperforming Assets | 1-4 Family Residential Real Estate Loans
Nonperforming Assets [Line Items]
Nonaccrual loans		1,929	3,922
Nonperforming Assets | Commercial Real Estate Loans
Nonperforming Assets [Line Items]
Nonaccrual loans		1,229	1,269
Nonperforming Assets | Commercial loans
Nonperforming Assets [Line Items]
Nonaccrual loans		1,682	1,592
Nonperforming Assets | Loans to individuals
Nonperforming Assets [Line Items]
Nonaccrual loans		$ 226	$ 291
[1]	Includes $889,000 and $976,000 of restructured loans as of March 31, 2021 and December 31, 2020, respectively.

Loans and Allowance for Loan _7

Loans and Allowance for Loan Losses - Troubled Debt Restructurings (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)contract	Mar. 31, 2020USD ($)contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | contract	3	2
Total Modifications	$ 148	$ 62
1-4 Family Residential Real Estate Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | contract	2
Total Modifications	$ 130
Commercial Real Estate Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | contract		1
Total Modifications		$ 59
Commercial loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | contract	1	1
Total Modifications	$ 18	$ 3
Extended Amortization Period
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications	0	0
Extended Amortization Period | 1-4 Family Residential Real Estate Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications	0
Extended Amortization Period | Commercial Real Estate Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications		0
Extended Amortization Period | Commercial loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications	0	0
Interest Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications	0	0
Interest Rate Reduction | 1-4 Family Residential Real Estate Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications	0
Interest Rate Reduction | Commercial Real Estate Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications		0
Interest Rate Reduction | Commercial loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications	0	0
Combination
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications	148	62
Combination | 1-4 Family Residential Real Estate Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications	130
Combination | Commercial Real Estate Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications		59
Combination | Commercial loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Modifications	$ 18	$ 3

Loans and Allowance for Loan _8

Loans and Allowance for Loan Losses - Allowance for Loan Losses Activity by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period	$ 49,006	$ 24,797
Loans charged-off	(795)	(995)
Recoveries of loans charged-off	622	451
Net loans (charged-off) recovered	(173)	(544)
Provision for (reversal of) loan losses	(7,379)	24,082	[1]
Balance at end of period	41,454	53,638
Construction Real Estate Loans
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period	6,490	3,539
Loans charged-off	0	(33)
Recoveries of loans charged-off	1	11
Net loans (charged-off) recovered	1	(22)
Provision for (reversal of) loan losses	1,710	3,184	[1]
Balance at end of period	8,201	9,654
1-4 Family Residential Real Estate Loans
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period	2,270	3,833
Loans charged-off	(73)	(54)
Recoveries of loans charged-off	55	4
Net loans (charged-off) recovered	(18)	(50)
Provision for (reversal of) loan losses	256	310	[1]
Balance at end of period	2,508	2,640
Commercial Real Estate Loans
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period	35,709	9,572
Loans charged-off	0	(21)
Recoveries of loans charged-off	0	69
Net loans (charged-off) recovered	0	48
Provision for (reversal of) loan losses	(8,473)	18,437	[1]
Balance at end of period	27,236	36,120
Commercial loans
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period	4,107	6,351
Loans charged-off	(319)	(296)
Recoveries of loans charged-off	282	74
Net loans (charged-off) recovered	(37)	(222)
Provision for (reversal of) loan losses	(962)	1,944	[1]
Balance at end of period	3,108	4,519
Municipal loans
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period	46	570
Loans charged-off	0	0
Recoveries of loans charged-off	0	0
Net loans (charged-off) recovered	0	0
Provision for (reversal of) loan losses	0	(1)	[1]
Balance at end of period	46	47
Loans to individuals
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period	384	932
Loans charged-off	(403)	(591)
Recoveries of loans charged-off	284	293
Net loans (charged-off) recovered	(119)	(298)
Provision for (reversal of) loan losses	90	208	[1]
Balance at end of period	$ 355	658
Impact of CECL adoption
Allowances for Loan Losses [Roll Forward]
Impact of CECL adoption - cumulative effect adjustment		5,072
Impact of CECL adoption - purchased loans with credit deterioration		231
Impact of CECL adoption | Construction Real Estate Loans
Allowances for Loan Losses [Roll Forward]
Impact of CECL adoption - cumulative effect adjustment		2,968
Impact of CECL adoption - purchased loans with credit deterioration		(15)
Impact of CECL adoption | 1-4 Family Residential Real Estate Loans
Allowances for Loan Losses [Roll Forward]
Impact of CECL adoption - cumulative effect adjustment		(1,447)
Impact of CECL adoption - purchased loans with credit deterioration		(6)
Impact of CECL adoption | Commercial Real Estate Loans
Allowances for Loan Losses [Roll Forward]
Impact of CECL adoption - cumulative effect adjustment		7,730
Impact of CECL adoption - purchased loans with credit deterioration		333
Impact of CECL adoption | Commercial loans
Allowances for Loan Losses [Roll Forward]
Impact of CECL adoption - cumulative effect adjustment		(3,532)
Impact of CECL adoption - purchased loans with credit deterioration		(22)
Impact of CECL adoption | Municipal loans
Allowances for Loan Losses [Roll Forward]
Impact of CECL adoption - cumulative effect adjustment		(522)
Impact of CECL adoption - purchased loans with credit deterioration		0
Impact of CECL adoption | Loans to individuals
Allowances for Loan Losses [Roll Forward]
Impact of CECL adoption - cumulative effect adjustment		(125)
Impact of CECL adoption - purchased loans with credit deterioration		$ (59)
[1]	The increase in the provision for credit losses during 2020 was primarily due to the economic impact of COVID-19 on macroeconomic factors used in the CECL model.

Loans and Allowance for Loan _9

Loans and Allowance for Loan Losses - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Interest receivable	$ 27,438,000		$ 38,708,000
TDRs restructured	148,000	$ 62,000
Reversal of interest income on nonaccrual loans	18,000	121,000
Nonaccrual loans, no allowance	1,600,000		2,200,000
Loans	3,716,598,000		3,657,779,000
Collateral-dependent loans	11,200,000		11,500,000
Allowance for Credit Loss	41,454,000	53,638,000	49,006,000	$ 24,797,000
Loans in process of foreclosure	234,000		1,200,000
Commitments to lend additional funds on Troubled Debt Restructurings (TDR)	0	0
COVID-19 Payment Deferral
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	1,700,000		47,200,000
Commercial Real Estate Loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Owner and nonowner-occupied real estate	1,250,000,000
Loans secured by multi-family properties	81,600,000
Loans secured by farmland	15,000,000
TDRs restructured		59,000
Loans	$ 1,348,551,000		1,295,746,000
General Loan Term	20 years
Allowance for Credit Loss	$ 27,236,000	36,120,000	35,709,000	9,572,000
1-4 Family Residential Real Estate Loans
Financing Receivable, Allowance for Credit Loss [Line Items]
TDRs restructured	130,000
Loans	700,430,000		719,952,000
Allowance for Credit Loss	$ 2,508,000	2,640,000	2,270,000	3,833,000
1-4 Family Residential Real Estate Loans | Minimum
Financing Receivable, Allowance for Credit Loss [Line Items]
General Loan Term	5 years
1-4 Family Residential Real Estate Loans | Maximum
Financing Receivable, Allowance for Credit Loss [Line Items]
General Loan Term	30 years
Paycheck Protection Program
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	$ 220,900,000		214,800,000
Allowance for Credit Loss	0
Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
TDRs restructured	18,000	3,000
Loans	564,745,000		557,122,000
Allowance for Credit Loss	3,108,000	$ 4,519,000	4,107,000	$ 6,351,000
Loan portfolio
Financing Receivable, Allowance for Credit Loss [Line Items]
Interest receivable	$ 13,800,000		$ 16,400,000

Borrowing Arrangements (Details

Borrowing Arrangements (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Other borrowings		$ 22,315	$ 23,172
FHLB borrowings		665,530	832,527
Other borrowings:
Debt Instrument [Line Items]
Other borrowings		22,315	23,172
Average amount outstanding during the period	[1]	23,522	91,940
Maximum amount outstanding during the period	[2]	$ 24,549	$ 219,259
Weighted average interest rate during the period	[3]	0.20%	0.40%
Interest rate at end of the period	[4]	0.20%	0.10%
FHLB borrowings:
Debt Instrument [Line Items]
FHLB borrowings		$ 665,530	$ 832,527
Average amount outstanding during the period	[1]	727,513	1,032,269
Maximum amount outstanding during the period	[2]	$ 723,584	$ 1,274,370
Weighted average interest rate during the period	[3]	1.10%	1.10%
Interest rate at end of the period	[4]	1.10%	1.00%
[1]	The average amount outstanding during the period was computed by dividing the total daily outstanding principal balances by the number of days in the period.
[2]	The maximum amount outstanding at any month-end during the period.
[3]	The weighted average interest rate during the period was computed by dividing the actual interest expense (annualized for interim periods) by the average amount outstanding during the period. The weighted average interest rate on the FHLB borrowings includes the effect of interest rate swaps.
[4]	Stated rate.

Borrowings Maturities Table (De

Borrowings Maturities Table (Details) $ in Thousands	Mar. 31, 2021USD ($)
Debt Instrument [Line Items]
Less than 1 Year	$ 683,974
1-2 Years	687
2-3 Years	717
3-4 Years	748
4-5 Years	775
Thereafter	944
Total	687,845
Other borrowings:
Debt Instrument [Line Items]
Less than 1 Year	22,315
1-2 Years	0
2-3 Years	0
3-4 Years	0
4-5 Years	0
Thereafter	0
Total	22,315
FHLB borrowings:
Debt Instrument [Line Items]
Less than 1 Year	661,659
1-2 Years	687
2-3 Years	717
3-4 Years	748
4-5 Years	775
Thereafter	944
Total	$ 665,530

Borrowing Arrangements Narrativ

Borrowing Arrangements Narrative (Details)	3 Months Ended
	Mar. 31, 2021USD ($)agreementoustanding_letters_of_creditcredit_lineRate	Dec. 31, 2020USD ($)
Line of Credit Facility [Line Items]
Number of credit lines maintained by the Company | credit_line	3
Carrying value of investment securities pledged as collateral	$ 1,470,000,000	$ 1,560,000,000
Federal funds purchased	0	0
Letters of Credit, Federal Home Loan Bank, as collateral	$ 0
Maturity of repurchase agreements (less than)	1 year
Securities sold under repurchase agreements	$ 22,300,000	23,200,000
Federal Home Loan Bank borrowings, additional funding available	1,250,000,000
Borrowings with variable interest rate, face amount	625,000,000
Frost Bank
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	40,000,000
Line of credit, capacity available for issuance of letters of credit	$ 5,000,000
Number of outstanding letters of credit | oustanding_letters_of_credit	1
Letters of Credit Outstanding, Amount	$ 91,000
TIB - The Independent Bankers Bank
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	15,000,000
Comerica Bank
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	7,500,000
Federal Reserve Discount Window
Line of Credit Facility [Line Items]
Additional funding available	$ 618,100,000
Minimum
Line of Credit Facility [Line Items]
Federal Home Loan Bank borrowings interest rates	0.08%
Federal Home Loan Bank borrowings maturities	5 days
Maximum
Line of Credit Facility [Line Items]
Federal Home Loan Bank borrowings interest rates	4.799%
Federal Home Loan Bank borrowings maturities	7 years 3 months 18 days
Variable Rate Agreements and Fixed Short-term Pay Agreements
Line of Credit Facility [Line Items]
Borrowings with variable interest rate, face amount	$ 625,000,000	670,000,000
Three-Month London Interbank Offered Rate (LIBOR) | Variable Rate Agreements and Fixed Short-term Pay Agreements
Line of Credit Facility [Line Items]
Description of variable and fixed rate basis	three-month LIBOR
Three-Month London Interbank Offered Rate (LIBOR) | Variable Rate Agreements and Fixed Short-term Pay Agreements | Maximum
Line of Credit Facility [Line Items]
Debt Instrument, Number Of Variable Rate Advance Agreements | agreement	6
One-Month London Interbank Offered Rate (LIBOR) | Variable Rate Agreements and Fixed Short-term Pay Agreements
Line of Credit Facility [Line Items]
Description of variable and fixed rate basis	one-month LIBOR
Cash flow hedging | Variable Rate Agreements and Fixed Short-term Pay Agreements
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate During Period | Rate	1.11%
Derivative, Average Remaining Maturity	3 years 9 months 18 days
Federal Reserve Discount Window
Line of Credit Facility [Line Items]
Other borrowings	$ 0	$ 0

Long-term Debt Other Long-term

Long-term Debt Other Long-term Debt (Details) - USD ($) $ in Thousands

3 Months Ended

Mar. 31, 2021

Dec. 31, 2020

Nov. 06, 2020

Sep. 19, 2016

Oct. 10, 2007

[5]

Aug. 10, 2007

Aug. 08, 2007

Sep. 04, 2003

Debt Instruments [Abstract]

Subordinated notes, net of unamortized debt issuance costs:

[1]

$ 197,268

$ 197,251

Trust preferred subordinated debentures

[2]

60,256

60,255

Total long-term debt

257,524

257,506

5.50% Subordinated Notes

Debt Instruments [Abstract]

Subordinated notes, net of unamortized debt issuance costs:

[1],[3]

98,799

98,754

Unamortized Debt Issuance Expense

$ 1,200

1,200

Stated interest rate

5.50%

5.50%

Southside Statutory Trust III, net of unamortized debt issuance costs

Debt Instruments [Abstract]

Trust preferred subordinated debentures

$ 20,564

[2],[4]

20,563

[2],[4]

$ 20,619

Unamortized Debt Issuance Expense

55

56

Southside Statutory Trust IV

Debt Instruments [Abstract]

Trust preferred subordinated debentures

23,196

[2]

23,196

[2]

$ 23,196

Southside Statutory Trust V

Debt Instruments [Abstract]

Trust preferred subordinated debentures

12,887

[2]

12,887

[2]

$ 12,887

Magnolia Trust Company I

Debt Instruments [Abstract]

Trust preferred subordinated debentures

3,609

[2]

3,609

[2]

$ 3,609

3.875% Subordinated Notes

Debt Instruments [Abstract]

Subordinated notes, net of unamortized debt issuance costs:

[1],[6]

98,469

98,497

Unamortized Debt Issuance Expense

$ 1,500

$ 1,500

Stated interest rate

3.875%

3.875%

Minimum | 5.50% Subordinated Notes

Debt Instruments [Abstract]

Long-term debt, remaining maturity, greater than

1 year

[1]

This debt consists of subordinated notes with a remaining maturity greater than one year that qualify under the risk-based capital guidelines as Tier 2 capital, subject to certain limitations.

[2]

This debt consists of trust preferred securities that qualify under the risk-based capital guidelines as Tier 1 capital, subject to certain limitations.

[3]

The unamortized discount and debt issuance costs reflected in the carrying amount of the subordinated notes totaled approximately $1.2 million at March 31, 2021 and December 31, 2020.

[4]

The unamortized debt issuance costs reflected in the carrying amount of the Southside Statutory Trust III junior subordinated debentures totaled $55,000 at March 31, 2021 and $56,000 at December 31, 2020.

[5]

On October 10, 2007, as part of an acquisition we assumed $3.6 million of floating rate junior subordinated debentures issued in 2005 to Magnolia Trust Company I.

[6]

The unamortized discount and debt issuance costs reflected in the carrying amount of the subordinated notes totaled approximately $1.5 million at March 31, 2021 and December 31, 2020.

Long-term Debt LT Debt Interest

Long-term Debt LT Debt Interest Rates (Details) - USD ($) $ in Thousands

Nov. 14, 2025

Sep. 30, 2021

Nov. 06, 2020

Sep. 19, 2016

Oct. 10, 2007

Aug. 10, 2007

Aug. 08, 2007

Sep. 04, 2003

Mar. 31, 2021

Dec. 31, 2020

Debt Instrument [Line Items]

Other long-term debt

[1]

$ 60,256

$ 60,255

5.50% Subordinated Notes

Debt Instrument [Line Items]

Amount issued

$ 100,000

Stated interest rate

5.50%

5.50%

Southside Statutory Trust III

Debt Instrument [Line Items]

Other long-term debt

$ 20,619

$ 20,564

[1],[2]

20,563

[1],[2]

Southside Statutory Trust III | Three-Month London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Basis on variable rate

2.94%

Southside Statutory Trust IV

Debt Instrument [Line Items]

Other long-term debt

$ 23,196

23,196

[1]

23,196

[1]

Southside Statutory Trust IV | Three-Month London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Basis on variable rate

1.30%

Southside Statutory Trust V

Debt Instrument [Line Items]

Other long-term debt

$ 12,887

12,887

[1]

12,887

[1]

Southside Statutory Trust V | Three-Month London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Basis on variable rate

2.25%

Magnolia Trust Company I

Debt Instrument [Line Items]

Other long-term debt

$ 3,609

[3]

$ 3,609

[1]

$ 3,609

[1]

Magnolia Trust Company I | Three-Month London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Basis on variable rate

1.80%

3.875% Subordinated Notes

Debt Instrument [Line Items]

Amount issued

$ 100,000

Stated interest rate

3.875%

3.875%

Forecast | 5.50% Subordinated Notes | Three-Month London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Basis on variable rate

4.297%

Forecast | 3.875% Subordinated Notes | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate

Debt Instrument [Line Items]

Basis on variable rate

3.66%

[1]

This debt consists of trust preferred securities that qualify under the risk-based capital guidelines as Tier 1 capital, subject to certain limitations.

[2]

The unamortized debt issuance costs reflected in the carrying amount of the Southside Statutory Trust III junior subordinated debentures totaled $55,000 at March 31, 2021 and $56,000 at December 31, 2020.

[3]

On October 10, 2007, as part of an acquisition we assumed $3.6 million of floating rate junior subordinated debentures issued in 2005 to Magnolia Trust Company I.

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 423
Interest cost	628	837
Expected return on assets	(1,437)	(1,668)
Net loss amortization	520	533
Prior service (credit) cost amortization	0	(3)
Net periodic benefit cost (income)	(289)	122
Defined Benefit Pension Plan Acquired
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	24	41
Expected return on assets	(58)	(84)
Net loss amortization	3	2
Prior service (credit) cost amortization	0	0
Net periodic benefit cost (income)	(31)	(41)
Restoration Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	85
Interest cost	121	160
Expected return on assets	0	0
Net loss amortization	118	193
Prior service (credit) cost amortization	0	2
Net periodic benefit cost (income)	$ 239	$ 440

Derivative Financial Instrume_3

Derivative Financial Instruments and Hedging Activities - Schedule Of Derivative Instruments (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Asset Derivative
Gross derivatives		$ 14,035	$ 18,537
Offsetting derivative assets		(3,055)	0
Cash collateral received/posted		0	0
Net derivatives included in the consolidated balance sheets	[1]	10,980	18,537
Liability Derivative
Gross derivatives		23,079	40,172
Offsetting derivative liabilities		(3,055)	0
Cash collateral received/posted		(19,114)	(39,270)
Net derivatives included in the consolidated balance sheets	[1]	910	902
Financial Institution Counterparties
Derivatives, Fair Value [Line Items]
Credit exposure related to interest rate swaps		1,300	0
Financial Institution Counterparties | Designated as Hedging Instrument | Cash Flow Hedging | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[2]	625,000	670,000
Asset Derivative
Gross derivatives		2,145	0
Liability Derivative
Gross derivatives		11,189	21,635
Financial Institution Counterparties | Not Designated as Hedging Instrument | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[2]	217,655	152,280
Asset Derivative
Gross derivatives		910	0
Liability Derivative
Gross derivatives		10,980	18,537
Customer Counterparties
Derivatives, Fair Value [Line Items]
Credit exposure related to interest rate swaps		11,000	18,500
Customer Counterparties | Not Designated as Hedging Instrument | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[2]	217,655	152,280
Asset Derivative
Gross derivatives		10,980	18,537
Liability Derivative
Gross derivatives		$ 910	$ 0
[1]	Net derivative assets are included in other assets and net derivative liabilities are included in other liabilities on the consolidated balance sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and our credit risk. We had $1.3 million credit exposure related to interest rate swaps with financial institutions and $11.0 million related to interest rate swaps with customers at March 31, 2021. We had no credit exposure related to interest rate swaps with financial institutions and $18.5 million related to interest rate swaps with customers at
[2]	Notional amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the consolidated balance sheets.

Derivative Financial Instrume_4

Derivative Financial Instruments and Hedging Activities - Weighted Average Remaining Maturity, Lives, and Rates of Interest Rate Swaps (Details) - Interest Rate Swap - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2021	Dec. 31, 2020
Financial Institution Counterparties | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Notional Amount	[1]	$ 217,655	$ 152,280
Remaining Maturity		11 years	9 years 9 months 18 days
Weighted Average Receive Rate		0.52%	0.50%
Weighted Average Pay Rate		2.43%	2.57%
Financial Institution Counterparties | Cash Flow Hedging | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Notional Amount	[1]	$ 625,000	$ 670,000
Remaining Maturity		3 years 9 months 18 days	3 years 9 months 18 days
Weighted Average Receive Rate		0.14%	0.17%
Weighted Average Pay Rate		1.11%	1.12%
Customer Counterparties | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Notional Amount	[1]	$ 217,655	$ 152,280
Remaining Maturity		11 years	9 years 9 months 18 days
Weighted Average Receive Rate		2.43%	2.57%
Weighted Average Pay Rate		0.52%	0.50%
[1]	Notional amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the consolidated balance sheets.

Derivative Financial Instrume_5

Derivative Financial Instruments and Hedging Activities - Narrative (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Debt face amount	$ 625,000,000
Cash collateral held by counterparties subject to master netting agreements	19,100,000	$ 39,300,000
Cash collateral receivable that was not offset against derivative liabilities	$ 1,300,000

Fair Value Measurement - Recurr

Fair Value Measurement - Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		$ 2,546,924	$ 2,587,305
Derivative assets	[1]	10,980	18,537
Derivative liabilities	[1]	910	902
US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		42,477
State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		1,591,645	1,580,594
Other stocks and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		92,783	78,255
Residential MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	[2]	707,074	810,010
Commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	[2]	112,945	118,446
Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments		5,988	6,094
Total asset fair value measurements		2,566,947	2,611,936
Total liability fair value measurements		23,079	40,172
Fair Value, Recurring | US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		42,477
Fair Value, Recurring | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		1,591,645	1,580,594
Fair Value, Recurring | Other stocks and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		92,783	78,255
Fair Value, Recurring | Residential MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	[3]	707,074	810,010
Fair Value, Recurring | Commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	[3]	112,945	118,446
Fair Value, Recurring | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		14,035	18,537
Derivative liabilities		23,079	40,172
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments		5,988	6,094
Total asset fair value measurements		48,465	6,094
Total liability fair value measurements		0	0
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		42,477
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		0	0
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other stocks and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		0	0
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	[3]	0	0
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	[3]	0	0
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Fair Value, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments		0	0
Total asset fair value measurements		2,518,482	2,605,842
Total liability fair value measurements		23,079	40,172
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		0
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		1,591,645	1,580,594
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Other stocks and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		92,783	78,255
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Residential MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	[3]	707,074	810,010
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	[3]	112,945	118,446
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		14,035	18,537
Derivative liabilities		23,079	40,172
Fair Value, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments		0	0
Total asset fair value measurements		0	0
Total liability fair value measurements		0	0
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		0
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		0	0
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Other stocks and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value		0	0
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Residential MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	[3]	0	0
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	[3]	0	0
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed assets		412	120
Total asset fair value measurements		10,635	10,773
Fair Value, Nonrecurring | Collateral-dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral-dependent loans	[4]	10,223	10,653
Fair Value, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed assets		0	0
Total asset fair value measurements		0	0
Fair Value, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Collateral-dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral-dependent loans	[4]	0	0
Fair Value, Nonrecurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed assets		0	0
Total asset fair value measurements		0	0
Fair Value, Nonrecurring | Significant Other Observable Inputs (Level 2) | Collateral-dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral-dependent loans	[4]	0	0
Fair Value, Nonrecurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed assets		412	120
Total asset fair value measurements		10,635	10,773
Fair Value, Nonrecurring | Significant Unobservable Inputs (Level 3) | Collateral-dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral-dependent loans	[4]	$ 10,223	$ 10,653
[1]	Net derivative assets are included in other assets and net derivative liabilities are included in other liabilities on the consolidated balance sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and our credit risk. We had $1.3 million credit exposure related to interest rate swaps with financial institutions and $11.0 million related to interest rate swaps with customers at March 31, 2021. We had no credit exposure related to interest rate swaps with financial institutions and $18.5 million related to interest rate swaps with customers at
[2]	All MBS issued and/or guaranteed by U.S. government agencies or U.S. GSEs.
[3]	All MBS are issued and/or guaranteed by U.S. government agencies or U.S. GSEs.
[4]	Consists of individually evaluated loans. Loans for which the fair value of the collateral and commercial real estate fair value of the properties is less than cost basis are presented net of allowance. Losses on these loans represent charge-offs which are netted against the allowance for loan losses.

Fair Value Measurement - Balanc

Fair Value Measurement - Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Carrying Amount
Financial assets:
Cash and cash equivalents	$ 107,623	$ 108,408
Investment securities:
HTM, at carrying value	908	907
Mortgage-backed securities:
HTM, at carrying value	97,251	108,091
Federal Home Loan Bank stock, at cost	18,754	25,259
Equity investments	5,816	5,811
Loans, net of allowance for loan losses	3,675,144	3,608,773
Loans held for sale	2,615	3,695
Financial liabilities:
Deposits	5,092,643	4,932,322
Other borrowings	22,315	23,172
FHLB borrowings	665,530	832,527
Subordinated notes, net of unamortized debt issuance costs	197,268	197,251
Trust preferred subordinated debentures, net of unamortized debt issuance costs	60,256	60,255
Estimated Fair Value
Financial assets:
Cash and cash equivalents	107,623	108,408
Investment securities:
HTM, at carrying value	917	920
Mortgage-backed securities:
HTM, at carrying value	103,260	117,278
Federal Home Loan Bank stock, at cost	18,754	25,259
Equity investments	5,816	5,811
Loans, net of allowance for loan losses	3,833,854	3,784,291
Loans held for sale	2,615	3,695
Financial liabilities:
Deposits	5,095,397	4,936,188
Other borrowings	22,315	23,172
FHLB borrowings	675,135	854,865
Subordinated notes, net of unamortized debt issuance costs	198,103	198,391
Trust preferred subordinated debentures, net of unamortized debt issuance costs	47,183	51,993
Estimated Fair Value | Level 1
Financial assets:
Cash and cash equivalents	107,623	108,408
Investment securities:
HTM, at carrying value	0	0
Mortgage-backed securities:
HTM, at carrying value	0	0
Federal Home Loan Bank stock, at cost	0	0
Equity investments	0	0
Loans, net of allowance for loan losses	0	0
Loans held for sale	0	0
Financial liabilities:
Deposits	0	0
Other borrowings	0	0
FHLB borrowings	0	0
Subordinated notes, net of unamortized debt issuance costs	0	0
Trust preferred subordinated debentures, net of unamortized debt issuance costs	0	0
Estimated Fair Value | Level 2
Financial assets:
Cash and cash equivalents	0	0
Investment securities:
HTM, at carrying value	917	920
Mortgage-backed securities:
HTM, at carrying value	103,260	117,278
Federal Home Loan Bank stock, at cost	18,754	25,259
Equity investments	5,816	5,811
Loans, net of allowance for loan losses	0	0
Loans held for sale	2,615	3,695
Financial liabilities:
Deposits	5,095,397	4,936,188
Other borrowings	22,315	23,172
FHLB borrowings	675,135	854,865
Subordinated notes, net of unamortized debt issuance costs	198,103	198,391
Trust preferred subordinated debentures, net of unamortized debt issuance costs	47,183	51,993
Estimated Fair Value | Level 3
Financial assets:
Cash and cash equivalents	0	0
Investment securities:
HTM, at carrying value	0	0
Mortgage-backed securities:
HTM, at carrying value	0	0
Federal Home Loan Bank stock, at cost	0	0
Equity investments	0	0
Loans, net of allowance for loan losses	3,833,854	3,784,291
Loans held for sale	0	0
Financial liabilities:
Deposits	0	0
Other borrowings	0	0
FHLB borrowings	0	0
Subordinated notes, net of unamortized debt issuance costs	0	0
Trust preferred subordinated debentures, net of unamortized debt issuance costs	$ 0	$ 0

Fair Value Measurement Narrativ

Fair Value Measurement Narrative (Details)	3 Months Ended
	Mar. 31, 2021source
Available-for-sale Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of third party sources used to validate prices, in some cases	2
Derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of third party sources used to validate prices, in some cases	2

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Current income tax expense	$ 2,589	$ 5,554
Deferred income tax expense (benefit)	2,161	(5,075)
Income tax expense	$ 4,750	$ 479

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Deferred tax liability, net	$ 9,900,000		$ 15,500,000
Deferred tax assets, valuation allowance	0		$ 0
Income tax expense	$ 4,750,000	$ 479,000
Effective income tax rate, percent	12.20%	10.80%

Off-Balance-Sheet Arrangement_3

Off-Balance-Sheet Arrangements, Allowance for off-balance-sheet credit exposures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 6,386	$ 1,455
Provision for (reversal of) off-balance-sheet credit exposures	(2,770)	1,165
Balance at end of period	3,616	7,460
Impact of CECL adoption
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 0	$ 4,840

Off-Balance-Sheet Arrangement_4

Off-Balance-Sheet Arrangements, Commitments and Contingencies (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	$ 822,399	$ 806,796
Commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	811,574	793,138
Standby letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	$ 10,825	$ 13,658

Off-Balance-Sheet Arrangement_5

Off-Balance-Sheet Arrangements, Commitments and Contingencies Narrative (Details)	3 Months Ended
	Mar. 31, 2021USD ($)contract	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Leases:
Operating lease right-of-use assets obtained in exchange for new operating lease liabilities	$ 1,100,000	$ 227,000
Lessee, Operating Lease, Number of Contracts | contract	1
Operating lease ROU assets	$ 15,788,000		$ 15,063,000
Securities:
Unsettled trades to purchase securities	23,473,000	14,596,000	0
Unsettled trades to sell securities	0	$ 67,247,000	0
Deposits:
Unsettled Issuances of Brokered CDs	0		0
Operating Leased Assets [Line Items]
Operating lease ROU assets	15,788,000		$ 15,063,000
Operating lease
Leases:
Operating lease ROU assets	1,100,000
Operating Leased Assets [Line Items]
Operating lease ROU assets	$ 1,100,000