Southside Bancshares (SBSI) 10-Q 28 Apr 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	Apr. 24, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	SOUTHSIDE BANCSHARES INC
Entity Central Index Key	705,432
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		28,586,916

CONSOLIDATED BALANCE SHEETS (UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($)		Mar. 31, 2017	Dec. 31, 2016
ASSETS
Cash and due from banks		$ 54,345,000	$ 59,363,000
Interest earning deposits		185,289,000	102,251,000
Federal funds sold		7,360,000	8,040,000
Total cash and cash equivalents		246,994,000	169,654,000
Securities available for sale, at estimated fair value		1,444,043,000	1,479,600,000
Securities held to maturity, at carrying value (estimated fair value of $940,409 and $944,282, respectively)		929,793,000	937,487,000
FHLB stock, at cost		61,305,000	61,084,000
Other investments		5,442,000	5,508,000
Loans held for sale		5,303,000	7,641,000
Loans:
Loans	[1]	2,538,918,000	2,556,537,000
Less: Allowance for loan losses	[1]	(18,485,000)	(17,911,000)
Net Loans		2,520,433,000	2,538,626,000
Premises and equipment, net		105,327,000	106,003,000
Goodwill		91,520,000	91,520,000
Other intangible assets, net		4,177,000	4,608,000
Interest receivable		18,273,000	25,183,000
Deferred tax asset, net		26,827,000	28,891,000
Unsettled trades to sell securities		57,385,000	0
Unsettled issuances of brokered certificates of deposit		31,232,000	0
Bank owned life insurance		98,377,000	97,775,000
Other assets		9,818,000	10,187,000
Total assets		5,656,249,000	5,563,767,000
Deposits:
Noninterest bearing		753,224,000	704,013,000
Interest bearing		2,952,072,000	2,829,063,000
Total deposits		3,705,296,000	3,533,076,000
Short-term obligations:
Federal funds purchased and repurchase agreements		7,814,000	7,097,000
FHLB advances		952,916,000	866,518,000
Total short-term obligations		960,730,000	873,615,000
Long-term obligations:
FHLB advances		252,940,000	443,128,000
Subordinated notes, net of unamortized debt issuance costs		98,133,000	98,100,000
Long-term debt, net of unamortized debt issuance costs		60,237,000	60,236,000
Total long-term obligations		411,310,000	601,464,000
Unsettled trades to purchase securities		10,465,000	160,000
Other liabilities		36,982,000	37,178,000
Total liabilities		5,124,783,000	5,045,493,000
Off-balance-sheet arrangements, commitments and contingencies (Note 11)
Shareholders’ equity:
Common stock ($1.25 par value, 40,000,000 shares authorized, 31,499,980 shares issued at March 31, 2017 and 31,455,951 shares issued at December 31, 2016)		39,375,000	39,320,000
Paid-in capital		536,653,000	535,240,000
Retained earnings		37,920,000	30,098,000
Treasury stock, at cost (2,913,064 shares at March 31, 2017 and December 31, 2016)		(47,891,000)	(47,891,000)
Accumulated other comprehensive loss		(34,591,000)	(38,493,000)
Total shareholders’ equity		531,466,000	518,274,000
Total liabilities and shareholders’ equity		$ 5,656,249,000	$ 5,563,767,000
[1]	Includes approximately $324.9 million and $372.4 million of loans acquired with the Omni acquisition as of March 31, 2017 and December 31, 2016, respectively.

CONSOLIDATED BALANCE SHEETS (U3

CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Held-to-maturity Securities, Other Disclosure Items [Abstract]
Securities held to maturity, fair value	$ 940,409	$ 944,282
Shareholders' equity:
Common stock, par value (in dollars per share)	$ 1.25	$ 1.25
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	31,499,980	31,455,951
Treasury stock (in shares)	2,913,064	2,913,064

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Interest income
Loans	$ 27,254	$ 27,765
Investment securities – taxable	377	214
Investment securities – tax-exempt	6,554	5,355
Mortgage-backed securities	10,045	9,391
FHLB stock and other investments	298	217
Other interest earning assets	360	70
Total interest income	44,888	43,012
Interest expense
Deposits	4,281	3,256
Short-term obligations	2,065	696
Long-term obligations	3,262	2,444
Total interest expense	9,608	6,396
Net interest income	35,280	36,616
Provision for loan losses	1,098	2,316
Net interest income after provision for loan losses	34,182	34,300
Noninterest income
Deposit services	5,114	5,085
Net gain on sale of securities available for sale	322	2,441
Gain on sale of loans	701	643
Trust income	890	855
Bank owned life insurance income	634	674
Brokerage services	547	575
Other	1,465	1,323
Total noninterest income	9,673	11,596
Noninterest expense
Salaries and employee benefits	15,919	17,732
Occupancy expense	2,863	3,335
Advertising, travel & entertainment	583	685
ATM and debit card expense	927	712
Professional fees	939	1,338
Software and data processing expense	725	749
Telephone and communications	526	484
FDIC insurance	441	638
Other	2,935	3,734
Total noninterest expense	25,858	29,407
Income before income tax expense	17,997	16,489
Income tax expense	3,008	2,973
Net income	$ 14,989	$ 13,516
Earnings per common share - basic (in dollars per share)	$ 0.52	$ 0.51
Earnings per common share - diluted (in dollars per share)	0.52	0.51
Dividends paid on common stock (in dollars per share)	$ 0.25	$ 0.23

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 14,989	$ 13,516
Securities available for sale and transferred securities:
Change in net unrealized holding gains on available for sale securities during the period	4,885	27,744
Reclassification adjustment for amortization of unrealized losses on securities transferred to held to maturity	488	57
Reclassification adjustment for net gain on sale of available for sale securities, included in net income	(322)	(2,441)
Derivatives:
Change in net unrealized loss on effective cash flow hedge interest rate swap derivatives	(80)	(2,601)
Change in net unrealized gains on interest rate swap derivatives terminated during the period	273	0
Reclassification adjustment for net loss on interest rate swap derivatives, included in net income	379	357
Reclassification adjustment for amortization of unrealized gains on terminated interest rate swap derivatives	(9)	0
Pension plans:
Amortization of net actuarial loss, included in net periodic benefit cost	391	411
Amortization of prior service credit, included in net periodic benefit cost	(2)	(4)
Other comprehensive income, before tax	6,003	23,523
Income tax expense related to items of other comprehensive income	(2,101)	(8,233)
Other comprehensive income, net of tax	3,902	15,290
Comprehensive income	$ 18,891	$ 28,806

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)
Beginning Balance at Dec. 31, 2015	$ 444,062	$ 34,832	$ 424,078	$ 41,527	$ (37,692)	$ (18,683)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	13,516			13,516
Other comprehensive income	15,290					15,290
Issuance of common stock for dividend reinvestment plan (10,433 shares in 2017 and 12,030 shares in 2016)	314	15	299
Purchase of common stock (443,426 shares)	(10,199)				(10,199)
Stock compensation expense	355		355
Tax expense related to stock awards	(12)		(12)
Net issuance of common stock under employee stock plans (33,596 in 2017 and 4,912 in 2016)	24	6	33	(15)
Cash dividends paid on common stock ($0.25 per share in 2017 and $0.23 per share in 2016)	(5,774)			(5,774)
Ending Balance at Mar. 31, 2016	457,576	34,853	424,753	49,254	(47,891)	(3,393)
Beginning Balance at Dec. 31, 2016	518,274	39,320	535,240	30,098	(47,891)	(38,493)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	14,989			14,989
Other comprehensive income	3,902					3,902
Issuance of common stock for dividend reinvestment plan (10,433 shares in 2017 and 12,030 shares in 2016)	353	13	340
Stock compensation expense	494		494
Net issuance of common stock under employee stock plans (33,596 in 2017 and 4,912 in 2016)	597	42	579	(24)
Cash dividends paid on common stock ($0.25 per share in 2017 and $0.23 per share in 2016)	(7,143)			(7,143)
Ending Balance at Mar. 31, 2017	$ 531,466	$ 39,375	$ 536,653	$ 37,920	$ (47,891)	$ (34,591)

CONSOLIDATED STATEMENTS OF CHA7

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Stockholders' Equity [Abstract]
Stock Issued During Period, Shares, Dividend Reinvestment Plan	10,433	12,030
Dividends paid on common stock (in dollars per share)	$ 0.25	$ 0.23
Treasury Stock, Shares, Acquired		443,000
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	33,596	4,912

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
OPERATING ACTIVITIES:
Net income	$ 14,989,000	$ 13,516,000
Adjustments to reconcile net income to net cash provided by operations:
Depreciation and net amortization	2,417,000	2,169,000
Securities premium amortization (discount accretion), net	4,567,000	4,510,000
Loan (discount accretion) premium amortization, net	(290,000)	(799,000)
Provision for loan losses	1,098,000	2,316,000
Stock compensation expense	494,000	355,000
Deferred tax benefit	(19,000)	(812,000)
Net tax (expense) benefit related to stock awards	0	12,000
Net gain on sale of securities available for sale	(322,000)	(2,441,000)
Net gain on premises and equipment	0	(19,000)
Gross proceeds from sales of loans held for sale	22,521,000	17,944,000
Gross originations of loans held for sale	(20,183,000)	(19,104,000)
Net loss on other real estate owned	0	152,000
Net change in:
Interest receivable	6,910,000	6,152,000
Other assets	7,419,000	590,000
Interest payable	(1,523,000)	291,000
Other liabilities	(5,377,000)	1,243,000
Net cash provided by operating activities	32,701,000	26,075,000
Securities available for sale:
Purchases	(139,246,000)	(135,648,000)
Sales	99,653,000	251,976,000
Maturities, calls and principal repayments	29,770,000	47,407,000
Securities held to maturity:
Purchases	(1,521,000)	(18,922,000)
Maturities, calls and principal repayments	8,305,000	5,168,000
Proceeds from redemption of FHLB stock and other investments	81,000	3,644,000
Purchases of FHLB stock and other investments	(221,000)	(171,000)
Net loans originated	17,201,000	(11,420,000)
Purchases of premises and equipment	(1,287,000)	(1,648,000)
Proceeds from sales of premises and equipment	3,000	50,000
Proceeds from sales of other real estate owned	0	483,000
Proceeds from sales of repossessed assets	179,000	311,000
Net cash provided by investing activities	12,917,000	141,230,000
FINANCING ACTIVITIES:
Net change in deposits	140,978,000	164,249,000
Net increase in federal funds purchased and repurchase agreements	717,000	72,000
Proceeds from FHLB advances	725,000,000	2,916,882,000
Repayment of FHLB advances	(828,780,000)	(3,245,382,000)
Tax expense related to stock awards	0	(12,000)
Proceeds from stock option exercises	639,000	35,000
Cash paid to tax authority from stock option exercises	(42,000)	(11,000)
Purchase of common stock	0	10,199,000
Proceeds from the issuance of common stock for dividend reinvestment plan	353,000	314,000
Cash dividends paid	(7,143,000)	(5,774,000)
Net cash provided by (used in) financing activities	31,722,000	(179,826,000)
Net increase (decrease) in cash and cash equivalents	77,340,000	(12,521,000)
Cash and cash equivalents at beginning of period	169,654,000	80,975,000
Cash and cash equivalents at end of period	246,994,000	68,454,000
SUPPLEMENTAL DISCLOSURES FOR CASH FLOW INFORMATION:
Interest paid	11,131,000	6,104,000
Income taxes paid	0	0
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Loans transferred to other repossessed assets and real estate through foreclosure	184,000	465,000
Adjustment to pension liability	(389,000)	(407,000)
Unsettled trades to purchase securities	(10,465,000)	(23,920,000)
Unsettled trades to sell securities	57,385,000	15,039,000
Unsettled issuances of brokered CDs	$ 31,232,000	$ 0

Summary of Significant Accounti

Summary of Significant Accounting and Reporting Policies	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	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. The words “Southside” and “Southside Bancshares” refer to Southside Bancshares, Inc. The words “Southside Bank” and “the Bank” refer to Southside Bank. “Omni” refers to OmniAmerican Bancorp, Inc., a bank holding company acquired by Southside on December 17, 2014. The consolidated balance sheet as of March 31, 2017 , and the related consolidated statements of income, comprehensive income, changes in shareholders’ equity, cash flows and notes to the financial statements for the three- month periods ended March 31, 2017 and 2016 are unaudited; 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. All intercompany accounts and transactions are eliminated in consolidation. The preparation of these consolidated financial statements in conformity with U.S. generally accepted accounting principles (“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, 2016 . Accounting Changes and Reclassifications Certain prior period amounts have been reclassified to conform to current year presentation. We adopted ASU 2016-09 “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,” on January 1, 2017 which requires all income tax effects related to settlements of share-based payment awards be reported in earnings as an increase (or decrease) to income tax expense. Previously, income tax benefits at settlement of an award were reported as an increase (or decrease) to additional paid-in capital to the extent that those benefits were greater than (or less than) the income tax benefits recognized in earnings during the vesting period or exercise of the award. The requirement to report those income tax effects in earnings has been applied to settlements occurring on or after January 1, 2017, and the impact of applying that guidance reduced reported income tax expense by $126,000 , or less than $0.01 on our diluted earnings per common share. ASU 2016-09 also requires that all income tax-related cash flows resulting from share-based payments be reported as operating activities in the statement of cash flows. Previously, income tax benefits at settlement of an award were reported as a reduction to operating cash flows and an increase to financing cash flows to the extent that those benefits exceeded the income tax benefits reported in earnings during the vesting period or exercise of the award. We have elected to apply that change in cash flow on a prospective basis and therefore, prior periods have not been adjusted. ASU 2016-09 also requires the classification of employee taxes paid when an employer withholds shares for tax withholding purposes be classified as a financing activity in the statement of cash flow and be applied retrospectively. The requirement to report the employee taxes paid is reflected in prior period presentation in our consolidated statement of cash flows. In connection with the adoption of ASU 2016-09, we have also elected to recognize forfeitures as they occur. Terminated Derivative Financial Instruments 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 accumulated other comprehensive income will continue to be reclassified into earnings during the period or periods in which the hedged forecasted transaction affects earnings unless it is probable that the forecasted transaction will not occur by the end of the originally specified time period. If the forecasted transaction is deemed probable to not occur, the derivative gain or loss reported in accumulated other comprehensive income shall be reclassified into earnings immediately. During the first quarter of 2017, we terminated two interest rate swap contracts designated as cash flow hedges. At the time of termination, we determined that the underlying hedged forecasted transactions were still probable of occurring. The existing gain in accumulated other comprehensive income related to the terminated interest rate swap contracts will be reclassified into earnings through straight-line accretion in the same periods the hedged forecasted transaction affects earnings. Further information on our derivative instruments and hedging activities is included in “Note 8 - Derivative Financial Instruments and Hedging Activities.” For a description of our significant accounting and reporting policies, refer to “Note 1- Summary of Significant Accounting and Reporting Policies” in our consolidated financial statements in our Annual Report on Form 10-K for the year ended December 31, 2016 . Accounting Pronouncements In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” This update states that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update affects entities that enter into contracts with customers to transfer goods or services or enter into contracts for the transfer of nonfinancial assets, unless those contracts are within the scope of other standards. In August 2015, the FASB issued ASU 2015-14, “Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date,” which effectively delayed the adoption date by one year. We are required to adopt ASU 2014-09 in the first quarter of fiscal 2018. Early adoption is permitted. The guidance permits companies to either apply the requirements retrospectively to all prior periods presented, or apply the requirements in the year of adoption, through cumulative adjustment. Our revenue consists of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and noninterest income. We are currently evaluating the impact this guidance will have in relation to our noninterest income derived from contracts with our customers as it relates to deposit services, trust income, brokerage services, and merchant services (included in other noninterest income) which we have determined to be in the scope of ASU 2014-09. We anticipate our assessment for these areas to be completed during the second quarter of 2017 at which time we will select the transition method to be applied upon adoption. We are concurrently evaluating the impact and resources needed to fulfill the additional disclosures required by this guidance. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” ASU 2016-02 requires a lessee to recognize assets and liabilities for leases with lease terms of more than 12 months. Consistent with current GAAP, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance or operating lease. However, unlike current GAAP which requires only capital leases to be recognized on the balance sheet, the new ASU 2016-02 will require both finance (formerly known as “capital”) and operating leases to be recognized on the balance sheet. ASU 2016-02 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The guidance requires companies to apply the requirements in the year of adoption using a modified retrospective approach. We are currently evaluating the impact this guidance will have on our financial statements and we anticipate our assessment to be completed during the fiscal year 2018. In June 2016, the FASB issued ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” ASU 2016-13 introduces an approach based on expected losses to estimate credit losses on certain types of financial instruments. ASU 2016-13 also modifies the impairment model for available for sale debt securities and provides for a simplified accounting model for purchased financial assets with credit deterioration since their origination. ASU 2016-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The guidance requires companies to apply the requirements in the year of adoption through cumulative adjustment with some aspects of the update requiring a prospective transition approach. We are currently evaluating the potential impact of the pending adoption of ASU 2016-13 on our consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” ASU 2017-04 is intended to simplify goodwill impairment testing by eliminating the second step of the analysis which requires the calculation of the implied fair value of goodwill to measure a goodwill impairment charge. The update requires entities to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit’s fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. ASU 2017-04 is effective for annual and interim goodwill impairment tests performed in periods beginning after December 15, 2019. Early adoption is permitted for annual and interim goodwill impairment testing dates after January 1, 2017. The guidance requires companies to apply the requirements prospectively in the year of adoption. ASU 2017-04 is not expected to have a significant impact on our consolidated financial statements. In March 2017, the FASB issued ASU 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.” ASU 2017-07 requires employers to present the service cost component of net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Only the service cost component will be eligible for capitalization in assets. Employers are required to present the other components of the net periodic benefit cost separately from the line item that includes the service cost and outside of any subtotal of operating income, if one is presented. ASU 2017-07 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Early adoption is permitted as of the beginning of an annual period for which financial statements (interim or annual) have not been issued or made available for issuance. We did not early adopt. The guidance requires companies to apply the requirements retrospectively to all prior periods presented. We are currently evaluating the potential impact of the pending adoption of ASU 2017-07 on our consolidated financial statements. In March 2017, the FASB issued ASU 2017-08, “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.” Under current GAAP, premiums on callable debt securities are generally amortized over the contractual life of the security. ASU 2017-08 requires the premium on callable debt securities to be amortized to the earliest call date. If the debt security is not called at the earliest call date, the holder of the debt security would be required to reset the effective yield on the debt security based on the payment terms required by the debt security. ASU 2017-08 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The guidance requires companies to apply the requirements on a modified retrospective basis through a cumulative adjustment directly to retained earnings as of the beginning of the period of adoption. We are currently evaluating the potential impact of the pending adoption of ASU 2017-08 on our consolidated financial statements.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Earnings per share on a basic and diluted basis has been adjusted to give retroactive recognition to stock dividends and is calculated as follows (in thousands, except per share amounts): Three Months Ended 2017 2016 Basic and Diluted Earnings: Net income $ 14,989 $ 13,516 Basic weighted-average shares outstanding 28,569 26,449 Add: Stock awards 208 70 Diluted weighted-average shares outstanding 28,777 26,519 Basic Earnings Per Share: Net Income $ 0.52 $ 0.51 Diluted Earnings Per Share: Net Income $ 0.52 $ 0.51 For the three- month periods ended March 31, 2017 and 2016 , there were approximately 52,000 and 112,000 antidilutive shares, respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2017
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, 2017 Pension Plans Unrealized Gains (Losses) on Securities Unrealized Gains (Losses) on Derivatives Net Prior Net Gain (Loss) Total Beginning balance, net of tax $ (23,708 ) $ 4,595 $ (133 ) $ (19,247 ) $ (38,493 ) Other comprehensive income (loss): Other comprehensive income before reclassifications 4,885 193 — — 5,078 Reclassified from accumulated other comprehensive income 166 370 (2 ) 391 925 Income tax (expense) benefit (1,768 ) (197 ) 1 (137 ) (2,101 ) Net current-period other comprehensive income (loss), net of tax 3,283 366 (1 ) 254 3,902 Ending balance, net of tax $ (20,425 ) $ 4,961 $ (134 ) $ (18,993 ) $ (34,591 ) Three Months Ended March 31, 2016 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 $ (239 ) $ — $ (44 ) $ (18,400 ) $ (18,683 ) Other comprehensive income (loss): Other comprehensive income (loss) before reclassifications 27,744 (2,601 ) — — 25,143 Reclassified from accumulated other comprehensive income (2,384 ) 357 (4 ) 411 (1,620 ) Income tax (expense) benefit (8,876 ) 785 1 (143 ) (8,233 ) Net current-period other comprehensive income (loss), net of tax 16,484 (1,459 ) (3 ) 268 15,290 Ending balance, net of tax $ 16,245 $ (1,459 ) $ (47 ) $ (18,132 ) $ (3,393 ) The reclassifications out of accumulated other comprehensive income (loss) into net income are presented below (in thousands): Three Months Ended 2017 2016 Unrealized losses on securities transferred to held to maturity: Amortization of unrealized losses (1) $ (488 ) $ (57 ) Tax benefit 171 20 Net of tax $ (317 ) $ (37 ) Unrealized gains and losses on available for sale securities: Realized net gain on sale of securities (2) $ 322 $ 2,441 Tax expense (113 ) (854 ) Net of tax $ 209 $ 1,587 Derivatives: Realized net loss on interest rate swap derivatives (3) $ (379 ) $ (357 ) Tax benefit 133 125 Net of tax $ (246 ) $ (232 ) Amortization of unrealized gains on terminated interest rate swap derivatives (3) $ 9 $ — Tax expense (3 ) — Net of tax $ 6 $ — Amortization of pension plan: Net actuarial loss (4) $ (391 ) $ (411 ) Prior service credit (4) 2 4 Total before tax (389 ) (407 ) Tax benefit 136 142 Net of tax (253 ) (265 ) Total reclassifications for the period, net of tax $ (601 ) $ 1,053 (1) Included in interest income on the consolidated statements of income. (2) Listed as net gain on sale of securities available for sale on the consolidated statements of income. (3) Included in interest expense for long-term obligations on the consolidated statements of income. (4) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (income) presented in “Note 7 - Employee Benefit Plans.”

Securities

Securities	3 Months Ended
	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Securities	Securities The amortized cost, gross unrealized gains and losses, carrying value, and estimated fair value of investment and mortgage-backed securities as of March 31, 2017 and December 31, 2016 are reflected in the tables below (in thousands): March 31, 2017 Recognized in OCI Not recognized in OCI Amortized Gross Unrealized Gross Unrealized Carrying Gross Gross Unrealized Estimated AVAILABLE FOR SALE Cost Gains Losses Value Gains Losses Fair Value Investment Securities: U.S. Treasury $ 62,015 $ — $ 2,801 $ 59,214 $ — $ — $ 59,214 State and Political Subdivisions 328,395 3,227 10,775 320,847 — — 320,847 Other Stocks and Bonds 6,574 84 — 6,658 — — 6,658 Other Equity Securities 6,036 — 116 5,920 — — 5,920 Mortgage-backed Securities: (1) Residential 685,934 6,621 7,893 684,662 — — 684,662 Commercial 368,330 896 2,484 366,742 — — 366,742 Total $ 1,457,284 $ 10,828 $ 24,069 $ 1,444,043 $ — $ — $ 1,444,043 HELD TO MATURITY Investment Securities: State and Political Subdivisions $ 430,350 $ 3,631 $ 12,848 $ 421,133 $ 8,902 $ 2,747 $ 427,288 Mortgage-backed Securities: (1) Residential 137,693 — 5,478 132,215 1,536 370 133,381 Commercial 379,931 1,025 4,511 376,445 4,952 1,657 379,740 Total $ 947,974 $ 4,656 $ 22,837 $ 929,793 $ 15,390 $ 4,774 $ 940,409 December 31, 2016 Recognized in OCI Not recognized in OCI Amortized Gross Unrealized Gross Unrealized Carrying Gross Gross Unrealized Estimated AVAILABLE FOR SALE Cost Gains Losses Value Gains Losses Fair Value Investment Securities: U.S. Treasury $ 74,016 $ — $ 3,947 $ 70,069 $ — $ — $ 70,069 State and Political Subdivisions 394,050 3,217 12,070 385,197 — — 385,197 Other Stocks and Bonds 6,587 64 — 6,651 — — 6,651 Other Equity Securities 6,039 — 119 5,920 — — 5,920 Mortgage-backed Securities: (1) Residential 630,603 6,434 9,529 627,508 — — 627,508 Commercial 386,109 1,201 3,055 384,255 — — 384,255 Total $ 1,497,404 $ 10,916 $ 28,720 $ 1,479,600 $ — $ — $ 1,479,600 HELD TO MATURITY Investment Securities: State and Political Subdivisions $ 435,080 $ 3,987 $ 13,257 $ 425,810 $ 7,595 $ 3,493 $ 429,912 Mortgage-backed Securities: (1) Residential 142,060 — 5,748 136,312 1,534 950 136,896 Commercial 379,016 1,067 4,718 375,365 4,372 2,263 377,474 Total $ 956,156 $ 5,054 $ 23,723 $ 937,487 $ 13,501 $ 6,706 $ 944,282 (1) All mortgage-backed securities issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. From time to time, we may transfer securities from available for sale (“AFS”) to held to maturity (“HTM”) due to overall balance sheet strategies. During 2016, the Company transferred securities with a fair value of $157.1 million from AFS to HTM. The unrealized loss on the securities transferred from AFS to HTM was $10.2 million ( $6.7 million , net of tax) at the date of transfer based on the fair value of the securities on the transfer date. Our management has the current intent and ability to hold the transferred securities until maturity. Any net unrealized gain or loss on the transferred securities included in accumulated other comprehensive income at the time of transfer will be amortized over the remaining life of the underlying security as an adjustment of the yield on those securities. AFS securities transferred with losses included in accumulated other comprehensive income continue to be included in management’s assessment for other-than-temporary impairment for each individual security. There were no securities transferred from AFS to HTM during the three months ended March 31, 2017 . The following tables represent the estimated fair value and unrealized loss on securities as of March 31, 2017 and December 31, 2016 (in thousands): As of March 31, 2017 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 $ 59,214 $ 2,801 $ — $ — $ 59,214 $ 2,801 State and Political Subdivisions 209,637 10,774 886 1 210,523 10,775 Other Equity Securities 5,920 116 — — 5,920 116 Mortgage-backed Securities: Residential 361,710 7,887 2,344 6 364,054 7,893 Commercial 248,331 2,484 — — 248,331 2,484 Total $ 884,812 $ 24,062 $ 3,230 $ 7 $ 888,042 $ 24,069 HELD TO MATURITY Investment Securities: State and Political Subdivisions $ 99,422 $ 1,372 $ 25,976 $ 1,375 $ 125,398 $ 2,747 Mortgage-backed Securities: Residential 55,917 370 — — 55,917 370 Commercial 172,138 1,657 — — 172,138 1,657 Total $ 327,477 $ 3,399 $ 25,976 $ 1,375 $ 353,453 $ 4,774 As of December 31, 2016 Less Than 12 Months More Than 12 Months Total Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized AVAILABLE FOR SALE Investment Securities: U.S. Treasury $ 70,069 $ 3,947 $ — $ — $ 70,069 $ 3,947 State and Political Subdivisions 264,485 12,069 887 1 265,372 12,070 Other Equity Securities 5,920 119 — — 5,920 119 Mortgage-backed Securities: Residential 369,903 9,491 6,199 38 376,102 9,529 Commercial 245,422 3,055 — — 245,422 3,055 Total $ 955,799 $ 28,681 $ 7,086 $ 39 $ 962,885 $ 28,720 HELD TO MATURITY Investment Securities: State and Political Subdivisions $ 179,939 $ 2,190 $ 29,427 $ 1,303 $ 209,366 $ 3,493 Mortgage-backed Securities: Residential 107,024 950 — — 107,024 950 Commercial 186,854 2,263 — — 186,854 2,263 Total $ 473,817 $ 5,403 $ 29,427 $ 1,303 $ 503,244 $ 6,706 We review those securities in an unrealized loss position for significant differences between fair value and the cost basis to evaluate if a classification of other-than-temporary impairment is warranted. In estimating other-than-temporary impairment losses, management considers, among other things, the length of time and the extent to which the fair value has been less than cost and the financial condition and near-term prospects of the issuer. We consider an other-than-temporary impairment to have occurred when there is an adverse change in expected cash flows. When it is determined that a decline in fair value of HTM or AFS securities is other-than-temporary, the carrying value of the security is reduced to its estimated fair value, with a corresponding charge to earnings for the credit portion and the noncredit portion to other comprehensive income. Based upon the length of time and the extent to which fair value is less than cost, we believe that none of the securities with an unrealized loss have other-than-temporary impairment at March 31, 2017 . The majority of the securities in an unrealized loss position are highly rated municipal securities and U.S. Agency mortgage-backed securities (“MBS”) where the unrealized loss is a direct result of the change in interest rates and spreads. For those securities in an unrealized loss position, we do not currently intend to sell the securities and it is not more likely than not that we will be required to sell the securities before the anticipated recovery of their amortized cost basis. To the best of management’s knowledge and based on our consideration of the qualitative factors associated with each security, there were no securities in our investment and MBS portfolio with an other-than-temporary impairment at March 31, 2017 . Our equity securities consist of investments that are deemed to be qualified under the Community Reinvestment Act (CRA) of 1977 and invest primarily in securities issued by Fannie Mae, Freddie Mac, and Ginnie Mae. We evaluated the near-term prospects of our other equity securities in relation to the severity and duration of the current unrealized loss position. Based upon that evaluation, management does not consider the other equity securities to be other-than-temporarily impaired at March 31, 2017 . Interest income recognized on securities for the periods presented (in thousands): Three Months Ended 2017 2016 U.S. Treasury $ 315 $ 127 State and Political Subdivisions 6,554 5,355 Other Stocks and Bonds 34 58 Other Equity Securities 28 29 Mortgage-backed Securities 10,045 9,391 Total interest income on securities $ 16,976 $ 14,960 Of the approximately $322,000 in net securities gains from the AFS portfolio for the three months ended March 31, 2017 , there were $1.7 million in realized gain positions and $1.4 million in realized loss positions. Of the $2.4 million in net securities gains from the AFS portfolio for the three months ended March 31, 2016 , there were $2.6 million in realized gain positions and $202,000 in realized loss positions. There were no sales from the HTM portfolio during the three months ended March 31, 2017 or 2016 . We calculate realized gains and losses on sales of securities under the specific identification method. The amortized cost, carrying value and estimated fair value of securities at March 31, 2017 , are presented below by contractual maturity (in thousands). Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations. MBS are presented in total by category due to the fact that MBS typically are issued with stated principal amounts, and the securities 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. March 31, 2017 Amortized Cost Fair Value AVAILABLE FOR SALE Investment Securities: Due in one year or less $ 6,694 $ 6,851 Due after one year through five years 23,638 24,655 Due after five years through ten years 96,416 93,961 Due after ten years 270,236 261,252 396,984 386,719 Mortgage-backed Securities and Other Equity Securities: 1,060,300 1,057,324 Total $ 1,457,284 $ 1,444,043 March 31, 2017 Carrying Value Fair Value HELD TO MATURITY Investment Securities: Due in one year or less $ 10,119 $ 10,181 Due after one year through five years 39,539 39,935 Due after five years through ten years 101,274 101,898 Due after ten years 270,201 275,274 421,133 427,288 Mortgage-backed Securities: 508,660 513,121 Total $ 929,793 $ 940,409 Investment securities and MBS with carrying values of $1.29 billion and $1.50 billion were pledged as of March 31, 2017 and December 31, 2016 , respectively, to collateralize Federal Home Loan Bank of Dallas (“FHLB”) advances, repurchase agreements, and public funds or for other purposes as required by law. Securities with limited marketability, such as FHLB stock and other investments, are carried at cost, which approximates fair value and are assessed for other-than-temporary impairment. These securities have no maturity date.

Loans and Allowance for Probabl

Loans and Allowance for Probable Loan Losses	3 Months Ended
	Mar. 31, 2017
Receivables [Abstract]
Loans and Allowance for Probable Loan Losses	Loans and Allowance for Probable Loan Losses Loans in the accompanying consolidated balance sheets are classified as follows (in thousands): March 31, 2017 December 31, 2016 Real Estate Loans: Construction $ 362,367 $ 380,175 1-4 Family Residential 622,881 637,239 Commercial 974,307 945,978 Commercial Loans 176,908 177,265 Municipal Loans 297,417 298,583 Loans to Individuals 105,038 117,297 Total Loans (1) 2,538,918 2,556,537 Less: Allowance for Loan Losses (2) 18,485 17,911 Net Loans $ 2,520,433 $ 2,538,626 (1) Includes approximately $324.9 million and $372.4 million of loans acquired with the Omni acquisition as of March 31, 2017 and December 31, 2016 , respectively. (2) The allowance for loan loss recorded on purchase credit impaired (“PCI”) loans totaled $3,000 as of March 31, 2017 and December 31, 2016 . Real Estate Construction Loans Our construction loans are collateralized by property located primarily in or near the market areas we serve. Several 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 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. Real Estate 1-4 Family Residential 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 to 30 years. These loans are typically fully amortizing with monthly payments sufficient to repay the total amount of the loan. Our 1-4 family residential loans are made at both fixed and adjustable interest rates. 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, 2017 consist of $902.9 million of owner and non-owner occupied real estate, $67.7 million of loans secured by multi-family properties and $3.7 million of loans secured by farmland. Commercial real estate loans primarily include loans collateralized by retail, commercial office buildings, multi-family, 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. Management does not consider there to be a concentration of risk in any one industry type. 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 have a specific lending department that makes loans to municipalities and school districts primarily throughout the state of Texas. Municipal loans outside the state of Texas have been limited to adjoining states. 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. 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 should assist in limiting our exposure. Allowance for Loan Losses The allowance for loan losses is based on the most current review of the loan portfolio and is a result of multiple processes. First, we utilize historical net charge-off data to establish general reserve amounts for each class of loans. The historical charge-off figure is further adjusted through qualitative factors that include general trends in past dues, nonaccruals and classified loans to more effectively and promptly react to both positive and negative movements not reflected in the historical data. Second, our lenders have the primary responsibility for identifying problem loans based on customer financial stress and underlying collateral. These recommendations are reviewed by senior loan administration, the special assets department, and the loan review department on a monthly basis. Third, the loan review department independently reviews the portfolio on an annual basis. The loan review department follows a board-approved annual loan review scope. The loan review scope encompasses a number of considerations including the size of the loan, the type of credit extended, the seasoning of the loan and the performance of the loan. The loan review scope, as it relates to size, focuses more on larger dollar loan relationships, typically aggregate debt of $500,000 or greater. The loan review officer also reviews specific reserves compared to general reserves to determine trends in comparative reserves as well as losses not reserved for prior to charge-off to determine the effectiveness of the specific reserve process. At each review, a subjective analysis methodology is used to grade the respective loan. Categories of grading vary in severity from loans that do not appear to have a significant probability of loss at the time of review to loans that indicate a probability that the entire balance of the loan will be uncollectible. If at the time of review we determine it is probable that we will not collect the principal and interest cash flows contractually due on the loan, estimates of future expected cash flows or appraisals of the collateral securing the debt are used to determine the necessary allowances. The internal loan review department maintains a list of all loans or loan relationships that are graded as having more than the normal degree of risk associated with them. In addition, a list of specifically reserved loans or loan relationships of $150,000 or more is updated on a quarterly basis in order to properly determine necessary allowances and keep management informed on the status of attempts to correct the deficiencies noted with respect to the loan. We calculate historical loss ratios for pools of loans with similar characteristics based on the proportion of actual charge-offs experienced, consistent with the characteristics of remaining loans, to the total population of loans in the pool. The historical gross loss ratios are updated based on actual charge-off experience quarterly and adjusted for qualitative factors. All loans are subject to individual analysis if determined to be impaired with the exception of consumer loans and loans secured by 1-4 family residential loans. Industry and our own experience indicates that a portion of our loans will become delinquent and a portion of the loans will require partial or full charge-off. Regardless of the underwriting criteria utilized, losses may occur as a result of various factors beyond our control, including, among other things, changes in market conditions affecting the value of properties used as collateral for loans and problems affecting the credit worthiness of the borrower and the ability of the borrower to make payments on the loan. Our determination of the appropriateness of the allowance for loan losses is based on various considerations, including an analysis of the risk characteristics of various classifications of loans, previous loan loss experience, specific loans which would have loan loss potential, delinquency trends, estimated fair value of the underlying collateral, current economic conditions, and geographic and industry loan concentration. 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 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 asset 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 asset or in our credit position at some future date. Special Mention assets 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. All accruing loans are reserved for as a group of similar type credits and included in the general portion of the allowance for loan losses. Loans to individuals and 1-4 family residential loans, including loans not accruing, are collectively evaluated and included in the general portion of the allowance for loan losses. All loans considered troubled debt restructurings (“TDR”) are evaluated individually for further impairment. The general portion of the loan loss allowance is reflective of historical charge-off levels for similar loans adjusted for changes in current conditions and other relevant factors. These factors are likely to cause estimated losses to differ from historical loss experience and include: • Changes in lending policies or procedures, including underwriting, collection, charge-off, and recovery procedures; • Changes in local, regional and national economic and business conditions, including entry into new markets; • Changes in the volume or type of credit extended; • Changes in the experience, ability, and depth of lending management; • Changes in the volume and severity of past due, nonaccrual, restructured, or classified loans; • Changes in charge-off trends; • Changes in loan review or Board oversight; • Changes in the level of concentrations of credit; and • Changes in external factors, such as competition and legal and regulatory requirements. These factors are also considered for the purchased Omni loan portfolio specifically in regards to changes in credit quality, past due, nonaccrual and charge-off trends. 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, 2017 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Balance at beginning of period $ 4,147 $ 2,665 $ 7,204 $ 2,263 $ 750 $ 882 $ 17,911 Provision (reversal) for loan losses (1) (722 ) (62 ) 1,577 (112 ) (4 ) 421 1,098 Loans charged off (18 ) (287 ) — (3 ) — (746 ) (1,054 ) Recoveries of loans charged off — 1 6 111 — 412 530 Balance at end of period $ 3,407 $ 2,317 $ 8,787 $ 2,259 $ 746 $ 969 $ 18,485 Three Months Ended March 31, 2016 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Balance at beginning of period $ 4,350 $ 2,595 $ 4,577 $ 6,596 $ 725 $ 893 $ 19,736 Provision (reversal) for loan losses (1) (42 ) (551 ) (116 ) 2,620 (5 ) 410 2,316 Loans charged off — (19 ) — (273 ) — (848 ) (1,140 ) Recoveries of loans charged off 269 130 6 21 — 461 887 Balance at end of period $ 4,577 $ 2,155 $ 4,467 $ 8,964 $ 720 $ 916 $ 21,799 (1) Of the $1.1 million and $2.3 million recorded in provision for loan losses for the three months ended March 31, 2017 and March 31, 2016 , none related to provision expense on PCI loans as of March 31, 2017 and $296,000 related to provision expense on PCI loans as of March 31, 2016 . The following tables present the balance in the allowance for loan losses by portfolio segment based on impairment method (in thousands): As of March 31, 2017 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Ending balance – individually evaluated for impairment (1) $ 10 $ 13 $ 15 $ 982 $ 11 $ 91 $ 1,122 Ending balance – collectively evaluated for impairment 3,397 2,304 8,772 1,277 735 878 17,363 Balance at end of period $ 3,407 $ 2,317 $ 8,787 $ 2,259 $ 746 $ 969 $ 18,485 As of December 31, 2016 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Ending balance – individually evaluated for impairment (1) $ 13 $ 16 $ 17 $ 923 $ 11 $ 106 $ 1,086 Ending balance – collectively evaluated for impairment 4,134 2,649 7,187 1,340 739 776 16,825 Balance at end of period $ 4,147 $ 2,665 $ 7,204 $ 2,263 $ 750 $ 882 $ 17,911 (1) There was approximately $3,000 of allowance for loan losses associated with PCI loans as of March 31, 2017 and December 31, 2016 . The following tables present the recorded investment in loans by portfolio segment based on impairment method (in thousands): March 31, 2017 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Loans individually evaluated for impairment $ 430 $ 1,672 $ 1,081 $ 5,529 $ 571 $ 225 $ 9,508 Loans collectively evaluated for impairment 361,784 615,628 971,593 170,090 296,846 104,712 2,520,653 Purchased credit impaired loans 153 5,581 1,633 1,289 — 101 8,757 Total ending loan balance $ 362,367 $ 622,881 $ 974,307 $ 176,908 $ 297,417 $ 105,038 $ 2,538,918 December 31, 2016 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Loans individually evaluated for impairment $ 480 $ 1,693 $ 1,184 $ 5,840 $ 571 $ 241 $ 10,009 Loans collectively evaluated for impairment 379,526 629,893 942,818 170,159 298,012 116,923 2,537,331 Purchased credit impaired loans 169 5,653 1,976 1,266 — 133 9,197 Total ending loan balance $ 380,175 $ 637,239 $ 945,978 $ 177,265 $ 298,583 $ 117,297 $ 2,556,537 The following tables set forth credit quality indicators by class of loans for the periods presented (in thousands): March 31, 2017 Pass Pass Watch (1) Special Mention (1) Substandard (1) Doubtful (1) Total Real Estate Loans: Construction $ 358,837 $ 33 $ 159 $ 3,320 $ 18 $ 362,367 1-4 Family Residential 618,810 14 — 3,626 431 622,881 Commercial 922,584 3,258 8,657 39,808 — 974,307 Commercial Loans 162,780 1,167 4,372 8,544 45 176,908 Municipal Loans 295,896 — 950 571 — 297,417 Loans to Individuals 103,874 — 27 650 487 105,038 Total $ 2,462,781 $ 4,472 $ 14,165 $ 56,519 $ 981 $ 2,538,918 December 31, 2016 Pass Pass Watch (1) Special Mention (1) Substandard (1) Doubtful (1) Total Real Estate Loans: Construction $ 374,443 $ 34 $ 571 $ 5,108 $ 19 $ 380,175 1-4 Family Residential 632,937 68 — 3,380 854 637,239 Commercial 885,049 17,739 10,587 32,603 — 945,978 Commercial Loans 158,943 1,187 8,086 9,012 37 177,265 Municipal Loans 297,014 — 998 571 — 298,583 Loans to Individuals 115,952 — 9 629 707 117,297 Total $ 2,464,338 $ 19,028 $ 20,251 $ 51,303 $ 1,617 $ 2,556,537 (1) Includes PCI loans comprised of $5,000 pass watch, $507,000 special mention, $1.1 million substandard and $28,000 doubtful as of March 31, 2017 . Includes PCI loans comprised of $5,000 pass watch, $511,000 special mention, $1.5 million substandard and $28,000 doubtful as of December 31, 2016 . Nonperforming Assets and Past Due Loans Nonaccrual loans are loans 90 days or more delinquent and collection in full of both the principal and interest is not expected. Additionally, some loans that are not delinquent may be placed on nonaccrual status due to doubts about full collection of principal or interest. When a loan is categorized as nonaccrual, the accrual of interest is discontinued and any accrued balance is reversed for financial statement purposes. Payments received on nonaccrual loans are applied to the outstanding principal balance. Payments of contractual interest are recognized as income only to the extent that full recovery of the principal balance of the loan is reasonably certain. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured. Other factors, such as the value of collateral securing the loan and the financial condition of the borrower, are considered in judgments as to potential loan loss. Nonaccrual loans and accruing loans past due more than 90 days include both smaller balance homogeneous loans that are collectively evaluated for impairment and individually classified impaired loans. PCI loans are recorded at fair value at acquisition date. Although the PCI loans may be contractually delinquent, we do not classify these loans as past due or nonperforming as the loans were written down to fair value at the acquisition date and the accretable yield is recognized in interest income over the remaining life of the loan. However, subsequent to acquisition, we re-assess PCI loans for additional impairment and record additional impairment in the event we conclude it is probable that we will be unable to collect all cash flows originally expected to be collected at acquisition plus any additional cash flows expected to be collected due to changes in estimates after acquisition. All such PCI loans for which we recognize subsequent impairment are reported as impaired loans in the financial statements. The following table sets forth nonperforming assets for the periods presented (in thousands): At At Nonaccrual loans (1) $ 7,261 $ 8,280 Accruing loans past due more than 90 days (1) 1 6 Restructured loans (2) 6,424 6,431 Other real estate owned 367 339 Repossessed assets 26 49 Total Nonperforming Assets $ 14,079 $ 15,105 (1) Excludes PCI loans measured at fair value at acquisition. (2) Includes $3.0 million and $3.1 million in PCI loans restructured as of March 31, 2017 and December 31, 2016 , respectively. Foreclosed assets include other real estate owned 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. As of March 31, 2017 , there were no loans secured by 1-4 family residential properties for which formal foreclosure proceedings were in process. As of December 31, 2016 , there were $28,000 in loans secured by 1-4 family residential properties for which formal foreclosure proceedings were in process. The following table sets forth the recorded investment in nonaccrual loans by class of loans for the periods presented (in thousands). The table ex cludes PCI loans measured at fair value at acquisition : Nonaccrual Loans March 31, 2017 December 31, 2016 Real Estate Loans: Construction $ 55 $ 105 1-4 Family Residential 673 1,067 Commercial 723 808 Commercial Loans 5,127 5,477 Loans to Individuals 683 823 Total $ 7,261 $ 8,280 Loans are considered impaired if, based on current information and events, it is probable we will be unable to collect the scheduled payments of principal and interest when due according to the contractual terms of the loan agreement. Impairment is evaluated in total for smaller-balance loans of a similar nature and on an individual loan basis for other loans. The measurement of loss on impaired loans is generally based on the fair value of the collateral less selling costs if repayment is expected solely from the collateral or the present value of the expected future cash flows discounted at the historical effective interest rate stipulated in the loan agreement. In measuring the fair value of the collateral, in addition to relying on third party appraisals, we use assumptions, such as discount rates, and methodologies, such as comparison to the recent selling price of similar assets, consistent with those that would be utilized by unrelated third parties performing a valuation. Loans that are evaluated and determined not to meet the definition of an impaired loan are reserved for at the general reserve rate for its appropriate class. At the time a loss is probable in the collection of contractual amounts, specific reserves are allocated. Loans are charged off to the liquidation value of the collateral net of liquidation costs, if any, when deemed uncollectible or as soon as collection by liquidation is evident. The following tables set forth impaired loans by class of loans for the periods presented (in thousands). Impaired loans include restructured and nonaccrual loans for which the allowance was measured in accordance with section 310-10 of ASC Topic 310, “Receivables.” There were no impaired loans recorded without an allowance as of March 31, 2017 or December 31, 2016 . March 31, 2017 Unpaid Contractual Principal Balance Recorded Investment Related Allowance for Loan Losses Real Estate Loans: Construction $ 437 $ 430 $ 10 1-4 Family Residential 4,429 4,221 13 Commercial 1,530 1,465 15 Commercial Loans 5,798 5,638 982 Municipal Loans 571 571 11 Loans to Individuals 256 225 91 Total (1) $ 13,021 $ 12,550 $ 1,122 December 31, 2016 Unpaid Contractual Principal Balance Recorded Investment Related Allowance for Loan Losses Real Estate Loans: Construction $ 486 $ 480 $ 13 1-4 Family Residential 4,487 4,264 16 Commercial 1,631 1,574 17 Commercial Loans 6,108 5,941 923 Municipal Loans 571 571 11 Loans to Individuals 277 241 106 Total (1) $ 13,560 $ 13,071 $ 1,086 (1) Includes $3.0 million and $3.1 million of PCI loans that experienced deterioration in credit quality subsequent to the acquisition date as of March 31, 2017 and December 31, 2016 , respectively. The following tables present the aging of the recorded investment in past due loans by class of loans (in thousands): March 31, 2017 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days Past Due Total Past Due Current (1) Total Real Estate Loans: Construction $ 2,423 $ — $ 22 $ 2,445 $ 359,922 $ 362,367 1-4 Family Residential 5,330 81 329 5,740 617,141 622,881 Commercial 1,179 151 81 1,411 972,896 974,307 Commercial Loans 2,020 686 2,707 5,413 171,495 176,908 Municipal Loans 663 — — 663 296,754 297,417 Loans to Individuals 850 108 267 1,225 103,813 105,038 Total $ 12,465 $ 1,026 $ 3,406 $ 16,897 $ 2,522,021 $ 2,538,918 December 31, 2016 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days Past Due Total Past Due Current (1) Total Real Estate Loans: Construction $ 917 $ 64 $ 86 $ 1,067 $ 379,108 $ 380,175 1-4 Family Residential 6,225 755 600 7,580 629,659 637,239 Commercial 70 154 154 378 945,600 945,978 Commercial Loans 783 300 3,459 4,542 172,723 177,265 Municipal Loans 113 — — 113 298,470 298,583 Loans to Individuals 1,550 320 185 2,055 115,242 117,297 Total $ 9,658 $ 1,593 $ 4,484 $ 15,735 $ 2,540,802 $ 2,556,537 (1) Includes PCI loans measured at fair value at acquisition. The following table sets forth average recorded investment and interest income recognized on impaired loans by class of loans for the periods presented (in thousands). The table excludes PCI loans measured at fair value at acquisition that have not experienced further deterioration in credit quality subsequent to the acquisition date : Three Months Ended March 31, 2017 March 31, 2016 Average Recorded Investment Interest Income Recognized Average Recorded Interest Income Recognized Real Estate Loans: Construction $ 467 $ 4 $ 454 $ 6 1-4 Family Residential 4,262 57 1,865 14 Commercial 1,522 19 5,488 21 Commercial Loans 5,787 19 21,675 167 Municipal Loans 571 8 637 9 Loans to Individuals 265 2 247 2 Total $ 12,874 $ 109 $ 30,366 $ 219 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. The following tables set forth the recorded balance of loans considered to be TDRs that were restructured and the type of concession during the periods presented (dollars in thousands): Three Months Ended March 31, 2017 Extend Amortization Period Interest Rate Reductions Combination Total Modifications Number of Loans Commercial Loans $ 47 $ — $ — $ 47 1 Loans to Individuals 5 — 12 17 2 Total $ 52 $ — $ 12 $ 64 3 Three Months Ended March 31, 2016 Extend Amortization Period Interest Rate Reductions Combination Total Modifications Number of Loans Real Estate Loans: Construction $ 554 $ — $ — $ 554 1 Commercial 2,118 — — 2,118 1 Commercial Loans 1,176 — — 1,176 4 Total $ 3,848 $ — $ — $ 3,848 6 The majority of loans restructured as TDRs during the three months ended March 31, 2017 and 2016 were modified with maturity extensions. 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, 2017 and 2016 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 loan 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, 2017 , the amount of TDRs in default was not significant. For the three months ended March 31, 2016 , there were $1.4 million of TDRs in default. Payment defaults for TDRs did not significantly impact the determination of the allowance for loan loss in either period presented. At March 31, 2017 and 2016 , there were no commitments to lend additional funds to borrowers whose terms had been modified in TDRs. Purchased Credit Impaired Loans The following table presents the outstanding principal balance and carrying value for PCI loans for the periods presented (in thousands): March 31, 2017 December 31, 2016 Outstanding principal balance $ 9,924 $ 10,612 Carrying amount $ 8,757 $ 9,197 The following table presents the changes in the accretable yield during the periods for PCI loans (in thousands): Three Months Ended 2017 2016 Balance at beginning of period $ 2,480 $ 2,493 Reclassifications (to) from nonaccretable discount 1,819 443 Accretion (296 ) (594 ) Balance at end of period $ 4,003 $ 2,342

Long-term Obligations

Long-term Obligations	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Long-term Obligations	Long-term Obligations Long-term obligations are summarized as follows (in thousands): March 31, December 31, Parent Company Subordinated notes: (1) 5.50% Subordinated Notes Due 2026, net of unamortized debt issuance costs (2) $ 98,133 $ 98,100 Total Subordinated notes 98,133 98,100 Long-term debt: (3) Southside Statutory Trust III Due 2033, net of unamortized debt issuance costs (4) 20,545 20,544 Southside Statutory Trust IV Due 2037 (5) 23,196 23,196 Southside Statutory Trust V Due 2037 (6) 12,887 12,887 Magnolia Trust Company I Due 2035 (7) 3,609 3,609 Total Long-term debt 60,237 60,236 Total Parent Company 158,370 158,336 Subsidiaries FHLB advances (8) 252,940 443,128 Total Subsidiaries 252,940 443,128 Total Long-term obligations $ 411,310 $ 601,464 (1) This long-term 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 carries a fixed rate of 5.50% through September 29, 2021 and thereafter, adjusts quarterly at a rate equal to three-month LIBOR plus 429.7 basis points . (3) This long-term debt consists of trust preferred securities that qualify under the risk-based capital guidelines as Tier 1 capital, subject to certain limitations. (4) This debt carries an adjustable rate of 4.08678% through June 29, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 294 basis points . (5) This debt carries an adjustable rate of 2.339% through April 29, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 130 basis points . (6) This debt carries an adjustable rate of 3.38122% through June 14, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 225 basis points . (7) This debt carries an adjustable rate of 2.85344% through May 22, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 180 basis points . (8) At March 31, 2017 , the weighted average cost of these advances was 1.5% . Long-term FHLB advances have maturities ranging from April 2018 through July 2028 . On September 19, 2016 , the Company issued $100.0 million 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. The unamortized discount and debt issuance costs deducted from the subordinated notes issued totaled approximately $1.9 million at both March 31, 2017 and December 31, 2016 . The unamortized debt issuance costs reflected in the carrying amount of the Southside Statutory Trust III junior subordinated debentures totaled $74,000 at March 31, 2017 and $75,000 at December 31, 2016 . During the last sixteen months, the Company entered into various variable rate advances with the FHLB . These advances totaled $240.0 million at March 31, 2017 and $250.0 million at December 31, 2016 , of which $60.0 million and $230.0 million were considered long-term at March 31, 2017 and December 31, 2016 , respectively. Two of the variable rate advances have interest rates of three-month LIBOR minus 25 basis points. The remaining advances have interest rates ranging from one-month LIBOR plus 0.17% to one-month LIBOR plus 0.278% . In connection with obtaining these advances, the Company entered into various interest rate swap contracts that are treated as cash flow hedges under ASC Topic 815, “Derivatives and Hedging” that effectively converted the variable rate advances to fixed interest rates ranging from 0.932% to 2.345% and original terms ranging from five years to ten years. The cash flows from the swaps are expected to be effective in hedging the variability in future cash flows attributable to fluctuations in the one-month and three-month LIBOR interest rates. During the first quarter of 2017 , we terminated two interest rate swap contracts designated as cash flow hedges having a total notional value of $40.0 million . At the time of termination, we determined that the underlying hedged forecasted transactions were still probable of occurring. Refer to “Note 8 - 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.

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2017
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Employee Benefit Plans	Employee Benefit Plans The components of net periodic benefit cost (income) are as follows (in thousands): Three Months Ended March 31, Defined Benefit Defined Benefit Pension Plan Acquired Restoration 2017 2016 2017 2016 2017 2016 Service cost $ 358 $ 368 $ — $ — $ 51 $ 47 Interest cost 912 917 45 53 132 135 Expected return on assets (1,512 ) (1,354 ) (54 ) (67 ) — — Net loss amortization 344 358 — — 47 53 Prior service (credit) cost amortization (4 ) (6 ) — — 2 2 Special and contractual termination benefits — 1,520 — — — — Net periodic benefit cost (income) $ 98 $ 1,803 $ (9 ) $ (14 ) $ 232 $ 237

Derivative Financial Instrument

Derivative Financial Instruments and Hedging Activities	3 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure	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, or as cash flow hedges of forecasted transactions. Derivative instruments designated as cash flow hedges are recorded in accumulated other comprehensive income to the extent that they are 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. From time to time, we enter into certain interest rate swap contracts on specific variable-rate advance agreements with the FHLB. 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 $240.0 million of variable-rate advance agreements with the FHLB. The cash flows from the swap 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 accumulated other comprehensive income will continue to be reclassified into earnings during the period or periods in which the hedged forecasted transaction affects earnings unless it is probable that the forecasted transaction will not occur by the end of the originally specified time period. If the forecasted transaction is deemed probable to not occur, the derivative gain or loss reported in accumulated other comprehensive income shall be reclassified into earnings immediately. During the first quarter of 2017, we terminated two interest rate swap contracts designated as cash flow hedges. At the time of termination, we determined that the underlying hedged forecasted transactions were still probable of occurring. The existing gain in accumulated other comprehensive income will be reclassified into earnings through straight-line accretion in the same periods the hedged forecasted transaction affects earnings. At March 31, 2017 , net derivative assets included $7.4 million of cash collateral received from counterparties under master netting agreements and net derivative liabilities included $408,000 of cash collateral held by a counterparty to a master netting agreement. At March 31, 2017 , we had $42,000 of cash collateral receivable that was not offset against derivative liabilities. 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. For derivative instruments not designated as hedging instruments, the gain or loss is recognized in current earnings during the period of change. 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. 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 for the periods presented (in thousands): March 31, 2017 December 31, 2016 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 $ 240,000 $ 7,404 $ 36 $ 250,000 $ 7,069 $ — Derivatives designated as non-hedging instruments Interest rate contracts: Swaps-Financial institution counterparties 46,196 91 499 2,182 85 — Swaps-Customer counterparties 46,196 499 91 2,182 — 85 Gross derivatives 7,994 626 7,154 85 Offsetting derivative assets/liabilities (127 ) (127 ) — — Cash collateral received/posted (7,360 ) (408 ) (7,154 ) — Net derivatives included in the consolidated balance sheets (2) $ 507 $ 91 $ — $ 85 (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 net credit exposure of $8,000 related to interest rate swaps with financial institutions and $499,000 related to interest rate swaps with customers at March 31, 2017 . The credit risk associated with customer transactions is partially mitigated as these transactions are generally secured by the non-cash collateral securing the underlying transaction being hedged. We had no credit exposure related to interest rate swaps with financial or customer counterparties at December 31, 2016 . 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 pay fixed swaps are based on one-month or three-month LIBOR rates in effect at March 31, 2017 and December 31, 2016 : March 31, 2017 December 31, 2016 Weighted Average Weighted Average Notional Amount Remaining Maturity (in years) Receive Rate Pay Rate Notional Amount Remaining Maturity Receive Rate Pay Swaps-Cash Flow Hedge Financial institution counterparties $ 240,000 6.0 0.91 % 1.43 % $ 250,000 5.4 0.68 % 1.31 % Swaps-Non-Hedging Financial institution counterparties 46,196 10.3 0.83 2.32 2,182 9.7 0.62 1.57 Customer counterparties 46,196 10.3 2.32 0.83 2,182 9.7 1.57 0.62

Fair Value Measurement

Fair Value Measurement	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that 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 that market participants would use in pricing the asset or liability. Valuation policies and procedures are determined by our investment department and reported to our Asset/Liability Committee (“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. Level 3 assets recorded at fair value on a nonrecurring basis at March 31, 2017 and December 31, 2016 , included loans for which a specific allowance was established based on the fair value of collateral and commercial real estate for which fair value of the properties was less than the cost basis. For both asset classes, the unobservable inputs were the additional adjustments applied by management to the appraised values to reflect such factors as non-current appraisals and revisions to estimated time to sell. These adjustments are determined based on qualitative judgments made by management on a case-by-case basis and are not quantifiable inputs, although they are used in the determination of fair value. 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. 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. Transfers between levels of the fair value hierarchy are recognized on the actual date of the event or circumstances that caused the transfer, which generally coincides with our monthly and/or quarterly valuation process. There were no transfers between Level 1 and Level 2 during the three months ended March 31, 2017 or the year ended December 31, 2016 . Securities Available for Sale – U.S. Treasury securities and other equity securities are reported at fair value utilizing Level 1 inputs. Other securities classified as available for sale are reported at fair value utilizing Level 2 inputs. For these securities, we obtain fair value measurements from 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. We review the prices supplied by the independent pricing services for reasonableness and to ensure such prices are aligned with traditional pricing matrices. In addition, we obtain an understanding of their underlying pricing methodologies and their Statement on Standards for Attestation Engagements-Reporting on Controls of a Service Organization (“SSAE 16”). We validate prices supplied by the independent pricing services by comparison to prices obtained from, in most cases, three additional third party sources. For securities where prices are outside a reasonable range, we further review those securities to determine what a reasonable price estimate is for that security, given available data. Derivatives – Derivatives are reported at fair value utilizing Level 2 inputs. We obtain fair value measurements from three 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 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 impaired loans at March 31, 2017 and December 31, 2016 . 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 loan losses. Impaired Loans – Certain impaired loans may be reported at the fair value of the underlying collateral if repayment is expected solely from the collateral. Collateral values are estimated using Level 3 inputs based on customized discounting criteria or appraisals. At March 31, 2017 and December 31, 2016 , the impact of loans with specific reserves based on the fair value of the collateral was reflected in our allowance for loan losses. 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. 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): As of March 31, 2017 Fair Value Measurements at the End of the Reporting Period Using 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 $ 59,214 $ 59,214 $ — $ — State and Political Subdivisions 320,847 — 320,847 — Other Stocks and Bonds 6,658 — 6,658 — Other Equity Securities 5,920 5,920 — — Mortgage-backed Securities: (1) Residential 684,662 — 684,662 — Commercial 366,742 — 366,742 — Derivative assets: Interest rate swaps 7,994 — 7,994 — Total asset recurring fair value measurements $ 1,452,037 $ 65,134 $ 1,386,903 $ — Derivative liabilities: Interest rate swaps $ 626 $ — $ 626 $ — Total liability recurring fair value measurements $ 626 $ — $ 626 $ — Nonrecurring fair value measurements Foreclosed assets $ 393 $ — $ — $ 393 Impaired loans (2) 9,137 — — 9,137 Total asset nonrecurring fair value measurements $ 9,530 $ — $ — $ 9,530 As of December 31, 2016 Fair Value Measurements at the End of the Reporting Period Using 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 $ 70,069 $ 70,069 $ — $ — State and Political Subdivisions 385,197 — 385,197 — Other Stocks and Bonds 6,651 — 6,651 — Other Equity Securities 5,920 5,920 — — Mortgage-backed Securities: (1) Residential 627,508 — 627,508 — Commercial 384,255 — 384,255 — Derivative assets: Interest rate swaps 7,154 — 7,154 — Total asset recurring fair value measurements $ 1,486,754 $ 75,989 $ 1,410,765 $ — Derivative liabilities: Interest rate swaps $ 85 $ — $ 85 $ — Total liability recurring fair value measurements $ 85 $ — $ 85 $ — Nonrecurring fair value measurements Foreclosed assets $ 388 $ — $ — $ 388 Impaired loans (2) 9,693 — — 9,693 Total asset nonrecurring fair value measurements $ 10,081 $ — $ — $ 10,081 (1) All mortgage-backed securities are issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. (2) Impaired loans represent collateral-dependent loans with a specific valuation 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 mortgage - backed securities held to maturity - 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 and other investments - The carrying amount of FHLB stock and other investments is a reasonable estimate of the fair value of those assets. Loans receivable - For adjustable rate loans that reprice frequently and with no significant change in credit risk, the carrying amounts are a reasonable estimate of those assets’ fair value. The fair value of fixed rate loans is estimated by discounting the future cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings and for the same remaining maturities. Nonperforming loans are 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. Federal funds purchased and repurchase agreements - 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 advances - The fair value of these advances is estimated by discounting the future cash flows using rates at which advances 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. Long-term debt - 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, financial liabilities, and unrecognized financial instruments measured on a nonrecurring basis at both their respective carrying amounts and estimated fair value (in thousands): Estimated Fair Value March 31, 2017 Carrying Total Level 1 Level 2 Level 3 Financial Assets: Cash and cash equivalents $ 246,994 $ 246,994 $ 246,994 $ — $ — Investment Securities: Held to maturity, at carrying value 421,133 427,288 — 427,288 — Mortgage-backed Securities: Held to maturity, at carrying value 508,660 513,121 — 513,121 — FHLB stock, at cost, and other investments 66,747 66,747 — 66,747 — Loans, net of allowance for loan losses 2,520,433 2,601,382 — — 2,601,382 Loans held for sale 5,303 5,303 — 5,303 — Financial Liabilities: Deposits $ 3,705,296 $ 3,701,697 $ — $ 3,701,697 $ — Federal funds purchased and repurchase agreements 7,814 7,814 — 7,814 — FHLB advances 1,205,856 1,206,415 — 1,206,415 — Subordinated notes, net of unamortized debt issuance costs 98,133 100,561 — 100,561 — Long-term debt , net of unamortized debt issuance costs 60,237 45,572 — 45,572 — Estimated Fair Value December 31, 2016 Carrying Total Level 1 Level 2 Level 3 Financial Assets: Cash and cash equivalents $ 169,654 $ 169,654 $ 169,654 $ — $ — Investment Securities: Held to maturity, at carrying value 425,810 429,912 — 429,912 — Mortgage-backed Securities: Held to maturity, at carrying value 511,677 514,370 — 514,370 — FHLB stock, at cost, and other investments 66,592 66,592 — 66,592 — Loans, net of allowance for loan losses 2,538,626 2,630,009 — — 2,630,009 Loans held for sale 7,641 7,641 — 7,641 — Financial Liabilities: Deposits $ 3,533,076 $ 3,293,352 $ — $ 3,293,352 $ — Federal funds purchased and repurchase agreements 7,097 7,097 — 7,097 — FHLB advances 1,309,646 1,331,517 — 1,331,517 — Subordinated notes, net of unamortized debt issuance costs 98,100 101,627 — 101,627 — Long-term debt , net of unamortized debt issuance costs 60,236 45,147 — 45,147 — 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 above fair value table do not necessarily represent their underlying value.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The income tax expense included in the accompanying statements of income consists of the following (in thousands): Three Months Ended 2017 2016 Current income tax expense $ 3,027 $ 3,785 Deferred income tax (benefit) expense (19 ) (812 ) Income tax expense $ 3,008 $ 2,973 Net deferred tax assets totaled $26.8 million at March 31, 2017 and $28.9 million at December 31, 2016 . No valuation allowance for deferred tax assets was recorded at March 31, 2017 or December 31, 2016 , as management believes it is more likely than not that all of the deferred tax assets will be realized in future years. Unrecognized tax benefits were not material at March 31, 2017 or December 31, 2016 . During the first quarter of 2017, we adopted a new accounting standard that impacted how the income tax effects associated with stock-based compensation are recognized. See “Note 1 - Summary of Significant Accounting and Reporting Policies” for additional information. We recognized income tax expense of $3.0 million for both the three months ended March 31, 2017 and March 31, 2016 , for an effective tax rate (“ETR”) of 16.7% and 18.0% , respectively. The adoption of the accounting standard above reduced income tax expense by $126,000 and the ETR by 0.7% for the three months ended March 31, 2017. The lower ETR for the three months ended March 31, 2017 was due largely to an increase in tax-exempt income as a percentage of pre-tax income as compared to the same period in 2016 . The ETR differs from the stated rate of 35% during the comparable period primarily due to the effect of tax-exempt income from municipal loans and securities, as well as bank owned life insurance. We file federal income tax returns and certain state tax returns. We are no longer subject to U.S. federal income tax examinations by tax authorities for years before 2013 .

Off-Balance-Sheet Arrangements,

Off-Balance-Sheet Arrangements, Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
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. Commitments to extend credit are agreements to lend to a customer provided that the terms established in the contract are met. Commitments 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 extending loan commitments to customers and similarly do not necessarily represent future cash obligations. Financial instruments with off-balance-sheet risk were as follows (in thousands): At At Unused commitments: Commitments to extend credit $ 666,207 $ 665,663 Standby letters of credit 8,612 9,075 Total $ 674,819 $ 674,738 We apply the same credit policies in making commitments 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. Lease Commitments . We lease certain branch facilities and office equipment under operating leases. It is expected that certain leases will be renewed, or equipment replaced with new leased equipment, as these leases expire. Securities . In the normal course of business we buy and sell securities. There were $10.5 million and $160,000 of unsettled trades to purchase securities at March 31, 2017 and December 31, 2016 , respectively. There were $57.4 million unsettled trades to sell securities as of March 31, 2017 . As of December 31, 2016 , there were no unsettled trades to sell securities. Deposits . There were $31.2 million of unsettled issuances of brokered CDs at March 31, 2017 . There were no unsettled issuances of brokered CDs at December 31, 2016 . Litigation . We are a party to 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 Accoun20

Summary of Significant Accounting and Reporting Policies (Policies)	3 Months Ended
	Mar. 31, 2017
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. The words “Southside” and “Southside Bancshares” refer to Southside Bancshares, Inc. The words “Southside Bank” and “the Bank” refer to Southside Bank. “Omni” refers to OmniAmerican Bancorp, Inc., a bank holding company acquired by Southside on December 17, 2014. The consolidated balance sheet as of March 31, 2017 , and the related consolidated statements of income, comprehensive income, changes in shareholders’ equity, cash flows and notes to the financial statements for the three- month periods ended March 31, 2017 and 2016 are unaudited; 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. All intercompany accounts and transactions are eliminated in consolidation. The preparation of these consolidated financial statements in conformity with U.S. generally accepted accounting principles (“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, 2016 . Accounting Changes and Reclassifications Certain prior period amounts have been reclassified to conform to current year presentation. We adopted ASU 2016-09 “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,” on January 1, 2017 which requires all income tax effects related to settlements of share-based payment awards be reported in earnings as an increase (or decrease) to income tax expense. Previously, income tax benefits at settlement of an award were reported as an increase (or decrease) to additional paid-in capital to the extent that those benefits were greater than (or less than) the income tax benefits recognized in earnings during the vesting period or exercise of the award. The requirement to report those income tax effects in earnings has been applied to settlements occurring on or after January 1, 2017, and the impact of applying that guidance reduced reported income tax expense by $126,000 , or less than $0.01 on our diluted earnings per common share. ASU 2016-09 also requires that all income tax-related cash flows resulting from share-based payments be reported as operating activities in the statement of cash flows. Previously, income tax benefits at settlement of an award were reported as a reduction to operating cash flows and an increase to financing cash flows to the extent that those benefits exceeded the income tax benefits reported in earnings during the vesting period or exercise of the award. We have elected to apply that change in cash flow on a prospective basis and therefore, prior periods have not been adjusted. ASU 2016-09 also requires the classification of employee taxes paid when an employer withholds shares for tax withholding purposes be classified as a financing activity in the statement of cash flow and be applied retrospectively. The requirement to report the employee taxes paid is reflected in prior period presentation in our consolidated statement of cash flows. In connection with the adoption of ASU 2016-09, we have also elected to recognize forfeitures as they occur.
Terminated Derivative Financial Instruments	Terminated Derivative Financial Instruments 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 accumulated other comprehensive income will continue to be reclassified into earnings during the period or periods in which the hedged forecasted transaction affects earnings unless it is probable that the forecasted transaction will not occur by the end of the originally specified time period. If the forecasted transaction is deemed probable to not occur, the derivative gain or loss reported in accumulated other comprehensive income shall be reclassified into earnings immediately. During the first quarter of 2017, we terminated two interest rate swap contracts designated as cash flow hedges. At the time of termination, we determined that the underlying hedged forecasted transactions were still probable of occurring. The existing gain in accumulated other comprehensive income related to the terminated interest rate swap contracts will be reclassified into earnings through straight-line accretion in the same periods the hedged forecasted transaction affects earnings. Further information on our derivative instruments and hedging activities is included in “Note 8 - Derivative Financial Instruments and Hedging Activities.”
Accounting Pronouncements	Accounting Pronouncements In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” This update states that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update affects entities that enter into contracts with customers to transfer goods or services or enter into contracts for the transfer of nonfinancial assets, unless those contracts are within the scope of other standards. In August 2015, the FASB issued ASU 2015-14, “Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date,” which effectively delayed the adoption date by one year. We are required to adopt ASU 2014-09 in the first quarter of fiscal 2018. Early adoption is permitted. The guidance permits companies to either apply the requirements retrospectively to all prior periods presented, or apply the requirements in the year of adoption, through cumulative adjustment. Our revenue consists of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and noninterest income. We are currently evaluating the impact this guidance will have in relation to our noninterest income derived from contracts with our customers as it relates to deposit services, trust income, brokerage services, and merchant services (included in other noninterest income) which we have determined to be in the scope of ASU 2014-09. We anticipate our assessment for these areas to be completed during the second quarter of 2017 at which time we will select the transition method to be applied upon adoption. We are concurrently evaluating the impact and resources needed to fulfill the additional disclosures required by this guidance. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” ASU 2016-02 requires a lessee to recognize assets and liabilities for leases with lease terms of more than 12 months. Consistent with current GAAP, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance or operating lease. However, unlike current GAAP which requires only capital leases to be recognized on the balance sheet, the new ASU 2016-02 will require both finance (formerly known as “capital”) and operating leases to be recognized on the balance sheet. ASU 2016-02 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The guidance requires companies to apply the requirements in the year of adoption using a modified retrospective approach. We are currently evaluating the impact this guidance will have on our financial statements and we anticipate our assessment to be completed during the fiscal year 2018. In June 2016, the FASB issued ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” ASU 2016-13 introduces an approach based on expected losses to estimate credit losses on certain types of financial instruments. ASU 2016-13 also modifies the impairment model for available for sale debt securities and provides for a simplified accounting model for purchased financial assets with credit deterioration since their origination. ASU 2016-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The guidance requires companies to apply the requirements in the year of adoption through cumulative adjustment with some aspects of the update requiring a prospective transition approach. We are currently evaluating the potential impact of the pending adoption of ASU 2016-13 on our consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” ASU 2017-04 is intended to simplify goodwill impairment testing by eliminating the second step of the analysis which requires the calculation of the implied fair value of goodwill to measure a goodwill impairment charge. The update requires entities to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit’s fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. ASU 2017-04 is effective for annual and interim goodwill impairment tests performed in periods beginning after December 15, 2019. Early adoption is permitted for annual and interim goodwill impairment testing dates after January 1, 2017. The guidance requires companies to apply the requirements prospectively in the year of adoption. ASU 2017-04 is not expected to have a significant impact on our consolidated financial statements. In March 2017, the FASB issued ASU 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.” ASU 2017-07 requires employers to present the service cost component of net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Only the service cost component will be eligible for capitalization in assets. Employers are required to present the other components of the net periodic benefit cost separately from the line item that includes the service cost and outside of any subtotal of operating income, if one is presented. ASU 2017-07 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Early adoption is permitted as of the beginning of an annual period for which financial statements (interim or annual) have not been issued or made available for issuance. We did not early adopt. The guidance requires companies to apply the requirements retrospectively to all prior periods presented. We are currently evaluating the potential impact of the pending adoption of ASU 2017-07 on our consolidated financial statements. In March 2017, the FASB issued ASU 2017-08, “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.” Under current GAAP, premiums on callable debt securities are generally amortized over the contractual life of the security. ASU 2017-08 requires the premium on callable debt securities to be amortized to the earliest call date. If the debt security is not called at the earliest call date, the holder of the debt security would be required to reset the effective yield on the debt security based on the payment terms required by the debt security. ASU 2017-08 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The guidance requires companies to apply the requirements on a modified retrospective basis through a cumulative adjustment directly to retained earnings as of the beginning of the period of adoption. We are currently evaluating the potential impact of the pending adoption of ASU 2017-08 on our consolidated financial statements.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Earnings per share on a basic and diluted basis	Earnings per share on a basic and diluted basis has been adjusted to give retroactive recognition to stock dividends and is calculated as follows (in thousands, except per share amounts): Three Months Ended 2017 2016 Basic and Diluted Earnings: Net income $ 14,989 $ 13,516 Basic weighted-average shares outstanding 28,569 26,449 Add: Stock awards 208 70 Diluted weighted-average shares outstanding 28,777 26,519 Basic Earnings Per Share: Net Income $ 0.52 $ 0.51 Diluted Earnings Per Share: Net Income $ 0.52 $ 0.51

Accumulated Other Comprehensi22

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2017
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, 2017 Pension Plans Unrealized Gains (Losses) on Securities Unrealized Gains (Losses) on Derivatives Net Prior Net Gain (Loss) Total Beginning balance, net of tax $ (23,708 ) $ 4,595 $ (133 ) $ (19,247 ) $ (38,493 ) Other comprehensive income (loss): Other comprehensive income before reclassifications 4,885 193 — — 5,078 Reclassified from accumulated other comprehensive income 166 370 (2 ) 391 925 Income tax (expense) benefit (1,768 ) (197 ) 1 (137 ) (2,101 ) Net current-period other comprehensive income (loss), net of tax 3,283 366 (1 ) 254 3,902 Ending balance, net of tax $ (20,425 ) $ 4,961 $ (134 ) $ (18,993 ) $ (34,591 ) Three Months Ended March 31, 2016 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 $ (239 ) $ — $ (44 ) $ (18,400 ) $ (18,683 ) Other comprehensive income (loss): Other comprehensive income (loss) before reclassifications 27,744 (2,601 ) — — 25,143 Reclassified from accumulated other comprehensive income (2,384 ) 357 (4 ) 411 (1,620 ) Income tax (expense) benefit (8,876 ) 785 1 (143 ) (8,233 ) Net current-period other comprehensive income (loss), net of tax 16,484 (1,459 ) (3 ) 268 15,290 Ending balance, net of tax $ 16,245 $ (1,459 ) $ (47 ) $ (18,132 ) $ (3,393 )
Reclassifications out of accumulated other comprehensive income	The reclassifications out of accumulated other comprehensive income (loss) into net income are presented below (in thousands): Three Months Ended 2017 2016 Unrealized losses on securities transferred to held to maturity: Amortization of unrealized losses (1) $ (488 ) $ (57 ) Tax benefit 171 20 Net of tax $ (317 ) $ (37 ) Unrealized gains and losses on available for sale securities: Realized net gain on sale of securities (2) $ 322 $ 2,441 Tax expense (113 ) (854 ) Net of tax $ 209 $ 1,587 Derivatives: Realized net loss on interest rate swap derivatives (3) $ (379 ) $ (357 ) Tax benefit 133 125 Net of tax $ (246 ) $ (232 ) Amortization of unrealized gains on terminated interest rate swap derivatives (3) $ 9 $ — Tax expense (3 ) — Net of tax $ 6 $ — Amortization of pension plan: Net actuarial loss (4) $ (391 ) $ (411 ) Prior service credit (4) 2 4 Total before tax (389 ) (407 ) Tax benefit 136 142 Net of tax (253 ) (265 ) Total reclassifications for the period, net of tax $ (601 ) $ 1,053 (1) Included in interest income on the consolidated statements of income. (2) Listed as net gain on sale of securities available for sale on the consolidated statements of income. (3) Included in interest expense for long-term obligations on the consolidated statements of income. (4) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (income) presented in “Note 7 - Employee Benefit Plans.”

Securities (Tables)

Securities (Tables)	3 Months Ended
	Mar. 31, 2017
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, carrying value, and estimated fair value of investment and mortgage-backed securities as of March 31, 2017 and December 31, 2016 are reflected in the tables below (in thousands): March 31, 2017 Recognized in OCI Not recognized in OCI Amortized Gross Unrealized Gross Unrealized Carrying Gross Gross Unrealized Estimated AVAILABLE FOR SALE Cost Gains Losses Value Gains Losses Fair Value Investment Securities: U.S. Treasury $ 62,015 $ — $ 2,801 $ 59,214 $ — $ — $ 59,214 State and Political Subdivisions 328,395 3,227 10,775 320,847 — — 320,847 Other Stocks and Bonds 6,574 84 — 6,658 — — 6,658 Other Equity Securities 6,036 — 116 5,920 — — 5,920 Mortgage-backed Securities: (1) Residential 685,934 6,621 7,893 684,662 — — 684,662 Commercial 368,330 896 2,484 366,742 — — 366,742 Total $ 1,457,284 $ 10,828 $ 24,069 $ 1,444,043 $ — $ — $ 1,444,043 HELD TO MATURITY Investment Securities: State and Political Subdivisions $ 430,350 $ 3,631 $ 12,848 $ 421,133 $ 8,902 $ 2,747 $ 427,288 Mortgage-backed Securities: (1) Residential 137,693 — 5,478 132,215 1,536 370 133,381 Commercial 379,931 1,025 4,511 376,445 4,952 1,657 379,740 Total $ 947,974 $ 4,656 $ 22,837 $ 929,793 $ 15,390 $ 4,774 $ 940,409 December 31, 2016 Recognized in OCI Not recognized in OCI Amortized Gross Unrealized Gross Unrealized Carrying Gross Gross Unrealized Estimated AVAILABLE FOR SALE Cost Gains Losses Value Gains Losses Fair Value Investment Securities: U.S. Treasury $ 74,016 $ — $ 3,947 $ 70,069 $ — $ — $ 70,069 State and Political Subdivisions 394,050 3,217 12,070 385,197 — — 385,197 Other Stocks and Bonds 6,587 64 — 6,651 — — 6,651 Other Equity Securities 6,039 — 119 5,920 — — 5,920 Mortgage-backed Securities: (1) Residential 630,603 6,434 9,529 627,508 — — 627,508 Commercial 386,109 1,201 3,055 384,255 — — 384,255 Total $ 1,497,404 $ 10,916 $ 28,720 $ 1,479,600 $ — $ — $ 1,479,600 HELD TO MATURITY Investment Securities: State and Political Subdivisions $ 435,080 $ 3,987 $ 13,257 $ 425,810 $ 7,595 $ 3,493 $ 429,912 Mortgage-backed Securities: (1) Residential 142,060 — 5,748 136,312 1,534 950 136,896 Commercial 379,016 1,067 4,718 375,365 4,372 2,263 377,474 Total $ 956,156 $ 5,054 $ 23,723 $ 937,487 $ 13,501 $ 6,706 $ 944,282 (1) All mortgage-backed securities issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
Unrealized loss on securities	The following tables represent the estimated fair value and unrealized loss on securities as of March 31, 2017 and December 31, 2016 (in thousands): As of March 31, 2017 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 $ 59,214 $ 2,801 $ — $ — $ 59,214 $ 2,801 State and Political Subdivisions 209,637 10,774 886 1 210,523 10,775 Other Equity Securities 5,920 116 — — 5,920 116 Mortgage-backed Securities: Residential 361,710 7,887 2,344 6 364,054 7,893 Commercial 248,331 2,484 — — 248,331 2,484 Total $ 884,812 $ 24,062 $ 3,230 $ 7 $ 888,042 $ 24,069 HELD TO MATURITY Investment Securities: State and Political Subdivisions $ 99,422 $ 1,372 $ 25,976 $ 1,375 $ 125,398 $ 2,747 Mortgage-backed Securities: Residential 55,917 370 — — 55,917 370 Commercial 172,138 1,657 — — 172,138 1,657 Total $ 327,477 $ 3,399 $ 25,976 $ 1,375 $ 353,453 $ 4,774 As of December 31, 2016 Less Than 12 Months More Than 12 Months Total Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized AVAILABLE FOR SALE Investment Securities: U.S. Treasury $ 70,069 $ 3,947 $ — $ — $ 70,069 $ 3,947 State and Political Subdivisions 264,485 12,069 887 1 265,372 12,070 Other Equity Securities 5,920 119 — — 5,920 119 Mortgage-backed Securities: Residential 369,903 9,491 6,199 38 376,102 9,529 Commercial 245,422 3,055 — — 245,422 3,055 Total $ 955,799 $ 28,681 $ 7,086 $ 39 $ 962,885 $ 28,720 HELD TO MATURITY Investment Securities: State and Political Subdivisions $ 179,939 $ 2,190 $ 29,427 $ 1,303 $ 209,366 $ 3,493 Mortgage-backed Securities: Residential 107,024 950 — — 107,024 950 Commercial 186,854 2,263 — — 186,854 2,263 Total $ 473,817 $ 5,403 $ 29,427 $ 1,303 $ 503,244 $ 6,706
Interest income recognized on securities	Interest income recognized on securities for the periods presented (in thousands): Three Months Ended 2017 2016 U.S. Treasury $ 315 $ 127 State and Political Subdivisions 6,554 5,355 Other Stocks and Bonds 34 58 Other Equity Securities 28 29 Mortgage-backed Securities 10,045 9,391 Total interest income on securities $ 16,976 $ 14,960
Amortized cost, carrying value and fair value of securities presented by contractual maturity	The amortized cost, carrying value and estimated fair value of securities at March 31, 2017 , are presented below by contractual maturity (in thousands). Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations. MBS are presented in total by category due to the fact that MBS typically are issued with stated principal amounts, and the securities 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. March 31, 2017 Amortized Cost Fair Value AVAILABLE FOR SALE Investment Securities: Due in one year or less $ 6,694 $ 6,851 Due after one year through five years 23,638 24,655 Due after five years through ten years 96,416 93,961 Due after ten years 270,236 261,252 396,984 386,719 Mortgage-backed Securities and Other Equity Securities: 1,060,300 1,057,324 Total $ 1,457,284 $ 1,444,043 March 31, 2017 Carrying Value Fair Value HELD TO MATURITY Investment Securities: Due in one year or less $ 10,119 $ 10,181 Due after one year through five years 39,539 39,935 Due after five years through ten years 101,274 101,898 Due after ten years 270,201 275,274 421,133 427,288 Mortgage-backed Securities: 508,660 513,121 Total $ 929,793 $ 940,409

Loans and Allowance for Proba24

Loans and Allowance for Probable Loan Losses (Tables)	3 Months Ended
	Mar. 31, 2017
Receivables [Abstract]
Classification of loans in the consolidated balance sheets	Loans in the accompanying consolidated balance sheets are classified as follows (in thousands): March 31, 2017 December 31, 2016 Real Estate Loans: Construction $ 362,367 $ 380,175 1-4 Family Residential 622,881 637,239 Commercial 974,307 945,978 Commercial Loans 176,908 177,265 Municipal Loans 297,417 298,583 Loans to Individuals 105,038 117,297 Total Loans (1) 2,538,918 2,556,537 Less: Allowance for Loan Losses (2) 18,485 17,911 Net Loans $ 2,520,433 $ 2,538,626 (1) Includes approximately $324.9 million and $372.4 million of loans acquired with the Omni acquisition as of March 31, 2017 and December 31, 2016 , respectively. (2) The allowance for loan loss recorded on purchase credit impaired (“PCI”) loans totaled $3,000 as of March 31, 2017 and December 31, 2016 .
Activity in the allowance for loan losses 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, 2017 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Balance at beginning of period $ 4,147 $ 2,665 $ 7,204 $ 2,263 $ 750 $ 882 $ 17,911 Provision (reversal) for loan losses (1) (722 ) (62 ) 1,577 (112 ) (4 ) 421 1,098 Loans charged off (18 ) (287 ) — (3 ) — (746 ) (1,054 ) Recoveries of loans charged off — 1 6 111 — 412 530 Balance at end of period $ 3,407 $ 2,317 $ 8,787 $ 2,259 $ 746 $ 969 $ 18,485 Three Months Ended March 31, 2016 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Balance at beginning of period $ 4,350 $ 2,595 $ 4,577 $ 6,596 $ 725 $ 893 $ 19,736 Provision (reversal) for loan losses (1) (42 ) (551 ) (116 ) 2,620 (5 ) 410 2,316 Loans charged off — (19 ) — (273 ) — (848 ) (1,140 ) Recoveries of loans charged off 269 130 6 21 — 461 887 Balance at end of period $ 4,577 $ 2,155 $ 4,467 $ 8,964 $ 720 $ 916 $ 21,799 (1) Of the $1.1 million and $2.3 million recorded in provision for loan losses for the three months ended March 31, 2017 and March 31, 2016 , none related to provision expense on PCI loans as of March 31, 2017 and $296,000 related to provision expense on PCI loans as of March 31, 2016 .
Balance in the allowance for loan losses by portfolio segment based on impairment method	The following tables present the balance in the allowance for loan losses by portfolio segment based on impairment method (in thousands): As of March 31, 2017 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Ending balance – individually evaluated for impairment (1) $ 10 $ 13 $ 15 $ 982 $ 11 $ 91 $ 1,122 Ending balance – collectively evaluated for impairment 3,397 2,304 8,772 1,277 735 878 17,363 Balance at end of period $ 3,407 $ 2,317 $ 8,787 $ 2,259 $ 746 $ 969 $ 18,485 As of December 31, 2016 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Ending balance – individually evaluated for impairment (1) $ 13 $ 16 $ 17 $ 923 $ 11 $ 106 $ 1,086 Ending balance – collectively evaluated for impairment 4,134 2,649 7,187 1,340 739 776 16,825 Balance at end of period $ 4,147 $ 2,665 $ 7,204 $ 2,263 $ 750 $ 882 $ 17,911 (1) There was approximately $3,000 of allowance for loan losses associated with PCI loans as of March 31, 2017 and December 31, 2016 .
Balance in recorded investments in loans by portfolio segment based on impairment method	The following tables present the recorded investment in loans by portfolio segment based on impairment method (in thousands): March 31, 2017 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Loans individually evaluated for impairment $ 430 $ 1,672 $ 1,081 $ 5,529 $ 571 $ 225 $ 9,508 Loans collectively evaluated for impairment 361,784 615,628 971,593 170,090 296,846 104,712 2,520,653 Purchased credit impaired loans 153 5,581 1,633 1,289 — 101 8,757 Total ending loan balance $ 362,367 $ 622,881 $ 974,307 $ 176,908 $ 297,417 $ 105,038 $ 2,538,918 December 31, 2016 Real Estate Construction 1-4 Family Residential Commercial Commercial Loans Municipal Loans Loans to Individuals Total Loans individually evaluated for impairment $ 480 $ 1,693 $ 1,184 $ 5,840 $ 571 $ 241 $ 10,009 Loans collectively evaluated for impairment 379,526 629,893 942,818 170,159 298,012 116,923 2,537,331 Purchased credit impaired loans 169 5,653 1,976 1,266 — 133 9,197 Total ending loan balance $ 380,175 $ 637,239 $ 945,978 $ 177,265 $ 298,583 $ 117,297 $ 2,556,537
Summary of loans by credit quality indicators	The following tables set forth credit quality indicators by class of loans for the periods presented (in thousands): March 31, 2017 Pass Pass Watch (1) Special Mention (1) Substandard (1) Doubtful (1) Total Real Estate Loans: Construction $ 358,837 $ 33 $ 159 $ 3,320 $ 18 $ 362,367 1-4 Family Residential 618,810 14 — 3,626 431 622,881 Commercial 922,584 3,258 8,657 39,808 — 974,307 Commercial Loans 162,780 1,167 4,372 8,544 45 176,908 Municipal Loans 295,896 — 950 571 — 297,417 Loans to Individuals 103,874 — 27 650 487 105,038 Total $ 2,462,781 $ 4,472 $ 14,165 $ 56,519 $ 981 $ 2,538,918 December 31, 2016 Pass Pass Watch (1) Special Mention (1) Substandard (1) Doubtful (1) Total Real Estate Loans: Construction $ 374,443 $ 34 $ 571 $ 5,108 $ 19 $ 380,175 1-4 Family Residential 632,937 68 — 3,380 854 637,239 Commercial 885,049 17,739 10,587 32,603 — 945,978 Commercial Loans 158,943 1,187 8,086 9,012 37 177,265 Municipal Loans 297,014 — 998 571 — 298,583 Loans to Individuals 115,952 — 9 629 707 117,297 Total $ 2,464,338 $ 19,028 $ 20,251 $ 51,303 $ 1,617 $ 2,556,537 (1) Includes PCI loans comprised of $5,000 pass watch, $507,000 special mention, $1.1 million substandard and $28,000 doubtful as of March 31, 2017 . Includes PCI loans comprised of $5,000 pass watch, $511,000 special mention, $1.5 million substandard and $28,000 doubtful as of December 31, 2016
Summary of nonperforming assets for the period	The following table sets forth nonperforming assets for the periods presented (in thousands): At At Nonaccrual loans (1) $ 7,261 $ 8,280 Accruing loans past due more than 90 days (1) 1 6 Restructured loans (2) 6,424 6,431 Other real estate owned 367 339 Repossessed assets 26 49 Total Nonperforming Assets $ 14,079 $ 15,105 (1) Excludes PCI loans measured at fair value at acquisition. (2) Includes $3.0 million and $3.1 million in PCI loans restructured as of March 31, 2017 and December 31, 2016 , respectively.
Recorded investment in nonaccrual by class of loans	The following table sets forth the recorded investment in nonaccrual loans by class of loans for the periods presented (in thousands). The table ex cludes PCI loans measured at fair value at acquisition : Nonaccrual Loans March 31, 2017 December 31, 2016 Real Estate Loans: Construction $ 55 $ 105 1-4 Family Residential 673 1,067 Commercial 723 808 Commercial Loans 5,127 5,477 Loans to Individuals 683 823 Total $ 7,261 $ 8,280
Summary of impaired loans by class of loans for the period	The following tables set forth impaired loans by class of loans for the periods presented (in thousands). Impaired loans include restructured and nonaccrual loans for which the allowance was measured in accordance with section 310-10 of ASC Topic 310, “Receivables.” There were no impaired loans recorded without an allowance as of March 31, 2017 or December 31, 2016 . March 31, 2017 Unpaid Contractual Principal Balance Recorded Investment Related Allowance for Loan Losses Real Estate Loans: Construction $ 437 $ 430 $ 10 1-4 Family Residential 4,429 4,221 13 Commercial 1,530 1,465 15 Commercial Loans 5,798 5,638 982 Municipal Loans 571 571 11 Loans to Individuals 256 225 91 Total (1) $ 13,021 $ 12,550 $ 1,122 December 31, 2016 Unpaid Contractual Principal Balance Recorded Investment Related Allowance for Loan Losses Real Estate Loans: Construction $ 486 $ 480 $ 13 1-4 Family Residential 4,487 4,264 16 Commercial 1,631 1,574 17 Commercial Loans 6,108 5,941 923 Municipal Loans 571 571 11 Loans to Individuals 277 241 106 Total (1) $ 13,560 $ 13,071 $ 1,086 (1) Includes $3.0 million and $3.1 million of PCI loans that experienced deterioration in credit quality subsequent to the acquisition date as of March 31, 2017 and December 31, 2016 , respectively.
Aging of recorded investment in past due loans by class of loans	The following tables present the aging of the recorded investment in past due loans by class of loans (in thousands): March 31, 2017 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days Past Due Total Past Due Current (1) Total Real Estate Loans: Construction $ 2,423 $ — $ 22 $ 2,445 $ 359,922 $ 362,367 1-4 Family Residential 5,330 81 329 5,740 617,141 622,881 Commercial 1,179 151 81 1,411 972,896 974,307 Commercial Loans 2,020 686 2,707 5,413 171,495 176,908 Municipal Loans 663 — — 663 296,754 297,417 Loans to Individuals 850 108 267 1,225 103,813 105,038 Total $ 12,465 $ 1,026 $ 3,406 $ 16,897 $ 2,522,021 $ 2,538,918 December 31, 2016 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days Past Due Total Past Due Current (1) Total Real Estate Loans: Construction $ 917 $ 64 $ 86 $ 1,067 $ 379,108 $ 380,175 1-4 Family Residential 6,225 755 600 7,580 629,659 637,239 Commercial 70 154 154 378 945,600 945,978 Commercial Loans 783 300 3,459 4,542 172,723 177,265 Municipal Loans 113 — — 113 298,470 298,583 Loans to Individuals 1,550 320 185 2,055 115,242 117,297 Total $ 9,658 $ 1,593 $ 4,484 $ 15,735 $ 2,540,802 $ 2,556,537 (1) Includes PCI loans measured at fair value at acquisition.
Average recorded investment and interest income on impaired loans	The following table sets forth average recorded investment and interest income recognized on impaired loans by class of loans for the periods presented (in thousands). The table excludes PCI loans measured at fair value at acquisition that have not experienced further deterioration in credit quality subsequent to the acquisition date : Three Months Ended March 31, 2017 March 31, 2016 Average Recorded Investment Interest Income Recognized Average Recorded Interest Income Recognized Real Estate Loans: Construction $ 467 $ 4 $ 454 $ 6 1-4 Family Residential 4,262 57 1,865 14 Commercial 1,522 19 5,488 21 Commercial Loans 5,787 19 21,675 167 Municipal Loans 571 8 637 9 Loans to Individuals 265 2 247 2 Total $ 12,874 $ 109 $ 30,366 $ 219
Schedule of recorded investment in loans modified	The following tables set forth the recorded balance of loans considered to be TDRs that were restructured and the type of concession during the periods presented (dollars in thousands): Three Months Ended March 31, 2017 Extend Amortization Period Interest Rate Reductions Combination Total Modifications Number of Loans Commercial Loans $ 47 $ — $ — $ 47 1 Loans to Individuals 5 — 12 17 2 Total $ 52 $ — $ 12 $ 64 3 Three Months Ended March 31, 2016 Extend Amortization Period Interest Rate Reductions Combination Total Modifications Number of Loans Real Estate Loans: Construction $ 554 $ — $ — $ 554 1 Commercial 2,118 — — 2,118 1 Commercial Loans 1,176 — — 1,176 4 Total $ 3,848 $ — $ — $ 3,848 6
Schedule of acquired PCI Loans	The following table presents the outstanding principal balance and carrying value for PCI loans for the periods presented (in thousands): March 31, 2017 December 31, 2016 Outstanding principal balance $ 9,924 $ 10,612 Carrying amount $ 8,757 $ 9,197
Schedule of changes in accretable yield for pci loans	The following table presents the changes in the accretable yield during the periods for PCI loans (in thousands): Three Months Ended 2017 2016 Balance at beginning of period $ 2,480 $ 2,493 Reclassifications (to) from nonaccretable discount 1,819 443 Accretion (296 ) (594 ) Balance at end of period $ 4,003 $ 2,342

Long-term Obligations (Tables)

Long-term Obligations (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Summary of long-term obligation	Long-term obligations are summarized as follows (in thousands): March 31, December 31, Parent Company Subordinated notes: (1) 5.50% Subordinated Notes Due 2026, net of unamortized debt issuance costs (2) $ 98,133 $ 98,100 Total Subordinated notes 98,133 98,100 Long-term debt: (3) Southside Statutory Trust III Due 2033, net of unamortized debt issuance costs (4) 20,545 20,544 Southside Statutory Trust IV Due 2037 (5) 23,196 23,196 Southside Statutory Trust V Due 2037 (6) 12,887 12,887 Magnolia Trust Company I Due 2035 (7) 3,609 3,609 Total Long-term debt 60,237 60,236 Total Parent Company 158,370 158,336 Subsidiaries FHLB advances (8) 252,940 443,128 Total Subsidiaries 252,940 443,128 Total Long-term obligations $ 411,310 $ 601,464 (1) This long-term 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 carries a fixed rate of 5.50% through September 29, 2021 and thereafter, adjusts quarterly at a rate equal to three-month LIBOR plus 429.7 basis points . (3) This long-term debt consists of trust preferred securities that qualify under the risk-based capital guidelines as Tier 1 capital, subject to certain limitations. (4) This debt carries an adjustable rate of 4.08678% through June 29, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 294 basis points . (5) This debt carries an adjustable rate of 2.339% through April 29, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 130 basis points . (6) This debt carries an adjustable rate of 3.38122% through June 14, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 225 basis points . (7) This debt carries an adjustable rate of 2.85344% through May 22, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 180 basis points . (8) At March 31, 2017 , the weighted average cost of these advances was 1.5% . Long-term FHLB advances have maturities ranging from April 2018 through July 2028 .

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2017
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
The components of net periodic benefit cost	The components of net periodic benefit cost (income) are as follows (in thousands): Three Months Ended March 31, Defined Benefit Defined Benefit Pension Plan Acquired Restoration 2017 2016 2017 2016 2017 2016 Service cost $ 358 $ 368 $ — $ — $ 51 $ 47 Interest cost 912 917 45 53 132 135 Expected return on assets (1,512 ) (1,354 ) (54 ) (67 ) — — Net loss amortization 344 358 — — 47 53 Prior service (credit) cost amortization (4 ) (6 ) — — 2 2 Special and contractual termination benefits — 1,520 — — — — Net periodic benefit cost (income) $ 98 $ 1,803 $ (9 ) $ (14 ) $ 232 $ 237

Derivative Financial Instrume27

Derivative Financial Instruments and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]	The following tables present the notional and estimated fair value amount of derivative positions outstanding for the periods presented (in thousands): March 31, 2017 December 31, 2016 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 $ 240,000 $ 7,404 $ 36 $ 250,000 $ 7,069 $ — Derivatives designated as non-hedging instruments Interest rate contracts: Swaps-Financial institution counterparties 46,196 91 499 2,182 85 — Swaps-Customer counterparties 46,196 499 91 2,182 — 85 Gross derivatives 7,994 626 7,154 85 Offsetting derivative assets/liabilities (127 ) (127 ) — — Cash collateral received/posted (7,360 ) (408 ) (7,154 ) — Net derivatives included in the consolidated balance sheets (2) $ 507 $ 91 $ — $ 85 (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 net credit exposure of $8,000 related to interest rate swaps with financial institutions and $499,000 related to interest rate swaps with customers at March 31, 2017 . The credit risk associated with customer transactions is partially mitigated as these transactions are generally secured by the non-cash collateral securing the underlying transaction being hedged. We had no credit exposure related to interest rate swaps with financial or customer counterparties at December 31, 2016 .
Weighted Average Maturity And Interest Rates On Risk Management Interest Rate Swaps [Table Text Block]	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 pay fixed swaps are based on one-month or three-month LIBOR rates in effect at March 31, 2017 and December 31, 2016 : March 31, 2017 December 31, 2016 Weighted Average Weighted Average Notional Amount Remaining Maturity (in years) Receive Rate Pay Rate Notional Amount Remaining Maturity Receive Rate Pay Swaps-Cash Flow Hedge Financial institution counterparties $ 240,000 6.0 0.91 % 1.43 % $ 250,000 5.4 0.68 % 1.31 % Swaps-Non-Hedging Financial institution counterparties 46,196 10.3 0.83 2.32 2,182 9.7 0.62 1.57 Customer counterparties 46,196 10.3 2.32 0.83 2,182 9.7 1.57 0.62

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	3 Months Ended
	Mar. 31, 2017
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): As of March 31, 2017 Fair Value Measurements at the End of the Reporting Period Using 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 $ 59,214 $ 59,214 $ — $ — State and Political Subdivisions 320,847 — 320,847 — Other Stocks and Bonds 6,658 — 6,658 — Other Equity Securities 5,920 5,920 — — Mortgage-backed Securities: (1) Residential 684,662 — 684,662 — Commercial 366,742 — 366,742 — Derivative assets: Interest rate swaps 7,994 — 7,994 — Total asset recurring fair value measurements $ 1,452,037 $ 65,134 $ 1,386,903 $ — Derivative liabilities: Interest rate swaps $ 626 $ — $ 626 $ — Total liability recurring fair value measurements $ 626 $ — $ 626 $ — Nonrecurring fair value measurements Foreclosed assets $ 393 $ — $ — $ 393 Impaired loans (2) 9,137 — — 9,137 Total asset nonrecurring fair value measurements $ 9,530 $ — $ — $ 9,530 As of December 31, 2016 Fair Value Measurements at the End of the Reporting Period Using 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 $ 70,069 $ 70,069 $ — $ — State and Political Subdivisions 385,197 — 385,197 — Other Stocks and Bonds 6,651 — 6,651 — Other Equity Securities 5,920 5,920 — — Mortgage-backed Securities: (1) Residential 627,508 — 627,508 — Commercial 384,255 — 384,255 — Derivative assets: Interest rate swaps 7,154 — 7,154 — Total asset recurring fair value measurements $ 1,486,754 $ 75,989 $ 1,410,765 $ — Derivative liabilities: Interest rate swaps $ 85 $ — $ 85 $ — Total liability recurring fair value measurements $ 85 $ — $ 85 $ — Nonrecurring fair value measurements Foreclosed assets $ 388 $ — $ — $ 388 Impaired loans (2) 9,693 — — 9,693 Total asset nonrecurring fair value measurements $ 10,081 $ — $ — $ 10,081 (1) All mortgage-backed securities are issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. (2) Impaired loans represent collateral-dependent loans with a specific valuation 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, financial liabilities, and unrecognized financial instruments measured on a nonrecurring basis at both their respective carrying amounts and estimated fair value (in thousands): Estimated Fair Value March 31, 2017 Carrying Total Level 1 Level 2 Level 3 Financial Assets: Cash and cash equivalents $ 246,994 $ 246,994 $ 246,994 $ — $ — Investment Securities: Held to maturity, at carrying value 421,133 427,288 — 427,288 — Mortgage-backed Securities: Held to maturity, at carrying value 508,660 513,121 — 513,121 — FHLB stock, at cost, and other investments 66,747 66,747 — 66,747 — Loans, net of allowance for loan losses 2,520,433 2,601,382 — — 2,601,382 Loans held for sale 5,303 5,303 — 5,303 — Financial Liabilities: Deposits $ 3,705,296 $ 3,701,697 $ — $ 3,701,697 $ — Federal funds purchased and repurchase agreements 7,814 7,814 — 7,814 — FHLB advances 1,205,856 1,206,415 — 1,206,415 — Subordinated notes, net of unamortized debt issuance costs 98,133 100,561 — 100,561 — Long-term debt , net of unamortized debt issuance costs 60,237 45,572 — 45,572 — Estimated Fair Value December 31, 2016 Carrying Total Level 1 Level 2 Level 3 Financial Assets: Cash and cash equivalents $ 169,654 $ 169,654 $ 169,654 $ — $ — Investment Securities: Held to maturity, at carrying value 425,810 429,912 — 429,912 — Mortgage-backed Securities: Held to maturity, at carrying value 511,677 514,370 — 514,370 — FHLB stock, at cost, and other investments 66,592 66,592 — 66,592 — Loans, net of allowance for loan losses 2,538,626 2,630,009 — — 2,630,009 Loans held for sale 7,641 7,641 — 7,641 — Financial Liabilities: Deposits $ 3,533,076 $ 3,293,352 $ — $ 3,293,352 $ — Federal funds purchased and repurchase agreements 7,097 7,097 — 7,097 — FHLB advances 1,309,646 1,331,517 — 1,331,517 — Subordinated notes, net of unamortized debt issuance costs 98,100 101,627 — 101,627 — Long-term debt , net of unamortized debt issuance costs 60,236 45,147 — 45,147 —

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	The income tax expense included in the accompanying statements of income consists of the following (in thousands): Three Months Ended 2017 2016 Current income tax expense $ 3,027 $ 3,785 Deferred income tax (benefit) expense (19 ) (812 ) Income tax expense $ 3,008 $ 2,973

Off-Balance-Sheet Arrangement30

Off-Balance-Sheet Arrangements, Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of unused commitments	Financial instruments with off-balance-sheet risk were as follows (in thousands): At At Unused commitments: Commitments to extend credit $ 666,207 $ 665,663 Standby letters of credit 8,612 9,075 Total $ 674,819 $ 674,738

Summary of Significant Accoun31

Summary of Significant Accounting and Reporting Policies - Reclassifications (Details) - Adjustments for New Accounting Pronouncement [Member]	3 Months Ended
	Mar. 31, 2017USD ($)$ / shares
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax effects related to settlements of share-based payment awards reported in earnings as reduction of income tax expense | $	$ (126,000)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Diluted Earnings Per Share | $ / shares	$ (0.01)

Earnings Per Share - Earnings

Earnings Per Share - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Basic and Diluted Earnings:
Net income	$ 14,989	$ 13,516
Basic weighted-average shares outstanding	28,569	26,449
Add: Stock awards (in shares)	208	70
Diluted weighted-average shares outstanding	28,777	26,519
Basic Earnings Per Share:
Earnings per common share - basic (in dollars per share)	$ 0.52	$ 0.51
Diluted Earnings Per Share:
Earnings per common share - diluted (in dollars per share)	$ 0.52	$ 0.51
Antidilutive securities from non-qualified stock options excluded from calculating earnings
Number of antidilutive options (in shares)	52	112

Accumulated Other Comprehensi33

Accumulated Other Comprehensive Income (Loss) - Accumulated Other Comprehensive Income, Changes In (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
AOCI Attributable to Parent, Net of Tax
Beginning Balance		$ 518,274	$ 444,062
Other comprehensive (loss) income before reclassifications		5,078	25,143
Reclassified from accumulated other comprehensive income		925	(1,620)
Income tax benefit (expense)		(2,101)	(8,233)
Net current-period other comprehensive income (loss), net of tax		3,902	15,290
Ending Balance		531,466	457,576
Unrealized Gains (Losses) on Securities
AOCI Attributable to Parent, Net of Tax
Beginning Balance		(23,708)	(239)
Other comprehensive (loss) income before reclassifications		4,885	27,744
Reclassified from accumulated other comprehensive income		166	(2,384)
Income tax benefit (expense)		(1,768)	(8,876)
Net current-period other comprehensive income (loss), net of tax		3,283	16,484
Ending Balance		(20,425)	16,245
Unrealized Gains (Losses) on Derivatives
AOCI Attributable to Parent, Net of Tax
Beginning Balance		4,595	0
Other comprehensive (loss) income before reclassifications		193	(2,601)
Reclassified from accumulated other comprehensive income		370	357
Income tax benefit (expense)		(197)	785
Net current-period other comprehensive income (loss), net of tax		366	(1,459)
Ending Balance		4,961	(1,459)
Net Prior Service (Cost) Credit
AOCI Attributable to Parent, Net of Tax
Beginning Balance		(133)	(44)
Other comprehensive (loss) income before reclassifications		0	0
Reclassified from accumulated other comprehensive income	[1]	(2)	(4)
Income tax benefit (expense)		1	1
Net current-period other comprehensive income (loss), net of tax		(1)	(3)
Ending Balance		(134)	(47)
Net Gain (Loss)
AOCI Attributable to Parent, Net of Tax
Beginning Balance		(19,247)	(18,400)
Other comprehensive (loss) income before reclassifications		0	0
Reclassified from accumulated other comprehensive income	[1]	391	411
Income tax benefit (expense)		(137)	(143)
Net current-period other comprehensive income (loss), net of tax		254	268
Ending Balance		(18,993)	(18,132)
Total
AOCI Attributable to Parent, Net of Tax
Beginning Balance		(38,493)	(18,683)
Ending Balance		$ (34,591)	$ (3,393)
[1]	These accumulated other comprehensive income components are included in the computation of net periodic pension cost (income) presented in “Note 7 - Employee Benefit Plans.”

Accumulated Other Comprehensi34

Accumulated Other Comprehensive Income (Loss) - Reclassifications out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of unrealized losses		$ 488	$ 57
Tax benefit (expense)		(3,008)	(2,973)
Amortization of unrealized gains on terminated interest rate swap derivatives		17,997	16,489
Amortization of pension plan		(925)	1,620
Total reclassifications for the period, net of tax		(601)	1,053
Unrealized gains (losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of pension plan		(166)	2,384
Realized net loss on interest rate swap derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of pension plan		(370)	(357)
Net actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of pension plan	[1]	(391)	(411)
Prior service credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of pension plan	[1]	2	4
Amortization of pension plan
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of pension plan		(389)	(407)
Tax benefit		136	142
Total reclassifications for the period, net of tax		(253)	(265)
Unrealized losses on securities transferred to held to maturity | Reclassification out of accumulated other comprehensive income | Unrealized gains (losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of unrealized losses	[2]	(488)	(57)
Tax benefit (expense)		171	20
Net of tax		(317)	(37)
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)		(113)	(854)
Net of tax		209	1,587
Realized net gain on sale of securities	[3]	322	2,441
Interest rate swap derivatives | Reclassification out of accumulated other comprehensive income | Realized net loss on interest rate swap derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax benefit (expense)		133	125
Net of tax		(246)	(232)
Realized net loss on interest rate swap derivatives	[4]	(379)	(357)
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)		(3)	0
Net of tax		6	0
Amortization of unrealized gains on terminated interest rate swap derivatives	[4]	$ 9	$ 0
[1]	These accumulated other comprehensive income components are included in the computation of net periodic pension cost (income) presented in “Note 7 - Employee Benefit Plans.”
[2]	Included in interest income on the consolidated statements of income.
[3]	Listed as net gain on sale of securities available for sale on the consolidated statements of income.
[4]	Included in interest expense for long-term obligations on the consolidated statements of income.

Securities - Schedule of Debt

Securities - Schedule of Debt and Equity Securities Components (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
AVAILABLE FOR SALE
Amortized cost		$ 1,457,284	$ 1,497,404
Gross unrealized gains, in OCI		10,828	10,916
Gross unrealized losses, in OCI		24,069	28,720
Estimated fair value		1,444,043	1,479,600
HELD TO MATURITY
Amortized cost		947,974	956,156
Gross unrealized gains, in OCI		4,656	5,054
Gross unrealized losses, in OCI		22,837	23,723
Carrying value		929,793	937,487
Gross unrealized gains, not in OCI		15,390	13,501
Gross unrealized losses, not in OCI		4,774	6,706
Estimated fair value		940,409	944,282
U.S. Treasury
AVAILABLE FOR SALE
Amortized cost		62,015	74,016
Gross unrealized gains, in OCI		0	0
Gross unrealized losses, in OCI		2,801	3,947
Estimated fair value		59,214	70,069
State and Political Subdivisions
AVAILABLE FOR SALE
Amortized cost		328,395	394,050
Gross unrealized gains, in OCI		3,227	3,217
Gross unrealized losses, in OCI		10,775	12,070
Estimated fair value		320,847	385,197
HELD TO MATURITY
Amortized cost		430,350	435,080
Gross unrealized gains, in OCI		3,631	3,987
Gross unrealized losses, in OCI		12,848	13,257
Carrying value		421,133	425,810
Gross unrealized gains, not in OCI		8,902	7,595
Gross unrealized losses, not in OCI		2,747	3,493
Estimated fair value		427,288	429,912
Other Stocks and Bonds
AVAILABLE FOR SALE
Amortized cost		6,574	6,587
Gross unrealized gains, in OCI		84	64
Gross unrealized losses, in OCI		0	0
Estimated fair value		6,658	6,651
Other Equity Securities
AVAILABLE FOR SALE
Amortized cost		6,036	6,039
Gross unrealized gains, in OCI		0	0
Gross unrealized losses, in OCI		116	119
Estimated fair value		5,920	5,920
Residential
AVAILABLE FOR SALE
Amortized cost	[1]	685,934	630,603
Gross unrealized gains, in OCI	[1]	6,621	6,434
Gross unrealized losses, in OCI	[1]	7,893	9,529
Estimated fair value	[1]	684,662	627,508
HELD TO MATURITY
Amortized cost	[1]	137,693	142,060
Gross unrealized gains, in OCI	[1]	0	0
Gross unrealized losses, in OCI	[1]	5,478	5,748
Carrying value	[1]	132,215	136,312
Gross unrealized gains, not in OCI	[1]	1,536	1,534
Gross unrealized losses, not in OCI	[1]	370	950
Estimated fair value	[1]	133,381	136,896
Commercial
AVAILABLE FOR SALE
Amortized cost	[1]	368,330	386,109
Gross unrealized gains, in OCI	[1]	896	1,201
Gross unrealized losses, in OCI	[1]	2,484	3,055
Estimated fair value	[1]	366,742	384,255
HELD TO MATURITY
Amortized cost	[1]	379,931	379,016
Gross unrealized gains, in OCI	[1]	1,025	1,067
Gross unrealized losses, in OCI	[1]	4,511	4,718
Carrying value	[1]	376,445	375,365
Gross unrealized gains, not in OCI	[1]	4,952	4,372
Gross unrealized losses, not in OCI	[1]	1,657	2,263
Estimated fair value	[1]	$ 379,740	$ 377,474
[1]	All mortgage-backed securities issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Securities - Unrealized Loss o

Securities - Unrealized Loss on Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	$ 884,812	$ 955,799
More than 12 months, fair value	3,230	7,086
Total fair value	888,042	962,885
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, unrealized loss	24,062	28,681
More than 12 months, unrealized loss	7	39
Total unrealized loss	24,069	28,720
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	327,477	473,817
More than 12 months, fair value	25,976	29,427
Total fair value	353,453	503,244
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Losses [Abstract]
Less than 12 months, unrealized loss	3,399	5,403
More than 12 months, unrealized loss	1,375	1,303
Total unrealized loss	4,774	6,706
U.S. Treasury
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	59,214	70,069
More than 12 months, fair value	0	0
Total fair value	59,214	70,069
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, unrealized loss	2,801	3,947
More than 12 months, unrealized loss	0	0
Total unrealized loss	2,801	3,947
State and Political Subdivisions
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	209,637	264,485
More than 12 months, fair value	886	887
Total fair value	210,523	265,372
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, unrealized loss	10,774	12,069
More than 12 months, unrealized loss	1	1
Total unrealized loss	10,775	12,070
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	99,422	179,939
More than 12 months, fair value	25,976	29,427
Total fair value	125,398	209,366
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Losses [Abstract]
Less than 12 months, unrealized loss	1,372	2,190
More than 12 months, unrealized loss	1,375	1,303
Total unrealized loss	2,747	3,493
Other Equity Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	5,920	5,920
More than 12 months, fair value	0	0
Total fair value	5,920	5,920
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, unrealized loss	116	119
More than 12 months, unrealized loss	0	0
Total unrealized loss	116	119
Residential
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	361,710	369,903
More than 12 months, fair value	2,344	6,199
Total fair value	364,054	376,102
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, unrealized loss	7,887	9,491
More than 12 months, unrealized loss	6	38
Total unrealized loss	7,893	9,529
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	55,917	107,024
More than 12 months, fair value	0	0
Total fair value	55,917	107,024
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Losses [Abstract]
Less than 12 months, unrealized loss	370	950
More than 12 months, unrealized loss	0	0
Total unrealized loss	370	950
Commercial
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	248,331	245,422
More than 12 months, fair value	0	0
Total fair value	248,331	245,422
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, unrealized loss	2,484	3,055
More than 12 months, unrealized loss	0	0
Total unrealized loss	2,484	3,055
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	172,138	186,854
More than 12 months, fair value	0	0
Total fair value	172,138	186,854
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Losses [Abstract]
Less than 12 months, unrealized loss	1,657	2,263
More than 12 months, unrealized loss	0	0
Total unrealized loss	$ 1,657	$ 2,263

Securities - Interest Income o

Securities - Interest Income on Securities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract]
U.S. Treasury	$ 315	$ 127
State and Political Subdivisions	6,554	5,355
Other Stocks and Bonds	34	58
Other Equity Securities	28	29
Mortgage-backed Securities	10,045	9,391
Total interest income on securities	$ 16,976	$ 14,960

Securities - Amortized Cost an

Securities - Amortized Cost and Estimated Fair Value of Investments in Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Amortized Cost
Due in one year or less	$ 6,694
Due after one year through five years	23,638
Due after five years through ten years	96,416
Due after ten years	270,236
Total available-for-sale investment securities	396,984
Mortgage-backed Securities and Other Equity Securities:	1,060,300
Total	1,457,284
Fair Value
Due in one year or less	6,851
Due after one year through five years	24,655
Due after five years through ten years	93,961
Due after ten years	261,252
Total available-for-sale investment securities	386,719
Mortgage-backed Securities and Other Equity Securities:	1,057,324
Total	1,444,043	$ 1,479,600
Carrying Value
Due in one year or less	10,119
Due after one year through five years	39,539
Due after five years through ten years	101,274
Due after ten years	270,201
Total held-to-maturity investment securities	421,133
Mortgage-backed securities	508,660
Carrying value	929,793	$ 937,487
Fair Value
Due in one year or less	10,181
Due after one year through five years	39,935
Due after five years through ten years	101,898
Due after ten years	275,274
Total held-to-maturity investment securities	427,288
Mortgage-backed securities	513,121
Total	$ 940,409

Securities - Narrative (Detail

Securities - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Balance at beginning of period	$ 17,911,000	$ 19,736,000	$ 19,736,000
Securities Transferred From Available for Sale to Held to Maturity	0		157,100,000
Unrealized loss on securities transferred from AFS to HTM			(10,200,000)
Net unrealized gain on securities transferred from AFS to HTM			(6,656,000)
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Net realized gain on AFS securities	322,000	2,400,000
Realized gains	1,700,000	2,600,000
Realized losses	1,400,000	202,000
Held-to-maturity Securities, Other Disclosure Items [Abstract]
Sales from HTM portfolio	0	$ 0
Carrying value of investment securities pledged as collateral	$ 1,290,000,000		$ 1,500,000,000

Loans and Allowance for Proba40

Loans and Allowance for Probable Loan Losses - Loans by Portfolio Segment (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Loans and Leases Receivable Disclosure [Abstract]
Total ending loan balance	[1]	$ 2,538,918	$ 2,556,537
Less: Allowance for Loan Losses (2)	[1]	18,485	17,911
Net Loans		2,520,433	2,538,626
Construction Real Estate Loans
Loans and Leases Receivable Disclosure [Abstract]
Total ending loan balance		362,367	380,175
1-4 Family Residential Real Estate Loans
Loans and Leases Receivable Disclosure [Abstract]
Total ending loan balance		622,881	637,239
Commercial Real Estate Loans
Loans and Leases Receivable Disclosure [Abstract]
Total ending loan balance		974,307	945,978
Commercial Loans
Loans and Leases Receivable Disclosure [Abstract]
Total ending loan balance		176,908	177,265
Municipal Loans
Loans and Leases Receivable Disclosure [Abstract]
Total ending loan balance		297,417	298,583
Loans to Individuals
Loans and Leases Receivable Disclosure [Abstract]
Total ending loan balance		105,038	117,297
OmniAmerican Bancorp, Inc.
Loans and Financing Receivable [Line Items]
Loans acquired carrying amount		324,900	372,400
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment, PCI Loans		$ 3	$ 3
[1]	Includes approximately $324.9 million and $372.4 million of loans acquired with the Omni acquisition as of March 31, 2017 and December 31, 2016, respectively.

Loans and Allowance for Proba41

Loans and Allowance for Probable Loan Losses - Allowance for Loan Losses Activity by Portfolio Segment (Details) - USD ($)		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period		$ 17,911,000	$ 19,736,000
Provision (reversal) for loan losses	[1]	1,098,000	2,316,000
Loans charged off		(1,054,000)	(1,140,000)
Recoveries of loans charged off		530,000	887,000
Balance at end of period		18,485,000	21,799,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Provision for loan losses		1,098,000	2,316,000
Provision for PCI Loans		0	296,000
Construction Real Estate Loans
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period		4,147,000	4,350,000
Provision (reversal) for loan losses		(722,000)	(42,000)
Loans charged off		(18,000)	0
Recoveries of loans charged off		0	269,000
Balance at end of period		3,407,000	4,577,000
1-4 Family Residential Real Estate Loans
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period		2,665,000	2,595,000
Provision (reversal) for loan losses		(62,000)	(551,000)
Loans charged off		(287,000)	(19,000)
Recoveries of loans charged off		1,000	130,000
Balance at end of period		2,317,000	2,155,000
Commercial Real Estate Loans
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period		7,204,000	4,577,000
Provision (reversal) for loan losses		1,577,000	(116,000)
Loans charged off		0	0
Recoveries of loans charged off		6,000	6,000
Balance at end of period		8,787,000	4,467,000
Commercial Loans
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period		2,263,000	6,596,000
Provision (reversal) for loan losses		(112,000)	2,620,000
Loans charged off		(3,000)	(273,000)
Recoveries of loans charged off		111,000	21,000
Balance at end of period		2,259,000	8,964,000
Municipal Loans
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period		750,000	725,000
Provision (reversal) for loan losses		(4,000)	(5,000)
Loans charged off		0	0
Recoveries of loans charged off		0	0
Balance at end of period		746,000	720,000
Loans to Individuals
Allowances for Loan Losses [Roll Forward]
Balance at beginning of period		882,000	893,000
Provision (reversal) for loan losses		421,000	410,000
Loans charged off		(746,000)	(848,000)
Recoveries of loans charged off		412,000	461,000
Balance at end of period		$ 969,000	$ 916,000
[1]	Of the $1.1 million and $2.3 million recorded in provision for loan losses for the three months ended March 31, 2017 and March 31, 2016, none related to provision expense on PCI loans as of March 31, 2017 and $296,000 related to provision expense on PCI loans as of March 31, 2016.

Loans and Allowance for Proba42

Loans and Allowance for Probable Loan Losses - Allowance Balance, by Impairment Method (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Schedule of Allowance For Loan Losses, Allowance Balance, by Impairment Method [Line Items]
Ending balance - individually evaluated for impairment	[1]	$ 1,122	$ 1,086
Ending balance - collectively evaluated for impairment		17,363	16,825
Balance at end of period		18,485	17,911	$ 21,799	$ 19,736
Construction Real Estate Loans
Schedule of Allowance For Loan Losses, Allowance Balance, by Impairment Method [Line Items]
Ending balance - individually evaluated for impairment	[1]	10	13
Ending balance - collectively evaluated for impairment		3,397	4,134
Balance at end of period		3,407	4,147	4,577	4,350
1-4 Family Residential Real Estate Loans
Schedule of Allowance For Loan Losses, Allowance Balance, by Impairment Method [Line Items]
Ending balance - individually evaluated for impairment	[1]	13	16
Ending balance - collectively evaluated for impairment		2,304	2,649
Balance at end of period		2,317	2,665	2,155	2,595
Commercial Real Estate Loans
Schedule of Allowance For Loan Losses, Allowance Balance, by Impairment Method [Line Items]
Ending balance - individually evaluated for impairment	[1]	15	17
Ending balance - collectively evaluated for impairment		8,772	7,187
Balance at end of period		8,787	7,204	4,467	4,577
Commercial Loans
Schedule of Allowance For Loan Losses, Allowance Balance, by Impairment Method [Line Items]
Ending balance - individually evaluated for impairment	[1]	982	923
Ending balance - collectively evaluated for impairment		1,277	1,340
Balance at end of period		2,259	2,263	8,964	6,596
Municipal Loans
Schedule of Allowance For Loan Losses, Allowance Balance, by Impairment Method [Line Items]
Ending balance - individually evaluated for impairment	[1]	11	11
Ending balance - collectively evaluated for impairment		735	739
Balance at end of period		746	750	720	725
Loans to Individuals
Schedule of Allowance For Loan Losses, Allowance Balance, by Impairment Method [Line Items]
Ending balance - individually evaluated for impairment	[1]	91	106
Ending balance - collectively evaluated for impairment		878	776
Balance at end of period		969	882	$ 916	$ 893
OmniAmerican Bancorp, Inc.
Schedule of Allowance For Loan Losses, Allowance Balance, by Impairment Method [Line Items]
Allowance for credit losses, individually evaluated for impairment, PCI loans		$ 3	$ 3
[1]	There was approximately $3,000 of allowance for loan losses associated with PCI loans as of March 31, 2017 and December 31, 2016.

Loans and Allowance for Proba43

Loans and Allowance for Probable Loan Losses - Allowance for Loan Losses, Loan Portfolio, by Impairment Method (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Schedule of Allowance For Loan Losses, Loan Balance, by Impairment Method [Line Items]
Loans individually evaluated for impairment		$ 9,508	$ 10,009
Loans collectively evaluated for impairment		2,520,653	2,537,331
Purchased credit impaired loans		8,757	9,197
Total ending loan balance	[1]	2,538,918	2,556,537
Construction Real Estate Loans
Schedule of Allowance For Loan Losses, Loan Balance, by Impairment Method [Line Items]
Loans individually evaluated for impairment		430	480
Loans collectively evaluated for impairment		361,784	379,526
Purchased credit impaired loans		153	169
Total ending loan balance		362,367	380,175
1-4 Family Residential Real Estate Loans
Schedule of Allowance For Loan Losses, Loan Balance, by Impairment Method [Line Items]
Loans individually evaluated for impairment		1,672	1,693
Loans collectively evaluated for impairment		615,628	629,893
Purchased credit impaired loans		5,581	5,653
Total ending loan balance		622,881	637,239
Commercial Real Estate Loans
Schedule of Allowance For Loan Losses, Loan Balance, by Impairment Method [Line Items]
Loans individually evaluated for impairment		1,081	1,184
Loans collectively evaluated for impairment		971,593	942,818
Purchased credit impaired loans		1,633	1,976
Total ending loan balance		974,307	945,978
Commercial Loans
Schedule of Allowance For Loan Losses, Loan Balance, by Impairment Method [Line Items]
Loans individually evaluated for impairment		5,529	5,840
Loans collectively evaluated for impairment		170,090	170,159
Purchased credit impaired loans		1,289	1,266
Total ending loan balance		176,908	177,265
Municipal Loans
Schedule of Allowance For Loan Losses, Loan Balance, by Impairment Method [Line Items]
Loans individually evaluated for impairment		571	571
Loans collectively evaluated for impairment		296,846	298,012
Purchased credit impaired loans		0	0
Total ending loan balance		297,417	298,583
Loans to Individuals
Schedule of Allowance For Loan Losses, Loan Balance, by Impairment Method [Line Items]
Loans individually evaluated for impairment		225	241
Loans collectively evaluated for impairment		104,712	116,923
Purchased credit impaired loans		101	133
Total ending loan balance		$ 105,038	$ 117,297
[1]	Includes approximately $324.9 million and $372.4 million of loans acquired with the Omni acquisition as of March 31, 2017 and December 31, 2016, respectively.

Loans and Allowance for Proba44

Loans and Allowance for Probable Loan Losses - Loans by Credit Quality Indicator (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[1]	$ 2,538,918	$ 2,556,537
Purchased credit impaired loans		8,757	9,197
Pass
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		2,462,781	2,464,338
Pass Watch
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	4,472	19,028
Purchased credit impaired loans		5	5
Special Mention
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	14,165	20,251
Purchased credit impaired loans		507	511
Substandard
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	56,519	51,303
Purchased credit impaired loans		1,100	1,500
Doubtful
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	981	1,617
Purchased credit impaired loans		28	28
Construction Real Estate Loans
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		362,367	380,175
Purchased credit impaired loans		153	169
Construction Real Estate Loans | Pass
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		358,837	374,443
Construction Real Estate Loans | Pass Watch
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	33	34
Construction Real Estate Loans | Special Mention
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	159	571
Construction Real Estate Loans | Substandard
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	3,320	5,108
Construction Real Estate Loans | Doubtful
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	18	19
1-4 Family Residential Real Estate Loans
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		622,881	637,239
Purchased credit impaired loans		5,581	5,653
1-4 Family Residential Real Estate Loans | Pass
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		618,810	632,937
1-4 Family Residential Real Estate Loans | Pass Watch
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	14	68
1-4 Family Residential Real Estate Loans | Special Mention
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	0	0
1-4 Family Residential Real Estate Loans | Substandard
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	3,626	3,380
1-4 Family Residential Real Estate Loans | Doubtful
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	431	854
Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		974,307	945,978
Purchased credit impaired loans		1,633	1,976
Commercial Real Estate Loans | Pass
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		922,584	885,049
Commercial Real Estate Loans | Pass Watch
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	3,258	17,739
Commercial Real Estate Loans | Special Mention
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	8,657	10,587
Commercial Real Estate Loans | Substandard
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	39,808	32,603
Commercial Real Estate Loans | Doubtful
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	0	0
Commercial Loans
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		176,908	177,265
Purchased credit impaired loans		1,289	1,266
Commercial Loans | Pass
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		162,780	158,943
Commercial Loans | Pass Watch
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	1,167	1,187
Commercial Loans | Special Mention
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	4,372	8,086
Commercial Loans | Substandard
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	8,544	9,012
Commercial Loans | Doubtful
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	45	37
Municipal Loans
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		297,417	298,583
Purchased credit impaired loans		0	0
Municipal Loans | Pass
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		295,896	297,014
Municipal Loans | Pass Watch
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	0	0
Municipal Loans | Special Mention
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	950	998
Municipal Loans | Substandard
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	571	571
Municipal Loans | Doubtful
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	0	0
Loans to Individuals
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		105,038	117,297
Purchased credit impaired loans		101	133
Loans to Individuals | Pass
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans		103,874	115,952
Loans to Individuals | Pass Watch
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	0	0
Loans to Individuals | Special Mention
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	27	9
Loans to Individuals | Substandard
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	650	629
Loans to Individuals | Doubtful
Financing Receivable, Recorded Investment, Credit Quality Indicator [Abstract]
Loans	[2]	$ 487	$ 707
[1]	Includes approximately $324.9 million and $372.4 million of loans acquired with the Omni acquisition as of March 31, 2017 and December 31, 2016, respectively.
[2]	Includes PCI loans comprised of $5,000 pass watch, $507,000 special mention, $1.1 million substandard and $28,000 doubtful as of March 31, 2017. Includes PCI loans comprised of $5,000 pass watch, $511,000 special mention, $1.5 million substandard and $28,000 doubtful as of December 31, 2016.

Loans and Allowance for Proba45

Loans and Allowance for Probable Loan Losses - Nonperforming Assets by Asset Class (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Nonperforming Assets by Asset Class [Abstract]
Nonaccrual loans	[1]	$ 7,261	$ 8,280
Accruing loans past due more than 90 days		1	6
Restructured loans	[2]	6,424	6,431
Other real estate owned		367	339
Repossessed assets		26	49
Total Nonperforming Assets		14,079	15,105
Purchase Credit Impaired Loans Restructured		$ 3,000	$ 3,100
[1]	Excludes PCI loans measured at fair value at acquisition.
[2]	Includes $3.0 million and $3.1 million in PCI loans restructured as of March 31, 2017 and December 31, 2016, respectively.

Loans and Allowance for Proba46

Loans and Allowance for Probable Loan Losses - Nonaccrual by Class of Loans (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans	[1]	$ 7,261	$ 8,280
Construction Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		55	105
1-4 Family Residential Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		673	1,067
Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		723	808
Commercial Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		5,127	5,477
Loans to Individuals
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		$ 683	$ 823
[1]	Excludes PCI loans measured at fair value at acquisition.

Loans and Allowance for Proba47

Loans and Allowance for Probable Loan Losses - Impaired Loans by Class of Loan (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Impaired Financing Receivable, Recorded Investment [Abstract]
Unpaid Contractual Principal Balance	[1]	$ 13,021	$ 13,560
Recorded Investment	[1]	12,550	13,071
Related Allowance for Loan Losses		1,122	1,086
PCI loans that experienced deterioration in credit quality subsequent to acquisition		3,000	3,100
Construction Real Estate Loans
Impaired Financing Receivable, Recorded Investment [Abstract]
Unpaid Contractual Principal Balance		437	486
Recorded Investment		430	480
Related Allowance for Loan Losses		10	13
1-4 Family Residential Real Estate Loans
Impaired Financing Receivable, Recorded Investment [Abstract]
Unpaid Contractual Principal Balance		4,429	4,487
Recorded Investment		4,221	4,264
Related Allowance for Loan Losses		13	16
Commercial Real Estate Loans
Impaired Financing Receivable, Recorded Investment [Abstract]
Unpaid Contractual Principal Balance		1,530	1,631
Recorded Investment		1,465	1,574
Related Allowance for Loan Losses		15	17
Commercial Loans
Impaired Financing Receivable, Recorded Investment [Abstract]
Unpaid Contractual Principal Balance		5,798	6,108
Recorded Investment		5,638	5,941
Related Allowance for Loan Losses		982	923
Municipal Loans
Impaired Financing Receivable, Recorded Investment [Abstract]
Unpaid Contractual Principal Balance		571	571
Recorded Investment		571	571
Related Allowance for Loan Losses		11	11
Loans to Individuals
Impaired Financing Receivable, Recorded Investment [Abstract]
Unpaid Contractual Principal Balance		256	277
Recorded Investment		225	241
Related Allowance for Loan Losses		$ 91	$ 106
[1]	Includes $3.0 million and $3.1 million of PCI loans that experienced deterioration in credit quality subsequent to the acquisition date as of March 31, 2017 and December 31, 2016, respectively.

Loans and Allowance for Proba48

Loans and Allowance for Probable Loan Losses - Aging of Past Due Loans by Class of Loan (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		$ 16,897	$ 15,735
Current	[1]	2,522,021	2,540,802
Total ending loan balance	[2]	2,538,918	2,556,537
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		12,465	9,658
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,026	1,593
Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		3,406	4,484
Construction Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		2,445	1,067
Current	[1]	359,922	379,108
Total ending loan balance		362,367	380,175
Construction Real Estate Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		2,423	917
Construction Real Estate Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		0	64
Construction Real Estate Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		22	86
1-4 Family Residential Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		5,740	7,580
Current	[1]	617,141	629,659
Total ending loan balance		622,881	637,239
1-4 Family Residential Real Estate Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		5,330	6,225
1-4 Family Residential Real Estate Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		81	755
1-4 Family Residential Real Estate Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		329	600
Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,411	378
Current	[1]	972,896	945,600
Total ending loan balance		974,307	945,978
Commercial Real Estate Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,179	70
Commercial Real Estate Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		151	154
Commercial Real Estate Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		81	154
Commercial Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		5,413	4,542
Current	[1]	171,495	172,723
Total ending loan balance		176,908	177,265
Commercial Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		2,020	783
Commercial Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		686	300
Commercial Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		2,707	3,459
Municipal Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		663	113
Current	[1]	296,754	298,470
Total ending loan balance		297,417	298,583
Municipal Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		663	113
Municipal Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		0	0
Municipal Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		0	0
Loans to Individuals
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,225	2,055
Current	[1]	103,813	115,242
Total ending loan balance		105,038	117,297
Loans to Individuals | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		850	1,550
Loans to Individuals | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		108	320
Loans to Individuals | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		$ 267	$ 185
[1]	Includes PCI loans measured at fair value at acquisition.
[2]	Includes approximately $324.9 million and $372.4 million of loans acquired with the Omni acquisition as of March 31, 2017 and December 31, 2016, respectively.

Loans and Allowance for Proba49

Loans and Allowance for Probable Loan Losses - Interest Income on Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Impaired Financing Receivable, Average Recorded Investment and Interest Income on Impaired Loans [Abstract]
Average recorded investment	$ 12,874	$ 30,366
Interest income recognized	109	219
Construction Real Estate Loans
Impaired Financing Receivable, Average Recorded Investment and Interest Income on Impaired Loans [Abstract]
Average recorded investment	467	454
Interest income recognized	4	6
1-4 Family Residential Real Estate Loans
Impaired Financing Receivable, Average Recorded Investment and Interest Income on Impaired Loans [Abstract]
Average recorded investment	4,262	1,865
Interest income recognized	57	14
Commercial Real Estate Loans
Impaired Financing Receivable, Average Recorded Investment and Interest Income on Impaired Loans [Abstract]
Average recorded investment	1,522	5,488
Interest income recognized	19	21
Commercial Loans
Impaired Financing Receivable, Average Recorded Investment and Interest Income on Impaired Loans [Abstract]
Average recorded investment	5,787	21,675
Interest income recognized	19	167
Municipal Loans
Impaired Financing Receivable, Average Recorded Investment and Interest Income on Impaired Loans [Abstract]
Average recorded investment	571	637
Interest income recognized	8	9
Loans to Individuals
Impaired Financing Receivable, Average Recorded Investment and Interest Income on Impaired Loans [Abstract]
Average recorded investment	265	247
Interest income recognized	$ 2	$ 2

Loans and Allowance for Proba50

Loans and Allowance for Probable Loan Losses - Troubled Debt Restructurings (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)contract	Mar. 31, 2016USD ($)contract
Troubled Debt Restructuring [Abstract]
Extend Amortization Period	$ 52	$ 3,848
Interest Rate Reductions	0	0
Combination	12	0
Total Modifications	$ 64	$ 3,848
Number of Loans | contract	3	6
Construction Real Estate Loans
Troubled Debt Restructuring [Abstract]
Extend Amortization Period		$ 554
Interest Rate Reductions		0
Combination		0
Total Modifications		$ 554
Number of Loans | contract		1
Commercial Real Estate Loans
Troubled Debt Restructuring [Abstract]
Extend Amortization Period		$ 2,118
Interest Rate Reductions		0
Combination		0
Total Modifications		$ 2,118
Number of Loans | contract		1
Commercial Loans
Troubled Debt Restructuring [Abstract]
Extend Amortization Period	$ 47	$ 1,176
Interest Rate Reductions	0	0
Combination	0	0
Total Modifications	$ 47	$ 1,176
Number of Loans | contract	1	4
Loans to Individuals
Troubled Debt Restructuring [Abstract]
Extend Amortization Period	$ 5
Interest Rate Reductions	0
Combination	12
Total Modifications	$ 17
Number of Loans | contract	2

Loans and Allowance for Proba51

Loans and Allowance for Probable Loan Losses - Purchased Credit Impaired (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Purchased Credit Impaired [Abstract]
Outstanding principal balance	$ 9,924		$ 10,612
Purchased credit impaired loans	8,757		$ 9,197
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	2,480	$ 2,493
Reclassifications (to) from nonaccretable discount	1,819	443
Accretion	(296)	(594)
Balance at end of period	$ 4,003	$ 2,342

Loans and Allowance for Proba52

Loans and Allowance for Probable Loan Losses - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Owner and nonowner-occupied real estate	$ 902,900,000
Loans secured by multi-family properties	67,700,000
Loans secured by farmland	3,700,000
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans transferred to other repossessed assets and real estate through foreclosure	0		$ 28,000
TDRs in defaults		$ 1,400,000
Loans and leases receivable, impaired, commitment to lend	0	$ 0
Minimum
Financing Receivable, Allowance for Credit Losses [Line Items]
Loan review larger dollar loan relationship scope, aggregate debt	500,000
Specifically reserved loans or loan relationships threshold	$ 150,000

Long-term Obligations - Long-t

Long-term Obligations - Long-term Obligations (Details) - USD ($)		3 Months Ended	12 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
Debt Instruments [Abstract]
Subordinated Debt		$ 98,133,000	$ 98,100,000
Long-term debt		60,237,000	60,236,000
Total long-term obligations		411,310,000	601,464,000
FHLB advances		252,940,000	443,128,000
Parent Company
Debt Instruments [Abstract]
Subordinated Debt	[1]	98,133,000	98,100,000
Long-term debt	[2]	60,237,000	60,236,000
Total long-term obligations		$ 158,370,000	158,336,000
Parent Company | 5.50% Subordinated Notes Due 2026, net of unamortized debt issuance costs
Debt Instrument [Line Items]
Maturity date		2,026
Aggregate principal amount of subordinated notes		$ 100,000,000	100,000,000
Unamortized debt issuance costs		$ 1,900,000	1,900,000
Basis spread on variable rate		4.297%
Debt Instruments [Abstract]
Subordinated Debt	[1],[3]	$ 98,133,000	98,100,000
Long-term Debt, Other Disclosures [Abstract]
Subordinated notes, interest rate		5.50%
Debt instrument, description of variable rate basis	[1],[3]	three-month LIBOR plus 429.7 basis points
Parent Company | Southside Statutory Trust III Due 2033, net of unamortized debt issuance costs
Debt Instrument [Line Items]
Maturity date		2,033
Unamortized debt issuance costs		$ 74,000	75,000
Debt Instruments [Abstract]
Long-term debt	[2],[4]	$ 20,545,000	20,544,000
Long-term Debt, Other Disclosures [Abstract]
Debt instrument, description of variable rate basis		three-month LIBOR plus 294 basis points
Adjusted rate of debt		4.08678%
Parent Company | Southside Statutory Trust IV Due 2037
Debt Instrument [Line Items]
Maturity date		2,037
Debt Instruments [Abstract]
Long-term debt	[2],[5]	$ 23,196,000	23,196,000
Long-term Debt, Other Disclosures [Abstract]
Debt instrument, description of variable rate basis		three-month LIBOR plus 130 basis points
Adjusted rate of debt		2.339%
Parent Company | Southside Statutory Trust V Due 2037
Debt Instrument [Line Items]
Maturity date		2,037
Debt Instruments [Abstract]
Long-term debt	[2],[6]	$ 12,887,000	12,887,000
Long-term Debt, Other Disclosures [Abstract]
Debt instrument, description of variable rate basis		three-month LIBOR plus 225 basis points
Adjusted rate of debt		3.38122%
Parent Company | Magnolia Trust Company I Due 2035
Debt Instrument [Line Items]
Maturity date		2,035
Debt Instruments [Abstract]
Long-term debt	[2],[7]	$ 3,609,000	3,609,000
Long-term Debt, Other Disclosures [Abstract]
Debt instrument, description of variable rate basis		three-month LIBOR plus 180 basis points
Adjusted rate of debt		2.85344%
Parent Company | London Interbank Offered Rate (LIBOR) [Member] | Southside Statutory Trust III Due 2033, net of unamortized debt issuance costs
Debt Instrument [Line Items]
Basis spread on variable rate		2.94%
Parent Company | London Interbank Offered Rate (LIBOR) [Member] | Southside Statutory Trust IV Due 2037
Debt Instrument [Line Items]
Basis spread on variable rate		1.30%
Parent Company | London Interbank Offered Rate (LIBOR) [Member] | Southside Statutory Trust V Due 2037
Debt Instrument [Line Items]
Basis spread on variable rate		2.25%
Parent Company | London Interbank Offered Rate (LIBOR) [Member] | Magnolia Trust Company I Due 2035
Debt Instrument [Line Items]
Basis spread on variable rate		1.80%
Subsidiaries
Debt Instruments [Abstract]
Total long-term obligations		$ 252,940,000	443,128,000
Subsidiaries | Federal Home Loan Bank Advances
Debt Instruments [Abstract]
FHLB advances	[8]	$ 252,940,000	$ 443,128,000
Long-term Debt, Other Disclosures [Abstract]
Weighted average cost (as a percent)		1.50%
Minimum | Parent Company | Subordinated Notes
Long-term Debt, Other Disclosures [Abstract]
Long-term debt, remaining maturity		1 year
Variable rate advance agreements | Three-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		(0.25%)
Long-term Debt, Other Disclosures [Abstract]
Debt instrument, description of variable rate basis		three-month LIBOR
[1]	This long-term 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 long-term debt consists of trust preferred securities that qualify under the risk-based capital guidelines as Tier 1 capital, subject to certain limitations.
[3]	This debt carries a fixed rate of 5.50% through September 29, 2021 and thereafter, adjusts quarterly at a rate equal to three-month LIBOR plus 429.7 basis points.
[4]	This debt carries an adjustable rate of 4.08678% through June 29, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 294 basis points.
[5]	This debt carries an adjustable rate of 2.339% through April 29, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 130 basis points.
[6]	This debt carries an adjustable rate of 3.38122% through June 14, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 225 basis points.
[7]	This debt carries an adjustable rate of 2.85344% through May 22, 2017 and adjusts quarterly at a rate equal to three-month LIBOR plus 180 basis points.
[8]	At March 31, 2017, the weighted average cost of these advances was 1.5%. Long-term FHLB advances have maturities ranging from April 2018 through July 2028.

Long-term Obligations - Subord

Long-term Obligations - Subordinated Debt and Long-term Debt Narrative (Details) - Parent Company - USD ($)		3 Months Ended	12 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
5.50% Subordinated Notes Due 2026, net of unamortized debt issuance costs
Debt Instrument [Line Items]
Aggregate principal amount of subordinated notes		$ 100,000,000	$ 100,000,000
Debt instrument, fixed interest rate		5.50%
Debt instrument, description of variable rate basis	[1],[2]	three-month LIBOR plus 429.7 basis points
Unamortized debt issuance costs		$ 1,900,000	1,900,000
Southside Statutory Trust III Due 2033, net of unamortized debt issuance costs
Debt Instrument [Line Items]
Debt instrument, description of variable rate basis		three-month LIBOR plus 294 basis points
Unamortized debt issuance costs		$ 74,000	$ 75,000
[1]	This debt carries a fixed rate of 5.50% through September 29, 2021 and thereafter, adjusts quarterly at a rate equal to three-month LIBOR plus 429.7 basis points.
[2]	This long-term 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.

Long-term Obligations - Intere

Long-term Obligations - Interest Rate Swaps (Details)	3 Months Ended
	Mar. 31, 2017USD ($)agreementcontractRate	Dec. 31, 2016USD ($)
Derivative [Line Items]
Debt instrument, face amount	$ 240,000,000
Variable rate advance agreements
Derivative [Line Items]
Derivative, description of hedged item	various variable rate advance agreements with the FHLB
Debt instrument, face amount	$ 240,000,000	$ 250,000,000
Variable rate advance agreements | Long-term Debt
Derivative [Line Items]
Debt instrument, face amount	$ 60,000,000	$ 230,000,000
Three-month LIBOR | Variable rate advance agreements
Derivative [Line Items]
Number of variable rate advance agreements | agreement	2
Debt instrument, description of variable rate basis	three-month LIBOR
Basis spread on variable rate | Rate	(0.25%)
One-month LIBOR | Variable rate advance agreements
Derivative [Line Items]
Debt instrument, description of variable rate basis	one-month LIBOR
One-month LIBOR | Variable rate advance agreements | Minimum
Derivative [Line Items]
Basis spread on variable rate | Rate	0.17%
One-month LIBOR | Variable rate advance agreements | Maximum
Derivative [Line Items]
Basis spread on variable rate | Rate	0.278%
Interest rate swaps
Derivative [Line Items]
Derivative, instruments terminated | contract	2
Notional value of instruments terminated	$ 40,000,000
Interest rate swaps | Minimum
Derivative [Line Items]
Derivative, Fixed Interest Rate	0.932%
Derivative, Term of Contract	5 years
Interest rate swaps | Maximum
Derivative [Line Items]
Derivative, Fixed Interest Rate	2.345%
Derivative, Term of Contract	10 years

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 358	$ 368
Interest cost	912	917
Expected return on assets	(1,512)	(1,354)
Net loss amortization	344	358
Prior service (credit) cost amortization	(4)	(6)
Special and contractual termination benefits	0	1,520
Net periodic benefit cost (income)	98	1,803
Defined Benefit Pension Plan Acquired
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	0	0
Interest cost	45	53
Expected return on assets	(54)	(67)
Net loss amortization	0	0
Prior service (credit) cost amortization	0	0
Special and contractual termination benefits	0	0
Net periodic benefit cost (income)	(9)	(14)
Restoration Plan
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	51	47
Interest cost	132	135
Expected return on assets	0	0
Net loss amortization	47	53
Prior service (credit) cost amortization	2	2
Special and contractual termination benefits	0	0
Net periodic benefit cost (income)	$ 232	$ 237

Derivative Financial Instrume57

Derivative Financial Instruments and Hedging Activities - Narrative (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Debt instrument, face amount	$ 240,000,000
Derivative Asset, Collateral, Obligation to Return Cash, Offset	7,360,000	$ 7,154,000
Collateral Already Posted, Aggregate Fair Value	408,000
Derivative, Collateral, Obligation to Return Cash	$ 42,000

Derivative Financial Instrume58

Derivative Financial Instruments and Hedging Activities - Schedule Of Derivative Instruments (Details) - USD ($)		Mar. 31, 2017	Dec. 31, 2016
Asset Derivative
Gross derivatives		$ 7,994,000	$ 7,154,000
Offsetting derivative assets		(127,000)	0
Cash collateral received/posted		(7,360,000)	(7,154,000)
Net derivatives included in the consolidated balance sheets	[1]	507,000	0
Liability Derivative
Gross derivatives		626,000	85,000
Offsetting derivative liabilities		(127,000)	0
Cash collateral received/posted		(408,000)	0
Net derivatives included in the consolidated balance sheets	[1]	91,000	85,000
Financial Institution Counterparties
Liability Derivative
Net credit exposure		8,000	0
Financial Institution Counterparties | Designated as Hedging Instrument | Cash Flow Hedging | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Notional Amount	[2]	240,000,000	250,000,000
Asset Derivative
Gross derivatives		7,404,000	7,069,000
Liability Derivative
Gross derivatives		36,000	0
Financial Institution Counterparties | Not Designated as Hedging Instrument | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Notional Amount	[2]	46,196,000	2,182,000
Asset Derivative
Gross derivatives		91,000	85,000
Liability Derivative
Gross derivatives		499,000	0
Customer Counterparties
Liability Derivative
Net credit exposure		499,000	0
Customer Counterparties | Not Designated as Hedging Instrument | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Notional Amount	[2]	46,196,000	2,182,000
Asset Derivative
Gross derivatives		499,000	0
Liability Derivative
Gross derivatives		$ 91,000	$ 85,000
[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 net credit exposure of $8,000 related to interest rate swaps with financial institutions and $499,000 related to interest rate swaps with customers at March 31, 2017. The credit risk associated with customer transactions is partially mitigated as these transactions are generally secured by the non-cash collateral securing the underlying transaction being hedged. We had no credit exposure related to interest rate swaps with financial or customer counterparties at December 31, 2016.
[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 Instrume59

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, 2017	Dec. 31, 2016
Financial Institution Counterparties | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	[1]	$ 46,196	$ 2,182
Remaining Maturity (in years)		10 years 3 months 19 days	9 years 8 months
Weighted Average Receive Rate		0.83%	0.62%
Weighted Average Pay Rate		2.32%	1.57%
Financial Institution Counterparties | Cash Flow Hedging | Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	[1]	$ 240,000	$ 250,000
Remaining Maturity (in years)		6 years	5 years 5 months 6 days
Weighted Average Receive Rate		0.91%	0.68%
Weighted Average Pay Rate		1.43%	1.31%
Customer Counterparties | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	[1]	$ 46,196	$ 2,182
Remaining Maturity (in years)		10 years 3 months 19 days	9 years 8 months
Weighted Average Receive Rate		2.32%	1.57%
Weighted Average Pay Rate		0.83%	0.62%
[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.

Fair Value Measurement - Fair

Fair Value Measurement - Fair Value Measurements, Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		$ 65,134	$ 75,989
Total liability recurring fair value measurements		0	0
Total asset nonrecurring fair value measurements		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreclosed assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset nonrecurring fair value measurements		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset nonrecurring fair value measurements	[1]	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		0	0
Total liability recurring fair value measurements		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		59,214	70,069
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]
Total asset recurring fair value measurements		0	0
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]
Total asset recurring fair value measurements		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		5,920	5,920
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]
Total asset recurring fair value measurements	[2]	0	0
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]
Total asset recurring fair value measurements	[2]	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		1,386,903	1,410,765
Total liability recurring fair value measurements		626	85
Total asset nonrecurring fair value measurements		0	0
Significant Other Observable Inputs (Level 2) | Foreclosed assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset nonrecurring fair value measurements		0	0
Significant Other Observable Inputs (Level 2) | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset nonrecurring fair value measurements	[1]	0	0
Significant Other Observable Inputs (Level 2) | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		7,994	7,154
Total liability recurring fair value measurements		626	85
Significant Other Observable Inputs (Level 2) | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		0	0
Significant Other Observable Inputs (Level 2) | State and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		320,847	385,197
Significant Other Observable Inputs (Level 2) | Other Stocks and Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		6,658	6,651
Significant Other Observable Inputs (Level 2) | Other Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		0	0
Significant Other Observable Inputs (Level 2) | Residential MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements	[2]	684,662	627,508
Significant Other Observable Inputs (Level 2) | Commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements	[2]	366,742	384,255
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		0	0
Total liability recurring fair value measurements		0	0
Total asset nonrecurring fair value measurements		9,530	10,081
Significant Unobservable Inputs (Level 3) | Foreclosed assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset nonrecurring fair value measurements		393	388
Significant Unobservable Inputs (Level 3) | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset nonrecurring fair value measurements	[1]	9,137	9,693
Significant Unobservable Inputs (Level 3) | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		0	0
Total liability recurring fair value measurements		0	0
Significant Unobservable Inputs (Level 3) | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		0	0
Significant Unobservable Inputs (Level 3) | State and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		0	0
Significant Unobservable Inputs (Level 3) | Other Stocks and Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		0	0
Significant Unobservable Inputs (Level 3) | Other Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		0	0
Significant Unobservable Inputs (Level 3) | Residential MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements	[2]	0	0
Significant Unobservable Inputs (Level 3) | Commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements	[2]	0	0
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		1,452,037	1,486,754
Total liability recurring fair value measurements		626	85
Total asset nonrecurring fair value measurements		9,530	10,081
Carrying Amount | Foreclosed assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset nonrecurring fair value measurements		393	388
Carrying Amount | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset nonrecurring fair value measurements	[1]	9,137	9,693
Carrying Amount | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		7,994	7,154
Total liability recurring fair value measurements		626	85
Carrying Amount | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		59,214	70,069
Carrying Amount | State and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		320,847	385,197
Carrying Amount | Other Stocks and Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		6,658	6,651
Carrying Amount | Other Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements		5,920	5,920
Carrying Amount | Residential MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements	[2]	684,662	627,508
Carrying Amount | Commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total asset recurring fair value measurements	[2]	$ 366,742	$ 384,255
[1]	Impaired loans represent collateral-dependent loans with a specific valuation allowance. Losses on these loans represent charge-offs which are netted against the allowance for loan losses.
[2]	All mortgage-backed securities are issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Fair Value Measurement - Fai61

Fair Value Measurement - Fair Value, Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Level 1
Financial Assets:
Cash and cash equivalents	$ 246,994	$ 169,654
Investment Securities:
Held to maturity, at carrying value	0	0
Mortgage-backed Securities:
Held to maturity, at carrying value	0	0
FHLB stock, at cost, and other investments	0	0
Loans, net of allowance for loan losses	0	0
Loans held for sale	0	0
Financial Liabilities:
Deposits	0	0
Federal funds purchased and repurchase agreements	0	0
FHLB advances	0	0
Subordinated notes	0	0
Long-term debt, net of unamortized debt issuance costs	0	0
Level 2
Financial Assets:
Cash and cash equivalents	0	0
Investment Securities:
Held to maturity, at carrying value	427,288	429,912
Mortgage-backed Securities:
Held to maturity, at carrying value	513,121	514,370
FHLB stock, at cost, and other investments	66,747	66,592
Loans, net of allowance for loan losses	0	0
Loans held for sale	5,303	7,641
Financial Liabilities:
Deposits	3,701,697	3,293,352
Federal funds purchased and repurchase agreements	7,814	7,097
FHLB advances	1,206,415	1,331,517
Subordinated notes	100,561	101,627
Long-term debt, net of unamortized debt issuance costs	45,572	45,147
Level 3
Financial Assets:
Cash and cash equivalents	0	0
Investment Securities:
Held to maturity, at carrying value	0	0
Mortgage-backed Securities:
Held to maturity, at carrying value	0	0
FHLB stock, at cost, and other investments	0	0
Loans, net of allowance for loan losses	2,601,382	2,630,009
Loans held for sale	0	0
Financial Liabilities:
Deposits	0	0
Federal funds purchased and repurchase agreements	0	0
FHLB advances	0	0
Subordinated notes	0	0
Long-term debt, net of unamortized debt issuance costs	0	0
Carrying Amount
Financial Assets:
Cash and cash equivalents	246,994	169,654
Investment Securities:
Held to maturity, at carrying value	421,133	425,810
Mortgage-backed Securities:
Held to maturity, at carrying value	508,660	511,677
FHLB stock, at cost, and other investments	66,747	66,592
Loans, net of allowance for loan losses	2,520,433	2,538,626
Loans held for sale	5,303	7,641
Financial Liabilities:
Deposits	3,705,296	3,533,076
Federal funds purchased and repurchase agreements	7,814	7,097
FHLB advances	1,205,856	1,309,646
Subordinated notes	98,133	98,100
Long-term debt, net of unamortized debt issuance costs	60,237	60,236
Estimated Fair Value
Financial Assets:
Cash and cash equivalents	246,994	169,654
Investment Securities:
Held to maturity, at carrying value	427,288	429,912
Mortgage-backed Securities:
Held to maturity, at carrying value	513,121	514,370
FHLB stock, at cost, and other investments	66,747	66,592
Loans, net of allowance for loan losses	2,601,382	2,630,009
Loans held for sale	5,303	7,641
Financial Liabilities:
Deposits	3,701,697	3,293,352
Federal funds purchased and repurchase agreements	7,814	7,097
FHLB advances	1,206,415	1,331,517
Subordinated notes	100,561	101,627
Long-term debt, net of unamortized debt issuance costs	$ 45,572	$ 45,147

Income Taxes - Provision for I

Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Current income tax expense	$ 3,027	$ 3,785
Deferred income tax (benefit) expense	(19)	(812)
Income tax expense	$ 3,008	$ 2,973

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net deferred tax assets	$ 26,800,000		$ 28,900,000
Deferred tax assets, valuation allowance	0		$ 0
Income tax expense	$ 3,008,000	$ 2,973,000
Effective income tax rate, percent	16.70%	18.00%
Income tax expense (benefit) related to excess tax benefit on share-based compensation	$ 126,000
ETR, discrete tax increase (decrease), percent	0.70%

Off-Balance-Sheet Arrangement64

Off-Balance-Sheet Arrangements, Commitments and Contingencies (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	$ 674,819	$ 674,738
Commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	666,207	665,663
Standby letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	$ 8,612	$ 9,075

Off-Balance-Sheet Arrangement65

Off-Balance-Sheet Arrangements, Commitments and Contingencies Narrative (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Securities:
Unsettled trades to purchase securities	$ 10,465,000	$ 160,000	$ 23,920,000
Unsettled trades to sell securities	57,385,000	0	15,039,000
Deposits:
Unsettled issuances of brokered certificates of deposit	$ 31,232,000	$ 0	$ 0