Simmons First National (SFNC) 10-K 27 Feb 19 2018 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 13, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	SIMMONS FIRST NATIONAL CORP
Entity Central Index Key	90,498
Trading Symbol	sfnc
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		92,523,606
Entity Public Float			$ 2,680,880,943
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
ASSETS
Cash and non-interest bearing balances due from banks		$ 171,792	$ 205,025
Interest bearing balances due from banks and federal funds sold		661,666	393,017
Cash and cash equivalents		833,458	598,042
Interest bearing balances due from banks – time		4,934	3,314
Investment securities:
Held-to-maturity		289,194	368,058
Available-for-sale		2,151,752	1,589,517
Total investments		2,440,946	1,957,575
Mortgage loans held for sale		26,799	24,038
Other assets held for sale		1,790	165,780
Loans:
Legacy loans		8,430,388	5,705,609
Allowance for loan losses		(56,599)	(41,668)
Loans acquired, net of discount and allowance		3,292,783	5,074,076
Net loans		11,666,572	10,738,017
Premises and equipment		295,060	287,249
Foreclosed assets and other real estate owned		25,565	32,118
Interest receivable		49,938	43,528
Bank owned life insurance		193,170	185,984
Goodwill		845,687	842,651
Other intangible assets		91,334	106,071
Other assets		68,084	71,439
Total assets		16,543,337	15,055,806
Deposits:
Non-interest bearing transaction accounts		2,672,405	2,665,249
Interest bearing transaction accounts and savings deposits		6,830,191	6,494,896
Time deposits		2,896,156	1,932,730
Total deposits		12,398,752	11,092,875
Federal funds purchased and securities sold under agreements to repurchase		95,792	122,444
Other borrowings		1,345,450	1,380,024
Subordinated debentures		353,950	140,565
Other liabilities held for sale		162	157,366
Accrued interest and other liabilities		102,797	77,968
Total liabilities		14,296,903	12,971,242
Stockholders’ equity:
Common stock, Class A, $0.01 par value; 175,000,000 and 120,000,000 shares authorized at December 31, 2018 and 2017, respectively (1); 92,347,643 and 92,029,118 shares issued and outstanding at December 31, 2018 and 2017, respectively	[1]	923	920
Surplus		1,597,944	1,586,034
Undivided profits		674,941	514,874
Accumulated other comprehensive loss		(27,374)	(17,264)
Total stockholders’ equity		2,246,434	2,084,564
Total liabilities and stockholders’ equity		$ 16,543,337	$ 15,055,806
[1]	On April 19, 2018, shareholders of the Company approved an increase in the number of authorized shares from 120,000,000 to 175,000,000.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common stock, Class A, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, Class A, shares authorized (in shares)	175,000,000	120,000,000
Common stock, Class A, shares issued (in shares)	92,347,643	92,029,118
Common stock, Class A, shares outstanding (in shares)	92,347,643	92,029,118

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
INTEREST INCOME
Loans		$ 616,037	$ 352,351	$ 265,652
Interest bearing balances due from banks and federal funds sold		5,996	1,933	756
Investment securities		57,318	40,115	33,479
Mortgage loans held for sale		1,336	605	1,102
Assets held in trading accounts		0	0	16
TOTAL INTEREST INCOME		680,687	395,004	301,005
INTEREST EXPENSE
Deposits		87,210	27,756	15,217
Federal funds purchased and securities sold under agreements to repurchase		423	347	273
Other borrowings		23,654	8,621	4,148
Subordinated notes and debentures		16,848	3,350	2,161
TOTAL INTEREST EXPENSE		128,135	40,074	21,799
NET INTEREST INCOME		552,552	354,930	279,206
Provision for loan losses		38,148	26,393	20,065
NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES		514,404	328,537	259,141
NON-INTEREST INCOME
Investment banking income		3,141	2,793	3,471
Bank owned life insurance income		4,415	3,503	3,324
Gain on sale of securities, net		61	1,059	5,848
Other income		19,863	19,268	18,788
TOTAL NON-INTEREST INCOME		143,896	138,765	139,382
NON-INTEREST EXPENSE
Salaries and employee benefits		216,743	154,314	133,457
Occupancy expense, net		29,610	21,159	18,667
Furniture and equipment expense		16,323	19,366	16,683
Other real estate and foreclosure expense		4,480	3,042	4,461
Deposit insurance		8,721	3,696	3,469
Merger related costs		4,777	21,923	4,835
Other operating expenses		111,575	88,879	73,513
TOTAL NON-INTEREST EXPENSE		392,229	312,379	255,085
INCOME BEFORE INCOME TAXES		266,071	154,923	143,438
Provision for income taxes		50,358	61,983	46,624
NET INCOME		215,713	92,940	96,814
Preferred stock dividends		0	0	24
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS		$ 215,713	$ 92,940	$ 96,790
Basic earnings per share (in dollars per share)	[1]	$ 2.34	$ 1.34	$ 1.58
Diluted earnings per share (in dollars per share)	[1]	$ 2.32	$ 1.33	$ 1.56
Trust income
NON-INTEREST INCOME
NON-INTEREST INCOME		$ 23,128	$ 18,570	$ 15,442
Service charges on deposit accounts
NON-INTEREST INCOME
NON-INTEREST INCOME		42,508	36,079	32,414
Other service charges and fees
NON-INTEREST INCOME
NON-INTEREST INCOME		7,469	9,919	12,872
Mortgage and SBA lending income
NON-INTEREST INCOME
NON-INTEREST INCOME		11,043	13,316	16,483
Debit and credit card fees
NON-INTEREST INCOME
NON-INTEREST INCOME		$ 32,268	$ 34,258	$ 30,740
[1]	Per share amounts for the years ended 2017 and 2016 have been restated to reflect the effect of the two-for-one stock split on February 8, 2018.

Consolidated Statements of In_2

Consolidated Statements of Income (Parentheticals)	Feb. 08, 2018	Feb. 28, 2018
Income Statement [Abstract]
Stock split, conversion ratio	2	2

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 215,713	$ 92,940	$ 96,814
OTHER COMPREHENSIVE (LOSS) INCOME
Unrealized holding (losses) gains arising during the period on available-for-sale securities	(13,626)	2,645	(14,797)
Less: Reclassification adjustment for realized gains included in net income	61	1,059	5,848
Other comprehensive (loss) income, before tax effect	(13,687)	1,586	(20,645)
Less: Tax effect of other comprehensive (loss) income	(3,577)	622	(8,098)
TOTAL OTHER COMPREHENSIVE (LOSS) INCOME	(10,110)	964	(12,547)
COMPREHENSIVE INCOME	$ 205,603	$ 93,904	$ 84,267

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES
Net income	$ 215,713	$ 92,940	$ 96,814
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	28,412	21,062	16,978
Provision for loan losses	38,148	26,393	20,065
Gain on sale of investments	(61)	(1,059)	(5,848)
Net accretion of investment securities and assets	(48,684)	(38,090)	(31,928)
Net (accretion) amortization on borrowings	(380)	561	421
Stock-based compensation expense	9,725	10,681	3,418
Gain on sale of premises and equipment held for sale, net of impairment	0	(615)	(225)
Gain on sale of foreclosed assets and other real estate owned	(650)	(1,076)	(2,432)
Gain on sale of mortgage loans held for sale	(12,844)	(12,186)	(14,683)
Gain on sale of loans	(10)	(18)	0
Fair value write-down of closed branches	836	325	3,000
Deferred income taxes	8,412	23,251	9,832
Gain on sale of insurance lines of business	0	(3,708)	0
Income from bank owned life insurance	(5,003)	(3,503)	(3,372)
Originations of mortgage loans held for sale	(546,676)	(507,907)	(618,453)
Proceeds from sale of mortgage loans held for sale	556,759	526,245	635,613
Changes in assets and liabilities:
Interest receivable	(6,227)	(2,432)	(1,197)
Assets held in trading accounts	0	41	4,381
Other assets	(1,414)	12,456	(8,206)
Accrued interest and other liabilities	33,978	(14,194)	(14,959)
Income taxes payable	(9,355)	(14,604)	1,915
Net cash provided by operating activities	260,679	114,563	91,134
INVESTING ACTIVITIES
Net originations of loans	(912,793)	(719,219)	(368,162)
Proceeds from sale of loans	24,977	20,705	0
(Increase) decrease in due from banks - time	(1,620)	3,233	9,544
Purchases of premises and equipment, net	(29,740)	(34,216)	(18,892)
Proceeds from sale of premises and equipment	0	3,475	1,628
Purchases of other real estate owned	0	(1,021)	0
Proceeds from sale of foreclosed assets and other real estate owned	27,751	18,255	29,055
Proceeds from sale of available-for-sale securities	7,959	679,613	346,273
Proceeds from maturities of available-for-sale securities	258,325	487,717	257,388
Purchases of available-for-sale securities	(825,914)	(854,708)	(861,572)
Proceeds from maturities of held-to-maturity securities	80,803	97,494	250,636
Purchases of held-to-maturity securities	(1,172)	(860)	(6,162)
Proceeds from bank owned life insurance death benefits	1,814	0	3,039
Purchases of bank owned life insurance	(4,000)	(143)	(143)
Proceeds from the sale of insurance lines of business	0	9,296	0
Cash paid in business combinations, net of cash received	0	(48,092)	0
Cash received in business combinations, net of cash paid	0	0	106,419
Disposition of assets and liabilities held for sale	(55,211)	0	0
Net cash used in investing activities	(1,428,821)	(338,471)	(250,949)
FINANCING ACTIVITIES
Net change in deposits	1,305,877	120,667	139,266
Proceeds from issuance of subordinated notes	326,355	0	0
Repayments of subordinated debentures and subordinated debt	(113,990)	(3,000)	(594)
Dividends paid on preferred stock	0	0	(24)
Dividends paid on common stock	(55,646)	(35,116)	(28,743)
Net change in other borrowed funds	(34,574)	521,865	106,823
Net change in federal funds purchased and securities sold under agreements to repurchase	(26,652)	(71,003)	2,398
Net shares issued under stock compensation plans	1,162	2,260	4,352
Shares issued under employee stock purchase plan	1,026	618	586
Redemption of preferred stock	0	0	(30,852)
Net cash provided by financing activities	1,403,558	536,291	193,212
INCREASE IN CASH EQUIVALENTS	235,416	312,383	33,397
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	598,042	285,659	252,262
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 833,458	$ 598,042	$ 285,659

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total	Preferred Stock	Common Stock	Surplus	Accumulated Other Comprehensive Income (Loss)	Undivided Profits	Hardeman County Investment Company, Inc.	Hardeman County Investment Company, Inc.Common Stock	Hardeman County Investment Company, Inc.Surplus	OKSB Merger	OKSB MergerCommon Stock	OKSB MergerSurplus	First Texas Merger	First Texas MergerCommon Stock	First Texas MergerSurplus
Balance at Dec. 31, 2015		$ 1,076,855	$ 30,852	$ 606	$ 662,075	$ (2,665)	$ 385,987
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income		84,267				(12,547)	96,814
Stock issued for employee stock purchase plan		586			586
Stock-based compensation plans, net		7,770		3	7,767
Stock issued for acquisition		41,252		17	41,235
Preferred stock redeemed		(30,852)	(30,852)
Dividends on preferred stock		(24)					(24)
Dividends on common stock	[1]	(28,743)					(28,743)
Balance at Dec. 31, 2016		1,151,111	0	626	711,663	(15,212)	454,034
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income		93,904				964	92,940
Reclassify stranded tax effects due to 2017 tax law changes		0				(3,016)	3,016
Stock issued for employee stock purchase plan		618			618
Stock-based compensation plans, net		12,941		3	12,938
Stock issued for acquisition								$ 42,638	$ 16	$ 42,622	$ 431,398	$ 145	$ 431,253	$ 387,070	$ 130	$ 386,940
Dividends on common stock	[1]	(35,116)					(35,116)
Balance at Dec. 31, 2017		2,084,564	0	920	1,586,034	(17,264)	514,874
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income		205,603				(10,110)	215,713
Stock issued for employee stock purchase plan		1,026			1,026
Stock-based compensation plans, net		10,887		3	10,884
Dividends on common stock		(55,646)					(55,646)
Balance at Dec. 31, 2018		$ 2,246,434	$ 0	$ 923	$ 1,597,944	$ (27,374)	$ 674,941
[1]	All share and per share amounts for the years ended 2017 and 2016 have been restated to reflect the effect of the two-for-one stock split on February 8, 2018.

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parentheticals)		12 Months Ended
		Dec. 31, 2018$ / sharesshares	Dec. 31, 2017$ / sharesshares		Dec. 31, 2016$ / sharesshares
Stock issued for employee stock purchase plan, shares (in shares)		39,782	26,002	[1]	31,470	[1]
Stock issued for compensation plans, shares (in shares)		278,743	359,286	[1]	295,630	[1]
Cash dividends, per share (in dollars per share) | $ / shares		$ 0.60	$ 0.50	[1]	$ 0.48	[1]
Citizens National Bank
Stock issued for acquisition, shares (in shares)	[1]				1,671,482
Hardeman County Investment Company, Inc.
Stock issued for acquisition, shares (in shares)	[1]		1,599,940
OKSB Merger
Stock issued for acquisition, shares (in shares)	[1]		14,488,604
First Texas Merger
Stock issued for acquisition, shares (in shares)	[1]		12,999,840
[1]	All share and per share amounts for the years ended 2017 and 2016 have been restated to reflect the effect of the two-for-one stock split on February 8, 2018.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of Operations and Principles of Consolidation Simmons First National Corporation (the “Company”) is primarily engaged in providing a full range of banking services to individual and corporate customers through its subsidiaries and their branch banks with offices. We are headquartered in Pine Bluff, Arkansas and conduct banking operations in communities throughout Arkansas, Colorado, Kansas, Missouri, Oklahoma, Tennessee and Texas. We offer consumer, real estate and commercial loans, checking, savings and time deposits from our 191 financial centers conveniently located throughout our market areas. Additionally, we offer specialized products and services such as credit cards, trust and fiduciary services, investments, agricultural finance lending, equipment lending, insurance and small business administration (“SBA”) lending. The Company is subject to regulation of certain federal and state agencies and undergoes periodic examinations by those regulatory authorities. The consolidated financial statements include the accounts of the Company and its subsidiaries. Significant intercompany accounts and transactions have been eliminated in consolidation. Operating Segments Operating segments are components of an enterprise about which separate financial information is available that is regularly evaluated by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company is organized on a divisional basis. Each of the divisions provide a group of similar community banking services, including such products and services as loans; time deposits, checking and savings accounts; personal and corporate trust services; credit cards; investment management; insurance; and securities and investment services. Loan products include consumer, real estate, commercial, agricultural, equipment and SBA lending. The individual bank divisions have similar operating and economic characteristics. While the chief operating decision maker monitors the revenue streams of the various products, services, branch locations and divisions, operations are managed, financial performance is evaluated, and management makes decisions on how to allocate resources on a Company-wide basis. Accordingly, the divisions are considered by management to be aggregated into one reportable operating segment, community banking. The Company also considers its trust, investment and insurance services to be operating segments. Information on these segments is not reported separately since they do not meet the quantitative thresholds under Accounting Standards Codification (“ASC”) Topic 280-10-50-12. Use of Estimates The preparation of financial statements, in accordance with accounting principles generally accepted in the United States (“US GAAP”), requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, income and expenses and disclosure of contingent assets and liabilities. The estimates and assumptions used in the accompanying consolidated financial statements are based upon management’s evaluation of the relevant facts and circumstances as of the date of the consolidated financial statements and actual results may differ from these estimates. Material estimates that are particularly susceptible to significant change relate to the determination of the allowance for loan losses, the valuation of real estate acquired in connection with foreclosures or in satisfaction of loans and the valuation of acquired loans. Management obtains independent appraisals for significant properties in connection with the determination of the allowance for loan losses and the valuation of foreclosed assets. Reclassifications Various items within the accompanying consolidated financial statements for previous years have been reclassified to provide more comparative information. These reclassifications were not material to the consolidated financial statements. Cash Equivalents The Company considers all liquid investments with original maturities of three months or less to be cash equivalents. For purposes of the consolidated statements of cash flows, cash and cash equivalents are considered to include cash and non-interest bearing balances due from banks, interest bearing balances due from banks and federal funds sold and securities purchased under agreements to resell. Investment Securities Held-to-maturity securities, which include any security for which the Company has the positive intent and ability to hold until maturity, are carried at historical cost adjusted for amortization of premiums and accretion of discounts. Premiums and discounts are amortized and accreted, respectively, to interest income using the constant yield method over the period to maturity. Available-for-sale securities, which include any security for which the Company has no immediate plan to sell but which may be sold in the future, are carried at fair value. Realized gains and losses, based on specifically identified amortized cost of the individual security, are included in other income. Unrealized gains and losses are recorded, net of related income tax effects, in stockholders’ equity. Premiums and discounts are amortized and accreted, respectively, to interest income using the constant yield method over the period to maturity. Trading securities, which include any security held primarily for near-term sale, are carried at fair value. Gains and losses on trading securities are included in other income. The Company applies accounting guidance related to recognition and presentation of other-than-temporary impairment under ASC Topic 320-10. When the Company does not intend to sell a debt security, and it is more likely than not, the Company will not have to sell the security before recovery of its cost basis, it recognizes the credit component of an other-than-temporary impairment of a debt security in earnings and the remaining portion in other comprehensive income. For held-to-maturity debt securities, the amount of an other-than-temporary impairment recorded in other comprehensive income for the noncredit portion of a previous other-than-temporary impairment is amortized prospectively over the remaining life of the security on the basis of the timing of future estimated cash flows of the security. As a result of this guidance, the Company’s consolidated statements of income reflect the full impairment (that is, the difference between the security’s amortized cost basis and fair value) on debt securities that the Company intends to sell or would more likely than not be required to sell before the expected recovery of the amortized cost basis. For available-for-sale and held-to-maturity debt securities that management has no intent to sell and believes that it more likely than not will not be required to sell prior to recovery, only the credit loss component of the impairment is recognized in earnings, while the noncredit loss is recognized in accumulated other comprehensive income. The credit loss component recognized in earnings is identified as the amount of principal cash flows not expected to be received over the remaining term of the security as projected based on cash flow projections. Mortgage Loans Held For Sale Mortgage Loans Held for Sale are carried at fair value which is determined on an aggregate basis. Adjustments to fair value are recognized monthly and reflected in earnings. The Company regularly sells mortgages into the capital markets to mitigate the effects of interest rate volatility during the period from the time an interest rate lock commitment (IRLC) is issued until the IRLC funds creating a mortgage loan held for sale and its subsequent sale into the secondary/capital markets. Loan sales are typically executed on a mandatory basis. Under a mandatory commitment, the Company agrees to deliver a specified dollar amount with predetermined terms by a certain date. Generally, the commitment is not loan specific, and any combination of loans can be delivered into the outstanding commitment provided the terms fall within the parameters of the commitment. Upon failure to deliver, the Company is subject to fees based on market movement. The IRLCs are derivative instruments; their fair values at December 31, 2018 and 2017 were not material. Gains and losses resulting from sales of mortgage loans are recognized when the respective loans are sold to correspondent lenders, investors or aggregators. Gains and losses are determined by the difference between the sale price and the carrying amount in the loans sold, net of discounts collected, or premiums paid. Hedge instruments are, likewise, carried at fair value and associated gains/losses are realized at time of settlement. Loans Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-offs are reported at their outstanding principal adjusted for any loans charged off, the allowance for loan losses and any unamortized deferred fees or costs on originated loans and unamortized premiums or discounts on purchased loans. For loans amortized at cost, interest income is accrued based on the unpaid principal balance. Loan origination fees, net of certain direct origination costs, as well as premiums and discounts, are deferred and amortized as a level yield adjustment over the respective term of the loan. The accrual of interest on loans, except on certain government guaranteed loans, is discontinued at the time the loan is 90 days past due unless the credit is well-secured and in process of collection. Past due status is based on contractual terms of the loan. In all cases, loans are placed on nonaccrual or charged off at an earlier date if collection of principal or interest is considered doubtful. Discounts and premiums on purchased residential real estate loans are amortized to income using the interest method over the remaining period to contractual maturity, adjusted for anticipated prepayments. Discounts and premiums on purchased consumer loans are recognized over the expected lives of the loans using methods that approximate the interest method. For discussion of the Company’s accounting for acquired loans, see Acquisition Accounting, Acquired Loans later in this section. Allowance for Loan Losses The allowance for loan losses is management’s estimate of probable losses in the loan portfolio. Loan losses are charged against the allowance when management believes the uncollectability of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. Allocations to the allowance for loan losses are categorized as either general reserves or specific reserves. The allowance for loan losses is calculated monthly based on management’s assessment of several factors such as (1) historical loss experience based on volumes and types, (2) volume and trends in delinquencies and nonaccruals, (3) lending policies and procedures including those for loan losses, collections and recoveries, (4) national, state and local economic trends and conditions, (5) external factors and pressure from competition, (6)the experience, ability and depth of lending management and staff, (7) seasoning of new products obtained and new markets entered through acquisition and (8) other factors and trends that will affect specific loans and categories of loans. The Company establishes general allocations for each major loan category. This category also includes allocations to loans which are collectively evaluated for loss such as credit cards, one-to-four family owner occupied residential real estate loans and other consumer loans. General reserves have been established, based upon the aforementioned factors and allocated to the individual loan categories. Specific reserves are provided on loans that are considered impaired when it is probable that we will not receive all amounts due according to the contractual terms of the loan, including scheduled principal and interest payments. This includes loans that are delinquent 90 days or more, nonaccrual loans and certain other loans identified by management. Certain other loans identified by management consist of performing loans where management expects that the Company will not receive all amounts due according to the contractual terms of the loan, including scheduled principal and interest payments. Specific reserves are accrued for probable losses on specific loans evaluated for impairment for which the basis of each loan, including accrued interest, exceeds the discounted amount of expected future collections of interest and principal or, alternatively, the fair value of loan collateral. Accrual of interest is discontinued and interest accrued and unpaid is removed at the time such amounts are delinquent 90 days unless management is aware of circumstances which warrant continuing the interest accrual. Interest is recognized for nonaccrual loans only upon receipt and only after all principal amounts are current according to the terms of the contract. Management’s evaluation of the allowance for loan losses is inherently subjective as it requires material estimates. The actual amounts of loan losses realized in the near term could differ from the amounts estimated in arriving at the allowance for loan losses reported in the financial statements. Reserve for Unfunded Commitments In addition to the allowance for loan losses, the Company has established a reserve for unfunded commitments, classified in other liabilities. This reserve is maintained at a level sufficient to absorb losses arising from unfunded loan commitments. The adequacy of the reserve for unfunded commitments is determined monthly based on methodology similar to the Company’s methodology for determining the allowance for loan losses. Net adjustments to the reserve for unfunded commitments are included in other non-interest expense. Acquisition Accounting, Acquired Loans The Company accounts for its acquisitions under ASC Topic 805, Business Combinations , which requires the use of the acquisition method of accounting. All identifiable assets acquired, including loans, are recorded at fair value. No allowance for loan losses related to the acquired loans is recorded on the acquisition date as the fair value of the loans acquired incorporates assumptions regarding credit risk. Loans acquired are recorded at fair value in accordance with the fair value methodology prescribed in ASC Topic 820. The fair value estimates associated with the loans include estimates related to expected prepayments and the amount and timing of undiscounted expected principal, interest and other cash flows. The Company evaluates non-impaired loans acquired in accordance with the provisions of ASC Topic 310-20, Nonrefundable Fees and Other Costs . The fair value discount on these loans is accreted into interest income over the weighted average life of the loans using a constant yield method. The Company evaluates purchased impaired loans in accordance with the provisions of ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality . Purchased loans are considered impaired if there is evidence of credit deterioration since origination and if it is probable that not all contractually required payments will be collected. For impaired loans accounted for under ASC Topic 310-30, the Company continues to estimate cash flows expected to be collected on purchased credit impaired loans. The Company evaluates at each balance sheet date whether the present value of the purchased credit impaired loans determined using the effective interest rates has decreased significantly and if so, recognize a provision for loan loss in our consolidated statement of income. For any significant increases in cash flows expected to be collected, the Company adjusts the amount of accretable yield recognized on a prospective basis over the remaining life of the purchased credit impaired loan. For further discussion of our acquisition and loan accounting, see Note 2, Acquisitions, and Note 6, Loans Acquired. Trust Assets Trust assets (other than cash deposits) held by the Company in fiduciary or agency capacities for its customers are not included in the accompanying consolidated balance sheets since such items are not assets of the Company. Premises and Equipment Depreciable assets are stated at cost less accumulated depreciation. Depreciation is charged to expense using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are capitalized and amortized by the straight-line method over the terms of the respective leases or the estimated useful lives of the improvements, whichever is shorter. Foreclosed Assets Held For Sale Assets acquired by foreclosure or in settlement of debt and held for sale are valued at estimated fair value as of the date of foreclosure, and a related valuation allowance is provided for estimated costs to sell the assets. Management evaluates the value of foreclosed assets held for sale periodically and increases the valuation allowance for any subsequent declines in fair value. Changes in the valuation allowance are charged or credited to other expense. Bank Owned Life Insurance The Company maintains bank-owned life insurance policies on certain current and former employees and directors, which are recorded at their cash surrender values as determined by the insurance carriers. The appreciation in the cash surrender value of the policies is recognized as a component of non-interest income in the Company’s consolidated statements of income. Goodwill and Intangible Assets Goodwill represents the excess of the cost of an acquisition over the fair value of the net assets acquired. Other intangible assets represent purchased assets that also lack physical substance but can be separately distinguished from goodwill because of contractual or other legal rights or because the asset is capable of being sold or exchanged either on its own or in combination with a related contract, asset or liability. The Company performs an annual goodwill impairment test, and more frequently if circumstances warrant, in accordance with ASC Topic 350, Intangibles – Goodwill and Other . ASC Topic 350 requires that goodwill and intangible assets that have indefinite lives be reviewed for impairment annually, or more frequently if certain conditions occur. Intangible assets with finite lives are amortized over the estimated life of the asset, and are reviewed for impairment whenever events or changes in circumstances indicated that the carrying value may not be recoverable. Impairment losses, if any, will be recorded as operating expenses. Derivative Financial Instruments The Company may enter into derivative contracts for the purposes of managing exposure to interest rate risk to meet the financing needs of its customers. The Company records all derivatives on the balance sheet at fair value. In an effort to meet the financing needs of its customers, the Company has entered into limited fair value hedges. Fair value hedges include interest rate swap agreements on fixed rate loans. To qualify for hedge accounting, derivatives must be highly effective at reducing the risk associated with the exposure being hedged and must be designated as a hedge at the point of inception of the derivative contract. For derivatives designated as hedging the exposure to changes in the fair value of the hedged item, the gain or loss is recognized in earnings in the period of change together with the offsetting loss or gain of the hedging instrument. The fair value hedges are considered to be highly effective and any hedge ineffectiveness was deemed not material. Fair value adjustments related to cash flow hedges are recorded in other comprehensive income and are reclassified to earnings when the hedged transaction is reflected in earnings. The notional amount of the swaps was $561.3 million at December 31, 2018 and $303.5 million at December 31, 2017 . Securities Sold Under Agreements to Repurchase The Company sells securities under agreements to repurchase to meet customer needs for sweep accounts. At the point funds deposited by customers become investable, those funds are used to purchase securities owned by the Company and held in its general account with the designation of Customers’ Securities. A third party maintains control over the securities underlying overnight repurchase agreements. The securities involved in these transactions are generally U.S. Treasury or Federal Agency issues. Securities sold under agreements to repurchase generally mature on the banking day following that on which the investment was initially purchased and are treated as collateralized financing transactions which are recorded at the amounts at which the securities were sold plus accrued interest. Interest rates and maturity dates of the securities involved vary and are not intended to be matched with funds from customers. Revenue from Contracts with Customers ASC Topic 606, Revenue from Contracts with Customers , applies to all contracts with customers to provide goods or services in the ordinary course of business. However, Topic 606 specifically does not apply to revenue related to financial instruments, guarantees, insurance contracts, leases, or nonmonetary exchanges. Given these scope exceptions, interest income recognition and measurement related to loans and investments securities, the Company’s two largest sources of revenue, are not accounted for under Topic 606. Also, the Company does not use Topic 606 to account for gains or losses on its investments in securities, loans, and derivatives due to the scope exceptions. Certain revenue streams, such as service charges on deposit accounts, gains or losses on the sale of OREO, and trust income, fall under the scope of Topic 606 and the Company must recognize revenue at an amount that reflects the consideration to which the Company expects to be entitled in exchange for transferring goods or services to a customer. Topic 606 is applied using five steps: 1) identify the contract with the customer, 2) identify the performance obligations in the contract, 3) determine the transaction price, 4) allocate the transaction price to the performance obligations in the contract, and 5) recognize revenue when (or as) the entity satisfies a performance obligation. The Company has evaluated the nature of all contracts with customers that fall under the scope of Topic 606 and determined that further disaggregation of revenue from contracts with customers into categories was not necessary. There has not been significant revenue recognized in the current reporting periods resulting from performance obligations satisfied in previous periods. In addition, there has not been a significant change in timing of revenues received from customers. A description of performance obligations for each type of contract with customers is as follows: Service charges on deposit accounts – The Company’s primary source of funding comes from deposit accounts with its customers. Customers pay certain fees to access their cash on deposit including, but not limited to, non-transactional fees such as account maintenance, dormancy or statement rendering fees, and certain transaction-based fees such as ATM, wire transfer, overdraft or returned check fees. The Company generally satisfies its performance obligations as services are rendered. The transaction prices are fixed, and are charged either on a periodic basis or based on activity. Sale of OREO – In the normal course of business, the Company will enter into contracts with customers to sell OREO, which has generally been foreclosed upon by the Company. The Company generally satisfies its performance obligation upon conveyance of property from the Company to the customer, generally by way of an executed agreement. The transaction price is fixed, and on occasion the Company will finance a portion of the proceeds the customers uses to purchase the property. These properties are generally sold without recourse or warranty. Trust Income – The Company enters into contracts with its customers to manage assets for investment, and/or transact on their accounts. The Company generally satisfies its performance obligations as services are rendered. The management fee is a fixed percentage-based fee calculated upon the average balance of assets under management and is charged to customers on a monthly basis. Bankcard Fee Income – Periodic bankcard fees, net of direct origination costs, are recognized as revenue on a straight-line basis over the period the fee entitles the cardholder to use the card. Income Taxes The Company accounts for income taxes in accordance with income tax accounting guidance in ASC Topic 740, Income Taxes . The income tax accounting guidance results in two components of income tax expense: current and deferred. Current income tax expense reflects taxes to be paid or refunded for the current period by applying the provisions of the enacted tax law to the taxable income or excess of deductions over revenues. The Company determines deferred income taxes using the liability (or balance sheet) method. Under this method, the net deferred tax asset or liability is based on the tax effects of the differences between the book and tax bases of assets and liabilities, and enacted changes in tax rates and laws are recognized in the period in which they occur. Deferred income tax expense results from changes in deferred tax assets and liabilities between periods. Deferred tax assets are recognized if it is more likely than not, based on the technical merits, that the tax position will be realized or sustained upon examination. The term more likely than not means a likelihood of more than 50 percent; the terms examined and upon examination also include resolution of the related appeals or litigation processes, if any. A tax position that meets the more-likely-than-not recognition threshold is initially and subsequently measured as the largest amount of tax benefit that has a greater than 50 percent likelihood of being realized upon settlement with a taxing authority that has full knowledge of all relevant information. The determination of whether or not a tax position has met the more-likely-than-not recognition threshold considers the facts, circumstances and information available at the reporting date and is subject to management’s judgment. Deferred tax assets are reduced by a valuation allowance if, based on the weight of evidence available, it is more likely than not that some portion or all of a deferred tax asset will not be realized. The Company files consolidated income tax returns with its subsidiaries. Earnings Per Share Basic earnings per share are computed based on the weighted average number of shares outstanding during each year. Diluted earnings per share are computed using the weighted average common shares and all potential dilutive common shares outstanding during the period. All share and per share amounts have been restated to reflect the effect of the two -for-one stock split during February 2018. The computation of per share earnings is as follows: (In thousands, except per share data) 2018 2017 2016 Net income available to common shareholders $ 215,713 $ 92,940 $ 96,790 Average common shares outstanding 92,268 69,385 61,291 Average potential dilutive common shares 562 468 636 Average diluted common shares 92,830 69,853 61,927 Basic earnings per share $ 2.34 $ 1.34 $ 1.58 Diluted earnings per share $ 2.32 $ 1.33 $ 1.56 There were no stock options excluded from the earnings per share calculation due to the related exercise price exceeding the average market price for the years ended December 31, 2018 , 2017 and 2016 . Stock-Based Compensation The Company has adopted various stock-based compensation plans. The plans provide for the grant of incentive stock options, nonqualified stock options, stock appreciation rights and bonus stock awards. Pursuant to the plans, shares are reserved for future issuance by the Company, upon exercise of stock options or awarding of bonus shares granted to directors, officers and other key employees. In accordance with ASC Topic 718, Compensation – Stock Compensation , the fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model that uses various assumptions. This model requires the input of highly subjective assumptions, changes to which can materially affect the fair value estimate. For additional information, see Note 14, Employee Benefit Plans. Reliance Bancshares, Inc. (Pending Acquisition) On November 13, 2018, the Company announced that it has entered into an Agreement and Plan of Merger (“Reliance Agreement”) with Reliance Bancshares, Inc. (“Reliance”), headquartered in Des Peres, Missouri, including its wholly-owned bank subsidiary, Reliance Bank. According to the terms and subject to the conditions of the Reliance Agreement, upon consummation of the transaction, holders of Reliance’s commons stock and common stock equivalents will receive, in the aggregate, 4,000,000 shares of the Company’s common stock and $62.7 million in cash. In addition, each share of Reliance’s Series A Preferred Stock and Series B Preferred Stock will be converted into the right to receive one share of Simmons’ comparable Series A Preferred Stock or Series B Preferred Stock, respectively, and each share of Reliance’s Series C Preferred Stock will be converted into the right to receive one share of Simmons’ comparable Series C Preferred Stock (unless the holder of such Series C Preferred Stock elects to receive alternative consideration in accordance with the Reliance Agreement). Reliance conducts banking business from 20 -plus branches in the greater St. Louis metropolitan area. As of December 31, 2018 , Reliance had approximately $1.5 billion in assets, $1.1 billion in loans and $1.2 billion in deposits. Co mpletion of the transaction is expected during the second quarter of 2019 and is subject to certain closing conditions, including approval by the shareholders of Reliance, as well as customary regulatory approvals Simultaneously with the closing of the transaction, Reliance Bank is expected to be merged with and into Simmons Bank.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS Southwest Bancorp, Inc. On October 19, 2017, the Company completed the acquisition of Southwest Bancorp, Inc. (“OKSB”) headquartered in Stillwater, Oklahoma, including its wholly-owned bank subsidiary, Bank SNB. The Company issued 14,488,604 shares of its common stock valued at approximately $431.4 million as of October 19, 2017, plus $94.9 million in cash in exchange for all outstanding shares of OKSB common stock. Prior to the acquisition, OKSB conducted banking business from 29 branches located in Texas, Oklahoma, Kansas and Colorado. In addition, OKSB owned a loan production office in Denver, Colorado. Including the effects of the acquisition method accounting adjustments, the Company acquired approximately $2.7 billion in assets, including approximately $2.0 billion in loans (inclusive of loan discounts) and approximately $2.0 billion in deposits. The Company completed the systems conversion and merged Bank SNB into Simmons Bank in May 2018. Goodwill of $229.1 million was recorded as a result of the transaction. The acquisition allowed the Company to enter the Texas, Oklahoma and Colorado banking markets and it also strengthened the Company’s Kansas franchise and its product offerings in the healthcare and real estate industries, all of which gave rise to the goodwill recorded. The goodwill is not deductible for tax purposes. A summary, at fair value, of the assets acquired and liabilities assumed in the OKSB transaction, as of the acquisition date, is as follows: (In thousands) Acquired from OKSB Fair Value Adjustments Fair Value Assets Acquired Cash and due from banks $ 79,517 $ — $ 79,517 Investment securities 485,468 (1,295 ) 484,173 Loans acquired 2,039,524 (43,071 ) 1,996,453 Allowance for loan losses (26,957 ) 26,957 — Foreclosed assets 6,284 (1,127 ) 5,157 Premises and equipment 21,210 5,457 26,667 Bank owned life insurance 28,704 — 28,704 Goodwill 13,545 (13,545 ) — Core deposit intangible 1,933 40,191 42,124 Other intangibles 3,806 — 3,806 Other assets 33,455 (9,141 ) 24,314 Total assets acquired $ 2,686,489 $ 4,426 $ 2,690,915 (In thousands) Acquired from OKSB Fair Value Adjustments Fair Value Liabilities Assumed Deposits: Non-interest bearing transaction accounts $ 485,971 $ — $ 485,971 Interest bearing transaction accounts and savings deposits 869,252 — 869,252 Time deposits 613,345 (2,213 ) 611,132 Total deposits 1,968,568 (2,213 ) 1,966,355 Securities sold under agreement to repurchase 11,256 — 11,256 Other borrowings 347,000 — 347,000 Subordinated debentures 46,393 — 46,393 Accrued interest and other liabilities 17,440 5,364 22,804 Total liabilities assumed 2,390,657 3,151 2,393,808 Equity 295,832 (295,832 ) — Total equity assumed 295,832 (295,832 ) — Total liabilities and equity assumed $ 2,686,489 $ (292,681 ) $ 2,393,808 Net assets acquired 297,107 Purchase price 526,251 Goodwill $ 229,144 During 2018, the Company finalized its analysis of the loans acquired along with other acquired assets and assumed liabilities. The Company’s operating results for 2018 and 2017 include the operating results of the acquired assets and assumed liabilities of OKSB subsequent to the acquisition date. First Texas BHC, Inc. On October 19, 2017, the Company completed the acquisition of First Texas BHC, Inc. (“First Texas”) headquartered in Fort Worth, Texas, including its wholly-owned bank subsidiary, Southwest Bank. The Company issued 12,999,840 shares of its common stock valued at approximately $387.1 million as of October 19, 2017, plus $70.0 million in cash in exchange for all outstanding shares of First Texas common stock. Prior to the acquisition, First Texas operated 15 banking centers, a trust office and a limited service branch in north Texas and a loan production office in Austin, Texas. Including the effects of the acquisition method accounting adjustments, the Company acquired approximately $2.4 billion in assets, including approximately $2.2 billion in loans (inclusive of loan discounts) and approximately $1.9 billion in deposits. The Company completed the systems conversion and merged Southwest Bank into Simmons Bank in February 2018. Goodwill of $240.8 million was recorded as a result of the transaction. The acquisition allowed the Company to enter the Texas banking markets and it also strengthened the Company’s specialty product offerings in the area of SBA lending and trust services, all of which gave rise to the goodwill recorded. The goodwill is not deductible for tax purposes. A summary, at fair value, of the assets acquired and liabilities assumed in the First Texas transaction, as of the acquisition date, is as follows: (In thousands) Acquired from First Texas Fair Value Adjustments Fair Value Assets Acquired Cash and due from banks $ 59,277 $ — $ 59,277 Investment securities 81,114 (596 ) 80,518 Loans acquired 2,246,212 (37,834 ) 2,208,378 Allowance for loan losses (20,864 ) 20,664 (200 ) Premises and equipment 24,864 10,123 34,987 Bank owned life insurance 7,190 — 7,190 Goodwill 37,227 (37,227 ) — Core deposit intangible — 7,328 7,328 Other assets 18,263 11,485 29,748 Total assets acquired $ 2,453,283 $ (26,057 ) $ 2,427,226 Liabilities Assumed Deposits: Non-interest bearing transaction accounts $ 74,410 $ — $ 74,410 Interest bearing transaction accounts and savings deposits 1,683,298 — 1,683,298 Time deposits 124,233 (283 ) 123,950 Total deposits 1,881,941 (283 ) 1,881,658 Securities sold under agreement to repurchase 50,000 — 50,000 Other borrowings 235,000 — 235,000 Subordinated debentures 30,323 589 30,912 Accrued interest and other liabilities 11,727 1,669 13,396 Total liabilities assumed 2,208,991 1,975 2,210,966 Equity 244,292 (244,292 ) — Total equity assumed 244,292 (244,292 ) — Total liabilities and equity assumed $ 2,453,283 $ (242,317 ) $ 2,210,966 Net assets acquired 216,260 Purchase price 457,103 Goodwill $ 240,843 During 2018, the Company finalized its analysis of the loans acquired along with other acquired assets and assumed liabilities. The Company’s operating results for 2018 and 2017 include the operating results of the acquired assets and assumed liabilities of First Texas subsequent to the acquisition date. Summary of Unaudited Pro forma Information The unaudited pro forma information below for the years ended December 31, 2017 and 2016 gives effect to the OKSB and First Texas acquisitions as if the acquisitions had occurred on January 1, 2016. Pro forma earnings for the year ended December 31, 2017 were adjusted to exclude $9.4 million of acquisition-related costs, net of tax, incurred by Simmons during 2017. The pro forma financial information is not necessarily indicative of the results of operations if the acquisitions had been effective as of this date. (In thousands, except per share data) 2017 2016 Revenue (1) $ 654,358 $ 620,461 Net income $ 130,947 $ 136,199 Diluted earnings per share $ 1.43 $ 1.52 _________________________ (1) Net interest income plus non-interest income. Consolidated year-to-date 2017 results included approximately $29.2 million of revenue and $10.5 million of net income attributable to the OKSB acquisition and $27.6 million of revenue and $5.7 million of net income attributable to the First Texas acquisition. Hardeman County Investment Company, Inc. On May 15, 2017, the Company completed the acquisition of Hardeman County Investment Company, Inc. (“Hardeman”), headquartered in Jackson, Tennessee, including its wholly-owned bank subsidiary, First South Bank. The Company issued 1,599,940 shares of its common stock valued at approximately $42.6 million as of May 15, 2017, plus $30.0 million in cash in exchange for all outstanding shares of Hardeman common stock. Prior to the acquisition, Hardeman conducted banking business from 10 branches located in western Tennessee. Including the effects of the acquisition method accounting adjustments, the Company acquired approximately $462.9 million in assets, including approximately $251.6 million in loans (inclusive of loan discounts) and approximately $389.0 million in deposits. The Company completed the systems conversion and merged First South Bank into Simmons Bank in September 2017. As part of the systems conversion, five existing Simmons Bank and First South Bank branches were consolidated or closed. Goodwill of $29.4 million was recorded as a result of the transaction. The merger strengthened the Company’s position in the western Tennessee market, and the Company will be able to achieve cost savings by integrating the two companies and combining accounting, data processing, and other administrative functions, all of which gave rise to the goodwill recorded. The goodwill is not deductible for tax purposes. A summary, at fair value, of the assets acquired and liabilities assumed in the Hardeman transaction, as of the acquisition date, is as follows: (In thousands) Acquired from Hardeman Fair Value Adjustments Fair Value Assets Acquired Cash and due from banks $ 8,001 $ — $ 8,001 Interest bearing balances due from banks - time 1,984 — 1,984 Investment securities 170,654 (285 ) 170,369 Loans acquired 257,641 (5,992 ) 251,649 Allowance for loan losses (2,382 ) 2,382 — Foreclosed assets 1,083 (452 ) 631 Premises and equipment 9,905 1,258 11,163 Bank owned life insurance 7,819 — 7,819 Goodwill 11,485 (11,485 ) — Core deposit intangible — 7,840 7,840 Other intangibles — 830 830 Other assets 2,639 (1 ) 2,638 Total assets acquired $ 468,829 $ (5,905 ) $ 462,924 (In thousands) Acquired from Hardeman Fair Value Adjustments Fair Value Liabilities Assumed Deposits: Non-interest bearing transaction accounts $ 76,555 $ — $ 76,555 Interest bearing transaction accounts and savings deposits 214,872 — 214,872 Time deposits 97,917 (368 ) 97,549 Total deposits 389,344 (368 ) 388,976 Securities sold under agreement to repurchase 17,163 — 17,163 Other borrowings 3,000 — 3,000 Subordinated debentures 6,702 — 6,702 Accrued interest and other liabilities 1,891 1,924 3,815 Total liabilities assumed 418,100 1,556 419,656 Equity 50,729 (50,729 ) — Total equity assumed 50,729 (50,729 ) — Total liabilities and equity assumed $ 468,829 $ (49,173 ) $ 419,656 Net assets acquired 43,268 Purchase price 72,639 Goodwill $ 29,371 During 2018, the Company finalized its analysis of the loans acquired along with other acquired assets and assumed liabilities. The Company’s operating results for 2018 and 2017 include the operating results of the acquired assets and assumed liabilities of Hardeman subsequent to the acquisition date. Citizens National Bank On September 9, 2016, the Company completed the acquisition of Citizens National Bank (“Citizens”), headquartered in Athens, Tennessee. The Company issued 1,671,482 shares of its common stock valued at approximately $41.3 million as of September 9, 2016, plus $35.0 million in cash in exchange for all outstanding shares of Citizens common stock. Prior to the acquisition, Citizens conducted banking business from 9 branches located in east Tennessee. Including the effects of the acquisition method accounting adjustments, the Company acquired approximately $585.1 million in assets, including approximately $340.9 million in loans (inclusive of loan discounts) and approximately $509.9 million in deposits. The Company completed the systems conversion and merged Citizens into Simmons Bank in October 2016. Goodwill of $23.4 million was recorded as a result of the transaction. The merger strengthened the Company’s position in the east Tennessee market and the Company is able to achieve cost savings by integrating the two companies and combining accounting, data processing, and other administrative functions all of which gave rise to the goodwill recorded. The goodwill is deductible for tax purposes. A summary, at fair value, of the assets acquired and liabilities assumed in the Citizens transaction, as of the acquisition date, is as follows: (In thousands) Acquired from Citizens Fair Value Adjustments Fair Value Assets Acquired Cash and due from banks $ 131,467 $ (351 ) $ 131,116 Federal funds sold 10,000 — 10,000 Investment securities 61,987 1 61,988 Loans acquired 350,361 (9,511 ) 340,850 Allowance for loan losses (4,313 ) 4,313 — Foreclosed assets 4,960 (1,518 ) 3,442 Premises and equipment 6,746 1,339 8,085 Bank owned life insurance 6,632 — 6,632 Core deposit intangible — 5,075 5,075 Other intangibles — 591 591 Other assets 17,364 6 17,370 Total assets acquired $ 585,204 $ (55 ) $ 585,149 Liabilities Assumed Deposits: Non-interest bearing transaction accounts $ 109,281 $ — $ 109,281 Interest bearing transaction accounts and savings deposits 204,912 — 204,912 Time deposits 195,664 — 195,664 Total deposits 509,857 — 509,857 Securities sold under agreement to repurchase 13,233 — 13,233 FHLB borrowings 4,000 47 4,047 Accrued interest and other liabilities 3,558 1,530 5,088 Total liabilities assumed 530,648 1,577 532,225 Equity 54,556 (54,556 ) — Total equity assumed 54,556 (54,556 ) — Total liabilities and equity assumed $ 585,204 $ (52,979 ) $ 532,225 Net assets acquired 52,924 Purchase price 76,300 Goodwill $ 23,376 During 2017, the Company finalized its analysis of the loans acquired along with the other acquired assets and assumed liabilities. The Company’s operating results for all periods presented include the operating results of the acquired assets and assumed liabilities of Citizens subsequent to the acquisition date. The following is a description of the methods used to determine the fair values of significant assets and liabilities presented in the acquisitions above. Cash and due from banks, time deposits due from banks and federal funds sold – The carrying amount of these assets is a reasonable estimate of fair value based on the short-term nature of these assets. Investment securities – Investment securities were acquired with an adjustment to fair value based upon quoted market prices if material. Otherwise, the carrying amount of these assets was deemed to be a reasonable estimate of fair value. Loans acquired – Fair values for loans were based on a discounted cash flow methodology that considered factors including the type of loan and related collateral, classification status, fixed or variable interest rate, term of loan and whether or not the loan was amortizing, and current discount rates. The discount rates used for loans are based on current market rates for new originations of comparable loans and include adjustments for liquidity concerns. The discount rate does not include a factor for credit losses as that has been included in the estimated cash flows. Loans were grouped together according to similar characteristics and were treated in the aggregate when applying various valuation techniques. Foreclosed assets – These assets are presented at the estimated present values that management expects to receive when the properties are sold, net of related costs of disposal. Premises and equipment – Bank premises and equipment were acquired with an adjustment to fair value, which represents the difference between the Company’s current analysis of property and equipment values completed in connection with the acquisition and book value acquired. Bank owned life insurance – Bank owned life insurance is carried at its current cash surrender value, which is the most reasonable estimate of fair value. Goodwill – The consideration paid as a result of the acquisition exceeded the fair value of the assets acquired, resulting in an intangible asset, goodwill. Goodwill established prior to the acquisitions, if applicable, was written off. Core deposit intangible – This intangible asset represents the value of the relationships that the acquired banks had with their deposit customers. The fair value of this intangible asset was estimated based on a discounted cash flow methodology that gave appropriate consideration to expected customer attrition rates, cost of the deposit base and the net maintenance cost attributable to customer deposits. Core deposit intangible established prior to the acquisitions, if applicable, was written off. Other intangibles – These intangible assets represent the value of the relationships that Citizens had with their trust customers and Hardeman had with their insurance customers. The fair value of these intangible assets was estimated based on a combination of discounted cash flow methodology and a market valuation approach. Intangible assets for the OKSB acquisition represent mortgage servicing rights. Other intangibles established prior to the acquisitions, if applicable, were written off. Other assets – The fair value adjustment results from certain assets whose value was estimated to be less than book value, such as certain prepaid assets, receivables and other miscellaneous assets. Otherwise, the carrying amount of these assets was deemed to be a reasonable estimate of fair value. Deposits – The fair values used for the demand and savings deposits that comprise the transaction accounts acquired, by definition equal the amount payable on demand at the acquisition date. The Company performed a fair value analysis of the estimated weighted average interest rate of the certificates of deposits compared to the current market rates and recorded a fair value adjustment for the difference when material. Securities sold under agreement to repurchase – The carrying amount of securities sold under agreement to repurchase is a reasonable estimate of fair value based on the short-term nature of these liabilities. FHLB and other borrowings – The fair value of Federal Home Loan Bank and other borrowings is estimated based on borrowing rates currently available to the Company for borrowings with similar terms and maturities. Subordinated debentures – The fair value of subordinated debentures is estimated based on borrowing rates currently available to the Company for borrowings with similar terms and maturities. Due to the floating rate nature of the debenture, the fair value approximates book value as of the date acquired. Accrued interest and other liabilities – The adjustment establishes a liability for unfunded commitments equal to the fair value of that liability at the date of acquisition.

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investment Securities	INVESTMENT SECURITIES The amortized cost and fair value of investment securities that are classified as held-to-maturity (“HTM”) and available-for-sale (“AFS”) are as follows: Years Ended December 31, 2018 2017 (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Estimated Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Estimated Fair Value Held-to-Maturity U.S. Government agencies $ 16,990 $ — $ (49 ) $ 16,941 $ 46,945 $ 7 $ (228 ) $ 46,724 Mortgage-backed securities 13,346 5 (412 ) 12,939 16,132 8 (287 ) 15,853 State and political subdivisions 256,863 3,029 (954 ) 258,938 301,491 5,962 (222 ) 307,231 Other securities 1,995 17 — 2,012 3,490 — — 3,490 Total HTM $ 289,194 $ 3,051 $ (1,415 ) $ 290,830 $ 368,058 $ 5,977 $ (737 ) $ 373,298 Available-for-Sale U.S. Government agencies $ 157,523 $ 518 $ (3,740 ) $ 154,301 $ 141,559 $ 116 $ (1,951 ) $ 139,724 Mortgage-backed securities 1,552,487 3,097 (32,684 ) 1,522,900 1,208,017 246 (20,946 ) 1,187,317 State and political subdivisions 320,142 171 (5,470 ) 314,843 144,642 532 (2,009 ) 143,165 Other securities 157,471 2,251 (14 ) 159,708 118,106 1,206 (1 ) 119,311 Total AFS $ 2,187,623 $ 6,037 $ (41,908 ) $ 2,151,752 $ 1,612,324 $ 2,100 $ (24,907 ) $ 1,589,517 Securities with limited marketability, such as stock in the Federal Reserve Bank and the Federal Home Loan Bank, are carried at cost and are reported as other AFS securities in the table above. Certain investment securities are valued at less than their historical cost. Total fair value of these investments at December 31, 2018 and 2017 , was $1.7 billion and $1.4 billion , which is approximately 70.3% and 73.5% , respectively, of the Company’s combined AFS and HTM investment portfolios. The following table shows the gross unrealized losses and fair value of the Company’s investments with unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at: Less Than 12 Months 12 Months or More Total (In thousands) Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses December 31, 2018 Held-to-Maturity U.S. Government agencies $ 992 $ (2 ) $ 15,948 $ (47 ) $ 16,940 $ (49 ) Mortgage-backed securities — — 12,177 (412 ) 12,177 (412 ) State and political subdivisions 39,149 (208 ) 50,889 (746 ) 90,038 (954 ) Total HTM $ 40,141 $ (210 ) $ 79,014 $ (1,205 ) $ 119,155 $ (1,415 ) Available-for-Sale U.S. Government agencies $ 26,562 $ (221 ) $ 108,636 $ (3,519 ) $ 135,198 $ (3,740 ) Mortgage-backed securities 163,560 (1,146 ) 1,037,679 (31,538 ) 1,201,239 (32,684 ) State and political subdivisions 129,075 (1,406 ) 132,020 (4,064 ) 261,095 (5,470 ) Other securities 65 (13 ) 99 (1 ) 164 (14 ) Total AFS $ 319,262 $ (2,786 ) $ 1,278,434 $ (39,122 ) $ 1,597,696 $ (41,908 ) December 31, 2017 Held-to-Maturity U.S. Government agencies $ 11,961 $ (6 ) $ 32,778 $ (222 ) $ 44,739 $ (228 ) Mortgage-backed securities 5,471 (47 ) 8,946 (240 ) 14,417 (287 ) State and political subdivisions 40,299 (198 ) 1,887 (24 ) 42,186 (222 ) Total HTM $ 57,731 $ (251 ) $ 43,611 $ (486 ) $ 101,342 $ (737 ) Available-for-Sale U.S. Government agencies $ 91,988 $ (921 ) $ 25,742 $ (1,030 ) $ 117,730 $ (1,951 ) Mortgage-backed securities 510,770 (4,516 ) 609,329 (16,430 ) 1,120,099 (20,946 ) State and political subdivisions 25,049 (202 ) 75,404 (1,807 ) 100,453 (2,009 ) Other securities — — 99 (1 ) 99 (1 ) Total AFS $ 627,807 $ (5,639 ) $ 710,574 $ (19,268 ) $ 1,338,381 $ (24,907 ) The declines reflected in the preceding table primarily resulted from the rate for these investments yielding less than current market rates. Based on evaluation of available evidence, management believes the declines in fair value for these securities are temporary. Management does not have the intent to sell these securities and management believes it is more likely than not the Company will not have to sell these securities before recovery of their amortized cost basis less any current period credit losses. Declines in the fair value of HTM and AFS securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses. In estimating other-than-temporary impairment losses, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, and (iii) the intent and ability of the Company to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in fair value. Management has the ability and intent to hold the securities classified as HTM until they mature, at which time the Company expects to receive full value for the securities. Furthermore, as of December 31, 2018 , management also had the ability and intent to hold the securities classified as AFS for a period of time sufficient for a recovery of cost. The unrealized losses are largely due to increases in market interest rates over the yields available at the time the underlying securities were purchased. The fair value is expected to recover as the bonds approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality. Accordingly, as of December 31, 2018 , management believes the impairments detailed in the table above are temporary. Should the impairment of any of these securities become other than temporary, the cost basis of the investment will be reduced and the resulting loss recognized in net income in the period the other-than-temporary impairment is identified. Income earned on securities for the years ended December 31, 2018 , 2017 and 2016 , is as follows: (In thousands) 2018 2017 2016 Taxable: Held-to-maturity $ 2,157 $ 2,521 $ 3,778 Available-for-sale 40,926 25,996 17,928 Non-taxable: Held-to-maturity 7,424 8,693 10,641 Available-for-sale 6,811 2,905 1,132 Total $ 57,318 $ 40,115 $ 33,479 The amortized cost and estimated fair value by maturity of securities are shown in the following table. Securities are classified according to their contractual maturities without consideration of principal amortization, potential prepayments or call options. Accordingly, actual maturities may differ from contractual maturities. Held-to-Maturity Available-for-Sale (In thousands) Amortized Cost Fair Value Amortized Cost Fair Value One year or less $ 29,579 $ 29,515 $ 120 $ 119 After one through five years 60,564 60,514 35,518 34,923 After five through ten years 88,770 88,971 39,426 39,360 After ten years 96,935 98,891 407,815 400,011 Securities not due on a single maturity date 13,346 12,939 1,552,487 1,522,900 Other securities (no maturity) — — 152,257 154,439 Total $ 289,194 $ 290,830 $ 2,187,623 $ 2,151,752 The carrying value, which approximates the fair value, of securities pledged as collateral, to secure public deposits and for other purposes, amounted to $1.0 billion at December 31, 2018 and $1.2 billion at December 31, 2017 . There were $65,000 of gross realized gains and $4,000 of gross realized losses from the sale of securities during the year ended December 31, 2018 . There were $2.4 million of gross realized gains and $1.3 million of gross realized losses from the sale of securities during the year ended December 31, 2017 . There were $5.8 million of gross realized gains and no gross realized losses from the sale of securities during the year ended December 31, 2016 . The income tax expense/benefit related to security gains/losses was 26.135% of the gross amounts in 2018 and 39.225% in 2017 and 2016. The state and political subdivision debt obligations are predominately non-rated bonds representing small issuances, primarily in Arkansas, Missouri, Oklahoma, Tennessee and Texas issues, which are evaluated on an ongoing basis.

Other Assets and Other Liabilit

Other Assets and Other Liabilities Held for Sale	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Other Assets and Other Liabilities Held for Sale	OTHER ASSETS AND OTHER LIABILITIES HELD FOR SALE In August 2017, the Company, through its bank subsidiary, Simmons Bank, acquired the stock of Heartland Bank (“Heartland”) at a public auction held to satisfy certain indebtedness of Heartland’s former holding company, Rock Bancshares, Inc. In March 2018, Heartland sold $141.0 million of branches and loans, as well as $154.6 million of deposits and other liabilities. As of December 31, 2018 , other assets held for sale of $1.8 million and other liabilities held for sale of $162,000 related to Heartland, both recorded at fair value, remained at the Company. The Company will continue to work through the disposition of Heartland’s few remaining assets.

Loans and Allowance for Loan Lo

Loans and Allowance for Loan Losses	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Loans and Allowance for Loan Losses	LOANS AND ALLOWANCE FOR LOAN LOSSES At December 31, 2018 , the Company’s loan portfolio was $11.72 billion , compared to $10.78 billion at December 31, 2017 . The various categories of loans are summarized as follows: (In thousands) 2018 2017 Consumer: Credit cards $ 204,173 $ 185,422 Other consumer 201,297 280,094 Total consumer 405,470 465,516 Real estate: Construction 1,300,723 614,155 Single family residential 1,440,443 1,094,633 Other commercial 3,225,287 2,530,824 Total real estate 5,966,453 4,239,612 Commercial: Commercial 1,774,909 825,217 Agricultural 164,514 148,302 Total commercial 1,939,423 973,519 Other 119,042 26,962 Loans 8,430,388 5,705,609 Loans acquired, net of discount and allowance (1) 3,292,783 5,074,076 Total loans $ 11,723,171 $ 10,779,685 _________________________ (1) See Note 6, Loans Acquired, for segregation of loans acquired by loan class. Loan Origination/Risk Management – The Company seeks to manage its credit risk by diversifying its loan portfolio, determining that borrowers have adequate sources of cash flow for loan repayment without liquidation of collateral; obtaining and monitoring collateral; providing an adequate allowance for loans losses by regularly reviewing loans through the internal loan review process. The loan portfolio is diversified by borrower, purpose and industry. The Company seeks to use diversification within the loan portfolio to reduce its credit risk, thereby minimizing the adverse impact on the portfolio, if weaknesses develop in either the economy or a particular segment of borrowers. Collateral requirements are based on credit assessments of borrowers and may be used to recover the debt in case of default. Furthermore, a factor that influenced the Company’s judgment regarding the allowance for loan losses consists of a nine-year historical loss average segregated by each primary loan sector. On an annual basis, historical loss rates are calculated for each sector. Consumer – The consumer loan portfolio consists of credit card loans and other consumer loans. Credit card loans are diversified by geographic region to reduce credit risk and minimize any adverse impact on the portfolio. Although they are regularly reviewed to facilitate the identification and monitoring of creditworthiness, credit card loans are unsecured loans, making them more susceptible to be impacted by economic downturns resulting in increasing unemployment. Other consumer loans include direct and indirect installment loans and overdrafts. Loans in this portfolio segment are sensitive to unemployment and other key consumer economic measures. Real estate – The real estate loan portfolio consists of construction loans, single family residential loans and commercial loans. Construction and development loans (“C&D”) and commercial real estate loans (“CRE”) can be particularly sensitive to valuation of real estate. Commercial real estate cycles are inevitable. The long planning and production process for new properties and rapid shifts in business conditions and employment create an inherent tension between supply and demand for commercial properties. While general economic trends often move individual markets in the same direction over time, the timing and magnitude of changes are determined by other forces unique to each market. CRE cycles tend to be local in nature and longer than other credit cycles. Factors influencing the CRE market are traditionally different from those affecting residential real estate markets; thereby making predictions for one market based on the other difficult. Additionally, submarkets within commercial real estate – such as office, industrial, apartment, retail and hotel – also experience different cycles, providing an opportunity to lower the overall risk through diversification across types of CRE loans. Management realizes that local demand and supply conditions will also mean that different geographic areas will experience cycles of different amplitude and length. The Company monitors these loans closely. Commercial – The commercial loan portfolio includes commercial and agricultural loans, representing loans to commercial customers and farmers for use in normal business or farming operations to finance working capital needs, equipment purchases or other expansion projects. Collection risk in this portfolio is driven by the creditworthiness of the underlying borrowers, particularly cash flow from customers’ business or farming operations. The Company continues its efforts to keep loan terms short, reducing the negative impact of upward movement in interest rates. Term loans are generally set up with one or three year balloons, and the Company has instituted a pricing mechanism for commercial loans. It is standard practice to require personal guaranties on commercial loans for closely-held or limited liability entities. Nonaccrual and Past Due Loans – Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due. Loans are placed on nonaccrual status when, in management’s opinion, the borrower may be unable to meet payment obligations as they become due, as well as when required by regulatory provisions. Loans may be placed on nonaccrual status regardless of whether or not such loans are considered past due. When interest accrual is discontinued, all unpaid accrued interest is reversed. Interest income is subsequently recognized only to the extent cash payments are received in excess of principal due. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured. Nonaccrual loans, excluding loans acquired, at December 31, 2018 and 2017 , segregated by class of loans, are as follows: (In thousands) 2018 2017 Consumer: Credit cards $ 296 $ 170 Other consumer 2,159 4,605 Total consumer 2,455 4,775 Real estate: Construction 1,269 2,242 Single family residential 11,939 13,431 Other commercial 7,205 16,054 Total real estate 20,413 31,727 Commercial: Commercial 10,049 6,980 Agricultural 1,284 2,160 Total commercial 11,333 9,140 Total $ 34,201 $ 45,642 An age analysis of past due loans, excluding loans acquired, segregated by class of loans, is as follows: (In thousands) Gross 30-89 Days Past Due 90 Days or More Past Due Total Past Due Current Total Loans 90 Days Past Due & Accruing December 31, 2018 Consumer: Credit cards $ 1,033 $ 506 $ 1,539 $ 202,634 $ 204,173 $ 209 Other consumer 4,264 896 5,160 196,137 201,297 4 Total consumer 5,297 1,402 6,699 398,771 405,470 213 Real estate: Construction 533 308 841 1,299,882 1,300,723 — Single family residential 7,769 4,127 11,896 1,428,547 1,440,443 — Other commercial 3,379 2,773 6,152 3,219,135 3,225,287 — Total real estate 11,681 7,208 18,889 5,947,564 5,966,453 — Commercial: Commercial 4,472 5,105 9,577 1,765,332 1,774,909 11 Agricultural 467 1,055 1,522 162,992 164,514 — Total commercial 4,939 6,160 11,099 1,928,324 1,939,423 11 Other — — — 119,042 119,042 — Total $ 21,917 $ 14,770 $ 36,687 $ 8,393,701 $ 8,430,388 $ 224 December 31, 2017 Consumer: Credit cards $ 707 $ 672 $ 1,379 $ 184,043 $ 185,422 $ 332 Other consumer 5,009 3,298 8,307 271,787 280,094 10 Total consumer 5,716 3,970 9,686 455,830 465,516 342 Real estate: Construction 411 1,210 1,621 612,534 614,155 — Single family residential 8,071 6,460 14,531 1,080,102 1,094,633 1 Other commercial 2,388 8,031 10,419 2,520,405 2,530,824 — Total real estate 10,870 15,701 26,571 4,213,041 4,239,612 1 Commercial: Commercial 1,523 6,125 7,648 817,569 825,217 — Agricultural 50 2,120 2,170 146,132 148,302 — Total commercial 1,573 8,245 9,818 963,701 973,519 — Other — — — 26,962 26,962 — Total $ 18,159 $ 27,916 $ 46,075 $ 5,659,534 $ 5,705,609 $ 343 Impaired Loans – A loan is considered impaired when it is probable that the Company will not receive all amounts due according to the contractual terms of the loans, including scheduled principal and interest payments. This includes loans that are delinquent 90 days or more, nonaccrual loans and certain other loans identified by management. Certain other loans identified by management consist of performing loans with specific allocations of the allowance for loan losses. Impaired loans are carried at the present value of estimated future cash flows using the loan’s existing rate, or the fair value of the collateral if the loan is collateral dependent. Impairment is evaluated in total for smaller-balance loans of a similar nature and on an individual loan basis for other loans. Impaired loans, or portions thereof, are charged-off when deemed uncollectible. Impaired loans, net of government guarantees and excluding loans acquired, segregated by class of loans, are as follows: (In thousands) Unpaid Contractual Principal Balance Recorded Investment With No Allowance Recorded Investment With Allowance Total Recorded Investment Related Allowance Average Investment in Impaired Loans Interest Income Recognized December 31, 2018 Consumer: Credit cards $ 296 $ 296 $ — $ 296 $ — $ 266 $ 85 Other consumer 2,311 2,159 — 2,159 — 3,719 112 Total consumer 2,607 2,455 — 2,455 — 3,985 197 Real estate: Construction 1,344 784 485 1,269 211 1,651 50 Single family residential 12,906 11,468 616 12,084 36 13,257 399 Other commercial 8,434 5,442 5,458 10,900 — 13,608 410 Total real estate 22,684 17,694 6,559 24,253 247 28,516 859 Commercial: Commercial 10,361 7,254 4,628 11,882 437 10,003 301 Agricultural 2,419 1,180 — 1,180 — 1,412 43 Total commercial 12,780 8,434 4,628 13,062 437 11,415 344 Total $ 38,071 $ 28,583 $ 11,187 $ 39,770 $ 684 $ 43,916 $ 1,400 December 31, 2017 Consumer: Credit cards $ 170 $ 170 $ — $ 170 $ — $ 268 $ 47 Other consumer 4,755 4,605 — 4,605 — 3,089 106 Total consumer 4,925 4,775 — 4,775 — 3,357 153 Real estate: Construction 2,522 1,347 895 2,242 249 2,711 93 Single family residential 14,347 12,725 706 13,431 53 12,904 443 Other commercial 22,308 6,732 9,133 15,865 36 18,624 639 Total real estate 39,177 20,804 10,734 31,538 338 34,239 1,175 Commercial: Commercial 9,954 4,306 2,269 6,575 — 11,670 400 Agricultural 3,278 1,035 — 1,035 — 1,522 52 Total commercial 13,232 5,341 2,269 7,610 — 13,192 452 Total $ 57,334 $ 30,920 $ 13,003 $ 43,923 $ 338 $ 50,788 $ 1,780 At December 31, 2018 and 2017 , impaired loans, net of government guarantees and excluding loans acquired, totaled $39.8 million and $43.9 million , respectively. Allocations of the allowance for loan losses relative to impaired loans were $684,000 and $338,000 at December 31, 2018 and 2017 , respectively. Approximately $1.4 million , $1.8 million and $1.6 million of interest income was recognized on average impaired loans of $43.9 million , $50.8 million and $36.0 million for 2018 , 2017 and 2016 , respectively. Interest recognized on impaired loans on a cash basis during 2018 , 2017 and 2016 was not material. Included in certain impaired loan categories are troubled debt restructurings (“TDRs”). When the Company restructures a loan to a borrower that is experiencing financial difficulty and grants a concession that it would not otherwise consider, a “troubled debt restructuring” results and the Company classifies the loan as a TDR. The Company grants various types of concessions, primarily interest rate reduction and/or payment modifications or extensions, with an occasional forgiveness of principal. Under ASC Topic 310-10-35 – Subsequent Measurement , a TDR is considered to be impaired, and an impairment analysis must be performed. The Company assesses the exposure for each modification, either by collateral discounting or by calculation of the present value of future cash flows, and determines if a specific allocation to the allowance for loan losses is needed. Once an obligation has been restructured because of such credit problems, it continues to be considered a TDR until paid in full; or, if an obligation yields a market interest rate and no longer has any concession regarding payment amount or amortization, then it is not considered a TDR at the beginning of the calendar year after the year in which the improvement takes place. The Company returns TDRs to accrual status only if (1) all contractual amounts due can reasonably be expected to be repaid within a prudent period, and (2) repayment has been in accordance with the contract for a sustained period, typically at least six months. The following table presents a summary of troubled debt restructurings, excluding loans acquired, segregated by class of loans. Accruing TDR Loans Nonaccrual TDR Loans Total TDR Loans (Dollars in thousands) Number Balance Number Balance Number Balance December 31, 2018 Real estate: Construction — $ — 3 $ 485 3 $ 485 Single-family residential 6 230 10 616 16 846 Other commercial 2 3,306 2 1,027 4 4,333 Total real estate 8 3,536 15 2,128 23 5,664 Commercial: Commercial 4 2,833 6 718 10 3,551 Total commercial 4 2,833 6 718 10 3,551 Total 12 $ 6,369 21 $ 2,846 33 $ 9,215 December 31, 2017 Real estate: Construction — $ — 1 $ 420 1 $ 420 Single-family residential 4 141 15 954 19 1,095 Other commercial 4 4,322 5 3,712 9 8,034 Total real estate 8 4,463 21 5,086 29 9,549 Commercial: Commercial 5 2,644 6 745 11 3,389 Total commercial 5 2,644 6 745 11 3,389 Total 13 $ 7,107 27 $ 5,831 40 $ 12,938 The following table presents loans that were restructured as TDRs during the years ended December 31, 2018 and 2017 , excluding loans acquired, segregated by class of loans. Modification Type (Dollars in thousands) Number of Loans Balance Prior to TDR Balance at December 31, Change in Maturity Date Change in Rate Financial Impact on Date of Restructure Year Ended December 31, 2018 Consumer: Other consumer 1 $ 91 $ 91 $ 91 $ — $ — Total consumer 1 91 91 91 — — Real estate: Construction 1 99 98 98 — — Single-family residential 1 61 62 62 — — Other commercial 2 392 390 390 — 212 Total real estate 4 552 550 550 — 212 Commercial: Commercial 3 2,363 2,358 2,358 — 190 Total commercial 3 2,363 2,358 2,358 — 190 Total 8 $ 3,006 $ 2,999 $ 2,999 $ — $ 402 Year Ended December 31, 2017 Real estate: Construction 1 $ 456 $ 456 $ 456 $ — $ — Single-family residential 1 139 130 130 — — Other commercial 3 7,715 7,715 7,715 — 33 Total real estate 5 8,310 8,301 8,301 — 33 Commercial: Commercial 11 2,691 2,604 2,565 39 — Total commercial 11 2,691 2,604 2,565 39 — Total 16 $ 11,001 $ 10,905 $ 10,866 $ 39 $ 33 During the year ended December 31, 2018 , the Company modified eight loans with a total recorded investment of $3.0 million prior to modification which were deemed troubled debt restructuring. The restructured loans were modified by deferring amortized principal payments, changing the maturity date and requiring interest only payments for a period of up to 12 months. A specific reserve was not determined necessary for these loans based on the fair value of the collateral. Also, there was $402,000 immediate financial impact from the restructuring of these loans due to specific loan loss reserves for these loans. During the year ended December 31, 2018 , seven of the previously restructured loans with prior balances of $655,000 were paid off. During year ended December 31, 2017 , the Company modified sixteen loans with a total recorded investment of $11.0 million prior to modification which were deemed troubled debt restructuring. The restructured loans were modified by deferring amortized principal payments, changing the maturity date and requiring interest only payments for a period of up to 12 months. Based on the fair value of the collateral, a specific reserve of $26,000 was determined necessary for these loans. Also, the financial impact from the restructuring of these loans was $33,000 . During the year ended December 31, 2017 , thirteen of the previously restructured loans with prior balances of $1.2 million were paid off. There were two commercial real estate loans for which a payment default occurred during the year ended December 31, 2018 , that had been modified as a TDR within 12 months or less of the payment default, excluding loans acquired. A charge off of approximately $92,400 was recorded for these loans and assets valued at $2,169,300 were transferred to OREO. Also, there was one single-family residential loan for which a payment default occurred during the year ended December 31, 2018 , that had been modified as a TDR within 12 months or less of the payment default, excluding loans acquired. A charge off of approximately $26,500 was recorded for this loan. The Company defines a payment default as a payment received more than 90 days after its due date. During the year ended December 31, 2017 , there was one commercial real estate loan for which a payment default occurred that had been modified as a TDR within 12 months or less of the payment default. A charge off of $440,000 was recorded for this loan. Also, there was one single-family residential loan for which a payment default occurred that had been modified as a TDR within 12 months or less of the payment default for which formal foreclosure proceedings were in process. In addition to the TDRs that occurred during the periods provided in the preceding tables, the Company had TDRs with pre-modification loan balances of $2,288,000 at December 31, 2018 for which OREO was received in full or partial satisfaction of the loans. There were no TDRs at December 31, 2017 for which OREO was received in full or partial satisfaction of the loans. At December 31, 2018 and 2017 , the Company had $3,899,000 and $5,057,000 , respectively, of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings are in process. At December 31, 2018 and 2017 , the Company had $3,530,000 and $3,828,000 , respectively, of OREO secured by residential real estate properties. Credit Quality Indicators – As part of the on-going monitoring of the credit quality of the Company’s loan portfolio, management tracks certain credit quality indicators including trends related to (i) the weighted-average risk rating of commercial and real estate loans, (ii) the level of classified commercial and real estate loans, (iii) net charge-offs, (iv) non-performing loans (see details above) and (v) the general economic conditions in the States of Arkansas, Colorado, Kansas, Missouri, Oklahoma, Tennessee and Texas. The Company utilizes a risk rating matrix to assign a risk rate to each of its commercial and real estate loans. Loans are rated on a scale of 1 to 8. A description of the general characteristics of the 8 risk ratings is as follows: • Risk Rate 1 – Pass (Excellent) – This category includes loans which are virtually free of credit risk. Borrowers in this category represent the highest credit quality and greatest financial strength. • Risk Rate 2 – Pass (Good) - Loans under this category possess a nominal risk of default. This category includes borrowers with strong financial strength and superior financial ratios and trends. These loans are generally fully secured by cash or equivalents (other than those rated “excellent”). • Risk Rate 3 – Pass (Acceptable – Average) - Loans in this category are considered to possess a normal level of risk. Borrowers in this category have satisfactory financial strength and adequate cash flow coverage to service debt requirements. If secured, the perfected collateral should be of acceptable quality and within established borrowing parameters. • Risk Rate 4 – Pass (Monitor) - Loans in the Watch (Monitor) category exhibit an overall acceptable level of risk, but that risk may be increased by certain conditions, which represent “red flags”. These “red flags” require a higher level of supervision or monitoring than the normal “Pass” rated credit. The borrower may be experiencing these conditions for the first time, or it may be recovering from weakness, which at one time justified a higher rating. These conditions may include: weaknesses in financial trends; marginal cash flow; one-time negative operating results; non-compliance with policy or borrowing agreements; poor diversity in operations; lack of adequate monitoring information or lender supervision; questionable management ability/stability. • Risk Rate 5 – Special Mention - A loan in this category 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 the institution’s credit position at some future date. Special Mention loans are not adversely classified (although they are “criticized”) and do not expose an institution to sufficient risk to warrant adverse classification. Borrowers may be experiencing adverse operating trends, or an ill-proportioned balance sheet. Non-financial characteristics of a Special Mention rating may include management problems, pending litigation, a non-existent, or ineffective loan agreement or other material structural weakness, and/or other significant deviation from prudent lending practices. • Risk Rate 6 – Substandard - A Substandard loan is inadequately protected by the current sound worth and paying capacity of the borrower 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. The loans are characterized by the distinct possibility that the Company will sustain some loss if the deficiencies are not corrected. This does not imply ultimate loss of the principal, but may involve burdensome administrative expenses and the accompanying cost to carry the loan. • Risk Rate 7 – Doubtful - A loan classified Doubtful has all the weaknesses inherent in a substandard loan except that the weaknesses make collection or liquidation in full (on the basis of currently existing facts, conditions, and values) highly questionable and improbable. Doubtful borrowers are usually in default, lack adequate liquidity, or capital, and lack the resources necessary to remain an operating entity. The possibility of loss is extremely high, but because of specific pending events that may strengthen the asset, its classification as loss is deferred. Pending factors include: proposed merger or acquisition; liquidation procedures; capital injection; perfection of liens on additional collateral; and refinancing plans. Loans classified as Doubtful are placed on nonaccrual status. • Risk Rate 8 – Loss - Loans classified Loss are considered uncollectible and of such little value that their continuance as bankable assets is not warranted. This classification does not mean that the loans has absolutely no recovery or salvage value, but rather it is not practical or desirable to defer writing off this basically worthless loan, even though partial recovery may be affected in the future. Borrowers in the Loss category are often in bankruptcy, have formally suspended debt repayments, or have otherwise ceased normal business operations. Loans should be classified as Loss and charged-off in the period in which they become uncollectible. Loans acquired are evaluated using this internal grading system. Loans acquired are evaluated individually and include purchased credit impaired loans of $4.1 million and $17.1 million that are accounted for under ASC Topic 310-30 and are classified as substandard (Risk Rating 6) as of December 31, 2018 and 2017 , respectively. Of the remaining loans acquired and accounted for under ASC Topic 310-20, $50.4 million and $76.3 million were classified (Risk Ratings 6, 7 and 8 – see classified loans discussion below) at December 31, 2018 and 2017 , respectively. Purchased credit impaired loans are loans that showed evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all amounts contractually owed. Their fair value was initially based on the estimate of cash flows, both principal and interest, expected to be collected or estimated collateral values if cash flows are not estimable, discounted at prevailing market rates of interest. The difference between the undiscounted cash flows expected at acquisition and the fair value at acquisition is recognized as interest income on a level-yield method over the life of the loan. Contractually required payments for interest and principal that exceed the undiscounted cash flows expected at acquisition are not recognized as a yield adjustment. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairment. Classified loans for the Company include loans in Risk Ratings 6, 7 and 8. Loans may be classified, but not considered impaired, due to one of the following reasons: (1) The Company has established minimum dollar amount thresholds for loan impairment testing. Loans rated 6 – 8 that fall under the threshold amount are not tested for impairment and therefore are not included in impaired loans. (2) Of the loans that are above the threshold amount and tested for impairment, after testing, some are considered to not be impaired and are not included in impaired loans. Total classified loans, excluding loans accounted for under ASC Topic 310-30, were $119.0 million and $175.6 million as of December 31, 2018 and 2017 , respectively. The following table presents a summary of loans by credit risk rating, segregated by class of loans. (In thousands) Risk Rate 1-4 Risk Rate 5 Risk Rate 6 Risk Rate 7 Risk Rate 8 Total December 31, 2018 Consumer: Credit cards $ 203,667 $ — $ 506 $ — $ — $ 204,173 Other consumer 198,840 — 2,457 — — 201,297 Total consumer 402,507 — 2,963 — — 405,470 Real estate: Construction 1,296,988 1,910 1,825 — — 1,300,723 Single family residential 1,420,052 1,628 18,528 235 — 1,440,443 Other commercial 3,193,289 17,169 14,829 — — 3,225,287 Total real estate 5,910,329 20,707 35,182 235 — 5,966,453 Commercial: Commercial 1,742,002 8,357 24,550 — — 1,774,909 Agricultural 162,824 75 1,615 — — 164,514 Total commercial 1,904,826 8,432 26,165 — — 1,939,423 Other 119,042 — — — — 119,042 Loans acquired 3,187,083 51,255 54,097 348 — 3,292,783 Total $ 11,523,787 $ 80,394 $ 118,407 $ 583 $ — $ 11,723,171 (In thousands) Risk Rate 1-4 Risk Rate 5 Risk Rate 6 Risk Rate 7 Risk Rate 8 Total December 31, 2017 Consumer: Credit cards $ 184,920 $ — $ 502 $ — $ — $ 185,422 Other consumer 275,160 — 4,934 — — 280,094 Total consumer 460,080 — 5,436 — — 465,516 Real estate: Construction 603,126 5,795 5,218 16 — 614,155 Single family residential 1,066,902 3,954 23,490 287 — 1,094,633 Other commercial 2,480,293 19,581 30,950 — — 2,530,824 Total real estate 4,150,321 29,330 59,658 303 — 4,239,612 Commercial: Commercial 736,377 74,254 14,402 50 134 825,217 Agricultural 146,065 24 2,190 23 — 148,302 Total commercial 882,442 74,278 16,592 73 134 973,519 Other 26,962 — — — — 26,962 Loans acquired 4,918,570 62,128 93,378 — — 5,074,076 Total $ 10,438,375 $ 165,736 $ 175,064 $ 376 $ 134 $ 10,779,685 Net (charge-offs)/recoveries for the years ended December 31, 2018 and 2017 , excluding loans acquired, segregated by class of loans, were as follows: (In thousands) 2018 2017 Consumer: Credit cards $ (3,046 ) $ (2,884 ) Other consumer (6,080 ) (1,528 ) Total consumer (9,126 ) (4,412 ) Real estate: Construction (1,775 ) 100 Single family residential (494 ) (1,045 ) Other commercial (2,645 ) (6,054 ) Total real estate (4,914 ) (6,999 ) Commercial: Commercial (5,878 ) (7,734 ) Agricultural — — Total commercial (5,878 ) (7,734 ) Total $ (19,918 ) $ (19,145 ) Allowance for Loan Losses Allowance for Loan Losses – The allowance for loan losses is a reserve established through a provision for loan losses charged to expense, which represents management’s best estimate of probable losses that have been incurred within the existing portfolio of loans. The allowance, in the judgment of management, is necessary to reserve for estimated loan losses and risks inherent in the loan portfolio. The Company’s allowance for loan loss methodology includes allowance allocations calculated in accordance with ASC Topic 310-10, Receivables , and allowance allocations calculated in accordance with ASC Topic 450-20, Loss Contingencies . Accordingly, the methodology is based on the Company’s internal grading system, specific impairment analysis, qualitative and quantitative factors. As mentioned above, allocations to the allowance for loan losses are categorized as either specific allocations or general allocations. A loan is considered impaired when it is probable that the Company will not receive all amounts due according to the contractual terms of the loan, including scheduled principal and interest payments. For a collateral dependent loan, the Company’s evaluation process includes a valuation by appraisal or other collateral analysis. This valuation is compared to the remaining outstanding principal balance of the loan. If a loss is determined to be probable, the loss is included in the allowance for loan losses as a specific allocation. If the loan is not collateral dependent, the measurement of loss is based on the difference between the expected and contractual future cash flows of the loan. The general allocation is calculated monthly based on management’s assessment of several factors such as (1) historical loss experience based on volumes and types, (2) volume and trends in delinquencies and nonaccruals, (3) lending policies and procedures including those for loan losses, collections and recoveries, (4) national, state and local economic trends and conditions, (5) external factors and pressure from competition, (6)the experience, ability and depth of lending management and staff, (7) seasoning of new products obtained and new markets entered through acquisition and (8) other factors and trends that will affect specific loans and categories of loans. The Company establishes general allocations for each major loan category. This category also includes allocations to loans which are collectively evaluated for loss such as credit cards, one-to-four family owner occupied residential real estate loans and other consumer loans. The following table details activity in the allowance for loan losses by portfolio segment for the years ended December 31, 2018 and 2017 . Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. (In thousands) Commercial Real Estate Credit Card Other Consumer and Other Total December 31, 2018 Balance, beginning of year (2) $ 7,007 $ 27,281 $ 3,784 $ 3,596 $ 41,668 Provision for loan losses (1) 19,385 7,376 3,185 4,903 34,849 Charge-offs (6,623 ) (5,905 ) (4,051 ) (6,637 ) (23,216 ) Recoveries 745 991 1,005 557 3,298 Net charge-offs (5,878 ) (4,914 ) (3,046 ) (6,080 ) (19,918 ) Balance, end of year (2) $ 20,514 $ 29,743 $ 3,923 $ 2,419 $ 56,599 Period-end amount allocated to: Loans individually evaluated for impairment $ 437 $ 247 $ — $ — $ 684 Loans collectively evaluated for impairment 20,077 29,496 3,923 2,419 55,915 Balance, end of year (2) $ 20,514 $ 29,743 $ 3,923 $ 2,419 $ 56,599 December 31, 2017 Balance, beginning of year (2) $ 7,739 $ 21,817 $ 3,779 $ 2,951 $ 36,286 Provision for loan losses (1) 7,002 12,463 2,889 2,173 24,527 Charge-offs (7,837 ) (7,989 ) (3,905 ) (3,767 ) (23,498 ) Recoveries 103 990 1,021 2,239 4,353 Net charge-offs (7,734 ) (6,999 ) (2,884 ) (1,528 ) (19,145 ) Balance, end of year (2) $ 7,007 $ 27,281 $ 3,784 $ 3,596 $ 41,668 Period-end amount allocated to: Loans individually evaluated for impairment $ — $ 338 $ — $ — $ 338 Loans collectively evaluated for impairment 7,007 26,943 3,784 3,596 41,330 Balance, end of year (2) $ 7,007 $ 27,281 $ 3,784 $ 3,596 $ 41,668 _________________________ (1) Provision for loan losses of $3,299,000 attributable to loans acquired was excluded from this table for the year ended December 31, 2018 (total provision for loan losses for the year ended December 31, 2018 was $38,148,000 ). There were $3,622,000 in charge-offs for loans acquired during the year ended December 31, 2018 resulting in an ending balance in the allowance related to loans acquired of $95,000 . Provision for loan losses of $1,866,000 attributable to loans acquired was excluded from this table for the year ended December 31, 2017 (total provision for loan losses for the year ended December 31, 2017 was $26,393,000 ). There were $2,400,000 in charge-offs for loans acquired during the year ended December 31, 2017 resulting in an ending balance in the allowance related to loans

Loans Acquired

Loans Acquired	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Loans Acquired	LOANS ACQUIRED During the fourth quarter of 2017, the Company evaluated $1.985 billion of net loans ( $2.021 billion gross loans less $36.3 million discount) purchased in conjunction with the acquisition of OKSB, described in Note 2, Acquisitions, in accordance with the provisions of ASC Topic 310-20, Nonrefundable Fees and Other Costs . The fair value discount is being accreted into interest income over the weighted average life of the loans using a constant yield method. These loans are not considered to be impaired loans. The Company evaluated the remaining $11.4 million of net loans ( $18.1 million gross loans less $6.7 million discount) purchased in conjunction with the acquisition of OKSB for impairment in accordance with the provisions of ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality . Purchased loans are considered impaired if there is evidence of credit deterioration since origination and if it is probable that not all contractually required payments will be collected. Also during the fourth quarter of 2017, the Company evaluated $2.208 billion of net loans ( $2.246 billion gross loans less $37.8 million discount) purchased in conjunction with the acquisition of First Texas, described in Note 2, Acquisitions, in accordance with the provisions of ASC Topic 310-20, Nonrefundable Fees and Other Costs . The fair value discount is being accreted into interest income over the weighted average life of the loans using a constant yield method. These loans are not considered to be impaired loans. During the second quarter of 2017, the Company evaluated $249.2 million of net loans ( $254.2 million gross loans less $5.0 million discount) purchased in conjunction with the acquisition of Hardeman, described in Note 2, Acquisitions, in accordance with the provisions of ASC Topic 310-20, Nonrefundable Fees and Other Costs . The fair value discount is being accreted into interest income over the weighted average life of the loans using a constant yield method. These loans are not considered to be impaired loans. The Company evaluated the remaining $2.4 million of net loans ( $3.4 million gross loans less $990,000 discount) purchased in conjunction with the acquisition of Hardeman for impairment in accordance with the provisions of ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality . During the third quarter of 2016, the Company evaluated $340.1 million of net loans ( $348.8 million gross loans less $8.7 million discount) purchased in conjunction with the acquisition of Citizens, described in Note 2, Acquisitions, in accordance with the provisions of ASC Topic 310-20, Nonrefundable Fees and Other Costs . The fair value discount is being accreted into interest income over the weighted average life of the loans using a constant yield method. These loans are not considered to be impaired loans. The Company evaluated the remaining $757,000 of net loans ( $1.6 million gross loans less $848,000 discount) purchased in conjunction with the acquisition of Citizens for impairment in accordance with the provisions of ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality . See Note 2, Acquisitions, for further discussion of loans acquired. The following table reflects the carrying value of all loans acquired as of December 31, 2018 and 2017 : Loans Acquired At December 31, (In thousands) 2018 2017 Consumer: Other consumer $ 15,658 $ 51,467 Real estate: Construction 429,605 637,032 Single family residential 566,188 793,228 Other commercial 1,848,679 2,387,777 Total real estate 2,844,472 3,818,037 Commercial: Commercial 430,914 995,587 Agricultural 1,739 66,576 Total commercial 432,653 1,062,163 Other — 142,409 Total loans acquired (1) $ 3,292,783 $ 5,074,076 _________________________ (1) Loans acquired are reported net of a $95,000 and $418,000 allowance as of December 31, 2018 and 2017 , respectively. Nonaccrual loans acquired, excluding purchased credit impaired loans accounted for under ASC Topic 310-30, segregated by class of loans, are as follows (see Note 5, Loans and Allowance for Loan Losses, for discussion of nonaccrual loans): (In thousands) December 31, 2018 December 31, 2017 Consumer: Other consumer $ 140 $ 334 Real estate: Construction 114 1,767 Single family residential 6,603 12,151 Other commercial 1,167 7,401 Total real estate 7,884 21,319 Commercial: Commercial 13,578 1,748 Agricultural 38 84 Total commercial 13,616 1,832 Total $ 21,640 $ 23,485 An age analysis of past due loans acquired segregated by class of loans, is as follows (see Note 5, Loans and Allowance for Loan Losses, for discussion of past due loans): (In thousands) Gross 30-89 Days Past Due 90 Days or More Past Due Total Past Due Current Total Loans 90 Days Past Due & Accruing December 31, 2018 Consumer: Other consumer $ 337 $ 49 $ 386 $ 15,272 $ 15,658 $ 2 Real estate: Construction 8,283 27 8,310 421,295 429,605 — Single family residential 4,706 3,049 7,755 558,433 566,188 — Other commercial 168 577 745 1,847,934 1,848,679 — Total real estate 13,157 3,653 16,810 2,827,662 2,844,472 — Commercial: Commercial 1,302 9,542 10,844 420,070 430,914 — Agricultural 31 5 36 1,703 1,739 — Total commercial 1,333 9,547 10,880 421,773 432,653 — Total $ 14,827 $ 13,249 $ 28,076 $ 3,264,707 $ 3,292,783 $ 2 December 31, 2017 Consumer: Other consumer $ 889 $ 260 $ 1,149 $ 50,318 $ 51,467 $ 108 Real estate: Construction 2,577 1,448 4,025 633,007 637,032 279 Single family residential 12,936 3,302 16,238 776,990 793,228 126 Other commercial 17,176 5,647 22,823 2,364,954 2,387,777 2,565 Total real estate 32,689 10,397 43,086 3,774,951 3,818,037 2,970 Commercial: Commercial 2,344 1,039 3,383 992,204 995,587 67 Agricultural 51 — 51 66,525 66,576 — Total commercial 2,395 1,039 3,434 1,058,729 1,062,163 67 Other 15 — 15 142,394 142,409 — Total $ 35,988 $ 11,696 $ 47,684 $ 5,026,392 $ 5,074,076 $ 3,145 The following table presents a summary of loans acquired by credit risk rating, segregated by class of loans (see Note 5, Loans and Allowance for Loan Losses, for discussion of loan risk rating). Loans accounted for under ASC Topic 310-30 are all included in Risk Rate 1-4 in this table. (In thousands) Risk Rate 1-4 Risk Rate 5 Risk Rate 6 Risk Rate 7 Risk Rate 8 Total December 31, 2018 Consumer: Other consumer $ 15,380 $ — $ 278 $ — $ — $ 15,658 Real estate: Construction 393,122 27,621 8,862 — — 429,605 Single family residential 553,460 2,081 10,299 348 — 566,188 Other commercial 1,822,179 9,137 17,363 — — 1,848,679 Total real estate 2,768,761 38,839 36,524 348 — 2,844,472 Commercial: Commercial 401,300 12,416 17,198 — — 430,914 Agricultural 1,642 — 97 — — 1,739 Total commercial 402,942 12,416 17,295 — — 432,653 Total $ 3,187,083 $ 51,255 $ 54,097 $ 348 $ — $ 3,292,783 December 31, 2017 Consumer: Other consumer $ 50,625 $ 21 $ 821 $ — $ — $ 51,467 Real estate: Construction 604,796 30,524 1,712 — — 637,032 Single family residential 770,954 2,618 19,656 — — 793,228 Other commercial 2,337,097 15,064 35,616 — — 2,387,777 Total real estate 3,712,847 48,206 56,984 — — 3,818,037 Commercial: Commercial 946,322 13,901 35,364 — — 995,587 Agricultural 66,367 — 209 — — 66,576 Total commercial 1,012,689 13,901 35,573 — — 1,062,163 Other 142,409 — — — — 142,409 Total $ 4,918,570 $ 62,128 $ 93,378 $ — $ — $ 5,074,076 Loans acquired were individually evaluated and recorded at estimated fair value, including estimated credit losses, at the time of acquisition. These loans are systematically reviewed by the Company to determine the risk of losses that may exceed those identified at the time of the acquisition. Techniques used in determining risk of loss are similar to the Company’s legacy loan portfolio, with most focus being placed on those loans which include the larger loan relationships and those loans which exhibit higher risk characteristics. The following is a summary of the loans acquired in the OKSB acquisition on October 19, 2017, as of the date of acquisition. (In thousands) Not Impaired Impaired Contractually required principal and interest at acquisition $ 2,021,388 $ 18,136 Non-accretable difference (expected losses and foregone interest) — (6,731 ) Cash flows expected to be collected at acquisition 2,021,388 11,405 Accretable yield (36,340 ) — Basis in acquired loans at acquisition $ 1,985,048 $ 11,405 The following is a summary of the loans acquired in the First Texas acquisition on October 19, 2017, as of the date of acquisition. (In thousands) Not Impaired Impaired Contractually required principal and interest at acquisition $ 2,246,212 $ — Non-accretable difference (expected losses and foregone interest) — — Cash flows expected to be collected at acquisition 2,246,212 — Accretable yield (37,834 ) — Basis in acquired loans at acquisition $ 2,208,378 $ — The following is a summary of the loans acquired in the Hardeman acquisition on May 15, 2017, as of the date of acquisition. (In thousands) Not Impaired Impaired Contractually required principal and interest at acquisition $ 254,189 $ 3,452 Non-accretable difference (expected losses and foregone interest) — (990 ) Cash flows expected to be collected at acquisition 254,189 2,462 Accretable yield (5,002 ) — Basis in acquired loans at acquisition $ 249,187 $ 2,462 The following is a summary of the loans acquired in the Citizens acquisition on September 9, 2016, as of the date of acquisition. (In thousands) Not Impaired Impaired Contractually required principal and interest at acquisition $ 348,756 $ 1,605 Non-accretable difference (expected losses and foregone interest) — (848 ) Cash flows expected to be collected at acquisition 348,756 757 Accretable yield (8,663 ) — Basis in acquired loans at acquisition $ 340,093 $ 757 In addition to the accretable yield on acquired loans not considered to be impaired, the amount of the estimated cash flows expected to be received from the purchased credit impaired loans in excess of the fair values recorded for the purchased credit impaired loans is also referred to as the accretable yield. The accretable yield is recognized as interest income over the estimated lives of the loans. Each quarter, the Company estimates the cash flows expected to be collected from the acquired purchased credit impaired loans, and adjustments may or may not be required. This has resulted in an increase in interest income that is spread on a level-yield basis over the remaining expected lives of the loans. These adjustments will be recognized over the remaining lives of the purchased credit impaired loans. The accretable yield adjustments recorded in future periods will change as the Company continues to evaluate expected cash flows from the purchased credit impaired loans. Changes in the carrying amount of the accretable yield for all purchased impaired loans were as follows for the years ended December 31, 2018 , 2017 and 2016 . (In thousands) Accretable Yield Carrying Amount of Loans Balance, January 1, 2016 $ 954 $ 23,469 Additions 19 757 Accretable yield adjustments 5,122 — Accretion (4,440 ) 4,440 Payments and other reductions, net — (10,864 ) Balance, December 31, 2016 1,655 17,802 Additions — 13,793 Accretable yield adjustments 4,893 — Accretion (5,928 ) 5,928 Payments and other reductions, net — (20,407 ) Balance, December 31, 2017 620 17,116 Additions — — Accretable yield adjustments 2,045 — Accretion (1,205 ) 1,205 Payments and other reductions, net — (14,271 ) Balance, December 31, 2018 $ 1,460 $ 4,050 Purchased impaired loans are evaluated on an individual borrower basis. Because some loans evaluated by the Company were determined to have experienced impairment in the estimated credit quality or cash flows, the Company recorded a provision and established an allowance for loan losses for loans acquired resulting in a total allowance on loans acquired of $95,000 at December 31, 2018 , $418,000 at December 31, 2017 and $954,000 at December 31, 2016 .

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill is tested annually, or more often than annually, if circumstances warrant, for impairment. If the implied fair value of goodwill is lower than its carrying amount, goodwill impairment is indicated, and goodwill is written down to its implied fair value. Subsequent increases in goodwill value are not recognized in the financial statements. Goodwill totaled $845.7 million at December 31, 2018 and $842.7 million at December 31, 2017 . The Company recorded $229.1 million , $240.8 million and $29.4 million of goodwill as a result of its acquisitions of OKSB, First Texas and Hardeman, respectively, partially offset by $4.1 million due to the sale of the Company’s property and casualty insurance lines of business during the third quarter 2017. The Company recorded $21.5 million of goodwill during 2016 as a result of its Citizens acquisition. Goodwill impairment was neither indicated nor recorded in 2018 , 2017 or 2016 . The goodwill recorded in the Citizens acquisition will be deductible for tax purposes. Core deposit premiums are amortized over periods ranging from 10 to 15 years and are periodically evaluated, at least annually, as to the recoverability of their carrying value. Core deposit premiums of $42.1 million , $7.3 million , and $7.8 million were recorded during 2017 as part of the OKSB, First Texas and Hardeman acquisitions, respectively. Core deposit premiums of $5.1 million were recorded in 2016 as part of the Citizens acquisition. Intangible assets are being amortized over various periods ranging from 10 to 15 years. The Company recorded $830,000 and $3.8 million of intangible assets during 2017 related to the insurance operations in the Hardeman acquisition and the OKSB acquisition, respectively. The Company recorded $591,000 of intangible assets during 2016 related to the trust operations acquired in the Citizens acquisition. Intangible assets decreased by $1.3 million due to the sale of insurance lines of business during the third quarter of 2017 and decreased $3.8 million due to the sale of the OKSB intangible asset in the first quarter of 2018. The Company’s goodwill and other intangibles (carrying basis and accumulated amortization) at December 31, 2018 and 2017 were as follows: (In thousands) 2018 2017 Goodwill $ 845,687 $ 842,651 Core deposit premiums: Gross carrying amount 105,984 105,984 Accumulated amortization (26,177 ) (16,659 ) Core deposit premiums, net 79,807 89,325 Books of business intangible: Gross carrying amount 15,234 15,414 Accumulated amortization (3,707 ) (2,827 ) Books of business intangible, net 11,527 12,587 Other intangibles: Gross carrying amount 2,068 6,037 Accumulated amortization (2,068 ) (1,878 ) Other intangibles, net — 4,159 Other intangible assets, net 91,334 106,071 Total goodwill and other intangible assets $ 937,021 $ 948,722 Core deposit premium amortization expense recorded for the years ended December 31, 2018 , 2017 and 2016 was $9.5 million , $6.0 million and $4.4 million , respectively. Amortization expense recorded for purchased credit card relationships for the year ended December 31, 2018 was $310,000 and $414,000 for the years ended December 31, 2017 and 2016 . Book of business amortization expense recorded for the years ended December 31, 2018 , 2017 and 2016 was $1.1 million . The Company’s estimated remaining amortization expense on intangibles as of December 31, 2018 is as follows: Year (In thousands) 2019 $ 10,565 2020 10,552 2021 10,490 2022 10,438 2023 10,156 Thereafter 39,133 Total $ 91,334

Time Deposits

Time Deposits	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Time Deposits	TIME DEPOSITS Time deposits included approximately $1.443 billion and $736.0 million of certificates of deposit of $100,000 or more, at December 31, 2018 and 2017 , respectively. Of this total approximately $753.2 million and $396.8 million of certificates of deposit were over $250,000 at December 31, 2018 and 2017 , respectively. Brokered time deposits were $1.386 billion and $442.0 million at December 31, 2018 and 2017 , respectively. Maturities of all time deposits are as follows: 2019 – $2.384 billion ; 2020 – $407.92 million ; 2021 – $83.74 million ; 2022 – $13.47 million ; 2023 – $6.94 million ; thereafter – $85,000 . Deposits are the Company’s primary funding source for loans and investment securities. The mix and repricing alternatives can significantly affect the cost of this source of funds and, therefore, impact the interest margin.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES The provision for income taxes for the years ended December 31 is comprised of the following components: (In thousands) 2018 2017 2016 Income taxes currently payable $ 41,946 $ 38,732 $ 36,792 Deferred income taxes 8,412 23,251 9,832 Provision for income taxes $ 50,358 $ 61,983 $ 46,624 The tax effects of temporary differences between the tax basis of assets and liabilities and their financial reporting amounts that give rise to deferred income tax assets and liabilities, and their approximate tax effects, are as follows as of December 31, 2018 and 2017 : (In thousands) 2018 2017 Deferred tax assets: Loans acquired $ 12,536 $ 19,885 Allowance for loan losses 13,947 10,773 Valuation of foreclosed assets 1,474 2,852 Tax NOLs from acquisition 7,242 7,821 Deferred compensation payable 2,707 2,433 Accrued equity and other compensation 8,182 5,302 Acquired securities 397 578 Unrealized loss on available-for-sale securities 9,196 6,107 Other 7,042 8,813 Gross deferred tax assets 62,723 64,564 Deferred tax liabilities: Goodwill and other intangible amortization (30,471 ) (32,572 ) Accumulated depreciation (13,361 ) (8,945 ) Other (5,360 ) (4,413 ) Gross deferred tax liabilities (49,192 ) (45,930 ) Net deferred tax asset, included in other assets $ 13,531 $ 18,634 A reconciliation of income tax expense at the statutory rate to the Company’s actual income tax expense is shown below for the years ended December 31: (In thousands) 2018 2017 2016 Computed at the statutory rate (1) $ 55,875 $ 54,223 $ 50,203 Increase (decrease) in taxes resulting from: State income taxes, net of federal tax benefit 5,015 1,582 2,121 Discrete items related to ASU 2016-09 (2,439 ) (1,480 ) — Tax exempt interest income (3,168 ) (4,209 ) (4,207 ) Tax exempt earnings on BOLI (869 ) (926 ) (905 ) Federal tax credits (3,003 ) (1,586 ) (1,161 ) Impact of DTA remeasurement — 11,471 — Other differences, net (1,053 ) 2,908 573 Actual tax provision $ 50,358 $ 61,983 $ 46,624 _________________________ (1) The statutory rate was 21% for 2018 compared to 35% for 2017 and 2016. The Company follows ASC Topic 740, Income Taxes , which prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. Benefits from tax positions should be recognized in the financial statements only when it is more likely than not that the tax position will be sustained upon examination by the appropriate taxing authority that would have full knowledge of all relevant information. A tax position that meets the more-likely-than-not recognition threshold is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. Tax positions that previously failed to meet the more-likely-than-not recognition threshold should be recognized in the first subsequent financial reporting period in which that threshold is met. Previously recognized tax positions that no longer meet the more-likely-than-not recognition threshold should be derecognized in the first subsequent financial reporting period in which that threshold is no longer met. ASC Topic 740 also provides guidance on the accounting for and disclosure of unrecognized tax benefits, interest and penalties. The Company has no history of expiring net operating loss carryforwards and is projecting significant pre-tax and financial taxable income in 2018 and in future years. The Company expects to fully realize its deferred tax assets in the future. Income tax expense was lower during 2018 largely due to discrete tax benefits related to tax accounting for a cost segregation study, excess tax benefits related to restricted stock and a state tax deferred tax asset (“DTA”) adjustment. The purpose of the cost segregation study was to analyze the costs included in various projects and recognize the benefit of recording tax deprecation in 2017 when the federal rate was higher. The purpose of the state DTA adjustment was due to an analysis of projected state apportionment after the 2017 acquisitions of First South Bank, Bank SNB and Southwest Bank were merged into Simmons Bank in 2018. On December 22, 2017, the President signed tax reform legislation (the “2017 Act”) which included a broad range of tax reform provisions affecting businesses, including corporate tax rates, business deductions, and international tax provisions. The 2017 Act reduced the corporate tax rate from 35% to 21% for tax years beginning after December 31, 2017. Under US GAAP, deferred tax assets and liabilities are required to be measured at the enacted tax rate expected to apply when temporary differences are to be realized or settled and the effect of a change in tax law is recorded discretely as a component of the income tax provision related to continuing operations in the period of enactment. As a result, the Company was required to remeasure its deferred taxes as of December 22, 2017 based upon the new 21% tax rate and the change was recorded in the 2017 income tax provision. The 2017 Act resulted in a one-time non-cash adjustment to income of $11.5 million in 2017. On December 22, 2017, the Securities and Exchange Commission (“SEC”) issued Staff Accounting Bulletin No. 118 (“SAB 118”), which provided guidance on accounting for the tax effects of the 2017 Act. SAB 118 provided a measurement period that should not exceed one year from the 2017 Act enactment date for companies to complete the accounting under ASC 740, Income Taxes . The Company’s financial results for the year ended December 31, 2017 reflected the income tax effects for the 2017 Act including several provisional amounts based on reasonable estimates. Any items that were estimated in 2017 were finalized in 2018 with no material impact to the company’s federal income tax expense. In February 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) No. 2018-2, Income Statement-Reporting Comprehensive Income (Topic 220) (“ASU 2018-2”), that allows a reclassification from accumulated other comprehensive income (“AOCI”) to retained earnings for stranded tax effects resulting from the 2017 Act. Current US GAAP requires the remeasurement of deferred tax assets and liabilities as a result of a change in tax laws or rates to be presented in net income from continuing operations. Consequently, the original deferred tax amount recorded through AOCI at the old rate will remain in AOCI despite the fact that its related deferred tax asset/liability will be reduced through continuing operations to reflect the new rate, resulting in “stranded” tax effects in AOCI. ASU 2018-2 requires a reclassification from AOCI to retained earnings for those stranded tax effects resulting from the newly enacted federal corporate income tax rate. As permitted, the Company elected to early adopt the provisions of ASU 2018-2 during the fourth quarter 2017, which resulted in a reclassification from AOCI to retained earnings in the amount of $3.0 million . The amount of unrecognized tax benefits may increase or decrease in the future for various reasons including adding amounts for current tax year positions, expiration of open income tax returns due to the statutes of limitation, changes in management’s judgment about the level of uncertainty, status of examinations, litigation and legislative activity and the addition or elimination of uncertain tax positions. Section 382 of the Internal Revenue Code imposes an annual limit on the ability of a corporation that undergoes an “ownership change” to use its U.S. net operating losses to reduce its tax liability. The Company closed a stock acquisition in 2015 that invoked the Section 382 annual limitation. Approximately $33.8 million of federal net operating losses subject to the IRC Sec 382 annual limitation are expected to be utilized by the company. The net operating loss carryforwards expire between 2028 and 2035. The Company files income tax returns in the U.S. federal jurisdiction. The Company’s U.S. federal income tax returns are open and subject to examinations from the 2015 tax year and forward. The Company’s various state income tax returns are generally open from the 2015 and later tax return years based on individual state statute of limitations.

Securities Sold Under Agreement

Securities Sold Under Agreements to Repurchase	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Securities Sold Under Agreements to Repurchase	SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE The Company utilizes securities sold under agreements to repurchase to facilitate the needs of its customers and to facilitate secured short-term funding needs. Securities sold under agreements to repurchase are stated at the amount of cash received in connection with the transaction. The Company monitors collateral levels on a continuous basis. The Company may be required to provide additional collateral based on the fair value of the underlying securities. Securities pledged as collateral under repurchase agreements are maintained with the Company’s safekeeping agents. The gross amount of recognized liabilities for repurchase agreements was $95.5 million and $122.0 million at December 31, 2018 and 2017 , respectively. The remaining contractual maturity of the securities sold under agreements to repurchase in the consolidated balance sheets as of December 31, 2018 and 2017 is presented in the following tables. Remaining Contractual Maturity of the Agreements (In thousands) Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total December 31, 2018 Repurchase agreements: U.S. Government agencies $ 95,542 $ — $ — $ — $ 95,542 December 31, 2017 Repurchase agreements: U.S. Government agencies $ 122,019 $ — $ — $ — $ 122,019

Other Borrowings and Subordinat

Other Borrowings and Subordinated Debentures	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Other Borrowings and Subordinated Debentures	OTHER BORROWINGS AND SUBORDINATED NOTES AND DEBENTURES Debt at December 31, 2018 and 2017 consisted of the following components. (In thousands) 2018 2017 Other Borrowings FHLB advances, net of discount, due 2019 to 2033, 1.38% to 7.37% secured by residential real estate loans $ 1,345,450 $ 1,261,642 Revolving credit agreement, due 10/4/2019, floating rate of 1.50% above the one month LIBOR rate, unsecured — 75,000 Notes payable, due 10/15/2020, 3.85%, fixed rate, unsecured — 43,382 Total other borrowings 1,345,450 1,380,024 Subordinated Notes and Debentures Subordinated notes payable, due 4/1/2028, fixed-to-floating rate (fixed rate of 5.00% through 3/31/2023, floating rate of 2.15% above the three month LIBOR rate, reset quarterly) 330,000 — Trust preferred securities, due 12/30/2033, floating rate of 2.80% above the three month LIBOR rate, reset quarterly, callable without penalty — 20,620 Trust preferred securities, net of discount, due 6/30/2035, floating rate of 1.75% above the three month LIBOR rate, reset quarterly, callable without penalty — 9,327 Trust preferred securities, net of discount, due 9/15/2037, floating rate of 1.37% above the three month LIBOR rate, reset quarterly 10,310 10,284 Trust preferred securities, net of discount, due 12/5/2033, floating rate of 2.88% above the three month LIBOR rate, reset quarterly, callable without penalty — 5,156 Trust preferred securities, net of discount, due 10/18/2034, floating rate of 2.00% above the three month LIBOR rate, reset quarterly, callable without penalty — 5,148 Trust preferred securities, net of discount, due 6/6/2037, floating rate of 1.57% above the three month LIBOR rate, reset quarterly, callable without penalty 10,310 10,288 Trust preferred securities, due 12/15/2035, floating rate of 1.45% above the three month LIBOR rate, reset quarterly, callable without penalty 6,702 6,702 Trust preferred securities, due 6/26/2033, floating rate of 3.10% above the three month LIBOR rate, reset quarterly, callable without penalty — 20,619 Trust preferred securities, due 10/7/2033, floating rate of 2.85% above the three month LIBOR rate, reset quarterly, callable without penalty — 25,774 Trust preferred securities, due 9/15/2037, floating rate of 2.00% above the three month LIBOR rate, reset quarterly, callable without penalty — 8,248 Other subordinated debentures, net of discount, due 9/30/2023, floating rate equal to daily average of prime rate, reset quarterly — 18,399 Unamortized debt issuance costs (3,372 ) — Total subordinated notes and debentures 353,950 140,565 Total other borrowings and subordinated debt $ 1,699,400 $ 1,520,589 In March 2018, the Company issued $330.0 million in aggregate principal amount, of 5.00% Fixed-to-Floating Rate Subordinated Notes (“the Notes”) at a public offering price equal to 100% of the aggregate principal amount of the Notes. The Company incurred $3.6 million in debt issuance costs related to the offering during March. The Notes will mature on April 1, 2028 and will bear interest at an initial fixed rate of 5.00% per annum, payable semi-annually in arrears. From and including April 1, 2023 to, but excluding, the maturity date or the date of earlier redemption, the interest rate will reset quarterly to an annual interest rate equal to the then-current three month LIBOR rate plus 215 basis points, payable quarterly in arrears. The Notes will be subordinated in right of payment to the payment of the Company’s other existing and future senior indebtedness, including all of its general creditors. The Notes are obligations of Simmons First National Corporation only and are not obligations of, and are not guaranteed by, any of its subsidiaries. During 2018 , the Company used a portion of the net proceeds from the sale of the Notes to repay certain outstanding indebtedness, including the amounts borrowed under the Revolving Credit Agreement (the “Credit Agreement”), certain trust preferred securities, both discussed below, and unsecured debt from correspondent banks. The subordinated notes qualify for Tier 2 capital treatment. In October 2017, the Company entered into the Credit Agreement with U.S. Bank National Association and executed an unsecured Revolving Credit Note pursuant to which the Company may borrow, prepay and re-borrow up to $75.0 million , the proceeds of which were primarily used to pay off amounts outstanding under a term note assumed with the First Texas acquisition. The Credit Agreement contained customary representations, warranties, and covenants of the Company, including, among other things, covenants that impose various financial ratio requirements. In October 2018, the Company and U.S. Bank National Association entered into a First Amendment to the Credit Agreement, which extended the expiration date from October 5, 2018 to October 4, 2019, reduced the $75.0 million to $50.0 million , and increased the commitment fee on the unused portion from an annual rate of 0.25% to 0.30% . In October 2019, all amounts borrowed, together with applicable interest, fees, and other amounts owed by the Company are due and payable. The balance due under the Credit Agreement at December 31, 2018 was zero . In connection with the OKSB and First Texas acquisitions in October 2017, the Company assumed subordinated debt in an aggregate principal amount, net of discounts, of $77.3 million . The Company assumed subordinated debt of $6.7 million in connection with the Hardeman acquisition in May 2017. The other subordinated debentures acquired from First Texas for approximately $19.1 million were called September 30, 2018. The outstanding principal and interest was paid to the holders of the subordinated debt during the fourth quarter. At December 31, 2018 , the Company had $1.3 billion of Federal Home Loan Bank (“FHLB”) advances outstanding with original or expected maturities of one year or less, of which $675.0 million are FHLB Owns the Option (“FOTO”) advances. FOTO advances are a low cost, fixed-rate source of funding in return for granting to FHLB the flexibility to choose a termination date earlier than the maturity date. Typically, FOTO exercise dates follow a specified lockout period at the beginning of the term when FHLB cannot terminate the FOTO advance. If FHLB exercises its option to terminate the FOTO advance at one of the specified option exercise dates, there is no termination or prepayment fee, and replacement funding will be available at then-prevailing market rates, subject to FHLB’s credit and collateral requirements. The Company’s FOTO advances outstanding at the end of the year have ten to fifteen year maturity dates with lockout periods that vary but do not exceed one year. These FOTO advances are considered and monitored by the Company as short-term advances due to the likelihood of FHLB exercising the options within a year of the settlement dates based upon the rising rate environment and the short lockout periods. The Company had total FHLB advances of $1.3 billion at December 31, 2018 , with approximately $1.8 billion of additional advances available from the FHLB. The FHLB advances are secured by mortgage loans and investment securities totaling approximately $4.6 billion at December 31, 2018 . The trust preferred securities are tax-advantaged issues that qualified for Tier 1 capital treatment until December 31, 2017, when the Company reached $15 billion in assets. They still qualify for inclusion as Tier 2 capital at December 31, 2018 . Distributions on these securities are included in interest expense on long-term debt. Each of the trusts is a statutory business trust organized for the sole purpose of issuing trust securities and investing the proceeds thereof in junior subordinated debentures of the Company, the sole asset of each trust. The preferred securities of each trust represent preferred beneficial interests in the assets of the respective trusts and are subject to mandatory redemption upon payment of the junior subordinated debentures held by the trust. The common securities of each trust are wholly-owned by the Company. Each trust’s ability to pay amounts due on the trust preferred securities is solely dependent upon the Company making payments on the related junior subordinated debentures. The Company’s obligations under the junior subordinated securities and other relevant trust agreements, in aggregate, constitute a full and unconditional guarantee by the Company of each respective trust’s obligations under the trust securities issued by each respective trust. The Company’s long-term debt includes subordinated debt, notes payable and long-term FHLB advances with an original maturity of greater than one year. Aggregate annual maturities of long-term debt at December 31, 2018 , are as follows: Year (In thousands) 2019 $ 2,135 2020 2,109 2021 1,800 2022 949 2023 923 Thereafter 361,484 Total $ 369,400

Capital Stock

Capital Stock	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Capital Stock	CAPITAL STOCK On February 27, 2009, at a special meeting, the Company’s shareholders approved an amendment to the Articles of Incorporation to establish 40,040,000 authorized shares of preferred stock, $0.01 par value. The aggregate liquidation preference of all shares of preferred stock cannot exceed $80,000,000 . On January 18, 2018, the board of directors of the Company approved a two-for-one stock split of the Corporation’s outstanding Class A common stock (“Common Stock”) in the form of a 100% stock dividend for shareholders of record as of the close of business on January 30, 2018 (“Record Date”). The new shares were distributed by the Company’s transfer agent, Computershare, and the Company’s common stock began trading on a split-adjusted basis on the NASDAQ Global Select Market on February 9, 2018. All previously reported share and per share data included in filings subsequent to the Payment Date are restated to reflect the retroactive effect of this two -for-one stock split. On March 19, 2018, the Company filed a shelf registration with the SEC. The shelf registration statement provides increased flexibility and more efficient access to raise capital from time to time through the sale of common stock, preferred stock, debt securities, depository shares, warrants, purchase contracts, purchase units, subscription rights, units or a combination thereof, subject to market conditions. Specific terms and prices are determined at the time of any offering under a separate prospectus supplement that the Company is required to file with the SEC at the time of the specific offering. On April 19, 2018, shareholders of the Company approved an increase in the number of authorized shares from 120,000,000 to 175,000,000 . On February 27, 2015, as part of the acquisition of Community First, the Company issued 30,852 shares of Senior Non-Cumulative Perpetual Preferred Stock, Series A (“Simmons Series A Preferred Stock”) in exchange for the outstanding shares of Community First Senior Non-Cumulative Perpetual Preferred Stock, Series C (“Community First Series C Preferred Stock”). The preferred stock was held by the United States Department of the Treasury (“Treasury”) as the Community First Series C Preferred Stock was issued when Community First entered into a Small Business Lending Fund Securities Purchase Agreement with the Treasury. The Simmons Series A Preferred Stock qualified as Tier 1 capital and paid quarterly dividends. The rate remained fixed at 1% through February 18, 2016, at which time it would convert to a fixed rate of 9% . On January 29, 2016, the Company redeemed all of the preferred stock, including accrued and unpaid dividends. On July 23, 2012, the Company approved a stock repurchase program which authorized the repurchase of up to 1,700,000 shares (split adjusted) of Class A common stock, or approximately 2% of the shares outstanding. Under the current plan, the Company can repurchase an additional 308,272 shares. The shares are to be purchased from time to time at prevailing market prices, through open market or unsolicited negotiated transactions, depending upon market conditions. Under the repurchase program, there is no time limit for the stock repurchases, nor is there a minimum number of shares that the Company intends to repurchase. The Company may discontinue purchases at any time that management determines additional purchases are not warranted. The Company intends to use the repurchased shares to satisfy stock option exercises, payment of future stock awards and dividends and general corporate purposes.

Transactions With Related Parti

Transactions With Related Parties	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Transactions With Related Parties	TRANSACTIONS WITH RELATED PARTIES At December 31, 2018 and 2017 , Simmons Bank had extensions of credit to executive officers and directors and to companies in which Simmons Bank’s executive officers or directors were principal owners in the amount of $66.4 million in 2018 and $58.9 million in 2017 . (In thousands) 2018 2017 Balance, beginning of year $ 58,867 $ 65,834 New extensions of credit 7,661 9,092 Repayments (137 ) (16,059 ) Balance, end of year $ 66,391 $ 58,867 In management’s opinion, such loans and other extensions of credit, deposits and vendor contracts (which were not material) were made in the ordinary course of business and were made on substantially the same terms (including interest rates and collateral) as those prevailing at the time for comparable transactions with other persons or through a competitive bid process. Further, in management’s opinion, these extensions of credit did not involve more than the normal risk of collectability or present other unfavorable features.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS Retirement Plans The Company has a 401(k) retirement plan that covers substantially all employees. The Company has also historically had a discretionary profit sharing and employee stock ownership plan (“ESOP”) covering substantially all employees. Effective December 31, 2016, the ESOP was merged into the Company’s 401(k) retirement plan. This merger allows participants to fully diversify their ESOP account balance and have reporting access to all retirement account balances in one place. Contribution expense to the plans totaled $10,769,000 , $6,343,000 and $5,488,000 in 2018 , 2017 and 2016 , respectively. The Company also provides deferred compensation agreements with certain active and retired officers. The agreements provide monthly payments of retirement compensation for either stated periods or for the life of the participant. The charges to income for the plans were $2,309,000 for 2018 , $1,596,000 for 2017 and $1,056,000 for 2016 . Such charges reflect the straight-line accrual over the employment period of the present value of benefits due each participant, as of their full eligibility date, using an appropriate discount factor. Employee Stock Purchase Plan The Company established an Employee Stock Purchase Plan in 2015 which generally allows participants to make contributions of up to $25,000 per year, for the purpose of acquiring the Company’s stock. At the end of each plan year, full shares of the Company’s stock are purchased for each employee based on that employee’s contributions. The Company has issued both general and special stock offerings under the plan. Substantially all employees are eligible for the general stock offering, under which full shares of the Company’s stock are purchased for an amount equal to 95% of their fair market value at the end of the plan year, or, if lower, 95% of their fair market value at the beginning of the plan year. The special stock offering is available to substantially all non-highly compensated employees with at least six months of service, and these employees may allocate up to $10,000 to this offering. Under the special stock offering, full shares of the Company’s stock are purchased for an amount equal to 85% of their fair market value at the end of the plan year, or, if lower, 85% of their fair market value at the beginning of the plan year. Stock-Based Compensation Plans The Company’s Board of Directors has adopted various stock-based compensation plans. The plans provide for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock awards, restricted stock units and performance stock units. Pursuant to the plans, shares are reserved for future issuance by the Company upon exercise of stock options or awarding of bonus shares granted to directors, officers and other key employees. Stock-based compensation expense for all stock-based compensation awards granted after January 1, 2006, is based on the grant date fair value. For all awards except stock option awards, the grant date fair value is the market value per share as of the grant date. For stock option awards, the fair value is estimated at the date of grant using the Black-Scholes option-pricing model. This model requires the input of highly subjective assumptions, changes to which can materially affect the fair value estimate. Additionally, there may be other factors that would otherwise have a significant effect on the value of employee stock options granted but are not considered by the model. Accordingly, while management believes that the Black-Scholes option-pricing model provides a reasonable estimate of fair value, the model does not necessarily provide the best single measure of fair value for the Company’s employee stock options. The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model that uses various assumptions. Expected volatility is based on historical volatility of the Company’s stock and other factors. The Company uses historical data to estimate option exercise and employee termination within the valuation model. The expected term of options granted is derived from the output of the option valuation model and represents the period of time that options granted are expected to be outstanding. The risk-free rate for periods within the contractual life of the option is based on the U.S. Treasury yield curve in effect at the time of grant. Forfeitures are estimated at the time of grant, and are based partially on historical experience. Share and per share information regarding Stock-Based Compensation Plans has been adjusted to reflect the effects of the Company’s two -for-one stock split which became effective on February 8, 2018. The table below summarizes the transactions under the Company’s active stock compensation plans at December 31, 2018 , 2017 and 2016 , and changes during the years then ended: Stock Options Outstanding Stock Awards Outstanding Stock Units Outstanding Number of Shares (000) Weighted Average Exercise Price Number of Shares (000) Weighted Average Exercise Price Number of Shares (000) Weighted Average Exercise Price Balance, December 31, 2015 970 $ 20.31 342 $ 17.83 158 $ 21.33 Granted 116 23.51 272 23.46 286 23.48 Stock options exercised (127 ) 15.14 — — — — Stock awards/units vested — — (318 ) 20.96 (25 ) 22.77 Forfeited/expired (13 ) 17.53 (18 ) 21.85 (13 ) 23.04 Balance, December 31, 2016 946 21.43 278 20.48 406 22.70 Granted — — — — 906 28.86 Stock options exercised (122 ) 17.66 — — — — Stock awards/units vested — — (91 ) 19.40 (449 ) 27.13 Forfeited/expired (12 ) 22.67 (25 ) 21.91 (35 ) 25.76 Balance, December 31, 2017 812 21.98 162 20.85 828 26.13 Granted — — — — 429 29.16 Stock options exercised (112 ) 19.22 — — — — Stock awards/units vested — — (80 ) 20.41 (311 ) 25.56 Forfeited/expired (5 ) 21.73 (10 ) 20.12 (129 ) 27.95 Balance, December 31, 2018 695 $ 22.42 72 $ 21.45 817 $ 27.65 Exercisable, December 31, 2018 662 $ 22.37 The following table summarizes information about stock options under the plans outstanding at December 31, 2018 : Options Outstanding Options Exercisable Range of Exercise Prices Number of Shares (000) Weighted Average Remaining Contractual Life (Years) Weighted Average Exercise Price Number of Shares (000) Weighted Average Exercise Price $ 9.46 — $ 9.46 1 3.04 $9.46 1 $9.46 10.65 — 10.65 4 4.07 10.65 4 10.65 10.76 — 10.76 2 1.05 10.76 2 10.76 20.29 — 20.29 71 6.00 20.29 71 20.29 20.36 — 20.36 3 5.88 20.36 2 20.36 22.20 — 22.20 74 6.23 22.20 74 22.20 22.75 — 22.75 436 6.61 22.75 436 22.75 23.51 — 23.51 97 7.05 23.51 65 23.51 24.07 — 24.07 7 6.71 24.07 7 24.07 $ 9.46 — $ 24.07 695 6.53 $22.42 662 $22.37 The table below summarizes the Company’s restricted performance stock unit activity for the years ended December 31, 2018 , 2017 and 2016 : (In thousands) Performance Stock Units Non-vested, December 31, 2015 118 Granted 70 Vested (earned) — Forfeited (7 ) Non-vested, December 31, 2016 181 Granted 57 Vested (earned) (57 ) Forfeited (4 ) Non-vested, December 31, 2017 177 Granted 72 Vested (earned) (55 ) Forfeited (17 ) Non-vested, December 31, 2018 177 Stock-based compensation expense was $11,227,000 in 2018 , $11,763,000 in 2017 and $5,451,000 in 2016 . Stock-based compensation expense is recognized ratably over the requisite service period for all stock-based awards. There was no unrecognized stock-based compensation expense related to stock options at December 31, 2018 . Unrecognized stock-based compensation expense related to non-vested stock awards and stock units was $14,714,000 at December 31, 2018 . At such date, the weighted-average period over which this unrecognized expense is expected to be recognized was 1.7 years. The intrinsic value of stock options outstanding and stock options exercisable at December 31, 2018 was $1,187,000 and $1,165,000 . Aggregate intrinsic value represents the difference between the Company’s closing stock price on the last trading day of the period, which was $24.13 at December 31, 2018 , and the exercise price multiplied by the number of options outstanding. There were 111,728 stock options exercised in 2018 with an intrinsic value of $561,000 . There were 122,012 stock options exercised in 2017 with an intrinsic value of $1,329,000 . There were 127,424 stock options exercised in 2016 with an intrinsic value of $2,031,000 . The fair value of the Company’s employee stock options granted is estimated on the date of grant using the Black-Scholes option-pricing model. This model requires the input of highly subjective assumptions, changes to which can materially affect the fair value estimate. There were no stock options granted during the years ended December 31, 2018 and 2017. The weighted-average fair value of stock options granted during the year ended December 31, 2016 was $5.82 per share. The Company estimated expected market price volatility and expected term of the options based on historical data and other factors. The weighted-average assumptions used to determine the fair value of options granted for the years ended December 31, 2016 is detailed in the table below: 2016 Expected dividend yield 1.96 % Expected stock price volatility 27.34 % Risk-free interest rate 2.01 % Expected life of options (in years) 7

Additional Cash Flow Informatio

Additional Cash Flow Information	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Additional Cash Flow Information	ADDITIONAL CASH FLOW INFORMATION The following is a summary of the Company’s additional cash flow information during the years ended December 31: (In thousands) 2018 2017 2016 Interest paid $ 122,801 $ 39,384 $ 22,069 Income taxes paid 25,718 35,770 39,824 Transfers of loans to foreclosed assets held for sale 16,858 6,983 4,604 Transfers of premises to foreclosed assets and other real estate owned 3,690 5,422 — Transfers of premises held for sale to foreclosed assets and other real estate owned — 3,188 652

Other Operating Expenses

Other Operating Expenses	12 Months Ended
	Dec. 31, 2018
Other Income and Expenses [Abstract]
Other Operating Expenses	OTHER OPERATING EXPENSES Other operating expenses consist of the following: (In thousands) 2018 2017 2016 Professional services $ 16,685 $ 19,500 $ 14,630 Postage 5,785 4,686 4,599 Telephone 5,947 4,262 4,294 Credit card expense 14,338 12,188 11,328 Marketing 8,410 11,141 6,929 Operating supplies 2,346 1,980 1,824 Amortization of intangibles 11,009 7,668 5,945 Branch right sizing expense 1,341 434 3,600 Other expense 45,714 27,020 20,364 Total other operating expenses $ 111,575 $ 88,879 $ 73,513 The Company had aggregate annual equipment rental expense of approximately $2,922,000 in 2018 , $2,200,000 in 2017 and $2,300,000 in 2016 . The Company leases a portion of its ATMs, accounting for approximately $1,697,000 , $1,335,000 and $1,338,000 of the 2018 , 2017 and 2016 , respectively, of rental expense. The Company had aggregate annual occupancy rental expense of approximately $10,456,000 in 2018 , $5,580,000 in 2017 and $4,643,000 in 2016 .

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS ASC Topic 820, Fair Value Measurements defines fair value, establishes a framework for measuring fair value and expands disclosures about fair value measurements. ASC Topic 820 defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The guidance also establishes a fair value hierarchy that requires the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. Topic 820 describes three levels of inputs that may be used to measure fair value: • Level 1 Inputs – Quoted prices in active markets for identical assets or liabilities. • Level 2 Inputs – Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities in active markets; quoted prices for similar assets or liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. • Level 3 Inputs – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. In general, fair value is based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon internally developed models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments may include amounts to reflect counterparty credit quality and the Company’s creditworthiness, among other things, as well as unobservable parameters. Any such valuation adjustments are applied consistently over time. The Company’s valuation methodologies may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. While management believes the Company’s valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date. Furthermore, the reported fair value amounts have not been comprehensively revalued since the presentation dates, and therefore, estimates of fair value after the balance sheet date may differ significantly from the amounts presented herein. A more detailed 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. Following is a description of the inputs and valuation methodologies used for assets measured at fair value on a recurring basis and recognized in the accompanying consolidated balance sheets, as well as the general classification of such assets pursuant to the valuation hierarchy. Available-for-sale securities – Where quoted market prices are available in an active market, securities are classified within Level 1 of the valuation hierarchy. Level 1 securities would include highly liquid government bonds, mortgage products and exchange traded equities. Other securities classified as available-for-sale are reported at fair value utilizing Level 2 inputs. For these securities, the Company obtains fair value measurements from an independent pricing service. 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 security’s terms and conditions, among other things. In order to ensure the fair values are consistent with ASC Topic 820, the Company periodically checks the fair values by comparing them to another pricing source, such as Bloomberg. The availability of pricing confirms Level 2 classification in the fair value hierarchy. The third-party pricing service is subject to an annual review of internal controls (SSAE 16), which is made available for the Company’s review. In certain cases where Level 1 or Level 2 inputs are not available, securities are classified within Level 3 of the hierarchy. The Company’s investment in U.S. Treasury securities, if any, is reported at fair value utilizing Level 1 inputs. The remainder of the Company’s available-for-sale securities are reported at fair value utilizing Level 2 inputs. Derivative instruments – The Company’s derivative instruments are reported at fair value utilizing Level 2 inputs. The Company obtains fair value measurements from dealer quotes. Other assets and liabilities held for sale – The Company’s other assets and liabilities held for sale are reported at fair value utilizing Level 3 inputs. See Note 4 - Other assets and other liabilities held for sale. The following table sets forth the Company’s financial assets by level within the fair value hierarchy that were measured at fair value on a recurring basis as of December 31, 2018 and 2017 . Fair Value Measurements (In thousands) Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2018 Available-for-sale securities U.S. Government agencies $ 154,301 $ — $ 154,301 $ — Mortgage-backed securities 1,522,900 — 1,522,900 — States and political subdivisions 314,843 — 314,843 — Other securities 159,708 — 159,708 — Other assets held for sale 1,790 — — 1,790 Derivative asset 6,242 — 6,242 — Other liabilities held for sale (162 ) — — (162 ) Derivative liability (5,283 ) — (5,283 ) — December 31, 2017 Available-for-sale securities U.S. Government agencies $ 139,724 $ — $ 139,724 $ — Mortgage-backed securities 1,187,317 — 1,187,317 — States and political subdivisions 143,165 — 143,165 — Other securities 119,311 — 119,311 — Other assets held for sale 165,780 — — 165,780 Derivative asset 3,634 — 3,634 — Other liabilities held for sale (157,366 ) — — (157,366 ) Derivative liability (3,068 ) — (3,068 ) — Certain financial assets and liabilities are measured at fair value on a nonrecurring basis; that is, 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 liabilities measured at fair value on a nonrecurring basis include the following: Impaired loans (collateral dependent) – Loan impairment is reported when full payment under the loan terms is not expected. Allowable methods for determining the amount of impairment include estimating fair value using the fair value of the collateral for collateral-dependent loans. If the impaired loan is identified as collateral dependent, then the fair value method of measuring the amount of impairment is utilized. This method requires obtaining a current independent appraisal of the collateral and applying a discount factor to the value. A portion of the allowance for loan losses is allocated to impaired loans if the value of such loans is deemed to be less than the unpaid balance. If these allocations cause the allowance for loan losses to require an increase, such increase is reported as a component of the provision for loan losses. Loan losses are charged against the allowance when management believes the uncollectability of a loan is confirmed. Impaired loans that are collateral dependent are classified within Level 3 of the fair value hierarchy when impairment is determined using the fair value method. Appraisals are updated at renewal, if not more frequently, for all collateral dependent loans that are deemed impaired by way of impairment testing. Impairment testing is performed on all loans over $1.5 million rated Substandard or worse, all existing impaired loans regardless of size and all TDRs. All collateral dependent impaired loans meeting these thresholds have had updated appraisals or internally prepared evaluations within the last one to two years and these updated valuations are considered in the quarterly review and discussion of the corporate Special Asset Committee. On targeted CRE loans, appraisals/internally prepared valuations may be updated before the typical 1-3 year balloon/maturity period. If an updated valuation results in decreased value, a specific (ASC 310) impairment is placed against the loan, or a partial charge-down is initiated, depending on the circumstances and anticipation of the loan’s ability to remain a going concern, possibility of foreclosure, certain market factors, etc. Foreclosed assets and other real estate owned – Foreclosed assets and other real estate owned are reported at fair value, less estimated costs to sell. At foreclosure, if the fair value, less estimated costs to sell, of the real estate acquired is less than the Company’s recorded investment in the related loan, a write-down is recognized through a charge to the allowance for loan losses. Additionally, valuations are periodically performed by management and any subsequent reduction in value is recognized by a charge to income. The fair value of foreclosed assets and other real estate owned is estimated using Level 3 inputs based on unobservable market data. As of December 31, 2018 and 2017 , the fair value of foreclosed assets and other real estate owned less estimated costs to sell was $25.6 million and $32.1 million , respectively. The significant unobservable inputs (Level 3) used in the fair value measurement of collateral for collateral-dependent impaired loans and foreclosed assets primarily relate to the specialized discounting criteria applied to the borrower’s reported amount of collateral. The amount of the collateral discount depends upon the condition and marketability of the collateral, as well as other factors which may affect the collectability of the loan. Management’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset. It is reasonably possible that a change in the estimated fair value for instruments measured using Level 3 inputs could occur in the future. As the Company’s primary objective in the event of default would be to liquidate the collateral to settle the outstanding balance of the loan, collateral that is less marketable would receive a larger discount. During the reported periods, collateral discounts ranged from 10% to 40% for commercial and residential real estate collateral. Mortgage loans held for sale – Mortgage loans held for sale are reported at fair value if, on an aggregate basis, the fair value of the loans is less than cost. In determining whether the fair value of loans held for sale is less than cost when quoted market prices are not available, the Company may consider outstanding investor commitments, discounted cash flow analyses with market assumptions or the fair value of the collateral if the loan is collateral dependent. Such loans are classified within either Level 2 or Level 3 of the fair value hierarchy. Where assumptions are made using significant unobservable inputs, such loans held for sale are classified as Level 3. At December 31, 2018 and 2017 , the aggregate fair value of mortgage loans held for sale exceeded their cost. Accordingly, no mortgage loans held for sale were marked down and reported at fair value. The following table sets forth the Company’s financial assets by level within the fair value hierarchy that were measured at fair value on a nonrecurring basis as of December 31, 2018 and 2017 . Fair Value Measurements Using (In thousands) Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2018 Impaired loans (1) (2) (collateral dependent) $ 17,789 $ — $ — $ 17,789 Foreclosed assets and other real estate owned (1) 23,714 — — 23,714 December 31, 2017 Impaired loans (1) (2) (collateral dependent) $ 11,229 $ — $ — $ 11,229 Foreclosed assets and other real estate owned (1) 24,093 — — 24,093 ______________________ (1) These amounts represent the resulting carrying amounts on the Consolidated Balance Sheets for impaired collateral dependent loans and foreclosed assets and other real estate owned for which fair value re-measurements took place during the period. (2) Specific allocations of $2,738,000 and $2,195,000 were related to the impaired collateral dependent loans for which fair value re-measurements took place during the periods ended December 31, 2018 and 2017 , respectively. ASC Topic 825, Financial Instruments , requires disclosure in annual financial statements of the fair value of financial assets and financial liabilities, including those financial assets and financial liabilities that are not measured and reported at fair value on a recurring basis or nonrecurring basis. The following methods and assumptions were used to estimate the fair value of each class of financial instruments not previously disclosed. Cash and cash equivalents – The carrying amount for cash and cash equivalents approximates fair value (Level 1). Interest bearing balances due from banks – The fair value of interest bearing balances due from banks – time is estimated using a discounted cash flow calculation that applies the rates currently offered on deposits of similar remaining maturities (Level 2). Held-to-maturity securities – Fair values for held-to-maturity securities equal quoted market prices, if available, such as for highly liquid government bonds (Level 1). If quoted market prices are not available, fair values are estimated based on quoted market prices of similar securities. For these securities, the Company obtains fair value measurements from an independent pricing service. 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 security’s terms and conditions, among other things (Level 2). In certain cases where Level 1 or Level 2 inputs are not available, securities are classified within Level 3 of the hierarchy. Loans – The fair value of 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. Additional factors considered include the type of loan and related collateral, variable or fixed rate, classification status, remaining term, interest rate, historical delinquencies, loan to value ratios, current market rates and remaining loan balance. The loans were grouped together according to similar characteristics and were treated in the aggregate when applying various valuation techniques. The discount rates used for loans were based on current market rates for new originations of similar loans. Estimated credit losses were also factored into the projected cash flows of the loans. As of December 31, 2018, the fair value of loans is also estimated on an exit price basis incorporating the above factors (Level 3). Deposits – The fair value of demand deposits, savings accounts and money market deposits is the amount payable on demand at the reporting date (i.e., their carrying amount) (Level 2). The fair value of fixed-maturity time deposits is estimated using a discounted cash flow calculation that applies the rates currently offered for deposits of similar remaining maturities (Level 3). Federal Funds purchased, securities sold under agreement to repurchase and short-term debt – The carrying amount for Federal funds purchased, securities sold under agreement to repurchase and short-term debt are a reasonable estimate of fair value (Level 2). Other borrowings – For short-term instruments, the carrying amount is a reasonable estimate of fair value. For long-term debt, rates currently available to the Company for debt with similar terms and remaining maturities are used to estimate the fair value (Level 2). Subordinated debentures – The fair value of subordinated debentures is estimated using the rates that would be charged for subordinated debentures of similar remaining maturities (Level 2). Accrued interest receivable/payable – The carrying amounts of accrued interest approximated fair value (Level 2). Commitments to extend credit, letters of credit and lines of credit – The fair value of commitments is estimated using the fees currently charged to enter into similar agreements, taking into account the remaining terms of the agreements and the present creditworthiness of the counterparties. For fixed rate loan commitments, fair value also considers the difference between current levels of interest rates and the committed rates. The fair values of letters of credit and lines of credit are based on fees currently charged for similar agreements or on the estimated cost to terminate or otherwise settle the obligations with the counterparties at the reporting date. The fair value of a financial instrument is the current amount that would be exchanged between willing parties, other than in a forced liquidation. Fair value is best determined based upon quoted market prices. However, in many instances, there are no quoted market prices for the Company’s various financial instruments. In cases where quoted market prices are not available, fair values are based on estimates using present value or other valuation techniques. Those techniques are significantly affected by the assumptions used, including the discount rate and estimates of future cash flows. Accordingly, the fair value estimates may not be realized in an immediate settlement of the instrument. The estimated fair values, and related carrying amounts, of the Company’s financial instruments are as follows: Carrying Fair Value Measurements (In thousands) Amount Level 1 Level 2 Level 3 Total December 31, 2018 Financial assets: Cash and cash equivalents $ 833,458 $ 833,458 $ — $ — $ 833,458 Interest bearing balances due from banks - time 4,934 — 4,934 — 4,934 Held-to-maturity securities 289,194 — 290,830 — 290,830 Mortgage loans held for sale 26,799 — — 26,799 26,799 Interest receivable 49,938 — 49,938 — 49,938 Legacy loans, net 8,373,789 — — 8,280,690 8,280,690 Loans acquired, net 3,292,783 — — 3,256,174 3,256,174 Financial liabilities: Non-interest bearing transaction accounts 2,672,405 — 2,672,405 — 2,672,405 Interest bearing transaction accounts and savings deposits 6,830,191 — 6,830,191 — 6,830,191 Time deposits 2,896,156 — — 2,872,342 2,872,342 Federal funds purchased and securities sold under agreements to repurchase 95,792 — 95,792 — 95,792 Other borrowings 1,345,450 — 1,342,868 — 1,342,868 Subordinated notes and debentures 353,950 — 355,812 — 355,812 Interest payable 9,897 — 9,897 — 9,897 December 31, 2017 Financial assets: Cash and cash equivalents $ 598,042 $ 598,042 $ — $ — $ 598,042 Interest bearing balances due from banks - time 3,314 — 3,314 — 3,314 Held-to-maturity securities 368,058 — 373,298 — 373,298 Mortgage loans held for sale 24,038 — — 24,038 24,038 Interest receivable 43,528 — 43,528 — 43,528 Legacy loans, net 5,663,941 — — 5,646,505 5,646,505 Loans acquired, net 5,074,076 — — 5,058,455 5,058,455 Financial liabilities: Non-interest bearing transaction accounts 2,665,249 — 2,665,249 — 2,665,249 Interest bearing transaction accounts and savings deposits 6,494,896 — 6,494,896 — 6,494,896 Time deposits 1,932,730 — — 1,915,539 1,915,539 Federal funds purchased and securities sold under agreements to repurchase 122,444 — 122,444 — 122,444 Other borrowings 1,380,024 — 1,381,365 — 1,381,365 Subordinated debentures 140,565 — 136,474 — 136,474 Interest payable 4,564 — 4,564 — 4,564 The fair value of commitments to extend credit, letters of credit and lines of credit is not presented since management believes the fair value to be insignificant.

Commitments and Credit Risk

Commitments and Credit Risk	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Credit Risk	COMMITMENTS AND CREDIT RISK The Company grants agri-business, commercial and residential loans to customers primarily throughout Arkansas, Colorado, Kansas, Missouri, Oklahoma, Tennessee and Texas, along with credit card loans to customers throughout the United States. Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since a portion of the commitments may expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. Each customer’s creditworthiness is evaluated on a case-by-case basis. The amount of collateral obtained, if deemed necessary, is based on management’s credit evaluation of the counterparty. Collateral held varies, but may include accounts receivable, inventory, property, plant and equipment, commercial real estate and residential real estate. At December 31, 2018 , the Company had outstanding commitments to extend credit aggregating approximately $560,863,000 and $3,455,471,000 for credit card commitments and other loan commitments, respectively. At December 31, 2017 , the Company had outstanding commitments to extend credit aggregating approximately $564,592,000 and $3,086,696,000 for credit card commitments and other loan commitments, respectively. Standby letters of credit are conditional commitments issued by the Company to guarantee the performance of a customer to a third party. Those guarantees are primarily issued to support public and private borrowing arrangements, including commercial paper, bond financing and similar transactions. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loans to customers. The Company had total outstanding letters of credit amounting to $39,101,000 and $47,621,000 at December 31, 2018 and 2017 , respectively, with terms ranging from 9 months to 15 years. At December 31, 2018 and 2017 , the Company had no deferred revenue under standby letter of credit agreements. At December 31, 2018 , the Company did not have concentrations of 5% or more of the investment portfolio in bonds issued by a single municipality.

New Accounting Standards

New Accounting Standards	12 Months Ended
	Dec. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Standards	NEW ACCOUNTING STANDARDS Recently Adopted Accounting Standards Stock Compensation: Scope of Modification Accounting - In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”), that provides clarity and reduces both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, to a change to the terms or conditions of a share-based payment award. An entity may change the terms or conditions of a share-based payment award for many different reasons, and the nature and effect of the change can vary significantly. The guidance clarifies which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting and the guidance should be applied prospectively to an award modified on or after the adoption date. ASU 2017-09 is effective for interim and annual reporting periods beginning after December 15, 2017, with early adoption permitted. Currently, the Company has not modified any existing awards nor has any plans to do so, therefore the adoption of ASU 2017-09 has not had a material effect on the Company’s results of operations, financial position or disclosures. Statement of Cash Flows - In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”), designed to address the diversity in how certain cash receipts and cash payments are presented and classified in the statement of cash flows, including debt prepayment or extinguishment costs, settlement of certain debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, and distributions received from equity method investees. The amendments also provide guidance on when an entity should separate or aggregate cash flows based on the predominance principle. The effective date is for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The new standard is required to be applied retrospectively, but may be applied prospectively if retrospective application would be impracticable. The adoption of 2016-15 did not have a material impact on the Company’s results of operations, financial position or disclosures since the amendment applies to the classification of cash flows. The adoption did not have a material impact on the consolidated statement of cash flows. Financial Assets and Financial Liabilities - In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”), that makes changes primarily affecting the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, the FASB clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. In February 2018, the FASB issued 2018-03 that clarified certain guidance and contained narrow scope amendments. The effective date is for fiscal periods beginning after December 15, 2017, including interim periods within those fiscal years. ASU 2016-01 did not have a material impact on the Company’s results of operations or financial position. However, this new guidance requires the disclosed estimated fair value of the Company’s loan portfolio to be based on an exit price calculation, which considers liquidity, credit and nonperformance risk of its loans. The adoption of 2016-01 did not have a material impact on the Company’s fair value disclosures. Revenue Recognition - In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”), that outlines a single comprehensive revenue recognition model for entities to follow in accounting for revenue from contracts with customers. The core principle of this revenue model is that an entity should recognize revenue for the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to receive for those goods or services. In July 2015, the FASB issued ASU No. 2015-14, deferring the effective date to annual and interim periods beginning after December 15, 2017. The guidance does not apply to revenue associated with financial instruments, including loans and securities that are accounted for under other US GAAP, which comprises a significant portion of the Company’s revenue stream. However, the updated guidance affects the revenue recognition pattern for certain revenue streams, including service charges on deposit accounts, gains/losses on sale of other real estate owned (“OREO”), and trust income. The adoption of this standard did not have a material effect on the Company’s results of operations, financial position or disclosures. See Note 1 for additional information. Recently Issued Accounting Standards Cloud Computing Arrangements - In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract (“ASU 2018-15”), that amends the definition of a hosting arrangement and requires a customer in a hosting arrangement that is a service contract to capitalize certain implementation costs as if the arrangement was an internal-use software project. The internal-use software guidance states that only qualifying costs incurred during the application development stage can be capitalized. The effective date is for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted. Entities have the option to apply the guidance prospectively to all implementation costs incurred after the date of adoption or retrospectively in accordance with the applicable guidance. At the time of adoption, entities will be required to disclose the nature of its hosting arrangements that are service contracts and provide disclosures as if the deferred implementation costs were a separate, major depreciable asset class. The Company is beginning to evaluate its cloud computing arrangements and has not yet determined how it will apply or the impact of this new standard. Fair Value Measurement Disclosures - In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), that eliminates, amends and adds disclosure requirements for fair value measurements. These amendments are part of FASB’s disclosure review project and they are expected to reduce costs for preparers while providing more decision-useful information for financial statement users. The eliminated disclosure requirements include the 1) the amount of, and reasons for, transfers between Level 1 and Level 2 of the fair value hierarchy; 2) the policy of timing of transfers between levels of the fair value hierarchy; and 3) the valuation processes for Level 3 fair value measurements. Among other modifications, the amended disclosure requirements remove the term “at a minimum” from the phrase “an entity shall disclose at a minimum” to promote the appropriate exercise of discretion by entities and clarifies that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date. Under the new disclosure requirements, entities must disclose the changes in unrealized gains or losses included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact this standard will have on its fair value disclosures. Derivatives and Hedging: Targeted Improvements - In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities (“ASU 2017-12”), that changes both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results in order to better align a company’s risk management activities and financial reporting for hedging relationships. In summary, this amendment 1) expands the types of transactions eligible for hedge accounting; 2) eliminates the separate measurement and presentation of hedge ineffectiveness; 3) simplifies the requirements around the assessment of hedge effectiveness; 4) provides companies more time to finalize hedge documentation; and 5) enhances presentation and disclosure requirements. The effective date is for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted. All transition requirements and elections should be applied to existing hedging relationships on the date of adoption and the effects should be reflected as of the beginning of the fiscal year of adoption. The Company has evaluated the impact this standard will have on its results of operations, financial position or disclosures, and it is not expected to have a material impact. Goodwill Impairment - In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), that eliminates Step 2 from the goodwill impairment test which required entities to compare the implied fair value of goodwill to its carrying amount. Under the amendments, the goodwill impairment will be measured as the excess of the reporting unit’s carrying amount over its fair value. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The effective date is for fiscal years beginning after December 15, 2019, with early adoption permitted for interim or annual impairment tests beginning in 2017. ASU 2017-04 is not expected to have a material effect on the Company’s results of operations, financial position or disclosures. Credit Losses on Financial Instruments - In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires earlier measurement of credit losses, expands the range of information considered in determining expected credit losses and enhances disclosures. The main objective of ASU 2016-13 is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments replace the incurred loss impairment methodology in current US GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The effective date for these amendments is for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company has formed a cross functional team that continues to assess its data and system needs and evaluate the potential impact of adopting the new guidance. The Company anticipates a significant change in the processes and procedures to calculate the loan losses, including changes in assumptions and estimates to consider expected credit losses over the life of the loan versus the current accounting practice that utilizes the incurred loss model. In December 2018, the Federal Reserve, Office of the Comptroller of the Currency and Federal Deposit Insurance Corporation issued a final rule revising regulatory capital rules in anticipation of the adoption of ASU 2016-13 that provides an option to phase in the day-one impact on earnings and tier one capital. Due to this final rule from the regulatory agencies, the Company is researching and studying options for recording a one-time adjustment or structuring any capital impact over an allowable period of time. The Company has not yet determined the magnitude of any such adjustment or the overall impact on its results of operations, financial position or disclosures. However, the Company is continuing its efforts in developing processes and procedures to ensure it is fully compliant at the required adoption date. Among other things, the Company continues to gather data and develop forecast models for asset quality, loan balances, and portfolio net charge-offs and is working with the selected model vendor to produce parallel calculations through the year leading up to implementation. Model inputs began in the fourth quarter 2018 with additional inputs and scenarios to be modeled throughout 2019 with focus on calculating a potential range of financial impact. Leases - In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), that establishes the principles to report transparent and economically neutral information about the assets and liabilities that arise from leases. The new guidance results in a more consistent representation of the rights and obligations arising from leases by requiring lessees to recognize the lease asset and lease liabilities that arise from leases in the statement of financial position and to disclose qualitative and quantitative information about lease transactions, such as information about variable lease payments and options to renew and terminate leases. The effective date is for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. ASU 2016-02 requires entities to adopt the new lease standard using a modified retrospective transition method, meaning an entity initially applies the new lease standard at the beginning of the earliest period presented in the financial statements. Due to complexities associated with using this method, in July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements , to relieve entities of the requirement to present prior comparative years’ results when they adopt the new lease standard and giving entities the option to recognize the cumulative effect of applying the new standard as an adjustment to the opening balance of retained earnings. The Company has loaded all of the identified lease contracts that will need to be measured and reported in the statement of financial position into its selected lease administrative system. Adoption of ASU 2016-02 is expected to result in the recognition of right-of-use assets of $32.0 million and right-of-use liabilities of $32.0 million on the statement of financial position with no material impact to the results of operations. The Company has elected to adopt the guidance using the optional transition method, which allows for a modified retrospective method of adoption with a cumulative effect adjustment to retained earnings without restating comparable periods. The Company also plans to elect the relief package of practical expedients for which there is no requirement to reassess existence of leases, their classification, and initial direct costs as well as an exemption for short-term leases with a term of less than one year, whereby the Company does not recognize a lease liability or right-of-use asset on the statement of financial position but instead recognizes lease payments as an expense over the lease term as appropriate. Presently, the Company is not aware of any other changes to the Accounting Standards Codification that will have a material impact on the Company’s present or future financial position or results of operations.

Contingent Liabilities

Contingent Liabilities	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contingent Liabilities	CONTINGENT LIABILITIES The Company and/or its subsidiaries have various unrelated legal proceedings, which, in the aggregate, are not expected to have a material adverse effect on the financial position of the Company and its subsidiaries.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY The Company’s subsidiary bank is subject to legal limitations on dividends that can be paid to the parent company without prior approval of the applicable regulatory agencies. The approval of the Commissioner of the Arkansas State Bank Department is required if the total of all dividends declared by an Arkansas state bank in any calendar year exceeds seventy-five percent ( 75% ) of the total of its net profits, as defined, for that year combined with seventy-five percent ( 75% ) of its retained net profits of the preceding year. At December 31, 2018 , the Company’s subsidiary bank had approximately $32.3 million available for payment of dividends to the Company, without prior regulatory approval. The Company’s subsidiary bank is subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on our financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, we must meet specific capital guidelines that involve quantitative measures of our assets, liabilities and certain off-balance-sheet items as calculated under regulatory accounting practices. Our capital amounts and classifications are also subject to qualitative judgments by the regulators about components, risk weightings and other factors. Effective January 1, 2015, the Company and the subsidiary bank became subject to new capital regulations (the “Basel III Capital Rules”) adopted by the Federal Reserve in July 2013 establishing a new comprehensive capital framework for U.S. Banks. The Basel III Capital Rules substantially revise the risk-based capital requirements applicable to bank holding companies and depository institutions compared to the previous U.S. risk-based capital rules. Full compliance with all of the final rule’s requirements will be phased in over a multi-year schedule. The final rules include a new common equity Tier 1 capital to risk-weighted assets (CET1) ratio of 4.5% and a common equity Tier 1 capital conservation buffer of 2.5% of risk-weighted assets. CET1 generally consists of common stock; retained earnings; accumulated other comprehensive income and certain minority interests; all subject to applicable regulatory adjustments and deductions. The new capital conservation buffer requirement began being phased in beginning on January 1, 2016 when a buffer greater than 0.625% of risk-weighted assets was required, which amount will increase each year until the buffer requirement is fully implemented on January 1, 2019. Quantitative measures established by regulation to ensure capital adequacy require the Company to maintain minimum amounts and ratios (set forth in the table below) of total, Tier 1 and common equity Tier 1 capital (as defined in the regulations) to risk-weighted assets (as defined) and of Tier 1 capital (as defined) to average assets (as defined). As of December 31, 2018 , the Company and its subsidiary bank met all capital adequacy requirements under the Basel III Capital Rules, and management believes the Company and its subsidiary bank would meet all capital rules on a fully-phased in basis if such requirements were currently effective. As of the most recent notification from regulatory agencies, the subsidiary bank was well capitalized under the regulatory framework for prompt corrective action. To be categorized as well capitalized, the Company and its subsidiary bank must maintain minimum total risk-based, Tier 1 risk-based, common equity Tier 1 risk-based and Tier 1 leverage ratios as set forth in the table. There are no conditions or events since that notification that management believes have changed the institutions’ categories. The Company’s and the subsidiary bank’s actual capital amounts and ratios are presented in the following table. Bank SNB and Southwest Bank were merged into Simmons Bank during 2018. Actual Minimum For Capital Adequacy Purposes To Be Well Capitalized Under Prompt Corrective Action Provision (In thousands) Amount Ratio (%) Amount Ratio (%) Amount Ratio (%) December 31, 2018 Total Risk-Based Capital Ratio Simmons First National Corporation $ 1,778,938 13.3 $ 1,070,038 8.0 N/A Simmons Bank 1,532,864 11.5 1,066,340 8.0 1,332,925 10.0 Tier 1 Risk-Based Capital Ratio Simmons First National Corporation 1,361,380 10.2 800,812 6.0 N/A Simmons Bank 1,469,260 11.0 801,415 6.0 1,068,553 8.0 Common Equity Tier 1 Capital Ratio Simmons First National Corporation 1,361,380 10.2 600,609 4.5 N/A Simmons Bank 1,469,260 11.0 601,061 4.5 868,199 6.5 Tier 1 Leverage Ratio Simmons First National Corporation 1,361,380 8.8 618,809 4.0 N/A Simmons Bank 1,469,260 9.5 618,636 4.0 773,295 5.0 December 31, 2017 Total Risk-Based Capital Ratio Simmons First National Corporation $ 1,388,970 11.4 $ 974,716 8.0 N/A Simmons Bank 877,728 12.1 580,316 8.0 725,395 10.0 Bank SNB 259,077 10.9 190,148 8.0 237,685 10.0 Southwest Bank 297,164 11.0 216,119 8.0 270,149 10.0 Tier 1 Risk-Based Capital Ratio Simmons First National Corporation 1,199,457 9.8 734,361 6.0 N/A Simmons Bank 835,787 11.5 436,063 6.0 581,417 8.0 Bank SNB 255,360 10.7 143,193 6.0 190,923 8.0 Southwest Bank 294,874 10.9 162,316 6.0 216,421 8.0 Common Equity Tier 1 Capital Ratio Simmons First National Corporation 1,199,457 9.8 550,771 4.5 N/A Simmons Bank 835,787 11.5 327,047 4.5 472,401 6.5 Bank SNB 255,360 10.7 107,394 4.5 155,125 6.5 Southwest Bank 294,874 10.9 121,737 4.5 175,842 6.5 Tier 1 Leverage Ratio Simmons First National Corporation 1,199,457 9.2 521,503 4.0 N/A Simmons Bank 835,787 9.2 363,386 4.0 454,232 5.0 Bank SNB 255,360 10.1 101,133 4.0 126,416 5.0 Southwest Bank 294,874 12.2 96,680 4.0 120,850 5.0

Condensed Financial Information

Condensed Financial Information (Parent Company Only)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Condensed Financial Information (Parent Company Only)	CONDENSED FINANCIAL INFORMATION (PARENT COMPANY ONLY) Condensed Balance Sheets December 31, 2018 and 2017 (In thousands) 2018 2017 ASSETS Cash and cash equivalents $ 219,063 $ 19,101 Investment securities 2,848 2,789 Investments in wholly-owned subsidiaries 2,368,870 2,288,687 Loans 774 993 Intangible assets, net 133 133 Premises and equipment 5,804 10,369 Other assets 29,974 31,181 TOTAL ASSETS $ 2,627,466 $ 2,353,253 LIABILITIES Short-term debt $ — $ 75,000 Long-term debt 353,950 183,947 Other liabilities 27,082 9,742 Total liabilities 381,032 268,689 STOCKHOLDERS’ EQUITY Common stock 923 920 Surplus 1,597,944 1,586,034 Undivided profits 674,941 514,874 Accumulated other comprehensive loss Unrealized depreciation on available-for-sale securities, net of income taxes of ($9,686) and ($6,108) at December 31, 2018 and 2017 respectively (27,374 ) (17,264 ) Total stockholders’ equity 2,246,434 2,084,564 TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY $ 2,627,466 $ 2,353,253 Condensed Statements of Income Years Ended December 31, 2018 , 2017 and 2016 (In thousands) 2018 2017 2016 INCOME Dividends from subsidiaries $ 145,980 $ 69,107 $ 83,710 Other income 658 4,111 2,465 Income 146,638 73,218 86,175 EXPENSE 32,714 32,234 21,990 Income before income taxes and equity in undistributed net income of subsidiaries 113,924 40,984 64,185 Provision for income taxes (10,732 ) (12,311 ) (7,557 ) Income before equity in undistributed net income of subsidiaries 124,656 53,295 71,742 Equity in undistributed net income of subsidiaries 91,057 39,645 25,072 NET INCOME 215,713 92,940 96,814 Preferred stock dividends — — 24 NET INCOME AVAILABLE TO COMMON SHAREHOLDERS $ 215,713 $ 92,940 $ 96,790 Condensed Statements of Comprehensive Income Years Ended December 31, 2018 , 2017 and 2016 (In thousands) 2018 2017 2016 NET INCOME $ 215,713 $ 92,940 $ 96,814 OTHER COMPREHENSIVE INCOME (LOSS) Equity in other comprehensive (loss) income of subsidiaries (10,110 ) 964 (12,547 ) COMPREHENSIVE INCOME $ 205,603 $ 93,904 $ 84,267 Condensed Statements of Cash Flows Years Ended December 31, 2018 , 2017 and 2016 (In thousands) 2018 2017 2016 CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 215,713 $ 92,940 $ 96,814 Items not requiring (providing) cash Stock-based compensation expense 9,725 10,681 3,418 Depreciation and amortization 880 1,183 700 Deferred income taxes 26 1,190 (2,526 ) Equity in undistributed net income of bank subsidiaries (91,057 ) (39,645 ) (25,072 ) Changes in Other assets 1,524 8,585 2,816 Other liabilities 17,340 (6,769 ) (1,358 ) Net cash provided by operating activities 154,151 68,165 74,792 CASH FLOWS FROM INVESTING ACTIVITIES Net originations of loans 219 90 (1,710 ) Net proceeds from (purchases of) premises and equipment 3,342 (18 ) (6,896 ) Repayment of (advances to) subsidiaries 2,667 (15,000 ) — Proceeds from maturities of available-for-sale securities 152 42 1,973 Purchases of available-for-sale securities (211 ) (2,752 ) (3 ) Cash paid in business combinations — (100,468 ) (35,048 ) Other, net (1,903 ) — — Net cash provided by (used in) investing activities 4,266 (118,106 ) (41,684 ) CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from issuance of subordinated notes 326,355 — — Issuance (repayment) of long-term debt, net (231,352 ) 8,014 (4,544 ) Issuance of common stock, net 2,188 2,878 4,938 Dividends paid on preferred stock — — (24 ) Dividends paid on common stock (55,646 ) (35,116 ) (28,743 ) Redemption of preferred stock — — (30,852 ) Net cash provided by (used in) financing activities 41,545 (24,224 ) (59,225 ) INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS 199,962 (74,165 ) (26,117 ) CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR 19,101 93,266 119,383 CASH AND CASH EQUIVALENTS, END OF YEAR $ 219,063 $ 19,101 $ 93,266

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Nature of Operations and Principles of Consolidation	Nature of Operations and Principles of Consolidation Simmons First National Corporation (the “Company”) is primarily engaged in providing a full range of banking services to individual and corporate customers through its subsidiaries and their branch banks with offices. We are headquartered in Pine Bluff, Arkansas and conduct banking operations in communities throughout Arkansas, Colorado, Kansas, Missouri, Oklahoma, Tennessee and Texas. We offer consumer, real estate and commercial loans, checking, savings and time deposits from our 191 financial centers conveniently located throughout our market areas. Additionally, we offer specialized products and services such as credit cards, trust and fiduciary services, investments, agricultural finance lending, equipment lending, insurance and small business administration (“SBA”) lending. The Company is subject to regulation of certain federal and state agencies and undergoes periodic examinations by those regulatory authorities. The consolidated financial statements include the accounts of the Company and its subsidiaries. Significant intercompany accounts and transactions have been eliminated in consolidation.
Operating Segments	Operating Segments Operating segments are components of an enterprise about which separate financial information is available that is regularly evaluated by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company is organized on a divisional basis. Each of the divisions provide a group of similar community banking services, including such products and services as loans; time deposits, checking and savings accounts; personal and corporate trust services; credit cards; investment management; insurance; and securities and investment services. Loan products include consumer, real estate, commercial, agricultural, equipment and SBA lending. The individual bank divisions have similar operating and economic characteristics. While the chief operating decision maker monitors the revenue streams of the various products, services, branch locations and divisions, operations are managed, financial performance is evaluated, and management makes decisions on how to allocate resources on a Company-wide basis. Accordingly, the divisions are considered by management to be aggregated into one reportable operating segment, community banking. The Company also considers its trust, investment and insurance services to be operating segments. Information on these segments is not reported separately since they do not meet the quantitative thresholds under Accounting Standards Codification (“ASC”) Topic 280-10-50-12.
Use of Estimates	Use of Estimates The preparation of financial statements, in accordance with accounting principles generally accepted in the United States (“US GAAP”), requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, income and expenses and disclosure of contingent assets and liabilities. The estimates and assumptions used in the accompanying consolidated financial statements are based upon management’s evaluation of the relevant facts and circumstances as of the date of the consolidated financial statements and actual results may differ from these estimates. Material estimates that are particularly susceptible to significant change relate to the determination of the allowance for loan losses, the valuation of real estate acquired in connection with foreclosures or in satisfaction of loans and the valuation of acquired loans. Management obtains independent appraisals for significant properties in connection with the determination of the allowance for loan losses and the valuation of foreclosed assets.
Reclassifications	Reclassifications Various items within the accompanying consolidated financial statements for previous years have been reclassified to provide more comparative information. These reclassifications were not material to the consolidated financial statements.
Cash Equivalents	Cash Equivalents The Company considers all liquid investments with original maturities of three months or less to be cash equivalents. For purposes of the consolidated statements of cash flows, cash and cash equivalents are considered to include cash and non-interest bearing balances due from banks, interest bearing balances due from banks and federal funds sold and securities purchased under agreements to resell.
Investment Securities	Investment Securities Held-to-maturity securities, which include any security for which the Company has the positive intent and ability to hold until maturity, are carried at historical cost adjusted for amortization of premiums and accretion of discounts. Premiums and discounts are amortized and accreted, respectively, to interest income using the constant yield method over the period to maturity. Available-for-sale securities, which include any security for which the Company has no immediate plan to sell but which may be sold in the future, are carried at fair value. Realized gains and losses, based on specifically identified amortized cost of the individual security, are included in other income. Unrealized gains and losses are recorded, net of related income tax effects, in stockholders’ equity. Premiums and discounts are amortized and accreted, respectively, to interest income using the constant yield method over the period to maturity. Trading securities, which include any security held primarily for near-term sale, are carried at fair value. Gains and losses on trading securities are included in other income. The Company applies accounting guidance related to recognition and presentation of other-than-temporary impairment under ASC Topic 320-10. When the Company does not intend to sell a debt security, and it is more likely than not, the Company will not have to sell the security before recovery of its cost basis, it recognizes the credit component of an other-than-temporary impairment of a debt security in earnings and the remaining portion in other comprehensive income. For held-to-maturity debt securities, the amount of an other-than-temporary impairment recorded in other comprehensive income for the noncredit portion of a previous other-than-temporary impairment is amortized prospectively over the remaining life of the security on the basis of the timing of future estimated cash flows of the security. As a result of this guidance, the Company’s consolidated statements of income reflect the full impairment (that is, the difference between the security’s amortized cost basis and fair value) on debt securities that the Company intends to sell or would more likely than not be required to sell before the expected recovery of the amortized cost basis. For available-for-sale and held-to-maturity debt securities that management has no intent to sell and believes that it more likely than not will not be required to sell prior to recovery, only the credit loss component of the impairment is recognized in earnings, while the noncredit loss is recognized in accumulated other comprehensive income. The credit loss component recognized in earnings is identified as the amount of principal cash flows not expected to be received over the remaining term of the security as projected based on cash flow projections.
Mortgage Loans Held For Sale	Mortgage Loans Held For Sale Mortgage Loans Held for Sale are carried at fair value which is determined on an aggregate basis. Adjustments to fair value are recognized monthly and reflected in earnings. The Company regularly sells mortgages into the capital markets to mitigate the effects of interest rate volatility during the period from the time an interest rate lock commitment (IRLC) is issued until the IRLC funds creating a mortgage loan held for sale and its subsequent sale into the secondary/capital markets. Loan sales are typically executed on a mandatory basis. Under a mandatory commitment, the Company agrees to deliver a specified dollar amount with predetermined terms by a certain date. Generally, the commitment is not loan specific, and any combination of loans can be delivered into the outstanding commitment provided the terms fall within the parameters of the commitment. Upon failure to deliver, the Company is subject to fees based on market movement. The IRLCs are derivative instruments; their fair values at December 31, 2018 and 2017 were not material. Gains and losses resulting from sales of mortgage loans are recognized when the respective loans are sold to correspondent lenders, investors or aggregators. Gains and losses are determined by the difference between the sale price and the carrying amount in the loans sold, net of discounts collected, or premiums paid. Hedge instruments are, likewise, carried at fair value and associated gains/losses are realized at time of settlement.
Loans	Loans Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-offs are reported at their outstanding principal adjusted for any loans charged off, the allowance for loan losses and any unamortized deferred fees or costs on originated loans and unamortized premiums or discounts on purchased loans. For loans amortized at cost, interest income is accrued based on the unpaid principal balance. Loan origination fees, net of certain direct origination costs, as well as premiums and discounts, are deferred and amortized as a level yield adjustment over the respective term of the loan. The accrual of interest on loans, except on certain government guaranteed loans, is discontinued at the time the loan is 90 days past due unless the credit is well-secured and in process of collection. Past due status is based on contractual terms of the loan. In all cases, loans are placed on nonaccrual or charged off at an earlier date if collection of principal or interest is considered doubtful. Discounts and premiums on purchased residential real estate loans are amortized to income using the interest method over the remaining period to contractual maturity, adjusted for anticipated prepayments. Discounts and premiums on purchased consumer loans are recognized over the expected lives of the loans using methods that approximate the interest method. For discussion of the Company’s accounting for acquired loans, see Acquisition Accounting, Acquired Loans later in this section.
Allowance for Loan Losses	Allowance for Loan Losses The allowance for loan losses is management’s estimate of probable losses in the loan portfolio. Loan losses are charged against the allowance when management believes the uncollectability of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. Allocations to the allowance for loan losses are categorized as either general reserves or specific reserves. The allowance for loan losses is calculated monthly based on management’s assessment of several factors such as (1) historical loss experience based on volumes and types, (2) volume and trends in delinquencies and nonaccruals, (3) lending policies and procedures including those for loan losses, collections and recoveries, (4) national, state and local economic trends and conditions, (5) external factors and pressure from competition, (6)the experience, ability and depth of lending management and staff, (7) seasoning of new products obtained and new markets entered through acquisition and (8) other factors and trends that will affect specific loans and categories of loans. The Company establishes general allocations for each major loan category. This category also includes allocations to loans which are collectively evaluated for loss such as credit cards, one-to-four family owner occupied residential real estate loans and other consumer loans. General reserves have been established, based upon the aforementioned factors and allocated to the individual loan categories. Specific reserves are provided on loans that are considered impaired when it is probable that we will not receive all amounts due according to the contractual terms of the loan, including scheduled principal and interest payments. This includes loans that are delinquent 90 days or more, nonaccrual loans and certain other loans identified by management. Certain other loans identified by management consist of performing loans where management expects that the Company will not receive all amounts due according to the contractual terms of the loan, including scheduled principal and interest payments. Specific reserves are accrued for probable losses on specific loans evaluated for impairment for which the basis of each loan, including accrued interest, exceeds the discounted amount of expected future collections of interest and principal or, alternatively, the fair value of loan collateral. Accrual of interest is discontinued and interest accrued and unpaid is removed at the time such amounts are delinquent 90 days unless management is aware of circumstances which warrant continuing the interest accrual. Interest is recognized for nonaccrual loans only upon receipt and only after all principal amounts are current according to the terms of the contract. Management’s evaluation of the allowance for loan losses is inherently subjective as it requires material estimates. The actual amounts of loan losses realized in the near term could differ from the amounts estimated in arriving at the allowance for loan losses reported in the financial statements.
Reserve for Unfunded Commitments	Reserve for Unfunded Commitments In addition to the allowance for loan losses, the Company has established a reserve for unfunded commitments, classified in other liabilities. This reserve is maintained at a level sufficient to absorb losses arising from unfunded loan commitments. The adequacy of the reserve for unfunded commitments is determined monthly based on methodology similar to the Company’s methodology for determining the allowance for loan losses. Net adjustments to the reserve for unfunded commitments are included in other non-interest expense.
Acquisition Accounting, Acquired Loans	Acquisition Accounting, Acquired Loans The Company accounts for its acquisitions under ASC Topic 805, Business Combinations , which requires the use of the acquisition method of accounting. All identifiable assets acquired, including loans, are recorded at fair value. No allowance for loan losses related to the acquired loans is recorded on the acquisition date as the fair value of the loans acquired incorporates assumptions regarding credit risk. Loans acquired are recorded at fair value in accordance with the fair value methodology prescribed in ASC Topic 820. The fair value estimates associated with the loans include estimates related to expected prepayments and the amount and timing of undiscounted expected principal, interest and other cash flows. The Company evaluates non-impaired loans acquired in accordance with the provisions of ASC Topic 310-20, Nonrefundable Fees and Other Costs . The fair value discount on these loans is accreted into interest income over the weighted average life of the loans using a constant yield method. The Company evaluates purchased impaired loans in accordance with the provisions of ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality . Purchased loans are considered impaired if there is evidence of credit deterioration since origination and if it is probable that not all contractually required payments will be collected. For impaired loans accounted for under ASC Topic 310-30, the Company continues to estimate cash flows expected to be collected on purchased credit impaired loans. The Company evaluates at each balance sheet date whether the present value of the purchased credit impaired loans determined using the effective interest rates has decreased significantly and if so, recognize a provision for loan loss in our consolidated statement of income. For any significant increases in cash flows expected to be collected, the Company adjusts the amount of accretable yield recognized on a prospective basis over the remaining life of the purchased credit impaired loan. For further discussion of our acquisition and loan accounting, see Note 2, Acquisitions, and Note 6, Loans Acquired.
Trust Assets	Trust Assets Trust assets (other than cash deposits) held by the Company in fiduciary or agency capacities for its customers are not included in the accompanying consolidated balance sheets since such items are not assets of the Company.
Premises and Equipment	Premises and Equipment Depreciable assets are stated at cost less accumulated depreciation. Depreciation is charged to expense using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are capitalized and amortized by the straight-line method over the terms of the respective leases or the estimated useful lives of the improvements, whichever is shorter.
Foreclosed Assets Held For Sale	Foreclosed Assets Held For Sale Assets acquired by foreclosure or in settlement of debt and held for sale are valued at estimated fair value as of the date of foreclosure, and a related valuation allowance is provided for estimated costs to sell the assets. Management evaluates the value of foreclosed assets held for sale periodically and increases the valuation allowance for any subsequent declines in fair value. Changes in the valuation allowance are charged or credited to other expense.
Bank Owned Life Insurance	Bank Owned Life Insurance The Company maintains bank-owned life insurance policies on certain current and former employees and directors, which are recorded at their cash surrender values as determined by the insurance carriers. The appreciation in the cash surrender value of the policies is recognized as a component of non-interest income in the Company’s consolidated statements of income.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill represents the excess of the cost of an acquisition over the fair value of the net assets acquired. Other intangible assets represent purchased assets that also lack physical substance but can be separately distinguished from goodwill because of contractual or other legal rights or because the asset is capable of being sold or exchanged either on its own or in combination with a related contract, asset or liability. The Company performs an annual goodwill impairment test, and more frequently if circumstances warrant, in accordance with ASC Topic 350, Intangibles – Goodwill and Other . ASC Topic 350 requires that goodwill and intangible assets that have indefinite lives be reviewed for impairment annually, or more frequently if certain conditions occur. Intangible assets with finite lives are amortized over the estimated life of the asset, and are reviewed for impairment whenever events or changes in circumstances indicated that the carrying value may not be recoverable. Impairment losses, if any, will be recorded as operating expenses.
Derivative Financial Instruments	Derivative Financial Instruments The Company may enter into derivative contracts for the purposes of managing exposure to interest rate risk to meet the financing needs of its customers. The Company records all derivatives on the balance sheet at fair value. In an effort to meet the financing needs of its customers, the Company has entered into limited fair value hedges. Fair value hedges include interest rate swap agreements on fixed rate loans. To qualify for hedge accounting, derivatives must be highly effective at reducing the risk associated with the exposure being hedged and must be designated as a hedge at the point of inception of the derivative contract. For derivatives designated as hedging the exposure to changes in the fair value of the hedged item, the gain or loss is recognized in earnings in the period of change together with the offsetting loss or gain of the hedging instrument. The fair value hedges are considered to be highly effective and any hedge ineffectiveness was deemed not material. Fair value adjustments related to cash flow hedges are recorded in other comprehensive income and are reclassified to earnings when the hedged transaction is reflected in earnings.
Securities Sold Under Agreements to Repurchase	Securities Sold Under Agreements to Repurchase The Company sells securities under agreements to repurchase to meet customer needs for sweep accounts. At the point funds deposited by customers become investable, those funds are used to purchase securities owned by the Company and held in its general account with the designation of Customers’ Securities. A third party maintains control over the securities underlying overnight repurchase agreements. The securities involved in these transactions are generally U.S. Treasury or Federal Agency issues. Securities sold under agreements to repurchase generally mature on the banking day following that on which the investment was initially purchased and are treated as collateralized financing transactions which are recorded at the amounts at which the securities were sold plus accrued interest. Interest rates and maturity dates of the securities involved vary and are not intended to be matched with funds from customers.
Revenue from Contracts with Customers	Revenue from Contracts with Customers ASC Topic 606, Revenue from Contracts with Customers , applies to all contracts with customers to provide goods or services in the ordinary course of business. However, Topic 606 specifically does not apply to revenue related to financial instruments, guarantees, insurance contracts, leases, or nonmonetary exchanges. Given these scope exceptions, interest income recognition and measurement related to loans and investments securities, the Company’s two largest sources of revenue, are not accounted for under Topic 606. Also, the Company does not use Topic 606 to account for gains or losses on its investments in securities, loans, and derivatives due to the scope exceptions. Certain revenue streams, such as service charges on deposit accounts, gains or losses on the sale of OREO, and trust income, fall under the scope of Topic 606 and the Company must recognize revenue at an amount that reflects the consideration to which the Company expects to be entitled in exchange for transferring goods or services to a customer. Topic 606 is applied using five steps: 1) identify the contract with the customer, 2) identify the performance obligations in the contract, 3) determine the transaction price, 4) allocate the transaction price to the performance obligations in the contract, and 5) recognize revenue when (or as) the entity satisfies a performance obligation. The Company has evaluated the nature of all contracts with customers that fall under the scope of Topic 606 and determined that further disaggregation of revenue from contracts with customers into categories was not necessary. There has not been significant revenue recognized in the current reporting periods resulting from performance obligations satisfied in previous periods. In addition, there has not been a significant change in timing of revenues received from customers. A description of performance obligations for each type of contract with customers is as follows: Service charges on deposit accounts – The Company’s primary source of funding comes from deposit accounts with its customers. Customers pay certain fees to access their cash on deposit including, but not limited to, non-transactional fees such as account maintenance, dormancy or statement rendering fees, and certain transaction-based fees such as ATM, wire transfer, overdraft or returned check fees. The Company generally satisfies its performance obligations as services are rendered. The transaction prices are fixed, and are charged either on a periodic basis or based on activity. Sale of OREO – In the normal course of business, the Company will enter into contracts with customers to sell OREO, which has generally been foreclosed upon by the Company. The Company generally satisfies its performance obligation upon conveyance of property from the Company to the customer, generally by way of an executed agreement. The transaction price is fixed, and on occasion the Company will finance a portion of the proceeds the customers uses to purchase the property. These properties are generally sold without recourse or warranty. Trust Income – The Company enters into contracts with its customers to manage assets for investment, and/or transact on their accounts. The Company generally satisfies its performance obligations as services are rendered. The management fee is a fixed percentage-based fee calculated upon the average balance of assets under management and is charged to customers on a monthly basis.
Bankcard Fee Income	Bankcard Fee Income – Periodic bankcard fees, net of direct origination costs, are recognized as revenue on a straight-line basis over the period the fee entitles the cardholder to use the card.
Income Taxes	Income Taxes The Company accounts for income taxes in accordance with income tax accounting guidance in ASC Topic 740, Income Taxes . The income tax accounting guidance results in two components of income tax expense: current and deferred. Current income tax expense reflects taxes to be paid or refunded for the current period by applying the provisions of the enacted tax law to the taxable income or excess of deductions over revenues. The Company determines deferred income taxes using the liability (or balance sheet) method. Under this method, the net deferred tax asset or liability is based on the tax effects of the differences between the book and tax bases of assets and liabilities, and enacted changes in tax rates and laws are recognized in the period in which they occur. Deferred income tax expense results from changes in deferred tax assets and liabilities between periods. Deferred tax assets are recognized if it is more likely than not, based on the technical merits, that the tax position will be realized or sustained upon examination. The term more likely than not means a likelihood of more than 50 percent; the terms examined and upon examination also include resolution of the related appeals or litigation processes, if any. A tax position that meets the more-likely-than-not recognition threshold is initially and subsequently measured as the largest amount of tax benefit that has a greater than 50 percent likelihood of being realized upon settlement with a taxing authority that has full knowledge of all relevant information. The determination of whether or not a tax position has met the more-likely-than-not recognition threshold considers the facts, circumstances and information available at the reporting date and is subject to management’s judgment. Deferred tax assets are reduced by a valuation allowance if, based on the weight of evidence available, it is more likely than not that some portion or all of a deferred tax asset will not be realized. The Company files consolidated income tax returns with its subsidiaries.
Earnings Per Share	Earnings Per Share Basic earnings per share are computed based on the weighted average number of shares outstanding during each year. Diluted earnings per share are computed using the weighted average common shares and all potential dilutive common shares outstanding during the period. All share and per share amounts have been restated to reflect the effect of the two -for-one stock split during February 2018.
Stock-Based Compensation	Stock-Based Compensation The Company has adopted various stock-based compensation plans. The plans provide for the grant of incentive stock options, nonqualified stock options, stock appreciation rights and bonus stock awards. Pursuant to the plans, shares are reserved for future issuance by the Company, upon exercise of stock options or awarding of bonus shares granted to directors, officers and other key employees. In accordance with ASC Topic 718, Compensation – Stock Compensation , the fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model that uses various assumptions. This model requires the input of highly subjective assumptions, changes to which can materially affect the fair value estimate. For additional information, see Note 14, Employee Benefit Plans.
New Accounting Standards	Recently Adopted Accounting Standards Stock Compensation: Scope of Modification Accounting - In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”), that provides clarity and reduces both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, to a change to the terms or conditions of a share-based payment award. An entity may change the terms or conditions of a share-based payment award for many different reasons, and the nature and effect of the change can vary significantly. The guidance clarifies which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting and the guidance should be applied prospectively to an award modified on or after the adoption date. ASU 2017-09 is effective for interim and annual reporting periods beginning after December 15, 2017, with early adoption permitted. Currently, the Company has not modified any existing awards nor has any plans to do so, therefore the adoption of ASU 2017-09 has not had a material effect on the Company’s results of operations, financial position or disclosures. Statement of Cash Flows - In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”), designed to address the diversity in how certain cash receipts and cash payments are presented and classified in the statement of cash flows, including debt prepayment or extinguishment costs, settlement of certain debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, and distributions received from equity method investees. The amendments also provide guidance on when an entity should separate or aggregate cash flows based on the predominance principle. The effective date is for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The new standard is required to be applied retrospectively, but may be applied prospectively if retrospective application would be impracticable. The adoption of 2016-15 did not have a material impact on the Company’s results of operations, financial position or disclosures since the amendment applies to the classification of cash flows. The adoption did not have a material impact on the consolidated statement of cash flows. Financial Assets and Financial Liabilities - In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”), that makes changes primarily affecting the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, the FASB clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. In February 2018, the FASB issued 2018-03 that clarified certain guidance and contained narrow scope amendments. The effective date is for fiscal periods beginning after December 15, 2017, including interim periods within those fiscal years. ASU 2016-01 did not have a material impact on the Company’s results of operations or financial position. However, this new guidance requires the disclosed estimated fair value of the Company’s loan portfolio to be based on an exit price calculation, which considers liquidity, credit and nonperformance risk of its loans. The adoption of 2016-01 did not have a material impact on the Company’s fair value disclosures. Revenue Recognition - In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”), that outlines a single comprehensive revenue recognition model for entities to follow in accounting for revenue from contracts with customers. The core principle of this revenue model is that an entity should recognize revenue for the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to receive for those goods or services. In July 2015, the FASB issued ASU No. 2015-14, deferring the effective date to annual and interim periods beginning after December 15, 2017. The guidance does not apply to revenue associated with financial instruments, including loans and securities that are accounted for under other US GAAP, which comprises a significant portion of the Company’s revenue stream. However, the updated guidance affects the revenue recognition pattern for certain revenue streams, including service charges on deposit accounts, gains/losses on sale of other real estate owned (“OREO”), and trust income. The adoption of this standard did not have a material effect on the Company’s results of operations, financial position or disclosures. See Note 1 for additional information. Recently Issued Accounting Standards Cloud Computing Arrangements - In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract (“ASU 2018-15”), that amends the definition of a hosting arrangement and requires a customer in a hosting arrangement that is a service contract to capitalize certain implementation costs as if the arrangement was an internal-use software project. The internal-use software guidance states that only qualifying costs incurred during the application development stage can be capitalized. The effective date is for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted. Entities have the option to apply the guidance prospectively to all implementation costs incurred after the date of adoption or retrospectively in accordance with the applicable guidance. At the time of adoption, entities will be required to disclose the nature of its hosting arrangements that are service contracts and provide disclosures as if the deferred implementation costs were a separate, major depreciable asset class. The Company is beginning to evaluate its cloud computing arrangements and has not yet determined how it will apply or the impact of this new standard. Fair Value Measurement Disclosures - In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), that eliminates, amends and adds disclosure requirements for fair value measurements. These amendments are part of FASB’s disclosure review project and they are expected to reduce costs for preparers while providing more decision-useful information for financial statement users. The eliminated disclosure requirements include the 1) the amount of, and reasons for, transfers between Level 1 and Level 2 of the fair value hierarchy; 2) the policy of timing of transfers between levels of the fair value hierarchy; and 3) the valuation processes for Level 3 fair value measurements. Among other modifications, the amended disclosure requirements remove the term “at a minimum” from the phrase “an entity shall disclose at a minimum” to promote the appropriate exercise of discretion by entities and clarifies that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date. Under the new disclosure requirements, entities must disclose the changes in unrealized gains or losses included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact this standard will have on its fair value disclosures. Derivatives and Hedging: Targeted Improvements - In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities (“ASU 2017-12”), that changes both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results in order to better align a company’s risk management activities and financial reporting for hedging relationships. In summary, this amendment 1) expands the types of transactions eligible for hedge accounting; 2) eliminates the separate measurement and presentation of hedge ineffectiveness; 3) simplifies the requirements around the assessment of hedge effectiveness; 4) provides companies more time to finalize hedge documentation; and 5) enhances presentation and disclosure requirements. The effective date is for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted. All transition requirements and elections should be applied to existing hedging relationships on the date of adoption and the effects should be reflected as of the beginning of the fiscal year of adoption. The Company has evaluated the impact this standard will have on its results of operations, financial position or disclosures, and it is not expected to have a material impact. Goodwill Impairment - In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), that eliminates Step 2 from the goodwill impairment test which required entities to compare the implied fair value of goodwill to its carrying amount. Under the amendments, the goodwill impairment will be measured as the excess of the reporting unit’s carrying amount over its fair value. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The effective date is for fiscal years beginning after December 15, 2019, with early adoption permitted for interim or annual impairment tests beginning in 2017. ASU 2017-04 is not expected to have a material effect on the Company’s results of operations, financial position or disclosures. Credit Losses on Financial Instruments - In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires earlier measurement of credit losses, expands the range of information considered in determining expected credit losses and enhances disclosures. The main objective of ASU 2016-13 is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments replace the incurred loss impairment methodology in current US GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The effective date for these amendments is for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company has formed a cross functional team that continues to assess its data and system needs and evaluate the potential impact of adopting the new guidance. The Company anticipates a significant change in the processes and procedures to calculate the loan losses, including changes in assumptions and estimates to consider expected credit losses over the life of the loan versus the current accounting practice that utilizes the incurred loss model. In December 2018, the Federal Reserve, Office of the Comptroller of the Currency and Federal Deposit Insurance Corporation issued a final rule revising regulatory capital rules in anticipation of the adoption of ASU 2016-13 that provides an option to phase in the day-one impact on earnings and tier one capital. Due to this final rule from the regulatory agencies, the Company is researching and studying options for recording a one-time adjustment or structuring any capital impact over an allowable period of time. The Company has not yet determined the magnitude of any such adjustment or the overall impact on its results of operations, financial position or disclosures. However, the Company is continuing its efforts in developing processes and procedures to ensure it is fully compliant at the required adoption date. Among other things, the Company continues to gather data and develop forecast models for asset quality, loan balances, and portfolio net charge-offs and is working with the selected model vendor to produce parallel calculations through the year leading up to implementation. Model inputs began in the fourth quarter 2018 with additional inputs and scenarios to be modeled throughout 2019 with focus on calculating a potential range of financial impact. Leases - In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), that establishes the principles to report transparent and economically neutral information about the assets and liabilities that arise from leases. The new guidance results in a more consistent representation of the rights and obligations arising from leases by requiring lessees to recognize the lease asset and lease liabilities that arise from leases in the statement of financial position and to disclose qualitative and quantitative information about lease transactions, such as information about variable lease payments and options to renew and terminate leases. The effective date is for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. ASU 2016-02 requires entities to adopt the new lease standard using a modified retrospective transition method, meaning an entity initially applies the new lease standard at the beginning of the earliest period presented in the financial statements. Due to complexities associated with using this method, in July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements , to relieve entities of the requirement to present prior comparative years’ results when they adopt the new lease standard and giving entities the option to recognize the cumulative effect of applying the new standard as an adjustment to the opening balance of retained earnings. The Company has loaded all of the identified lease contracts that will need to be measured and reported in the statement of financial position into its selected lease administrative system. Adoption of ASU 2016-02 is expected to result in the recognition of right-of-use assets of $32.0 million and right-of-use liabilities of $32.0 million on the statement of financial position with no material impact to the results of operations. The Company has elected to adopt the guidance using the optional transition method, which allows for a modified retrospective method of adoption with a cumulative effect adjustment to retained earnings without restating comparable periods. The Company also plans to elect the relief package of practical expedients for which there is no requirement to reassess existence of leases, their classification, and initial direct costs as well as an exemption for short-term leases with a term of less than one year, whereby the Company does not recognize a lease liability or right-of-use asset on the statement of financial position but instead recognizes lease payments as an expense over the lease term as appropriate. Presently, the Company is not aware of any other changes to the Accounting Standards Codification that will have a material impact on the Company’s present or future financial position or results of operations.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Notes Tables
Schedule of Earnings Per Share, Basic and Diluted	The computation of per share earnings is as follows: (In thousands, except per share data) 2018 2017 2016 Net income available to common shareholders $ 215,713 $ 92,940 $ 96,790 Average common shares outstanding 92,268 69,385 61,291 Average potential dilutive common shares 562 468 636 Average diluted common shares 92,830 69,853 61,927 Basic earnings per share $ 2.34 $ 1.34 $ 1.58 Diluted earnings per share $ 2.32 $ 1.33 $ 1.56

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Summary of Assets Acquired and Liabilities Assumed	A summary, at fair value, of the assets acquired and liabilities assumed in the First Texas transaction, as of the acquisition date, is as follows: (In thousands) Acquired from First Texas Fair Value Adjustments Fair Value Assets Acquired Cash and due from banks $ 59,277 $ — $ 59,277 Investment securities 81,114 (596 ) 80,518 Loans acquired 2,246,212 (37,834 ) 2,208,378 Allowance for loan losses (20,864 ) 20,664 (200 ) Premises and equipment 24,864 10,123 34,987 Bank owned life insurance 7,190 — 7,190 Goodwill 37,227 (37,227 ) — Core deposit intangible — 7,328 7,328 Other assets 18,263 11,485 29,748 Total assets acquired $ 2,453,283 $ (26,057 ) $ 2,427,226 Liabilities Assumed Deposits: Non-interest bearing transaction accounts $ 74,410 $ — $ 74,410 Interest bearing transaction accounts and savings deposits 1,683,298 — 1,683,298 Time deposits 124,233 (283 ) 123,950 Total deposits 1,881,941 (283 ) 1,881,658 Securities sold under agreement to repurchase 50,000 — 50,000 Other borrowings 235,000 — 235,000 Subordinated debentures 30,323 589 30,912 Accrued interest and other liabilities 11,727 1,669 13,396 Total liabilities assumed 2,208,991 1,975 2,210,966 Equity 244,292 (244,292 ) — Total equity assumed 244,292 (244,292 ) — Total liabilities and equity assumed $ 2,453,283 $ (242,317 ) $ 2,210,966 Net assets acquired 216,260 Purchase price 457,103 Goodwill $ 240,843 A summary, at fair value, of the assets acquired and liabilities assumed in the Citizens transaction, as of the acquisition date, is as follows: (In thousands) Acquired from Citizens Fair Value Adjustments Fair Value Assets Acquired Cash and due from banks $ 131,467 $ (351 ) $ 131,116 Federal funds sold 10,000 — 10,000 Investment securities 61,987 1 61,988 Loans acquired 350,361 (9,511 ) 340,850 Allowance for loan losses (4,313 ) 4,313 — Foreclosed assets 4,960 (1,518 ) 3,442 Premises and equipment 6,746 1,339 8,085 Bank owned life insurance 6,632 — 6,632 Core deposit intangible — 5,075 5,075 Other intangibles — 591 591 Other assets 17,364 6 17,370 Total assets acquired $ 585,204 $ (55 ) $ 585,149 Liabilities Assumed Deposits: Non-interest bearing transaction accounts $ 109,281 $ — $ 109,281 Interest bearing transaction accounts and savings deposits 204,912 — 204,912 Time deposits 195,664 — 195,664 Total deposits 509,857 — 509,857 Securities sold under agreement to repurchase 13,233 — 13,233 FHLB borrowings 4,000 47 4,047 Accrued interest and other liabilities 3,558 1,530 5,088 Total liabilities assumed 530,648 1,577 532,225 Equity 54,556 (54,556 ) — Total equity assumed 54,556 (54,556 ) — Total liabilities and equity assumed $ 585,204 $ (52,979 ) $ 532,225 Net assets acquired 52,924 Purchase price 76,300 Goodwill $ 23,376 A summary, at fair value, of the assets acquired and liabilities assumed in the OKSB transaction, as of the acquisition date, is as follows: (In thousands) Acquired from OKSB Fair Value Adjustments Fair Value Assets Acquired Cash and due from banks $ 79,517 $ — $ 79,517 Investment securities 485,468 (1,295 ) 484,173 Loans acquired 2,039,524 (43,071 ) 1,996,453 Allowance for loan losses (26,957 ) 26,957 — Foreclosed assets 6,284 (1,127 ) 5,157 Premises and equipment 21,210 5,457 26,667 Bank owned life insurance 28,704 — 28,704 Goodwill 13,545 (13,545 ) — Core deposit intangible 1,933 40,191 42,124 Other intangibles 3,806 — 3,806 Other assets 33,455 (9,141 ) 24,314 Total assets acquired $ 2,686,489 $ 4,426 $ 2,690,915 (In thousands) Acquired from OKSB Fair Value Adjustments Fair Value Liabilities Assumed Deposits: Non-interest bearing transaction accounts $ 485,971 $ — $ 485,971 Interest bearing transaction accounts and savings deposits 869,252 — 869,252 Time deposits 613,345 (2,213 ) 611,132 Total deposits 1,968,568 (2,213 ) 1,966,355 Securities sold under agreement to repurchase 11,256 — 11,256 Other borrowings 347,000 — 347,000 Subordinated debentures 46,393 — 46,393 Accrued interest and other liabilities 17,440 5,364 22,804 Total liabilities assumed 2,390,657 3,151 2,393,808 Equity 295,832 (295,832 ) — Total equity assumed 295,832 (295,832 ) — Total liabilities and equity assumed $ 2,686,489 $ (292,681 ) $ 2,393,808 Net assets acquired 297,107 Purchase price 526,251 Goodwill $ 229,144 (In thousands) Acquired from Hardeman Fair Value Adjustments Fair Value Liabilities Assumed Deposits: Non-interest bearing transaction accounts $ 76,555 $ — $ 76,555 Interest bearing transaction accounts and savings deposits 214,872 — 214,872 Time deposits 97,917 (368 ) 97,549 Total deposits 389,344 (368 ) 388,976 Securities sold under agreement to repurchase 17,163 — 17,163 Other borrowings 3,000 — 3,000 Subordinated debentures 6,702 — 6,702 Accrued interest and other liabilities 1,891 1,924 3,815 Total liabilities assumed 418,100 1,556 419,656 Equity 50,729 (50,729 ) — Total equity assumed 50,729 (50,729 ) — Total liabilities and equity assumed $ 468,829 $ (49,173 ) $ 419,656 Net assets acquired 43,268 Purchase price 72,639 Goodwill $ 29,371
Pro Forma Information	The pro forma financial information is not necessarily indicative of the results of operations if the acquisitions had been effective as of this date. (In thousands, except per share data) 2017 2016 Revenue (1) $ 654,358 $ 620,461 Net income $ 130,947 $ 136,199 Diluted earnings per share $ 1.43 $ 1.52 _________________________ (1) Net interest income plus non-interest income.

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investment Securities	The amortized cost and fair value of investment securities that are classified as held-to-maturity (“HTM”) and available-for-sale (“AFS”) are as follows: Years Ended December 31, 2018 2017 (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Estimated Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Estimated Fair Value Held-to-Maturity U.S. Government agencies $ 16,990 $ — $ (49 ) $ 16,941 $ 46,945 $ 7 $ (228 ) $ 46,724 Mortgage-backed securities 13,346 5 (412 ) 12,939 16,132 8 (287 ) 15,853 State and political subdivisions 256,863 3,029 (954 ) 258,938 301,491 5,962 (222 ) 307,231 Other securities 1,995 17 — 2,012 3,490 — — 3,490 Total HTM $ 289,194 $ 3,051 $ (1,415 ) $ 290,830 $ 368,058 $ 5,977 $ (737 ) $ 373,298 Available-for-Sale U.S. Government agencies $ 157,523 $ 518 $ (3,740 ) $ 154,301 $ 141,559 $ 116 $ (1,951 ) $ 139,724 Mortgage-backed securities 1,552,487 3,097 (32,684 ) 1,522,900 1,208,017 246 (20,946 ) 1,187,317 State and political subdivisions 320,142 171 (5,470 ) 314,843 144,642 532 (2,009 ) 143,165 Other securities 157,471 2,251 (14 ) 159,708 118,106 1,206 (1 ) 119,311 Total AFS $ 2,187,623 $ 6,037 $ (41,908 ) $ 2,151,752 $ 1,612,324 $ 2,100 $ (24,907 ) $ 1,589,517
Schedule of Unrealized Loss on Investments	The following table shows the gross unrealized losses and fair value of the Company’s investments with unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at: Less Than 12 Months 12 Months or More Total (In thousands) Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses December 31, 2018 Held-to-Maturity U.S. Government agencies $ 992 $ (2 ) $ 15,948 $ (47 ) $ 16,940 $ (49 ) Mortgage-backed securities — — 12,177 (412 ) 12,177 (412 ) State and political subdivisions 39,149 (208 ) 50,889 (746 ) 90,038 (954 ) Total HTM $ 40,141 $ (210 ) $ 79,014 $ (1,205 ) $ 119,155 $ (1,415 ) Available-for-Sale U.S. Government agencies $ 26,562 $ (221 ) $ 108,636 $ (3,519 ) $ 135,198 $ (3,740 ) Mortgage-backed securities 163,560 (1,146 ) 1,037,679 (31,538 ) 1,201,239 (32,684 ) State and political subdivisions 129,075 (1,406 ) 132,020 (4,064 ) 261,095 (5,470 ) Other securities 65 (13 ) 99 (1 ) 164 (14 ) Total AFS $ 319,262 $ (2,786 ) $ 1,278,434 $ (39,122 ) $ 1,597,696 $ (41,908 ) December 31, 2017 Held-to-Maturity U.S. Government agencies $ 11,961 $ (6 ) $ 32,778 $ (222 ) $ 44,739 $ (228 ) Mortgage-backed securities 5,471 (47 ) 8,946 (240 ) 14,417 (287 ) State and political subdivisions 40,299 (198 ) 1,887 (24 ) 42,186 (222 ) Total HTM $ 57,731 $ (251 ) $ 43,611 $ (486 ) $ 101,342 $ (737 ) Available-for-Sale U.S. Government agencies $ 91,988 $ (921 ) $ 25,742 $ (1,030 ) $ 117,730 $ (1,951 ) Mortgage-backed securities 510,770 (4,516 ) 609,329 (16,430 ) 1,120,099 (20,946 ) State and political subdivisions 25,049 (202 ) 75,404 (1,807 ) 100,453 (2,009 ) Other securities — — 99 (1 ) 99 (1 ) Total AFS $ 627,807 $ (5,639 ) $ 710,574 $ (19,268 ) $ 1,338,381 $ (24,907 )
Income Earned on Securities	Income earned on securities for the years ended December 31, 2018 , 2017 and 2016 , is as follows: (In thousands) 2018 2017 2016 Taxable: Held-to-maturity $ 2,157 $ 2,521 $ 3,778 Available-for-sale 40,926 25,996 17,928 Non-taxable: Held-to-maturity 7,424 8,693 10,641 Available-for-sale 6,811 2,905 1,132 Total $ 57,318 $ 40,115 $ 33,479
Investments Classified by Contractual Maturity Date	The amortized cost and estimated fair value by maturity of securities are shown in the following table. Securities are classified according to their contractual maturities without consideration of principal amortization, potential prepayments or call options. Accordingly, actual maturities may differ from contractual maturities. Held-to-Maturity Available-for-Sale (In thousands) Amortized Cost Fair Value Amortized Cost Fair Value One year or less $ 29,579 $ 29,515 $ 120 $ 119 After one through five years 60,564 60,514 35,518 34,923 After five through ten years 88,770 88,971 39,426 39,360 After ten years 96,935 98,891 407,815 400,011 Securities not due on a single maturity date 13,346 12,939 1,552,487 1,522,900 Other securities (no maturity) — — 152,257 154,439 Total $ 289,194 $ 290,830 $ 2,187,623 $ 2,151,752

Loans and Allowance for Loan _2

Loans and Allowance for Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Schedule of Categories of Loans	At December 31, 2018 , the Company’s loan portfolio was $11.72 billion , compared to $10.78 billion at December 31, 2017 . The various categories of loans are summarized as follows: (In thousands) 2018 2017 Consumer: Credit cards $ 204,173 $ 185,422 Other consumer 201,297 280,094 Total consumer 405,470 465,516 Real estate: Construction 1,300,723 614,155 Single family residential 1,440,443 1,094,633 Other commercial 3,225,287 2,530,824 Total real estate 5,966,453 4,239,612 Commercial: Commercial 1,774,909 825,217 Agricultural 164,514 148,302 Total commercial 1,939,423 973,519 Other 119,042 26,962 Loans 8,430,388 5,705,609 Loans acquired, net of discount and allowance (1) 3,292,783 5,074,076 Total loans $ 11,723,171 $ 10,779,685 _________________________ (1) See Note 6, Loans Acquired, for segregation of loans acquired by loan class. The following table reflects the carrying value of all loans acquired as of December 31, 2018 and 2017 : Loans Acquired At December 31, (In thousands) 2018 2017 Consumer: Other consumer $ 15,658 $ 51,467 Real estate: Construction 429,605 637,032 Single family residential 566,188 793,228 Other commercial 1,848,679 2,387,777 Total real estate 2,844,472 3,818,037 Commercial: Commercial 430,914 995,587 Agricultural 1,739 66,576 Total commercial 432,653 1,062,163 Other — 142,409 Total loans acquired (1) $ 3,292,783 $ 5,074,076 _________________________ (1) Loans acquired are reported net of a $95,000 and $418,000 allowance as of December 31, 2018 and 2017 , respectively.
Schedule of Nonaccrual Loans, Excluding Loans Acquired	Nonaccrual loans, excluding loans acquired, at December 31, 2018 and 2017 , segregated by class of loans, are as follows: (In thousands) 2018 2017 Consumer: Credit cards $ 296 $ 170 Other consumer 2,159 4,605 Total consumer 2,455 4,775 Real estate: Construction 1,269 2,242 Single family residential 11,939 13,431 Other commercial 7,205 16,054 Total real estate 20,413 31,727 Commercial: Commercial 10,049 6,980 Agricultural 1,284 2,160 Total commercial 11,333 9,140 Total $ 34,201 $ 45,642 Nonaccrual loans acquired, excluding purchased credit impaired loans accounted for under ASC Topic 310-30, segregated by class of loans, are as follows (see Note 5, Loans and Allowance for Loan Losses, for discussion of nonaccrual loans): (In thousands) December 31, 2018 December 31, 2017 Consumer: Other consumer $ 140 $ 334 Real estate: Construction 114 1,767 Single family residential 6,603 12,151 Other commercial 1,167 7,401 Total real estate 7,884 21,319 Commercial: Commercial 13,578 1,748 Agricultural 38 84 Total commercial 13,616 1,832 Total $ 21,640 $ 23,485
Schedule of Aging Analysis of Past Due Loans, Excluding Loans Acquired	An age analysis of past due loans, excluding loans acquired, segregated by class of loans, is as follows: (In thousands) Gross 30-89 Days Past Due 90 Days or More Past Due Total Past Due Current Total Loans 90 Days Past Due & Accruing December 31, 2018 Consumer: Credit cards $ 1,033 $ 506 $ 1,539 $ 202,634 $ 204,173 $ 209 Other consumer 4,264 896 5,160 196,137 201,297 4 Total consumer 5,297 1,402 6,699 398,771 405,470 213 Real estate: Construction 533 308 841 1,299,882 1,300,723 — Single family residential 7,769 4,127 11,896 1,428,547 1,440,443 — Other commercial 3,379 2,773 6,152 3,219,135 3,225,287 — Total real estate 11,681 7,208 18,889 5,947,564 5,966,453 — Commercial: Commercial 4,472 5,105 9,577 1,765,332 1,774,909 11 Agricultural 467 1,055 1,522 162,992 164,514 — Total commercial 4,939 6,160 11,099 1,928,324 1,939,423 11 Other — — — 119,042 119,042 — Total $ 21,917 $ 14,770 $ 36,687 $ 8,393,701 $ 8,430,388 $ 224 December 31, 2017 Consumer: Credit cards $ 707 $ 672 $ 1,379 $ 184,043 $ 185,422 $ 332 Other consumer 5,009 3,298 8,307 271,787 280,094 10 Total consumer 5,716 3,970 9,686 455,830 465,516 342 Real estate: Construction 411 1,210 1,621 612,534 614,155 — Single family residential 8,071 6,460 14,531 1,080,102 1,094,633 1 Other commercial 2,388 8,031 10,419 2,520,405 2,530,824 — Total real estate 10,870 15,701 26,571 4,213,041 4,239,612 1 Commercial: Commercial 1,523 6,125 7,648 817,569 825,217 — Agricultural 50 2,120 2,170 146,132 148,302 — Total commercial 1,573 8,245 9,818 963,701 973,519 — Other — — — 26,962 26,962 — Total $ 18,159 $ 27,916 $ 46,075 $ 5,659,534 $ 5,705,609 $ 343 An age analysis of past due loans acquired segregated by class of loans, is as follows (see Note 5, Loans and Allowance for Loan Losses, for discussion of past due loans): (In thousands) Gross 30-89 Days Past Due 90 Days or More Past Due Total Past Due Current Total Loans 90 Days Past Due & Accruing December 31, 2018 Consumer: Other consumer $ 337 $ 49 $ 386 $ 15,272 $ 15,658 $ 2 Real estate: Construction 8,283 27 8,310 421,295 429,605 — Single family residential 4,706 3,049 7,755 558,433 566,188 — Other commercial 168 577 745 1,847,934 1,848,679 — Total real estate 13,157 3,653 16,810 2,827,662 2,844,472 — Commercial: Commercial 1,302 9,542 10,844 420,070 430,914 — Agricultural 31 5 36 1,703 1,739 — Total commercial 1,333 9,547 10,880 421,773 432,653 — Total $ 14,827 $ 13,249 $ 28,076 $ 3,264,707 $ 3,292,783 $ 2 December 31, 2017 Consumer: Other consumer $ 889 $ 260 $ 1,149 $ 50,318 $ 51,467 $ 108 Real estate: Construction 2,577 1,448 4,025 633,007 637,032 279 Single family residential 12,936 3,302 16,238 776,990 793,228 126 Other commercial 17,176 5,647 22,823 2,364,954 2,387,777 2,565 Total real estate 32,689 10,397 43,086 3,774,951 3,818,037 2,970 Commercial: Commercial 2,344 1,039 3,383 992,204 995,587 67 Agricultural 51 — 51 66,525 66,576 — Total commercial 2,395 1,039 3,434 1,058,729 1,062,163 67 Other 15 — 15 142,394 142,409 — Total $ 35,988 $ 11,696 $ 47,684 $ 5,026,392 $ 5,074,076 $ 3,145
Schedule of Impaired Loans	Impaired loans, net of government guarantees and excluding loans acquired, segregated by class of loans, are as follows: (In thousands) Unpaid Contractual Principal Balance Recorded Investment With No Allowance Recorded Investment With Allowance Total Recorded Investment Related Allowance Average Investment in Impaired Loans Interest Income Recognized December 31, 2018 Consumer: Credit cards $ 296 $ 296 $ — $ 296 $ — $ 266 $ 85 Other consumer 2,311 2,159 — 2,159 — 3,719 112 Total consumer 2,607 2,455 — 2,455 — 3,985 197 Real estate: Construction 1,344 784 485 1,269 211 1,651 50 Single family residential 12,906 11,468 616 12,084 36 13,257 399 Other commercial 8,434 5,442 5,458 10,900 — 13,608 410 Total real estate 22,684 17,694 6,559 24,253 247 28,516 859 Commercial: Commercial 10,361 7,254 4,628 11,882 437 10,003 301 Agricultural 2,419 1,180 — 1,180 — 1,412 43 Total commercial 12,780 8,434 4,628 13,062 437 11,415 344 Total $ 38,071 $ 28,583 $ 11,187 $ 39,770 $ 684 $ 43,916 $ 1,400 December 31, 2017 Consumer: Credit cards $ 170 $ 170 $ — $ 170 $ — $ 268 $ 47 Other consumer 4,755 4,605 — 4,605 — 3,089 106 Total consumer 4,925 4,775 — 4,775 — 3,357 153 Real estate: Construction 2,522 1,347 895 2,242 249 2,711 93 Single family residential 14,347 12,725 706 13,431 53 12,904 443 Other commercial 22,308 6,732 9,133 15,865 36 18,624 639 Total real estate 39,177 20,804 10,734 31,538 338 34,239 1,175 Commercial: Commercial 9,954 4,306 2,269 6,575 — 11,670 400 Agricultural 3,278 1,035 — 1,035 — 1,522 52 Total commercial 13,232 5,341 2,269 7,610 — 13,192 452 Total $ 57,334 $ 30,920 $ 13,003 $ 43,923 $ 338 $ 50,788 $ 1,780
Schedule of Troubled Debt Restructuring	The following table presents a summary of troubled debt restructurings, excluding loans acquired, segregated by class of loans. Accruing TDR Loans Nonaccrual TDR Loans Total TDR Loans (Dollars in thousands) Number Balance Number Balance Number Balance December 31, 2018 Real estate: Construction — $ — 3 $ 485 3 $ 485 Single-family residential 6 230 10 616 16 846 Other commercial 2 3,306 2 1,027 4 4,333 Total real estate 8 3,536 15 2,128 23 5,664 Commercial: Commercial 4 2,833 6 718 10 3,551 Total commercial 4 2,833 6 718 10 3,551 Total 12 $ 6,369 21 $ 2,846 33 $ 9,215 December 31, 2017 Real estate: Construction — $ — 1 $ 420 1 $ 420 Single-family residential 4 141 15 954 19 1,095 Other commercial 4 4,322 5 3,712 9 8,034 Total real estate 8 4,463 21 5,086 29 9,549 Commercial: Commercial 5 2,644 6 745 11 3,389 Total commercial 5 2,644 6 745 11 3,389 Total 13 $ 7,107 27 $ 5,831 40 $ 12,938 The following table presents loans that were restructured as TDRs during the years ended December 31, 2018 and 2017 , excluding loans acquired, segregated by class of loans. Modification Type (Dollars in thousands) Number of Loans Balance Prior to TDR Balance at December 31, Change in Maturity Date Change in Rate Financial Impact on Date of Restructure Year Ended December 31, 2018 Consumer: Other consumer 1 $ 91 $ 91 $ 91 $ — $ — Total consumer 1 91 91 91 — — Real estate: Construction 1 99 98 98 — — Single-family residential 1 61 62 62 — — Other commercial 2 392 390 390 — 212 Total real estate 4 552 550 550 — 212 Commercial: Commercial 3 2,363 2,358 2,358 — 190 Total commercial 3 2,363 2,358 2,358 — 190 Total 8 $ 3,006 $ 2,999 $ 2,999 $ — $ 402 Year Ended December 31, 2017 Real estate: Construction 1 $ 456 $ 456 $ 456 $ — $ — Single-family residential 1 139 130 130 — — Other commercial 3 7,715 7,715 7,715 — 33 Total real estate 5 8,310 8,301 8,301 — 33 Commercial: Commercial 11 2,691 2,604 2,565 39 — Total commercial 11 2,691 2,604 2,565 39 — Total 16 $ 11,001 $ 10,905 $ 10,866 $ 39 $ 33
Summary of Loans by Credit Risk Rating	The following table presents a summary of loans by credit risk rating, segregated by class of loans. (In thousands) Risk Rate 1-4 Risk Rate 5 Risk Rate 6 Risk Rate 7 Risk Rate 8 Total December 31, 2018 Consumer: Credit cards $ 203,667 $ — $ 506 $ — $ — $ 204,173 Other consumer 198,840 — 2,457 — — 201,297 Total consumer 402,507 — 2,963 — — 405,470 Real estate: Construction 1,296,988 1,910 1,825 — — 1,300,723 Single family residential 1,420,052 1,628 18,528 235 — 1,440,443 Other commercial 3,193,289 17,169 14,829 — — 3,225,287 Total real estate 5,910,329 20,707 35,182 235 — 5,966,453 Commercial: Commercial 1,742,002 8,357 24,550 — — 1,774,909 Agricultural 162,824 75 1,615 — — 164,514 Total commercial 1,904,826 8,432 26,165 — — 1,939,423 Other 119,042 — — — — 119,042 Loans acquired 3,187,083 51,255 54,097 348 — 3,292,783 Total $ 11,523,787 $ 80,394 $ 118,407 $ 583 $ — $ 11,723,171 (In thousands) Risk Rate 1-4 Risk Rate 5 Risk Rate 6 Risk Rate 7 Risk Rate 8 Total December 31, 2017 Consumer: Credit cards $ 184,920 $ — $ 502 $ — $ — $ 185,422 Other consumer 275,160 — 4,934 — — 280,094 Total consumer 460,080 — 5,436 — — 465,516 Real estate: Construction 603,126 5,795 5,218 16 — 614,155 Single family residential 1,066,902 3,954 23,490 287 — 1,094,633 Other commercial 2,480,293 19,581 30,950 — — 2,530,824 Total real estate 4,150,321 29,330 59,658 303 — 4,239,612 Commercial: Commercial 736,377 74,254 14,402 50 134 825,217 Agricultural 146,065 24 2,190 23 — 148,302 Total commercial 882,442 74,278 16,592 73 134 973,519 Other 26,962 — — — — 26,962 Loans acquired 4,918,570 62,128 93,378 — — 5,074,076 Total $ 10,438,375 $ 165,736 $ 175,064 $ 376 $ 134 $ 10,779,685 The following table presents a summary of loans acquired by credit risk rating, segregated by class of loans (see Note 5, Loans and Allowance for Loan Losses, for discussion of loan risk rating). Loans accounted for under ASC Topic 310-30 are all included in Risk Rate 1-4 in this table. (In thousands) Risk Rate 1-4 Risk Rate 5 Risk Rate 6 Risk Rate 7 Risk Rate 8 Total December 31, 2018 Consumer: Other consumer $ 15,380 $ — $ 278 $ — $ — $ 15,658 Real estate: Construction 393,122 27,621 8,862 — — 429,605 Single family residential 553,460 2,081 10,299 348 — 566,188 Other commercial 1,822,179 9,137 17,363 — — 1,848,679 Total real estate 2,768,761 38,839 36,524 348 — 2,844,472 Commercial: Commercial 401,300 12,416 17,198 — — 430,914 Agricultural 1,642 — 97 — — 1,739 Total commercial 402,942 12,416 17,295 — — 432,653 Total $ 3,187,083 $ 51,255 $ 54,097 $ 348 $ — $ 3,292,783 December 31, 2017 Consumer: Other consumer $ 50,625 $ 21 $ 821 $ — $ — $ 51,467 Real estate: Construction 604,796 30,524 1,712 — — 637,032 Single family residential 770,954 2,618 19,656 — — 793,228 Other commercial 2,337,097 15,064 35,616 — — 2,387,777 Total real estate 3,712,847 48,206 56,984 — — 3,818,037 Commercial: Commercial 946,322 13,901 35,364 — — 995,587 Agricultural 66,367 — 209 — — 66,576 Total commercial 1,012,689 13,901 35,573 — — 1,062,163 Other 142,409 — — — — 142,409 Total $ 4,918,570 $ 62,128 $ 93,378 $ — $ — $ 5,074,076
Schedule of the Activity in the Allowance for Loan Losses	Activity in the allowance for loan losses for the year ended December 31, 2016 was as follows: (In thousands) Commercial Real Estate Credit Card Other Consumer and Other Total December 31, 2016 Balance, beginning of year (2) $ 5,985 $ 19,522 $ 3,893 $ 1,951 $ 31,351 Provision for loan losses (1) 5,345 9,461 2,174 2,459 19,439 Charge-offs (3,956 ) (7,517 ) (3,195 ) (1,975 ) (16,643 ) Recoveries 365 351 907 516 2,139 Net charge-offs (3,591 ) (7,166 ) (2,288 ) (1,459 ) (14,504 ) Balance, end of year (2) $ 7,739 $ 21,817 $ 3,779 $ 2,951 $ 36,286 _________________________ (1) Provision for loan losses of $626,000 attributable to loans acquired was excluded from this table for the year ended December 31, 2016 (total provision for loan losses for the year ended December 31, 2016 was $20,065,000 ). The $626,000 was subsequently charged-off, resulting in no increase to the ending balance in the allowance related to loans acquired. (2) Allowance for loan losses at December 31, 2016 includes $954,000 allowance for loans acquired (not shown in the table above). The total allowance for loan losses at December 31, 2016 was $37,240,000 . (In thousands) Commercial Real Estate Credit Card Other Consumer and Other Total December 31, 2018 Balance, beginning of year (2) $ 7,007 $ 27,281 $ 3,784 $ 3,596 $ 41,668 Provision for loan losses (1) 19,385 7,376 3,185 4,903 34,849 Charge-offs (6,623 ) (5,905 ) (4,051 ) (6,637 ) (23,216 ) Recoveries 745 991 1,005 557 3,298 Net charge-offs (5,878 ) (4,914 ) (3,046 ) (6,080 ) (19,918 ) Balance, end of year (2) $ 20,514 $ 29,743 $ 3,923 $ 2,419 $ 56,599 Period-end amount allocated to: Loans individually evaluated for impairment $ 437 $ 247 $ — $ — $ 684 Loans collectively evaluated for impairment 20,077 29,496 3,923 2,419 55,915 Balance, end of year (2) $ 20,514 $ 29,743 $ 3,923 $ 2,419 $ 56,599 December 31, 2017 Balance, beginning of year (2) $ 7,739 $ 21,817 $ 3,779 $ 2,951 $ 36,286 Provision for loan losses (1) 7,002 12,463 2,889 2,173 24,527 Charge-offs (7,837 ) (7,989 ) (3,905 ) (3,767 ) (23,498 ) Recoveries 103 990 1,021 2,239 4,353 Net charge-offs (7,734 ) (6,999 ) (2,884 ) (1,528 ) (19,145 ) Balance, end of year (2) $ 7,007 $ 27,281 $ 3,784 $ 3,596 $ 41,668 Period-end amount allocated to: Loans individually evaluated for impairment $ — $ 338 $ — $ — $ 338 Loans collectively evaluated for impairment 7,007 26,943 3,784 3,596 41,330 Balance, end of year (2) $ 7,007 $ 27,281 $ 3,784 $ 3,596 $ 41,668 The Company’s recorded investment in loans, excluding loans acquired, as of December 31, 2018 and 2017 related to each balance in the allowance for loan losses by portfolio segment on the basis of the Company’s impairment methodology was as follows: (In thousands) Commercial Real Estate Credit Card Other Consumer and Other Total December 31, 2018 Loans individually evaluated for impairment $ 13,062 $ 24,253 $ 296 $ 2,159 $ 39,770 Loans collectively evaluated for impairment 1,926,361 5,942,200 203,877 318,180 8,390,618 Balance, end of period $ 1,939,423 $ 5,966,453 $ 204,173 $ 320,339 $ 8,430,388 December 31, 2017 Loans individually evaluated for impairment $ 7,610 $ 31,538 $ 170 $ 4,605 $ 43,923 Loans collectively evaluated for impairment 965,909 4,208,074 185,252 302,451 5,661,686 Balance, end of period $ 973,519 $ 4,239,612 $ 185,422 $ 307,056 $ 5,705,609 Net (charge-offs)/recoveries for the years ended December 31, 2018 and 2017 , excluding loans acquired, segregated by class of loans, were as follows: (In thousands) 2018 2017 Consumer: Credit cards $ (3,046 ) $ (2,884 ) Other consumer (6,080 ) (1,528 ) Total consumer (9,126 ) (4,412 ) Real estate: Construction (1,775 ) 100 Single family residential (494 ) (1,045 ) Other commercial (2,645 ) (6,054 ) Total real estate (4,914 ) (6,999 ) Commercial: Commercial (5,878 ) (7,734 ) Agricultural — — Total commercial (5,878 ) (7,734 ) Total $ (19,918 ) $ (19,145 )

Loans Acquired (Tables)

Loans Acquired (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Schedule of Carrying Value of All Loans Acquired	At December 31, 2018 , the Company’s loan portfolio was $11.72 billion , compared to $10.78 billion at December 31, 2017 . The various categories of loans are summarized as follows: (In thousands) 2018 2017 Consumer: Credit cards $ 204,173 $ 185,422 Other consumer 201,297 280,094 Total consumer 405,470 465,516 Real estate: Construction 1,300,723 614,155 Single family residential 1,440,443 1,094,633 Other commercial 3,225,287 2,530,824 Total real estate 5,966,453 4,239,612 Commercial: Commercial 1,774,909 825,217 Agricultural 164,514 148,302 Total commercial 1,939,423 973,519 Other 119,042 26,962 Loans 8,430,388 5,705,609 Loans acquired, net of discount and allowance (1) 3,292,783 5,074,076 Total loans $ 11,723,171 $ 10,779,685 _________________________ (1) See Note 6, Loans Acquired, for segregation of loans acquired by loan class. The following table reflects the carrying value of all loans acquired as of December 31, 2018 and 2017 : Loans Acquired At December 31, (In thousands) 2018 2017 Consumer: Other consumer $ 15,658 $ 51,467 Real estate: Construction 429,605 637,032 Single family residential 566,188 793,228 Other commercial 1,848,679 2,387,777 Total real estate 2,844,472 3,818,037 Commercial: Commercial 430,914 995,587 Agricultural 1,739 66,576 Total commercial 432,653 1,062,163 Other — 142,409 Total loans acquired (1) $ 3,292,783 $ 5,074,076 _________________________ (1) Loans acquired are reported net of a $95,000 and $418,000 allowance as of December 31, 2018 and 2017 , respectively.
Schedule of Nonaccrual Loans, Excluding Loans Acquired	Nonaccrual loans, excluding loans acquired, at December 31, 2018 and 2017 , segregated by class of loans, are as follows: (In thousands) 2018 2017 Consumer: Credit cards $ 296 $ 170 Other consumer 2,159 4,605 Total consumer 2,455 4,775 Real estate: Construction 1,269 2,242 Single family residential 11,939 13,431 Other commercial 7,205 16,054 Total real estate 20,413 31,727 Commercial: Commercial 10,049 6,980 Agricultural 1,284 2,160 Total commercial 11,333 9,140 Total $ 34,201 $ 45,642 Nonaccrual loans acquired, excluding purchased credit impaired loans accounted for under ASC Topic 310-30, segregated by class of loans, are as follows (see Note 5, Loans and Allowance for Loan Losses, for discussion of nonaccrual loans): (In thousands) December 31, 2018 December 31, 2017 Consumer: Other consumer $ 140 $ 334 Real estate: Construction 114 1,767 Single family residential 6,603 12,151 Other commercial 1,167 7,401 Total real estate 7,884 21,319 Commercial: Commercial 13,578 1,748 Agricultural 38 84 Total commercial 13,616 1,832 Total $ 21,640 $ 23,485
Schedule of Aging Analysis of Past Due Loans, Excluding Loans Acquired	An age analysis of past due loans, excluding loans acquired, segregated by class of loans, is as follows: (In thousands) Gross 30-89 Days Past Due 90 Days or More Past Due Total Past Due Current Total Loans 90 Days Past Due & Accruing December 31, 2018 Consumer: Credit cards $ 1,033 $ 506 $ 1,539 $ 202,634 $ 204,173 $ 209 Other consumer 4,264 896 5,160 196,137 201,297 4 Total consumer 5,297 1,402 6,699 398,771 405,470 213 Real estate: Construction 533 308 841 1,299,882 1,300,723 — Single family residential 7,769 4,127 11,896 1,428,547 1,440,443 — Other commercial 3,379 2,773 6,152 3,219,135 3,225,287 — Total real estate 11,681 7,208 18,889 5,947,564 5,966,453 — Commercial: Commercial 4,472 5,105 9,577 1,765,332 1,774,909 11 Agricultural 467 1,055 1,522 162,992 164,514 — Total commercial 4,939 6,160 11,099 1,928,324 1,939,423 11 Other — — — 119,042 119,042 — Total $ 21,917 $ 14,770 $ 36,687 $ 8,393,701 $ 8,430,388 $ 224 December 31, 2017 Consumer: Credit cards $ 707 $ 672 $ 1,379 $ 184,043 $ 185,422 $ 332 Other consumer 5,009 3,298 8,307 271,787 280,094 10 Total consumer 5,716 3,970 9,686 455,830 465,516 342 Real estate: Construction 411 1,210 1,621 612,534 614,155 — Single family residential 8,071 6,460 14,531 1,080,102 1,094,633 1 Other commercial 2,388 8,031 10,419 2,520,405 2,530,824 — Total real estate 10,870 15,701 26,571 4,213,041 4,239,612 1 Commercial: Commercial 1,523 6,125 7,648 817,569 825,217 — Agricultural 50 2,120 2,170 146,132 148,302 — Total commercial 1,573 8,245 9,818 963,701 973,519 — Other — — — 26,962 26,962 — Total $ 18,159 $ 27,916 $ 46,075 $ 5,659,534 $ 5,705,609 $ 343 An age analysis of past due loans acquired segregated by class of loans, is as follows (see Note 5, Loans and Allowance for Loan Losses, for discussion of past due loans): (In thousands) Gross 30-89 Days Past Due 90 Days or More Past Due Total Past Due Current Total Loans 90 Days Past Due & Accruing December 31, 2018 Consumer: Other consumer $ 337 $ 49 $ 386 $ 15,272 $ 15,658 $ 2 Real estate: Construction 8,283 27 8,310 421,295 429,605 — Single family residential 4,706 3,049 7,755 558,433 566,188 — Other commercial 168 577 745 1,847,934 1,848,679 — Total real estate 13,157 3,653 16,810 2,827,662 2,844,472 — Commercial: Commercial 1,302 9,542 10,844 420,070 430,914 — Agricultural 31 5 36 1,703 1,739 — Total commercial 1,333 9,547 10,880 421,773 432,653 — Total $ 14,827 $ 13,249 $ 28,076 $ 3,264,707 $ 3,292,783 $ 2 December 31, 2017 Consumer: Other consumer $ 889 $ 260 $ 1,149 $ 50,318 $ 51,467 $ 108 Real estate: Construction 2,577 1,448 4,025 633,007 637,032 279 Single family residential 12,936 3,302 16,238 776,990 793,228 126 Other commercial 17,176 5,647 22,823 2,364,954 2,387,777 2,565 Total real estate 32,689 10,397 43,086 3,774,951 3,818,037 2,970 Commercial: Commercial 2,344 1,039 3,383 992,204 995,587 67 Agricultural 51 — 51 66,525 66,576 — Total commercial 2,395 1,039 3,434 1,058,729 1,062,163 67 Other 15 — 15 142,394 142,409 — Total $ 35,988 $ 11,696 $ 47,684 $ 5,026,392 $ 5,074,076 $ 3,145
Summary of Loans by Credit Risk Rating	The following table presents a summary of loans by credit risk rating, segregated by class of loans. (In thousands) Risk Rate 1-4 Risk Rate 5 Risk Rate 6 Risk Rate 7 Risk Rate 8 Total December 31, 2018 Consumer: Credit cards $ 203,667 $ — $ 506 $ — $ — $ 204,173 Other consumer 198,840 — 2,457 — — 201,297 Total consumer 402,507 — 2,963 — — 405,470 Real estate: Construction 1,296,988 1,910 1,825 — — 1,300,723 Single family residential 1,420,052 1,628 18,528 235 — 1,440,443 Other commercial 3,193,289 17,169 14,829 — — 3,225,287 Total real estate 5,910,329 20,707 35,182 235 — 5,966,453 Commercial: Commercial 1,742,002 8,357 24,550 — — 1,774,909 Agricultural 162,824 75 1,615 — — 164,514 Total commercial 1,904,826 8,432 26,165 — — 1,939,423 Other 119,042 — — — — 119,042 Loans acquired 3,187,083 51,255 54,097 348 — 3,292,783 Total $ 11,523,787 $ 80,394 $ 118,407 $ 583 $ — $ 11,723,171 (In thousands) Risk Rate 1-4 Risk Rate 5 Risk Rate 6 Risk Rate 7 Risk Rate 8 Total December 31, 2017 Consumer: Credit cards $ 184,920 $ — $ 502 $ — $ — $ 185,422 Other consumer 275,160 — 4,934 — — 280,094 Total consumer 460,080 — 5,436 — — 465,516 Real estate: Construction 603,126 5,795 5,218 16 — 614,155 Single family residential 1,066,902 3,954 23,490 287 — 1,094,633 Other commercial 2,480,293 19,581 30,950 — — 2,530,824 Total real estate 4,150,321 29,330 59,658 303 — 4,239,612 Commercial: Commercial 736,377 74,254 14,402 50 134 825,217 Agricultural 146,065 24 2,190 23 — 148,302 Total commercial 882,442 74,278 16,592 73 134 973,519 Other 26,962 — — — — 26,962 Loans acquired 4,918,570 62,128 93,378 — — 5,074,076 Total $ 10,438,375 $ 165,736 $ 175,064 $ 376 $ 134 $ 10,779,685 The following table presents a summary of loans acquired by credit risk rating, segregated by class of loans (see Note 5, Loans and Allowance for Loan Losses, for discussion of loan risk rating). Loans accounted for under ASC Topic 310-30 are all included in Risk Rate 1-4 in this table. (In thousands) Risk Rate 1-4 Risk Rate 5 Risk Rate 6 Risk Rate 7 Risk Rate 8 Total December 31, 2018 Consumer: Other consumer $ 15,380 $ — $ 278 $ — $ — $ 15,658 Real estate: Construction 393,122 27,621 8,862 — — 429,605 Single family residential 553,460 2,081 10,299 348 — 566,188 Other commercial 1,822,179 9,137 17,363 — — 1,848,679 Total real estate 2,768,761 38,839 36,524 348 — 2,844,472 Commercial: Commercial 401,300 12,416 17,198 — — 430,914 Agricultural 1,642 — 97 — — 1,739 Total commercial 402,942 12,416 17,295 — — 432,653 Total $ 3,187,083 $ 51,255 $ 54,097 $ 348 $ — $ 3,292,783 December 31, 2017 Consumer: Other consumer $ 50,625 $ 21 $ 821 $ — $ — $ 51,467 Real estate: Construction 604,796 30,524 1,712 — — 637,032 Single family residential 770,954 2,618 19,656 — — 793,228 Other commercial 2,337,097 15,064 35,616 — — 2,387,777 Total real estate 3,712,847 48,206 56,984 — — 3,818,037 Commercial: Commercial 946,322 13,901 35,364 — — 995,587 Agricultural 66,367 — 209 — — 66,576 Total commercial 1,012,689 13,901 35,573 — — 1,062,163 Other 142,409 — — — — 142,409 Total $ 4,918,570 $ 62,128 $ 93,378 $ — $ — $ 5,074,076
Certain Loans Acquired in Transfer	. The following is a summary of the loans acquired in the First Texas acquisition on October 19, 2017, as of the date of acquisition. (In thousands) Not Impaired Impaired Contractually required principal and interest at acquisition $ 2,246,212 $ — Non-accretable difference (expected losses and foregone interest) — — Cash flows expected to be collected at acquisition 2,246,212 — Accretable yield (37,834 ) — Basis in acquired loans at acquisition $ 2,208,378 $ — The following is a summary of the loans acquired in the OKSB acquisition on October 19, 2017, as of the date of acquisition. (In thousands) Not Impaired Impaired Contractually required principal and interest at acquisition $ 2,021,388 $ 18,136 Non-accretable difference (expected losses and foregone interest) — (6,731 ) Cash flows expected to be collected at acquisition 2,021,388 11,405 Accretable yield (36,340 ) — Basis in acquired loans at acquisition $ 1,985,048 $ 11,405 The following is a summary of the loans acquired in the Citizens acquisition on September 9, 2016, as of the date of acquisition. (In thousands) Not Impaired Impaired Contractually required principal and interest at acquisition $ 348,756 $ 1,605 Non-accretable difference (expected losses and foregone interest) — (848 ) Cash flows expected to be collected at acquisition 348,756 757 Accretable yield (8,663 ) — Basis in acquired loans at acquisition $ 340,093 $ 757 The following is a summary of the loans acquired in the Hardeman acquisition on May 15, 2017, as of the date of acquisition. (In thousands) Not Impaired Impaired Contractually required principal and interest at acquisition $ 254,189 $ 3,452 Non-accretable difference (expected losses and foregone interest) — (990 ) Cash flows expected to be collected at acquisition 254,189 2,462 Accretable yield (5,002 ) — Basis in acquired loans at acquisition $ 249,187 $ 2,462 Changes in the carrying amount of the accretable yield for all purchased impaired loans were as follows for the years ended December 31, 2018 , 2017 and 2016 . (In thousands) Accretable Yield Carrying Amount of Loans Balance, January 1, 2016 $ 954 $ 23,469 Additions 19 757 Accretable yield adjustments 5,122 — Accretion (4,440 ) 4,440 Payments and other reductions, net — (10,864 ) Balance, December 31, 2016 1,655 17,802 Additions — 13,793 Accretable yield adjustments 4,893 — Accretion (5,928 ) 5,928 Payments and other reductions, net — (20,407 ) Balance, December 31, 2017 620 17,116 Additions — — Accretable yield adjustments 2,045 — Accretion (1,205 ) 1,205 Payments and other reductions, net — (14,271 ) Balance, December 31, 2018 $ 1,460 $ 4,050

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill and Other Intangibles	The Company’s goodwill and other intangibles (carrying basis and accumulated amortization) at December 31, 2018 and 2017 were as follows: (In thousands) 2018 2017 Goodwill $ 845,687 $ 842,651 Core deposit premiums: Gross carrying amount 105,984 105,984 Accumulated amortization (26,177 ) (16,659 ) Core deposit premiums, net 79,807 89,325 Books of business intangible: Gross carrying amount 15,234 15,414 Accumulated amortization (3,707 ) (2,827 ) Books of business intangible, net 11,527 12,587 Other intangibles: Gross carrying amount 2,068 6,037 Accumulated amortization (2,068 ) (1,878 ) Other intangibles, net — 4,159 Other intangible assets, net 91,334 106,071 Total goodwill and other intangible assets $ 937,021 $ 948,722
Schedule of Estimated Remaining Amortization Expense	The Company’s estimated remaining amortization expense on intangibles as of December 31, 2018 is as follows: Year (In thousands) 2019 $ 10,565 2020 10,552 2021 10,490 2022 10,438 2023 10,156 Thereafter 39,133 Total $ 91,334

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Components of Provision for Income Taxes	The provision for income taxes for the years ended December 31 is comprised of the following components: (In thousands) 2018 2017 2016 Income taxes currently payable $ 41,946 $ 38,732 $ 36,792 Deferred income taxes 8,412 23,251 9,832 Provision for income taxes $ 50,358 $ 61,983 $ 46,624
Schedule of Deferred Income Tax Assets and Liabilities	The tax effects of temporary differences between the tax basis of assets and liabilities and their financial reporting amounts that give rise to deferred income tax assets and liabilities, and their approximate tax effects, are as follows as of December 31, 2018 and 2017 : (In thousands) 2018 2017 Deferred tax assets: Loans acquired $ 12,536 $ 19,885 Allowance for loan losses 13,947 10,773 Valuation of foreclosed assets 1,474 2,852 Tax NOLs from acquisition 7,242 7,821 Deferred compensation payable 2,707 2,433 Accrued equity and other compensation 8,182 5,302 Acquired securities 397 578 Unrealized loss on available-for-sale securities 9,196 6,107 Other 7,042 8,813 Gross deferred tax assets 62,723 64,564 Deferred tax liabilities: Goodwill and other intangible amortization (30,471 ) (32,572 ) Accumulated depreciation (13,361 ) (8,945 ) Other (5,360 ) (4,413 ) Gross deferred tax liabilities (49,192 ) (45,930 ) Net deferred tax asset, included in other assets $ 13,531 $ 18,634
Schedule of Reconciliation of Income Tax Expense	A reconciliation of income tax expense at the statutory rate to the Company’s actual income tax expense is shown below for the years ended December 31: (In thousands) 2018 2017 2016 Computed at the statutory rate (1) $ 55,875 $ 54,223 $ 50,203 Increase (decrease) in taxes resulting from: State income taxes, net of federal tax benefit 5,015 1,582 2,121 Discrete items related to ASU 2016-09 (2,439 ) (1,480 ) — Tax exempt interest income (3,168 ) (4,209 ) (4,207 ) Tax exempt earnings on BOLI (869 ) (926 ) (905 ) Federal tax credits (3,003 ) (1,586 ) (1,161 ) Impact of DTA remeasurement — 11,471 — Other differences, net (1,053 ) 2,908 573 Actual tax provision $ 50,358 $ 61,983 $ 46,624 _________________________ (1) The statutory rate was 21% for 2018 compared to 35% for 2017 and 2016.

Securities Sold Under Agreeme_2

Securities Sold Under Agreements to Repurchase (Tables)	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Schedule of Repurchase Agreements	The remaining contractual maturity of the securities sold under agreements to repurchase in the consolidated balance sheets as of December 31, 2018 and 2017 is presented in the following tables. Remaining Contractual Maturity of the Agreements (In thousands) Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total December 31, 2018 Repurchase agreements: U.S. Government agencies $ 95,542 $ — $ — $ — $ 95,542 December 31, 2017 Repurchase agreements: U.S. Government agencies $ 122,019 $ — $ — $ — $ 122,019

Other Borrowings and Subordin_2

Other Borrowings and Subordinated Debentures (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt	Debt at December 31, 2018 and 2017 consisted of the following components. (In thousands) 2018 2017 Other Borrowings FHLB advances, net of discount, due 2019 to 2033, 1.38% to 7.37% secured by residential real estate loans $ 1,345,450 $ 1,261,642 Revolving credit agreement, due 10/4/2019, floating rate of 1.50% above the one month LIBOR rate, unsecured — 75,000 Notes payable, due 10/15/2020, 3.85%, fixed rate, unsecured — 43,382 Total other borrowings 1,345,450 1,380,024 Subordinated Notes and Debentures Subordinated notes payable, due 4/1/2028, fixed-to-floating rate (fixed rate of 5.00% through 3/31/2023, floating rate of 2.15% above the three month LIBOR rate, reset quarterly) 330,000 — Trust preferred securities, due 12/30/2033, floating rate of 2.80% above the three month LIBOR rate, reset quarterly, callable without penalty — 20,620 Trust preferred securities, net of discount, due 6/30/2035, floating rate of 1.75% above the three month LIBOR rate, reset quarterly, callable without penalty — 9,327 Trust preferred securities, net of discount, due 9/15/2037, floating rate of 1.37% above the three month LIBOR rate, reset quarterly 10,310 10,284 Trust preferred securities, net of discount, due 12/5/2033, floating rate of 2.88% above the three month LIBOR rate, reset quarterly, callable without penalty — 5,156 Trust preferred securities, net of discount, due 10/18/2034, floating rate of 2.00% above the three month LIBOR rate, reset quarterly, callable without penalty — 5,148 Trust preferred securities, net of discount, due 6/6/2037, floating rate of 1.57% above the three month LIBOR rate, reset quarterly, callable without penalty 10,310 10,288 Trust preferred securities, due 12/15/2035, floating rate of 1.45% above the three month LIBOR rate, reset quarterly, callable without penalty 6,702 6,702 Trust preferred securities, due 6/26/2033, floating rate of 3.10% above the three month LIBOR rate, reset quarterly, callable without penalty — 20,619 Trust preferred securities, due 10/7/2033, floating rate of 2.85% above the three month LIBOR rate, reset quarterly, callable without penalty — 25,774 Trust preferred securities, due 9/15/2037, floating rate of 2.00% above the three month LIBOR rate, reset quarterly, callable without penalty — 8,248 Other subordinated debentures, net of discount, due 9/30/2023, floating rate equal to daily average of prime rate, reset quarterly — 18,399 Unamortized debt issuance costs (3,372 ) — Total subordinated notes and debentures 353,950 140,565 Total other borrowings and subordinated debt $ 1,699,400 $ 1,520,589
Schedule of Aggregate Annual Maturities of Long-term Debt	Aggregate annual maturities of long-term debt at December 31, 2018 , are as follows: Year (In thousands) 2019 $ 2,135 2020 2,109 2021 1,800 2022 949 2023 923 Thereafter 361,484 Total $ 369,400

Transactions With Related Par_2

Transactions With Related Parties (Tables)	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	(In thousands) 2018 2017 Balance, beginning of year $ 58,867 $ 65,834 New extensions of credit 7,661 9,092 Repayments (137 ) (16,059 ) Balance, end of year $ 66,391 $ 58,867

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Compensation Plan Transactions	The table below summarizes the transactions under the Company’s active stock compensation plans at December 31, 2018 , 2017 and 2016 , and changes during the years then ended: Stock Options Outstanding Stock Awards Outstanding Stock Units Outstanding Number of Shares (000) Weighted Average Exercise Price Number of Shares (000) Weighted Average Exercise Price Number of Shares (000) Weighted Average Exercise Price Balance, December 31, 2015 970 $ 20.31 342 $ 17.83 158 $ 21.33 Granted 116 23.51 272 23.46 286 23.48 Stock options exercised (127 ) 15.14 — — — — Stock awards/units vested — — (318 ) 20.96 (25 ) 22.77 Forfeited/expired (13 ) 17.53 (18 ) 21.85 (13 ) 23.04 Balance, December 31, 2016 946 21.43 278 20.48 406 22.70 Granted — — — — 906 28.86 Stock options exercised (122 ) 17.66 — — — — Stock awards/units vested — — (91 ) 19.40 (449 ) 27.13 Forfeited/expired (12 ) 22.67 (25 ) 21.91 (35 ) 25.76 Balance, December 31, 2017 812 21.98 162 20.85 828 26.13 Granted — — — — 429 29.16 Stock options exercised (112 ) 19.22 — — — — Stock awards/units vested — — (80 ) 20.41 (311 ) 25.56 Forfeited/expired (5 ) 21.73 (10 ) 20.12 (129 ) 27.95 Balance, December 31, 2018 695 $ 22.42 72 $ 21.45 817 $ 27.65 Exercisable, December 31, 2018 662 $ 22.37
Information about Stock Options under Plans Outstanding	The following table summarizes information about stock options under the plans outstanding at December 31, 2018 : Options Outstanding Options Exercisable Range of Exercise Prices Number of Shares (000) Weighted Average Remaining Contractual Life (Years) Weighted Average Exercise Price Number of Shares (000) Weighted Average Exercise Price $ 9.46 — $ 9.46 1 3.04 $9.46 1 $9.46 10.65 — 10.65 4 4.07 10.65 4 10.65 10.76 — 10.76 2 1.05 10.76 2 10.76 20.29 — 20.29 71 6.00 20.29 71 20.29 20.36 — 20.36 3 5.88 20.36 2 20.36 22.20 — 22.20 74 6.23 22.20 74 22.20 22.75 — 22.75 436 6.61 22.75 436 22.75 23.51 — 23.51 97 7.05 23.51 65 23.51 24.07 — 24.07 7 6.71 24.07 7 24.07 $ 9.46 — $ 24.07 695 6.53 $22.42 662 $22.37
Weighted-average Assumptions	The weighted-average assumptions used to determine the fair value of options granted for the years ended December 31, 2016 is detailed in the table below: 2016 Expected dividend yield 1.96 % Expected stock price volatility 27.34 % Risk-free interest rate 2.01 % Expected life of options (in years) 7
Restricted Performance Stock Unit Activity	The table below summarizes the Company’s restricted performance stock unit activity for the years ended December 31, 2018 , 2017 and 2016 : (In thousands) Performance Stock Units Non-vested, December 31, 2015 118 Granted 70 Vested (earned) — Forfeited (7 ) Non-vested, December 31, 2016 181 Granted 57 Vested (earned) (57 ) Forfeited (4 ) Non-vested, December 31, 2017 177 Granted 72 Vested (earned) (55 ) Forfeited (17 ) Non-vested, December 31, 2018 177

Additional Cash Flow Informat_2

Additional Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Schedule of Additional Cash Flow Information	The following is a summary of the Company’s additional cash flow information during the years ended December 31: (In thousands) 2018 2017 2016 Interest paid $ 122,801 $ 39,384 $ 22,069 Income taxes paid 25,718 35,770 39,824 Transfers of loans to foreclosed assets held for sale 16,858 6,983 4,604 Transfers of premises to foreclosed assets and other real estate owned 3,690 5,422 — Transfers of premises held for sale to foreclosed assets and other real estate owned — 3,188 652

Other Operating Expenses (Table

Other Operating Expenses (Tables)	12 Months Ended
	Dec. 31, 2018
Other Income and Expenses [Abstract]
Schedule of Other Operating Expenses	Other operating expenses consist of the following: (In thousands) 2018 2017 2016 Professional services $ 16,685 $ 19,500 $ 14,630 Postage 5,785 4,686 4,599 Telephone 5,947 4,262 4,294 Credit card expense 14,338 12,188 11,328 Marketing 8,410 11,141 6,929 Operating supplies 2,346 1,980 1,824 Amortization of intangibles 11,009 7,668 5,945 Branch right sizing expense 1,341 434 3,600 Other expense 45,714 27,020 20,364 Total other operating expenses $ 111,575 $ 88,879 $ 73,513

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	The following table sets forth the Company’s financial assets by level within the fair value hierarchy that were measured at fair value on a recurring basis as of December 31, 2018 and 2017 . Fair Value Measurements (In thousands) Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2018 Available-for-sale securities U.S. Government agencies $ 154,301 $ — $ 154,301 $ — Mortgage-backed securities 1,522,900 — 1,522,900 — States and political subdivisions 314,843 — 314,843 — Other securities 159,708 — 159,708 — Other assets held for sale 1,790 — — 1,790 Derivative asset 6,242 — 6,242 — Other liabilities held for sale (162 ) — — (162 ) Derivative liability (5,283 ) — (5,283 ) — December 31, 2017 Available-for-sale securities U.S. Government agencies $ 139,724 $ — $ 139,724 $ — Mortgage-backed securities 1,187,317 — 1,187,317 — States and political subdivisions 143,165 — 143,165 — Other securities 119,311 — 119,311 — Other assets held for sale 165,780 — — 165,780 Derivative asset 3,634 — 3,634 — Other liabilities held for sale (157,366 ) — — (157,366 ) Derivative liability (3,068 ) — (3,068 ) —
Fair Value, Assets Measured on Nonrecurring	The following table sets forth the Company’s financial assets by level within the fair value hierarchy that were measured at fair value on a nonrecurring basis as of December 31, 2018 and 2017 . Fair Value Measurements Using (In thousands) Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2018 Impaired loans (1) (2) (collateral dependent) $ 17,789 $ — $ — $ 17,789 Foreclosed assets and other real estate owned (1) 23,714 — — 23,714 December 31, 2017 Impaired loans (1) (2) (collateral dependent) $ 11,229 $ — $ — $ 11,229 Foreclosed assets and other real estate owned (1) 24,093 — — 24,093 ______________________ (1) These amounts represent the resulting carrying amounts on the Consolidated Balance Sheets for impaired collateral dependent loans and foreclosed assets and other real estate owned for which fair value re-measurements took place during the period. (2) Specific allocations of $2,738,000 and $2,195,000 were related to the impaired collateral dependent loans for which fair value re-measurements took place during the periods ended December 31, 2018 and 2017 , respectively.
Fair Value, by Balance Sheet Grouping	The estimated fair values, and related carrying amounts, of the Company’s financial instruments are as follows: Carrying Fair Value Measurements (In thousands) Amount Level 1 Level 2 Level 3 Total December 31, 2018 Financial assets: Cash and cash equivalents $ 833,458 $ 833,458 $ — $ — $ 833,458 Interest bearing balances due from banks - time 4,934 — 4,934 — 4,934 Held-to-maturity securities 289,194 — 290,830 — 290,830 Mortgage loans held for sale 26,799 — — 26,799 26,799 Interest receivable 49,938 — 49,938 — 49,938 Legacy loans, net 8,373,789 — — 8,280,690 8,280,690 Loans acquired, net 3,292,783 — — 3,256,174 3,256,174 Financial liabilities: Non-interest bearing transaction accounts 2,672,405 — 2,672,405 — 2,672,405 Interest bearing transaction accounts and savings deposits 6,830,191 — 6,830,191 — 6,830,191 Time deposits 2,896,156 — — 2,872,342 2,872,342 Federal funds purchased and securities sold under agreements to repurchase 95,792 — 95,792 — 95,792 Other borrowings 1,345,450 — 1,342,868 — 1,342,868 Subordinated notes and debentures 353,950 — 355,812 — 355,812 Interest payable 9,897 — 9,897 — 9,897 December 31, 2017 Financial assets: Cash and cash equivalents $ 598,042 $ 598,042 $ — $ — $ 598,042 Interest bearing balances due from banks - time 3,314 — 3,314 — 3,314 Held-to-maturity securities 368,058 — 373,298 — 373,298 Mortgage loans held for sale 24,038 — — 24,038 24,038 Interest receivable 43,528 — 43,528 — 43,528 Legacy loans, net 5,663,941 — — 5,646,505 5,646,505 Loans acquired, net 5,074,076 — — 5,058,455 5,058,455 Financial liabilities: Non-interest bearing transaction accounts 2,665,249 — 2,665,249 — 2,665,249 Interest bearing transaction accounts and savings deposits 6,494,896 — 6,494,896 — 6,494,896 Time deposits 1,932,730 — — 1,915,539 1,915,539 Federal funds purchased and securities sold under agreements to repurchase 122,444 — 122,444 — 122,444 Other borrowings 1,380,024 — 1,381,365 — 1,381,365 Subordinated debentures 140,565 — 136,474 — 136,474 Interest payable 4,564 — 4,564 — 4,564

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of Actual Capital Amounts and Ratios	The Company’s and the subsidiary bank’s actual capital amounts and ratios are presented in the following table. Bank SNB and Southwest Bank were merged into Simmons Bank during 2018. Actual Minimum For Capital Adequacy Purposes To Be Well Capitalized Under Prompt Corrective Action Provision (In thousands) Amount Ratio (%) Amount Ratio (%) Amount Ratio (%) December 31, 2018 Total Risk-Based Capital Ratio Simmons First National Corporation $ 1,778,938 13.3 $ 1,070,038 8.0 N/A Simmons Bank 1,532,864 11.5 1,066,340 8.0 1,332,925 10.0 Tier 1 Risk-Based Capital Ratio Simmons First National Corporation 1,361,380 10.2 800,812 6.0 N/A Simmons Bank 1,469,260 11.0 801,415 6.0 1,068,553 8.0 Common Equity Tier 1 Capital Ratio Simmons First National Corporation 1,361,380 10.2 600,609 4.5 N/A Simmons Bank 1,469,260 11.0 601,061 4.5 868,199 6.5 Tier 1 Leverage Ratio Simmons First National Corporation 1,361,380 8.8 618,809 4.0 N/A Simmons Bank 1,469,260 9.5 618,636 4.0 773,295 5.0 December 31, 2017 Total Risk-Based Capital Ratio Simmons First National Corporation $ 1,388,970 11.4 $ 974,716 8.0 N/A Simmons Bank 877,728 12.1 580,316 8.0 725,395 10.0 Bank SNB 259,077 10.9 190,148 8.0 237,685 10.0 Southwest Bank 297,164 11.0 216,119 8.0 270,149 10.0 Tier 1 Risk-Based Capital Ratio Simmons First National Corporation 1,199,457 9.8 734,361 6.0 N/A Simmons Bank 835,787 11.5 436,063 6.0 581,417 8.0 Bank SNB 255,360 10.7 143,193 6.0 190,923 8.0 Southwest Bank 294,874 10.9 162,316 6.0 216,421 8.0 Common Equity Tier 1 Capital Ratio Simmons First National Corporation 1,199,457 9.8 550,771 4.5 N/A Simmons Bank 835,787 11.5 327,047 4.5 472,401 6.5 Bank SNB 255,360 10.7 107,394 4.5 155,125 6.5 Southwest Bank 294,874 10.9 121,737 4.5 175,842 6.5 Tier 1 Leverage Ratio Simmons First National Corporation 1,199,457 9.2 521,503 4.0 N/A Simmons Bank 835,787 9.2 363,386 4.0 454,232 5.0 Bank SNB 255,360 10.1 101,133 4.0 126,416 5.0 Southwest Bank 294,874 12.2 96,680 4.0 120,850 5.0

Condensed Financial Informati_2

Condensed Financial Information (Parent Company Only) (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Condensed Balance Sheet	(In thousands) 2018 2017 ASSETS Cash and cash equivalents $ 219,063 $ 19,101 Investment securities 2,848 2,789 Investments in wholly-owned subsidiaries 2,368,870 2,288,687 Loans 774 993 Intangible assets, net 133 133 Premises and equipment 5,804 10,369 Other assets 29,974 31,181 TOTAL ASSETS $ 2,627,466 $ 2,353,253 LIABILITIES Short-term debt $ — $ 75,000 Long-term debt 353,950 183,947 Other liabilities 27,082 9,742 Total liabilities 381,032 268,689 STOCKHOLDERS’ EQUITY Common stock 923 920 Surplus 1,597,944 1,586,034 Undivided profits 674,941 514,874 Accumulated other comprehensive loss Unrealized depreciation on available-for-sale securities, net of income taxes of ($9,686) and ($6,108) at December 31, 2018 and 2017 respectively (27,374 ) (17,264 ) Total stockholders’ equity 2,246,434 2,084,564 TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY $ 2,627,466 $ 2,353,253
Condensed Income Statement	(In thousands) 2018 2017 2016 INCOME Dividends from subsidiaries $ 145,980 $ 69,107 $ 83,710 Other income 658 4,111 2,465 Income 146,638 73,218 86,175 EXPENSE 32,714 32,234 21,990 Income before income taxes and equity in undistributed net income of subsidiaries 113,924 40,984 64,185 Provision for income taxes (10,732 ) (12,311 ) (7,557 ) Income before equity in undistributed net income of subsidiaries 124,656 53,295 71,742 Equity in undistributed net income of subsidiaries 91,057 39,645 25,072 NET INCOME 215,713 92,940 96,814 Preferred stock dividends — — 24 NET INCOME AVAILABLE TO COMMON SHAREHOLDERS $ 215,713 $ 92,940 $ 96,790
Condensed Statement of Comprehensive Income	(In thousands) 2018 2017 2016 NET INCOME $ 215,713 $ 92,940 $ 96,814 OTHER COMPREHENSIVE INCOME (LOSS) Equity in other comprehensive (loss) income of subsidiaries (10,110 ) 964 (12,547 ) COMPREHENSIVE INCOME $ 205,603 $ 93,904 $ 84,267
Condensed Cash Flow Statement	(In thousands) 2018 2017 2016 CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 215,713 $ 92,940 $ 96,814 Items not requiring (providing) cash Stock-based compensation expense 9,725 10,681 3,418 Depreciation and amortization 880 1,183 700 Deferred income taxes 26 1,190 (2,526 ) Equity in undistributed net income of bank subsidiaries (91,057 ) (39,645 ) (25,072 ) Changes in Other assets 1,524 8,585 2,816 Other liabilities 17,340 (6,769 ) (1,358 ) Net cash provided by operating activities 154,151 68,165 74,792 CASH FLOWS FROM INVESTING ACTIVITIES Net originations of loans 219 90 (1,710 ) Net proceeds from (purchases of) premises and equipment 3,342 (18 ) (6,896 ) Repayment of (advances to) subsidiaries 2,667 (15,000 ) — Proceeds from maturities of available-for-sale securities 152 42 1,973 Purchases of available-for-sale securities (211 ) (2,752 ) (3 ) Cash paid in business combinations — (100,468 ) (35,048 ) Other, net (1,903 ) — — Net cash provided by (used in) investing activities 4,266 (118,106 ) (41,684 ) CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from issuance of subordinated notes 326,355 — — Issuance (repayment) of long-term debt, net (231,352 ) 8,014 (4,544 ) Issuance of common stock, net 2,188 2,878 4,938 Dividends paid on preferred stock — — (24 ) Dividends paid on common stock (55,646 ) (35,116 ) (28,743 ) Redemption of preferred stock — — (30,852 ) Net cash provided by (used in) financing activities 41,545 (24,224 ) (59,225 ) INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS 199,962 (74,165 ) (26,117 ) CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR 19,101 93,266 119,383 CASH AND CASH EQUIVALENTS, END OF YEAR $ 219,063 $ 19,101 $ 93,266

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details) $ in Millions	Nov. 13, 2018USD ($)branchshares	Feb. 08, 2018	Feb. 28, 2018	Dec. 31, 2018USD ($)financial_centersegmentshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of financial centers | financial_center				191
Number of reportable segments | segment				1
Derivative asset, notional amount				$ 561.3	$ 303.5
Stock split, conversion ratio		2	2
Scenario, Plan | Reliance Bancshares, Inc.
Business Acquisition [Line Items]
Equity interest issued or issuable (in shares) | shares	4,000,000
Payments to acquire businesses, gross	$ 62.7
Number of bank branches | branch	20
Assets acquired	$ 1,500
Loans acquired	1,100
Deposits acquired	$ 1,200
Series A Preferred Stock | Scenario, Plan | Reliance Bancshares, Inc.
Business Acquisition [Line Items]
Conversion ratio	1
Series B Preferred Stock | Scenario, Plan | Reliance Bancshares, Inc.
Business Acquisition [Line Items]
Conversion ratio	1
Series C Preferred Stock | Scenario, Plan | Reliance Bancshares, Inc.
Business Acquisition [Line Items]
Conversion ratio	1
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares) | shares				0	0	0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Net income available to common shareholders		$ 215,713	$ 92,940	$ 96,790
Average common shares outstanding (in shares)		92,268	69,385	61,291
Average potential dilutive common shares (in shares)		562	468	636
Average diluted common shares (in shares)		92,830	69,853	61,927
Basic earnings per share (in dollars per share)	[1]	$ 2.34	$ 1.34	$ 1.58
Diluted earnings per share (in dollars per share)	[1]	$ 2.32	$ 1.33	$ 1.56
[1]	Per share amounts for the years ended 2017 and 2016 have been restated to reflect the effect of the two-for-one stock split on February 8, 2018.

Acquisitions (Details)

Acquisitions (Details)	Oct. 19, 2017USD ($)branchshares	May 15, 2017USD ($)branchshares	Sep. 09, 2016USD ($)branchshares	Dec. 31, 2017USD ($)	Dec. 31, 2018USD ($)	Oct. 18, 2017USD ($)	Jun. 30, 2017USD ($)	May 14, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Sep. 08, 2016USD ($)
Business Acquisition [Line Items]
Goodwill				$ 842,651,000	$ 845,687,000
OKSB Merger
Business Acquisition [Line Items]
Equity interest issued or issuable (in shares) | shares	14,488,604
Equity interest issued or issuable, value assigned	$ 431,400,000
Payments to acquire businesses, gross	$ 94,900,000
Number of bank branches | branch	29
Assets acquired	$ 2,690,915,000					$ 2,686,489,000
Loans acquired	1,996,453,000			2,021,000,000		2,039,524,000
Deposits acquired	1,966,355,000					1,968,568,000
Goodwill	$ 229,144,000					13,545,000
Revenue of acquiree since acquisition date, actual				29,200,000
Earnings or loss of acquiree since acquisition date, actual				10,500,000
First Texas Merger
Business Acquisition [Line Items]
Equity interest issued or issuable (in shares) | shares	12,999,840
Equity interest issued or issuable, value assigned	$ 387,100,000
Payments to acquire businesses, gross	$ 70,000,000
Number of bank branches | branch	15
Assets acquired	$ 2,427,226,000					2,453,283,000
Loans acquired	2,208,378,000			2,246,000,000		2,246,212,000
Deposits acquired	1,881,658,000					1,881,941,000
Goodwill	$ 240,843,000					$ 37,227,000
Revenue of acquiree since acquisition date, actual				27,600,000
Earnings or loss of acquiree since acquisition date, actual				5,700,000
OKSB and First Texas Acquisitions
Business Acquisition [Line Items]
Acquisition related costs				$ 9,400,000
Hardeman County Investment Company, Inc.
Business Acquisition [Line Items]
Equity interest issued or issuable (in shares) | shares		1,599,940
Equity interest issued or issuable, value assigned		$ 42,600,000
Payments to acquire businesses, gross		$ 30,000,000
Number of bank branches | branch		10
Assets acquired		$ 462,924,000						$ 468,829,000
Loans acquired		251,649,000					$ 254,200,000	257,641,000
Deposits acquired		388,976,000						389,344,000
Goodwill		$ 29,371,000						$ 11,485,000
Citizens National Bank
Business Acquisition [Line Items]
Equity interest issued or issuable (in shares) | shares			1,671,482
Equity interest issued or issuable, value assigned			$ 41,300,000
Payments to acquire businesses, gross			$ 35,000,000
Number of bank branches | branch			9
Assets acquired			$ 585,149,000								$ 585,204,000
Loans acquired			340,850,000							$ 348,800,000	350,361,000
Deposits acquired			509,857,000								$ 509,857,000
Goodwill			$ 23,376,000						$ 21,500,000

Acquisitions - Assets Acquired

Acquisitions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Oct. 19, 2017	May 15, 2017	Sep. 09, 2016	Dec. 31, 2018	Dec. 31, 2017	Oct. 18, 2017	Jun. 30, 2017	May 14, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 08, 2016
Business Acquisition [Line Items]
Goodwill				$ 845,687	$ 842,651
Liabilities Assumed
Goodwill				$ 845,687	842,651
OKSB Merger
Business Acquisition [Line Items]
Cash and due from banks	$ 79,517					$ 79,517
Investment securities	484,173					485,468
Loans acquired	1,996,453				2,021,000	2,039,524
Allowance for loan losses	0					(26,957)
Foreclosed assets	5,157					6,284
Premises and equipment	26,667					21,210
Bank owned life insurance	28,704					28,704
Goodwill	229,144					13,545
Other assets	24,314					33,455
Total assets acquired	2,690,915					2,686,489
Liabilities Assumed
Non-interest bearing transaction accounts	485,971					485,971
Interest bearing transaction accounts and savings deposits	869,252					869,252
Time deposits	611,132					613,345
Total deposits	1,966,355					1,968,568
Securities sold under agreement to repurchase	11,256					11,256
Other borrowings	347,000					347,000
Subordinated debentures	46,393					46,393
Accrued interest and other liabilities	22,804					17,440
Total liabilities assumed	2,393,808					2,390,657
Total equity assumed						295,832
Total liabilities and equity assumed	2,393,808					2,686,489
Net assets acquired	297,107
Purchase price	526,251
Goodwill	229,144					13,545
OKSB Merger | Core deposit intangible
Business Acquisition [Line Items]
Intangibles	42,124					1,933
OKSB Merger | Other intangibles
Business Acquisition [Line Items]
Intangibles	3,806					3,806
OKSB Merger | Fair Value Adjustments
Business Acquisition [Line Items]
Cash and due from banks	0
Investment securities	(1,295)
Loans acquired	(43,071)
Allowance for loan losses	26,957
Foreclosed assets	(1,127)
Premises and equipment	5,457
Bank owned life insurance	0
Goodwill	(13,545)
Other assets	(9,141)
Total assets acquired	4,426
Liabilities Assumed
Non-interest bearing transaction accounts	0
Interest bearing transaction accounts and savings deposits	0
Time deposits	(2,213)
Total deposits	(2,213)
Securities sold under agreement to repurchase	0
Other borrowings	0
Subordinated debentures	0
Accrued interest and other liabilities	5,364
Total liabilities assumed	3,151
Total equity assumed	(295,832)
Total liabilities and equity assumed	(292,681)
Goodwill	(13,545)
OKSB Merger | Fair Value Adjustments | Core deposit intangible
Business Acquisition [Line Items]
Intangibles	40,191
OKSB Merger | Fair Value Adjustments | Other intangibles
Business Acquisition [Line Items]
Intangibles	0
First Texas Merger
Business Acquisition [Line Items]
Cash and due from banks	59,277					59,277
Investment securities	80,518					81,114
Loans acquired	2,208,378				$ 2,246,000	2,246,212
Allowance for loan losses	(200)					(20,864)
Premises and equipment	34,987					24,864
Bank owned life insurance	7,190					7,190
Goodwill	240,843					37,227
Other assets	29,748					18,263
Total assets acquired	2,427,226					2,453,283
Liabilities Assumed
Non-interest bearing transaction accounts	74,410					74,410
Interest bearing transaction accounts and savings deposits	1,683,298					1,683,298
Time deposits	123,950					124,233
Total deposits	1,881,658					1,881,941
Securities sold under agreement to repurchase	50,000					50,000
Other borrowings	235,000					235,000
Subordinated debentures	30,912					30,323
Accrued interest and other liabilities	13,396					11,727
Total liabilities assumed	2,210,966					2,208,991
Total equity assumed						244,292
Total liabilities and equity assumed	2,210,966					2,453,283
Net assets acquired	216,260
Purchase price	457,103
Goodwill	240,843					37,227
First Texas Merger | Core deposit intangible
Business Acquisition [Line Items]
Intangibles	7,328					$ 0
First Texas Merger | Fair Value Adjustments
Business Acquisition [Line Items]
Cash and due from banks	0
Investment securities	(596)
Loans acquired	(37,834)
Allowance for loan losses	20,664
Premises and equipment	10,123
Bank owned life insurance	0
Goodwill	(37,227)
Other assets	11,485
Total assets acquired	(26,057)
Liabilities Assumed
Non-interest bearing transaction accounts	0
Interest bearing transaction accounts and savings deposits	0
Time deposits	(283)
Total deposits	(283)
Securities sold under agreement to repurchase	0
Other borrowings	0
Subordinated debentures	589
Accrued interest and other liabilities	1,669
Total liabilities assumed	1,975
Total equity assumed	(244,292)
Total liabilities and equity assumed	(242,317)
Goodwill	(37,227)
First Texas Merger | Fair Value Adjustments | Core deposit intangible
Business Acquisition [Line Items]
Intangibles	7,328
Hardeman County Investment Company, Inc.
Business Acquisition [Line Items]
Cash and due from banks		$ 8,001						$ 8,001
Interest bearing balances due from banks - time		1,984						1,984
Investment securities		170,369						170,654
Loans acquired		251,649					$ 254,200	257,641
Allowance for loan losses								(2,382)
Foreclosed assets		631						1,083
Premises and equipment		11,163						9,905
Bank owned life insurance		7,819						7,819
Goodwill		29,371						11,485
Other assets		2,638						2,639
Total assets acquired		462,924						468,829
Liabilities Assumed
Non-interest bearing transaction accounts		76,555						76,555
Interest bearing transaction accounts and savings deposits		214,872						214,872
Time deposits		97,549						97,917
Total deposits		388,976						389,344
Securities sold under agreement to repurchase		17,163						17,163
Other borrowings		3,000						3,000
Subordinated debentures		6,702						6,702
Accrued interest and other liabilities		3,815						1,891
Total liabilities assumed	$ 6,700	419,656						418,100
Total equity assumed								50,729
Total liabilities and equity assumed		419,656						468,829
Net assets acquired		43,268
Purchase price		72,639
Goodwill		29,371						11,485
Hardeman County Investment Company, Inc. | Core deposit intangible
Business Acquisition [Line Items]
Intangibles		7,840						0
Hardeman County Investment Company, Inc. | Other intangibles
Business Acquisition [Line Items]
Intangibles		830						$ 0
Hardeman County Investment Company, Inc. | Fair Value Adjustments
Business Acquisition [Line Items]
Cash and due from banks		0
Interest bearing balances due from banks - time		0
Investment securities		(285)
Loans acquired		(5,992)
Allowance for loan losses		2,382
Foreclosed assets		(452)
Premises and equipment		1,258
Bank owned life insurance		0
Goodwill		(11,485)
Other assets		(1)
Total assets acquired		(5,905)
Liabilities Assumed
Non-interest bearing transaction accounts		0
Interest bearing transaction accounts and savings deposits		0
Time deposits		(368)
Total deposits		(368)
Securities sold under agreement to repurchase		0
Other borrowings		0
Subordinated debentures		0
Accrued interest and other liabilities		1,924
Total liabilities assumed		1,556
Total equity assumed		(50,729)
Total liabilities and equity assumed		(49,173)
Goodwill		(11,485)
Hardeman County Investment Company, Inc. | Fair Value Adjustments | Core deposit intangible
Business Acquisition [Line Items]
Intangibles		7,840
Hardeman County Investment Company, Inc. | Fair Value Adjustments | Other intangibles
Business Acquisition [Line Items]
Intangibles		$ 830
Citizens National Bank
Business Acquisition [Line Items]
Cash and due from banks			$ 131,116								$ 131,467
Federal funds sold			10,000								10,000
Investment securities			61,988								61,987
Loans acquired			340,850							$ 348,800	350,361
Allowance for loan losses			0								(4,313)
Foreclosed assets			3,442								4,960
Premises and equipment			8,085								6,746
Bank owned life insurance			6,632								6,632
Goodwill			23,376						$ 21,500
Other assets			17,370								17,364
Total assets acquired			585,149								585,204
Liabilities Assumed
Non-interest bearing transaction accounts			109,281								109,281
Interest bearing transaction accounts and savings deposits			204,912								204,912
Time deposits			195,664								195,664
Total deposits			509,857								509,857
Securities sold under agreement to repurchase			13,233								13,233
FHLB borrowings			4,047								4,000
Accrued interest and other liabilities			5,088								3,558
Total liabilities assumed			532,225								530,648
Total equity assumed			0								54,556
Total liabilities and equity assumed			532,225								585,204
Net assets acquired			52,924
Purchase price			76,300
Goodwill			23,376						$ 21,500
Citizens National Bank | Core deposit intangible
Business Acquisition [Line Items]
Intangibles			5,075								0
Citizens National Bank | Other intangibles
Business Acquisition [Line Items]
Intangibles			591								$ 0
Citizens National Bank | Fair Value Adjustments
Business Acquisition [Line Items]
Cash and due from banks			(351)
Federal funds sold			0
Investment securities			1
Loans acquired			(9,511)
Allowance for loan losses			4,313
Foreclosed assets			(1,518)
Premises and equipment			1,339
Bank owned life insurance			0
Other assets			6
Total assets acquired			(55)
Liabilities Assumed
Non-interest bearing transaction accounts			0
Interest bearing transaction accounts and savings deposits			0
Time deposits			0
Total deposits			0
Securities sold under agreement to repurchase			0
FHLB borrowings			47
Accrued interest and other liabilities			1,530
Total liabilities assumed			1,577
Total equity assumed			(54,556)
Total liabilities and equity assumed			(52,979)
Citizens National Bank | Fair Value Adjustments | Core deposit intangible
Business Acquisition [Line Items]
Intangibles			5,075
Citizens National Bank | Fair Value Adjustments | Other intangibles
Business Acquisition [Line Items]
Intangibles			$ 591

Acquisitions - Summary of Unaud

Acquisitions - Summary of Unaudited Pro Forma Information (Details) - OKSB and First Texas Acquisitions - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Revenue	$ 654,358	$ 620,461
Net income	$ 130,947	$ 136,199
Diluted earnings per share	$ 1.43	$ 1.52

Investment Securities - Summary

Investment Securities - Summary of Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Held-to-Maturity
Amortized Cost	$ 289,194	$ 368,058
Gross Unrealized Gains	3,051	5,977
Gross Unrealized (Losses)	(1,415)	(737)
Estimated Fair Value	290,830	373,298
Available-for-Sale
Amortized Cost	2,187,623	1,612,324
Gross Unrealized Gains	6,037	2,100
Gross Unrealized (Losses)	(41,908)	(24,907)
Estimated Fair Value	2,151,752	1,589,517
U.S. Government agencies
Held-to-Maturity
Amortized Cost	16,990	46,945
Gross Unrealized Gains	0	7
Gross Unrealized (Losses)	(49)	(228)
Estimated Fair Value	16,941	46,724
Available-for-Sale
Amortized Cost	157,523	141,559
Gross Unrealized Gains	518	116
Gross Unrealized (Losses)	(3,740)	(1,951)
Estimated Fair Value	154,301	139,724
Mortgage-backed securities
Held-to-Maturity
Amortized Cost	13,346	16,132
Gross Unrealized Gains	5	8
Gross Unrealized (Losses)	(412)	(287)
Estimated Fair Value	12,939	15,853
Available-for-Sale
Amortized Cost	1,552,487	1,208,017
Gross Unrealized Gains	3,097	246
Gross Unrealized (Losses)	(32,684)	(20,946)
Estimated Fair Value	1,522,900	1,187,317
State and political subdivisions
Held-to-Maturity
Amortized Cost	256,863	301,491
Gross Unrealized Gains	3,029	5,962
Gross Unrealized (Losses)	(954)	(222)
Estimated Fair Value	258,938	307,231
Available-for-Sale
Amortized Cost	320,142	144,642
Gross Unrealized Gains	171	532
Gross Unrealized (Losses)	(5,470)	(2,009)
Estimated Fair Value	314,843	143,165
Other securities
Held-to-Maturity
Amortized Cost	1,995	3,490
Gross Unrealized Gains	17	0
Gross Unrealized (Losses)	0	0
Estimated Fair Value	2,012	3,490
Available-for-Sale
Amortized Cost	157,471	118,106
Gross Unrealized Gains	2,251	1,206
Gross Unrealized (Losses)	(14)	(1)
Estimated Fair Value	$ 159,708	$ 119,311

Investment Securities (Details)

Investment Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Securities continuous unrealized loss position, fair value	$ 1,700,000,000	$ 1,400,000,000
Securities continuous unrealized loss position fair value (as percent)	70.30%	73.50%
Securities pledged as collateral	$ 1,000,000,000	$ 1,200,000,000
Available-for-sale securities, gross realized losses	65,000	2,400,000	$ 5,800,000
Available-for-sale securities, gross realized losses	$ 4,000	$ 1,300,000	$ 0
Income tax benefit related to security gains (losses) (as percent)	26.135%	39.225%	39.225%

Investment Securities - Securit

Investment Securities - Securities With Unrealized Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Held-to-Maturity
Held-to-maturity debt securities, less than 12 months, estimated fair value	$ 40,141	$ 57,731
Held-to-maturity debt securities, less than 12 months, gross unrealized losses	(210)	(251)
Held-to-maturity debt securities, 12 months or more, estimated fair value	79,014	43,611
Held-to-maturity debt securities,12 months or more, gross unrealized losses	(1,205)	(486)
Held-to-maturity debt securities, estimated fair value	119,155	101,342
Held-to-maturity debt securities, gross unrealized losses	(1,415)	(737)
Available-for-Sale
Available-for-sale debt securities, less than 12 months, estimated fair value	319,262	627,807
Available-for-sale debt securities, less than 12 months, gross unrealized losses	(2,786)	(5,639)
Available-for-sale debt securities, 12 months or more, estimated fair value	1,278,434	710,574
Available-for-sale debt securities, 12 months or more, gross unrealized losses	(39,122)	(19,268)
Available-for-sale debt securities, estimated fair value	1,597,696	1,338,381
Available-for-sale debt securities, gross unrealized losses	(41,908)	(24,907)
U.S. Government agencies
Held-to-Maturity
Held-to-maturity debt securities, less than 12 months, estimated fair value	992	11,961
Held-to-maturity debt securities, less than 12 months, gross unrealized losses	(2)	(6)
Held-to-maturity debt securities, 12 months or more, estimated fair value	15,948	32,778
Held-to-maturity debt securities,12 months or more, gross unrealized losses	(47)	(222)
Held-to-maturity debt securities, estimated fair value	16,940	44,739
Held-to-maturity debt securities, gross unrealized losses	(49)	(228)
Available-for-Sale
Available-for-sale debt securities, less than 12 months, estimated fair value	26,562	91,988
Available-for-sale debt securities, less than 12 months, gross unrealized losses	(221)	(921)
Available-for-sale debt securities, 12 months or more, estimated fair value	108,636	25,742
Available-for-sale debt securities, 12 months or more, gross unrealized losses	(3,519)	(1,030)
Available-for-sale debt securities, estimated fair value	135,198	117,730
Available-for-sale debt securities, gross unrealized losses	(3,740)	(1,951)
Mortgage-backed securities
Held-to-Maturity
Held-to-maturity debt securities, less than 12 months, estimated fair value	0	5,471
Held-to-maturity debt securities, less than 12 months, gross unrealized losses	0	(47)
Held-to-maturity debt securities, 12 months or more, estimated fair value	12,177	8,946
Held-to-maturity debt securities,12 months or more, gross unrealized losses	(412)	(240)
Held-to-maturity debt securities, estimated fair value	12,177	14,417
Held-to-maturity debt securities, gross unrealized losses	(412)	(287)
Available-for-Sale
Available-for-sale debt securities, less than 12 months, estimated fair value	163,560	510,770
Available-for-sale debt securities, less than 12 months, gross unrealized losses	(1,146)	(4,516)
Available-for-sale debt securities, 12 months or more, estimated fair value	1,037,679	609,329
Available-for-sale debt securities, 12 months or more, gross unrealized losses	(31,538)	(16,430)
Available-for-sale debt securities, estimated fair value	1,201,239	1,120,099
Available-for-sale debt securities, gross unrealized losses	(32,684)	(20,946)
State and political subdivisions
Held-to-Maturity
Held-to-maturity debt securities, less than 12 months, estimated fair value	39,149	40,299
Held-to-maturity debt securities, less than 12 months, gross unrealized losses	(208)	(198)
Held-to-maturity debt securities, 12 months or more, estimated fair value	50,889	1,887
Held-to-maturity debt securities,12 months or more, gross unrealized losses	(746)	(24)
Held-to-maturity debt securities, estimated fair value	90,038	42,186
Held-to-maturity debt securities, gross unrealized losses	(954)	(222)
Available-for-Sale
Available-for-sale debt securities, less than 12 months, estimated fair value	129,075	25,049
Available-for-sale debt securities, less than 12 months, gross unrealized losses	(1,406)	(202)
Available-for-sale debt securities, 12 months or more, estimated fair value	132,020	75,404
Available-for-sale debt securities, 12 months or more, gross unrealized losses	(4,064)	(1,807)
Available-for-sale debt securities, estimated fair value	261,095	100,453
Available-for-sale debt securities, gross unrealized losses	(5,470)	(2,009)
Other securities
Available-for-Sale
Available-for-sale debt securities, less than 12 months, estimated fair value	65	0
Available-for-sale debt securities, less than 12 months, gross unrealized losses	(13)	0
Available-for-sale debt securities, 12 months or more, estimated fair value	99	99
Available-for-sale debt securities, 12 months or more, gross unrealized losses	(1)	(1)
Available-for-sale debt securities, estimated fair value	164	99
Available-for-sale debt securities, gross unrealized losses	$ (14)	$ (1)

Investment Securities - Income

Investment Securities - Income Earned on Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest Income, Securities, Operating, by Taxable Status [Abstract]
Total	$ 57,318	$ 40,115	$ 33,479
Held-to-maturity
Interest Income, Securities, Operating, by Taxable Status [Abstract]
Taxable	2,157	2,521	3,778
Non-taxable	7,424	8,693	10,641
Available-for-sale
Interest Income, Securities, Operating, by Taxable Status [Abstract]
Taxable	40,926	25,996	17,928
Non-taxable	$ 6,811	$ 2,905	$ 1,132

Investment Securities - Maturit

Investment Securities - Maturities of Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Held-to-maturity, amortized cost, one year or less	$ 29,579
Held-to-maturity, amortized cost, after one through five years	60,564
Held-to-maturity, amortized cost, after five through ten years	88,770
Held-to-maturity, amortized cost, after ten years	96,935
Held-to-maturity, amortized cost, securities not due on a single maturity date	13,346
Amortized Cost	289,194	$ 368,058
Held-to-maturity, fair value, one year or less	29,515
Held-to-maturity, fair value, after one through five years	60,514
Held-to-maturity, fair value, after five through ten years	88,971
Held-to-maturity, fair value, after ten years	98,891
Held-to-maturity, fair value, securities not due on a single maturity date	12,939
Held-to-maturity, fair value, total	290,830	373,298
Available-for-sale, amortized cost, one year or less	120
Available-for-sale, amortized cost, after one through five years	35,518
Available-for-sale, amortized cost, after five through ten years	39,426
Available-for-sale, amortized cost, after ten years	407,815
Available-for-sale, amortized cost, securities not due on a single maturity date	1,552,487
Available-for-sale, amortized cost, other securities (no maturity)	152,257
Amortized Cost	2,187,623	1,612,324
Available-for-sale, fair value, one year or less	119
Available-for-sale, fair value, after one through five years	34,923
Available-for-sale, fair value, after five through ten years	39,360
Available-for-sale, fair value, after ten years	400,011
Available-for-sale, fair value, securities not due on a single maturity date	1,522,900
Available-for-sale, fair value, other securities (no maturity)	154,439
Available-for-sale, fair value, total	$ 2,151,752	$ 1,589,517

Other Assets and Other Liabil_2

Other Assets and Other Liabilities Held for Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Other assets held-for-sale	$ 1,790		$ 165,780
Other liabilities held-for-sale	162		$ 157,366
Heartland
Business Acquisition [Line Items]
Value of branches and loans acquired		$ 141,000
Deposits and other liabilities assumed		$ 154,600
Other assets held-for-sale	1,800
Other liabilities held-for-sale	$ 162

Loans and Allowance for Loan _3

Loans and Allowance for Loan Losses (Details)	12 Months Ended
	Dec. 31, 2018USD ($)loan	Dec. 31, 2017USD ($)loan	Dec. 31, 2016USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	$ 11,720,000,000	$ 10,780,000,000
Impaired loans	39,800,000	43,900,000
Impaired loans, related allowance	684,000	338,000
Interest income recognized	1,400,000	1,800,000	$ 1,600,000
Average recorded investment	$ 43,900,000	$ 50,800,000	$ 36,000,000
Number of modified loans | loan	8	16
Total recorded investment on modified loans	$ 3,006,000	$ 11,001,000
Financial impact on date of restructure	$ 402,000	$ 33,000
Number of previously restructured loans paid off | loan	7	13
Restructured loans paid off	$ 655,000	$ 1,200,000
Specific reserve		26,000
OREO secured by residential estate properties	25,565,000	32,118,000
Risk Ratings 6, 7 and 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Acquired loans	119,000,000	175,600,000
Impaired | Substandard, Risk Rating 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Basis in acquired loans at acquisition	4,100,000	17,100,000
Impaired | Risk Ratings 6, 7 and 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Acquired loans	50,400,000	76,300,000
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans which formal proceedings in process	3,899,000	5,057,000
Real Estate Acquired in Satisfaction of Debt | Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
OREO secured by residential estate properties	3,530,000	3,828,000
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	$ 5,966,453,000	$ 4,239,612,000
Number of modified loans | loan	4	5
Total recorded investment on modified loans	$ 552,000	$ 8,310,000
Financial impact on date of restructure	212,000	33,000
Real Estate | Real Estate Acquired in Satisfaction of Debt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total recorded investment on modified loans	$ 2,288,000	$ 0
Real Estate | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans for which payment default | loan	2	1
Charge-off of loans	$ 92,400	$ 440,000
Loans transferred to OREO	2,169,300
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	$ 1,440,443,000	$ 1,094,633,000
Number of modified loans | loan	1	1
Total recorded investment on modified loans	$ 61,000	$ 139,000
Financial impact on date of restructure	$ 0	$ 0
Number of loans for which payment default | loan	1	1
Charge-off of loans	$ 26,500

Loans and Allowance for Loan _4

Loans and Allowance for Loan Losses - Loan Portfolio by Categories (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	$ 11,720,000	$ 10,780,000
Loans acquired, net of discount and allowance	3,292,783	5,074,076
Total loans	11,723,171	10,779,685
Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	8,430,388	5,705,609
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	405,470	465,516
Consumer | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	204,173	185,422
Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	201,297	280,094
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	5,966,453	4,239,612
Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	1,300,723	614,155
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	1,440,443	1,094,633
Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	3,225,287	2,530,824
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	1,939,423	973,519
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	1,774,909	825,217
Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	164,514	148,302
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	$ 119,042	$ 26,962

Loans and Allowance for Loan _5

Loans and Allowance for Loan Losses - Nonaccrual Loans, Excluding Loans Acquired, Segregated by Class of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	$ 34,201	$ 45,642
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	2,455	4,775
Consumer | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	296	170
Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	2,159	4,605
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	20,413	31,727
Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	1,269	2,242
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	11,939	13,431
Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	7,205	16,054
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	11,333	9,140
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	10,049	6,980
Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	$ 1,284	$ 2,160

Loans and Allowance for Loan _6

Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans, Excluding Loans Acquired, Segregated by Class of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 11,723,171	$ 10,779,685
Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	36,687	46,075
Current	8,393,701	5,659,534
Total Loans	8,430,388	5,705,609
90 Days Past Due & Accruing	224	343
Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	21,917	18,159
90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	14,770	27,916
Consumer | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	6,699	9,686
Current	398,771	455,830
Total Loans	405,470	465,516
90 Days Past Due & Accruing	213	342
Consumer | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	5,297	5,716
Consumer | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,402	3,970
Consumer | Credit cards | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,539	1,379
Current	202,634	184,043
Total Loans	204,173	185,422
90 Days Past Due & Accruing	209	332
Consumer | Credit cards | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,033	707
Consumer | Credit cards | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	506	672
Consumer | Other consumer | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	5,160	8,307
Current	196,137	271,787
Total Loans	201,297	280,094
90 Days Past Due & Accruing	4	10
Consumer | Other consumer | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	4,264	5,009
Consumer | Other consumer | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	896	3,298
Real Estate | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	18,889	26,571
Current	5,947,564	4,213,041
Total Loans	5,966,453	4,239,612
90 Days Past Due & Accruing	0	1
Real Estate | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	11,681	10,870
Real Estate | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	7,208	15,701
Real Estate | Construction | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	841	1,621
Current	1,299,882	612,534
Total Loans	1,300,723	614,155
90 Days Past Due & Accruing	0	0
Real Estate | Construction | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	533	411
Real Estate | Construction | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	308	1,210
Real Estate | Single family residential | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	11,896	14,531
Current	1,428,547	1,080,102
Total Loans	1,440,443	1,094,633
90 Days Past Due & Accruing	0	1
Real Estate | Single family residential | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	7,769	8,071
Real Estate | Single family residential | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	4,127	6,460
Real Estate | Other commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	6,152	10,419
Current	3,219,135	2,520,405
Total Loans	3,225,287	2,530,824
90 Days Past Due & Accruing	0	0
Real Estate | Other commercial | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	3,379	2,388
Real Estate | Other commercial | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	2,773	8,031
Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	11,099	9,818
Current	1,928,324	963,701
Total Loans	1,939,423	973,519
90 Days Past Due & Accruing	11	0
Commercial | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	4,939	1,573
Commercial | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	6,160	8,245
Commercial | Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	9,577	7,648
Current	1,765,332	817,569
Total Loans	1,774,909	825,217
90 Days Past Due & Accruing	11	0
Commercial | Commercial | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	4,472	1,523
Commercial | Commercial | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	5,105	6,125
Commercial | Agricultural | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,522	2,170
Current	162,992	146,132
Total Loans	164,514	148,302
90 Days Past Due & Accruing	0	0
Commercial | Agricultural | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	467	50
Commercial | Agricultural | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,055	2,120
Other | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	0	0
Current	119,042	26,962
Total Loans	119,042	26,962
90 Days Past Due & Accruing	0	$ 0
Other | Gross 30-89 Days Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	0
Other | 90 Days or More Past Due | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	$ 0

Loans and Allowance for Loan _7

Loans and Allowance for Loan Losses - Impaired Loans, Net of Government Guarantees and Excluding Loans Acquired, Segregated by Class of Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Recorded Investment	$ 39,800	$ 43,900
Related Allowance	684	338
Average Investment in Impaired Loans	43,900	50,800	$ 36,000
Interest Income Recognized	1,400	1,800	$ 1,600
Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	38,071	57,334
Recorded Investment With No Allowance	28,583	30,920
Recorded Investment With Allowance	11,187	13,003
Total Recorded Investment	39,770	43,923
Related Allowance	684	338
Average Investment in Impaired Loans	43,916	50,788
Interest Income Recognized	1,400	1,780
Consumer | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	2,607	4,925
Recorded Investment With No Allowance	2,455	4,775
Recorded Investment With Allowance	0	0
Total Recorded Investment	2,455	4,775
Related Allowance	0	0
Average Investment in Impaired Loans	3,985	3,357
Interest Income Recognized	197	153
Consumer | Credit cards | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	296	170
Recorded Investment With No Allowance	296	170
Recorded Investment With Allowance	0	0
Total Recorded Investment	296	170
Related Allowance	0	0
Average Investment in Impaired Loans	266	268
Interest Income Recognized	85	47
Consumer | Other consumer | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	2,311	4,755
Recorded Investment With No Allowance	2,159	4,605
Recorded Investment With Allowance	0	0
Total Recorded Investment	2,159	4,605
Related Allowance	0	0
Average Investment in Impaired Loans	3,719	3,089
Interest Income Recognized	112	106
Real Estate | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	22,684	39,177
Recorded Investment With No Allowance	17,694	20,804
Recorded Investment With Allowance	6,559	10,734
Total Recorded Investment	24,253	31,538
Related Allowance	247	338
Average Investment in Impaired Loans	28,516	34,239
Interest Income Recognized	859	1,175
Real Estate | Construction | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	1,344	2,522
Recorded Investment With No Allowance	784	1,347
Recorded Investment With Allowance	485	895
Total Recorded Investment	1,269	2,242
Related Allowance	211	249
Average Investment in Impaired Loans	1,651	2,711
Interest Income Recognized	50	93
Real Estate | Single family residential | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	12,906	14,347
Recorded Investment With No Allowance	11,468	12,725
Recorded Investment With Allowance	616	706
Total Recorded Investment	12,084	13,431
Related Allowance	36	53
Average Investment in Impaired Loans	13,257	12,904
Interest Income Recognized	399	443
Real Estate | Other commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	8,434	22,308
Recorded Investment With No Allowance	5,442	6,732
Recorded Investment With Allowance	5,458	9,133
Total Recorded Investment	10,900	15,865
Related Allowance	0	36
Average Investment in Impaired Loans	13,608	18,624
Interest Income Recognized	410	639
Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	12,780	13,232
Recorded Investment With No Allowance	8,434	5,341
Recorded Investment With Allowance	4,628	2,269
Total Recorded Investment	13,062	7,610
Related Allowance	437	0
Average Investment in Impaired Loans	11,415	13,192
Interest Income Recognized	344	452
Commercial | Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	10,361	9,954
Recorded Investment With No Allowance	7,254	4,306
Recorded Investment With Allowance	4,628	2,269
Total Recorded Investment	11,882	6,575
Related Allowance	437	0
Average Investment in Impaired Loans	10,003	11,670
Interest Income Recognized	301	400
Commercial | Agricultural | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	2,419	3,278
Recorded Investment With No Allowance	1,180	1,035
Recorded Investment With Allowance	0	0
Total Recorded Investment	1,180	1,035
Related Allowance	0	0
Average Investment in Impaired Loans	1,412	1,522
Interest Income Recognized	$ 43	$ 52

Loans and Allowance for Loan _8

Loans and Allowance for Loan Losses - Troubled Debt Restructurings, Excluding Loans Acquired, Segregated by Class of Loans (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)loan	Dec. 31, 2017USD ($)loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	8	16
Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	33	40
Total TDR loans | $	$ 9,215	$ 12,938
Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	12	13
Total TDR loans | $	$ 6,369	$ 7,107
Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	21	27
Total TDR loans | $	$ 2,846	$ 5,831
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	4	5
Real Estate | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	23	29
Total TDR loans | $	$ 5,664	$ 9,549
Real Estate | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	8	8
Total TDR loans | $	$ 3,536	$ 4,463
Real Estate | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	15	21
Total TDR loans | $	$ 2,128	$ 5,086
Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	1	1
Real Estate | Construction | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	3	1
Total TDR loans | $	$ 485	$ 420
Real Estate | Construction | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	0	0
Total TDR loans | $	$ 0	$ 0
Real Estate | Construction | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	3	1
Total TDR loans | $	$ 485	$ 420
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	1	1
Real Estate | Single family residential | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	16	19
Total TDR loans | $	$ 846	$ 1,095
Real Estate | Single family residential | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	6	4
Total TDR loans | $	$ 230	$ 141
Real Estate | Single family residential | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	10	15
Total TDR loans | $	$ 616	$ 954
Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	2	3
Real Estate | Other commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	4	9
Total TDR loans | $	$ 4,333	$ 8,034
Real Estate | Other commercial | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	2	4
Total TDR loans | $	$ 3,306	$ 4,322
Real Estate | Other commercial | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	2	5
Total TDR loans | $	$ 1,027	$ 3,712
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	3	11
Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	10	11
Total TDR loans | $	$ 3,551	$ 3,389
Commercial | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	4	5
Total TDR loans | $	$ 2,833	$ 2,644
Commercial | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	6	6
Total TDR loans | $	$ 718	$ 745
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	3	11
Commercial | Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	10	11
Total TDR loans | $	$ 3,551	$ 3,389
Commercial | Commercial | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	4	5
Total TDR loans | $	$ 2,833	$ 2,644
Commercial | Commercial | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	6	6
Total TDR loans | $	$ 718	$ 745

Loans and Allowance for Loan _9

Loans and Allowance for Loan Losses - Loans Restructured as TDRs, Excluding Loans Acquired, Segregated by Class of Loans (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)loan	Dec. 31, 2017USD ($)loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	8	16
Balance Prior to TDR	$ 3,006	$ 11,001
Balance	2,999	10,905
Financial Impact on Date of Restructure	$ 402	$ 33
Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	33	40
Change in Maturity Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 2,999	$ 10,866
Change in Rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 0	$ 39
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	1
Balance Prior to TDR	$ 91
Balance	91
Financial Impact on Date of Restructure	0
Consumer | Change in Maturity Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	91
Consumer | Change in Rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 0
Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	1
Balance Prior to TDR	$ 91
Balance	91
Financial Impact on Date of Restructure	0
Consumer | Other consumer | Change in Maturity Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	91
Consumer | Other consumer | Change in Rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 0
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	4	5
Balance Prior to TDR	$ 552	$ 8,310
Balance	550	8,301
Financial Impact on Date of Restructure	$ 212	$ 33
Real Estate | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	23	29
Real Estate | Change in Maturity Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 550	$ 8,301
Real Estate | Change in Rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 0	$ 0
Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	1	1
Balance Prior to TDR	$ 99	$ 456
Balance	98	456
Financial Impact on Date of Restructure	$ 0	$ 0
Real Estate | Construction | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	3	1
Real Estate | Construction | Change in Maturity Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 98	$ 456
Real Estate | Construction | Change in Rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 0	$ 0
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	1	1
Balance Prior to TDR	$ 61	$ 139
Balance	62	130
Financial Impact on Date of Restructure	$ 0	$ 0
Real Estate | Single family residential | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	16	19
Real Estate | Single family residential | Change in Maturity Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 62	$ 130
Real Estate | Single family residential | Change in Rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 0	$ 0
Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	2	3
Balance Prior to TDR	$ 392	$ 7,715
Balance	390	7,715
Financial Impact on Date of Restructure	$ 212	$ 33
Real Estate | Other commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	4	9
Real Estate | Other commercial | Change in Maturity Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 390	$ 7,715
Real Estate | Other commercial | Change in Rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 0	$ 0
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	3	11
Balance Prior to TDR	$ 2,363	$ 2,691
Balance	2,358	2,604
Financial Impact on Date of Restructure	$ 190	$ 0
Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	10	11
Commercial | Change in Maturity Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 2,358	$ 2,565
Commercial | Change in Rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 0	$ 39
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	3	11
Balance Prior to TDR	$ 2,363	$ 2,691
Balance	2,358	2,604
Financial Impact on Date of Restructure	$ 190	$ 0
Commercial | Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans | loan	10	11
Commercial | Commercial | Change in Maturity Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 2,358	$ 2,565
Commercial | Commercial | Change in Rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance	$ 0	$ 39

Loans and Allowance for Loan_10

Loans and Allowance for Loan Losses - Loans by Credit Risk Rating, Segregated by Class of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 11,723,171	$ 10,779,685
Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	11,523,787	10,438,375
Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	80,394	165,736
Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	118,407	175,064
Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	583	376
Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	134
Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,430,388	5,705,609
Loans, Excluding Acquired Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	405,470	465,516
Loans, Excluding Acquired Loans | Consumer | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	402,507	460,080
Loans, Excluding Acquired Loans | Consumer | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Consumer | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,963	5,436
Loans, Excluding Acquired Loans | Consumer | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Consumer | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Consumer | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	204,173	185,422
Loans, Excluding Acquired Loans | Consumer | Credit cards | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	203,667	184,920
Loans, Excluding Acquired Loans | Consumer | Credit cards | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Consumer | Credit cards | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	506	502
Loans, Excluding Acquired Loans | Consumer | Credit cards | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Consumer | Credit cards | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	201,297	280,094
Loans, Excluding Acquired Loans | Consumer | Other consumer | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	198,840	275,160
Loans, Excluding Acquired Loans | Consumer | Other consumer | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Consumer | Other consumer | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,457	4,934
Loans, Excluding Acquired Loans | Consumer | Other consumer | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Consumer | Other consumer | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	5,966,453	4,239,612
Loans, Excluding Acquired Loans | Real Estate | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	5,910,329	4,150,321
Loans, Excluding Acquired Loans | Real Estate | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	20,707	29,330
Loans, Excluding Acquired Loans | Real Estate | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	35,182	59,658
Loans, Excluding Acquired Loans | Real Estate | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	235	303
Loans, Excluding Acquired Loans | Real Estate | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,300,723	614,155
Loans, Excluding Acquired Loans | Real Estate | Construction | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,296,988	603,126
Loans, Excluding Acquired Loans | Real Estate | Construction | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,910	5,795
Loans, Excluding Acquired Loans | Real Estate | Construction | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,825	5,218
Loans, Excluding Acquired Loans | Real Estate | Construction | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	16
Loans, Excluding Acquired Loans | Real Estate | Construction | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,440,443	1,094,633
Loans, Excluding Acquired Loans | Real Estate | Single family residential | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,420,052	1,066,902
Loans, Excluding Acquired Loans | Real Estate | Single family residential | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,628	3,954
Loans, Excluding Acquired Loans | Real Estate | Single family residential | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	18,528	23,490
Loans, Excluding Acquired Loans | Real Estate | Single family residential | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	235	287
Loans, Excluding Acquired Loans | Real Estate | Single family residential | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,225,287	2,530,824
Loans, Excluding Acquired Loans | Real Estate | Other commercial | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,193,289	2,480,293
Loans, Excluding Acquired Loans | Real Estate | Other commercial | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	17,169	19,581
Loans, Excluding Acquired Loans | Real Estate | Other commercial | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	14,829	30,950
Loans, Excluding Acquired Loans | Real Estate | Other commercial | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Real Estate | Other commercial | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,939,423	973,519
Loans, Excluding Acquired Loans | Commercial | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,904,826	882,442
Loans, Excluding Acquired Loans | Commercial | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,432	74,278
Loans, Excluding Acquired Loans | Commercial | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	26,165	16,592
Loans, Excluding Acquired Loans | Commercial | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	73
Loans, Excluding Acquired Loans | Commercial | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	134
Loans, Excluding Acquired Loans | Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,774,909	825,217
Loans, Excluding Acquired Loans | Commercial | Commercial | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,742,002	736,377
Loans, Excluding Acquired Loans | Commercial | Commercial | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,357	74,254
Loans, Excluding Acquired Loans | Commercial | Commercial | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	24,550	14,402
Loans, Excluding Acquired Loans | Commercial | Commercial | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	50
Loans, Excluding Acquired Loans | Commercial | Commercial | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	134
Loans, Excluding Acquired Loans | Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	164,514	148,302
Loans, Excluding Acquired Loans | Commercial | Agricultural | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	162,824	146,065
Loans, Excluding Acquired Loans | Commercial | Agricultural | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	75	24
Loans, Excluding Acquired Loans | Commercial | Agricultural | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,615	2,190
Loans, Excluding Acquired Loans | Commercial | Agricultural | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	23
Loans, Excluding Acquired Loans | Commercial | Agricultural | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	119,042	26,962
Loans, Excluding Acquired Loans | Other | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	119,042	26,962
Loans, Excluding Acquired Loans | Other | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Other | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Other | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans, Excluding Acquired Loans | Other | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,292,783	5,074,076
Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,187,083	4,918,570
Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	51,255	62,128
Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	54,097	93,378
Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	348	0
Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	15,658	51,467
Loans acquired | Consumer | Other consumer | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	15,380	50,625
Loans acquired | Consumer | Other consumer | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	21
Loans acquired | Consumer | Other consumer | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	278	821
Loans acquired | Consumer | Other consumer | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Consumer | Other consumer | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,844,472	3,818,037
Loans acquired | Real Estate | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,768,761	3,712,847
Loans acquired | Real Estate | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	38,839	48,206
Loans acquired | Real Estate | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	36,524	56,984
Loans acquired | Real Estate | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	348	0
Loans acquired | Real Estate | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	429,605	637,032
Loans acquired | Real Estate | Construction | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	393,122	604,796
Loans acquired | Real Estate | Construction | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	27,621	30,524
Loans acquired | Real Estate | Construction | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,862	1,712
Loans acquired | Real Estate | Construction | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Real Estate | Construction | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	566,188	793,228
Loans acquired | Real Estate | Single family residential | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	553,460	770,954
Loans acquired | Real Estate | Single family residential | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,081	2,618
Loans acquired | Real Estate | Single family residential | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	10,299	19,656
Loans acquired | Real Estate | Single family residential | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	348	0
Loans acquired | Real Estate | Single family residential | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,848,679	2,387,777
Loans acquired | Real Estate | Other commercial | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,822,179	2,337,097
Loans acquired | Real Estate | Other commercial | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	9,137	15,064
Loans acquired | Real Estate | Other commercial | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	17,363	35,616
Loans acquired | Real Estate | Other commercial | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Real Estate | Other commercial | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	432,653	1,062,163
Loans acquired | Commercial | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	402,942	1,012,689
Loans acquired | Commercial | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	12,416	13,901
Loans acquired | Commercial | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	17,295	35,573
Loans acquired | Commercial | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Commercial | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	430,914	995,587
Loans acquired | Commercial | Commercial | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	401,300	946,322
Loans acquired | Commercial | Commercial | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	12,416	13,901
Loans acquired | Commercial | Commercial | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	17,198	35,364
Loans acquired | Commercial | Commercial | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Commercial | Commercial | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,739	66,576
Loans acquired | Commercial | Agricultural | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,642	66,367
Loans acquired | Commercial | Agricultural | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Commercial | Agricultural | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	97	209
Loans acquired | Commercial | Agricultural | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Commercial | Agricultural | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Loans acquired | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 0	142,409
Loans acquired | Other | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		142,409
Loans acquired | Other | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		0
Loans acquired | Other | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		0
Loans acquired | Other | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		0
Loans acquired | Other | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 0

Loans and Allowance for Loan_11

Loans and Allowance for Loan Losses - Net (Charge-Offs)/Recoveries, Excluding Loans Acquired, Segregated by Class of Loans (Details) - Loans, Excluding Acquired Loans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	$ (19,918)	$ (19,145)	$ (14,504)
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(9,126)	(4,412)
Consumer | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(3,046)	(2,884)	(2,288)
Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(6,080)	(1,528)
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(4,914)	(6,999)	(7,166)
Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(1,775)	100
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(494)	(1,045)
Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(2,645)	(6,054)
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(5,878)	(7,734)	$ (3,591)
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(5,878)	(7,734)
Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	$ 0	$ 0

Loans and Allowance for Loan_12

Loans and Allowance for Loan Losses - Activity in the Allowance for Loan Losses, by Portfolio Segment, for the Current Year (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	$ 42,086	$ 37,240
Provision for loan losses	38,148	26,393	$ 20,065
Balance, end of period	56,694	42,086	37,240
Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	41,668	36,286	31,351
Provision for loan losses	34,849	24,527	19,439
Charge-offs	(23,216)	(23,498)	(16,643)
Recoveries	3,298	4,353	2,139
Net charge-offs	(19,918)	(19,145)	(14,504)
Balance, end of period	56,599	41,668	36,286
Loans individually evaluated for impairment	684	338
Loans collectively evaluated for impairment	55,915	41,330
Loans acquired
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	418	954
Provision for loan losses	3,299	1,866	626
Charge-offs	(3,622)	(2,400)
Balance, end of period	95	418	954
Other Consumer and Other | Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	3,596	2,951	1,951
Provision for loan losses	4,903	2,173	2,459
Charge-offs	(6,637)	(3,767)	(1,975)
Recoveries	557	2,239	516
Net charge-offs	(6,080)	(1,528)	(1,459)
Balance, end of period	2,419	3,596	2,951
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	2,419	3,596
Commercial | Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	7,007	7,739	5,985
Provision for loan losses	19,385	7,002	5,345
Charge-offs	(6,623)	(7,837)	(3,956)
Recoveries	745	103	365
Net charge-offs	(5,878)	(7,734)	(3,591)
Balance, end of period	20,514	7,007	7,739
Loans individually evaluated for impairment	437	0
Loans collectively evaluated for impairment	20,077	7,007
Real Estate | Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	27,281	21,817	19,522
Provision for loan losses	7,376	12,463	9,461
Charge-offs	(5,905)	(7,989)	(7,517)
Recoveries	991	990	351
Net charge-offs	(4,914)	(6,999)	(7,166)
Balance, end of period	29,743	27,281	21,817
Loans individually evaluated for impairment	247	338
Loans collectively evaluated for impairment	29,496	26,943
Consumer | Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Net charge-offs	(9,126)	(4,412)
Consumer | Credit Card | Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	3,784	3,779	3,893
Provision for loan losses	3,185	2,889	2,174
Charge-offs	(4,051)	(3,905)	(3,195)
Recoveries	1,005	1,021	907
Net charge-offs	(3,046)	(2,884)	(2,288)
Balance, end of period	3,923	3,784	$ 3,779
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	$ 3,923	$ 3,784

Loans and Allowance for Loan_13

Loans and Allowance for Loan Losses - Recorded Investment in Loans, Excluding Loans Acquired (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 11,723,171	$ 10,779,685
Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	39,770	43,923
Loans collectively evaluated for impairment	8,390,618	5,661,686
Total Loans	8,430,388	5,705,609
Other Consumer and Other | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	2,159	4,605
Loans collectively evaluated for impairment	318,180	302,451
Total Loans	320,339	307,056
Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	13,062	7,610
Loans collectively evaluated for impairment	1,926,361	965,909
Total Loans	1,939,423	973,519
Real Estate | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	24,253	31,538
Loans collectively evaluated for impairment	5,942,200	4,208,074
Total Loans	5,966,453	4,239,612
Consumer | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	405,470	465,516
Consumer | Credit Card | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	296	170
Loans collectively evaluated for impairment	203,877	185,252
Total Loans	$ 204,173	$ 185,422

Loans Acquired (Details)

Loans Acquired (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Oct. 19, 2017	Oct. 18, 2017	Jun. 30, 2017	May 15, 2017	May 14, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 09, 2016	Sep. 08, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 11,723,171	$ 10,779,685
Loans allowance	56,694	42,086						$ 37,240
Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,292,783	5,074,076
Loans allowance	$ 95	418						$ 954
OKSB Merger
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		1,985,000
Loans acquired		2,021,000	$ 1,996,453	$ 2,039,524
Discount		36,300
OKSB Merger | Impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		11,400
Loans acquired		18,100
Discount		6,700
First Texas Merger
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		2,208,000
Loans acquired		2,246,000	$ 2,208,378	$ 2,246,212
Discount		$ 37,800
Hardeman County Investment Company, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans					$ 249,200
Loans acquired					254,200	$ 251,649	$ 257,641
Discount					5,000
Hardeman County Investment Company, Inc. | Impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans					2,400
Loans acquired					3,400
Discount					$ 990
Citizens National Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans									$ 340,100
Loans acquired									348,800	$ 340,850	$ 350,361
Discount									8,700
Citizens National Bank | Impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans									757
Loans acquired									1,600
Discount									$ 848

Loans Acquired - Carrying Value

Loans Acquired - Carrying Value of all Acquired Impaired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 11,723,171	$ 10,779,685
Loans allowance	56,694	42,086	$ 37,240
Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,292,783	5,074,076
Loans allowance	95	418	$ 954
Loans acquired | Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	15,658	51,467
Loans acquired | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,844,472	3,818,037
Loans acquired | Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	429,605	637,032
Loans acquired | Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	566,188	793,228
Loans acquired | Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,848,679	2,387,777
Loans acquired | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	432,653	1,062,163
Loans acquired | Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	430,914	995,587
Loans acquired | Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,739	66,576
Loans acquired | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 0	$ 142,409

Loans Acquired - Nonaccrual Acq

Loans Acquired - Nonaccrual Acquired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	$ 34,201	$ 45,642
Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	21,640	23,485
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	2,455	4,775
Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	2,159	4,605
Consumer | Other consumer | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	140	334
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	20,413	31,727
Real Estate | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	7,884	21,319
Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	1,269	2,242
Real Estate | Construction | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	114	1,767
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	11,939	13,431
Real Estate | Single family residential | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	6,603	12,151
Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	7,205	16,054
Real Estate | Other commercial | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	1,167	7,401
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	11,333	9,140
Commercial | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	13,616	1,832
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	10,049	6,980
Commercial | Commercial | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	13,578	1,748
Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	1,284	2,160
Commercial | Agricultural | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	$ 38	$ 84

Loans Acquired - Age Analysis o

Loans Acquired - Age Analysis of Past Due Acquired Loans, Excluding Loans Covered by Loss Share (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	$ 11,720,000	$ 10,780,000
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	405,470	465,516
Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	201,297	280,094
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	5,966,453	4,239,612
Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	1,300,723	614,155
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	1,440,443	1,094,633
Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	3,225,287	2,530,824
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	1,939,423	973,519
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	1,774,909	825,217
Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	164,514	148,302
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross	119,042	26,962
Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	28,076	47,684
Current	3,264,707	5,026,392
Loans and leases receivable, gross	3,292,783	5,074,076
90 Days Past Due & Accruing	2	3,145
Loans acquired | Gross 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	14,827	35,988
Loans acquired | 90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	13,249	11,696
Loans acquired | Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	386	1,149
Current	15,272	50,318
Loans and leases receivable, gross	15,658	51,467
90 Days Past Due & Accruing	2	108
Loans acquired | Consumer | Other consumer | Gross 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	337	889
Loans acquired | Consumer | Other consumer | 90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	49	260
Loans acquired | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	16,810	43,086
Current	2,827,662	3,774,951
Loans and leases receivable, gross	2,844,472	3,818,037
90 Days Past Due & Accruing	0	2,970
Loans acquired | Real Estate | Gross 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	13,157	32,689
Loans acquired | Real Estate | 90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	3,653	10,397
Loans acquired | Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	8,310	4,025
Current	421,295	633,007
Loans and leases receivable, gross	429,605	637,032
90 Days Past Due & Accruing	0	279
Loans acquired | Real Estate | Construction | Gross 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	8,283	2,577
Loans acquired | Real Estate | Construction | 90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	27	1,448
Loans acquired | Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	7,755	16,238
Current	558,433	776,990
Loans and leases receivable, gross	566,188	793,228
90 Days Past Due & Accruing	0	126
Loans acquired | Real Estate | Single family residential | Gross 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	4,706	12,936
Loans acquired | Real Estate | Single family residential | 90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	3,049	3,302
Loans acquired | Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	745	22,823
Current	1,847,934	2,364,954
Loans and leases receivable, gross	1,848,679	2,387,777
90 Days Past Due & Accruing	0	2,565
Loans acquired | Real Estate | Other commercial | Gross 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	168	17,176
Loans acquired | Real Estate | Other commercial | 90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	577	5,647
Loans acquired | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	10,880	3,434
Current	421,773	1,058,729
Loans and leases receivable, gross	432,653	1,062,163
90 Days Past Due & Accruing	0	67
Loans acquired | Commercial | Gross 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,333	2,395
Loans acquired | Commercial | 90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	9,547	1,039
Loans acquired | Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	10,844	3,383
Current	420,070	992,204
Loans and leases receivable, gross	430,914	995,587
90 Days Past Due & Accruing	0	67
Loans acquired | Commercial | Commercial | Gross 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,302	2,344
Loans acquired | Commercial | Commercial | 90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	9,542	1,039
Loans acquired | Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	36	51
Current	1,703	66,525
Loans and leases receivable, gross	1,739	66,576
90 Days Past Due & Accruing	0	0
Loans acquired | Commercial | Agricultural | Gross 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	31	51
Loans acquired | Commercial | Agricultural | 90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	$ 5	0
Loans acquired | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		15
Current		142,394
Loans and leases receivable, gross		142,409
90 Days Past Due & Accruing		0
Loans acquired | Other | Gross 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		15
Loans acquired | Other | 90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		$ 0

Loans Acquired - Summary of Acq

Loans Acquired - Summary of Acquired Loans, Excluding Loans Covered by Loss Share (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 11,723,171	$ 10,779,685
Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	11,523,787	10,438,375
Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	80,394	165,736
Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	118,407	175,064
Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	583	376
Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	134
Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,292,783	5,074,076
Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,187,083	4,918,570
Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	51,255	62,128
Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	54,097	93,378
Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	348	0
Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Consumer | Other consumer | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	15,658	51,467
Consumer | Other consumer | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	15,380	50,625
Consumer | Other consumer | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	21
Consumer | Other consumer | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	278	821
Consumer | Other consumer | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Consumer | Other consumer | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Real Estate | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,844,472	3,818,037
Real Estate | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,768,761	3,712,847
Real Estate | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	38,839	48,206
Real Estate | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	36,524	56,984
Real Estate | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	348	0
Real Estate | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Real Estate | Construction | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	429,605	637,032
Real Estate | Construction | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	393,122	604,796
Real Estate | Construction | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	27,621	30,524
Real Estate | Construction | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,862	1,712
Real Estate | Construction | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Real Estate | Construction | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Real Estate | Single family residential | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	566,188	793,228
Real Estate | Single family residential | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	553,460	770,954
Real Estate | Single family residential | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,081	2,618
Real Estate | Single family residential | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	10,299	19,656
Real Estate | Single family residential | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	348	0
Real Estate | Single family residential | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Real Estate | Other commercial | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,848,679	2,387,777
Real Estate | Other commercial | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,822,179	2,337,097
Real Estate | Other commercial | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	9,137	15,064
Real Estate | Other commercial | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	17,363	35,616
Real Estate | Other commercial | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Real Estate | Other commercial | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	432,653	1,062,163
Commercial | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	402,942	1,012,689
Commercial | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	12,416	13,901
Commercial | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	17,295	35,573
Commercial | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial | Commercial | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	430,914	995,587
Commercial | Commercial | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	401,300	946,322
Commercial | Commercial | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	12,416	13,901
Commercial | Commercial | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	17,198	35,364
Commercial | Commercial | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial | Commercial | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial | Agricultural | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,739	66,576
Commercial | Agricultural | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,642	66,367
Commercial | Agricultural | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial | Agricultural | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	97	209
Commercial | Agricultural | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial | Agricultural | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Other | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 0	142,409
Other | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		142,409
Other | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		0
Other | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		0
Other | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		0
Other | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 0

Loans Acquired - Summary of the

Loans Acquired - Summary of the Non-covered Impaired Loans Acquired in Acquisitions - Loans Acquired, Not Covered By FDIC Loss Share (Details) - Loans Acquired, Not Covered By FDIC Loss Share - USD ($) $ in Thousands	Oct. 19, 2017	May 15, 2017	Sep. 09, 2016
OKSB Merger
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractually required principal and interest at acquisition	$ 2,021,388
Non-accretable difference (expected losses and foregone interest)	0
Cash flows expected to be collected at acquisition	2,021,388
Accretable yield	(36,340)
Basis in acquired loans at acquisition	1,985,048
OKSB Merger | Impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractually required principal and interest at acquisition	18,136
Non-accretable difference (expected losses and foregone interest)	(6,731)
Cash flows expected to be collected at acquisition	11,405
Accretable yield	0
Basis in acquired loans at acquisition	11,405
First Texas Merger
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractually required principal and interest at acquisition	2,246,212
Non-accretable difference (expected losses and foregone interest)	0
Cash flows expected to be collected at acquisition	2,246,212
Accretable yield	(37,834)
Basis in acquired loans at acquisition	2,208,378
First Texas Merger | Impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractually required principal and interest at acquisition	0
Non-accretable difference (expected losses and foregone interest)	0
Cash flows expected to be collected at acquisition	0
Accretable yield	0
Basis in acquired loans at acquisition	$ 0
Hardeman County Investment Company, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractually required principal and interest at acquisition		$ 254,189
Non-accretable difference (expected losses and foregone interest)		0
Cash flows expected to be collected at acquisition		254,189
Accretable yield		(5,002)
Basis in acquired loans at acquisition		249,187
Hardeman County Investment Company, Inc. | Impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractually required principal and interest at acquisition		3,452
Non-accretable difference (expected losses and foregone interest)		(990)
Cash flows expected to be collected at acquisition		2,462
Accretable yield		0
Basis in acquired loans at acquisition		$ 2,462
Citizens National Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractually required principal and interest at acquisition			$ 348,756
Non-accretable difference (expected losses and foregone interest)			0
Cash flows expected to be collected at acquisition			348,756
Accretable yield			(8,663)
Basis in acquired loans at acquisition			340,093
Citizens National Bank | Impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractually required principal and interest at acquisition			1,605
Non-accretable difference (expected losses and foregone interest)			(848)
Cash flows expected to be collected at acquisition			757
Accretable yield			0
Basis in acquired loans at acquisition			$ 757

Loans Acquired - Changes in the

Loans Acquired - Changes in the Carrying Amount of the Accretable Yield for All Purchased Impaired and Non-impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accretable Yield
Balance, accretable yield	$ 620	$ 1,655	$ 954
Additions, accretable yield	0	0	19
Accretable yield adjustments, accretable yield	2,045	4,893	5,122
Accretion, accretable yield	(1,205)	(5,928)	(4,440)
Payments and other reductions, accretable yield	0	0	0
Balance, accretable yield	1,460	620	1,655
Carrying Amount of Loans
Balance, carrying amount of loans	17,116	17,802	23,469
Additions, carrying amount of loans	0	13,793	757
Accretion, carrying amount of loans	1,205	5,928	4,440
Payments and other reductions, net, carrying amount of loans	(14,271)	(20,407)	(10,864)
Balance, carrying amount of loans	$ 4,050	$ 17,116	$ 17,802

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 19, 2017	Oct. 18, 2017	May 15, 2017	May 14, 2017	Sep. 09, 2016
Goodwill [Line Items]
Goodwill			$ 845,687	$ 842,651
Goodwill, written off related to sale of business unit		$ 4,100
Finite-lived intangible assets, period decrease	$ 3,800	$ 1,300
Amortization of intangibles			$ 11,009	7,668	$ 5,945
Minimum
Goodwill [Line Items]
Finite-lived intangible asset, useful life			10 years
Maximum
Goodwill [Line Items]
Finite-lived intangible asset, useful life			15 years
Core deposit intangible
Goodwill [Line Items]
Amortization of intangibles			$ 9,500	6,000	4,400
Core deposit intangible | Minimum
Goodwill [Line Items]
Finite-lived intangible asset, useful life			10 years
Core deposit intangible | Maximum
Goodwill [Line Items]
Finite-lived intangible asset, useful life			15 years
Purchased Credit Card Relationships
Goodwill [Line Items]
Amortization of intangibles				310	414
Books of Business Intangible
Goodwill [Line Items]
Amortization of intangibles			$ 1,100	1,400	1,400
OKSB Merger
Goodwill [Line Items]
Goodwill						$ 229,144	$ 13,545
Finite-lived intangible assets acquired				3,800
OKSB Merger | Core deposit intangible
Goodwill [Line Items]
Finite-lived intangible assets acquired				42,100
First Texas BHC, Inc.
Goodwill [Line Items]
Goodwill						$ 240,800
First Texas BHC, Inc. | Core deposit intangible
Goodwill [Line Items]
Finite-lived intangible assets acquired				7,300
Hardeman County Investment Company, Inc.
Goodwill [Line Items]
Goodwill								$ 29,371	$ 11,485
Finite-lived intangible assets acquired				830
Hardeman County Investment Company, Inc. | Core deposit intangible
Goodwill [Line Items]
Finite-lived intangible assets acquired				$ 7,800
Citizens National Bank
Goodwill [Line Items]
Goodwill					21,500					$ 23,376
Finite-lived intangible assets acquired					591
Citizens National Bank | Core deposit intangible
Goodwill [Line Items]
Finite-lived intangible assets acquired					$ 5,100

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Goodwill and Other Intangibles (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 845,687	$ 842,651
Total	91,334	106,071
Total goodwill and other intangible assets	937,021	948,722
Core deposit intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	105,984	105,984
Accumulated amortization	(26,177)	(16,659)
Total	79,807	89,325
Books of Business Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	15,234	15,414
Accumulated amortization	(3,707)	(2,827)
Total	11,527	12,587
Other intangibles
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	2,068	6,037
Accumulated amortization	(2,068)	(1,878)
Total	$ 0	$ 4,159

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
2,019	$ 10,565
2,020	10,552
2,021	10,490
2,022	10,438
2,023	10,156
Thereafter	39,133
Total	$ 91,334	$ 106,071

Time Deposits (Details)

Time Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Time deposits, $100,000 or more	$ 1,443,000	$ 736,000
Time deposits, at or above FDIC insurance limit	753,200	396,800
Interest-bearing domestic deposit, brokered	1,386,000	$ 442,000
Time deposit maturities, next twelve months	2,384,000
Time deposit maturities, year two	407,920
Time deposit maturities, year three	83,740
Time deposit maturities, year four	13,470
Time deposit maturities, year five	6,940
Time deposit maturities, thereafter	$ 85

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income taxes currently payable	$ 41,946	$ 38,732	$ 36,792
Deferred income taxes	8,412	23,251	9,832
Provision for income taxes	$ 50,358	$ 61,983	$ 46,624

Income Taxes - Tax Effects of T

Income Taxes - Tax Effects of Temporary Differences Related to Deferred Taxes Included in Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Loans acquired	$ 12,536	$ 19,885
Allowance for loan losses	13,947	10,773
Valuation of foreclosed assets	1,474	2,852
Tax NOLs from acquisition	7,242	7,821
Deferred compensation payable	2,707	2,433
Accrued equity and other compensation	8,182	5,302
Acquired securities	397	578
Unrealized loss on available-for-sale securities	9,196	6,107
Other	7,042	8,813
Gross deferred tax assets	62,723	64,564
Deferred tax liabilities:
Goodwill and other intangible amortization	(30,471)	(32,572)
Accumulated depreciation	(13,361)	(8,945)
Other	(5,360)	(4,413)
Gross deferred tax liabilities	(49,192)	(45,930)
Net deferred tax asset, included in other assets	$ 13,531	$ 18,634

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Computed at the statutory rate	$ 55,875	$ 54,223	$ 50,203
State income taxes, net of federal tax benefit	5,015	1,582	2,121
Discrete items related to ASU 2016-09	(2,439)	(1,480)	0
Tax exempt interest income	(3,168)	(4,209)	(4,207)
Tax exempt earnings on BOLI	(869)	(926)	(905)
Federal tax credits	(3,003)	(1,586)	(1,161)
Impact of DTA remeasurement	0	11,471	0
Other differences, net	(1,053)	2,908	573
Provision for income taxes	$ 50,358	$ 61,983	$ 46,624

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Income tax expense (benefit), continuing operations, adjustment of deferred tax (asset) liability			$ 11,500
Stockholders' equity, effects of tax law changes			0
Earliest Tax Year | Federal
Income Taxes [Line Items]
Open tax year		2,015
Earliest Tax Year | State
Income Taxes [Line Items]
Open tax year		2,015
Metropolitan
Income Taxes [Line Items]
Operating loss carryforwards		$ 33,800
Retained Earnings
Income Taxes [Line Items]
Stockholders' equity, effects of tax law changes			3,016
Retained Earnings | New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2018-02
Income Taxes [Line Items]
Stockholders' equity, effects of tax law changes	$ 3,000
AOCI
Income Taxes [Line Items]
Stockholders' equity, effects of tax law changes			$ (3,016)
AOCI | New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2018-02
Income Taxes [Line Items]
Stockholders' equity, effects of tax law changes	$ (3,000)

Securities Sold Under Agreeme_3

Securities Sold Under Agreements to Repurchase (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Financial assets sold under agreements to repurchase	$ 95.5	$ 122

Securities Sold Under Agreeme_4

Securities Sold Under Agreements to Repurchase - Contractual Maturity of the Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	$ 95,500	$ 122,000
U.S. Government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	95,542	122,019
Overnight and Continuous | U.S. Government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	95,542	122,019
Up to 30 Days | U.S. Government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	0	0
30-90 Days | U.S. Government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	0	0
Greater than 90 Days | U.S. Government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	$ 0	$ 0

Other Borrowings and Subordin_3

Other Borrowings and Subordinated Debentures - Long-term Debt (Details) - USD ($)	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total other borrowings and subordinated debt	$ 1,699,400,000		$ 1,520,589,000
Revolving Credit Facility | U.S. Bank National Association
Debt Instrument [Line Items]
Total other borrowings and subordinated debt	0	$ 0	75,000,000
Total other borrowings
Debt Instrument [Line Items]
Total other borrowings and subordinated debt	1,345,450,000		1,380,024,000
FHLB advances, net of discount, due 2019 to 2033, 1.38% to 7.37% secured by residential real estate loans
Debt Instrument [Line Items]
Total other borrowings and subordinated debt	1,345,450,000		1,261,642,000
Notes payable, due 10/15/2020, 3.85%, fixed rate, unsecured
Debt Instrument [Line Items]
Total other borrowings and subordinated debt	0		43,382,000
Total subordinated notes and debentures
Debt Instrument [Line Items]
Unamortized debt issuance costs	(3,372,000)		0
Total other borrowings and subordinated debt	353,950,000		140,565,000
Subordinated Debt | Subordinated notes payable, due 4/1/2028, fixed-to-floating rate (fixed rate of 5.00% through 3/31/2023, floating rate of 2.15% above the three month LIBOR rate, reset quarterly)
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	330,000,000		0
Subordinated Debt | Trust preferred securities, due 12/30/2033, floating rate of 2.80% above the three month LIBOR rate, reset quarterly, callable without penalty
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	0		20,620,000
Subordinated Debt | Trust preferred securities, net of discount, due 6/30/2035, floating rate of 1.75% above the three month LIBOR rate, reset quarterly, callable without penalty
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	0		9,327,000
Subordinated Debt | Trust preferred securities, net of discount, due 9/15/2037, floating rate of 1.37% above the three month LIBOR rate, reset quarterly
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	10,310,000		10,284,000
Subordinated Debt | Trust preferred securities, net of discount, due 12/5/2033, floating rate of 2.88% above the three month LIBOR rate, reset quarterly, callable without penalty
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	0		5,156,000
Subordinated Debt | Trust preferred securities, net of discount, due 10/18/2034, floating rate of 2.00% above the three month LIBOR rate, reset quarterly, callable without penalty
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	0		5,148,000
Subordinated Debt | Trust preferred securities, net of discount, due 6/6/2037, floating rate of 1.57% above the three month LIBOR rate, reset quarterly, callable without penalty
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	10,310,000		10,288,000
Subordinated Debt | Trust preferred securities, due 12/15/2035, floating rate of 1.45% above the three month LIBOR rate, reset quarterly, callable without penalty
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	6,702,000		6,702,000
Subordinated Debt | Trust preferred securities, due 6/26/2033, floating rate of 3.10% above the three month LIBOR rate, reset quarterly, callable without penalty
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	0		20,619,000
Subordinated Debt | Trust preferred securities, due 10/7/2033, floating rate of 2.85% above the three month LIBOR rate, reset quarterly, callable without penalty
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	0		25,774,000
Subordinated Debt | Trust preferred securities, due 9/15/2037, floating rate of 2.00% above the three month LIBOR rate, reset quarterly, callable without penalty
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	0		8,248,000
Unsecured Debt | Other subordinated debentures, net of discount, due 9/30/2023, floating rate equal to daily average of prime rate, reset quarterly
Debt Instrument [Line Items]
Total other borrowings and subordinated debt, gross	$ 0		$ 18,399,000

Other Borrowings and Subordin_4

Other Borrowings and Subordinated Debentures - Long-term Debt 2 (Details)	12 Months Ended
	Dec. 31, 2018	Mar. 31, 2018
U.S. Bank National Association | Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.50%
FHLB advances, net of discount, due 2019 to 2033, 1.38% to 7.37% secured by residential real estate loans | Minimum
Debt Instrument [Line Items]
Debt instrument, interest rate (as percent)	1.38%
FHLB advances, net of discount, due 2019 to 2033, 1.38% to 7.37% secured by residential real estate loans | Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate (as percent)	7.37%
Notes payable, due 10/15/2020, 3.85%, fixed rate, unsecured
Debt Instrument [Line Items]
Debt instrument, interest rate (as percent)	3.85%
Subordinated Debt
Debt Instrument [Line Items]
Debt instrument, interest rate (as percent)	5.00%	5.00%
Subordinated Debt | Subordinated notes payable, due 4/1/2028, fixed-to-floating rate (fixed rate of 5.00% through 3/31/2023, floating rate of 2.15% above the three month LIBOR rate, reset quarterly) | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.15%
Subordinated Debt | Trust preferred securities, due 12/30/2033, floating rate of 2.80% above the three month LIBOR rate, reset quarterly, callable without penalty | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.80%
Subordinated Debt | Trust preferred securities, net of discount, due 6/30/2035, floating rate of 1.75% above the three month LIBOR rate, reset quarterly, callable without penalty | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.75%
Subordinated Debt | Trust preferred securities, net of discount, due 9/15/2037, floating rate of 1.37% above the three month LIBOR rate, reset quarterly | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.37%
Subordinated Debt | Trust preferred securities, net of discount, due 12/5/2033, floating rate of 2.88% above the three month LIBOR rate, reset quarterly, callable without penalty | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.88%
Subordinated Debt | Trust preferred securities, net of discount, due 10/18/2034, floating rate of 2.00% above the three month LIBOR rate, reset quarterly, callable without penalty | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.00%
Subordinated Debt | Trust preferred securities, net of discount, due 6/6/2037, floating rate of 1.57% above the three month LIBOR rate, reset quarterly, callable without penalty | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.57%
Subordinated Debt | Trust preferred securities, due 12/15/2035, floating rate of 1.45% above the three month LIBOR rate, reset quarterly, callable without penalty | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.45%
Subordinated Debt | Trust preferred securities, due 6/26/2033, floating rate of 3.10% above the three month LIBOR rate, reset quarterly, callable without penalty | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	3.10%
Subordinated Debt | Trust preferred securities, due 10/7/2033, floating rate of 2.85% above the three month LIBOR rate, reset quarterly, callable without penalty | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.85%
Subordinated Debt | Trust preferred securities, due 9/15/2037, floating rate of 2.00% above the three month LIBOR rate, reset quarterly, callable without penalty | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.00%

Other Borrowings and Subordin_5

Other Borrowings and Subordinated Debentures (Details) - USD ($)	1 Months Ended			12 Months Ended
	Oct. 31, 2018	Sep. 30, 2018	Oct. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018	Oct. 19, 2017	May 15, 2017	May 14, 2017
Debt Instrument [Line Items]
Commitment fee on unused portion of credit facility (as percent)			0.25%
Balance due				$ 1,699,400,000	$ 1,520,589,000
Repayments of subordinated debentures				113,990,000	3,000,000	$ 594,000
FHLB advances outstanding				1,300,000,000
Advances from Federal Home Loan Banks				1,300,000,000
Additional advances from Federal Home Loan Bank				1,800,000,000
Mortgage loans and investment securities securing FHLB advances				4,600,000,000
Assets				16,543,337,000	15,055,806,000
Federal Home Loan Bank Owns the Options (FOTO) Advances
Debt Instrument [Line Items]
FHLB advances outstanding				$ 675,000,000
Federal Home Loan Bank Owns the Options (FOTO) Advances | Minimum
Debt Instrument [Line Items]
Term of debt instrument				10 years
Federal Home Loan Bank Owns the Options (FOTO) Advances | Maximum
Debt Instrument [Line Items]
Term of debt instrument				15 years
OKSB and First Texas Acquisitions
Debt Instrument [Line Items]
Subordinated debt assumed								$ 77,300,000
Hardeman County Investment Company, Inc.
Debt Instrument [Line Items]
Subordinated debt assumed								$ 6,700,000	$ 419,656,000	$ 418,100,000
First Texas BHC, Inc.
Debt Instrument [Line Items]
Repayments of subordinated debentures		$ 19,100,000
U.S. Bank National Association | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity	$ 50,000,000		$ 75,000,000
Commitment fee on unused portion of credit facility (as percent)	0.30%
Balance due		$ 0		$ 0	$ 75,000,000
Subordinated Debt
Debt Instrument [Line Items]
Face amount of debt							$ 330,000,000
Debt instrument, interest rate				5.00%			5.00%
Debt issuance costs							$ 3,600,000

Other Borrowings and Subordin_6

Other Borrowings and Subordinated Debentures - Aggregate Annual Maturities of Long-term Debt (Details) $ in Thousands	Dec. 31, 2018USD ($)
Debt Disclosure [Abstract]
2,019	$ 2,135
2,020	2,109
2,021	1,800
2,022	949
2,023	923
Thereafter	361,484
Total	$ 369,400

Capital Stock (Details

Capital Stock (Details	Feb. 08, 2018	Feb. 27, 2015shares	Jul. 23, 2012shares	Feb. 28, 2018	Dec. 31, 2016	Feb. 18, 2016	Dec. 31, 2018shares	Apr. 19, 2018shares	Apr. 18, 2018shares	Dec. 31, 2017shares	Feb. 27, 2009USD ($)$ / sharesshares
Subsidiary or Equity Method Investee [Line Items]
Preferred stock, shares authorized (in shares)											40,040,000
Preferred stock, par or stated value per share (in dollars per share) | $ / shares											$ 0.01
Stock split, conversion ratio	2			2
Common stock, shares authorized (in shares)							175,000,000	175,000,000	120,000,000	120,000,000
Dividend rate (as percent)					9.00%	1.00%
Stock repurchase program, number of shares authorized to be repurchased (in shares)			1,700,000
Shares outstanding (as percent)			2.00%
Number of additional shares that can be repurchased (in shares)			308,272
Community First Bancshares Inc. | Preferred Stock
Subsidiary or Equity Method Investee [Line Items]
Equity interest issued or issuable (in shares)		30,852
Maximum
Subsidiary or Equity Method Investee [Line Items]
Preferred stock, liquidation preference, value | $											$ 80,000,000

Transactions With Related Par_3

Transactions With Related Parties (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transactions [Abstract]
Notes receivable, related parties	$ 66,391	$ 58,867	$ 65,834

Transactions With Related Par_4

Transactions With Related Parties - Related Party Transactions, Extensions of Credit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Notes Receivable, Related Parties rollforward [Roll Forward]
Balance, beginning of year	$ 58,867	$ 65,834
New extensions of credit	7,661	9,092
Repayments	(137)	(16,059)
Balance, end of year	$ 66,391	$ 58,867

Employee Benefit Plans (Details

Employee Benefit Plans (Details)	Feb. 08, 2018	Feb. 28, 2018	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)$ / sharesshares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee stock ownership plan, contribution expense			$ 10,769,000	$ 6,343,000	$ 5,488,000
Deferred compensation expense			$ 2,309,000	1,596,000	1,056,000
Defined Contribution Plan Disclosure [Line Items]
Purchase price of common stock (as percent)			95.00%
Stock split, conversion ratio	2	2
Allocated stock-based compensation expense			$ 11,227,000	$ 11,763,000	$ 5,451,000
Compensation not yet recognized, stock options			0
Compensation not yet recognized, share-based awards other than options			$ 14,714,000
Compensation cost not yet recognized, period for recognition			1 year 8 months 12 days
Options outstanding, intrinsic value			$ 1,187,000
Options exercisable, intrinsic value			$ 1,165,000
Share price (in dollars per share) | $ / shares			$ 24.13
Options, exercises in period | shares			111,728	122,012	127,424
Options, exercises in period, intrinsic value			$ 561,000	$ 1,329,000	$ 2,031,000
Options, grants in period, gross | shares			0	0	116,000
Options, grants in period, weighted average grant date fair value (in dollars per share) | $ / shares					$ 5.82
Employee Stock Purchase Plan 2015
Defined Contribution Plan Disclosure [Line Items]
Maximum annual contributions per employee, amount			$ 25,000
Service period			6 months
Special Employee Stock Purchase Plan 2015
Defined Contribution Plan Disclosure [Line Items]
Maximum annual contributions per employee, amount			$ 10,000
Purchase price of common stock (as percent)			85.00%

Employee Benefit Plans - Stock

Employee Benefit Plans - Stock Compensation Plans (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Stock options outstanding number of shares, balance (in shares)	812,000	946,000	970,000
Stock options outstanding number of shares, granted (in shares)	0	0	116,000
Stock options outstanding number of shares, stock options exercised (in shares)	(111,728)	(122,012)	(127,424)
Stock options outstanding number of shares, forfeited/expired (in shares)	(5,000)	(12,000)	(13,000)
Stock options outstanding number of shares, balance (in shares)	695,000	812,000	946,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Stock options outstanding weighted average exercise price, balance (in dollars per share)	$ 21.98	$ 21.43	$ 20.31
Stock options outstanding weighted average exercise price, granted (in dollars per share)	0	0	23.51
Stock options outstanding weighted average exercise price, exercised (in dollars per share)	19.22	17.66	15.14
Stock options outstanding weighted average exercise price, forfeited/expired (in dollars per share)	21.73	22.67	17.53
Stock options outstanding weighted average exercise price, balance (in dollars per share)	$ 22.42	$ 21.98	$ 21.43
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Stock options outstanding number of shares, exercisable (in shares)	662,000
Stock options outstanding weighted average exercise price, exercisable (in dollars per share)	$ 22.37
Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Stock awards/units outstanding number of shares, balance (in shares)	162,000	278,000	342,000
Stock awards/units outstanding number of shares, granted (in shares)	0	0	272,000
Stock options outstanding number of shares, stock awards/units vested (in shares)	(80,000)	(91,000)	(318,000)
Stock awards/units outstanding number of shares, forfeited/expired (in shares)	(10,000)	(25,000)	(18,000)
Stock awards/units outstanding number of shares, balance (in shares)	72,000	162,000	278,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Stock awards/units outstanding weighted average grant-date fair-value, balance (in dollars per share)	$ 21.45	$ 20.85	$ 20.48
Stock awards/units outstanding weighted average grant-date fair-value, granted (in dollars per share)	0	0	23.46
Stock awards/units outstanding weighted average grant-date fair-value, vested (in dollars per share)	20.41	19.40	20.96
Stock awards/units outstanding weighted average grant-date fair-value, forfeited/expired (in dollars per share)	20.12	21.91	21.85
Stock awards/units outstanding weighted average grant-date fair-value, balance (in dollars per share)	$ 20.85	$ 20.48	$ 17.83
Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Stock awards/units outstanding number of shares, balance (in shares)	828,000	406,000	158,000
Stock awards/units outstanding number of shares, granted (in shares)	429,000	906,000	286,000
Stock options outstanding number of shares, stock awards/units vested (in shares)	(311,000)	(449,000)	(25,000)
Stock awards/units outstanding number of shares, forfeited/expired (in shares)	(129,000)	(35,000)	(13,000)
Stock awards/units outstanding number of shares, balance (in shares)	817,000	828,000	406,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Stock awards/units outstanding weighted average grant-date fair-value, balance (in dollars per share)	$ 27.65	$ 26.13	$ 22.70
Stock awards/units outstanding weighted average grant-date fair-value, granted (in dollars per share)	29.16	28.86	23.48
Stock awards/units outstanding weighted average grant-date fair-value, vested (in dollars per share)	25.56	27.13	22.77
Stock awards/units outstanding weighted average grant-date fair-value, forfeited/expired (in dollars per share)	27.95	25.76	23.04
Stock awards/units outstanding weighted average grant-date fair-value, balance (in dollars per share)	$ 26.13	$ 22.70	$ 21.33
Restricted Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Stock awards/units outstanding number of shares, balance (in shares)	177,000	181,000	118,000
Stock awards/units outstanding number of shares, granted (in shares)	72,000	57,000	70,000
Stock options outstanding number of shares, stock awards/units vested (in shares)	(55,000)	(57,000)	0
Stock awards/units outstanding number of shares, forfeited/expired (in shares)	(17,000)	(4,000)	(7,000)
Stock awards/units outstanding number of shares, balance (in shares)	177,000	177,000	181,000

Employee Benefit Plans - Stoc_2

Employee Benefit Plans - Stock Options Outstanding by Range of Exercise Prices (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Defined Contribution Plan Disclosure [Line Items]
Exercise price range, lower range limit (in dollars per share)	$ 9.46
Exercise price range, upper range limit (in dollars per share)	$ 24.07
Number of outstanding options (in shares) | shares	695
Outstanding options, weighted average remaining contractual term	6 years 6 months 11 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 22.42
Number of exercisable options (in shares) | shares	662
Exercisable options, weighted average exercise price (in dollars per share)	$ 22.37
Range 1
Defined Contribution Plan Disclosure [Line Items]
Number of outstanding options (in shares) | shares	1
Outstanding options, weighted average remaining contractual term	3 years 15 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 9.46
Number of exercisable options (in shares) | shares	1
Exercisable options, weighted average exercise price (in dollars per share)	$ 9.46
Range 2
Defined Contribution Plan Disclosure [Line Items]
Exercise price range, lower range limit (in dollars per share)	9.46
Exercise price range, upper range limit (in dollars per share)	$ 9.46
Number of outstanding options (in shares) | shares	4
Outstanding options, weighted average remaining contractual term	4 years 26 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 10.65
Number of exercisable options (in shares) | shares	4
Exercisable options, weighted average exercise price (in dollars per share)	$ 10.65
Range 3
Defined Contribution Plan Disclosure [Line Items]
Exercise price range, lower range limit (in dollars per share)	10.65
Exercise price range, upper range limit (in dollars per share)	$ 10.65
Number of outstanding options (in shares) | shares	2
Outstanding options, weighted average remaining contractual term	1 year 18 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 10.76
Number of exercisable options (in shares) | shares	2
Exercisable options, weighted average exercise price (in dollars per share)	$ 10.76
Range 4
Defined Contribution Plan Disclosure [Line Items]
Exercise price range, lower range limit (in dollars per share)	10.76
Exercise price range, upper range limit (in dollars per share)	$ 10.76
Number of outstanding options (in shares) | shares	71
Outstanding options, weighted average remaining contractual term	6 years
Outstanding options, weighted average exercise price (in dollars per share)	$ 20.29
Number of exercisable options (in shares) | shares	71
Exercisable options, weighted average exercise price (in dollars per share)	$ 20.29
Range 5
Defined Contribution Plan Disclosure [Line Items]
Exercise price range, lower range limit (in dollars per share)	20.29
Exercise price range, upper range limit (in dollars per share)	20.29
Range 6
Defined Contribution Plan Disclosure [Line Items]
Exercise price range, lower range limit (in dollars per share)	20.36
Exercise price range, upper range limit (in dollars per share)	$ 20.36
Number of outstanding options (in shares) | shares	3
Outstanding options, weighted average remaining contractual term	5 years 10 months 17 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 20.36
Number of exercisable options (in shares) | shares	2
Exercisable options, weighted average exercise price (in dollars per share)	$ 20.36
Range 7
Defined Contribution Plan Disclosure [Line Items]
Exercise price range, lower range limit (in dollars per share)	22.20
Exercise price range, upper range limit (in dollars per share)	$ 22.20
Number of outstanding options (in shares) | shares	74
Outstanding options, weighted average remaining contractual term	6 years 2 months 23 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 22.20
Number of exercisable options (in shares) | shares	74
Exercisable options, weighted average exercise price (in dollars per share)	$ 22.20
Range 8
Defined Contribution Plan Disclosure [Line Items]
Exercise price range, lower range limit (in dollars per share)	22.75
Exercise price range, upper range limit (in dollars per share)	$ 22.75
Number of outstanding options (in shares) | shares	436
Outstanding options, weighted average remaining contractual term	6 years 7 months 10 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 22.75
Number of exercisable options (in shares) | shares	436
Exercisable options, weighted average exercise price (in dollars per share)	$ 22.75
Range 9
Defined Contribution Plan Disclosure [Line Items]
Exercise price range, lower range limit (in dollars per share)	23.51
Exercise price range, upper range limit (in dollars per share)	$ 23.51
Number of outstanding options (in shares) | shares	97
Outstanding options, weighted average remaining contractual term	7 years 18 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 23.51
Number of exercisable options (in shares) | shares	65
Exercisable options, weighted average exercise price (in dollars per share)	$ 23.51
Range 10
Defined Contribution Plan Disclosure [Line Items]
Exercise price range, lower range limit (in dollars per share)	24.07
Exercise price range, upper range limit (in dollars per share)	$ 24.07
Number of outstanding options (in shares) | shares	7
Outstanding options, weighted average remaining contractual term	6 years 8 months 16 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 24.07
Number of exercisable options (in shares) | shares	7
Exercisable options, weighted average exercise price (in dollars per share)	$ 24.07

Employee Benefit Plans - Weight

Employee Benefit Plans - Weighted-Average Fair Value Assumptions (Details)	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected dividend yield	1.96%
Expected stock price volatility	27.34%
Risk-free interest rate	2.01%
Expected life of options (in years)	7 years

Additional Cash Flow Informat_3

Additional Cash Flow Information - Additional Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Significant Noncash Transactions [Line Items]
Interest paid	$ 122,801	$ 39,384	$ 22,069
Income taxes paid	25,718	35,770	39,824
Transfers of loans to foreclosed assets held for sale
Other Significant Noncash Transactions [Line Items]
Real estate transferred	16,858	6,983	4,604
Transfers of premises to foreclosed assets and other real estate owned
Other Significant Noncash Transactions [Line Items]
Real estate transferred	3,690	5,422	0
Transfers of premises held for sale to foreclosed assets and other real estate owned
Other Significant Noncash Transactions [Line Items]
Real estate transferred	$ 0	$ 3,188	$ 652

Other Operating Expenses (Detai

Other Operating Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Income and Expenses [Abstract]
Professional services	$ 16,685	$ 19,500	$ 14,630
Postage	5,785	4,686	4,599
Telephone	5,947	4,262	4,294
Credit card expense	14,338	12,188	11,328
Marketing	8,410	11,141	6,929
Operating supplies	2,346	1,980	1,824
Amortization of intangibles	11,009	7,668	5,945
Branch right sizing expense	1,341	434	3,600
Other expense	45,714	27,020	20,364
Total other operating expenses	$ 111,575	$ 88,879	$ 73,513

Other Operating Expenses - Rent

Other Operating Expenses - Rental Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Leased Assets [Line Items]
Equipment expense	$ 16,323	$ 19,366	$ 16,683
Equipment Rentals
Operating Leased Assets [Line Items]
Equipment expense	2,922	2,200	2,300
Leasing of ATMs
Operating Leased Assets [Line Items]
Equipment expense	1,697	1,335	1,338
Occupancy Expense
Operating Leased Assets [Line Items]
Operating leases, rent expense	$ 10,456	$ 5,580	$ 4,643

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Financial Assets Measure on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	$ 2,151,752	$ 1,589,517
U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	154,301	139,724
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	1,522,900	1,187,317
State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	314,843	143,165
Other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	159,708	119,311
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets held for sale	1,790	165,780
Derivative asset	6,242	3,634
Other liabilities held for sale	(162)	(157,366)
Derivative liability	(5,283)	(3,068)
Fair Value, Measurements, Recurring | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	154,301	139,724
Fair Value, Measurements, Recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	1,522,900	1,187,317
Fair Value, Measurements, Recurring | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	314,843	143,165
Fair Value, Measurements, Recurring | Other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	159,708	119,311
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets held for sale	0	0
Derivative asset	0	0
Other liabilities held for sale	0	0
Derivative liability	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets held for sale	0	0
Derivative asset	6,242	3,634
Other liabilities held for sale	0	0
Derivative liability	(5,283)	(3,068)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	154,301	139,724
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	1,522,900	1,187,317
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	314,843	143,165
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	159,708	119,311
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets held for sale	1,790	165,780
Derivative asset	0	0
Other liabilities held for sale	(162)	(157,366)
Derivative liability	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	$ 0	$ 0

Fair Value Measurements (Detail

Fair Value Measurements (Details)	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed assets and other real estate owned	$ 25,565,000	$ 32,118,000
Impairment of financing receivable, held-for-sale	0
Mortgage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of financing receivable, held-for-sale	$ 0
Measurement Input, Discount Rate | Commercial Real Estate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned, measurement input	0.10
Measurement Input, Discount Rate | Commercial Real Estate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned, measurement input	0.40
Foreclosed Assets Not Covered By FDIC Loss Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed assets and other real estate owned	$ 25,600,000	$ 32,100,000
Criticized
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Threshold value for performing impairment testing on loans	$ 1,500,000

Fair Value Measurements - Fai_2

Fair Value Measurements - Fair Value of Financial Assets Measured on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans, related allowance	$ 684	$ 338
Collateral Pledged
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans, related allowance	2,738	2,195
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (collateral dependent)	17,789	11,229
Foreclosed assets and other real estate owned	23,714	24,093
Fair Value, Measurements, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (collateral dependent)	0	0
Foreclosed assets and other real estate owned	0	0
Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (collateral dependent)	0	0
Foreclosed assets and other real estate owned	0	0
Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (collateral dependent)	17,789	11,229
Foreclosed assets and other real estate owned	$ 23,714	$ 24,093

Fair Value Measurements - Estim

Fair Value Measurements - Estimated Fair Values and Related Carrying Amounts of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	$ 290,830	$ 373,298
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	833,458	598,042
Interest bearing balances due from banks - time	4,934	3,314
Held-to-maturity securities	289,194	368,058
Mortgage loans held for sale	26,799	24,038
Interest receivable	49,938	43,528
Federal funds purchased and securities sold under agreements to repurchase	95,792	122,444
Other borrowings	1,345,450	1,380,024
Subordinated notes and debentures	353,950	140,565
Interest payable	9,897	4,564
Carrying Amount | Non-interest bearing transaction accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	2,672,405	2,665,249
Carrying Amount | Interest bearing transaction accounts and savings deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	6,830,191	6,494,896
Carrying Amount | Time deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	2,896,156	1,932,730
Carrying Amount | Legacy loans, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	8,373,789	5,663,941
Carrying Amount | Loans acquired, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	3,292,783	5,074,076
Fair Value Measurements
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	833,458	598,042
Interest bearing balances due from banks - time	4,934	3,314
Held-to-maturity securities	290,830	373,298
Mortgage loans held for sale	26,799	24,038
Interest receivable	49,938	43,528
Federal funds purchased and securities sold under agreements to repurchase	95,792	122,444
Other borrowings	1,342,868	1,381,365
Subordinated notes and debentures	355,812	136,474
Interest payable	9,897	4,564
Fair Value Measurements | Non-interest bearing transaction accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	2,672,405	2,665,249
Fair Value Measurements | Interest bearing transaction accounts and savings deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	6,830,191	6,494,896
Fair Value Measurements | Time deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	2,872,342	1,915,539
Fair Value Measurements | Legacy loans, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	8,280,690	5,646,505
Fair Value Measurements | Loans acquired, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	3,256,174	5,058,455
Fair Value Measurements | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	833,458	598,042
Interest bearing balances due from banks - time	0	0
Held-to-maturity securities	0	0
Mortgage loans held for sale	0	0
Interest receivable	0	0
Federal funds purchased and securities sold under agreements to repurchase	0	0
Other borrowings	0	0
Subordinated notes and debentures	0	0
Interest payable	0	0
Fair Value Measurements | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-interest bearing transaction accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest bearing transaction accounts and savings deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements | Quoted Prices in Active Markets for Identical Assets (Level 1) | Time deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements | Quoted Prices in Active Markets for Identical Assets (Level 1) | Legacy loans, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	0	0
Fair Value Measurements | Quoted Prices in Active Markets for Identical Assets (Level 1) | Loans acquired, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	0	0
Fair Value Measurements | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Interest bearing balances due from banks - time	4,934	3,314
Held-to-maturity securities	290,830	373,298
Mortgage loans held for sale	0	0
Interest receivable	49,938	43,528
Federal funds purchased and securities sold under agreements to repurchase	95,792	122,444
Other borrowings	1,342,868	1,381,365
Subordinated notes and debentures	355,812	136,474
Interest payable	9,897	4,564
Fair Value Measurements | Significant Other Observable Inputs (Level 2) | Non-interest bearing transaction accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	2,672,405	2,665,249
Fair Value Measurements | Significant Other Observable Inputs (Level 2) | Interest bearing transaction accounts and savings deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	6,830,191	6,494,896
Fair Value Measurements | Significant Other Observable Inputs (Level 2) | Time deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements | Significant Other Observable Inputs (Level 2) | Legacy loans, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	0	0
Fair Value Measurements | Significant Other Observable Inputs (Level 2) | Loans acquired, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	0	0
Fair Value Measurements | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Interest bearing balances due from banks - time	0	0
Held-to-maturity securities	0	0
Mortgage loans held for sale	26,799	24,038
Interest receivable	0	0
Federal funds purchased and securities sold under agreements to repurchase	0	0
Other borrowings	0	0
Subordinated notes and debentures	0	0
Interest payable	0	0
Fair Value Measurements | Significant Unobservable Inputs (Level 3) | Non-interest bearing transaction accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements | Significant Unobservable Inputs (Level 3) | Interest bearing transaction accounts and savings deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements | Significant Unobservable Inputs (Level 3) | Time deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	2,872,342	1,915,539
Fair Value Measurements | Significant Unobservable Inputs (Level 3) | Legacy loans, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	8,280,690	5,646,505
Fair Value Measurements | Significant Unobservable Inputs (Level 3) | Loans acquired, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	$ 3,256,174	$ 5,058,455

Commitments and Credit Risk (De

Commitments and Credit Risk (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Other Commitments [Line Items]
Outstanding letters of credit	$ 39,101,000	$ 47,621,000
Standby Letters of Credit
Other Commitments [Line Items]
Deferred revenue	$ 0	0
Minimum
Other Commitments [Line Items]
Term of letter of credit	9 months
Maximum
Other Commitments [Line Items]
Term of letter of credit	15 years
Credit Card Commitments
Other Commitments [Line Items]
Outstanding commitments to extend credit	$ 560,863,000	564,592,000
Other Loan Commitments
Other Commitments [Line Items]
Outstanding commitments to extend credit	$ 3,455,471,000	$ 3,086,696,000

New Accounting Standards (Detai

New Accounting Standards (Details) - Scenario, Plan - Accounting Standards Update 2016-02 $ in Millions	Jan. 01, 2019USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets	$ 32
Right-of-use liabilities	$ 32

Stockholders' Equity (Details)

Stockholders' Equity (Details) $ in Millions	Dec. 31, 2018USD ($)
Equity [Abstract]
Statutory amount available for dividend payments without regulatory approval	$ 32.3

Stockholders' Equity - Company'

Stockholders' Equity - Company's Significant Subsidiaries (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Simmons First National Corporation
Capital	$ 1,778,938	$ 1,388,970
Capital to Risk Weighted Assets	13.30%	11.40%
Capital Required for Capital Adequacy	$ 1,070,038	$ 974,716
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital	$ 1,361,380	$ 1,199,457
Tier One Risk Based Capital to Risk Weighted Assets	10.20%	9.80%
Tier One Risk Based Capital Required for Capital Adequacy	$ 800,812	$ 734,361
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
Common Equity Tier One Capital	$ 1,361,380	$ 1,199,457
Common Equity Tier One Capital Ratio	10.20%	9.80%
Common Equity Tier One Capital Required for Capital Adequacy	$ 600,609	$ 550,771
Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Tier One Leverage Capital	$ 1,361,380	$ 1,199,457
Tier One Leverage Capital to Average Assets	8.80%	9.20%
Tier One Leverage Capital Required for Capital Adequacy	$ 618,809	$ 521,503
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Simmons Bank
Capital	$ 1,532,864	$ 877,728
Capital to Risk Weighted Assets	11.50%	12.10%
Capital Required for Capital Adequacy	$ 1,066,340	$ 580,316
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Capital Required to be Well Capitalized	$ 1,332,925	$ 725,395
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Tier One Risk Based Capital	$ 1,469,260	$ 835,787
Tier One Risk Based Capital to Risk Weighted Assets	11.00%	11.50%
Tier One Risk Based Capital Required for Capital Adequacy	$ 801,415	$ 436,063
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
Tier One Risk Based Capital Required to be Well Capitalized	$ 1,068,553	$ 581,417
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Common Equity Tier One Capital	$ 1,469,260	$ 835,787
Common Equity Tier One Capital Ratio	11.00%	11.50%
Common Equity Tier One Capital Required for Capital Adequacy	$ 601,061	$ 327,047
Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Common Equity Tier One Capital Required to be Well-Capitalized	$ 868,199	$ 472,401
Common Equity Tier One Capital Required to Be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
Tier One Leverage Capital	$ 1,469,260	$ 835,787
Tier One Leverage Capital to Average Assets	9.50%	9.20%
Tier One Leverage Capital Required for Capital Adequacy	$ 618,636	$ 363,386
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 773,295	$ 454,232
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Bank SNB
Capital		$ 259,077
Capital to Risk Weighted Assets		10.90%
Capital Required for Capital Adequacy		$ 190,148
Capital Required for Capital Adequacy to Risk Weighted Assets		8.00%
Capital Required to be Well Capitalized		$ 237,685
Capital Required to be Well Capitalized to Risk Weighted Assets		10.00%
Tier One Risk Based Capital		$ 255,360
Tier One Risk Based Capital to Risk Weighted Assets		10.70%
Tier One Risk Based Capital Required for Capital Adequacy		$ 143,193
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets		6.00%
Tier One Risk Based Capital Required to be Well Capitalized		$ 190,923
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets		8.00%
Common Equity Tier One Capital		$ 255,360
Common Equity Tier One Capital Ratio		10.70%
Common Equity Tier One Capital Required for Capital Adequacy		$ 107,394
Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets		4.50%
Common Equity Tier One Capital Required to be Well-Capitalized		$ 155,125
Common Equity Tier One Capital Required to Be Well Capitalized to Risk Weighted Assets		6.50%
Tier One Leverage Capital		$ 255,360
Tier One Leverage Capital to Average Assets		10.10%
Tier One Leverage Capital Required for Capital Adequacy		$ 101,133
Tier One Leverage Capital Required for Capital Adequacy to Average Assets		4.00%
Tier One Leverage Capital Required to be Well Capitalized		$ 126,416
Tier One Leverage Capital Required to be Well Capitalized to Average Assets		5.00%
Southwest Bank
Capital		$ 297,164
Capital to Risk Weighted Assets		11.00%
Capital Required for Capital Adequacy		$ 216,119
Capital Required for Capital Adequacy to Risk Weighted Assets		8.00%
Capital Required to be Well Capitalized		$ 270,149
Capital Required to be Well Capitalized to Risk Weighted Assets		10.00%
Tier One Risk Based Capital		$ 294,874
Tier One Risk Based Capital to Risk Weighted Assets		10.90%
Tier One Risk Based Capital Required for Capital Adequacy		$ 162,316
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets		6.00%
Tier One Risk Based Capital Required to be Well Capitalized		$ 216,421
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets		8.00%
Common Equity Tier One Capital		$ 294,874
Common Equity Tier One Capital Ratio		10.90%
Common Equity Tier One Capital Required for Capital Adequacy		$ 121,737
Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets		4.50%
Common Equity Tier One Capital Required to be Well-Capitalized		$ 175,842
Common Equity Tier One Capital Required to Be Well Capitalized to Risk Weighted Assets		6.50%
Tier One Leverage Capital		$ 294,874
Tier One Leverage Capital to Average Assets		12.20%
Tier One Leverage Capital Required for Capital Adequacy		$ 96,680
Tier One Leverage Capital Required for Capital Adequacy to Average Assets		4.00%
Tier One Leverage Capital Required to be Well Capitalized		$ 120,850
Tier One Leverage Capital Required to be Well Capitalized to Average Assets		5.00%

Condensed Financial Informati_3

Condensed Financial Information (Parent Company Only) - Condensed Balance Sheets (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ASSETS
Cash and cash equivalents		$ 833,458	$ 598,042
Loans		11,666,572	10,738,017
Premises and equipment		295,060	287,249
Other assets		68,084	71,439
Total assets		16,543,337	15,055,806
LIABILITIES
Long-term debt		369,400
Total liabilities		14,296,903	12,971,242
Stockholders’ equity:
Common stock	[1]	923	920
Surplus		1,597,944	1,586,034
Accumulated other comprehensive loss		674,941	514,874
Total stockholders’ equity		2,246,434	2,084,564	$ 1,151,111	$ 1,076,855
Total liabilities and stockholders’ equity		16,543,337	15,055,806
Parent Company
ASSETS
Cash and cash equivalents		219,063	19,101
Investment securities		2,848	2,789
Investments in wholly-owned subsidiaries		2,368,870	2,288,687
Loans		774	993
Intangible assets, net		133	133
Premises and equipment		5,804	10,369
Other assets		29,974	31,181
Total assets		2,627,466	2,353,253
LIABILITIES
Short-term debt		0	75,000
Long-term debt		353,950	183,947
Other liabilities		27,082	9,742
Total liabilities		381,032	268,689
Stockholders’ equity:
Common stock		923	920
Surplus		1,597,944	1,586,034
Accumulated other comprehensive loss		674,941	514,874
Unrealized depreciation on available-for-sale securities, net of income taxes of ($9,686) and ($6,108) at December 31, 2018 and 2017 respectively		(27,374)	(17,264)
Total stockholders’ equity		2,246,434	2,084,564
Total liabilities and stockholders’ equity		$ 2,627,466	$ 2,353,253
[1]	On April 19, 2018, shareholders of the Company approved an increase in the number of authorized shares from 120,000,000 to 175,000,000.

Condensed Financial Informati_4

Condensed Financial Information (Parent Company Only) - Condensed Balance Sheets 2 (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Parent Company
Unrealized depreciation on available-for-sale securities, net of income taxes	$ (9,686)	$ (6,108)

Condensed Financial Informati_5

Condensed Financial Information (Parent Company Only) - Condensed Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Provision for income taxes	$ 50,358	$ 61,983	$ 46,624
NET INCOME	215,713	92,940	96,814
Preferred stock dividends	0	0	24
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	215,713	92,940	96,790
Parent Company
Income Statement [Abstract]
Dividends from subsidiaries	145,980	69,107	83,710
Other income	658	4,111	2,465
Income	146,638	73,218	86,175
EXPENSE	32,714	32,234	21,990
Income before income taxes and equity in undistributed net income of subsidiaries	113,924	40,984	64,185
Provision for income taxes	(10,732)	(12,311)	(7,557)
Income before equity in undistributed net income of subsidiaries	124,656	53,295	71,742
Equity in undistributed net income of subsidiaries	91,057	39,645	25,072
NET INCOME	215,713	92,940	96,814
Preferred stock dividends	0	0	24
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 215,713	$ 92,940	$ 96,790

Condensed Financial Informati_6

Condensed Financial Information (Parent Company Only) - Condensed Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
NET INCOME	$ 215,713	$ 92,940	$ 96,814
OTHER COMPREHENSIVE INCOME (LOSS)
Equity in other comprehensive (loss) income of subsidiaries	(10,110)	964	(12,547)
COMPREHENSIVE INCOME	205,603	93,904	84,267
Parent Company
NET INCOME	215,713	92,940	96,814
OTHER COMPREHENSIVE INCOME (LOSS)
Equity in other comprehensive (loss) income of subsidiaries	(10,110)	964	(12,547)
COMPREHENSIVE INCOME	$ 205,603	$ 93,904	$ 84,267

Condensed Financial Informati_7

Condensed Financial Information (Parent Company Only) - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES
Net income	$ 215,713	$ 92,940	$ 96,814
Items not requiring (providing) cash
Stock-based compensation expense	9,725	10,681	3,418
Deferred income taxes	8,412	23,251	9,832
Changes in
Other assets	(1,414)	12,456	(8,206)
Net cash provided by operating activities	260,679	114,563	91,134
INVESTING ACTIVITIES
Net originations of loans	(912,793)	(719,219)	(368,162)
Repayment of (advances to) subsidiaries	(55,211)	0	0
Proceeds from maturities of available-for-sale securities	258,325	487,717	257,388
Purchases of available-for-sale securities	(825,914)	(854,708)	(861,572)
Net cash used in investing activities	(1,428,821)	(338,471)	(250,949)
FINANCING ACTIVITIES
Proceeds from issuance of subordinated notes	326,355	0	0
Dividends paid on preferred stock	0	0	(24)
Dividends paid on common stock	(55,646)	(35,116)	(28,743)
Redemption of preferred stock	0	0	(30,852)
Net cash provided by financing activities	1,403,558	536,291	193,212
INCREASE IN CASH EQUIVALENTS	235,416	312,383	33,397
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	598,042	285,659	252,262
CASH AND CASH EQUIVALENTS, END OF YEAR	833,458	598,042	285,659
Parent Company
OPERATING ACTIVITIES
Net income	215,713	92,940	96,814
Items not requiring (providing) cash
Stock-based compensation expense	9,725	10,681	3,418
Depreciation and amortization	880	1,183	700
Deferred income taxes	26	1,190	(2,526)
Equity in undistributed net income of bank subsidiaries	(91,057)	(39,645)	(25,072)
Changes in
Other assets	1,524	8,585	2,816
Other liabilities	17,340	(6,769)	(1,358)
Net cash provided by operating activities	154,151	68,165	74,792
INVESTING ACTIVITIES
Net originations of loans	219	90	(1,710)
Net proceeds from (purchases of) premises and equipment	3,342	(18)	(6,896)
Repayment of (advances to) subsidiaries	2,667	(15,000)	0
Proceeds from maturities of available-for-sale securities	152	42	1,973
Purchases of available-for-sale securities	(211)	(2,752)	(3)
Cash paid in business combinations	0	(100,468)	(35,048)
Other, net	(1,903)	0	0
Net cash used in investing activities	4,266	(118,106)	(41,684)
FINANCING ACTIVITIES
Proceeds from issuance of subordinated notes	326,355	0	0
Issuance (repayment) of long-term debt, net	(231,352)	8,014	(4,544)
Issuance of common stock, net	2,188	2,878	4,938
Dividends paid on preferred stock	0	0	(24)
Dividends paid on common stock	(55,646)	(35,116)	(28,743)
Redemption of preferred stock	0	0	(30,852)
Net cash provided by financing activities	41,545	(24,224)	(59,225)
INCREASE IN CASH EQUIVALENTS	199,962	(74,165)	(26,117)
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	19,101	93,266	119,383
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 219,063	$ 19,101	$ 93,266