International Bancshares (IBOC) 10-Q 6 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 01, 2019
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2019
Entity File Number	000-09439
Entity Registrant Name	INTERNATIONAL BANCSHARES CORPORATION
Entity Incorporation, State or Country Code	TX
Entity Tax Identification Number	74-2157138
Entity Address, Address Line One	1200 San Bernardo Avenue
Entity Address, City or Town	Laredo
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	78042-1359
City Area Code	956
Local Phone Number	722-7611
Title of 12(b) Security	Common Stock
Trading Symbol	IBOC
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		65,195,349
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Central Index Key	0000315709
Amendment Flag	false

Consolidated Statements of Cond

Consolidated Statements of Condition - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Cash and cash equivalents	$ 286,519	$ 316,797
Investment securities:
Held to maturity debt securities (Market value of $2,400 on September 30, 2019 and 1,200 on December 31, 2018)	2,400	1,200
Available for sale debt securities (Amortized cost of $3,187,248 on September 30, 2019 and $3,481,165 on December 31, 2018)	3,192,872	3,411,350
Equity securities with readily determinable fair values	6,172	5,937
Total investment securities	3,201,444	3,418,487
Loans	6,895,142	6,561,289
Less allowance for probable loan losses	(59,860)	(61,384)
Net loans	6,835,282	6,499,905
Bank premises and equipment, net	507,945	506,899
Accrued interest receivable	35,359	36,803
Other investments	307,010	337,507
Cash surrender value of life insurance policies	287,871	282,646
Goodwill	282,532	282,532
Other assets	222,073	190,376
Total assets	11,966,035	11,871,952
Deposits:
Demand - non-interest bearing	3,575,930	3,454,840
Savings and interest bearing demand	3,254,762	3,268,237
Time	1,981,369	1,973,468
Total deposits	8,812,061	8,696,545
Securities sold under repurchase agreements	289,334	229,989
Other borrowed funds	456,556	705,665
Junior subordinated deferrable interest debentures	134,642	160,416
Other liabilities	205,518	139,755
Total liabilities	9,898,111	9,932,370
Shareholders' equity:
Common shares of $1.00 par value. Authorized 275,000,000 shares; issued 96,191,692 shares on September 30, 2019 and 96,104,029 shares on December 31, 2018	96,192	96,104
Surplus	147,456	145,283
Retained earnings	2,148,835	2,064,134
Accumulated other comprehensive income (loss)	4,563	(54,634)
Total shareholders' equity before treasury stock	2,397,046	2,250,887
Less cost of shares in treasury, 31,014,374 shares on September 30, 2019 and 30,494,143 on December 31, 2018	(329,122)	(311,305)
Total shareholders' equity	2,067,924	1,939,582
Total liabilities and shareholders' equity	$ 11,966,035	$ 11,871,952

Consolidated Statements of Co_2

Consolidated Statements of Condition (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Consolidated Statements of Condition
Held to maturity, Fair value (in dollars)	$ 2,400	$ 1,200
Available for sale, Amortized cost (in dollars)	$ 3,187,248	$ 3,481,165
Common shares, par value (in dollars per share)	$ 1	$ 1
Common shares, Authorized shares	275,000,000	275,000,000
Common shares, issued shares	96,191,692	96,104,029
Treasury, shares	31,014,374	30,494,143

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest income:
Loans, including fees	$ 104,688	$ 95,828	$ 313,057	$ 275,744
Investment securities:
Taxable	18,040	20,213	56,942	62,121
Tax-exempt	1,019	1,981	4,045	6,263
Other interest income	372	352	998	719
Total interest income	124,119	118,374	375,042	344,847
Interest expense:
Savings deposits	4,023	3,353	12,515	8,872
Time deposits	5,680	3,493	15,102	9,172
Securities sold under repurchase agreements	640	468	1,820	1,839
Other borrowings	3,144	4,358	10,151	13,426
Junior subordinated deferrable interest debentures	1,414	1,828	5,045	5,119
Total interest expense	14,901	13,500	44,633	38,428
Net interest income	109,218	104,874	330,409	306,419
Provision for probable loan losses	5,278	4,280	15,363	3,212
Net interest income after provision for probable loan losses	103,940	100,594	315,046	303,207
Non-interest income:
Investment securities transactions, net	(2)	(141)	(12)	(141)
Other investments, net	2,440	5,625	4,685	16,192
Other income	4,813	3,643	11,866	13,425
Total non-interest income	42,697	42,503	113,242	123,781
Non-interest expense:
Employee compensation and benefits	37,038	35,360	110,693	104,670
Occupancy	7,294	6,839	20,251	20,077
Depreciation of bank premises and equipment	7,127	6,460	21,140	19,097
Professional fees	4,744	4,063	12,081	10,010
Deposit insurance assessments	829	928	2,471	2,902
Net expense, other real estate owned	1,578	911	3,776	3,289
Advertising	1,987	2,020	6,150	5,667
Software and software maintenance	4,691	4,481	14,191	12,943
Other	15,778	17,005	42,877	48,922
Total non-interest expense	81,066	78,067	233,630	227,577
Income before income taxes	65,571	65,030	194,658	199,411
Provision for income taxes	14,127	13,935	41,288	42,009
Net income	$ 51,444	$ 51,095	$ 153,370	$ 157,402
Basic earnings per common share:
Weighted average number of shares outstanding (in shares)	65,449,159	66,136,091	65,571,124	66,114,482
Net income (in dollars per share)	$ 0.79	$ 0.77	$ 2.34	$ 2.38
Fully diluted earnings per common share:
Weighted average number of shares outstanding (in shares)	65,636,116	66,423,209	65,777,552	66,739,899
Net income (in dollars per share)	$ 0.78	$ 0.77	$ 2.33	$ 2.36
Services charges on deposit accounts
Non-interest income:
Service charges	$ 18,723	$ 18,391	$ 53,593	$ 53,658
Other service charges, commissions and fees, Banking
Non-interest income:
Service charges	14,708	13,100	37,348	35,374
Other service charges, commissions and fees, Non-banking
Non-interest income:
Service charges	$ 2,015	$ 1,885	$ 5,762	$ 5,273

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Consolidated Statements of Comprehensive Income
Net income	$ 51,444	$ 51,095	$ 153,370	$ 157,402
Other comprehensive income (loss), net of tax:
Net unrealized holding gains (losses) on securities available for sale arising during period (net of tax effects of $2,343, $(4,193), $15,733, and $(17,787))	8,813	(15,772)	59,188	(66,912)
Reclassification adjustment for losses on securities available for sale included in net income (net of tax effects of $0, $30, $3 and $30)	2	111	9	111
Other comprehensive income, net of tax	8,815	(15,661)	59,197	(66,801)
Comprehensive income	$ 60,259	$ 35,434	$ 212,567	$ 90,601

Consolidated Statements of Co_3

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Consolidated Statements of Comprehensive Income
Net unrealized holding gains (losses) on securities available for sale arising during period, tax effects	$ 2,343	$ (4,193)	$ 15,733	$ (17,787)
Reclassification adjustment for losses on securities available for sale included in net income, tax effects	$ 0	$ 30	$ 3	$ 30

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Surplus	Retained Earnings	Other Comprehensive Income (Loss)	Treasury Stock	Total
Dividends:
Cumulative adjustment for adoption of new accounting standards			$ 5,997	$ (5,997)
Balance at Dec. 31, 2017	$ 96,019	$ 171,816	1,891,805	(28,397)	$ (292,263)	$ 1,838,980
Balance (in shares) at Dec. 31, 2017	96,019
Increase (decrease) in shareholders' equity
Net Income			157,402			157,402
Dividends:
Dividends			(49,598)			(49,598)
Purchase of treasury stock					(57)	(57)
Exercise of stock options	$ 64	1,094				1,158
Exercise of stock options (in shares)	64
Stock compensation expense recognized in earnings		755				755
Repurchase of outstanding warrant		(29,005)				(29,005)
Other comprehensive income (loss), net of tax:
Net change in unrealized gains and losses on available for sale securities, net of reclassification adjustments				(60,790)		(60,790)
Balance at Sep. 30, 2018	$ 96,083	144,660	2,005,606	(95,184)	(292,320)	1,858,845
Balance (in shares) at Sep. 30, 2018	96,083
Dividends:
Cumulative adjustment for adoption of new accounting standards			(170)	170
Balance at Jun. 30, 2018	$ 96,066	173,057	1,982,464	(79,537)	(292,320)	1,879,730
Balance (in shares) at Jun. 30, 2018	96,066
Increase (decrease) in shareholders' equity
Net Income			51,095			51,095
Dividends:
Dividends			(27,783)			(27,783)
Exercise of stock options	$ 17	323				340
Exercise of stock options (in shares)	17
Stock compensation expense recognized in earnings		285				285
Repurchase of outstanding warrant		(29,005)				(29,005)
Other comprehensive income (loss), net of tax:
Net change in unrealized gains and losses on available for sale securities, net of reclassification adjustments				(15,817)		(15,817)
Balance at Sep. 30, 2018	$ 96,083	144,660	2,005,606	(95,184)	(292,320)	1,858,845
Balance (in shares) at Sep. 30, 2018	96,083
Balance at Dec. 31, 2018	$ 96,104	145,283	2,064,134	(54,634)	(311,305)	1,939,582
Balance (in shares) at Dec. 31, 2018	96,104
Increase (decrease) in shareholders' equity
Net Income			153,370			153,370
Dividends:
Dividends			(68,669)			(68,669)
Purchase of treasury stock					(17,817)	(17,817)
Exercise of stock options	$ 88	1,429				1,517
Exercise of stock options (in shares)	88
Stock compensation expense recognized in earnings		744				744
Other comprehensive income (loss), net of tax:
Net change in unrealized gains and losses on available for sale securities, net of reclassification adjustments				59,197		59,197
Balance at Sep. 30, 2019	$ 96,192	147,456	2,148,835	4,563	(329,122)	2,067,924
Balance (in shares) at Sep. 30, 2019	96,192
Balance at Jun. 30, 2019	$ 96,151	146,614	2,133,239	(4,252)	(311,433)	2,060,319
Balance (in shares) at Jun. 30, 2019	96,151
Increase (decrease) in shareholders' equity
Net Income			51,444			51,444
Dividends:
Dividends			(35,848)			(35,848)
Purchase of treasury stock					(17,689)	(17,689)
Exercise of stock options	$ 41	602				643
Exercise of stock options (in shares)	41
Stock compensation expense recognized in earnings		240				240
Other comprehensive income (loss), net of tax:
Net change in unrealized gains and losses on available for sale securities, net of reclassification adjustments				8,815		8,815
Balance at Sep. 30, 2019	$ 96,192	$ 147,456	$ 2,148,835	$ 4,563	$ (329,122)	$ 2,067,924
Balance (in shares) at Sep. 30, 2019	96,192

Consolidated Statements of Sh_2

Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Consolidated Statements of Shareholders' Equity
Cash Dividends (in dollars per share)	$ 0.55	$ 0.42	$ 1.05	$ 0.75
Purchase of treasury stock (in shares)	516,973		3,258	1,298

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities:
Net income	$ 153,370	$ 157,402
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for probable loan losses	15,363	3,212
Specific reserve, other real estate owned	154	3,033
Depreciation of bank premises and equipment	21,140	19,097
Gain on sale of bank premises and equipment	(207)	(293)
Gain on sale of other real estate owned	(1,246)	(1,317)
Accretion of investment securities discounts	(311)	(209)
Amortization of investment securities premiums	13,678	15,620
Investment securities transactions, net	12	141
Unrealized loss on equity securities with readily determinable fair values	(235)	312
Stock based compensation expense	744	755
Earnings from affiliates and other investments	(2,869)	(12,247)
Deferred tax expense	330	1,373
Decrease in accrued interest receivable	1,444	65
Increase in other assets	(17,430)	(48,747)
Net increase in other liabilities	27,250	40,533
Net cash provided by operating activities	211,187	178,730
Investing activities:
Proceeds from maturities of securities		1,075
Proceeds from sales and calls of available for sale securities	92,980	37,675
Proceeds from sales of equity securities with readily determinable fair values		21,607
Purchases of available for sale securities	(380,095)	(47,346)
Principal collected on mortgage backed securities	566,455	529,956
Net increase in loans	(372,121)	(168,823)
Purchases of other investments	(33,940)	(34,914)
Distributions from other investments	52,693	2,894
Purchases of bank premises and equipment	(23,809)	(16,256)
Proceeds from sales of bank premises and equipment	3,685	3,633
Proceeds from sales of other real estate owned	1,830	1,413
Net cash (used in) provided by investing activities	(92,322)	330,914
Financing activities:
Net increase in non-interest bearing demand deposits	121,090	188,518
Net decrease in savings and interest bearing demand deposits	(13,475)	(13,938)
Net increase (decrease) in time deposits	7,901	(73,871)
Net increase (decrease) in securities sold under repurchase agreements	59,345	(20,002)
Net decrease in other borrowed funds	(249,109)	(520,325)
Redemption of long-term debt	(25,774)
Repurchase of outstanding common stock warrant		(29,005)
Purchase of treasury stock	(17,817)	(57)
Proceeds from stock transactions	1,517	1,158
Payments of cash dividends - common	(32,821)	(21,815)
Net cash used in financing activities	(149,143)	(489,337)
(Decrease) increase in cash and cash equivalents	(30,278)	20,307
Cash and cash equivalents at beginning of period	316,797	265,357
Cash and cash equivalents at end of period	286,519	285,664
Supplemental cash flow information:
Interest paid	43,262	37,051
Income taxes paid	38,591	39,715
Non-cash investing and financing activities:
Net transfers from loans to other real estate owned	21,381	31,609
Dividends declared, not yet paid on common stock	35,848	$ 27,784
Establishment of lease liability and right-of-use asset	$ 6,171

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Basis of Presentation
Basis of Presentation	Note 1 — Basis of Presentation ​ Our accounting and reporting policies conform to accounting principles generally accepted in the United States of America and to general practices within the banking industry. Our consolidated financial statements include the accounts of International Bancshares Corporation, and our wholly-owned bank subsidiaries, International Bank of Commerce, Laredo (“IBC”), Commerce Bank, International Bank of Commerce, Zapata, International Bank of Commerce, Brownsville, International Bank of Commerce, Oklahoma (the “Subsidiary Banks”) and our wholly-owned non-bank subsidiaries, IBC Trading Company, Premier Tierra Holdings, Inc., IBC Charitable and Community Development Corporation, and IBC Capital Corporation. Effective January 1, 2019, we dissolved one of our non-bank subsidiaries, IBC Subsidiary Corporation, a second-tier bank holding company incorporated in the State of Delaware. All significant inter-company balances and transactions have been eliminated in consolidation. Our consolidated financial statements are unaudited, but include all adjustments, which, in the opinion of management, are necessary for a fair presentation of the results of the periods presented. All such adjustments were of a normal and recurring nature. These financial statements should be read in conjunction with the financial statements and the notes thereto in our latest Annual Report on Form 10-K. Our consolidated statement of condition at December 31, 2018 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States of America (“US GAAP”) for complete financial statements. Certain reclassifications have been made to make prior periods comparable. Operating results for the three and nine months ended September 30, 2019 are not necessarily indicative of the results for the year ending December 31, 2019 or any future period. ​ We operate as one segment. The operating information used by our chief executive officer for purposes of assessing performance and making operating decisions is the consolidated statements presented in this report. We have five active operating subsidiaries, the Subsidiary Banks. We apply the provisions of Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”), FASB ASC 280, “Segment Reporting,” in determining our reportable segments and related disclosures. ​ We have evaluated all events or transactions that occurred through the date we issued these financial statements. During this period, we did not have any material recognizable or non-recognizable subsequent events. ​ On January 1, 2019, we adopted the provisions of ASU 2016-02, “Leases.” ASU 2016-02 amends existing standards for accounting for leases by lessees, with accounting for leases by lessors remaining mainly unchanged from current guidance. The update requires that lessees recognize a lease liability and a right of use asset for all leases (with the exception of short-term leases) at the commencement date of the lease and disclose key information about leasing arrangements. The update is to be applied on a modified retrospective basis for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the consolidated financial statements. In January 2018, the FASB issued a proposal that provides an additional transition method that would allow entities to not apply the guidance in the update in the comparative periods presented in the consolidated financial statements, but instead recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. As part of our business model, we primarily own all property we occupy, with the exception of certain branches operating in grocery stores or shopping centers and certain ATM locations that were classified as operating leases under previous guidance. The adoption of the standard did not have a significant impact on our consolidated financial statements. As of the date of adoption, we recorded a right of use asset and a lease million. The right of use asset and lease liability are included in other and other liabilities, respectively, on our consolidated statement of condition. Amortization of the right of use asset for the three and nine months ended ​ In June 2016, the FASB issued Accounting Standards Update No. 2016-13 to ASC 326, “Financial Instruments – Credit Losses.” The update amends existing standards for accounting for credit losses for financial assets. The update requires that the expected credit losses on the financial instruments held as of the end of the period being reported be measured based on historical experience, current conditions, and reasonable and supportable forecasts. The update also expands the required disclosures related to significant estimates and judgements used in estimating credit losses, as well as the credit quality and underwriting standards of an organization’s financial assets. The update also amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The impact of the adoption of the standard is to be recorded as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The accounting standard will be effective for us on January 1, 2020. We continue to evaluate the impact the adoption of the update will have on us and do not have a current estimate, however, we do expect that that final impact of the adoption could be significantly impacted by a change in the mix of loans, characteristics and quality of our loan portfolio at the end of the year as well the economic conditions and forecasts at the time of adoption. The task force formed last year, which includes key members of the teams that work with the current calculation of the allowance for probable loan losses with members representing the corporate accounting and risk management areas has continued to work with the implementation of the update. Initial implementation activities and decisions have been reached around key data needed for the new calculation including portfolio segmentation. Validation of our primary model/tool is substantially completed and ongoing activities around forecasting models and documentation of the process will continue during the fourth quarter of 2019.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value
Fair Value	Note 2 — Fair Value Measurements ​ ASC Topic 820, “Fair Value Measurements and Disclosures” (“ASC 820”), defines fair value, establishes a framework for measuring fair value in generally accepted accounting principles, and expands disclosures about fair value measurements. ASC 820 applies to all financial instruments that are being measured and reported on a fair value basis. ASC 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; it also establishes a fair value hierarchy that prioritizes the inputs used in valuation methodologies into the following three levels: ​ ● Level 1 Inputs - Unadjusted quoted prices in active markets for identical assets or liabilities. ● Level 2 Inputs - Observable inputs other than Level 1 inputs, such as quoted prices for similar assets or liabilities; quoted prices 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. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or other valuation techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. ​ ​ The following table represents assets and liabilities reported on the consolidated balance sheets at their fair value on a recurring basis as of September 30, 2019 by level within the fair value measurement hierarchy: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at ​ ​ ​ ​ ​ ​ Reporting Date Using ​ ​ ​ ​ ​ ​ (in Thousands) ​ ​ ​ ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Active ​ Significant ​ ​ ​ ​ ​ ​ Assets/Liabilities ​ Markets for ​ Other ​ Significant ​ ​ ​ Measured at ​ Identical ​ Observable ​ Unobservable ​ ​ ​ Fair Value ​ Assets ​ Inputs ​ Inputs ​ ​ ​ September 30, 2019 ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Measured on a recurring basis: ​ ​ ​ ​ ​ Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available for sale debt securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Residential mortgage-backed securities ​ $ 3,097,409 ​ $ — ​ $ 3,097,409 ​ $ — ​ States and political subdivisions ​ 95,462 ​ — ​ 95,462 ​ — ​ Equity Securities ​ 6,172 ​ 6,172 ​ — ​ — ​ ​ ​ $ 3,199,043 ​ $ 6,172 ​ $ 3,192,871 ​ $ — ​ ​ The following table represents assets and liabilities reported on the consolidated balance sheets at their fair value on a recurring basis as of December 31, 2018 by level within the fair value measurement hierarchy: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at ​ ​ ​ ​ ​ ​ Reporting Date Using ​ ​ ​ ​ ​ ​ (in Thousands) ​ ​ ​ ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Active ​ Significant ​ ​ ​ ​ ​ ​ Assets/Liabilities ​ Markets for ​ Other ​ Significant ​ ​ ​ Measured at ​ Identical ​ Observable ​ Unobservable ​ ​ ​ Fair Value ​ Assets ​ Inputs ​ Inputs ​ ​ ​ December 31, 2018 ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Measured on a recurring basis: ​ ​ ​ ​ ​ Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available for sale securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Residential mortgage - backed securities ​ $ 3,223,010 ​ $ — ​ $ 3,223,010 ​ $ — ​ States and political subdivisions ​ 188,340 ​ — ​ 188,340 ​ — ​ Equity Securities ​ 5,937 ​ 5,937 ​ — ​ — ​ ​ ​ $ 3,417,287 ​ $ 5,937 ​ $ 3,411,350 ​ $ — ​ ​ Available-for-sale debt securities are classified within Level 2 of the valuation hierarchy. Equity securities with readily determinable fair values are classified within Level 1. For debt investments classified as Level 2 in the fair value hierarchy, we obtain 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 bond’s terms and conditions, among other things. ​ Certain financial assets and financial liabilities are measured at fair value on a non-recurring basis. 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). ​ The following table represents financial instruments measured at fair value on a non-recurring basis as of and for the period ended September 30, 2019 by level within the fair value measurement hierarchy: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting ​ ​ ​ ​ ​ ​ ​ ​ Date Using ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assets/Liabilities ​ Prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Measured at ​ Active ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ Fair Value ​ Markets for ​ Other ​ Significant ​ Net Provision ​ ​ Period ended ​ Identical ​ Observable ​ Unobservable ​ (Credit) ​ ​ September 30, ​ Assets ​ Inputs ​ Inputs ​ During ​ ​ 2019 ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Period Measured on a non-recurring basis: ​ ​ ​ ​ ​ Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Impaired loans ​ $ 914 ​ $ — ​ $ — ​ $ 914 ​ $ 189 Other real estate owned ​ 27,376 ​ — ​ — ​ 27,376 ​ 154 Equity investments without readily determinable fair values ​ ​ 28,166 ​ ​ — ​ ​ — ​ ​ 28,166 ​ ​ 4,775 ​ The following table represents financial instruments measured at fair value on a non-recurring basis as of and for the period ended December 31, 2018 by level within the fair value measurement hierarchy: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting ​ ​ ​ ​ ​ ​ ​ ​ ​ Date Using ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assets/Liabilities ​ Prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Measured at ​ Active ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value ​ Markets ​ Other ​ Significant ​ Net (Credit) ​ ​ ​ Year ended ​ for Identical ​ Observable ​ Unobservable ​ Provision ​ ​ ​ December 31, ​ Assets ​ Inputs ​ Inputs ​ During ​ ​ ​ 2018 ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Period ​ Measured on a non-recurring basis: ​ ​ ​ ​ ​ ​ Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Impaired loans ​ $ 1,563 ​ $ — ​ $ — ​ $ 1,563 ​ $ 356 ​ Other real estate owned ​ 38,871 ​ — ​ — ​ 38,871 ​ 3,071 ​ ​ Our assets measured at fair value on a non-recurring basis are limited to impaired loans, other real estate owned, and an equity investment without a readily determinable fair value. The determination of the fair value of the equity investment without a readily determinable fair value is based on the estimated value to be received upon the sale of the investment, which is expected to occur at the end of 2019. Impaired loans are classified within Level 3 of the valuation hierarchy. The fair value of impaired loans is derived in accordance with FASB ASC 310, “Receivables”. Impaired loans are primarily comprised of collateral-dependent commercial loans. As the primary sources of loan repayments decline, the secondary repayment source, the collateral, takes on greater significance. Correctly evaluating the fair value becomes even more important. Re-measurement of the impaired loan to fair value is done through a specific valuation allowance included in the allowance for probable loan losses. The fair value of impaired loans is based on the fair value of the collateral, as determined through either an appraisal or evaluation process. The basis for our appraisal and appraisal review process is based on regulatory guidelines and strives to comply with all regulatory appraisal laws, regulations, and the Uniform Standards of Professional Appraisal Practice. All appraisals and evaluations are “as is” (the property’s highest and best use) valuations based on the current conditions of the property/project at that point in time. The determination of the fair value of the collateral is based on the net realizable value, which is the appraised value less any closing costs, when applicable. As of September 30, 2019, we had $10,666,000 of impaired commercial collateral dependent loans, of which $7,184,000 had an appraisal performed within the immediately preceding twelve months, and of which $1,490,000 had an evaluation performed within the immediately preceding twelve months. As of December 31, 2018, we had approximately $14,306,000 of impaired commercial collateral dependent loans, of which $10,911,000 had an appraisal performed within the immediately preceding twelve months and of which $0 had an evaluation performed within the immediately preceding twelve months. ​ Our determination to either seek an appraisal or to perform an evaluation begins in weekly credit quality meetings, where the committee analyzes the existing collateral values of the impaired loans and where obsolete appraisals are identified. In order to determine whether we would obtain a new appraisal or perform an internal evaluation to determine the fair value of the collateral, the credit committee reviews the existing appraisal to determine if the collateral value is reasonable in view of the current use of the collateral and the economic environment related to the collateral. If the analysis of the existing appraisal does not find that the collateral value is reasonable under the current circumstances, we would obtain a new appraisal on the collateral or perform an internal evaluation of the collateral. The ultimate decision to get a new appraisal rests with the independent credit administration group. A new appraisal is not required if an internal evaluation, as performed by in-house experts, is able to appropriately update the original appraisal assumptions to reflect current market conditions and provide an estimate of the collateral’s market value for impairment analysis. The internal evaluations must be in writing and contain sufficient information detailing the analysis, assumptions and conclusions, and they must support performing an evaluation in lieu of ordering a new appraisal. ​ Other real estate owned is comprised of real estate acquired by foreclosure and deeds in lieu of foreclosure. Other real estate owned is carried at the lower of the recorded investment in the property or its fair value less estimated costs to sell such property (as determined by independent appraisal) within Level 3 of the fair value hierarchy. Prior to foreclosure, the value of the underlying loan is written down to the fair value of the real estate to be acquired by a charge to the allowance for probable loan losses, if necessary. The fair value is reviewed periodically and subsequent write-downs are made, accordingly, through a charge to operations. Other real estate owned is included in other assets on the consolidated financial statements. For the three and nine months ended September 30, 2019 and the twelve months ended December 31, 2018, we recorded $33,000, $9,533,000, n charges to the allowance for probable loan losses in connection with loans transferred to other real estate owned. The $9,500,000 charge recorded in the second quarter of 2019 is related to the deterioration on one loan relationship discussed further in Note 4 – Allowance for Loan Losses. For the three and nine months ended September 30, 2019 and the twelve months ended December 31, 2018, we recorded $66,000, $154,000, and $3,071,000, respectively, in adjustments to fair value in connection with other real estate owned. ​ The fair value estimates, methods, and assumptions for our financial instruments at September 30, 2019 and December 31, 2018 are outlined below. ​ Cash and Cash Equivalents ​ For these short-term instruments, the carrying amount is a reasonable estimate of fair value. ​ Time Deposits with Banks ​ The carrying amounts of time deposits with banks approximate fair value. ​ Investment Securities Held-to-Maturity ​ The carrying amounts of investments held-to-maturity approximate fair value. ​ Investment Securities ​ For investment securities, which include U.S. Treasury securities, obligations of other U.S. government agencies, obligations of states and political subdivisions and mortgage pass-through and related securities, fair values are 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 bond’s terms and conditions, among other things. See disclosures of fair value of investment securities in Note 6. ​ Loans ​ Fair values are estimated for portfolios of loans with similar financial characteristics. Loans are segregated by type, such as commercial, real estate and consumer loans, as outlined by regulatory reporting guidelines. Each category is segmented into fixed and variable interest rate terms and by performing and non-performing categories. ​ For variable rate performing loans, the carrying amount approximates the fair value. For fixed-rate performing loans, except residential mortgage loans, the fair value is calculated by discounting scheduled cash flows through the estimated maturity using estimated market discount rates that reflect the credit and interest rate risk inherent in the loan. For performing residential mortgage loans, fair value is estimated by discounting contractual cash flows adjusted for prepayment estimates using discount rates based on secondary market sources or the primary origination market. Fixed-rate performing loans are within Level 3 of the fair value hierarchy. At September 30, 2019 and December 31, 2018, the carrying amount of fixed-rate performing loans was $1,522,399,000 and $1,515,437,000, respectively, and the estimated fair value was $1,503,049,000 and $1,469,231,000, respectively. ​ Accrued Interest ​ The carrying amounts of accrued interest approximate fair value. ​ Deposits ​ The fair value of deposits with no stated maturity, such as non-interest bearing demand deposit accounts, savings accounts and interest bearing demand deposit accounts, was equal to the amount payable on demand as of September 30, 2019 and December 31, 2018. The fair value of time deposits is based on the discounted value of contractual cashflows. The discount rate is based on currently offered rates. Time deposits are within Level 3 of the fair value hierarchy. At September 30, 2019 and December 31, 2018, the carrying amount of time deposits was $1,981,369,000 and $1,973,468,000, respectively, and the estimated fair value was $1,981,073,000 and $1,976,156,000, respectively. ​ Securities Sold Under Repurchase Agreements ​ Securities sold under repurchase agreements include short- and long-term maturities. Due to the contractual terms of the short-term instruments, the carrying amounts approximated fair value at September 30, 2019 and December 31, 2018. ​ Junior Subordinated Deferrable Interest Debentures ​ We currently have floating-rate junior subordinated deferrable interest debentures outstanding. Due to the contractual terms of the floating-rate junior subordinated deferrable interest debentures, the carrying amounts approximated fair value at September 30, 2019 and December 31, 2018. ​ Other Borrowed Funds ​ We currently have short- and long-term borrowings issued from the Federal Home Loan Bank (“FHLB”). Due to the contractual terms of the short-term borrowings, the carrying amounts approximated fair value at September 30, 2019 and December 31, 2018. The long-term borrowings outstanding at September 30, 2019 and December 31, 2018 are fixed-rate borrowings and the fair value is based on established market spreads for similar types of borrowings. The fixed rate long-term borrowings are included in Level 2 of the fair value hierarchy. At September 30, 2019 and December 31, 2018, the carrying amount of the fixed rate long-term FHLB borrowings was $436,556,000 and $436,690,000, respectively, and the estimated fair value was $463,409,000 and $436,238,000 , respectively. ​ Commitments to Extend Credit and Letters of Credit ​ Commitments to extend credit and fund letters of credit are principally at current interest rates, and, therefore, the carrying amount approximates fair value. ​ Limitations ​ Fair value estimates are made at a point in time, based on relevant market information and information about the financial instrument. These estimates do not reflect any premium or discount that could result from offering for sale at one time our entire holdings of a particular financial instrument. Because no market exists for a significant portion of our financial instruments, fair value estimates are based on judgments regarding future expected loss experience, current economic conditions, risk characteristics of various financial instruments and other factors. These estimates are subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. Changes in assumptions could significantly affect the estimates. ​ Fair value estimates are based on existing on- and off-statement of condition financial instruments without attempting to estimate the value of anticipated future business and the value of assets and liabilities that are not considered financial instruments. Other significant assets and liabilities that are not considered financial assets or liabilities include the bank premises and equipment and core deposit value. In addition, the tax ramifications related to the effect of fair value estimates have not been considered in the above estimates.

Loans

Loans	9 Months Ended
	Sep. 30, 2019
Loans
Loans	Note 3 — Loans ​ A summary of loans, by loan type at September 30, 2019 and December 31, 2018 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2019 ​ 2018 ​ ​ ​ (Dollars in Thousands) ​ Commercial, financial and agricultural $ 3,504,936 $ 3,305,124 ​ Real estate - mortgage ​ 1,151,764 ​ 1,173,101 ​ Real estate - construction ​ 2,044,410 ​ 1,886,231 ​ Consumer ​ 47,072 ​ 46,316 ​ Foreign ​ 146,960 ​ 150,517 ​ Total loans ​ $ 6,895,142 ​ $ 6,561,289 ​ ​

Allowance for Probable Loan Los

Allowance for Probable Loan Losses	9 Months Ended
	Sep. 30, 2019
Allowance for Probable Loan Losses
Allowance for Probable Loan Losses	Note 4 — Allowance for Probable Loan Losses ​ The allowance for probable loan losses primarily consists of the aggregate loan loss allowances of the Subsidiary Banks. The allowances are established through charges to operations in the form of provisions for probable loan losses. Loan losses or recoveries are charged or credited directly to the allowances. The allowance for probable loan losses of each Subsidiary Bank is maintained at a level considered appropriate by management, based on estimated probable losses in the loan portfolio. The allowance for probable loan losses is derived from the following elements: (i) allowances established on specific impaired loans, which are based on a review of the individual characteristics of each loan, including the customer’s ability to repay the loan, the underlying collateral values, and the industry in which the customer operates; (ii) allowances based on actual historical loss experience for similar types of loans in our loan portfolio; and (iii) allowances based on general economic conditions, changes in the mix of loans, company resources, border risk and credit quality indicators, among other things. All segments of the loan portfolio continue to be impacted by economic uncertainty as the economy recovers from the recent prolonged downturn. ​ Our management continually reviews the allowance for loan losses of the Subsidiary Banks using the amounts determined from the allowances established on specific impaired loans, the allowance established on quantitative historical loss percentages, and the allowance based on qualitative data to establish an appropriate amount to maintain in our allowance for loan losses. Should any of the factors considered by management in evaluating the adequacy of the allowance for probable loan losses change, our estimate of probable loan losses could also change, which could affect the level of future provisions for probable loan losses. While the calculation of the allowance for probable loan losses utilizes management’s best judgment and all information reasonably available, the adequacy of the allowance is dependent on a variety of factors beyond our control, including, among other things, the performance of the entire loan portfolio, the economy, changes in interest rates and the view of regulatory authorities towards loan classifications. ​ The loan loss provision is determined using the following methods. On a weekly basis, loan past due reports are reviewed by the credit quality committee to determine if a loan has any potential problems and if a loan should be placed on the internal classified report of the Subsidiary Banks. Additionally, the credit department of each Subsidiary Bank reviews the majority of our loans for proper internal classification purposes, regardless of whether they are past due, and segregates any loans with potential problems for further review. The credit department will discuss the potential problem loans with the servicing loan officers to determine any relevant issues that were not discovered in the evaluation. Also, an analysis of loans that is provided through examinations by regulatory authorities is considered in the review process. After the above analysis is completed, we determine if a loan should be placed on an internal classified report because of issues related to the analysis of the credit, credit documents, collateral and/or payment history. ​ A summary of the transactions in the allowance for probable loan losses by loan class is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2019 ​ ​ ​ ​ ​ ​ Domestic ​ Foreign ​ ​ ​ ​ ​ ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Real Estate: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Construction & ​ Real Estate: ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Land ​ Farmland & ​ Real Estate: ​ Residential: ​ Residential: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ Development ​ Commercial ​ Multifamily ​ First Lien ​ Junior Lien ​ Consumer ​ Foreign ​ Total ​ ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at June 30, ​ $ 11,780 ​ $ 15,273 ​ $ 17,029 ​ $ 1,849 ​ $ 3,627 ​ $ 7,312 ​ $ 488 ​ $ 845 ​ $ 58,203 ​ Losses charged to allowance ​ (3,231) ​ — ​ (468) ​ — ​ (164) ​ (214) ​ (216) ​ — ​ (4,293) ​ Recoveries credited to allowance ​ 585 ​ 4 ​ 10 ​ — ​ 3 ​ 65 ​ 5 ​ — ​ 672 ​ Net (losses) recoveries charged to allowance ​ (2,646) ​ 4 ​ (458) ​ — ​ (161) ​ (149) ​ (211) ​ — ​ (3,621) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provision charged to operations ​ 1,837 ​ 1,573 ​ 230 ​ 350 ​ 263 ​ 852 ​ 199 ​ (26) ​ 5,278 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at September 30, ​ $ 10,971 ​ $ 16,850 ​ $ 16,801 ​ $ 2,199 ​ $ 3,729 ​ $ 8,015 ​ $ 476 ​ $ 819 ​ $ 59,860 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ Domestic ​ Foreign ​ ​ ​ ​ ​ ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Real Estate: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Construction & ​ Real Estate: ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Land ​ Farmland & ​ Real Estate: ​ Residential: ​ Residential: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ Development ​ Commercial ​ Multifamily ​ First Lien ​ Junior Lien ​ Consumer ​ Foreign ​ Total ​ ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at June 30, ​ $ 16,596 ​ $ 14,703 ​ $ 18,296 ​ $ 1,574 ​ $ 3,591 ​ $ 6,793 ​ $ 450 ​ $ 850 ​ $ 62,853 ​ Losses charged to allowance ​ (6,798) ​ — ​ — ​ ​ — ​ (74) ​ (133) ​ (80) ​ (3) ​ (7,088) ​ Recoveries credited to allowance ​ 489 ​ 4 ​ 19 ​ — ​ 23 ​ 53 ​ 12 ​ 9 ​ 609 ​ Net (losses) recoveries charged to allowance ​ (6,309) ​ 4 ​ 19 ​ — ​ (51) ​ (80) ​ (68) ​ 6 ​ (6,479) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provision charged to operations ​ 3,039 ​ 397 ​ 1,050 ​ (138) ​ (354) ​ 194 ​ 57 ​ 35 ​ 4,280 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at September 30, ​ $ 13,326 ​ $ 15,104 ​ $ 19,365 ​ $ 1,436 ​ $ 3,186 ​ $ 6,907 ​ $ 439 ​ $ 891 ​ $ 60,654 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2019 ​ ​ ​ ​ ​ Domestic ​ Foreign ​ ​ ​ ​ ​ ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Real Estate: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Construction & ​ Real Estate: ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Land ​ Farmland & ​ Real Estate: ​ Residential: ​ Residential: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ Development ​ Commercial ​ Multifamily ​ First Lien ​ Junior Lien ​ Consumer ​ Foreign ​ Total ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at December 31, ​ $ 12,596 ​ $ 15,123 ​ $ 19,353 ​ $ 1,808 ​ $ 3,467 ​ $ 7,719 ​ $ 447 ​ $ 871 ​ $ 61,384 Losses charged to allowance ​ (11,011) ​ — ​ (7,347) ​ — ​ ​ (166) ​ (314) ​ (334) ​ — ​ (19,172) Recoveries credited to allowance ​ 1,631 ​ 80 ​ 308 ​ — ​ 14 ​ 222 ​ 30 ​ — ​ 2,285 Net (losses) recoveries charged to allowance ​ (9,380) ​ 80 ​ (7,039) ​ — ​ (152) ​ (92) ​ (304) ​ — ​ (16,887) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provision charged to operations ​ 7,755 ​ 1,647 ​ 4,487 ​ 391 ​ 414 ​ 388 ​ 333 ​ (52) ​ 15,363 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at September 30, ​ $ 10,971 ​ $ 16,850 ​ $ 16,801 ​ $ 2,199 ​ $ 3,729 ​ $ 8,015 ​ $ 476 ​ $ 819 ​ $ 59,860 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ Domestic ​ Foreign ​ ​ ​ ​ ​ ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Real Estate: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Construction & ​ Real Estate: ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Land ​ Farmland & ​ Real Estate: ​ Residential: ​ Residential: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ Development ​ Commercial ​ Multifamily ​ First Lien ​ Junior Lien ​ Consumer ​ Foreign ​ Total ​ ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at December 31, ​ $ 27,905 ​ $ 11,675 ​ $ 16,663 ​ $ 1,109 ​ $ 2,950 ​ $ 6,103 ​ $ 440 ​ $ 842 ​ $ 67,687 ​ Losses charged to allowance ​ (11,798) ​ ​ (1) ​ (70) ​ — ​ (118) ​ (172) ​ (262) ​ (3) ​ (12,424) ​ Recoveries credited to allowance ​ 1,520 ​ 8 ​ 229 ​ — ​ 25 ​ 348 ​ 39 ​ 10 ​ 2,179 ​ Net (losses) recoveries charged to allowance ​ (10,278) ​ 7 ​ 159 ​ — ​ (93) ​ 176 ​ (223) ​ 7 ​ (10,245) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provision charged to operations ​ (4,301) ​ 3,422 ​ 2,543 ​ 327 ​ 329 ​ 628 ​ 222 ​ 42 ​ 3,212 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at September 30, ​ $ 13,326 ​ $ 15,104 ​ $ 19,365 ​ $ 1,436 ​ $ 3,186 ​ $ 6,907 ​ $ 439 ​ $ 891 ​ $ 60,654 ​ ​ The allowance for probable loan losses is a reserve established through a provision for probable loan losses charged to expense, which represents management’s best estimate of probable loan losses when evaluating loans individually or collectively. The increase in provision for probable loan losses charged to expense and charge offs charged to the allowance for probable loan losses for the nine months ended September 30, 2019 can be primarily attributed to a relationship that is secured by multiple pieces of real property on which car dealerships are operated. The relationship began deteriorating in the fourth quarter of 2018, triggered by significant fraud by a high level insider of the car dealership resulting in the dealerships unexpectedly filing for bankruptcy and creating an exposure for potential loss since the operations of the dealerships were the source of repayment from the borrower. The relationship further deteriorated in the first quarter of 2019 after the sponsor of the court approved debtor in possession plan discontinued its role in the process and thus did not fulfill its obligation to assume full responsibility of the accrued and unpaid interest. Although the relationship is secured by real property (the dealerships’ real estate), the real property has specialized use, contributing to the potential exposure for probable loss. During the first quarter of 2019, in light of the circumstances and management’s evaluation of the relationship, the decision was made to place the relationship on impaired, non-accrual status and place a specific reserve on the relationship in the amount of $9.5 million. During the second quarter of 2019, management continued to evaluate the relationship and decided to foreclose on the underlying real estate collateral, resulting in a charge off of approximately $9,500,000 , reflected in the tables above as part of the Commercial and Commercial Real Estate: Farmland and Commercial categories. ​ The table below provides additional information on the balance of loans individually or collectively evaluated for impairment and their related allowance, by loan class as of September 30, 2019 and December 31, 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ ​ Loans Individually ​ Loans Collectively ​ ​ ​ Evaluated For ​ Evaluated For ​ ​ ​ Impairment ​ Impairment ​ ​ ​ Recorded ​ ​ ​ ​ Recorded ​ ​ ​ ​ ​ ​ Investment ​ Allowance ​ Investment ​ Allowance ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 7,412 $ 395 $ 1,288,324 $ 10,576 ​ Commercial real estate: other construction & land development ​ 1,794 ​ 116 ​ 2,042,616 ​ 16,734 ​ Commercial real estate: farmland & commercial ​ 1,740 ​ — ​ 1,965,371 ​ 16,801 ​ Commercial real estate: multifamily ​ 649 ​ — ​ 241,440 ​ 2,199 ​ Residential: first lien ​ 6,286 ​ — ​ 432,186 ​ 3,729 ​ Residential: junior lien ​ 704 ​ — ​ 712,588 ​ 8,015 ​ Consumer ​ 1,131 ​ — ​ 45,941 ​ 476 ​ Foreign ​ 273 ​ — ​ 146,687 ​ 819 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total ​ $ 19,989 ​ $ 511 ​ $ 6,875,153 ​ $ 59,349 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ ​ Loans Individually ​ Loans Collectively ​ ​ ​ Evaluated For ​ Evaluated For ​ ​ ​ Impairment ​ Impairment ​ ​ ​ Recorded ​ ​ ​ ​ Recorded ​ ​ ​ ​ ​ ​ Investment ​ Allowance ​ Investment ​ Allowance ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 9,179 $ 656 $ 1,119,790 $ 11,940 ​ Commercial real estate: other construction & land development ​ 2,092 ​ 116 ​ 1,884,139 ​ 15,007 ​ Commercial real estate: farmland & commercial ​ 3,509 ​ — ​ 1,946,389 ​ 19,353 ​ Commercial real estate: multifamily ​ 507 ​ — ​ 225,750 ​ 1,808 ​ Residential: first lien ​ 6,244 ​ — ​ 439,556 ​ 3,467 ​ Residential: junior lien ​ 901 ​ — ​ 726,400 ​ 7,719 ​ Consumer ​ 1,175 ​ — ​ 45,141 ​ 447 ​ Foreign ​ 293 ​ — ​ 150,224 ​ 871 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total ​ $ 23,900 ​ $ 772 ​ $ 6,537,389 ​ $ 60,612 ​ ​ The table below provides additional information on loans accounted for on a non-accrual basis by loan class at September 30, 2019 and December 31, 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ December 31, 2018 ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ Commercial $ 7,379 $ 9,143 ​ Commercial real estate: other construction & land development ​ 1,794 ​ 2,092 ​ Commercial real estate: farmland & commercial ​ 1,740 ​ 3,509 ​ Commercial real estate: multifamily ​ 649 ​ 507 ​ Residential: first lien ​ 583 ​ 347 ​ Residential: junior lien ​ — ​ 171 ​ Consumer ​ 5 ​ 22 ​ Total non-accrual loans ​ $ 12,150 ​ $ 15,791 ​ ​ Impaired loans are those loans where it is probable that all amounts due according to contractual terms of the loan agreement will not be collected. We have identified these loans through our normal loan review procedures. Impaired loans are measured based on (i) the present value of expected future cash flows discounted at the loan’s effective interest rate; (ii) the loan’s observable market price; or (iii) the fair value of the collateral if the loan is collateral dependent. Substantially all of our impaired loans are measured at the fair value of the collateral. In limited cases, we may use other methods to determine the level of impairment of a loan if such loan is not collateral dependent. ​ The following tables detail key information regarding our impaired loans by loan class at September 30, 2019 and December 31, 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quarter to Date ​ Year to Date ​ ​ ​ ​ ​ Unpaid ​ ​ ​ ​ Average ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Recorded ​ Principal ​ Related ​ Recorded ​ Interest ​ Recorded ​ Interest ​ ​ Investment ​ Balance ​ Allowance ​ Investment ​ Recognized ​ Investment ​ Recognized ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ Loans with Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ $ 598 ​ $ 621 ​ $ 395 ​ $ 602 ​ $ — ​ $ 616 ​ $ — Commercial real estate: other construction & land development ​ ​ 128 ​ ​ 169 ​ ​ 116 ​ 129 ​ — ​ ​ 132 ​ ​ — Total impaired loans with related allowance ​ $ 726 ​ $ 790 ​ $ 511 ​ $ 731 ​ $ — ​ $ 748 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ Quarter to Date ​ Year to Date ​ ​ ​ ​ ​ Unpaid ​ Average ​ ​ Average ​ ​ ​ ​ Recorded ​ Principal ​ Recorded ​ Interest ​ Recorded ​ Interest ​ ​ Investment ​ Balance ​ Investment ​ Recognized ​ Investment ​ Recognized ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ Loans with No Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ $ 6,814 ​ $ 6,963 ​ $ 8,002 ​ $ 1 ​ $ 17,945 ​ $ 2 Commercial real estate: other construction & land development ​ 1,666 ​ 1,953 ​ 1,674 ​ — ​ 1,767 ​ — Commercial real estate: farmland & commercial ​ 1,740 ​ 2,368 ​ 3,222 ​ — ​ 22,389 ​ — Commercial real estate: multifamily ​ 649 ​ 684 ​ 653 ​ — ​ 656 ​ — Residential: first lien ​ 6,286 ​ 6,400 ​ 6,427 ​ 78 ​ 6,698 ​ 231 Residential: junior lien ​ 704 ​ 708 ​ 914 ​ 10 ​ 1,028 ​ 32 Consumer ​ 1,131 ​ 1,131 ​ 1,131 ​ — ​ ​ 1,088 ​ — Foreign ​ 273 ​ 273 ​ 274 ​ 3 ​ 281 ​ 9 Total impaired loans with no related allowance ​ $ 19,263 ​ $ 20,480 ​ $ 22,297 ​ $ 92 ​ $ 51,852 ​ $ 274 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ ​ ​ ​ Unpaid ​ ​ ​ ​ Average ​ ​ ​ ​ ​ ​ Recorded ​ Principal ​ Related ​ Recorded ​ Interest ​ ​ ​ Investment ​ Balance ​ Allowance ​ Investment ​ Recognized ​ ​ ​ (Dollars in Thousands) Loans with Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ $ 1,563 ​ $ 2,161 ​ $ 656 ​ $ 1,741 ​ $ — ​ Commercial real estate: other construction & land development ​ ​ 135 ​ ​ 169 ​ ​ 116 ​ 141 ​ — ​ Total impaired loans with related allowance ​ $ 1,698 ​ $ 2,330 ​ $ 772 ​ $ 1,882 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ ​ ​ ​ Unpaid Average ​ ​ ​ ​ ​ ​ Recorded ​ Principal Recorded ​ Interest ​ ​ ​ Investment ​ Balance Investment ​ Recognized ​ ​ ​ (Dollars in Thousands) Loans with No Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 7,616 ​ $ 7,730 ​ $ 16,194 ​ $ 3 ​ Commercial real estate: other construction & land development ​ 1,957 ​ 2,205 ​ 2,151 ​ — ​ Commercial real estate: farmland & commercial ​ 3,509 ​ 4,031 ​ 36,632 ​ — ​ Commercial real estate: multifamily ​ 507 ​ 538 ​ 565 ​ — ​ Residential: first lien ​ 6,244 ​ 6,386 ​ 7,136 ​ 305 ​ Residential: junior lien ​ 901 ​ 911 ​ 976 ​ 44 ​ Consumer ​ 1,175 ​ 1,190 ​ 1,211 ​ 2 ​ Foreign ​ 293 ​ 293 ​ 327 ​ 14 ​ Total impaired loans with no related allowance ​ $ 22,202 ​ $ 23,284 ​ $ 65,192 ​ $ 368 ​ ​ ​ ​ The following table details key information regarding our impaired loans by loan class at September 30, 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2018 ​ ​ Quarter to Date ​ ​ Year to Date ​ ​ Average ​ ​ ​ Average ​ ​ ​ ​ ​ Recorded ​ Interest ​ Recorded ​ Interest ​ ​ Investment ​ Recognized ​ Investment ​ Recognized ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ Loans with Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ $ 1,620 ​ $ — ​ $ 1,794 ​ $ — Commercial real estate: other construction & land development ​ 139 ​ — ​ 142 ​ — Total impaired loans with related allowance ​ $ 1,759 ​ $ — ​ $ 1,936 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2018 ​ ​ Quarter to Date ​ Year to Date ​ ​ Average ​ ​ Average ​ ​ ​ ​ ​ Recorded ​ Interest Recorded ​ Interest ​ ​ Investment ​ Recognized Investment ​ Recognized ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ Loans with No Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 15,758 ​ $ — ​ $ 16,464 ​ $ 2 Commercial real estate: other construction & land development ​ 1,994 ​ — ​ 2,203 ​ — Commercial real estate: farmland & commercial ​ 5,986 ​ — ​ 36,633 ​ — Commercial real estate: multifamily ​ 590 ​ — ​ 575 ​ — Residential: first lien ​ 6,362 ​ 76 ​ 6,929 ​ 228 Residential: junior lien ​ 743 ​ 11 ​ 807 ​ 33 Consumer ​ 1,187 ​ 1 ​ 1,192 ​ 2 Foreign ​ 318 ​ 4 ​ 331 ​ 11 Total impaired loans with no related allowance ​ $ 32,938 ​ $ 92 ​ $ 65,134 ​ $ 276 ​ A portion of the impaired loans have adequate collateral and credit enhancements not requiring a related allowance for loan loss. Management recognizes the risks associated with these impaired loans, however, management is confident our loss exposure regarding these credits will be significantly reduced due to our long-standing practices that encompass the following principles: (i) the financial strength of the borrower, including strong earnings, a high net worth, significant liquidity and an acceptable debt to worth ratio, (ii) managerial and business competence, (iii) the ability to repay, (iv) for a new business, projected cash flows, (v) loan to value, (vi) in the case of a secondary guarantor, a guarantor financial statement, and (vii) financial and/or other character references. Management’s decision to place loans in this category does not necessarily mean that we will experience significant losses from these loans or significant increases in impaired loans from these levels. ​ The following table details loans accounted for as “troubled debt restructuring,” segregated by loan class. Loans accounted for as troubled debt restructuring are included in impaired loans. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 December 31, 2018 ​ ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ Commercial $ 33 $ 35 ​ Residential: first lien ​ ​ 5,703 ​ ​ 5,947 ​ Residential: junior lien ​ ​ 704 ​ ​ 730 ​ Consumer ​ ​ 1,126 ​ ​ 1,153 ​ Foreign ​ ​ 273 ​ ​ 293 ​ ​ ​ ​ ​ ​ ​ ​ ​ Total troubled debt restructuring ​ $ 7,839 ​ $ 8,158 ​ ​ The Subsidiary Banks charge-off that portion of any loan which management considers to represent a loss as well as that portion of any other loan which is classified as a “loss” by bank examiners. Commercial and industrial or real estate loans are generally considered by management to represent a loss, in whole or part, when an exposure beyond any collateral coverage is apparent and when no further collection of the loss portion is anticipated based on the borrower’s financial condition and general economic conditions in the borrower’s industry. Generally, unsecured consumer loans are charged-off when 90 days past due. ​ While our management believes that it is generally able to identify borrowers with financial problems reasonably early and to monitor credit extended to such borrowers carefully, there is no precise method of predicting loan losses. The determination that a loan is likely to be uncollectible and that it should be wholly or partially charged-off as a loss is an exercise of judgment. Similarly, the determination of the adequacy of the allowance for probable loan losses can be made only on a subjective basis. It is the judgment of our management that the allowance for probable loan losses at September 30, 2019 was adequate to absorb probable losses from loans in the portfolio at that date. ​ The following tables present information regarding the aging of past due loans by loan class at September 30, 2019 and December 31, 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 90 Days or ​ Total ​ ​ ​ ​ ​ ​ ​ ​ ​ 30 - 59 ​ 60 - 89 ​ 90 Days or ​ greater & ​ Past ​ ​ ​ ​ Total ​ ​ ​ Days ​ Days ​ Greater ​ still accruing ​ Due ​ Current ​ Portfolio ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 3,493 $ 902 $ 7,408 $ 1,477 $ 11,803 $ 1,283,933 $ 1,295,736 ​ Commercial real estate: other construction & land development ​ 8,977 ​ 18,504 ​ 1,100 ​ 286 ​ 28,581 ​ 2,015,829 ​ 2,044,410 ​ Commercial real estate: farmland & commercial ​ 3,210 ​ 56,125 ​ 1,270 ​ 737 ​ 60,605 ​ 1,906,506 ​ 1,967,111 ​ Commercial real estate: multifamily ​ 24 ​ 290 ​ 1,265 ​ 764 ​ 1,579 ​ 240,510 ​ 242,089 ​ Residential: first lien ​ 2,961 ​ 1,169 ​ 3,303 ​ 2,930 ​ 7,433 ​ 431,039 ​ 438,472 ​ Residential: junior lien ​ 1,316 ​ 305 ​ 1,216 ​ 1,216 ​ 2,837 ​ 710,455 ​ 713,292 ​ Consumer ​ 770 ​ 128 ​ 69 ​ 69 ​ 967 ​ 46,105 ​ 47,072 ​ Foreign ​ 2,119 ​ 490 ​ 147 ​ 147 ​ 2,756 ​ 144,204 ​ 146,960 ​ Total past due loans ​ $ 22,870 ​ $ 77,913 ​ $ 15,778 ​ $ 7,626 ​ $ 116,561 ​ $ 6,778,581 ​ $ 6,895,142 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 90 Days or ​ Total ​ ​ ​ ​ ​ ​ ​ ​ ​ 30 - 59 ​ 60 - 89 ​ 90 Days or ​ greater & ​ Past ​ ​ ​ ​ Total ​ ​ ​ Days ​ Days ​ Greater ​ still accruing ​ Due ​ Current ​ Portfolio ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ $ 4,651 $ 1,089 $ 19,851 $ 10,890 $ 25,591 $ 1,103,378 $ 1,128,969 ​ Commercial real estate: other construction & land development ​ 727 ​ 1,707 ​ 922 ​ 16 ​ 3,356 ​ 1,882,875 ​ 1,886,231 ​ Commercial real estate: farmland & commercial ​ 2,928 ​ 784 ​ 27,239 ​ 24,910 ​ 30,951 ​ 1,918,947 ​ 1,949,898 ​ Commercial real estate: multifamily ​ 927 ​ — ​ 578 ​ 71 ​ 1,505 ​ 224,752 ​ 226,257 ​ Residential: first lien ​ 3,998 ​ 1,677 ​ 3,362 ​ 3,079 ​ 9,037 ​ 436,763 ​ 445,800 ​ Residential: junior lien ​ 1,155 ​ 618 ​ 1,108 ​ 937 ​ 2,881 ​ 724,420 ​ 727,301 ​ Consumer ​ 486 ​ 19 ​ 45 ​ 32 ​ 550 ​ 45,766 ​ 46,316 ​ Foreign ​ 1,106 ​ 117 ​ 739 ​ 739 ​ 1,962 ​ 148,555 ​ 150,517 ​ Total past due loans ​ $ 15,978 ​ $ 6,011 ​ $ 53,844 ​ $ 40,674 ​ $ 75,833 ​ $ 6,485,456 ​ $ 6,561,289 ​ ​ The increase in loans past due 60 – 89 days at September 30, 2019 compared to December 31, 2018 can be primarily attributed to a loan relationship secured by real property on which a commercial office building is being constructed and a relationship secured by real estate on which private education centers are operated. The decrease in the 90 days or greater and still accruing loans at September 30, 2019 compared to December 31, 2018 can be primarily attributed to the previously discussed relationship secured by real property on which car dealerships are operated and the foreclosure of the underlying real estate assets securing the relationship in the second quarter of 2019. ​ Our internal classified report is segregated into the following categories: (i) “Special Review Credits,” (ii) “Watch List-Pass Credits,” and (iii) “Watch List-Substandard Credits.” The loans placed in the “Special Review Credits” category reflect management’s opinion that the loans reflect potential weakness which requires monitoring on a more frequent basis. The “Special Review Credits” are reviewed and discussed on a regular basis with the credit department and the lending staff to determine if a change in category is warranted. The loans placed in the “Watch List-Pass Credits” category reflect our opinion that the credit contains weaknesses which represent a greater degree of risk, which warrant “extra attention.” The “Watch List-Pass Credits” are reviewed and discussed on a regular basis with the credit department and the lending staff to determine if a change in category is warranted. The loans placed in the “Watch List-Substandard Credits” classification are considered to be potentially inadequately protected by the current sound worth and debt service capacity of the borrower or of any pledged collateral. These credit obligations, even if apparently protected by collateral value, have shown defined weaknesses related to adverse financial, managerial, economic, market or political conditions which may jeopardize repayment of principal and interest. Furthermore, there is the possibility that we could sustain some future loss if such weaknesses are not corrected. For loans that are classified as impaired, management evaluates these credits in accordance with the provisions of ASC 310-10, “Receivables,” and, if deemed necessary, a specific reserve is allocated to the credit. The specific reserve allocated under ASC 310-10 is based on (i) the present value of expected future cash flows discounted at the loan’s effective interest rate; (ii) the loan’s observable market price; or (iii) the fair value of the collateral if the loan is collateral dependent. Substantially all of our loans evaluated as impaired under ASC 310-10 are measured using the fair value of collateral method. In limited cases, we may use other methods to determine the specific reserve of a loan under ASC 310-10 if such loan is not collateral dependent. ​ The allowance based on historical loss experience on our remaining loan portfolio, which includes the “Special Review Credits,” “Watch List - Pass Credits,” and “Watch List - Substandard Credits” is determined by segregating the remaining loan portfolio into certain categories such as commercial loans, installment loans, international loans, loan concentrations and overdrafts. Installment loans are then further segregated by number of days past due. A historical loss percentage, adjusted for (i) management’s evaluation of changes in lending policies and procedures, (ii) current economic conditions in the market area we serve, (iii) other risk factors, (iv) the effectiveness of the internal loan review function, (v) changes in loan portfolios, and (vi) the composition and concentration of credit volume is applied to each category. Each category is then added together to determine the allowance allocated under ASC 450-20. ​ A summary of the loan portfolio by credit quality indicator by loan class at September 30, 2019 and December 31, 2018 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ ​ ​ ​ ​ Special ​ Watch ​ Watch List— ​ Watch List— ​ ​ ​ Pass ​ Review ​ List—Pass ​ Substandard ​ Impaired ​ ​ ​ ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 1,228,895 $ 19 $ 957 $ 58,453 $ 7,412 ​ Commercial real estate: other construction & land development ​ 1,948,752 ​ — ​ 37,566 ​ 56,298 ​ 1,794 ​ Commercial real estate: farmland & commercial ​ 1,771,180 ​ 7,975 ​ 34,067 ​ 152,149 ​ 1,740 ​ Commercial real estate: multifamily ​ 240,535 ​ — ​ — ​ 905 ​ 649 ​ Residential: first lien ​ 430,825 ​ — ​ 143 ​ 1,218 ​ 6,286 ​ Residential: junior lien ​ 711,747 ​ — ​ 841 ​ — ​ 704 ​ Consumer ​ 45,941 ​ — ​ — ​ — ​ 1,131 ​ Foreign ​ 146,550 ​ — ​ — ​ 137 ​ 273 ​ Total ​ $ 6,524,425 ​ $ 7,994 ​ $ 73,574 ​ $ 269,160 ​ $ 19,989 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ ​ ​ ​ ​ Special ​ Watch ​ Watch List— ​ Watch List— ​ ​ ​ Pass ​ Review ​ List—Pass ​ Substandard ​ Impaired ​ ​ ​ ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 998,625 $ 441 $ 44,544 $ 76,180 $ 9,179 ​ Commercial real estate: other construction & land development ​ 1,817,098 ​ 1,648 ​ 9,055 ​ 56,338 ​ 2,092 ​ Commercial real estate: farmland & commercial ​ 1,726,711 ​ 62,046 ​ 38,373 ​ 119,259 ​ 3,509 ​ Commercial real estate: multifamily ​ 224,823 ​ — ​ — ​ 927 ​ 507 ​ Residential: first lien ​ 438,773 ​ — ​ 142 ​ 641 ​ 6,244 ​ Residential: junior lien ​ 725,538 ​ — ​ 862 ​ — ​ 901 ​ Consumer ​ 45,141 ​ — ​ — ​ — ​ 1,175 ​ Foreign ​ 150,224 ​ — ​ — ​ — ​ 293 ​ Total ​ $ 6,126,933 ​ $ 64,135 ​ $ 92,976 ​ $ 253,345 ​ $ 23,900 ​ ​ The decrease in Special Review credits at September 30, 2019 compared to December 31, 2018 can be primarily attributed to a relationship secured by real property on which education centers are operated being downgraded to Watch-List Substandard. The decrease in Watch List – Pass credits at September 30, 2019 from December 31, 2018 can be primarily attributed to the reclassification of a relationship secured by oil and gas properties to Pass offset by the addition of relationships secured by real estate on which commercial buildings are being constructed. The increase in Watch List- Substandard credits at September 30, 2019 compared to December 31, 2018 can be primarily attributed to the previously mentioned relationship secured by real estate on which education centers are operated offset by the foreclosure of the underlying real estate assets in the previously discussed relationship on which car dealerships were operated and a pay down on a relationship secured primarily by aircraft.

Stock Options

Stock Options	9 Months Ended
	Sep. 30, 2019
Stock Options
Stock Options	Note 5 — Stock Options ​ On April 5, 2012, the Board of Directors adopted the 2012 International Bancshares Corporation Stock Option Plan (the “2012 Plan”). There are 800,000 shares of common stock available for stock option grants under the 2012 Plan, which may be qualified incentive stock options (“ISOs”) or non-qualified stock options. Options granted may be exercisable for a period of up to 10 years from the date of grant, excluding ISOs granted to 10% shareholders, which may be exercisable for a period of up to only five years . As of September 30, 2019, 27,276 shares were available for future grants under the 2012 Plan. ​ A summary of option activity under the stock option plan for the nine months ended September 30, 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Weighted ​ average ​ ​ ​ ​ ​ ​ ​ ​ average ​ remaining ​ Aggregate ​ ​ ​ Number of ​ exercise ​ contractual ​ intrinsic ​ ​ ​ options ​ price ​ term (years) ​ value ($) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in Thousands) ​ Options outstanding at December 31, 2018 788,977 ​ $ 25.91 ​ ​ ​ ​ ​ ​ Plus: Options granted 16,500 ​ 35.34 ​ ​ ​ ​ ​ ​ Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options exercised 87,663 ​ 17.30 ​ ​ ​ ​ ​ ​ Options expired — ​ — ​ ​ ​ ​ ​ ​ Options forfeited 34,576 ​ 26.95 ​ ​ ​ ​ ​ ​ Options outstanding at September 30, 2019 683,238 ​ 27.19 5.86 ​ $ 7,809 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options fully vested and exercisable at September 30, 2019 322,772 ​ $ 22.08 4.62 ​ $ 5,339 ​ ​ Stock-based compensation expense included in the consolidated statements of income for the three and nine months ended September 30, 2019 is $240,000 and $744,000 , respectively. Stock-based compensation expense included in the consolidated statements of income for the three and nine months ended September 30, 2018 was $285,000 and $755,000 , respectively. As of September 30, 2019, there was approximately $2,158,000 of total unrecognized stock-based compensation cost related to non-vested options granted under our plans that will be recognized over a weighted average period of 1.9 years.

Investment Securities and Equit

Investment Securities and Equity Securities with Readily Determinable Fair Values	9 Months Ended
	Sep. 30, 2019
Investment Securities and Equity Securities with Readily Determinable Fair Values
Investment Securities and Equity Securities with Readily Determinable Fair Values	Note 6 — Investment Securities and Equity Securities with Readily Determinable Fair Values ​ We classify debt securities into one of three categories: held-to maturity, available-for-sale, or trading. Such debt securities are reassessed for appropriate classification at each reporting date. Securities classified as “held-to-maturity” are carried at amortized cost for financial statement reporting, while securities classified as “available-for-sale” and “trading” are carried at their fair value. Unrealized holding gains and losses are included in net income for those securities classified as “trading,” while unrealized holding gains and losses related to those securities classified as “available-for-sale” are excluded from net income and reported net of tax as other comprehensive income (loss) and accumulated other comprehensive income (loss) until realized, or in the case of losses, when deemed other than temporary. In accordance with the provisions of ASU 2016-01, which we adopted on January 1, 2018, unrealized holding gains and losses related to equity securities with readily determinable fair values are included in net income. ​ The amortized cost and estimated fair value by type of investment security at September 30, 2019 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Held to Maturity ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ unrealized ​ unrealized ​ Estimated ​ Carrying ​ ​ ​ cost ​ gains ​ losses ​ fair value ​ value ​ ​ ​ (Dollars in Thousands) ​ Other securities $ 2,400 $ — $ — $ 2,400 $ 2,400 ​ Total investment securities ​ $ 2,400 ​ $ — ​ $ — ​ $ 2,400 ​ $ 2,400 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available for Sale Debt Securities ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ unrealized ​ unrealized ​ Estimated ​ Carrying ​ ​ ​ cost ​ gains ​ losses ​ fair value ​ value (1) ​ ​ ​ (Dollars in Thousands) ​ Residential mortgage-backed securities $ 3,095,049 $ 19,558 $ (17,197) $ 3,097,410 $ 3,097,410 ​ Obligations of states and political subdivisions ​ 92,199 ​ 3,263 ​ — ​ 95,462 ​ 95,462 ​ Total investment securities ​ $ 3,187,248 ​ $ 22,821 ​ $ (17,197) ​ $ 3,192,872 ​ $ 3,192,872 ​ (1) Included in the carrying value of residential mortgage-backed securities are $514,847 of mortgage-backed securities issued by Ginnie Mae and $2,582,563 of mortgage-backed securities issued by Fannie Mae and Freddie Mac. ​ The amortized cost and estimated fair value by type of investment security at December 31, 2018 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Held to Maturity ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ unrealized ​ unrealized ​ Estimated ​ Carrying ​ ​ ​ cost ​ gains ​ losses ​ fair value ​ value ​ ​ ​ (Dollars in Thousands) ​ Other securities $ 1,200 $ — $ — $ 1,200 $ 1,200 ​ Total investment securities ​ $ 1,200 ​ $ — ​ $ — ​ $ 1,200 ​ $ 1,200 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available for Sale ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ Estimated ​ ​ ​ ​ ​ ​ Amortized ​ unrealized ​ unrealized ​ fair ​ Carrying ​ ​ ​ cost ​ gains ​ losses ​ value ​ value (1) ​ ​ ​ (Dollars in Thousands) ​ Residential mortgage-backed securities $ 3,295,366 $ 6,813 $ (79,169) $ 3,223,010 $ 3,223,010 ​ Obligations of states and political subdivisions ​ 185,799 ​ 2,646 ​ (105) ​ 188,340 ​ 188,340 ​ Total investment securities ​ $ 3,481,165 ​ $ 9,459 ​ $ (79,274) ​ $ 3,411,350 ​ $ 3,411,350 ​ (1) Included in the carrying value of residential mortgage-backed securities are $501,293 of mortgage-backed securities issued by Ginnie Mae and $2,721,717 of mortgage-backed securities issued by Fannie Mae and Freddie. ​ ​ The amortized cost and estimated fair value of investment securities at September 30, 2019, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to prepay obligations with or without prepayment penalties. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Held to Maturity ​ Available for Sale ​ ​ ​ Amortized ​ Estimated ​ Amortized ​ Estimated ​ ​ ​ Cost ​ fair value ​ Cost ​ fair value ​ ​ ​ (Dollars in Thousands) ​ Due in one year or less $ 1,075 $ 1,075 $ — $ — ​ Due after one year through five years ​ 1,325 ​ 1,325 ​ — ​ — ​ Due after five years through ten years ​ — ​ — ​ 2,243 ​ 2,267 ​ Due after ten years ​ — ​ — ​ 89,956 ​ 93,195 ​ Residential mortgage-backed securities ​ — ​ — ​ 3,095,049 ​ 3,097,410 ​ Total investment securities ​ $ 2,400 ​ $ 2,400 ​ $ 3,187,248 ​ $ 3,192,872 ​ ​ Residential mortgage-backed securities are securities primarily issued by the Federal Home Loan Mortgage Corporation (“Freddie Mac”), Federal National Mortgage Association (“Fannie Mae”), or the Government National Mortgage Association (“Ginnie Mae”). Investments in residential mortgage-backed securities issued by Ginnie Mae are fully guaranteed by the U.S. Government. Investments in residential mortgage-backed securities issued by Freddie Mac and Fannie Mae are not fully guaranteed by the U.S. Government, however, we believe that the quality of the bonds is similar to other AAA rated bonds with limited credit risk, particularly given the placement of Fannie Mae and Freddie Mac into conservatorship by the federal government in early September 2008 and because securities issued by others that are collateralized by residential mortgage-backed securities issued by Fannie Mae or Freddie Mac are rated consistently as AAA rated securities. ​ The amortized cost and fair value of available-for-sale debt investment securities pledged to qualify for fiduciary powers, to secure public monies as required by law, repurchase agreements and short-term fixed borrowings was $1,143,623,000 and $1,142,310,000, respectively, at September 30, 2019. ​ Proceeds from the sale and calls of debt securities available-for-sale were $32,285,000 and $92,980,000 for the three and nine months ended September 30, 2019, which included $0 and $0 of mortgage-backed securities, respectively. Gross gains of $1 and $4 and gross losses of $3 and $16 were realized on the sales and calls for the three and nine months ended September 30, 2019, respectively. Proceeds from the sale and call of debt securities available-for-sale were $19,530,000 and $37,675,000 for the three and nine months ended September 30, 2018, which included $0 and $0 of mortgage-backed securities, respectively. Gross gains of $2 and $3 and gross losses of $0 and $0 were realized on the sales and calls for the three and nine months ended September 30, 2018, respectively. ​ Gross unrealized losses on debt investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual debt securities have been in a continuous unrealized loss position at September 30, 2019, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less than 12 months ​ 12 months or more ​ Total ​ ​ ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized ​ ​ ​ Fair Value ​ Losses ​ Fair Value ​ Losses ​ Fair Value ​ Losses ​ ​ ​ (Dollars in Thousands) ​ Available for sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Residential mortgage-backed securities $ 209,786 $ (600) $ 1,593,578 $ (16,597) $ 1,803,364 $ (17,197) ​ ​ ​ $ 209,786 ​ $ (600) ​ $ 1,593,578 ​ $ (16,597) ​ $ 1,803,364 ​ $ (17,197) ​ ​ Gross unrealized losses on investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2018 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less than 12 months ​ 12 months or more ​ Total ​ ​ ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized ​ ​ ​ Fair Value ​ Losses ​ Fair Value ​ Losses ​ Fair Value ​ Losses ​ ​ ​ (Dollars in Thousands) ​ Available for sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Residential mortgage-backed securities $ 208,384 $ (2,124) $ 2,537,181 $ (77,045) $ 2,745,565 $ (79,169) ​ Obligations of states and political subdivisions ​ 12,756 ​ (99) ​ 512 ​ (6) ​ 13,268 ​ (105) ​ ​ ​ $ 221,140 ​ $ (2,223) ​ $ 2,537,693 ​ $ (77,051) ​ $ 2,758,833 ​ $ (79,274) ​ ​ The unrealized losses on investments in residential mortgage-backed securities are primarily caused by changes in market interest rates. Residential mortgage-backed securities are primarily securities issued by Freddie Mac, Fannie Mae and Ginnie Mae. The contractual cash obligations of the securities issued by Ginnie Mae are fully guaranteed by the U.S. Government. The contractual cash obligations of the securities issued by Freddie Mac and Fannie Mae are not fully guaranteed by the U.S. Government; however, we believe that the quality of the bonds is similar to other AAA rated bonds with limited credit risk, particularly given the placement of Fannie Mae and Freddie Mac into conservatorship by the federal government in early September 2008, and because securities issued by others that are collateralized by residential mortgage-backed securities issued by Fannie Mae and Freddie Mac are rated consistently as AAA rated securities. The decrease in fair value on residential mortgage-backed securities issued by Freddie Mac, Fannie Mae and Ginnie Mae is due to market interest rates. We have no intent to sell and will more than likely not be required to sell before a market price recovery or maturity of the securities; therefore, it is our conclusion that the investments in residential mortgage-backed securities issued by Freddie Mac, Fannie Mae and Ginnie Mae are not considered other-than-temporarily impaired. ​ Equity securities with readily determinable fair values consist primarily of Community Reinvestment Act funds. At September 30, 2019 and December 31, 2018, the balance in equity securities with readily determinable fair values recorded at fair value were $6,172,000 and $5,937,000 , respectively. Prior to January 1, 2018, the equity securities were included in available-for-sale securities, with the related unrealized gain or loss recorded as a component of other comprehensive income. The following is a summary of unrealized and realized gains and losses recognized in net income on equity securities during the three and nine months ended September 30, 2019 and the three and nine months ended September 30, 2018: ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ September 30, 2019 ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ Net gains recognized during the period on equity securities $ ​ 45 Less: Net gains and (losses) recognized during the period on equity securities sold during the period ​ ​ — ​ ​ ​ ​ ​ Unrealized gains recognized during the reporting period on equity securities still held at the reporting date ​ $ ​ 45 ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ September 30, 2018 ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ Net losses recognized during the period on equity securities $ ​ (62) Less: Net gains and (losses) recognized during the period on equity securities sold during the period ​ ​ (771) ​ ​ ​ ​ ​ Unrealized gains recognized during the reporting period on equity securities still held at the reporting date ​ $ ​ 709 ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended ​ ​ September 30, 2019 ​ ​ (Dollars in Thousands) ​ ​ ​ Net gains recognized during the period on equity securities $ ​ 235 Less: Net gains and (losses) recognized during the period on equity securities sold during the period ​ ​ — ​ ​ ​ ​ ​ Unrealized gains recognized during the reporting period on equity securities still held at the reporting date ​ $ ​ 235 ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended ​ ​ September 30, 2018 ​ ​ (Dollars in Thousands) ​ ​ ​ Net losses recognized during the period on equity securities $ ​ (1,083) Less: Net gains and (losses) recognized during the period on equity securities sold during the period ​ ​ (771) ​ ​ ​ ​ ​ Unrealized losses recognized during the reporting period on equity securities still held at the reporting date ​ $ ​ (312) ​

Other Borrowed Funds

Other Borrowed Funds	9 Months Ended
	Sep. 30, 2019
Other Borrowed Funds
Other Borrowed Funds	Note 7 — Other Borrowed Funds ​ Other borrowed funds include FHLB borrowings, which are short-term and long-term borrowings issued by the FHLB of Dallas and the FHLB of Topeka at the market price offered at the time of funding. These borrowings are secured by residential mortgage-backed investment securities and a portion of our loan portfolio. At September 30, 2019, other borrowed funds totaled $456,556,000, a decrease of 35.3% from $705,665,000 at December 31, 2018. The decrease in borrowings can be primarily attributed to decreased liquidity needs to fund operations and loan activity. ​

Junior Subordinated Interest De

Junior Subordinated Interest Deferrable Debentures	9 Months Ended
	Sep. 30, 2019
Junior Subordinated Interest Deferrable Debentures
Junior Subordinated Interest Deferrable Debentures	Note 8 — Junior Subordinated Interest Deferrable Debentures ​ As of September 30, 2019, we have five statutory business trusts under the laws of the State of Delaware, for the purpose of issuing trust preferred securities. The five statutory business trusts we formed (the “Trusts”) have each issued Capital and Common Securities and invested the proceeds thereof in an equivalent amount of junior subordinated debentures (“Debentures”) that we issued. As of September 30, 2019 and December 31, 2018, the principal amount of Debentures outstanding totaled $134,642,000 and $160,416,000, respectively. On May 7, 2019, after receiving the required regulatory approvals, we redeemed the full of Junior Subordinated Deferrable Interest Debentures related to IB Capital Trust VI. ​ The Debentures are subordinated and junior in right of payment to all present and future senior indebtedness (as defined in the respective Indentures) and are pari passu terms of the Debentures are the same as the distribution rate and payment terms of the respective issues of Capital and Common Securities issued by the Trusts. We have fully and unconditionally guaranteed the obligations of each of the Trusts with respect to the Capital and Common Securities. We have the right, unless an Event of Default (as defined in the Indentures) has occurred and is continuing, to defer payment of interest on the Debentures for up to twenty consecutive quarterly periods on Trusts VIII, IX, X, XI and XII. If interest payments on any of the Debentures are deferred, distributions on both the Capital and Common Securities related to that Debenture would also be deferred. The redemption prior to maturity of any of the Debentures may require the prior approval of the Federal Reserve and/or other regulatory bodies. ​ For financial reporting purposes, the Trusts are treated as our investments and not consolidated in our consolidated financial statements. Although the Capital and Common Securities issued by each of the Trusts are not included as a component of shareholders’ equity on the consolidated statement of condition, the Capital and Common Securities are treated as capital for regulatory purposes. Specifically, under applicable regulatory guidelines, the Capital and Common Securities issued by the Trusts qualify as Tier 1 capital up to a maximum of 25 % of Tier 1 capital on an aggregate basis. Any amount that exceeds the 25 % threshold would qualify as Tier 2 capital. At September 30, 2019 and December 31, 2018, the total $134,642,000 and $160,416,000 of the Capital and Common Securities outstanding qualified as Tier 1 capital. ​ The following table illustrates key information about each of the Capital and Common Securities and their interest rate at September 30, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Junior ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subordinated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferrable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest ​ Repricing ​ Interest ​ Interest ​ ​ ​ Optional ​ ​ ​ Debentures ​ Frequency ​ Rate ​ Rate Index(1) ​ Maturity Date ​ Redemption Date (1) ​ ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trust VIII ​ $ 25,774 Quarterly 5.35 % LIBOR + 3.05 October 2033 October 2008 ​ Trust IX ​ 41,238 Quarterly 3.94 % LIBOR + 1.62 October 2036 October 2011 ​ Trust X ​ 21,021 Quarterly 3.90 % LIBOR + 1.65 February 2037 February 2012 ​ Trust XI ​ 25,990 Quarterly 3.94 % LIBOR + 1.62 July 2037 July 2012 ​ Trust XII ​ 20,619 Quarterly 3.58 % LIBOR + 1.45 September 2037 September 2012 ​ ​ ​ $ 134,642 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The Capital and Common Securities may be redeemed in whole or in part on any interest payment date after the Optional Redemption Date.

Common Stock and Dividends

Common Stock and Dividends	9 Months Ended
	Sep. 30, 2019
Common Stock and Dividends
Common Stock and Dividends	Note 9 — Common Stock and Dividends ​ We paid cash dividends of $0.50 and $0.55 per share on April 15 and October 15, 2019 to record holders of our common stock on April 1 and September 30, 2019, respectively. We paid cash dividends of $0.33 and $0.42 per share on April 16 and October 16, 2018 to record holders of our common stock on April 2 and October 9, 2018, respectively. ​ In April 2009, the Board of Directors re-established a formal stock repurchase program that authorized the repurchase of up to $40 million of common stock within the following 12 months . Annually since then, including on March 11, 2019, the Board of Directors extended the repurchase program and this year authorized an increase to purchase up to $50 million of common stock during the 12 month period commencing again on 2019, a total of 10,320,487 shares had been repurchased under all programs at a cost of $329,122,000. We are not obligated to purchase shares under our stock repurchase program outside of its Rule 10b5-1 trading plan.

Commitments, Contingent Liabili

Commitments, Contingent Liabilities and Other Tax Matters	9 Months Ended
	Sep. 30, 2019
Commitments, Contingent Liabilities and Other Tax Matters
Commitments, Contingent Liabilities and Other Tax Matters	Note 10 — Commitments and Contingent Liabilities and Other Tax Matters ​ We are involved in various legal proceedings that are in various stages of litigation. We have determined, based on discussions with its counsel, that any material loss in such actions, individually or in the aggregate, is remote or the damages sought, even if fully recovered, would not be considered material to our consolidated financial position or results of operations. However, many of these matters are in various stages of proceedings and further developments could cause management to revise its assessment of these matters.

Capital Ratios

Capital Ratios	9 Months Ended
	Sep. 30, 2019
Capital Requirements
Capital Requirements	Note 11 — Capital Ratios ​ Banks and bank holding companies are subject to various regulatory capital requirements administered by state and federal banking agencies. Capital adequacy guidelines and, additionally for banks, prompt corrective action regulations, involve quantitative measures of assets, liabilities, and certain off-balance sheet items calculated under regulatory accounting practices. Capital amount and classifications are also subject to qualitative judgements by regulators about components, risk-weighting and other factors. ​ On November 21, 2017, the OCC, the Federal Reserve and the FDIC finalized a proposed rule that extends the current treatment under the regulatory capital rules for certain regulatory capital deductions and risk weights and certain minority interest requirements, as they apply to banking organizations that are not subject to the advanced approaches capital rules. Effective January 1, 2018, the rule also pauses the full transition to the Basel III treatment of mortgage servicing assets, certain deferred tax assets, investments in the capital of unconsolidated financial institutions and minority interests. The agencies are also considering whether to make adjustments to the capital rules in response to CECL (the FASB Standard relating to current expected credit loss) and its potential impact on regulatory capital. On December 7, 2017, the Basel Committee on Banking Supervision unveiled the latest round of its regulatory capital framework, commonly called “Basel IV.” The framework makes changes to the capital framework first introduced as “Basel III” in 2010. The committee targeted 2022-2027 as the timeframe for implementation by regulators in individual countries, including the U.S. federal bank regulatory agencies (after notice and comment). ​ On May 24, 2018, the EGRRCPA was enacted and, among other things, it includes a simplified capital rule change which effectively exempts banks with assets of less than $10 billion that exceed the “community bank leverage ratio,” from all risk-based capital requirements, including Basel III and its predecessors. The federal banking agencies must establish the “community bank leverage ratio” (a ratio of tangible equity to average consolidated assets) between 8% and 10% before community banks can begin to take advantage of this regulatory relief provision. Some of the Subsidiary Banks, with assets of less than $10 billion, may qualify for this exemption. Additionally, under the EGRRCPA, qualified bank holding companies with assets of up to $3 billion (currently $1 billion) will be eligible for the Federal Reserve’s Small Bank Holding Company Policy Statement, which eases limitations on the issuance of debt by holding companies. On August 28, 2018, the Federal Reserve issued an interim final rule expanding the applicability of its Small Bank Holding Company Policy Statement. While holding companies that meet the conditions of the policy statement are excluded from consolidated capital requirements, their depository institutions continue to be subject to minimum capital requirements. Finally, for banks that continue to be subject to the risk-based capital rules of Basel III (e.g., 150%), certain commercial real estate loans that were formally classified as high volatility commercial real estate 31 (“HVCRE”) will not be subject to heightened risk weights if they meet certain criteria. Also, while acquisition, development, and construction (“ADC”) loans will generally be subject to heightened risk weights, certain exceptions will apply. On September 18, 2018, the federal banking agencies issued a proposed rule modifying the agencies’ capital rules for HVCRE. ​ We had a CET1 to risk-weighted assets ratio of 17.98% on September 30, 2019 and 17.55 % on December 31, 2018. We had a Tier 1 capital-to-average-total-asset (leverage) ratio of 16.06% and 15.87%, risk-weighted Tier 1 capital ratio of 19.20% and 19.06% and risk-weighted total capital ratio of 19.85% and 19.74 % at September 30, 2019 and December 31, 2018, respectively. Our CET1 capital consists of common stock and related surplus, net of treasury stock, and retained earnings. We and our Subsidiary Banks elected to opt-out of the requirement to include most components of accumulated other comprehensive income (loss) in the calculation of CET1 capital. CET1 is reduced by goodwill and other intangible assets, net of associated deferred tax liabilities and subject to transition provisions. Tier 1 capital includes CET1 capital and additional Tier 1 capital. Additional Tier 1 capital includes the Capital and Common Securities issued by the Trusts (see Note 8 above) up to a maximum of 25 % of Tier 1 capital on an aggregate basis. Any amount that exceeds the 25 % threshold qualifies as Tier 2 capital. As of September 30, 2019, the total of $134,642,000 of the Capital and Common Securities outstanding qualified as Tier 1 capital. We actively monitor the regulatory capital ratios to ensure that our Subsidiary Banks are well-capitalized under the regulatory framework. ​ The CET1, Tier 1 and Total capital ratios are calculated by dividing the respective capital amounts by risk-weighted assets. Risk-weighted assets are calculated based on regulatory requirements and include total assets, excluding goodwill and other intangible assets, allocated by risk-weight category, and certain off-balance-sheet items, among other things. The leverage ratio is calculated by dividing Tier 1 capital by adjusted quarterly average total assets, which exclude goodwill and other intangible assets, among other things. ​ We and our Subsidiary Banks are subject to the regulatory capital requirements administered by the Federal Reserve, and, for our Subsidiary Banks, the FDIC. Regulatory authorities can initiate certain mandatory actions if we or any of our Subsidiary Banks fail to meet the minimum capital requirements, which could have a direct material effect on our financial statements. Management believes, as of September 30, 2019, that we and each of our Subsidiary Banks meet all capital adequacy requirements to which we are subject.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value
Assets and liabilities measured at fair value on a recurring basis	The following table represents assets and liabilities reported on the consolidated balance sheets at their fair value on a recurring basis as of September 30, 2019 by level within the fair value measurement hierarchy: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at ​ ​ ​ ​ ​ ​ Reporting Date Using ​ ​ ​ ​ ​ ​ (in Thousands) ​ ​ ​ ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Active ​ Significant ​ ​ ​ ​ ​ ​ Assets/Liabilities ​ Markets for ​ Other ​ Significant ​ ​ ​ Measured at ​ Identical ​ Observable ​ Unobservable ​ ​ ​ Fair Value ​ Assets ​ Inputs ​ Inputs ​ ​ ​ September 30, 2019 ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Measured on a recurring basis: ​ ​ ​ ​ ​ Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available for sale debt securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Residential mortgage-backed securities ​ $ 3,097,409 ​ $ — ​ $ 3,097,409 ​ $ — ​ States and political subdivisions ​ 95,462 ​ — ​ 95,462 ​ — ​ Equity Securities ​ 6,172 ​ 6,172 ​ — ​ — ​ ​ ​ $ 3,199,043 ​ $ 6,172 ​ $ 3,192,871 ​ $ — ​ ​ The following table represents assets and liabilities reported on the consolidated balance sheets at their fair value on a recurring basis as of December 31, 2018 by level within the fair value measurement hierarchy: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at ​ ​ ​ ​ ​ ​ Reporting Date Using ​ ​ ​ ​ ​ ​ (in Thousands) ​ ​ ​ ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Active ​ Significant ​ ​ ​ ​ ​ ​ Assets/Liabilities ​ Markets for ​ Other ​ Significant ​ ​ ​ Measured at ​ Identical ​ Observable ​ Unobservable ​ ​ ​ Fair Value ​ Assets ​ Inputs ​ Inputs ​ ​ ​ December 31, 2018 ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Measured on a recurring basis: ​ ​ ​ ​ ​ Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available for sale securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Residential mortgage - backed securities ​ $ 3,223,010 ​ $ — ​ $ 3,223,010 ​ $ — ​ States and political subdivisions ​ 188,340 ​ — ​ 188,340 ​ — ​ Equity Securities ​ 5,937 ​ 5,937 ​ — ​ — ​ ​ ​ $ 3,417,287 ​ $ 5,937 ​ $ 3,411,350 ​ $ — ​
Assets measured at fair value on a non-recurring basis	The following table represents financial instruments measured at fair value on a non-recurring basis as of and for the period ended September 30, 2019 by level within the fair value measurement hierarchy: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting ​ ​ ​ ​ ​ ​ ​ ​ Date Using ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assets/Liabilities ​ Prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Measured at ​ Active ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ Fair Value ​ Markets for ​ Other ​ Significant ​ Net Provision ​ ​ Period ended ​ Identical ​ Observable ​ Unobservable ​ (Credit) ​ ​ September 30, ​ Assets ​ Inputs ​ Inputs ​ During ​ ​ 2019 ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Period Measured on a non-recurring basis: ​ ​ ​ ​ ​ Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Impaired loans ​ $ 914 ​ $ — ​ $ — ​ $ 914 ​ $ 189 Other real estate owned ​ 27,376 ​ — ​ — ​ 27,376 ​ 154 Equity investments without readily determinable fair values ​ ​ 28,166 ​ ​ — ​ ​ — ​ ​ 28,166 ​ ​ 4,775 ​ The following table represents financial instruments measured at fair value on a non-recurring basis as of and for the period ended December 31, 2018 by level within the fair value measurement hierarchy: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting ​ ​ ​ ​ ​ ​ ​ ​ ​ Date Using ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assets/Liabilities ​ Prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Measured at ​ Active ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value ​ Markets ​ Other ​ Significant ​ Net (Credit) ​ ​ ​ Year ended ​ for Identical ​ Observable ​ Unobservable ​ Provision ​ ​ ​ December 31, ​ Assets ​ Inputs ​ Inputs ​ During ​ ​ ​ 2018 ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Period ​ Measured on a non-recurring basis: ​ ​ ​ ​ ​ ​ Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Impaired loans ​ $ 1,563 ​ $ — ​ $ — ​ $ 1,563 ​ $ 356 ​ Other real estate owned ​ 38,871 ​ — ​ — ​ 38,871 ​ 3,071 ​ ​

Loans (Tables)

Loans (Tables)	9 Months Ended
	Sep. 30, 2019
Loans
Summary of loans, by loan type	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2019 ​ 2018 ​ ​ ​ (Dollars in Thousands) ​ Commercial, financial and agricultural $ 3,504,936 $ 3,305,124 ​ Real estate - mortgage ​ 1,151,764 ​ 1,173,101 ​ Real estate - construction ​ 2,044,410 ​ 1,886,231 ​ Consumer ​ 47,072 ​ 46,316 ​ Foreign ​ 146,960 ​ 150,517 ​ Total loans ​ $ 6,895,142 ​ $ 6,561,289 ​

Allowance for Probable Loan L_2

Allowance for Probable Loan Losses (Tables)	9 Months Ended
	Sep. 30, 2019
Allowance for Probable Loan Losses
Loans individually or collectively evaluated for their impairment and related allowance, by loan class	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2019 ​ ​ ​ ​ ​ ​ Domestic ​ Foreign ​ ​ ​ ​ ​ ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Real Estate: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Construction & ​ Real Estate: ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Land ​ Farmland & ​ Real Estate: ​ Residential: ​ Residential: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ Development ​ Commercial ​ Multifamily ​ First Lien ​ Junior Lien ​ Consumer ​ Foreign ​ Total ​ ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at June 30, ​ $ 11,780 ​ $ 15,273 ​ $ 17,029 ​ $ 1,849 ​ $ 3,627 ​ $ 7,312 ​ $ 488 ​ $ 845 ​ $ 58,203 ​ Losses charged to allowance ​ (3,231) ​ — ​ (468) ​ — ​ (164) ​ (214) ​ (216) ​ — ​ (4,293) ​ Recoveries credited to allowance ​ 585 ​ 4 ​ 10 ​ — ​ 3 ​ 65 ​ 5 ​ — ​ 672 ​ Net (losses) recoveries charged to allowance ​ (2,646) ​ 4 ​ (458) ​ — ​ (161) ​ (149) ​ (211) ​ — ​ (3,621) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provision charged to operations ​ 1,837 ​ 1,573 ​ 230 ​ 350 ​ 263 ​ 852 ​ 199 ​ (26) ​ 5,278 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at September 30, ​ $ 10,971 ​ $ 16,850 ​ $ 16,801 ​ $ 2,199 ​ $ 3,729 ​ $ 8,015 ​ $ 476 ​ $ 819 ​ $ 59,860 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ Domestic ​ Foreign ​ ​ ​ ​ ​ ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Real Estate: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Construction & ​ Real Estate: ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Land ​ Farmland & ​ Real Estate: ​ Residential: ​ Residential: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ Development ​ Commercial ​ Multifamily ​ First Lien ​ Junior Lien ​ Consumer ​ Foreign ​ Total ​ ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at June 30, ​ $ 16,596 ​ $ 14,703 ​ $ 18,296 ​ $ 1,574 ​ $ 3,591 ​ $ 6,793 ​ $ 450 ​ $ 850 ​ $ 62,853 ​ Losses charged to allowance ​ (6,798) ​ — ​ — ​ ​ — ​ (74) ​ (133) ​ (80) ​ (3) ​ (7,088) ​ Recoveries credited to allowance ​ 489 ​ 4 ​ 19 ​ — ​ 23 ​ 53 ​ 12 ​ 9 ​ 609 ​ Net (losses) recoveries charged to allowance ​ (6,309) ​ 4 ​ 19 ​ — ​ (51) ​ (80) ​ (68) ​ 6 ​ (6,479) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provision charged to operations ​ 3,039 ​ 397 ​ 1,050 ​ (138) ​ (354) ​ 194 ​ 57 ​ 35 ​ 4,280 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at September 30, ​ $ 13,326 ​ $ 15,104 ​ $ 19,365 ​ $ 1,436 ​ $ 3,186 ​ $ 6,907 ​ $ 439 ​ $ 891 ​ $ 60,654 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2019 ​ ​ ​ ​ ​ Domestic ​ Foreign ​ ​ ​ ​ ​ ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Real Estate: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Construction & ​ Real Estate: ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Land ​ Farmland & ​ Real Estate: ​ Residential: ​ Residential: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ Development ​ Commercial ​ Multifamily ​ First Lien ​ Junior Lien ​ Consumer ​ Foreign ​ Total ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at December 31, ​ $ 12,596 ​ $ 15,123 ​ $ 19,353 ​ $ 1,808 ​ $ 3,467 ​ $ 7,719 ​ $ 447 ​ $ 871 ​ $ 61,384 Losses charged to allowance ​ (11,011) ​ — ​ (7,347) ​ — ​ ​ (166) ​ (314) ​ (334) ​ — ​ (19,172) Recoveries credited to allowance ​ 1,631 ​ 80 ​ 308 ​ — ​ 14 ​ 222 ​ 30 ​ — ​ 2,285 Net (losses) recoveries charged to allowance ​ (9,380) ​ 80 ​ (7,039) ​ — ​ (152) ​ (92) ​ (304) ​ — ​ (16,887) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provision charged to operations ​ 7,755 ​ 1,647 ​ 4,487 ​ 391 ​ 414 ​ 388 ​ 333 ​ (52) ​ 15,363 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at September 30, ​ $ 10,971 ​ $ 16,850 ​ $ 16,801 ​ $ 2,199 ​ $ 3,729 ​ $ 8,015 ​ $ 476 ​ $ 819 ​ $ 59,860 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ Domestic ​ Foreign ​ ​ ​ ​ ​ ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Real Estate: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Construction & ​ Real Estate: ​ Commercial ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Land ​ Farmland & ​ Real Estate: ​ Residential: ​ Residential: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ Development ​ Commercial ​ Multifamily ​ First Lien ​ Junior Lien ​ Consumer ​ Foreign ​ Total ​ ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at December 31, ​ $ 27,905 ​ $ 11,675 ​ $ 16,663 ​ $ 1,109 ​ $ 2,950 ​ $ 6,103 ​ $ 440 ​ $ 842 ​ $ 67,687 ​ Losses charged to allowance ​ (11,798) ​ ​ (1) ​ (70) ​ — ​ (118) ​ (172) ​ (262) ​ (3) ​ (12,424) ​ Recoveries credited to allowance ​ 1,520 ​ 8 ​ 229 ​ — ​ 25 ​ 348 ​ 39 ​ 10 ​ 2,179 ​ Net (losses) recoveries charged to allowance ​ (10,278) ​ 7 ​ 159 ​ — ​ (93) ​ 176 ​ (223) ​ 7 ​ (10,245) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provision charged to operations ​ (4,301) ​ 3,422 ​ 2,543 ​ 327 ​ 329 ​ 628 ​ 222 ​ 42 ​ 3,212 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at September 30, ​ $ 13,326 ​ $ 15,104 ​ $ 19,365 ​ $ 1,436 ​ $ 3,186 ​ $ 6,907 ​ $ 439 ​ $ 891 ​ $ 60,654 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ ​ Loans Individually ​ Loans Collectively ​ ​ ​ Evaluated For ​ Evaluated For ​ ​ ​ Impairment ​ Impairment ​ ​ ​ Recorded ​ ​ ​ ​ Recorded ​ ​ ​ ​ ​ ​ Investment ​ Allowance ​ Investment ​ Allowance ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 7,412 $ 395 $ 1,288,324 $ 10,576 ​ Commercial real estate: other construction & land development ​ 1,794 ​ 116 ​ 2,042,616 ​ 16,734 ​ Commercial real estate: farmland & commercial ​ 1,740 ​ — ​ 1,965,371 ​ 16,801 ​ Commercial real estate: multifamily ​ 649 ​ — ​ 241,440 ​ 2,199 ​ Residential: first lien ​ 6,286 ​ — ​ 432,186 ​ 3,729 ​ Residential: junior lien ​ 704 ​ — ​ 712,588 ​ 8,015 ​ Consumer ​ 1,131 ​ — ​ 45,941 ​ 476 ​ Foreign ​ 273 ​ — ​ 146,687 ​ 819 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total ​ $ 19,989 ​ $ 511 ​ $ 6,875,153 ​ $ 59,349 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ ​ Loans Individually ​ Loans Collectively ​ ​ ​ Evaluated For ​ Evaluated For ​ ​ ​ Impairment ​ Impairment ​ ​ ​ Recorded ​ ​ ​ ​ Recorded ​ ​ ​ ​ ​ ​ Investment ​ Allowance ​ Investment ​ Allowance ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 9,179 $ 656 $ 1,119,790 $ 11,940 ​ Commercial real estate: other construction & land development ​ 2,092 ​ 116 ​ 1,884,139 ​ 15,007 ​ Commercial real estate: farmland & commercial ​ 3,509 ​ — ​ 1,946,389 ​ 19,353 ​ Commercial real estate: multifamily ​ 507 ​ — ​ 225,750 ​ 1,808 ​ Residential: first lien ​ 6,244 ​ — ​ 439,556 ​ 3,467 ​ Residential: junior lien ​ 901 ​ — ​ 726,400 ​ 7,719 ​ Consumer ​ 1,175 ​ — ​ 45,141 ​ 447 ​ Foreign ​ 293 ​ — ​ 150,224 ​ 871 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total ​ $ 23,900 ​ $ 772 ​ $ 6,537,389 ​ $ 60,612 ​
Loans accounted on non-accrual basis, by loan class	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ December 31, 2018 ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ Commercial $ 7,379 $ 9,143 ​ Commercial real estate: other construction & land development ​ 1,794 ​ 2,092 ​ Commercial real estate: farmland & commercial ​ 1,740 ​ 3,509 ​ Commercial real estate: multifamily ​ 649 ​ 507 ​ Residential: first lien ​ 583 ​ 347 ​ Residential: junior lien ​ — ​ 171 ​ Consumer ​ 5 ​ 22 ​ Total non-accrual loans ​ $ 12,150 ​ $ 15,791 ​
Impaired loans, by loan class	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quarter to Date ​ Year to Date ​ ​ ​ ​ ​ Unpaid ​ ​ ​ ​ Average ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Recorded ​ Principal ​ Related ​ Recorded ​ Interest ​ Recorded ​ Interest ​ ​ Investment ​ Balance ​ Allowance ​ Investment ​ Recognized ​ Investment ​ Recognized ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ Loans with Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ $ 598 ​ $ 621 ​ $ 395 ​ $ 602 ​ $ — ​ $ 616 ​ $ — Commercial real estate: other construction & land development ​ ​ 128 ​ ​ 169 ​ ​ 116 ​ 129 ​ — ​ ​ 132 ​ ​ — Total impaired loans with related allowance ​ $ 726 ​ $ 790 ​ $ 511 ​ $ 731 ​ $ — ​ $ 748 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ Quarter to Date ​ Year to Date ​ ​ ​ ​ ​ Unpaid ​ Average ​ ​ Average ​ ​ ​ ​ Recorded ​ Principal ​ Recorded ​ Interest ​ Recorded ​ Interest ​ ​ Investment ​ Balance ​ Investment ​ Recognized ​ Investment ​ Recognized ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ Loans with No Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ $ 6,814 ​ $ 6,963 ​ $ 8,002 ​ $ 1 ​ $ 17,945 ​ $ 2 Commercial real estate: other construction & land development ​ 1,666 ​ 1,953 ​ 1,674 ​ — ​ 1,767 ​ — Commercial real estate: farmland & commercial ​ 1,740 ​ 2,368 ​ 3,222 ​ — ​ 22,389 ​ — Commercial real estate: multifamily ​ 649 ​ 684 ​ 653 ​ — ​ 656 ​ — Residential: first lien ​ 6,286 ​ 6,400 ​ 6,427 ​ 78 ​ 6,698 ​ 231 Residential: junior lien ​ 704 ​ 708 ​ 914 ​ 10 ​ 1,028 ​ 32 Consumer ​ 1,131 ​ 1,131 ​ 1,131 ​ — ​ ​ 1,088 ​ — Foreign ​ 273 ​ 273 ​ 274 ​ 3 ​ 281 ​ 9 Total impaired loans with no related allowance ​ $ 19,263 ​ $ 20,480 ​ $ 22,297 ​ $ 92 ​ $ 51,852 ​ $ 274 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ ​ ​ ​ Unpaid ​ ​ ​ ​ Average ​ ​ ​ ​ ​ ​ Recorded ​ Principal ​ Related ​ Recorded ​ Interest ​ ​ ​ Investment ​ Balance ​ Allowance ​ Investment ​ Recognized ​ ​ ​ (Dollars in Thousands) Loans with Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ $ 1,563 ​ $ 2,161 ​ $ 656 ​ $ 1,741 ​ $ — ​ Commercial real estate: other construction & land development ​ ​ 135 ​ ​ 169 ​ ​ 116 ​ 141 ​ — ​ Total impaired loans with related allowance ​ $ 1,698 ​ $ 2,330 ​ $ 772 ​ $ 1,882 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ ​ ​ ​ Unpaid Average ​ ​ ​ ​ ​ ​ Recorded ​ Principal Recorded ​ Interest ​ ​ ​ Investment ​ Balance Investment ​ Recognized ​ ​ ​ (Dollars in Thousands) Loans with No Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 7,616 ​ $ 7,730 ​ $ 16,194 ​ $ 3 ​ Commercial real estate: other construction & land development ​ 1,957 ​ 2,205 ​ 2,151 ​ — ​ Commercial real estate: farmland & commercial ​ 3,509 ​ 4,031 ​ 36,632 ​ — ​ Commercial real estate: multifamily ​ 507 ​ 538 ​ 565 ​ — ​ Residential: first lien ​ 6,244 ​ 6,386 ​ 7,136 ​ 305 ​ Residential: junior lien ​ 901 ​ 911 ​ 976 ​ 44 ​ Consumer ​ 1,175 ​ 1,190 ​ 1,211 ​ 2 ​ Foreign ​ 293 ​ 293 ​ 327 ​ 14 ​ Total impaired loans with no related allowance ​ $ 22,202 ​ $ 23,284 ​ $ 65,192 ​ $ 368 ​ ​ ​ ​ The following table details key information regarding our impaired loans by loan class at September 30, 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2018 ​ ​ Quarter to Date ​ ​ Year to Date ​ ​ Average ​ ​ ​ Average ​ ​ ​ ​ ​ Recorded ​ Interest ​ Recorded ​ Interest ​ ​ Investment ​ Recognized ​ Investment ​ Recognized ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ Loans with Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ $ 1,620 ​ $ — ​ $ 1,794 ​ $ — Commercial real estate: other construction & land development ​ 139 ​ — ​ 142 ​ — Total impaired loans with related allowance ​ $ 1,759 ​ $ — ​ $ 1,936 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2018 ​ ​ Quarter to Date ​ Year to Date ​ ​ Average ​ ​ Average ​ ​ ​ ​ ​ Recorded ​ Interest Recorded ​ Interest ​ ​ Investment ​ Recognized Investment ​ Recognized ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ Loans with No Related Allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 15,758 ​ $ — ​ $ 16,464 ​ $ 2 Commercial real estate: other construction & land development ​ 1,994 ​ — ​ 2,203 ​ — Commercial real estate: farmland & commercial ​ 5,986 ​ — ​ 36,633 ​ — Commercial real estate: multifamily ​ 590 ​ — ​ 575 ​ — Residential: first lien ​ 6,362 ​ 76 ​ 6,929 ​ 228 Residential: junior lien ​ 743 ​ 11 ​ 807 ​ 33 Consumer ​ 1,187 ​ 1 ​ 1,192 ​ 2 Foreign ​ 318 ​ 4 ​ 331 ​ 11 Total impaired loans with no related allowance ​ $ 32,938 ​ $ 92 ​ $ 65,134 ​ $ 276 ​
Loans accounted for as trouble debt restructuring, by loan class	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 December 31, 2018 ​ ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ Commercial $ 33 $ 35 ​ Residential: first lien ​ ​ 5,703 ​ ​ 5,947 ​ Residential: junior lien ​ ​ 704 ​ ​ 730 ​ Consumer ​ ​ 1,126 ​ ​ 1,153 ​ Foreign ​ ​ 273 ​ ​ 293 ​ ​ ​ ​ ​ ​ ​ ​ ​ Total troubled debt restructuring ​ $ 7,839 ​ $ 8,158 ​
Information regarding the aging of past due loans, by loan class	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 90 Days or ​ Total ​ ​ ​ ​ ​ ​ ​ ​ ​ 30 - 59 ​ 60 - 89 ​ 90 Days or ​ greater & ​ Past ​ ​ ​ ​ Total ​ ​ ​ Days ​ Days ​ Greater ​ still accruing ​ Due ​ Current ​ Portfolio ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 3,493 $ 902 $ 7,408 $ 1,477 $ 11,803 $ 1,283,933 $ 1,295,736 ​ Commercial real estate: other construction & land development ​ 8,977 ​ 18,504 ​ 1,100 ​ 286 ​ 28,581 ​ 2,015,829 ​ 2,044,410 ​ Commercial real estate: farmland & commercial ​ 3,210 ​ 56,125 ​ 1,270 ​ 737 ​ 60,605 ​ 1,906,506 ​ 1,967,111 ​ Commercial real estate: multifamily ​ 24 ​ 290 ​ 1,265 ​ 764 ​ 1,579 ​ 240,510 ​ 242,089 ​ Residential: first lien ​ 2,961 ​ 1,169 ​ 3,303 ​ 2,930 ​ 7,433 ​ 431,039 ​ 438,472 ​ Residential: junior lien ​ 1,316 ​ 305 ​ 1,216 ​ 1,216 ​ 2,837 ​ 710,455 ​ 713,292 ​ Consumer ​ 770 ​ 128 ​ 69 ​ 69 ​ 967 ​ 46,105 ​ 47,072 ​ Foreign ​ 2,119 ​ 490 ​ 147 ​ 147 ​ 2,756 ​ 144,204 ​ 146,960 ​ Total past due loans ​ $ 22,870 ​ $ 77,913 ​ $ 15,778 ​ $ 7,626 ​ $ 116,561 ​ $ 6,778,581 ​ $ 6,895,142 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 90 Days or ​ Total ​ ​ ​ ​ ​ ​ ​ ​ ​ 30 - 59 ​ 60 - 89 ​ 90 Days or ​ greater & ​ Past ​ ​ ​ ​ Total ​ ​ ​ Days ​ Days ​ Greater ​ still accruing ​ Due ​ Current ​ Portfolio ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ Commercial ​ $ 4,651 $ 1,089 $ 19,851 $ 10,890 $ 25,591 $ 1,103,378 $ 1,128,969 ​ Commercial real estate: other construction & land development ​ 727 ​ 1,707 ​ 922 ​ 16 ​ 3,356 ​ 1,882,875 ​ 1,886,231 ​ Commercial real estate: farmland & commercial ​ 2,928 ​ 784 ​ 27,239 ​ 24,910 ​ 30,951 ​ 1,918,947 ​ 1,949,898 ​ Commercial real estate: multifamily ​ 927 ​ — ​ 578 ​ 71 ​ 1,505 ​ 224,752 ​ 226,257 ​ Residential: first lien ​ 3,998 ​ 1,677 ​ 3,362 ​ 3,079 ​ 9,037 ​ 436,763 ​ 445,800 ​ Residential: junior lien ​ 1,155 ​ 618 ​ 1,108 ​ 937 ​ 2,881 ​ 724,420 ​ 727,301 ​ Consumer ​ 486 ​ 19 ​ 45 ​ 32 ​ 550 ​ 45,766 ​ 46,316 ​ Foreign ​ 1,106 ​ 117 ​ 739 ​ 739 ​ 1,962 ​ 148,555 ​ 150,517 ​ Total past due loans ​ $ 15,978 ​ $ 6,011 ​ $ 53,844 ​ $ 40,674 ​ $ 75,833 ​ $ 6,485,456 ​ $ 6,561,289 ​
Summary of the loan portfolio by credit quality indicator, by loan class	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ ​ ​ ​ ​ Special ​ Watch ​ Watch List— ​ Watch List— ​ ​ ​ Pass ​ Review ​ List—Pass ​ Substandard ​ Impaired ​ ​ ​ ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 1,228,895 $ 19 $ 957 $ 58,453 $ 7,412 ​ Commercial real estate: other construction & land development ​ 1,948,752 ​ — ​ 37,566 ​ 56,298 ​ 1,794 ​ Commercial real estate: farmland & commercial ​ 1,771,180 ​ 7,975 ​ 34,067 ​ 152,149 ​ 1,740 ​ Commercial real estate: multifamily ​ 240,535 ​ — ​ — ​ 905 ​ 649 ​ Residential: first lien ​ 430,825 ​ — ​ 143 ​ 1,218 ​ 6,286 ​ Residential: junior lien ​ 711,747 ​ — ​ 841 ​ — ​ 704 ​ Consumer ​ 45,941 ​ — ​ — ​ — ​ 1,131 ​ Foreign ​ 146,550 ​ — ​ — ​ 137 ​ 273 ​ Total ​ $ 6,524,425 ​ $ 7,994 ​ $ 73,574 ​ $ 269,160 ​ $ 19,989 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ ​ ​ ​ ​ Special ​ Watch ​ Watch List— ​ Watch List— ​ ​ ​ Pass ​ Review ​ List—Pass ​ Substandard ​ Impaired ​ ​ ​ ​ ​ ​ (Dollars in Thousands) ​ Domestic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial $ 998,625 $ 441 $ 44,544 $ 76,180 $ 9,179 ​ Commercial real estate: other construction & land development ​ 1,817,098 ​ 1,648 ​ 9,055 ​ 56,338 ​ 2,092 ​ Commercial real estate: farmland & commercial ​ 1,726,711 ​ 62,046 ​ 38,373 ​ 119,259 ​ 3,509 ​ Commercial real estate: multifamily ​ 224,823 ​ — ​ — ​ 927 ​ 507 ​ Residential: first lien ​ 438,773 ​ — ​ 142 ​ 641 ​ 6,244 ​ Residential: junior lien ​ 725,538 ​ — ​ 862 ​ — ​ 901 ​ Consumer ​ 45,141 ​ — ​ — ​ — ​ 1,175 ​ Foreign ​ 150,224 ​ — ​ — ​ — ​ 293 ​ Total ​ $ 6,126,933 ​ $ 64,135 ​ $ 92,976 ​ $ 253,345 ​ $ 23,900 ​ ​

Stock Options (Tables)

Stock Options (Tables)	9 Months Ended
	Sep. 30, 2019
Stock Options
Summary of option activity under stock option plans	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Weighted ​ average ​ ​ ​ ​ ​ ​ ​ ​ average ​ remaining ​ Aggregate ​ ​ ​ Number of ​ exercise ​ contractual ​ intrinsic ​ ​ ​ options ​ price ​ term (years) ​ value ($) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in Thousands) ​ Options outstanding at December 31, 2018 788,977 ​ $ 25.91 ​ ​ ​ ​ ​ ​ Plus: Options granted 16,500 ​ 35.34 ​ ​ ​ ​ ​ ​ Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options exercised 87,663 ​ 17.30 ​ ​ ​ ​ ​ ​ Options expired — ​ — ​ ​ ​ ​ ​ ​ Options forfeited 34,576 ​ 26.95 ​ ​ ​ ​ ​ ​ Options outstanding at September 30, 2019 683,238 ​ 27.19 5.86 ​ $ 7,809 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options fully vested and exercisable at September 30, 2019 322,772 ​ $ 22.08 4.62 ​ $ 5,339 ​ ​

Investment Securities and Equ_2

Investment Securities and Equity Securities with Readily Determinable Fair Values (Tables)	9 Months Ended
	Sep. 30, 2019
Investment Securities and Equity Securities with Readily Determinable Fair Values
Amortized cost and estimated fair value by type of investment security	The amortized cost and estimated fair value by type of investment security at September 30, 2019 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Held to Maturity ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ unrealized ​ unrealized ​ Estimated ​ Carrying ​ ​ ​ cost ​ gains ​ losses ​ fair value ​ value ​ ​ ​ (Dollars in Thousands) ​ Other securities $ 2,400 $ — $ — $ 2,400 $ 2,400 ​ Total investment securities ​ $ 2,400 ​ $ — ​ $ — ​ $ 2,400 ​ $ 2,400 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available for Sale Debt Securities ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ unrealized ​ unrealized ​ Estimated ​ Carrying ​ ​ ​ cost ​ gains ​ losses ​ fair value ​ value (1) ​ ​ ​ (Dollars in Thousands) ​ Residential mortgage-backed securities $ 3,095,049 $ 19,558 $ (17,197) $ 3,097,410 $ 3,097,410 ​ Obligations of states and political subdivisions ​ 92,199 ​ 3,263 ​ — ​ 95,462 ​ 95,462 ​ Total investment securities ​ $ 3,187,248 ​ $ 22,821 ​ $ (17,197) ​ $ 3,192,872 ​ $ 3,192,872 ​ (1) Included in the carrying value of residential mortgage-backed securities are $514,847 of mortgage-backed securities issued by Ginnie Mae and $2,582,563 of mortgage-backed securities issued by Fannie Mae and Freddie Mac. ​ The amortized cost and estimated fair value by type of investment security at December 31, 2018 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Held to Maturity ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ unrealized ​ unrealized ​ Estimated ​ Carrying ​ ​ ​ cost ​ gains ​ losses ​ fair value ​ value ​ ​ ​ (Dollars in Thousands) ​ Other securities $ 1,200 $ — $ — $ 1,200 $ 1,200 ​ Total investment securities ​ $ 1,200 ​ $ — ​ $ — ​ $ 1,200 ​ $ 1,200 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available for Sale ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ Estimated ​ ​ ​ ​ ​ ​ Amortized ​ unrealized ​ unrealized ​ fair ​ Carrying ​ ​ ​ cost ​ gains ​ losses ​ value ​ value (1) ​ ​ ​ (Dollars in Thousands) ​ Residential mortgage-backed securities $ 3,295,366 $ 6,813 $ (79,169) $ 3,223,010 $ 3,223,010 ​ Obligations of states and political subdivisions ​ 185,799 ​ 2,646 ​ (105) ​ 188,340 ​ 188,340 ​ Total investment securities ​ $ 3,481,165 ​ $ 9,459 ​ $ (79,274) ​ $ 3,411,350 ​ $ 3,411,350 ​ (1) Included in the carrying value of residential mortgage-backed securities are $501,293 of mortgage-backed securities issued by Ginnie Mae and $2,721,717 of mortgage-backed securities issued by Fannie Mae and Freddie.
Amortized cost and fair value of investment securities, by contractual maturity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Held to Maturity ​ Available for Sale ​ ​ ​ Amortized ​ Estimated ​ Amortized ​ Estimated ​ ​ ​ Cost ​ fair value ​ Cost ​ fair value ​ ​ ​ (Dollars in Thousands) ​ Due in one year or less $ 1,075 $ 1,075 $ — $ — ​ Due after one year through five years ​ 1,325 ​ 1,325 ​ — ​ — ​ Due after five years through ten years ​ — ​ — ​ 2,243 ​ 2,267 ​ Due after ten years ​ — ​ — ​ 89,956 ​ 93,195 ​ Residential mortgage-backed securities ​ — ​ — ​ 3,095,049 ​ 3,097,410 ​ Total investment securities ​ $ 2,400 ​ $ 2,400 ​ $ 3,187,248 ​ $ 3,192,872 ​
Gross unrealized losses on investment securities and the related fair value	​ Gross unrealized losses on debt investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual debt securities have been in a continuous unrealized loss position at September 30, 2019, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less than 12 months ​ 12 months or more ​ Total ​ ​ ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized ​ ​ ​ Fair Value ​ Losses ​ Fair Value ​ Losses ​ Fair Value ​ Losses ​ ​ ​ (Dollars in Thousands) ​ Available for sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Residential mortgage-backed securities $ 209,786 $ (600) $ 1,593,578 $ (16,597) $ 1,803,364 $ (17,197) ​ ​ ​ $ 209,786 ​ $ (600) ​ $ 1,593,578 ​ $ (16,597) ​ $ 1,803,364 ​ $ (17,197) ​ ​ Gross unrealized losses on investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2018 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less than 12 months ​ 12 months or more ​ Total ​ ​ ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized ​ ​ ​ Fair Value ​ Losses ​ Fair Value ​ Losses ​ Fair Value ​ Losses ​ ​ ​ (Dollars in Thousands) ​ Available for sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Residential mortgage-backed securities $ 208,384 $ (2,124) $ 2,537,181 $ (77,045) $ 2,745,565 $ (79,169) ​ Obligations of states and political subdivisions ​ 12,756 ​ (99) ​ 512 ​ (6) ​ 13,268 ​ (105) ​ ​ ​ $ 221,140 ​ $ (2,223) ​ $ 2,537,693 ​ $ (77,051) ​ $ 2,758,833 ​ $ (79,274) ​ ​
Summary of unrealized and realized gains and losses recognized in net income on equity securities	​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ September 30, 2019 ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ Net gains recognized during the period on equity securities $ ​ 45 Less: Net gains and (losses) recognized during the period on equity securities sold during the period ​ ​ — ​ ​ ​ ​ ​ Unrealized gains recognized during the reporting period on equity securities still held at the reporting date ​ $ ​ 45 ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ September 30, 2018 ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ Net losses recognized during the period on equity securities $ ​ (62) Less: Net gains and (losses) recognized during the period on equity securities sold during the period ​ ​ (771) ​ ​ ​ ​ ​ Unrealized gains recognized during the reporting period on equity securities still held at the reporting date ​ $ ​ 709 ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended ​ ​ September 30, 2019 ​ ​ (Dollars in Thousands) ​ ​ ​ Net gains recognized during the period on equity securities $ ​ 235 Less: Net gains and (losses) recognized during the period on equity securities sold during the period ​ ​ — ​ ​ ​ ​ ​ Unrealized gains recognized during the reporting period on equity securities still held at the reporting date ​ $ ​ 235 ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended ​ ​ September 30, 2018 ​ ​ (Dollars in Thousands) ​ ​ ​ Net losses recognized during the period on equity securities $ ​ (1,083) Less: Net gains and (losses) recognized during the period on equity securities sold during the period ​ ​ (771) ​ ​ ​ ​ ​ Unrealized losses recognized during the reporting period on equity securities still held at the reporting date ​ $ ​ (312)

Junior Subordinated Interest _2

Junior Subordinated Interest Deferrable Debentures (Tables)	9 Months Ended
	Sep. 30, 2019
Junior Subordinated Interest Deferrable Debentures
Junior subordinated deferrable interest debentures, major types of business trusts	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Junior ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subordinated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferrable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest ​ Repricing ​ Interest ​ Interest ​ ​ ​ Optional ​ ​ ​ Debentures ​ Frequency ​ Rate ​ Rate Index(1) ​ Maturity Date ​ Redemption Date (1) ​ ​ ​ (Dollars in Thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trust VIII ​ $ 25,774 Quarterly 5.35 % LIBOR + 3.05 October 2033 October 2008 ​ Trust IX ​ 41,238 Quarterly 3.94 % LIBOR + 1.62 October 2036 October 2011 ​ Trust X ​ 21,021 Quarterly 3.90 % LIBOR + 1.65 February 2037 February 2012 ​ Trust XI ​ 25,990 Quarterly 3.94 % LIBOR + 1.62 July 2037 July 2012 ​ Trust XII ​ 20,619 Quarterly 3.58 % LIBOR + 1.45 September 2037 September 2012 ​ ​ ​ $ 134,642 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The Capital and Common Securities may be redeemed in whole or in part on any interest payment date after the Optional Redemption Date.

Basis of Presentation (Details)

Basis of Presentation (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)segmentsubsidiary	Jan. 01, 2019USD ($)subsidiary
Basis of presentation
Number of operating segments | segment		1
Number of active operating bank subsidiaries | subsidiary		5
Number of non-bank subsidiaries that were dissolved | subsidiary			1
Right-of-use asset amortization	$ 267	$ 726
ASU 2016-02
Basis of presentation
Right-of-use asset			$ 6,400
Statement of Financial Position Location			us-gaap:OtherAssets
Lease liability			$ 6,400
Statement of Financial Position Location			us-gaap:OtherLiabilities

Fair Value (Fair Value By Level

Fair Value (Fair Value By Level) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets:
Available for sale debt securities	$ 3,192,872	$ 3,411,350
Equity Securities	6,172	5,937
Marketable Securities	3,201,444	3,418,487
Assets/liabilities measured at fair value
Assets:
Available for sale debt securities	3,192,872
Assets/liabilities measured at fair value | Residential mortgage-backed securities
Assets:
Available for sale debt securities	3,097,410	3,223,010
Assets/liabilities measured at fair value | Obligations of states and political subdivisions
Assets:
Available for sale debt securities	95,462	188,340
Measured on a recurring basis: | Assets/liabilities measured at fair value
Assets:
Marketable Securities	3,199,043	3,417,287
Measured on a recurring basis: | Assets/liabilities measured at fair value | Residential mortgage-backed securities
Assets:
Available for sale debt securities	3,097,409	3,223,010
Measured on a recurring basis: | Assets/liabilities measured at fair value | Obligations of states and political subdivisions
Assets:
Available for sale debt securities	95,462	188,340
Measured on a recurring basis: | Assets/liabilities measured at fair value | Equity securities with readily determinable fair values
Assets:
Equity Securities	6,172	5,937
Measured on a recurring basis: | Assets/liabilities measured at fair value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Marketable Securities	6,172	5,937
Measured on a recurring basis: | Assets/liabilities measured at fair value | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities with readily determinable fair values
Assets:
Equity Securities	6,172	5,937
Measured on a recurring basis: | Assets/liabilities measured at fair value | Significant Other Observable Inputs (Level 2)
Assets:
Marketable Securities	3,192,871	3,411,350
Measured on a recurring basis: | Assets/liabilities measured at fair value | Significant Other Observable Inputs (Level 2) | Residential mortgage-backed securities
Assets:
Available for sale debt securities	3,097,409	3,223,010
Measured on a recurring basis: | Assets/liabilities measured at fair value | Significant Other Observable Inputs (Level 2) | Obligations of states and political subdivisions
Assets:
Available for sale debt securities	$ 95,462	$ 188,340

Fair Value (Fair Value Measurem

Fair Value (Fair Value Measurement and Assumptions) (Details) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Sep. 30, 2019USD ($)loan	Dec. 31, 2018USD ($)
Assets:
Impaired Loans	$ 10,666		$ 10,666	$ 14,306
Assumptions used in discounted cash flow model to determine fair value of investments classified within level 3
Charges to allowance for probable loan losses in connection with other real estate owned	33	$ 9,500	$ 9,533	170
Number of loan foreclosures | loan			1
Adjustment to fair value in connection with other real estate owned	66		$ 154	3,071
Impaired commercial collateral dependent loans	10,666		10,666	14,306
Impaired commercial collateral dependent receivables appraisals to determine fair value within immediately preceding twelve months	7,184		7,184	10,911
Impaired collateral dependent commercial loans with internal evaluation completed within last twelve months	1,490		1,490	0
Measured on a non-recurring basis
Assumptions used in discounted cash flow model to determine fair value of investments classified within level 3
Change in net provision, impaired loans	189		189	356
Change in net provision, other real estate owned	154		154	3,071
Change in net provision, equity investment without readily determinable fair value	4,775		4,775
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3)
Assets:
Impaired Loans	914		914	1,563
Equity investments without readily determinable fair values	28,166		28,166
Non-financial assets:
Other real estate owned	27,376		27,376	38,871
Assumptions used in discounted cash flow model to determine fair value of investments classified within level 3
Impaired commercial collateral dependent loans	914		914	1,563
Measured on a non-recurring basis | Assets/liabilities measured at fair value
Assets:
Impaired Loans	914		914	1,563
Equity investments without readily determinable fair values	28,166		28,166
Non-financial assets:
Other real estate owned	27,376		27,376	38,871
Assumptions used in discounted cash flow model to determine fair value of investments classified within level 3
Impaired commercial collateral dependent loans	$ 914		$ 914	$ 1,563

Fair Value Measurements (Other

Fair Value Measurements (Other Assumptions) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Deposits
Carrying amount of time deposits	$ 1,981,369	$ 1,973,468
Significant Unobservable Inputs (Level 3)
Loans
Carrying amount of fixed rate performing loans	1,522,399	1,515,437
Estimated fair value of fixed rate performing loans	1,503,049	1,469,231
Deposits
Carrying amount of time deposits	1,981,369	1,973,468
Estimated fair value of time deposits	1,981,073	1,976,156
Significant Other Observable Inputs (Level 2)
Other borrowed funds
Carrying amount of the long-term FHLB borrowings	436,556	436,690
Estimated fair value of long-term FHLB borrowings	$ 463,409	$ 436,238

Loans (Details)

Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Summary of loans, by loan type
Total loans	$ 6,895,142	$ 6,561,289
Commercial, financial and agricultural
Summary of loans, by loan type
Total loans	3,504,936	3,305,124
Real estate - mortgage
Summary of loans, by loan type
Total loans	1,151,764	1,173,101
Commercial Real Estate:Other Construction and Land Development
Summary of loans, by loan type
Total loans	2,044,410	1,886,231
Consumer
Summary of loans, by loan type
Total loans	47,072	46,316
Foreign
Summary of loans, by loan type
Total loans	$ 146,960	$ 150,517

Allowance for Probable Loan L_3

Allowance for Probable Loan Losses (By Loan Class) (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Allowance for probable loan losses
Balance at the beginning of the period	$ 58,203		$ 61,384	$ 62,853	$ 61,384	$ 67,687
Losses charged to allowance	(4,293)			(7,088)	(19,172)	(12,424)
Recoveries credited to allowance	672			609	2,285	2,179
Net losses (recoveries) charged to allowance	(3,621)			(6,479)	(16,887)	(10,245)
Provision charged to operations	5,278			4,280	15,363	3,212
Balance at the end of the period	59,860	$ 58,203		60,654	59,860	60,654
Watch - List Impaired
Allowance for probable loan losses
Losses charged to allowance		9,500	9,500
Commercial
Allowance for probable loan losses
Balance at the beginning of the period	11,780		12,596	16,596	12,596	27,905
Losses charged to allowance	(3,231)			(6,798)	(11,011)	(11,798)
Recoveries credited to allowance	585			489	1,631	1,520
Net losses (recoveries) charged to allowance	(2,646)			(6,309)	(9,380)	(10,278)
Provision charged to operations	1,837			3,039	7,755	(4,301)
Balance at the end of the period	10,971	11,780		13,326	10,971	13,326
Commercial Real Estate:Other Construction and Land Development
Allowance for probable loan losses
Balance at the beginning of the period	15,273		15,123	14,703	15,123	11,675
Losses charged to allowance						(1)
Recoveries credited to allowance	4			4	80	8
Net losses (recoveries) charged to allowance	4			4	80	7
Provision charged to operations	1,573			397	1,647	3,422
Balance at the end of the period	16,850	15,273		15,104	16,850	15,104
Commercial Real Estate: Farmland and Commercial
Allowance for probable loan losses
Balance at the beginning of the period	17,029		19,353	18,296	19,353	16,663
Losses charged to allowance	(468)				(7,347)	(70)
Recoveries credited to allowance	10			19	308	229
Net losses (recoveries) charged to allowance	(458)			19	(7,039)	159
Provision charged to operations	230			1,050	4,487	2,543
Balance at the end of the period	16,801	17,029		19,365	16,801	19,365
Commercial Real Estate: Multifamily
Allowance for probable loan losses
Balance at the beginning of the period	1,849		1,808	1,574	1,808	1,109
Provision charged to operations	350			(138)	391	327
Balance at the end of the period	2,199	1,849		1,436	2,199	1,436
Residential First Lien
Allowance for probable loan losses
Balance at the beginning of the period	3,627		3,467	3,591	3,467	2,950
Losses charged to allowance	(164)			(74)	(166)	(118)
Recoveries credited to allowance	3			23	14	25
Net losses (recoveries) charged to allowance	(161)			(51)	(152)	(93)
Provision charged to operations	263			(354)	414	329
Balance at the end of the period	3,729	3,627		3,186	3,729	3,186
Residential Junior Lien
Allowance for probable loan losses
Balance at the beginning of the period	7,312		7,719	6,793	7,719	6,103
Losses charged to allowance	(214)			(133)	(314)	(172)
Recoveries credited to allowance	65			53	222	348
Net losses (recoveries) charged to allowance	(149)			(80)	(92)	176
Provision charged to operations	852			194	388	628
Balance at the end of the period	8,015	7,312		6,907	8,015	6,907
Consumer
Allowance for probable loan losses
Balance at the beginning of the period	488		447	450	447	440
Losses charged to allowance	(216)			(80)	(334)	(262)
Recoveries credited to allowance	5			12	30	39
Net losses (recoveries) charged to allowance	(211)			(68)	(304)	(223)
Provision charged to operations	199			57	333	222
Balance at the end of the period	476	488		439	476	439
Foreign
Allowance for probable loan losses
Balance at the beginning of the period	845		$ 871	850	871	842
Losses charged to allowance				(3)		(3)
Recoveries credited to allowance				9		10
Net losses (recoveries) charged to allowance				6		7
Provision charged to operations	(26)			35	(52)	42
Balance at the end of the period	$ 819	$ 845		$ 891	$ 819	$ 891

Allowance for Probable Loan L_4

Allowance for Probable Loan Losses (Impairment By Loan Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	$ 19,989	$ 23,900
Loans Individually Evaluated for Impairment, Allowance	511	772
Loans Collectively Evaluated for Impairment, Recorded Investment	6,875,153	6,537,389
Loans Collectively Evaluated for Impairment, Allowance	59,349	60,612
Commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	7,412	9,179
Loans Individually Evaluated for Impairment, Allowance	395	656
Loans Collectively Evaluated for Impairment, Recorded Investment	1,288,324	1,119,790
Loans Collectively Evaluated for Impairment, Allowance	10,576	11,940
Commercial Real Estate:Other Construction and Land Development
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	1,794	2,092
Loans Individually Evaluated for Impairment, Allowance	116	116
Loans Collectively Evaluated for Impairment, Recorded Investment	2,042,616	1,884,139
Loans Collectively Evaluated for Impairment, Allowance	16,734	15,007
Commercial Real Estate: Farmland and Commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	1,740	3,509
Loans Collectively Evaluated for Impairment, Recorded Investment	1,965,371	1,946,389
Loans Collectively Evaluated for Impairment, Allowance	16,801	19,353
Commercial Real Estate: Multifamily
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	649	507
Loans Collectively Evaluated for Impairment, Recorded Investment	241,440	225,750
Loans Collectively Evaluated for Impairment, Allowance	2,199	1,808
Residential First Lien
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	6,286	6,244
Loans Collectively Evaluated for Impairment, Recorded Investment	432,186	439,556
Loans Collectively Evaluated for Impairment, Allowance	3,729	3,467
Residential Junior Lien
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	704	901
Loans Collectively Evaluated for Impairment, Recorded Investment	712,588	726,400
Loans Collectively Evaluated for Impairment, Allowance	8,015	7,719
Consumer
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	1,131	1,175
Loans Collectively Evaluated for Impairment, Recorded Investment	45,941	45,141
Loans Collectively Evaluated for Impairment, Allowance	476	447
Foreign
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	273	293
Loans Collectively Evaluated for Impairment, Recorded Investment	146,687	150,224
Loans Collectively Evaluated for Impairment, Allowance	$ 819	$ 871

Allowance for Probable Loan L_5

Allowance for Probable Loan Losses (Non-accrual Basis By Loan Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Loan loss allowances, financing receivable past due
Non-accrual loans, total	$ 12,150	$ 15,791
Commercial
Loan loss allowances, financing receivable past due
Non-accrual loans, total	7,379	9,143
Commercial Real Estate:Other Construction and Land Development
Loan loss allowances, financing receivable past due
Non-accrual loans, total	1,794	2,092
Commercial Real Estate: Farmland and Commercial
Loan loss allowances, financing receivable past due
Non-accrual loans, total	1,740	3,509
Commercial Real Estate: Multifamily
Loan loss allowances, financing receivable past due
Non-accrual loans, total	649	507
Residential First Lien
Loan loss allowances, financing receivable past due
Non-accrual loans, total	583	347
Residential Junior Lien
Loan loss allowances, financing receivable past due
Non-accrual loans, total		171
Consumer
Loan loss allowances, financing receivable past due
Non-accrual loans, total	$ 5	$ 22

Allowance for Probable Loan L_6

Allowance for Probable Loan Losses (Impaired Loans) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2018
Interest Recognized
Total trouble debt restructuring	$ 7,839		$ 7,839	$ 8,158
Period of charge off for past due unsecured commercial loans	90 days		90 days
Class of Financing Receivable
Recorded investment:
Total impaired loans with related allowance	$ 726	$ 1,936	$ 726	1,698
Total impaired loans with no related allowance	19,263	65,134	19,263	22,202
Unpaid principal balance:
Total impaired loans with an allowance recorded	790		790	2,330
Total impaired loans with no related allowance recorded	20,480	276	20,480	23,284
Related Allowance	511		511	772
Average recorded investment:
Total impaired loans with an allowance recorded	731	1,759	748	1,882
Total impaired loans with no related allowance recorded	22,297	32,938	51,852	65,192
Interest Recognized
Total impaired loans with no related allowance recorded	92	92	274	368
Commercial
Interest Recognized
Total trouble debt restructuring	33		33	35
Commercial | Class of Financing Receivable
Recorded investment:
Total impaired loans with related allowance	598	1,794	598	1,563
Total impaired loans with no related allowance	6,814	16,464	6,814	7,616
Unpaid principal balance:
Total impaired loans with an allowance recorded	621		621	2,161
Total impaired loans with no related allowance recorded	6,963	2	6,963	7,730
Related Allowance	395		395	656
Average recorded investment:
Total impaired loans with an allowance recorded	602	1,620	616	1,741
Total impaired loans with no related allowance recorded	8,002	15,758	17,945	16,194
Interest Recognized
Total impaired loans with no related allowance recorded	1		2	3
Commercial Real Estate:Other Construction and Land Development | Class of Financing Receivable
Recorded investment:
Total impaired loans with related allowance	128	142	128	135
Total impaired loans with no related allowance	1,666	2,203	1,666	1,957
Unpaid principal balance:
Total impaired loans with an allowance recorded	169		169	169
Total impaired loans with no related allowance recorded	1,953		1,953	2,205
Related Allowance	116		116	116
Average recorded investment:
Total impaired loans with an allowance recorded	129	139	132	141
Total impaired loans with no related allowance recorded	1,674	1,994	1,767	2,151
Commercial Real Estate: Farmland and Commercial | Class of Financing Receivable
Recorded investment:
Total impaired loans with no related allowance	1,740	36,633	1,740	3,509
Unpaid principal balance:
Total impaired loans with no related allowance recorded	2,368		2,368	4,031
Average recorded investment:
Total impaired loans with no related allowance recorded	3,222	5,986	22,389	36,632
Commercial Real Estate: Multifamily | Class of Financing Receivable
Recorded investment:
Total impaired loans with no related allowance	649	575	649	507
Unpaid principal balance:
Total impaired loans with no related allowance recorded	684		684	538
Average recorded investment:
Total impaired loans with no related allowance recorded	653	590	656	565
Residential First Lien
Interest Recognized
Total trouble debt restructuring	5,703		5,703	5,947
Residential First Lien | Class of Financing Receivable
Recorded investment:
Total impaired loans with no related allowance	6,286	6,929	6,286	6,244
Unpaid principal balance:
Total impaired loans with no related allowance recorded	6,400	228	6,400	6,386
Average recorded investment:
Total impaired loans with no related allowance recorded	6,427	6,362	6,698	7,136
Interest Recognized
Total impaired loans with no related allowance recorded	78	76	231	305
Residential Junior Lien
Interest Recognized
Total trouble debt restructuring	704		704	730
Residential Junior Lien | Class of Financing Receivable
Recorded investment:
Total impaired loans with no related allowance	704	807	704	901
Unpaid principal balance:
Total impaired loans with no related allowance recorded	708	33	708	911
Average recorded investment:
Total impaired loans with no related allowance recorded	914	743	1,028	976
Interest Recognized
Total impaired loans with no related allowance recorded	10	11	32	44
Consumer
Interest Recognized
Total trouble debt restructuring	1,126		1,126	1,153
Consumer | Class of Financing Receivable
Recorded investment:
Total impaired loans with no related allowance	1,131	1,192	1,131	1,175
Unpaid principal balance:
Total impaired loans with no related allowance recorded	1,131	2	1,131	1,190
Average recorded investment:
Total impaired loans with no related allowance recorded	1,131	1,187	1,088	1,211
Interest Recognized
Total impaired loans with no related allowance recorded		1		2
Foreign
Interest Recognized
Total trouble debt restructuring	273		273	293
Foreign | Class of Financing Receivable
Recorded investment:
Total impaired loans with no related allowance	273	331	273	293
Unpaid principal balance:
Total impaired loans with no related allowance recorded	273	11	273	293
Average recorded investment:
Total impaired loans with no related allowance recorded	274	318	281	327
Interest Recognized
Total impaired loans with no related allowance recorded	$ 3	$ 4	$ 9	$ 14

Allowance for Probable Loan L_7

Allowance for Probable Loan Losses (Aging By Loan Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	$ 7,626	$ 40,674
Past due	116,561	75,833
Loans, current	6,778,581	6,485,456
Total loans	6,895,142	6,561,289
30 to 59 Days
Financing receivable recorded investment
Past due	22,870	15,978
60 to 89 Days
Financing receivable recorded investment
Past due	77,913	6,011
90 Days or Greater
Financing receivable recorded investment
Past due	15,778	53,844
Commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1,477	10,890
Past due	11,803	25,591
Loans, current	1,283,933	1,103,378
Total loans	1,295,736	1,128,969
Commercial | 30 to 59 Days
Financing receivable recorded investment
Past due	3,493	4,651
Commercial | 60 to 89 Days
Financing receivable recorded investment
Past due	902	1,089
Commercial | 90 Days or Greater
Financing receivable recorded investment
Past due	7,408	19,851
Commercial Real Estate:Other Construction and Land Development
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	286	16
Past due	28,581	3,356
Loans, current	2,015,829	1,882,875
Total loans	2,044,410	1,886,231
Commercial Real Estate:Other Construction and Land Development | 30 to 59 Days
Financing receivable recorded investment
Past due	8,977	727
Commercial Real Estate:Other Construction and Land Development | 60 to 89 Days
Financing receivable recorded investment
Past due	18,504	1,707
Commercial Real Estate:Other Construction and Land Development | 90 Days or Greater
Financing receivable recorded investment
Past due	1,100	922
Commercial Real Estate: Farmland and Commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	737	24,910
Past due	60,605	30,951
Loans, current	1,906,506	1,918,947
Total loans	1,967,111	1,949,898
Commercial Real Estate: Farmland and Commercial | 30 to 59 Days
Financing receivable recorded investment
Past due	3,210	2,928
Commercial Real Estate: Farmland and Commercial | 60 to 89 Days
Financing receivable recorded investment
Past due	56,125	784
Commercial Real Estate: Farmland and Commercial | 90 Days or Greater
Financing receivable recorded investment
Past due	1,270	27,239
Commercial Real Estate: Multifamily
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	764	71
Past due	1,579	1,505
Loans, current	240,510	224,752
Total loans	242,089	226,257
Commercial Real Estate: Multifamily | 30 to 59 Days
Financing receivable recorded investment
Past due	24	927
Commercial Real Estate: Multifamily | 60 to 89 Days
Financing receivable recorded investment
Past due	290
Commercial Real Estate: Multifamily | 90 Days or Greater
Financing receivable recorded investment
Past due	1,265	578
Residential First Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	2,930	3,079
Past due	7,433	9,037
Loans, current	431,039	436,763
Total loans	438,472	445,800
Residential First Lien | 30 to 59 Days
Financing receivable recorded investment
Past due	2,961	3,998
Residential First Lien | 60 to 89 Days
Financing receivable recorded investment
Past due	1,169	1,677
Residential First Lien | 90 Days or Greater
Financing receivable recorded investment
Past due	3,303	3,362
Residential Junior Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1,216	937
Past due	2,837	2,881
Loans, current	710,455	724,420
Total loans	713,292	727,301
Residential Junior Lien | 30 to 59 Days
Financing receivable recorded investment
Past due	1,316	1,155
Residential Junior Lien | 60 to 89 Days
Financing receivable recorded investment
Past due	305	618
Residential Junior Lien | 90 Days or Greater
Financing receivable recorded investment
Past due	1,216	1,108
Consumer
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	69	32
Past due	967	550
Loans, current	46,105	45,766
Total loans	47,072	46,316
Consumer | 30 to 59 Days
Financing receivable recorded investment
Past due	770	486
Consumer | 60 to 89 Days
Financing receivable recorded investment
Past due	128	19
Consumer | 90 Days or Greater
Financing receivable recorded investment
Past due	69	45
Foreign
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	147	739
Past due	2,756	1,962
Loans, current	144,204	148,555
Total loans	146,960	150,517
Foreign | 30 to 59 Days
Financing receivable recorded investment
Past due	2,119	1,106
Foreign | 60 to 89 Days
Financing receivable recorded investment
Past due	490	117
Foreign | 90 Days or Greater
Financing receivable recorded investment
Past due	$ 147	$ 739

Allowance for Probable Loan L_8

Allowance for Probable Loan Losses (Portfolio Credit Quality By Loan Class) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)item	Dec. 31, 2018USD ($)
Loan portfolio by credit quality indicator
Portfolio, total	$ 6,895,142	$ 6,561,289
Number of additional relationships reclassified from Pass to Watch List - Substandard | item	2
Pass
Loan portfolio by credit quality indicator
Portfolio, total	$ 6,524,425	6,126,933
Special Review
Loan portfolio by credit quality indicator
Portfolio, total	7,994	64,135
Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	73,574	92,976
Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	269,160	253,345
Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	19,989	23,900
Commercial
Loan portfolio by credit quality indicator
Portfolio, total	1,295,736	1,128,969
Commercial | Pass
Loan portfolio by credit quality indicator
Portfolio, total	1,228,895	998,625
Commercial | Special Review
Loan portfolio by credit quality indicator
Portfolio, total	19	441
Commercial | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	957	44,544
Commercial | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	58,453	76,180
Commercial | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	7,412	9,179
Commercial Real Estate:Other Construction and Land Development
Loan portfolio by credit quality indicator
Portfolio, total	2,044,410	1,886,231
Commercial Real Estate:Other Construction and Land Development | Pass
Loan portfolio by credit quality indicator
Portfolio, total	1,948,752	1,817,098
Commercial Real Estate:Other Construction and Land Development | Special Review
Loan portfolio by credit quality indicator
Portfolio, total		1,648
Commercial Real Estate:Other Construction and Land Development | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	37,566	9,055
Commercial Real Estate:Other Construction and Land Development | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	56,298	56,338
Commercial Real Estate:Other Construction and Land Development | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	1,794	2,092
Commercial Real Estate: Farmland and Commercial
Loan portfolio by credit quality indicator
Portfolio, total	1,967,111	1,949,898
Commercial Real Estate: Farmland and Commercial | Pass
Loan portfolio by credit quality indicator
Portfolio, total	1,771,180	1,726,711
Commercial Real Estate: Farmland and Commercial | Special Review
Loan portfolio by credit quality indicator
Portfolio, total	7,975	62,046
Commercial Real Estate: Farmland and Commercial | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	34,067	38,373
Commercial Real Estate: Farmland and Commercial | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	152,149	119,259
Commercial Real Estate: Farmland and Commercial | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	1,740	3,509
Commercial Real Estate: Multifamily
Loan portfolio by credit quality indicator
Portfolio, total	242,089	226,257
Commercial Real Estate: Multifamily | Pass
Loan portfolio by credit quality indicator
Portfolio, total	240,535	224,823
Commercial Real Estate: Multifamily | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	905	927
Commercial Real Estate: Multifamily | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	649	507
Residential First Lien
Loan portfolio by credit quality indicator
Portfolio, total	438,472	445,800
Residential First Lien | Pass
Loan portfolio by credit quality indicator
Portfolio, total	430,825	438,773
Residential First Lien | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	143	142
Residential First Lien | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	1,218	641
Residential First Lien | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	6,286	6,244
Residential Junior Lien
Loan portfolio by credit quality indicator
Portfolio, total	713,292	727,301
Residential Junior Lien | Pass
Loan portfolio by credit quality indicator
Portfolio, total	711,747	725,538
Residential Junior Lien | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	841	862
Residential Junior Lien | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	704	901
Consumer
Loan portfolio by credit quality indicator
Portfolio, total	47,072	46,316
Consumer | Pass
Loan portfolio by credit quality indicator
Portfolio, total	45,941	45,141
Consumer | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	1,131	1,175
Foreign
Loan portfolio by credit quality indicator
Portfolio, total	146,960	150,517
Foreign | Pass
Loan portfolio by credit quality indicator
Portfolio, total	146,550	150,224
Foreign | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	137
Foreign | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	$ 273	$ 293

Stock Options (Details)

Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Apr. 05, 2012
Stock options under 2012 Plan
Stock option details
Shares available for future grants	27,276		27,276		800,000
Maximum exercisable period for options granted			10 years
Stock option activity
Options outstanding at the beginning of the period (in shares)			788,977
Plus: Options granted (in shares)			16,500
Less:
Options exercised (in shares)			87,663
Options forfeited (in shares)			34,576
Options outstanding at the end of the period (in shares)	683,238		683,238
Options fully vested and exercisable at the end of the period (in shares)	322,772		322,772
Stock Options, Weighted average exercise price
Options outstanding at the beginning, weighted average exercise price (in dollars per share)			$ 25.91
Plus: Options granted, weighted average exercise price (in dollars per share)			35.34
Less:
Options exercised, weighted average exercise price (in dollars per share)			17.30
Options forfeited, weighted average exercise price (in dollars per share)			26.95
Options outstanding at the end, weighted average exercise price (in dollars per share)	$ 27.19		27.19
Options fully vested and exercisable at the end, weighted average exercise price (in dollars per share)	$ 22.08		$ 22.08
Stock Options, Weighted average remaining contractual term (years)
Options outstanding at the end, weighted average remaining contractual term (years)			5 years 10 months 9 days
Options fully vested and exercisable at the end, weighted average remaining contractual term (years)			4 years 7 months 13 days
Stock Options, Aggregate intrinsic value
Options outstanding at the end, aggregate intrinsic value	$ 7,809		$ 7,809
Options fully vested and exercisable at the end, aggregate intrinsic value	5,339		5,339
Stock-based compensation expense	240	$ 285	744	$ 755
Stock-based compensation cost, unrecognized, related to non-vested options	$ 2,158		$ 2,158
Stock-based compensation cost, unrecognized, related to non-vested options, weighted-average period of recognition			1 year 10 months 24 days
Incentive stock options granted to 10% shareholders
Stock option details
Maximum exercisable period for options granted			5 years

Investment Securities and Equ_3

Investment Securities and Equity Securities with Readily Determinable Fair Values (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Held-to-maturity securities
Amortized cost	$ 2,400	$ 1,200
Estimated fair value	2,400	1,200
Carrying Value	2,400	1,200
Available-for-sale securities
Amortized cost, Available-for-sale securities	3,187,248	3,481,165
Gross Unrealized Gains	22,821
Gross Unrealized Losses	(17,197)
Available for sale debt securities	3,192,872	3,411,350
Equity Securities	6,172	5,937
Total Amortized cost		3,481,165
Total Gross unrealized gains		9,459
Total Gross unrealized losses		79,274
Assets/liabilities measured at fair value
Available-for-sale securities
Available for sale debt securities	3,192,872
Available for sale debt securities and equity securities		3,411,350
Carrying Value
Available-for-sale securities
Available for sale debt securities	3,192,872
Available for sale debt securities and equity securities		3,411,350
Residential mortgage-backed securities
Available-for-sale securities
Amortized cost, Available-for-sale securities	3,095,049	3,295,366
Gross Unrealized Gains	19,558	6,813
Gross Unrealized Losses	(17,197)	(79,169)
Residential mortgage-backed securities | Assets/liabilities measured at fair value
Available-for-sale securities
Available for sale debt securities	3,097,410	3,223,010
Residential mortgage-backed securities | Carrying Value
Available-for-sale securities
Available for sale debt securities	3,097,410	3,223,010
Mortgage-backed securities by Ginnie Mae
Available-for-sale securities
Available for sale debt securities	514,847	501,293
Mortgage-backed securities by Fannie Mae and Freddie Mac
Available-for-sale securities
Available for sale debt securities	2,582,563	2,721,717
Obligations of states and political subdivisions
Available-for-sale securities
Amortized cost, Available-for-sale securities	92,199	185,799
Gross Unrealized Gains	3,263	2,646
Gross Unrealized Losses		(105)
Obligations of states and political subdivisions | Assets/liabilities measured at fair value
Available-for-sale securities
Available for sale debt securities	95,462	188,340
Obligations of states and political subdivisions | Carrying Value
Available-for-sale securities
Available for sale debt securities	95,462	188,340
Other securities
Held-to-maturity securities
Amortized cost	2,400	1,200
Estimated fair value	2,400	1,200
Carrying Value	$ 2,400	$ 1,200

Investment Securities and Equ_4

Investment Securities and Equity Securities with Readily Determinable Fair Values (Contractual Maturities and Estimated Fair Values) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Held-to-maturity debt securities amortized cost disclosures
Due in one year or less, held-to-maturity debt securities amortized cost	$ 1,075		$ 1,075
Due after one year through five years, held-to-maturity debt securities amortized cost	1,325		1,325
Amortized cost, held-to-maturity debt securities	2,400		2,400		$ 1,200
Held-to-maturity debt securities, Estimated fair value disclosures
Due in one year or less, held-to-maturity debt securities, Estimated fair value	1,075		1,075
Due after one year through five years, held-to-maturity debt securities, Estimated fair value	1,325		1,325
Estimated fair value	2,400		2,400		1,200
Available-for-sale debt securities amortized cost disclosures
Due after five years through ten years, available-for-sale debt securities amortized cost	2,243		2,243
Due after ten years, available-for-sale debt securities amortized cost	89,956		89,956
Residential mortgage-backed securities, amortized cost	3,095,049		3,095,049
Amortized cost, Available-for-sale securities	3,187,248		3,187,248		3,481,165
Available for sale debt securities, Estimated Fair Value Disclosures
Due after five years through ten years, available-for-sale debt securities, Estimated Fair Value	2,267		2,267
Due after ten years, available-for-sale debt securities, Estimated Fair Value	93,195		93,195
Residential mortgage-backed securities, Estimated Fair Value	3,097,410		3,097,410
Estimated fair value, Available for sale securities	3,192,872		3,192,872		$ 3,411,350
Proceeds from sales and calls of available for sale securities	32,285	$ 19,530	92,980	$ 37,675
Proceeds from sales of mortgage-backed securities	0	0	0	0
Gross gains realized on sales	1	2	4	3
Gross losses realized on sales	3	$ 0	16	$ 0
Collateral Pledged
Available-for-sale debt securities amortized cost disclosures
Amortized cost, Available-for-sale securities	1,143,623		1,143,623
Available for sale debt securities, Estimated Fair Value Disclosures
Fair value of available for sale investment securities pledged	$ 1,142,310		$ 1,142,310

Investment Securities and Equ_5

Investment Securities and Equity Securities with Readily Determinable Fair Values (Fair Value and Gross Unrealized Loss) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Available for sale:
Fair value, less than 12 months	$ 209,786	$ 221,140
Unrealized losses, less than 12 Months	(600)	(2,223)
Fair value, 12 months or more	1,593,578	2,537,693
Unrealized losses, 12 Months or More	(16,597)	(77,051)
Fair value, Total	1,803,364	2,758,833
Unrealized losses, Total	(17,197)	(79,274)
Residential mortgage-backed securities
Available for sale:
Fair value, less than 12 months	209,786	208,384
Unrealized losses, less than 12 Months	(600)	(2,124)
Fair value, 12 months or more	1,593,578	2,537,181
Unrealized losses, 12 Months or More	(16,597)	(77,045)
Fair value, Total	1,803,364	2,745,565
Unrealized losses, Total	$ (17,197)	(79,169)
Obligations of states and political subdivisions
Available for sale:
Fair value, less than 12 months		12,756
Unrealized losses, less than 12 Months		(99)
Fair value, 12 months or more		512
Unrealized losses, 12 Months or More		(6)
Fair value, Total		13,268
Unrealized losses, Total		$ (105)

Investment Securities and Equ_6

Investment Securities and Equity Securities with Readily Determinable Fair Values (Unrealized and realized gains and losses recognized in net income on equity securities ) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Investment Securities and Equity Securities with Readily Determinable Fair Values
Equity Securities	$ 6,172		$ 6,172		$ 5,937
Summary of unrealized and realized gains and losses recognized in net income on equity securities
Net gains (losses) recognized during the period on equity securities	45	$ (62)	235	$ (1,083)
Less: Net gains and (losses) recognized during the period on equity securities sold during the period		(771)		(771)
Unrealized gains (losses) recognized during the reporting period on equity securities still held at the reporting date	$ 45	$ 709	$ 235	$ (312)

Other Borrowed Funds (Details)

Other Borrowed Funds (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Federal Home Loan Bank advances
Other borrowed funds	$ 456,556	$ 705,665
Percentage of decrease in other borrowed funds	(35.30%)

Junior Subordinated Deferrable

Junior Subordinated Deferrable Interest Debentures (Details)	9 Months Ended
	Sep. 30, 2019USD ($)item	May 07, 2019USD ($)	Dec. 31, 2018USD ($)
Junior subordinated deferrable interest debentures, major types of business trusts
Number of statutory business trusts issuing trust preferred securities | item	5
Junior subordinated deferrable interest debentures	$ 134,642,000		$ 160,416,000
Maximum number of consecutive quarterly period available for deferral of interest payment on Trusts VI, VIII, IX, X, XI and XII | item	20
Percentage of capital securities issued by trust qualifying as Tier I capital, maximum	25.00%
Percentage of capital securities issued by trust qualifying as Tier II capital, minimum	25.00%
Capital securities issued by the trust, qualifying as Tier I capital	$ 134,642,000		$ 160,416,000
Trust VI
Junior subordinated deferrable interest debentures, major types of business trusts
Amount redeemed		$ 25,000,000
Trust XI
Junior subordinated deferrable interest debentures, major types of business trusts
Junior subordinated deferrable interest debentures	25,990,000
Trust X
Junior subordinated deferrable interest debentures, major types of business trusts
Junior subordinated deferrable interest debentures	$ 21,021,000

Junior Subordinated Deferrabl_2

Junior Subordinated Deferrable Interest Debentures (Key Information) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Junior subordinated deferrable interest debentures, major types of business trusts
Junior subordinated deferrable interest debentures	$ 134,642	$ 160,416
Trust VIII
Junior subordinated deferrable interest debentures, major types of business trusts
Junior subordinated deferrable interest debentures	$ 25,774
Interest rate (as a percent)	5.35%
Interest rate index	LIBOR
Spread on interest rate index (as a percent)	3.05%
Trust IX
Junior subordinated deferrable interest debentures, major types of business trusts
Junior subordinated deferrable interest debentures	$ 41,238
Interest rate (as a percent)	3.94%
Interest rate index	LIBOR
Spread on interest rate index (as a percent)	1.62%
Trust X
Junior subordinated deferrable interest debentures, major types of business trusts
Junior subordinated deferrable interest debentures	$ 21,021
Interest rate (as a percent)	3.90%
Interest rate index	LIBOR
Spread on interest rate index (as a percent)	1.65%
Trust XI
Junior subordinated deferrable interest debentures, major types of business trusts
Junior subordinated deferrable interest debentures	$ 25,990
Interest rate (as a percent)	3.94%
Interest rate index	LIBOR
Spread on interest rate index (as a percent)	1.62%
Trust XII
Junior subordinated deferrable interest debentures, major types of business trusts
Junior subordinated deferrable interest debentures	$ 20,619
Interest rate (as a percent)	3.58%
Interest rate index	LIBOR
Spread on interest rate index (as a percent)	1.45%

Common Stock and Dividends (Det

Common Stock and Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 15, 2019	Apr. 15, 2019	Oct. 16, 2018	Apr. 16, 2018	Apr. 09, 2017	Apr. 30, 2009	Sep. 30, 2018	Nov. 01, 2019	Apr. 09, 2019
Common Stock and Dividends
Payments for Repurchase of Warrants							$ 29,005
Cash dividends paid to common shareholders (in dollars per share)	$ 0.55	$ 0.50	$ 0.42	$ 0.33
Repurchase of common stock, authorized amount						$ 40,000			$ 50,000
Period of repurchase of common stock					12 months	12 months
Cumulative number of shares repurchased under all stock repurchase programs								10,320,487
Cumulative cost of shares repurchased under all stock repurchase programs								$ 329,122

Capital Ratios (Details)

Capital Ratios (Details)	Sep. 30, 2019	Dec. 31, 2018
Capital Requirements
Total Capital (to Risk Weighted Assets), Actual Ratio (as a percent)	19.85%	19.74%
CET 1 ratio	17.98%	17.55%
Tier 1 capital (to Average Assets), Actual Ratio (as a percent)	16.06%	15.87%
Tier 1 capital (to Risk Weighted Assets), Actual Ratio (as a percent)	19.20%	19.06%