Prosperity Bancshares (PB) 10-Q 10 Aug 20 2020 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Aug. 03, 2020
Cover [Abstract]
Entity Registrant Name	PROSPERITY BANCSHARES, INC.
Entity Central Index Key	0001068851
Trading Symbol	PB
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding (in shares)		92,660,462
Entity Current Reporting Status	Yes
Entity File Number	001-35388
Entity Incorporation, State or Country Code	TX
Entity Tax Identification Number	74-2331986
Entity Address, Address Line One	Prosperity Bank Plaza
Entity Address, Address Line Two	4295 San Felipe
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77027
City Area Code	281
Local Phone Number	269-7199
Entity Shell Company	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, par value $1.00 per share
Security Exchange Name	NYSE
Document Quarterly Report	true
Document Transition Report	false

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
ASSETS
Cash and due from banks	$ 332,873	$ 573,589
Federal funds sold	568	519
Total cash and cash equivalents	333,441	574,108
Available for sale securities, at fair value	310,045	287,663
Held to maturity securities, at cost (fair value of $7,600,435 and $8,303,851, respectively)	7,407,541	8,282,393
Total securities	7,717,586	8,570,056
Loans held for sale	39,516	80,959
Loans held for investment	18,428,474	17,211,625
Total loans	21,025,173	18,845,346
Less: allowance for credit losses on loans	(324,205)	(87,469)
Loans, net	20,700,968	18,757,877
Accrued interest receivable	94,458	80,797
Goodwill	3,231,964	3,223,671
Core deposit intangibles, net	79,748	86,404
Bank premises and equipment, net	324,975	326,832
Other real estate owned	6,160	6,936
Bank owned life insurance (BOLI)	324,983	321,793
Federal Home Loan Bank of Dallas stock	11,233	83,945
Other assets	141,133	153,289
TOTAL ASSETS	32,966,649	32,185,708
Deposits:
Noninterest-bearing	9,040,257	7,763,894
Interest-bearing	17,112,431	16,435,838
Total deposits	26,152,688	24,199,732
Fed funds purchased and other borrowings	103,131	1,303,730
Securities sold under repurchase agreements	365,335	377,294
Subordinated notes	125,365	125,804
Accrued interest payable	8,144	8,585
Allowance for credit losses on off-balance sheet credit exposure	29,947	5,599
Other liabilities	233,917	194,129
Total liabilities	27,018,527	26,214,873
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS’ EQUITY:
Preferred stock, $1 par value; 20,000,000 shares authorized; none issued or outstanding
Common stock, $1 par value; 200,000,000 shares authorized; 92,660,462 shares issued and outstanding at June 30, 2020; 94,746,019 shares issued and outstanding at December 31, 2019	92,660	94,746
Capital surplus	3,632,847	3,734,519
Retained earnings	2,224,011	2,140,968
Accumulated other comprehensive (loss) income —net unrealized (loss) gain on available for sale securities, net of tax (benefit) expense of $(371) and $160, respectively	(1,396)	602
Total shareholders’ equity	5,948,122	5,970,835
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	32,966,649	32,185,708
Warehouse Purchase Program [Member]
ASSETS
Loans held for investment	2,557,183	1,552,762
Total loans	$ 2,557,183	$ 1,552,762

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Held to maturity securities, fair value	$ 7,600,435	$ 8,303,851
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	92,660,462	94,746,019
Common stock, shares outstanding (in shares)	92,660,462	94,746,019
Accumulated other comprehensive income net unrealized (loss) gain on available for sale securities, tax (benefit) expense	$ (371)	$ 160

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
INTEREST INCOME:
Loans, including fees	$ 242,772	$ 133,525	$ 490,015	$ 263,590
Securities	43,776	53,944	92,058	109,592
Federal funds sold and other earning assets	45	318	758	720
Total interest income	286,593	187,787	582,831	373,902
INTEREST EXPENSE:
Deposits	25,269	26,562	60,287	51,690
Other borrowings	533	5,556	3,465	10,873
Securities sold under repurchase agreements	337	831	1,094	1,590
Subordinated notes	1,499		2,999
Total interest expense	27,638	32,949	67,845	64,153
NET INTEREST INCOME	258,955	154,838	514,986	309,749
PROVISION FOR CREDIT LOSSES	10,000	800	10,000	1,500
NET INTEREST INCOME AFTER PROVISION FOR CREDIT LOSSES	248,955	154,038	504,986	308,249
NONINTEREST INCOME:
Nonsufficient funds (NSF) fees	5,645	7,973	15,088	15,789
Credit card, debit card and ATM card income	7,263	6,480	14,737	12,451
Service charges on deposit accounts	5,790	4,989	11,894	9,987
Trust income	2,242	2,558	4,904	5,153
Mortgage income	1,820	990	3,830	1,712
Brokerage income	584	541	1,234	1,214
Net (loss) gain on sale or write down of assets	(3,945)	2	(4,330)	60
Other	6,276	6,425	12,706	11,736
Total noninterest income	25,675	29,958	60,063	58,102
NONINTEREST EXPENSE:
Salaries and employee benefits	79,109	52,941	156,391	104,014
Net occupancy and equipment	9,190	5,492	18,170	10,958
Credit and debit card, data processing and software amortization	11,690	4,904	23,111	9,477
Regulatory assessments and FDIC insurance	2,601	2,325	4,679	4,699
Core deposit intangibles amortization	3,293	1,265	6,656	2,584
Depreciation	4,598	3,111	9,366	6,215
Communications	3,324	2,183	6,519	4,453
Other real estate expense, net	44	66	(40)	(28)
Merger related expenses	7,474		8,018
Other	13,045	8,534	26,239	17,020
Total noninterest expense	134,368	80,821	259,109	159,392
INCOME BEFORE INCOME TAXES	140,262	103,175	305,940	206,959
PROVISION FOR INCOME TAXES	9,361	20,917	44,191	42,299
NET INCOME	$ 130,901	$ 82,258	$ 261,749	$ 164,660
EARNINGS PER SHARE:
Basic	$ 1.41	$ 1.18	$ 2.80	$ 2.36
Diluted	$ 1.41	$ 1.18	$ 2.80	$ 2.36

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 130,901	$ 82,258	$ 261,749	$ 164,660
Securities available for sale:
Change in unrealized gains (losses) during the period	1,654	716	(2,529)	1,219
Total other comprehensive income (loss)	1,654	716	(2,529)	1,219
Deferred tax (expense) benefit related to other comprehensive income (loss)	(347)	(150)	531	(256)
Other comprehensive income (loss), net of tax	1,307	566	(1,998)	963
Comprehensive income	$ 132,208	$ 82,824	$ 259,751	$ 165,623

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands		Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
BALANCE at Dec. 31, 2018		$ 4,052,824	$ 69,847	$ 2,045,351	$ 1,937,316	$ 310
BALANCE (in shares) at Dec. 31, 2018			69,846,825
Net income		164,660			164,660
Other comprehensive income (loss)		963				963
Common stock issued in connection with the issuance of restricted stock awards, net			$ 13	(13)
Common stock issued in connection with the issuance of restricted stock awards, net (in shares)			13,434
Common stock repurchase		(38,421)	$ (599)	(37,822)
Common stock repurchase (in shares)			(598,828)
Stock based compensation expense		5,149		5,149
Cash dividends declared		(57,280)			(57,280)
BALANCE at Jun. 30, 2019		4,127,895	$ 69,261	2,012,665	2,044,696	1,273
BALANCE (in shares) at Jun. 30, 2019			69,261,431
BALANCE at Mar. 31, 2019		4,109,790	$ 69,846	2,048,156	1,991,081	707
BALANCE (in shares) at Mar. 31, 2019			69,845,925
Net income		82,258			82,258
Other comprehensive income (loss)		566				566
Common stock issued in connection with the issuance of restricted stock awards, net			$ 14	(14)
Common stock issued in connection with the issuance of restricted stock awards, net (in shares)			14,334
Common stock repurchase		(38,421)	$ (599)	(37,822)
Common stock repurchase (in shares)			(598,828)
Stock based compensation expense		2,345		2,345
Cash dividends declared		(28,643)			(28,643)
BALANCE at Jun. 30, 2019		4,127,895	$ 69,261	2,012,665	2,044,696	1,273
BALANCE (in shares) at Jun. 30, 2019			69,261,431
BALANCE at Dec. 31, 2019		5,970,835	$ 94,746	3,734,519	2,140,968	602
BALANCE (in shares) at Dec. 31, 2019			94,746,019
Cumulative change in accounting principle upon adoption of ASU 2016-13 and other at Dec. 31, 2019	[1]	(92,860)			(92,860)
BALANCE AT JANUARY 1, 2020 (AS ADJUSTED FOR CHANGE IN ACCOUNTING STANDARD) at Dec. 31, 2019		5,877,975	$ 94,746	3,734,519	2,048,108	602
Net income		261,749			261,749
Other comprehensive income (loss)		(1,998)				(1,998)
Common stock issued in connection with the issuance of restricted stock awards, net			$ 6	(6)
Common stock issued in connection with the issuance of restricted stock awards, net (in shares)			6,000
Common stock repurchase		(110,061)	$ (2,092)	(107,969)
Common stock repurchase (in shares)			(2,091,557)
Stock based compensation expense		6,303		6,303
Cash dividends declared		(85,846)			(85,846)
BALANCE at Jun. 30, 2020		5,948,122	$ 92,660	3,632,847	2,224,011	(1,396)
BALANCE (in shares) at Jun. 30, 2020			92,660,462
BALANCE at Mar. 31, 2020		5,855,574	$ 92,651	3,629,893	2,135,733	(2,703)
BALANCE (in shares) at Mar. 31, 2020			92,651,712
Net income		130,901			130,901
Other comprehensive income (loss)		1,307				1,307
Common stock issued in connection with the issuance of restricted stock awards, net			$ 9	(9)
Common stock issued in connection with the issuance of restricted stock awards, net (in shares)			8,750
Stock based compensation expense		2,963		2,963
Cash dividends declared		(42,623)			(42,623)
BALANCE at Jun. 30, 2020		$ 5,948,122	$ 92,660	$ 3,632,847	$ 2,224,011	$ (1,396)
BALANCE (in shares) at Jun. 30, 2020			92,660,462
[1]	ASU 2016-13 became effective for the Company on January 1, 2020.

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Retained Earnings [Member]
Cash dividend declared, per share (in dollars per share)	$ 0.46	$ 0.41	$ 0.92	$ 0.82

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 261,749	$ 164,660
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and core deposit intangibles amortization	16,022	8,799
Provision for credit losses	10,000	1,500
Net amortization of premium on investments	17,229	14,196
Net gain on sale of other real estate and repossessed assets	(126)	(231)
Net loss on sale or write down of premises and equipment	1,978
Net loss (gain) on sale or write down of assets	2,352	(60)
Net accretion of discount on loans	(52,748)	(3,020)
Net amortization of premium on deposits	(4,063)
Gain on sale of loans	(3,432)	(1,639)
Proceeds from sale of loans held for sale	215,822	94,650
Originations of loans held for sale	(172,041)	(83,959)
Stock based compensation expense	6,303	5,149
Decrease (increase) in accrued interest receivable and other assets	84,326	(14,998)
Increase in accrued interest payable and other liabilities	54,013	21,442
Net cash provided by operating activities	437,384	206,489
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities and principal paydowns of held to maturity securities	1,064,195	837,003
Purchase of held to maturity securities	(206,563)	(171,656)
Proceeds from maturities and principal paydowns of available for sale securities	4,017,850	7,013,362
Purchase of available for sale securities	(4,042,771)	(7,234,660)
Originations of WPP loans	(17,836,303)
Proceeds from pay-offs of WPP	16,831,882
Net increase in loans held for investment	(1,045,869)	(226,664)
Purchase of bank premises and equipment	(11,893)	(11,738)
Proceeds from sale of bank premises, equipment and other real estate	2,399	2,505
Proceeds from insurance claims	468	2,633
Net cash (used in) provided by investing activities	(1,226,605)	210,785
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in noninterest-bearing deposits	1,276,363	25,121
Net increase (decrease) in interest-bearing deposits	680,656	(394,050)
Net repayments of other short-term borrowings	(1,200,000)	(90,000)
Repayments of other long-term borrowings	(599)	(252)
Net (decrease) increase in securities sold under repurchase agreements	(11,959)	29,105
Repurchase of common stock	(110,061)	(38,421)
Payments of cash dividends	(85,846)	(57,280)
Net cash provided by (used in) financing activities	548,554	(525,777)
NET DECREASE IN CASH AND CASH EQUIVALENTS	(240,667)	(108,503)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	574,108	411,127
CASH AND CASH EQUIVALENTS, END OF PERIOD	333,441	302,624
NONCASH ACTIVITIES:
Acquisition of real estate through foreclosure of collateral	844	1,940
SUPPLEMENTAL INFORMATION:
Income taxes paid		42,850
Interest paid	$ 68,286	$ 63,183

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	1. BASIS OF PRESENTATION The consolidated financial statements include the accounts of Prosperity Bancshares, Inc. ® ® The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for financial information and with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, the statements reflect all adjustments necessary for a fair presentation of the financial position, results of operations and cash flows of the Company on a consolidated basis; and all such adjustments are of a normal recurring nature. These financial statements and the notes thereto should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Operating results for the six-month period ended June 30, 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020 or any other period.

Income Per Common Share

Income Per Common Share	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Income Per Common Share	2. INCOME PER COMMON SHARE The following table illustrates the computation of basic and diluted earnings per share: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Amount Per Share Amount Amount Per Share Amount Amount Per Share Amount Amount Per Share Amount (Amounts in thousands, except per share data) Net income $ 130,901 $ 82,258 $ 261,749 $ 164,660 Basic: Weighted average shares outstanding 92,658 $ 1.41 69,806 $ 1.18 93,514 $ 2.80 69,832 $ 2.36 Diluted: Weighted average shares outstanding 92,658 $ 1.41 69,806 $ 1.18 93,514 $ 2.80 69,832 $ 2.36 As of June 30, 2020, all stock options have been exercised and there are no options outstanding. There were no stock options exercisable during the three and six months ended June 30, 2020 or 2019 that would have had an anti-dilutive effect on the above computation.

New Accounting Standards

New Accounting Standards	6 Months Ended
	Jun. 30, 2020
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
New Accounting Standards	3. NEW ACCOUNTING STANDARDS Accounting Standards Updates (“ASU”) ASU 2020-04, "Reference Rate Reform: Facilitation of the Effects of Reference Rate Reform on Financial Reporting - Accounting Standards Codification (“ASC”) Topic 848 ASU 2020-04 provides optional expedients and exceptions for applying GAAP to loan and lease agreements, derivative contracts, and other transactions affected by the anticipated transition away from LIBOR toward new interest rate benchmarks. The guidance allows for companies to: (i) account for certain contract modifications as a continuation of the existing contract without additional analysis; (ii) continue hedge accounting when certain critical terms of a hedging relationship change and assess effectiveness in ways that disregard certain potential sources of ineffectiveness; and (iii) make a one-time sale and/or transfer of certain debt securities from held-to-maturity to available-for-sale or trading. This ASU is available for adoption effective March 12, 2020 through December 31, 2022. An entity may elect to apply ASU 2020-04 for contract modifications as of January 1, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic within ASU 2020-04, the amendments must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The one-time election to sell and/or transfer debt securities classified as held-to-maturity may be made at any time after March 12, 2020. The Company anticipates this ASU will simplify any modifications it executes between the selected start date (yet to be determined) and December 31, 2022 that are directly related to LIBOR transition by allowing prospective recognition of the continuation of the contract, rather than extinguishment of the old contract resulting in writing off unamortized fees and costs. ASU 2020-04 is not expected to have a significant impact on the Company’s financial statements. ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments (“ASC 326”).” On January 1, 2020 the Company adopted ASU 2016-13 which replaces the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (“CECL”) methodology. CECL requires a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The measurement of CECL is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The Company adopted ASU 2016-13 using the modified-retrospective method for all financial assets measured at amortized cost and off-balance sheet credit exposures. Reporting periods beginning after January 1, 2020 are presented under ASC 326 while prior periods are reported with previously applicable GAAP. Upon adoption of ASU 2016-13, the Company recognized an increase in allowance for credit losses for loans of $108.7 million, of which $102.5 million was related to LegacyTexas Financial Group, Inc. (“LegacyTexas”), which merged into Bancshares on November 1, 2019, and an increase in allowance for credit losses for off-balance sheet credit exposures of $24.4 million, of which $6.3 million was related to LegacyTexas, with a corresponding decrease in retained earnings (pre-tax). Additionally, the Company adopted ASU 2016-13 using the prospective transition approach for financial assets purchased with credit deterioration. The Company recognized an increase in the allowance for credit losses for loans of $131.8 million, of which $130.3 million was related to LegacyTexas, due to the reclass of purchased credit deteriorated discounts as the result of adopting ASU 2016-13. See Note 5 “Loans and Allowance for Credit Losses” for additional information. The Company recognized no allowance for credit losses related to debt securities. See Note 4 “Securities” for additional information. The following table illustrates the impact of adopting ASU 2016-13: January 1, 2020 As Reported Under ASC 326 Pre-ASC 326 Adoption Impact of ASC 326 Adoption (Dollars in thousands) Assets: Loans Construction, land development and other land loans $ 28,729 $ 14,654 $ 14,075 Agriculture and agriculture real estate (includes farmland) 5,768 2,971 2,797 1-4 family (includes home equity) 23,544 15,277 8,267 Commercial real estate (includes multi-family residential) 61,322 12,332 48,990 Commercial and industrial 180,069 40,445 139,624 Consumer and other 28,575 1,790 26,785 Allowance for credit losses on loans $ 328,007 $ 87,469 $ 240,538 Liabilities: Allowance for credit losses on off-balance sheet credit exposures $ 29,947 $ 5,599 $ 24,348

Securities

Securities	6 Months Ended
	Jun. 30, 2020
Investments Debt And Equity Securities [Abstract]
Securities	4. SECURITIES The amortized cost and fair value of investment securities were as follows: June 30, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (Dollars in thousands) Available for Sale States and political subdivisions $ 305 $ 1 $ — $ 306 Collateralized mortgage obligations 265,422 163 (1,870 ) 263,715 Mortgage-backed securities 46,085 626 (687 ) 46,024 Total $ 311,812 $ 790 $ (2,557 ) $ 310,045 Held to Maturity U.S. Treasury securities and obligations of U.S. Government agencies $ 3,977 $ 50 $ — $ 4,027 States and political subdivisions 202,340 7,808 — 210,148 Collateralized mortgage obligations 154,390 2,725 (190 ) 156,925 Mortgage-backed securities 7,046,834 182,947 (446 ) 7,229,335 Total $ 7,407,541 $ 193,530 $ (636 ) $ 7,600,435 December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (Dollars in thousands) Available for Sale States and political subdivisions $ 470 $ 1 $ — $ 471 Collateralized mortgage obligations 235,222 690 (139 ) 235,773 Mortgage-backed securities 51,209 659 (449 ) 51,419 Total $ 286,901 $ 1,350 $ (588 ) $ 287,663 Held to Maturity U.S. Treasury securities and obligations of U.S. Government agencies $ 13,933 $ 58 $ — $ 13,991 States and political subdivisions 238,347 7,632 (189 ) 245,790 Collateralized mortgage obligations 203,470 1,115 (373 ) 204,212 Mortgage-backed securities 7,826,643 48,060 (34,845 ) 7,839,858 Total $ 8,282,393 $ 56,865 $ (35,407 ) $ 8,303,851 The investment securities portfolio is measured for expected credit losses by segregating the portfolio into two general segments and applying the appropriate expected credit losses methodology. Investment securities classified as available for sale or held to maturity are evaluated for expected credit losses under Financial Accounting Standards Board (“FASB”): ASC 326 , “Financial Instruments – Credit Losses.” Available for sale securities . For available for sale securities in an unrealized loss position, the amount of the expected credit losses recognized in earnings depends on whether an entity intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss. If an entity intends to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the expected credit losses will be recognized in earnings equal to the entire difference between the investment’s amortized cost basis and its fair value at the balance sheet date. If an entity does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis less any current-period loss, the expected credit losses will be separated into the amount representing the credit-related portion of the impairment loss (“credit loss”) and the noncredit portion of the impairment loss (“noncredit portion”). The amount of the total expected credit losses related to the credit loss is determined based on the difference between the present value of cash flows expected to be collected and the amortized cost basis and such difference is recognized in earnings. The amount of the total expected credit losses related to the noncredit portion is recognized in other comprehensive income, net of applicable taxes. The previous amortized cost basis less the expected credit losses recognized in earnings will become the new amortized cost basis of the investment. A s of June 30, 2020 , management does not have the intent to sell any of the securities classified as available for sale before a recovery of cost. In addition, management believes it is more likely than not that the Company will not be required to sell any of its investment securities before a recovery of cost. The unrealized losses are largely due to changes in market interest rates and spread relationships since the time the underlying securities were purchased . The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality. Accordingly, as of June 30, 2020 , management believes that there is no potential for credit losses on available for sale securities. Held to maturity securities . The Company’s held to maturity investments include mortgage-related bonds issued by either the Government National Mortgage Corporation (“Ginnie Mae”), Federal National Mortgage Association (“Fannie Mae”) or Federal Home Loan Mortgage Corporation (“Freddie Mac”). Ginnie Mae issued securities are explicitly guaranteed by the U.S. government, while Fannie Mae and Freddie Mac issued securities are fully guaranteed by those respective United States government-sponsored agencies, and conditionally guaranteed by the full faith and credit of the United States. The Company’s held to maturity securities also include taxable and tax-exempt municipal securities issued primarily by school districts, utility districts and municipalities located in Texas. The Company’s investment in municipal securities is exposed to credit risk. The securities are highly rated by major rating agencies and regularly reviewed by management. A significant portion are guaranteed or insured by either the Texas Permanent School Fund, Assured Guaranty or Build America Mutual. As of June 30, 2020, the Company’s municipal securities represent 2.6% of the securities portfolio. Management has the ability and intent to hold the securities classified as held to maturity until they mature, at which time the Company will receive full value for the securities. Accordingly, as of June 30, 2020, management believes that there is no potential for material credit losses on held to maturity securities. Securities with unrealized losses, segregated by length of time, that have been in a continuous loss position were as follows: June 30, 2020 Less than 12 Months 12 Months or More Total Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses (Dollars in thousands) Available for Sale Collateralized mortgage obligations $ 189,617 $ (1,859 ) $ 1,628 $ (11 ) $ 191,245 $ (1,870 ) Mortgage-backed securities 17,121 (400 ) 13,755 (287 ) 30,876 (687 ) Total $ 206,738 $ (2,259 ) $ 15,383 $ (298 ) $ 222,121 $ (2,557 ) Held to Maturity Collateralized mortgage obligations $ 40,895 $ (190 ) — — 40,895 (190 ) Mortgage-backed securities 37,652 (438 ) 1,443 (8 ) 39,095 (446 ) Total $ 78,547 $ (628 ) $ 1,443 $ (8 ) $ 79,990 $ (636 ) December 31, 2019 Less than 12 Months 12 Months or More Total Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses (Dollars in thousands) Available for Sale Collateralized mortgage obligations $ 50,245 $ (136 ) $ 1,818 $ (3 ) $ 52,063 $ (139 ) Mortgage-backed securities 34,901 (449 ) 10 — 34,911 (449 ) Total $ 85,146 $ (585 ) $ 1,828 $ (3 ) $ 86,974 $ (588 ) Held to Maturity States and political subdivisions $ 58,329 $ (183 ) $ 3,241 $ (6 ) $ 61,570 $ (189 ) Collateralized mortgage obligations 54,890 (373 ) — — 54,890 (373 ) Mortgage-backed securities 947,314 (3,017 ) 3,110,765 (31,828 ) 4,058,079 (34,845 ) Total $ 1,060,533 $ (3,573 ) $ 3,114,006 $ (31,834 ) $ 4,174,539 $ (35,407 ) At June 30, 2020 and December 31, 2019, there were 29 securities and 138 securities, respectively, in an unrealized loss position for 12 months or more. The amortized cost and fair value of investment securities at June 30, 2020, by contractual maturity, are shown below. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations at any time with or without call or prepayment penalties. Held to Maturity Available for Sale Amortized Cost Fair Value Amortized Cost Fair Value (Dollars in thousands) Due in one year or less $ 29,087 $ 29,280 $ 305 $ 306 Due after one year through five years 114,383 119,288 — — Due after five years through ten years 56,229 58,779 — — Due after ten years 6,618 6,828 — — Subtotal 206,317 214,175 305 306 Mortgage-backed securities and collateralized mortgage obligations 7,201,224 7,386,260 311,507 309,739 Total $ 7,407,541 $ 7,600,435 $ 311,812 $ 310,045 The Company recorded no gain or loss on the sale of securities for the three and six months ended June 30, 2020 and 2019. As of June 30, 2020, the Company did not own any non-agency collateralized mortgage obligations. At June 30, 2020 and December 31, 2019, the Company did not own securities of any one issuer (other than the U.S. government and its agencies) for which aggregate adjusted cost exceeded 10% of the consolidated shareholders’ equity at such respective dates. Securities with an amortized cost of $5.66 billion and $5.98 billion and a fair value of $5.80 billion and $5.99 billion at June 30, 2020 and December 31, 2019, respectively, were pledged to collateralize public deposits and for other purposes required or permitted by law.

Loans and Allowance for Credit

Loans and Allowance for Credit Losses	6 Months Ended
	Jun. 30, 2020
Receivables [Abstract]
Loans and Allowance for Credit Losses	5. LOANS AND ALLOWANCE FOR CREDIT LOSSES The loan portfolio consists of various types of loans and is categorized by major type as follows: June 30, 2020 December 31, 2019 (Dollars in thousands) Residential mortgage loans held for sale $ 39,516 $ 80,959 Commercial and industrial 4,227,102 3,205,595 Real estate: Construction, land development and other land loans 2,033,037 2,064,167 1-4 family residential (includes home equity) 4,582,554 4,306,452 Commercial real estate (includes multi-family residential) 6,550,086 6,556,285 Farmland 429,963 495,558 Agriculture 182,731 185,297 Consumer and other 423,001 398,271 Total loans held for investment, excluding Warehouse Purchase Program 18,428,474 17,211,625 Warehouse Purchase Program 2,557,183 1,552,762 Total loans, including Warehouse Purchase Program $ 21,025,173 $ 18,845,346 Concentrations of Credit. Most of the Company’s lending activity occurs within the states of Texas and Oklahoma. Commercial real estate loans, 1-4 family residential loans and construction, land development and other land loans make up 71.3% of the Company’s total loan portfolio, excluding Warehouse Purchase Program loans, at June 30, 2020. As of June 30, 2020 and December 31, 2019, excluding Warehouse Purchase Program loans, there were no concentrations of loans related to any single industry in excess of 10% Related Party Loans. As of June 30, 2020 and December 31, 2019, loans outstanding to directors, officers and their affiliates totaled $4.9 million and $4.2 million, respectively. All transactions between the Company and such related parties are conducted in the ordinary course of business and made on the same terms and conditions as similar transactions with unaffiliated persons. An analysis of activity with respect to these related party loans is as follows: As of and for the six months ended June 30, 2020 As of and for the year ended December (Dollars in thousands) Beginning balance on January 1 $ 4,152 $ 1,923 New loans 810 1 Transfers — 2,500 Repayments (109 ) (272 ) Ending balance $ 4,853 $ 4,152 Nonperforming Assets and Nonaccrual and Past Due Loans. The Company has several procedures in place to assist it in maintaining the overall quality of its loan portfolio. The Company has established underwriting guidelines to be followed by its officers, including requiring appraisals on loans collateralized by real estate. The Company also monitors its delinquency levels for any negative or adverse trends. Nevertheless, the Company’s loan portfolio could become subject to increasing pressures from deteriorating borrower credit due to general economic conditions. The Company generally places a loan on nonaccrual status and ceases accruing interest when the payment of principal or interest is delinquent for 90 days, or earlier in some cases, unless the loan is in the process of collection and the underlying collateral fully supports the carrying value of the loan. With respect to potential problem loans, an evaluation of the borrower’s overall financial condition is made to determine the need, if any, for possible writedowns or appropriate additions to the allowance for credit losses. An aging analysis of past due loans, segregated by category of loan, is presented below: June 30, 2020 Loans Past Due and Still Accruing 30-89 Days 90 or More Days Total Past Due Loans Nonaccrual Loans Current Loans Total Loans (Dollars in thousands) Construction, land development and other land loans $ 13,846 $ 8,287 $ 22,133 $ 2,243 $ 2,008,661 $ 2,033,037 Warehouse Purchase Program loans — — — — 2,557,183 2,557,183 Agriculture and agriculture real estate (includes farmland) 3,008 — 3,008 769 608,917 612,694 1-4 family (includes home equity) (1) 9,098 43 9,141 29,642 4,583,287 4,622,070 Commercial real estate (includes multi-family residential) 7,881 319 8,200 15,129 6,526,757 6,550,086 Commercial and industrial 12,085 25 12,110 15,057 4,199,935 4,227,102 Consumer and other 3,915 17 3,932 64 419,005 423,001 Total $ 49,833 $ 8,691 $ 58,524 $ 62,904 $ 20,903,745 $ 21,025,173 December 31, 2019 Loans Past Due and Still Accruing 30-89 Days 90 or More Days Total Past Due Loans Nonaccrual Loans Current Loans Total Loans (Dollars in thousands) Construction, land development and other land loans $ 16,470 $ — $ 16,470 $ 1,142 $ 2,046,555 $ 2,064,167 Warehouse Purchase Program loans — — — — 1,552,762 1,552,762 Agriculture and agriculture real estate (includes farmland) 466 — 466 103 680,286 680,855 1-4 family (includes home equity) (1) 43,884 441 44,325 24,413 4,318,673 4,387,411 Commercial real estate (includes multi-family residential) 10,669 — 10,669 12,714 6,532,902 6,556,285 Commercial and industrial 7,249 — 7,249 16,809 3,181,537 3,205,595 Consumer and other 1,708 — 1,708 62 396,501 398,271 Total $ 80,446 $ 441 $ 80,887 $ 55,243 $ 18,709,216 $ 18,845,346 (1) Includes $39.5 million and $81.0 million of residential mortgage loans held for sale at June 30, 2020 and December 31, 2019, respectively. The following table presents information regarding nonperforming assets as of the dates indicated: June 30, 2020 December 31, 2019 (Dollars in thousands) Nonaccrual loans (1) (2) $ 62,904 $ 55,243 Accruing loans 90 or more days past due 8,691 441 Total nonperforming loans 71,595 55,684 Repossessed assets 187 323 Other real estate 6,160 6,936 Total nonperforming assets $ 77,942 $ 62,943 Nonperforming assets to total loans and other real estate 0.37 % 0.33 % Nonperforming assets to total loans, excluding Warehouse Purchase Program loans, and other real estate 0.42 % 0.36 % (1) Includes troubled debt restructurings of $13.6 million as of both June 30, 2020 and December 31, 2019. (2) There were no nonperforming or troubled debt restructurings of warehouse lines of credit or Warehouse Purchase Program loans for the periods presented. The Company had $77.9 million in nonperforming assets at June 30, 2020 compared with $62.9 million at December 31, 2019. Nonperforming assets were 0.37% of total loans and other real estate at June 30, 2020 compared with 0.33% of total loans and other real estate at December 31, 2019. If interest on nonaccrual loans had been accrued under the original loan terms, approximately $1.4 million and $1.2 million would have been recorded as income for the six months ended June 30, 2020 and 2019, respectively. The Company had $62.9 million in nonaccrual loans at June 30, 2020 compared with $37.3 million at June 30, 2019. Acquired Loans. Acquired loans were preliminarily recorded at fair value based on a discounted cash flow valuation methodology that considers, among other things, interest rates, projected default rates, loss given default, and recovery rates. During the valuation process, the Company identified purchased credit deteriorated (“PCD”) and Non-PCD loans in the acquired loan portfolios. Loans acquired with evidence of credit quality deterioration at acquisition for which it was probable that the Company would not be able to collect all contractual amounts due were accounted for as PCD. PCD loan identification considers the following factors: payment history and past due status, debt service coverage, loan grading, collateral values and other factors that may indicate deterioration of credit quality since origination. Non-PCD loan identification considers the following factors: account types, remaining terms, annual interest rates or coupons, current market rates, interest types, past delinquencies, timing of principal and interest payments, loan to value ratios, loss exposures and remaining balances. Accretion of purchased yield discounts on PCD loans will be based on future cash flows, taking into account contractual maturities. Accretion of purchased discounts on Non-PCD loans will be recognized on a level-yield basis based on contractual maturity of individual loans. PCD Loans. The recorded investment in PCD loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below. The outstanding balance represents the total amount owed as of June 30, 2020 and December 31, 2019 . June 30, 2020 December 31, 2019 (Dollars in thousands) PCD loans: Outstanding balance $ 290,189 $ 410,785 Discount (1) (22,565 ) (167,320 ) (2) Recorded investment $ 267,624 $ 243,465 (1) ASU 2016-13 became effective for the Company on January 1, 2020. (2) Includes $131.8 million in PCD loans credit discount. Changes in the accretable yield for acquired PCD loans for the three and six months ended June 30, 2020 and 2019 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (Dollars in thousands) Balance at beginning of period $ 29,460 $ 1,234 $ 35,654 $ 1,534 Adjustments (274 ) 17 (449 ) 36 Accretion charge-offs (354 ) — (354 ) — Accretion (6,267 ) (347 ) (12,286 ) (666 ) Balance at June 30, $ 22,565 $ 904 $ 22,565 $ 904 Income recognition on PCD loans is subject to the timing and amount of future cash flows. PCD loans for which the Company is accruing interest income are not considered non-performing or impaired. The adoption of ASU 2016-13, “ Financial Instruments-Credit-Losses (ASC Topic 326) – Measurement of Credit Losses on Financial Instruments Non-PCD Loans. The recorded investment in Non-PCD loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below. The outstanding balance represents the total amount owed as of June 30, 2020 and December 31, 2019. June 30, 2020 December 31, 2019 (Dollars in thousands) Non-PCD loans: Outstanding balance $ 5,117,679 $ 6,102,540 Discount (69,860 ) (110,130 ) Recorded investment $ 5,047,819 $ 5,992,410 Changes in the discount accretion for Non-PCD loans for the three and six months ended June 30, 2020 and 2019 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (Dollars in thousands) Balance at beginning of period $ 87,613 $ 13,359 $ 110,130 $ 14,833 Adjustments 312 — 312 — Accretion charge-offs (66 ) — (120 ) — Accretion (17,999 ) (880 ) (40,462 ) (2,354 ) Balance at June 30, $ 69,860 $ 12,479 $ 69,860 $ 12,479 Credit Quality Indicators. As part of the on-going monitoring of the credit quality of the Company’s loan portfolio and methodology for calculating the allowance for credit losses, management assigns and tracks loan grades to be used as credit quality indicators. The following is a general description of the loan grades used: Grade 1— Credits in this category have risk potential that is virtually nonexistent. These loans may be secured by insured certificates of deposit, insured savings accounts, U.S. Government securities and highly rated municipal bonds. Grade 2— Credits in this category are of the highest quality. These borrowers represent top rated companies and individuals with unquestionable financial standing with excellent global cash flow coverage, net worth, liquidity and collateral coverage. Grade 3— Credits in this category are not immune from risk but are well protected by the collateral and paying capacity of the borrower. These loans may exhibit a minor unfavorable credit factor, but the overall credit is sufficiently strong to minimize the possibility of loss. Grade 4— Credits in this category are considered to be of acceptable credit quality with moderately greater risk than Grade 3 and receiving closer monitoring. Loans in this category have sources of repayment that remain sufficient to preclude a larger than normal probability of default and secondary sources are likewise currently of sufficient quantity, quality, and liquidity to protect the Company against loss of principal and interest. These borrowers have specific risk factors, but the overall strength of the credit is acceptable based on other mitigating credit and/or collateral factors and can repay the debt in the normal course of business. Grade 5— Credits in this category constitute an undue and unwarranted credit risk; however, the factors do not rise to a level of substandard. These credits have potential weaknesses and/or declining trends that, if not corrected, could expose the Company to risk at a future date. These loans are monitored on the Company’s internally-generated watch list and evaluated on a quarterly basis. Grade 6— Credits in this category are considered “substandard” but “non-impaired” loans in accordance with regulatory guidelines. Loans in this category have well-defined weakness that, if not corrected, could make default of principal and interest possible. Loans in this category are still accruing interest and may be dependent upon secondary sources of repayment and/or collateral liquidation. Grade 7— Credits in this category are deemed “substandard” and “impaired” pursuant to regulatory guidelines. As such, the Company has determined that it is probable that less than 100% of the contractual principal and interest will be collected. These loans are individually evaluated for a specific reserve and will typically have the accrual of interest stopped. Grade 8— Credits in this category include “doubtful” loans in accordance with regulatory guidance. Such loans are no longer accruing interest and factors indicate a loss is imminent. These loans are also deemed “impaired.” While a specific reserve may be in place while the loan and collateral is being evaluated, these loans are typically charged down to an amount the Company estimates is collectible. Grade 9— Credits in this category are deemed a “loss” in accordance with regulatory guidelines and have been charged off or charged down. The Company may continue collection efforts and may have partial recovery in the future. The following table presents loans by risk grade and category of loan at June 30, 2020. Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Loans Total (Dollars in thousands) Construction, Land Development and Other Land Loans Grade 1 $ — $ — $ — $ — $ — $ 27 $ — $ — $ 27 Grade 2 — — — 88 132 281 — — 501 Grade 3 345,184 702,893 417,348 116,076 38,311 74,496 120,229 1,637 1,816,174 Grade 4 6,435 16,742 33,221 113,509 7,056 13,771 9,682 — 200,416 Grade 5 — — — 4 — 2,910 — — 2,914 Grade 6 — — — — — 2,202 — — 2,202 Grade 7 — — 1,118 — — 390 734 — 2,242 Grade 8 — — — — — — — — — Grade 9 — — — — — — — — — PCD Loans — 1,305 — 397 — 6,859 — — 8,561 Total $ 351,619 $ 720,940 $ 451,687 $ 230,074 $ 45,499 $ 100,936 $ 130,645 $ 1,637 $ 2,033,037 Agriculture and Agriculture Real Estate (includes Farmland) Grade 1 $ 695 $ 380 $ 308 $ 255 $ 103 $ 526 $ 10,100 $ — $ 12,367 Grade 2 10 — — 355 — 1,591 40 — 1,996 Grade 3 68,790 90,926 71,576 49,393 57,106 110,608 75,452 1,252 525,103 Grade 4 8,750 9,697 4,798 3,083 5,099 22,535 5,912 — 59,874 Grade 5 1,654 3,419 1,130 — — 648 2,043 — 8,894 Grade 6 1,468 — 59 — 186 184 — — 1,897 Grade 7 — 353 32 — 4 357 — — 746 Grade 8 — — — — — — — — — Grade 9 — — — — — — — — — PCD Loans — 217 — — — 1,294 — 306 1,817 Total $ 81,367 $ 104,992 $ 77,903 $ 53,086 $ 62,498 $ 137,743 $ 93,547 $ 1,558 $ 612,694 1-4 Family (includes Home Equity) (1) Grade 1 $ 98 $ — $ — $ — $ — $ — $ — $ — $ 98 Grade 2 — 71 121 728 260 11,068 1,335 — 13,583 Grade 3 644,503 909,952 610,756 532,702 512,549 1,114,277 139,042 5,022 4,468,803 Grade 4 1,980 12,884 18,229 13,841 10,496 38,260 2,722 138 98,550 Grade 5 — 164 — 1,258 232 4,082 — — 5,736 Grade 6 85 42 3 328 — 2,165 — 32 2,655 Grade 7 — 1,746 986 2,887 3,159 13,590 3,587 — 25,955 Grade 8 — — — — — 99 — — 99 Grade 9 — — — — — — — — — PCD Loans — — — — 251 5,300 1,040 — 6,591 Total $ 646,666 $ 924,859 $ 630,095 $ 551,744 $ 526,947 $ 1,188,841 $ 147,726 $ 5,192 $ 4,622,070 Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Loans Total (Dollars in thousands) Commercial Real Estate (includes Multi-Family Residential) Grade 1 $ — $ — $ — $ — $ — $ — $ — $ — $ — Grade 2 5,743 2,008 — 7,480 193 4,980 — — 20,404 Grade 3 188,791 1,035,743 1,022,056 1,037,919 641,974 1,432,384 73,808 40,429 5,473,104 Grade 4 13,295 34,582 114,906 149,851 157,957 391,781 13,272 345 875,989 Grade 5 — — 2,164 12,888 12,575 14,521 — — 42,148 Grade 6 7,928 175 1,250 26 3,218 8,165 1,500 — 22,262 Grade 7 21 — — 16 14,796 210 — — 15,043 Grade 8 — — — — — — — — — Grade 9 — — — — — — — — — PCD Loans — 15,329 5,094 27,440 — 53,273 — — 101,136 Total $ 215,778 $ 1,087,837 $ 1,145,470 $ 1,235,620 $ 830,713 $ 1,905,314 $ 88,580 $ 40,774 $ 6,550,086 Commercial and Industrial Grade 1 $ 1,379,014 $ 8,123 $ 7,034 $ 3,487 $ 1,597 $ 7,345 $ 20,344 $ 23 $ 1,426,967 Grade 2 999 155 1,137 1,530 1,442 1,132 21,124 62,772 90,291 Grade 3 173,841 331,439 226,143 116,920 111,163 185,271 792,523 263,799 2,201,099 Grade 4 10,170 53,041 22,132 29,046 11,293 50,492 66,940 28,947 272,061 Grade 5 3,057 16,813 476 157 297 2,359 7,568 114 30,841 Grade 6 101 243 2,492 206 1,266 2,254 23,442 650 30,654 Grade 7 — 570 367 110 649 12,963 31,650 1,449 47,758 Grade 8 — — — — 10 — — — 10 Grade 9 — — — — — — — — — PCD Loans 790 28,991 8,280 11,746 3,582 1,715 49,350 22,967 127,421 Total $ 1,567,972 $ 439,375 $ 268,061 $ 163,202 $ 131,299 $ 263,531 $ 1,012,941 $ 380,721 $ 4,227,102 Consumer and Other Grade 1 $ 26,314 $ 10,550 $ 5,938 $ 4,882 $ 2,519 $ 6,334 $ 1,518 $ 3 $ 58,058 Grade 2 2,345 10,763 418 38,306 233 1,402 1,185 — 54,652 Grade 3 33,702 54,277 36,175 18,500 7,721 30,553 75,869 338 257,135 Grade 4 478 4,219 964 77 109 2,084 11,057 4 18,992 Grade 5 — — 68 18 — — 10,402 — 10,488 Grade 6 — 1,534 — — — — — — 1,534 Grade 7 — 32 8 6 (5 ) 3 — — 44 Grade 8 — — — — — — — — — Grade 9 — — — — — — — — — PCD Loans — — — 1,880 — 3,800 16,418 — 22,098 Total $ 62,839 $ 81,375 $ 43,571 $ 63,669 $ 10,577 $ 44,176 $ 116,449 $ 345 $ 423,001 Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Loans Total (Dollars in thousands) Warehouse Purchase Program Grade 1 $ — $ — $ — $ — $ — $ — $ — $ — $ — Grade 2 — — — — — — — — — Grade 3 2,557,183 — — — — — — — 2,557,183 Grade 4 — — — — — — — — — Grade 5 — — — — — — — — — Grade 6 — — — — — — — — — Grade 7 — — — — — — — — — Grade 8 — — — — — — — — — Grade 9 — — — — — — — — — PCD Loans — — — — — — — — — Total $ 2,557,183 $ — $ — $ — $ — $ — $ — $ — $ 2,557,183 Total Grade 1 $ 1,406,121 $ 19,053 $ 13,280 $ 8,624 $ 4,219 $ 14,232 $ 31,962 $ 26 $ 1,497,517 Grade 2 9,097 12,997 1,676 48,487 2,260 20,454 23,684 62,772 181,427 Grade 3 4,011,994 3,125,230 2,384,054 1,871,510 1,368,824 2,947,589 1,276,923 312,477 17,298,601 Grade 4 41,108 131,165 194,250 309,407 192,010 518,923 109,585 29,434 1,525,882 Grade 5 4,711 20,396 3,838 14,325 13,104 24,520 20,013 114 101,021 Grade 6 9,582 1,994 3,804 560 4,670 14,970 24,942 682 61,204 Grade 7 21 2,701 2,511 3,019 18,603 27,513 35,971 1,449 91,788 Grade 8 — — — — 10 99 — — 109 Grade 9 — — — — — — — — — PCD Loans 790 45,842 13,374 41,463 3,833 72,241 66,808 23,273 267,624 Total $ 5,483,424 $ 3,359,378 $ 2,616,787 $ 2,297,395 $ 1,607,533 $ 3,640,541 $ 1,589,888 $ 430,227 $ 21,025,173 (1) Includes $39.5 million of residential mortgage loans held for sale at June 30, 2020. Allowance for Credit Losses on Loans. The allowance for credit losses is established through charges to earnings in the form of a provision for credit losses. Management has established an allowance for credit losses which it believes is adequate as of June 30, 2020 for estimated losses in the Company’s loan portfolio. The amount of the allowance for credit losses is affected by the following: (1) charge-offs of loans that occur when loans are deemed uncollectible and decrease the allowance, (2) recoveries on loans previously charged off that increase the allowance and (3) provisions for credit losses charged to earnings that increase the allowance or provision releases returned to earnings that decrease the allowance. Based on an evaluation of the loan portfolio and consideration of the factors listed below, management presents a quarterly review of the allowance for credit losses to the Bank’s Board of Directors, indicating any change in the allowance since the last review and any recommendations as to adjustments in the allowance. Although management believes it uses the best information available to make determinations with respect to the allowance for credit losses, future adjustments may be necessary if economic conditions or the borrower’s performance differ from the assumptions used in making the initial determinations. The Company’s allowance for credit losses on loans consists of two components: (1) a specific valuation allowance based on probable losses on specifically identified loans and (2) a general valuation allowance based on historical loan loss experience, general economic conditions and other qualitative risk factors both internal and external to the Company. In setting the specific valuation allowance, the Company follows a loan review program to evaluate the credit risk in the total loan portfolio and assigns risk grades to each loan. Through this loan review process, the Company maintains an internal list of impaired loans, which along with the delinquency list of loans, helps management assess the overall quality of the loan portfolio and the adequacy of the allowance for credit losses. All loans that have been identified as impaired are reviewed on a quarterly basis in order to determine whether a specific reserve is required. For certain impaired loans, the Company allocates a specific loan loss reserve primarily based on the value of the collateral securing the impaired loan in accordance with ASC Topic 326-20, “ Financial Instruments - Credit Losses . ” The specific reserves are determined on an individual loan basis. Loans for which specific reserves are provided are excluded from the general valuation allowance described below. In connection with this review of the loan portfolio, the Company considers risk elements attributable to particular loan types or categories in assessing the quality of individual loans. Some of the risk elements include: • for 1-4 family residential mortgage loans, the borrower’s ability to repay the loan, including a consideration of the debt to income ratio and employment and income stability, the loan to value ratio, and the age, condition and marketability of collateral; • for commercial real estate loans and multifamily residential loans, the debt service coverage ratio (income from the property in excess of operating expenses compared to loan payment requirements), operating results of the owner in the case of owner-occupied properties, the loan to value ratio, the age and condition of the collateral and the volatility of income, property value and future operating results typical of properties of that type; • for construction, land development and other land loans, the perceived feasibility of the project including the ability to sell developed lots or improvements constructed for resale or the ability to lease property constructed for lease, the quality and nature of contracts for presale or prelease, if any, experience and ability of the developer and loan to value ratio; • for commercial and industrial loans, the operating results of the commercial, industrial or professional enterprise, the borrower’s business, professional and financial ability and expertise, the specific risks and volatility of income and operating results typical for businesses in that category and the value, nature and marketability of collateral; • for the Warehouse Purchase Program, the capitalization and liquidity of the mortgage banking client, the operating experience, the client’s satisfactory underwriting of purchased loans and the consistent timeliness by client of loan resale to investors; • for agriculture real estate loans, the experience and financial capability of the borrower, projected debt service coverage of the operations of the borrower and loan to value ratio; and • for non-real estate agriculture loans, the operating results, experience and financial capability of the borrower, historical and expected market conditions and the value, nature and marketability of collateral. In addition, for each category, the Company considers secondary sources of income and the financial strength and credit history of the borrower and any guarantors. In determining the amount of the general valuation allowance, management considers factors such as historical lifetime loan loss experience, concentration risk of specific loan types, the volume, growth and composition of the Company’s loan portfolio, current economic conditions and reasonable and supportable forecasted economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the Company’s loan portfolio through its internal loan review process, general economic conditions and other qualitative risk factors both internal and external to the Company and other relevant factors in accordance with ASC Topic 326, “ Financial Instruments – Credit Losses.” The following table details activity in the allowance for credit losses on loans by category of loan for the three and six months ended June 30, 2020 and 2019. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. Construction, Land Development and Other Land Loans Agriculture and Agriculture Real Estate (includes Farmland) 1-4 Family (includes Home Equity) Commercial Real Estate (includes Multi-Family Residential) Commercial and Industrial Consumer and Other Total (Dollars in thousands) Allowance for credit losses: Three Months Ended Balance March 31, 2020 $ 28,741 $ 5,769 $ 23,539 $ 61,403 $ 180,097 $ 27,657 $ 327,206 Provision for credit losses 11,115 1,126 9,533 16,804 (18,007 ) (10,571 ) 10,000 Charge-offs — (32 ) (145 ) — (12,678 ) (1,121 ) (13,976 ) Recoveries 6 35 94 — 472 368 975 Net charge-offs 6 3 (51 ) — (12,206 ) (753 ) (13,001 ) Balance June 30, 2020 $ 39,862 $ 6,898 $ 33,021 $ 78,207 $ 149,884 $ 16,333 $ 324,205 Six Months Ended Beginning balance, prior to adoption of ASC 326 $ 14,654 $ 2,971 $ 15,277 $ 12,332 $ 40,445 $ 1,790 $ 87,469 Impact of adoption ASC 326 14,075 2,797 8,267 48,990 139,624 26,785 240,538 Provision for credit losses 11,115 1,126 9,533 16,804 (18,007 ) (10,571 ) 10,000 Charge-offs — (62 ) (175 ) — (13,289 ) (2,437 ) (15,963 ) Recoveries 18 66 119 81 1,111 766 2,161 Net charge-offs 18 4 (56 ) 81 (12,178 ) (1,671 ) (13,802 ) Balance June 30, 2020 $ 39,862 $ 6,898 $ 33,021 $ 78,207 $ 149,884 $ 16,333 $ 324,205 Allowance for credit losses: Three Months Ended Balance March 31, 2019 $ 16,192 $ 3,284 $ 14,455 $ 11,590 $ 39,059 $ 1,511 $ 86,091 Provision for credit losses (299 ) 578 (61 ) 575 (710 ) 717 800 Charge-offs (19 ) (54 ) (16 ) — (125 ) (905 ) (1,119 ) Recoveries 12 8 5 1 953 255 1,234 Net charge-offs (7 ) (46 ) (11 ) 1 828 (650 ) 115 Balance June 30, 2019 $ 15,886 $ 3,816 $ 14,383 $ 12,166 $ 39,177 $ 1,578 $ 87,006 Six Months Ended Balance December 31, 2018 $ 15,582 $ 3,693 $ 14,135 $ 11,220 $ 40,223 $ 1,587 $ 86,440 Provision for credit losses 311 (1,109 ) 256 944 (155 ) 1,253 1,500 Charge-offs (63 ) (64 ) (22 ) — (2,082 ) (1,797 ) (4,028 ) Recoveries 56 1,296 14 2 1,191 535 3,094 Net charge-offs (7 ) 1,232 (8 ) 2 (891 ) (1,262 ) (934 ) Balance June 30, 2019 $ 15,886 $ 3,816 $ 14,383 $ 12,166 $ 39,177 $ 1,578 $ 87,006 Allowance for Credit Losses on Off-Balance Sheet Credit Exposures. The allowance also includes estimates of expected credit losses over the contractual period in which there is exposure to credit risk via a contractual obligation to extend credit, unless that obligation is unconditionally cancellable by the Company. The allowance for credit losses on off-balance sheet exposures is adjusted as a provision for credit loss expense. The estimate includes consideration of the likelihood that funding will occur and an estimate of expected credit losses on the commitments expected to fund. The estimate of commitments expected to fund is informed by historical analysis looking at utilization rates. The expected credit loss rates applied to the commitments expected to fund is informed by the general valuation allowance utilized for outstanding balances with the same underlying assumptions and drivers. As of June 30, 2020, the Company had $29.9 million in allowance for credit losses on off-balance sheet credit exposure, compared with $5.6 million as of December 31, 2019. This allowance for credit losses on off-balance sheet credit exposure is a separate line item on the Company’s consolidated balance sheet. As of June 30, 2020, the Company had $1.77 billion in commitments expected to fund. Troubled Debt Restructurings. The restructuring of a loan is considered a “troubled debt restructuring” if both (1) the borrower is experiencing financial difficulties and (2) the creditor has granted a concession. Concessions may include interest rate reductions or below market interest rates, principal forgiveness, restructuring amortization schedules and other actions intended to minimize potential losses. Under ASC Topic 310-40 “ the Company evaluates all loan modifications to identify whether the restructuring constitutes a troubled debt restructuring. As of June 30, 2020 and 2019, respectively, the Company had $13.6 million and $14.3 million, in outstanding troubled debt restructurings. The following table presents information regarding the recorded investment of loans that were modified as troubled debt restructurings during the six months ended June 30, 2020 and 2019. Six Months Ended June 30, 2020 2019 Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment (Dollars in thousands) Troubled Debt Restructurings Construction, land development and other land loans — $ — $ — — $ — $ — Agriculture and agriculture real estate (includes farmland) — — — — — — 1-4 Family (includes home equity) 1 23 13 — — — Commercial real estate (includes multi-family residential) — — — — — — Commercial and industrial — — — 1 14,783 14,258 Consumer and other — — — — — — Total 1 $ 23 $ 13 1 $ 14,783 $ 14,258 As of June 30, 2020, there have been no defaults on any loans that were modified as troubled debt restructurings during the preceding twelve months. Default is determined at 90 or more days past due. The modifications generally relate to extending the amortization periods of the loans, which includes loans modified during bankruptcy. For the six months ended June 30, 2020, the Company added one loan totaling $23 thousand as a new troubled debt restructuring, of which $13 thousand remained outstanding at June 30, 2020. For the six months ended June 30, 2019, the Company added one loan totaling $14.8 million as a new troubled debt restructuring, of which $14.3 million remained outstanding at June 30, 2019. The Company did not grant principal reductions on any restructured loans at the time of modification. These modifications did not have a material impact on the Company’s determination of the allowance for credit losses. Under the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”), banks may elect to deem that loan modifications do not result in troubled debt restructurings if they are (1) related to the novel strain of coronavirus disease (“COVID-19”); (2) executed on a loan that was not more than 30 days past due as of December 31, 2019; and (3) executed between March 1, 2020, and the earlier of (A) 60 days after the date of termination of the COVID-19 national emergency declaration by the President of the United States or (B) December 31, 2020. Additionally, other short-term modifications made on a good faith basis in response to COVID-19 to borrowers who were current prior to any relief are not troubled debt restructurings under ASC Subtopic 310-40 and federal banking agencies’ interagency guidance. These modifications include short-term (e.g., up to six months) modifications such as payment deferrals, fee waivers, extensions of repayment terms, or delays in payment that are insignificant. Borrowers considered current are those that are less than 30 days past due on their contractual payments at the time a modification program is implemented. T he Company's troubled debt restructurings noted above do not include loans that are short-term modifications related to COVID-19 .

Fair Value

Fair Value	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value	6. FAIR VALUE The Company uses fair value measurements to record fair value adjustments to certain assets and to determine fair value disclosures. Fair values represent the estimated price that would be received from selling an asset or paid to transfer a liability, otherwise known as an “exit price.” Securities available for sale are recorded at fair value on a recurring basis. Additionally, from time to time, the Company may be required to record at fair value other assets on a nonrecurring basis. These nonrecurring fair value adjustments typically involve application of lower-of-cost-or-market accounting or write downs of individual assets. ASC Topic 820, “Fair Value Measurements and Disclosures” Fair Value Hierarchy The Company groups financial assets and financial liabilities measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Other significant observable inputs (including quoted prices in active markets for similar assets or liabilities) 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—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The fair value of an asset or liability is the price that would be received to sell that asset or paid to transfer that liability in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. In estimating fair value, the Company utilizes valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. Such valuation techniques are consistently applied. Inputs to valuation techniques include the assumptions that market participants would use in pricing an asset or liability. The fair value disclosures below represent the Company’s estimates based on relevant market information and information about the financial instruments. Fair value estimates are based on judgments regarding current economic conditions, risk characteristics of the various 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 the above methodologies and assumptions could significantly affect the estimates. The following tables present fair values for assets and liabilities measured at fair value on a recurring basis: As of June 30, 2020 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: Available for sale securities: States and political subdivisions $ — $ 306 $ — $ 306 Collateralized mortgage obligations — 263,715 — 263,715 Mortgage-backed securities — 46,024 — 46,024 Total $ — $ 310,045 $ — $ 310,045 Derivative financial instruments: Loan customer counterparty $ — $ 14,374 $ — $ 14,374 Financial institution counterparty — — — — Liabilities: Derivative financial instruments: Loan customer counterparty $ — $ — $ — $ — Financial institution counterparty — 14,374 — 14,374 As of December 31, 2019 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: Available for sale securities: States and political subdivisions $ — $ 471 $ — $ 471 Collateralized mortgage obligations — 235,773 — 235,773 Mortgage-backed securities — 51,419 — 51,419 Total available for sale securities $ — $ 287,663 $ — $ 287,663 Derivative financial instruments: Interest rate lock commitments $ — 305 $ — 305 Forward mortgage-backed securities trades — 3 — 3 Loan customer counterparty — 4,829 — 4,829 Financial institution counterparty — 240 — 240 Liabilities: Derivative financial instruments: Interest rate lock commitments $ — $ — $ — $ — Forward mortgage-backed securities trades — 83 — 83 Loan customer counterparty — 240 — 240 Financial institution counterparty — 4,829 — 4,829 Certain assets and liabilities are measured at fair value on a nonrecurring basis; that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (for example, when there is evidence of impairment). These instruments include other real estate owned, repossessed assets, held to maturity debt securities, loans held for sale and impaired loans, which are included as loans held for investment. For the three and six months ended June 30, 2020, the Company had additions to other real estate owned of $732 thousand and $844 thousand, respectively, of which $732 thousand and $800 thousand, respectively, were outstanding as of June 30, 2020. For the three and six months ended June 30, 2020, the Company had additions to impaired loans of $5.9 million and $17.4 million, respectively, of which $5.9 million and $17.4 million, respectively, were outstanding as of June 30, 2020. The remaining financial assets and liabilities measured at fair value on a non-recurring basis that were recorded in 2020 and remained outstanding at June 30, 2020 were not significant. The following tables present carrying and fair value information of financial instruments as of the dates indicated: As of June 30, 2020 Carrying Estimated Fair Value Amount Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets Cash and due from banks $ 332,873 $ 332,873 $ — $ — $ 332,873 Federal funds sold 568 568 — — 568 Held to maturity securities 7,407,541 — 7,600,435 — 7,600,435 Loans held for sale 39,516 — 39,516 — 39,516 Loans held for investment, net of allowance 18,104,269 — — 18,046,191 18,046,191 Loans held for investment - Warehouse Purchase Program 2,557,183 — 2,557,183 — 2,557,183 Other real estate owned 6,160 — 6,160 — 6,160 Liabilities Deposits: Noninterest-bearing $ 9,040,257 $ — $ 9,040,257 $ — $ 9,040,257 Interest-bearing 17,112,431 — 17,141,559 — 17,141,559 Other borrowings 103,131 — 103,373 — 103,373 Securities sold under repurchase agreements 365,335 — 365,368 — 365,368 Subordinated notes 125,365 — 126,175 — 126,175 As of December 31, 2019 Carrying Estimated Fair Value Amount Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets Cash and due from banks $ 573,589 $ 573,589 $ — $ — $ 573,589 Federal funds sold 519 519 — — 519 Held to maturity securities 8,282,393 — 8,303,851 — 8,303,851 Loans held for sale 80,959 — 80,959 — 80,959 Loans held for investment, net of allowance 17,124,156 — — 17,045,523 17,045,523 Loans held for investment - Warehouse Purchase Program 1,552,762 — 1,552,762 — 1,552,762 Other real estate owned 6,936 — 6,936 — 6,936 Liabilities Deposits: Noninterest-bearing $ 7,763,894 $ — $ 7,763,894 $ — $ 7,763,894 Interest-bearing 16,435,838 — 16,437,453 — 16,437,453 Other borrowings 1,303,730 — 1,303,941 — 1,303,941 Securities sold under repurchase agreements 377,294 — 377,302 — 377,302 Subordinated notes 125,804 — 125,743 — 125,743 The following is a description of the fair value estimates, methods and assumptions that are used by the Company in estimating the fair values of financial instruments. Loans held for sale — Loans held for sale are carried at the lower of cost or estimated fair value. Fair value for consumer mortgages held for sale is based on commitments on hand from investors or prevailing market prices. As such, the Company classifies loans held for sale subjected to nonrecurring fair value adjustments as Level 2. Loans held for investment — The Company does not record loans at fair value on a recurring basis. As such, valuation techniques discussed herein for loans are primarily for estimating fair value disclosures. The Company refined the calculation to estimate fair value for loans held for investment to be in accordance with ASU 2016-01. The refined discounted cash flow calculation to determine fair value considers internal and market-based information such as prepayment risk, cost of funds and liquidity. From time to time, the Company records nonrecurring fair value adjustments to impaired loans to reflect (1) partial write downs that are based on the observable market price or current appraised value of the collateral, or (2) the full charge-off of the loan carrying value. Where appraisals are not available, estimated cash flows are discounted using a rate commensurate with the credit risk associated with those cash flows. Assumptions regarding credit risk, cash flows and discount rates are judgmentally determined using available market information and specific borrower information. The Company classifies the estimated fair value of loans held for investment as Level 3. Other real estate owned — Other real estate owned is primarily foreclosed properties securing residential loans and commercial real estate. Foreclosed assets are adjusted to fair value less estimated costs to sell upon transfer of the loans to other real estate owned. Subsequently, these assets are carried at the lower of carrying value or fair value less estimated costs to sell. Other real estate carried at fair value based on an observable market price or a current appraised value is classified by the Company as Level 2. When management determines that the fair value of other real estate requires additional adjustments, either as a result of a non-current appraisal or when there is no observable market price, the Company classifies the other real estate as Level 3. The fair value estimates presented herein are based on pertinent information available to management at June 30, 2020. Although management is not aware of any factors that would significantly affect the estimated fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since those dates and, therefore, current estimates of fair value may differ significantly from the amounts presented herein.

Goodwill and Core Deposit Intan

Goodwill and Core Deposit Intangibles	6 Months Ended
	Jun. 30, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Core Deposit Intangibles	7. GOODWILL AND CORE DEPOSIT INTANGIBLES Changes in the carrying amount of the Company’s goodwill and core deposit intangibles for the six months ended June 30, 2020 and the year ended December 31, 2019 were as follows: Goodwill Core Deposit Intangibles (Dollars in thousands) Balance as of December 31, 2018 $ 1,900,845 $ 32,883 Less: Amortization — (6,537 ) Add: LegacyTexas Merger 1,322,826 60,058 Balance as of December 31, 2019 3,223,671 86,404 Less: Amortization — (6,656 ) Add: Measurement period adjustment of LegacyTexas Merger 8,293 — Balance as of June 30, 2020 $ 3,231,964 $ 79,748 Goodwill is recorded as of the acquisition date of each entity. The Company may record subsequent adjustments to goodwill for amounts undeterminable at acquisition date, such as deferred taxes and real estate valuations, and therefore the goodwill amounts may change accordingly. The Company initially records the total premium paid on acquisitions as goodwill. After finalizing the valuation, core deposit intangibles are identified and reclassified from goodwill to core deposit intangibles on the balance sheet. This reclassification has no effect on total assets, liabilities, shareholders’ equity, net income or cash flows. Management performs an evaluation annually, and more frequently if a triggering event occurs, of whether any impairment of the goodwill and core deposit intangibles has occurred. If any such impairment is determined, a write-down is recorded. As of June 30, 2020, there was no impairment recorded on goodwill and core deposit intangibles. The measurement period for the Company to determine the fair value of acquired identifiable assets and assumed liabilities will be at the end of the earlier of (1) twelve months from the date of acquisition or (2) as soon as the Company receives the information it was seeking about facts and circumstances that existed as of the date of acquisition. Core deposit intangibles are being amortized on a non-pro rata basis over their estimated lives, which the Company believes is between 10 and 15 years. Amortization expense related to intangible assets totaled $3.3 million and $1.3 million for the three months ended June 30, 2020 and 2019, respectively, and $6.7 million and $2.6 million for the six months ended June 30, 2020 and 2019, respectively. The estimated aggregate future amortization expense for core deposit intangibles remaining as of June 30, 2020 is as follows (dollars in thousands): Remaining 2020 $ 6,513 2021 11,551 2022 10,336 2023 9,360 2024 8,699 Thereafter 33,289 Total $ 79,748

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	8. INCOME TAXES Income tax expense totaled $9.4 million for the three months ended June 30, 2020 compared with $20.9 million for the same period in 2019, a decrease of $11.6 million or 55.2%. The decrease was primarily due to a tax benefit for net operating losses (“NOLs”) carryback of $20.1 million as a result of the CARES Act. Income tax expense totaled $44.2 million for the six months ended June 30, 2020 compared with $42.3 million for the same period in 2019, an increase of $1.9 million or 4.5%. The Company’s effective tax rate for the three months ended June 30, 2020 and 2019 was 6.7% and 20.6%, respectively. The Company’s effective tax rate for the six months ended June 30, 2020 and 2019 was 14.4% and 20.4%, respectively. The amount of federal and state income tax expense is influenced by the amount of pre-tax income, the amount of tax-exempt income and the amount of other nondeductible expenses. In response to the COVID-19 pandemic, on March 27, 2020, the President of the United States signed the CARES Act into law. The CARES Act permits a five-year carryback period for NOLs, which allowed the Company to generate an anticipated tax refund and income tax benefit resulting from the tax rate differential between the current statutory tax rate of 21 % and the 35 % statutory tax rate in prior years during the carryback period. Pursuant to this provision of the CARES Act, the Company recorded a federal current benefit for taxes on income for the six months ended June 30, 2020 due to the NOLs generated in 2019 that were used to offset taxable income generated between 201 4 and 2017 taxed at 35 % resulting in a tax benefit of $ 20.1 million, which is included in provision for income taxes in the accompanying condensed consolidated statements of income. This caused a reduction in the effective tax rate during the three and six months ended June 30, 2020 as NOLs carried back to tax years 201 4 through 2017 are applied at a federal tax rate of 35 % applicable to those tax years, compared to a 21 % tax rate effective at June 30, 2020. As a result, during the six months ended June 30, 2020, the Company’s total deferred tax asset decreased by $ 30.2 million.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	9. STOCK–BASED COMPENSATION At June 30, 2020, the Company had two stock-based employee compensation plans with awards outstanding. On March 3, 2020, Bancshares’ Board of Directors established the Prosperity Bancshares, Inc. 2020 Stock Incentive Plan (the “2020 Plan”), subject to approval by the Company’s shareholders. The Company’s shareholders approved the 2020 Plan at the annual meeting of shareholders on April 21, 2020. The 2020 Plan authorizes the issuance of up to 2,500,000 shares of common stock upon the exercise of options or pursuant to the grant or exercise, as the case may be, of other awards granted under the 2020 Plan, including incentive stock options, nonqualified stock options, stock appreciation rights, shares of restricted stock and restricted stock units. As of June 30, 2020, 12,500 shares of unvested restricted stock have been granted under the 2020 Plan. During 2012, Bancshares’ Board of Directors established the Prosperity Bancshares, Inc. 2012 Stock Incentive Plan (the “2012 Plan”), which was approved by Bancshares’ shareholders and authorized the issuance of up to 1,250,000 shares of common stock upon the exercise of options granted under the 2012 Plan or pursuant to the grant or exercise, as the case may be, of other awards granted under the 2012 Plan, including restricted stock, stock appreciation rights, phantom stock awards and performance awards. As of June 30, 2020, a total of 357,313 shares of common stock had been issued pursuant to vested awards; and 502,312 shares of unvested restricted stock had been granted under the 2012 Plan. The Company does not plan to make any further awards pursuant to the 2012 Plan. As of June 30, 2020, the Company had no stock options outstanding. Stock-based compensation expense related to restricted stock was $3.0 million and $2.3 million during the three months ended June 30, 2020 and 2019, respectively, and $6.3 million and $5.1 million during the six months ended June 30, 2020 and 2019. As of June 30, 2020, there was $12.0 million of total unrecognized compensation expense related to stock-based compensation arrangements. That cost is expected to be recognized over a weighted average period of 1.7 years.

Contractual Obligations and Off

Contractual Obligations and Off-Balance Sheet Items	6 Months Ended
	Jun. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Contractual Obligations and Off-Balance Sheet Items	10. CONTRACTUAL OBLIGATIONS AND OFF-BALANCE SHEET ITEMS Contractual Obligations The Company’s contractual obligations and other commitments to make future payments as of June 30, 2020 (other than deposit obligations and securities sold under repurchase agreements) are summarized below. The Company’s future cash payments associated with its contractual obligations pursuant to its subordinated notes and Federal Home Loan Bank (“FHLB”) advances and notes payable as of June 30, 2020 are summarized below. The future interest payments were calculated using the current rate in effect at June 30, 2020. Payments for the subordinated notes include interest of $29.1 million that will be due over the future periods. Payments for FHLB notes payable include interest of $245 thousand that will be paid over the future periods. The payments do not include pre-payment options that may be available to the Company. 1 year or less More than 1 year but less than 3 years 3 years or more but less than 5 years 5 years or more Total (Dollars in thousands) Subordinated notes $ 5,920 $ 10,475 $ 10,475 $ 127,548 $ 154,418 Federal Home Loan Bank advances and notes payable 101,597 1,316 442 21 103,376 Total $ 107,517 $ 11,791 $ 10,917 $ 127,569 $ 257,794 Leases The Company’s leases relate primarily to operating leases for office space and banking centers. The Company determines if an arrangement is a lease or contains a lease at inception. The Company’s leases have remaining lease terms of 1 to 18 years, which may include the option to extend the lease when it is reasonably certain for the Company to exercise that option. Operating lease right-of-use (ROU) assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. The Company uses its incremental collateralized borrowing rate to determine the present value of lease payments. Short-term leases and leases with variable lease costs are immaterial and the Company does not have any sublease arrangements. As of June 30, 2020, operating lease ROU assets and lease liabilities were approximately $52 million. ROU assets and lease liabilities were classified as other assets and other liabilities, respectively. As of June 30, 2020, the weighted average remaining lease terms of the Company’s operating leases were 7.6 years. The weighted average discount rate used to determine the lease liabilities as of June 30, 2020 for the Company’s operating leases was 2.43%. Cash paid for the Company’s operating leases for the three months ended June 30, 2020 and June 30, 2019 was $3.6 million and $1.4 million, respectively. Cash paid for the Company’s operating leases for the six months ended June 30, 2020 and June 30, 2019 was $7.2 million and $2.8 million, respectively. The Company obtained $1.5 million in ROU assets in exchange for lease liabilities for three operating leases during the six months ended June 30, 2020. The Company’s future undiscounted cash payments associated with its operating leases as of June 30, 2020 are summarized below (dollars in thousands). Remaining 2020 $ 4,604 2021 9,523 2022 8,998 2023 8,250 2024 7,369 2025 6,978 Thereafter 18,247 Total undiscounted lease payments $ 63,969 The following table presents a summary of non-cancelable future operating lease commitments as of December 31, 2019 (dollars in thousands): 2020 $ 10,137 2021 9,169 2022 8,641 2023 7,998 2024 7,119 Thereafter 24,996 Total non-cancelable lease payments $ 68,060 Off-Balance Sheet Items In the normal course of business, the Company enters into various transactions that, in accordance with GAAP, are not included in its consolidated balance sheets. The Company enters into these transactions to meet the financing needs of its customers. These transactions include commitments to extend credit and standby letters of credit, which involve, to varying degrees, elements of credit risk and interest rate risk in excess of the amounts recognized in the consolidated balance sheets. The Company’s commitments associated with outstanding standby letters of credit, unused capacity on Warehouse Purchase Program loans and commitments to extend credit expiring by period as of June 30, 2020 are summarized below. Since commitments associated with letters of credit, unused capacity of Warehouse Purchase Program loans, allowance for credit losses on off-balance sheet credit exposure and commitments to extend credit may expire unused, the amounts shown do not necessarily reflect the actual future cash funding requirements. 1 year or less More than 1 year but less than 3 years 3 years or more but less than 5 years 5 years or more Total (Dollars in thousands) Standby letters of credit $ 107,599 $ 9,196 $ 1,194 $ — $ 117,989 Unused capacity on Warehouse Purchase Program loans 690,817 — — — 690,817 Commitments to extend credit 1,798,300 1,711,257 591,779 1,265,829 5,367,165 Total $ 2,596,716 $ 1,720,453 $ 592,973 $ 1,265,829 $ 6,175,971 The Company funds an allowance for credit losses on off-balance sheet lending-related commitments and guarantees on credit card debt through a charge to provision for credit losses on the Company’s consolidated statement of income. At June 30, 2020 and December 31, 2019, this allowance for credit losses on off-balance sheet lending-related commitments and guarantees on credit card debt, included in “Allowance for credit losses on off-balance sheet credit exposure” on the Company’s consolidated balance sheet, totaled $29.9 million and $5.6 million, respectively.

Other Comprehensive Income

Other Comprehensive Income	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Other Comprehensive Income	11. OTHER COMPREHENSIVE INCOME The tax effects allocated to each component of other comprehensive income were as follows: Three Months Ended June 30, 2020 2019 Before Tax Amount Tax Effect Net of Tax Amount Before Tax Amount Tax Effect Net of Tax Amount (Dollars in thousands) Other comprehensive income: Securities available for sale: Change in unrealized gain during period $ 1,654 $ (347 ) $ 1,307 $ 716 $ (150 ) $ 566 Total securities available for sale 1,654 (347 ) 1,307 716 (150 ) 566 Total other comprehensive income $ 1,654 $ (347 ) $ 1,307 $ 716 $ (150 ) $ 566 Six Months Ended June 30, 2020 2019 Before Tax Amount Tax Effect Net of Tax Amount Before Tax Amount Tax Effect Net of Tax Amount (Dollars in thousands) Other comprehensive (loss) income: Securities available for sale: Change in unrealized gain during period $ (2,529 ) $ 531 $ (1,998 ) $ 1,219 $ (256 ) $ 963 Total securities available for sale (2,529 ) 531 (1,998 ) 1,219 (256 ) 963 Total other comprehensive (loss) income $ (2,529 ) $ 531 $ (1,998 ) $ 1,219 $ (256 ) $ 963 Activity in accumulated other comprehensive income associated with securities available for sale, net of tax, was as follows: Securities Available for Sale Accumulated Other Comprehensive Income (Dollars in thousands) Balance at December 31, 2019 $ 602 $ 602 Other comprehensive loss (1,998 ) (1,998 ) Balance at June 30, 2020 $ (1,396 ) $ (1,396 ) Balance at December 31, 2018 $ 310 $ 310 Other comprehensive income 963 963 Balance at June 30, 2019 $ 1,273 $ 1,273

Derivative Financial Instrument

Derivative Financial Instruments	6 Months Ended
	Jun. 30, 2020
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	12. DERIVATIVE FINANCIAL INSTRUMENTS The following table provides the outstanding notional balances and fair values of outstanding derivative positions at June 30, 2020 and December 31, 2019. June 30, 2020 December 31, 2019 Outstanding Notional Balance Asset Derivative Fair Value Liability Derivative Fair Value Outstanding Notional Balance Asset Derivative Fair Value Liability Derivative Fair Value (Dollars in thousands) Interest rate lock commitments $ — $ — $ — $ 9,438 $ 305 $ — Forward mortgage-backed securities trades — — — 40,750 3 83 Commercial loan interest rate swaps and caps: Loan customer counterparty 230,152 14,374 — 231,345 4,829 240 Financial institution counterparty 230,152 — 14,374 231,345 240 4,829 These financial instruments are not designated as hedging instruments and are used for asset and liability management and commercial customers’ financing needs. All derivatives are carried at fair value in either other assets or other liabilities. Interest rate lock commitments (“IRLCs”) - In the normal course of business, the Company enters into interest rate lock commitments with consumers to originate mortgage loans at a specified interest rate. These commitments, which contain fixed expiration dates, offer the borrower an interest rate guarantee provided the loan meets underwriting guidelines and closes within the timeframe established by the Company. Forward mortgage-backed securities trades - The Company manages the changes in fair value associated with changes in interest rates related to IRLCs by using forward sold commitments known as forward mortgage-backed securities trades. These instruments are typically entered into at the time the interest rate lock commitment is made. Interest rate swaps and caps - These derivative positions relate to transactions in which the Company enters into an interest rate swap or cap with a customer, while at the same time entering into an offsetting interest rate swap or cap with another financial institution. An interest rate swap transaction allows the Company’s customer to effectively convert a variable rate loan to a fixed rate. In connection with each swap, the Company agrees to pay interest to the customer on a notional amount at a variable interest rate and receive interest from the customer on a similar notional amount at a fixed interest rate. At the same time, the Company agrees to pay another financial institution the same fixed interest rate on the same notional amount and receive the same variable interest rate on the same notional amount. In connection with each interest rate cap, the Company sells a cap to the customer and agrees to pay interest if the underlying index exceeds the strike price defined in the cap agreement. Simultaneously the Company purchases a cap with matching terms from another financial institution that agrees to pay the Company if the underlying index exceeds the strike price. The commercial loan customer counterparty weighted average received and paid interest rates for interest rate swaps outstanding at June 30, 2020 and December 31, 2019 are presented in the following table. Weighted-Average Interest Rate June 30, 2020 December 31, 2019 Received Paid Received Paid Loan customer counterparty 0.84 % 2.86 % 3.42 % 2.86 % The Company’s credit exposure on interest rate swaps is limited to the net favorable value of all swaps by each counterparty, which was approximately $14.4 million at June 30, 2020 and $4.8 million at December 31, 2019. This credit exposure is partly mitigated as transactions with customers are secured by the collateral, if any, securing the underlying transaction being hedged. The Company’s credit exposure, net of collateral pledged, relating to interest rate swaps with upstream financial institution counter-parties was zero at June 30, 2020. A credit support annex is in place and allows the Company to call collateral from upstream financial institution counter-parties. Collateral levels are monitored and adjusted on a regular basis for changes in interest rate swap values. The Company’s cash collateral pledged for interest rate swaps was $14.3 million at June 30, 2020 and $9.3 The initial and subsequent changes in the fair value of IRLCs and the forward sales of mortgage-backed securities are recorded in net gain on sale of mortgage loans. These gains and losses were not attributable to instrument-specific credit risk. For interest rate swaps and caps, because the Company acts as an intermediary for its customer, changes in the fair value of the underlying derivative contracts substantially offset each other and do not have a material impact on its results of operations. Income (loss) for the three months ended June 30, 2020 and 2019 was as follows: Three Months Ended June 30, Six Months Ended June30, Derivatives not designated as hedging instruments 2020 2019 2020 2019 (Dollars in thousands) Interest rate lock commitments $ (1,417 ) $ — $ (305 ) $ — Forward mortgage-backed securities trades (461 ) — (2,398 ) —

Acquisitions

Acquisitions	6 Months Ended
	Jun. 30, 2020
Business Combinations [Abstract]
Acquisitions	13. ACQUISITIONS Acquisitions are an integral part of the Company’s growth strategy. All acquisitions were accounted for using the acquisition method of accounting. Accordingly, the assets and liabilities of the acquired entities were recorded at their fair values at the acquisition date. The excess of the purchase price over the estimated fair value of the net assets for tax-free acquisitions was recorded as goodwill, none of which is deductible for tax purposes. The excess of the purchase price over the estimated fair value of the net assets for taxable acquisitions was also recorded as goodwill, and is deductible for tax purposes. The identified core deposit intangibles for each acquisition are being amortized using a non-pro rata basis over an estimated life of 10 to 15 years. The results of operations for each acquisition have been included in the Company’s consolidated financial results beginning on the respective acquisition date. The measurement period for the Company to determine the fair values of acquired identifiable assets and assumed liabilities will end at the earlier of (1) twelve months from the date of the acquisition or (2) as soon as the Company receives the information it was seeking about facts and circumstances that existed as of the acquisition date or learns that more information is not obtainable. The following acquisitions were completed on the dates indicated: 2019 Acquisition Merger with LegacyTexas Financial Group, Inc. On November 1, 2019, LegacyTexas Financial Group, Inc. merged into Prosperity Bancshares and LegacyTexas Bank merged into the Bank. LegacyTexas was headquartered in Plano, Texas and operated 42 locations in 19 North Texas cities in and around the Dallas-Fort Worth area. As of September 30, 2019, LegacyTexas, on a consolidated basis, reported total assets of $10.5 billion, total gross loans of $9.1 billion, total deposits of $6.5 billion and shareholders’ equity of $1.2 billion. Pursuant to the terms of the merger agreement, Bancshares issued 26,228,148 shares of Bancshares common stock, with a closing price of $69.02 per share on November 1, 2019, plus $318.0 million in cash, comprised of $308.6 million in cash and $9.4 million in cash for taxes withheld, for all outstanding shares of LegacyTexas. The assets and liabilities of LegacyTexas were recorded on the consolidated balance sheet at estimated fair value on the acquisition date. As of June 30, 2020, the following table presents the amounts recorded on the consolidated balance sheet on the acquisition date (dollars in thousands). Initially Recorded at Acquisition Date Measurement Period Adjustments Adjusted Values as of June 30, 2020 Fair value of consideration paid: Common stock issued (26,228,148 shares) $ 1,810,267 $ — $ 1,810,267 Cash 318,018 — 318,018 Total consideration paid $ 2,128,285 $ — $ 2,128,285 Fair value of assets acquired: Cash and due from banks $ 228,649 $ — $ 228,649 Securities held to maturity 472,933 — 472,933 Loans held for sale 60,818 — 60,818 Loans held for investment 6,771,080 — 6,771,080 Loans held for investment - Warehouse Purchase Program 1,693,049 — 1,693,049 Bank premises and equipment 67,347 (1,833 ) 65,514 Other real estate owned 4,876 — 4,876 Core deposit intangibles 60,058 — 60,058 Federal Home Loan Bank stock 117,939 (113 ) 117,826 Bank owned life insurance and other assets 242,592 (7,013 ) 235,579 Total assets acquired 9,719,341 (8,959 ) 9,710,382 Fair value of liabilities assumed: Deposits 6,434,732 — 6,434,732 Other borrowings 2,078,682 — 2,078,682 Securities sold under repurchase agreements 57,670 — 57,670 Trust preferred securities 15,376 — 15,376 Subordinated notes 125,950 — 125,950 Other liabilities 201,472 (666 ) 200,806 Total liabilities assumed 8,913,882 (666 ) 8,913,216 Fair value of net assets acquired $ 805,459 $ (8,293 ) $ 797,166 Goodwill resulting from acquisition $ 1,322,826 $ 8,293 $ 1,331,119 The measurement period adjustments noted in the table above was a result of information obtained subsequent to the Company’s initial reporting of provisional fair values but prior to finalizing the fair values in accordance with ASC 805, Business Combinations. Such information was determined to be a condition in existence as of acquisition date. As of June 30, 2020, the Company recognized goodwill of $1.33 billion , which is subject to subsequent fair value adjustments Merger Related Expenses: The Company incurred $7.5 million and $8.0 million of pre-tax merger related expenses during the three and six months ended June 30, 2020, respectively. The Company incurred $46.4 million of pre-tax merger related expenses during the year ended December 31, 2019. The merger related expenses are reflected on the Company’s income statement for the applicable periods under “Merger related expenses” and consist of salaries and benefits, data processing and professional and legal fees. Pro Forma Information : Operations of LegacyTexas have been included in the consolidated financial statements since November 1, 2019. The following pro forma information presents the results of operations for the three and six months ended June 30, 2019, as if the Merger had occurred on January 1, 2019 (dollars in thousands, except per share amounts). Three Months Ended June 30, 2019 Six Months Ended June 30, 2019 Net interest income $ 270,971 $ 536,218 Net income 131,508 227,277 Basic earnings per share 1.37 2.37 Diluted earnings per share 1.37 2.37 The above pro forma results are presented for illustrative purposes and are not intended to represent or be indicative of the actual results of operations of the merged companies that would have been achieved had the Merger occurred on January 1, 2019, nor are they intended to represent or be indicative of future results of operations. The pro forma results do not include expected operating cost savings as a result of the acquisition. These pro forma results require significant estimates and judgments particularly as they relate to valuation and accretion of income associated with acquired loans. Pro forma adjustments principally included: • Reversing interest income and interest expense as previously recorded by LegacyTexas and recording interest income and interest expense based on impact of estimated fair values of the acquired interest-earning assets and assumed interest-bearing liabilities; • Reversing core deposit intangible amortization as previously recorded by LegacyTexas and recording amortization expense as it relates to the core deposit intangible recognized from the acquisition; and • Reporting merger related expenses as if they were incurred on January 1, 2019.

New Accounting Standards (Polic

New Accounting Standards (Policies)	6 Months Ended
	Jun. 30, 2020
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
Accounting Standards Updates (''ASU'')	Accounting Standards Updates (“ASU”) ASU 2020-04, "Reference Rate Reform: Facilitation of the Effects of Reference Rate Reform on Financial Reporting - Accounting Standards Codification (“ASC”) Topic 848 ASU 2020-04 provides optional expedients and exceptions for applying GAAP to loan and lease agreements, derivative contracts, and other transactions affected by the anticipated transition away from LIBOR toward new interest rate benchmarks. The guidance allows for companies to: (i) account for certain contract modifications as a continuation of the existing contract without additional analysis; (ii) continue hedge accounting when certain critical terms of a hedging relationship change and assess effectiveness in ways that disregard certain potential sources of ineffectiveness; and (iii) make a one-time sale and/or transfer of certain debt securities from held-to-maturity to available-for-sale or trading. This ASU is available for adoption effective March 12, 2020 through December 31, 2022. An entity may elect to apply ASU 2020-04 for contract modifications as of January 1, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic within ASU 2020-04, the amendments must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The one-time election to sell and/or transfer debt securities classified as held-to-maturity may be made at any time after March 12, 2020. The Company anticipates this ASU will simplify any modifications it executes between the selected start date (yet to be determined) and December 31, 2022 that are directly related to LIBOR transition by allowing prospective recognition of the continuation of the contract, rather than extinguishment of the old contract resulting in writing off unamortized fees and costs. ASU 2020-04 is not expected to have a significant impact on the Company’s financial statements. ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments (“ASC 326”).” On January 1, 2020 the Company adopted ASU 2016-13 which replaces the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (“CECL”) methodology. CECL requires a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The measurement of CECL is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The Company adopted ASU 2016-13 using the modified-retrospective method for all financial assets measured at amortized cost and off-balance sheet credit exposures. Reporting periods beginning after January 1, 2020 are presented under ASC 326 while prior periods are reported with previously applicable GAAP. Upon adoption of ASU 2016-13, the Company recognized an increase in allowance for credit losses for loans of $108.7 million, of which $102.5 million was related to LegacyTexas Financial Group, Inc. (“LegacyTexas”), which merged into Bancshares on November 1, 2019, and an increase in allowance for credit losses for off-balance sheet credit exposures of $24.4 million, of which $6.3 million was related to LegacyTexas, with a corresponding decrease in retained earnings (pre-tax). Additionally, the Company adopted ASU 2016-13 using the prospective transition approach for financial assets purchased with credit deterioration. The Company recognized an increase in the allowance for credit losses for loans of $131.8 million, of which $130.3 million was related to LegacyTexas, due to the reclass of purchased credit deteriorated discounts as the result of adopting ASU 2016-13. See Note 5 “Loans and Allowance for Credit Losses” for additional information. The Company recognized no allowance for credit losses related to debt securities. See Note 4 “Securities” for additional information. The following table illustrates the impact of adopting ASU 2016-13: January 1, 2020 As Reported Under ASC 326 Pre-ASC 326 Adoption Impact of ASC 326 Adoption (Dollars in thousands) Assets: Loans Construction, land development and other land loans $ 28,729 $ 14,654 $ 14,075 Agriculture and agriculture real estate (includes farmland) 5,768 2,971 2,797 1-4 family (includes home equity) 23,544 15,277 8,267 Commercial real estate (includes multi-family residential) 61,322 12,332 48,990 Commercial and industrial 180,069 40,445 139,624 Consumer and other 28,575 1,790 26,785 Allowance for credit losses on loans $ 328,007 $ 87,469 $ 240,538 Liabilities: Allowance for credit losses on off-balance sheet credit exposures $ 29,947 $ 5,599 $ 24,348

Income Per Common Share (Tables

Income Per Common Share (Tables)	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table illustrates the computation of basic and diluted earnings per share: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Amount Per Share Amount Amount Per Share Amount Amount Per Share Amount Amount Per Share Amount (Amounts in thousands, except per share data) Net income $ 130,901 $ 82,258 $ 261,749 $ 164,660 Basic: Weighted average shares outstanding 92,658 $ 1.41 69,806 $ 1.18 93,514 $ 2.80 69,832 $ 2.36 Diluted: Weighted average shares outstanding 92,658 $ 1.41 69,806 $ 1.18 93,514 $ 2.80 69,832 $ 2.36

New Accounting Standards (Table

New Accounting Standards (Tables)	6 Months Ended
	Jun. 30, 2020
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
Schedule of Impact of Adopting ASU 2016-13	The following table illustrates the impact of adopting ASU 2016-13: January 1, 2020 As Reported Under ASC 326 Pre-ASC 326 Adoption Impact of ASC 326 Adoption (Dollars in thousands) Assets: Loans Construction, land development and other land loans $ 28,729 $ 14,654 $ 14,075 Agriculture and agriculture real estate (includes farmland) 5,768 2,971 2,797 1-4 family (includes home equity) 23,544 15,277 8,267 Commercial real estate (includes multi-family residential) 61,322 12,332 48,990 Commercial and industrial 180,069 40,445 139,624 Consumer and other 28,575 1,790 26,785 Allowance for credit losses on loans $ 328,007 $ 87,469 $ 240,538 Liabilities: Allowance for credit losses on off-balance sheet credit exposures $ 29,947 $ 5,599 $ 24,348

Securities (Tables)

Securities (Tables)	6 Months Ended
	Jun. 30, 2020
Investments Debt And Equity Securities [Abstract]
Schedule of Amortized Cost and Fair Value of Investment Securities	The amortized cost and fair value of investment securities were as follows: June 30, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (Dollars in thousands) Available for Sale States and political subdivisions $ 305 $ 1 $ — $ 306 Collateralized mortgage obligations 265,422 163 (1,870 ) 263,715 Mortgage-backed securities 46,085 626 (687 ) 46,024 Total $ 311,812 $ 790 $ (2,557 ) $ 310,045 Held to Maturity U.S. Treasury securities and obligations of U.S. Government agencies $ 3,977 $ 50 $ — $ 4,027 States and political subdivisions 202,340 7,808 — 210,148 Collateralized mortgage obligations 154,390 2,725 (190 ) 156,925 Mortgage-backed securities 7,046,834 182,947 (446 ) 7,229,335 Total $ 7,407,541 $ 193,530 $ (636 ) $ 7,600,435 December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (Dollars in thousands) Available for Sale States and political subdivisions $ 470 $ 1 $ — $ 471 Collateralized mortgage obligations 235,222 690 (139 ) 235,773 Mortgage-backed securities 51,209 659 (449 ) 51,419 Total $ 286,901 $ 1,350 $ (588 ) $ 287,663 Held to Maturity U.S. Treasury securities and obligations of U.S. Government agencies $ 13,933 $ 58 $ — $ 13,991 States and political subdivisions 238,347 7,632 (189 ) 245,790 Collateralized mortgage obligations 203,470 1,115 (373 ) 204,212 Mortgage-backed securities 7,826,643 48,060 (34,845 ) 7,839,858 Total $ 8,282,393 $ 56,865 $ (35,407 ) $ 8,303,851
Securities in Continuous Loss Position	Securities with unrealized losses, segregated by length of time, that have been in a continuous loss position were as follows: June 30, 2020 Less than 12 Months 12 Months or More Total Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses (Dollars in thousands) Available for Sale Collateralized mortgage obligations $ 189,617 $ (1,859 ) $ 1,628 $ (11 ) $ 191,245 $ (1,870 ) Mortgage-backed securities 17,121 (400 ) 13,755 (287 ) 30,876 (687 ) Total $ 206,738 $ (2,259 ) $ 15,383 $ (298 ) $ 222,121 $ (2,557 ) Held to Maturity Collateralized mortgage obligations $ 40,895 $ (190 ) — — 40,895 (190 ) Mortgage-backed securities 37,652 (438 ) 1,443 (8 ) 39,095 (446 ) Total $ 78,547 $ (628 ) $ 1,443 $ (8 ) $ 79,990 $ (636 ) December 31, 2019 Less than 12 Months 12 Months or More Total Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses (Dollars in thousands) Available for Sale Collateralized mortgage obligations $ 50,245 $ (136 ) $ 1,818 $ (3 ) $ 52,063 $ (139 ) Mortgage-backed securities 34,901 (449 ) 10 — 34,911 (449 ) Total $ 85,146 $ (585 ) $ 1,828 $ (3 ) $ 86,974 $ (588 ) Held to Maturity States and political subdivisions $ 58,329 $ (183 ) $ 3,241 $ (6 ) $ 61,570 $ (189 ) Collateralized mortgage obligations 54,890 (373 ) — — 54,890 (373 ) Mortgage-backed securities 947,314 (3,017 ) 3,110,765 (31,828 ) 4,058,079 (34,845 ) Total $ 1,060,533 $ (3,573 ) $ 3,114,006 $ (31,834 ) $ 4,174,539 $ (35,407 )
Investment Securities by Contractual Maturity	The amortized cost and fair value of investment securities at June 30, 2020, by contractual maturity, are shown below. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations at any time with or without call or prepayment penalties. Held to Maturity Available for Sale Amortized Cost Fair Value Amortized Cost Fair Value (Dollars in thousands) Due in one year or less $ 29,087 $ 29,280 $ 305 $ 306 Due after one year through five years 114,383 119,288 — — Due after five years through ten years 56,229 58,779 — — Due after ten years 6,618 6,828 — — Subtotal 206,317 214,175 305 306 Mortgage-backed securities and collateralized mortgage obligations 7,201,224 7,386,260 311,507 309,739 Total $ 7,407,541 $ 7,600,435 $ 311,812 $ 310,045

Loans and Allowance for Credi_2

Loans and Allowance for Credit Losses (Tables)	6 Months Ended
	Jun. 30, 2020
Receivables [Abstract]
Types of Loans in Loan Portfolio	The loan portfolio consists of various types of loans and is categorized by major type as follows: June 30, 2020 December 31, 2019 (Dollars in thousands) Residential mortgage loans held for sale $ 39,516 $ 80,959 Commercial and industrial 4,227,102 3,205,595 Real estate: Construction, land development and other land loans 2,033,037 2,064,167 1-4 family residential (includes home equity) 4,582,554 4,306,452 Commercial real estate (includes multi-family residential) 6,550,086 6,556,285 Farmland 429,963 495,558 Agriculture 182,731 185,297 Consumer and other 423,001 398,271 Total loans held for investment, excluding Warehouse Purchase Program 18,428,474 17,211,625 Warehouse Purchase Program 2,557,183 1,552,762 Total loans, including Warehouse Purchase Program $ 21,025,173 $ 18,845,346
Related Party Loans	An analysis of activity with respect to these related party loans is as follows: As of and for the six months ended June 30, 2020 As of and for the year ended December (Dollars in thousands) Beginning balance on January 1 $ 4,152 $ 1,923 New loans 810 1 Transfers — 2,500 Repayments (109 ) (272 ) Ending balance $ 4,853 $ 4,152
Aging Analysis of Past Due Loans	An aging analysis of past due loans, segregated by category of loan, is presented below: June 30, 2020 Loans Past Due and Still Accruing 30-89 Days 90 or More Days Total Past Due Loans Nonaccrual Loans Current Loans Total Loans (Dollars in thousands) Construction, land development and other land loans $ 13,846 $ 8,287 $ 22,133 $ 2,243 $ 2,008,661 $ 2,033,037 Warehouse Purchase Program loans — — — — 2,557,183 2,557,183 Agriculture and agriculture real estate (includes farmland) 3,008 — 3,008 769 608,917 612,694 1-4 family (includes home equity) (1) 9,098 43 9,141 29,642 4,583,287 4,622,070 Commercial real estate (includes multi-family residential) 7,881 319 8,200 15,129 6,526,757 6,550,086 Commercial and industrial 12,085 25 12,110 15,057 4,199,935 4,227,102 Consumer and other 3,915 17 3,932 64 419,005 423,001 Total $ 49,833 $ 8,691 $ 58,524 $ 62,904 $ 20,903,745 $ 21,025,173 December 31, 2019 Loans Past Due and Still Accruing 30-89 Days 90 or More Days Total Past Due Loans Nonaccrual Loans Current Loans Total Loans (Dollars in thousands) Construction, land development and other land loans $ 16,470 $ — $ 16,470 $ 1,142 $ 2,046,555 $ 2,064,167 Warehouse Purchase Program loans — — — — 1,552,762 1,552,762 Agriculture and agriculture real estate (includes farmland) 466 — 466 103 680,286 680,855 1-4 family (includes home equity) (1) 43,884 441 44,325 24,413 4,318,673 4,387,411 Commercial real estate (includes multi-family residential) 10,669 — 10,669 12,714 6,532,902 6,556,285 Commercial and industrial 7,249 — 7,249 16,809 3,181,537 3,205,595 Consumer and other 1,708 — 1,708 62 396,501 398,271 Total $ 80,446 $ 441 $ 80,887 $ 55,243 $ 18,709,216 $ 18,845,346 (1) Includes $39.5 million and $81.0 million of residential mortgage loans held for sale at June 30, 2020 and December 31, 2019, respectively.
Non-performing Assets	The following table presents information regarding nonperforming assets as of the dates indicated: June 30, 2020 December 31, 2019 (Dollars in thousands) Nonaccrual loans (1) (2) $ 62,904 $ 55,243 Accruing loans 90 or more days past due 8,691 441 Total nonperforming loans 71,595 55,684 Repossessed assets 187 323 Other real estate 6,160 6,936 Total nonperforming assets $ 77,942 $ 62,943 Nonperforming assets to total loans and other real estate 0.37 % 0.33 % Nonperforming assets to total loans, excluding Warehouse Purchase Program loans, and other real estate 0.42 % 0.36 % (1) Includes troubled debt restructurings of $13.6 million as of both June 30, 2020 and December 31, 2019. (2) There were no nonperforming or troubled debt restructurings of warehouse lines of credit or Warehouse Purchase Program loans for the periods presented.
Recorded Investment and Outstanding Balance for Purchased Credit Deteriorated Loans and Non Purchased Credit Deteriorated Loans	The recorded investment in PCD loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below. The outstanding balance represents the total amount owed as of June 30, 2020 and December 31, 2019 . June 30, 2020 December 31, 2019 (Dollars in thousands) PCD loans: Outstanding balance $ 290,189 $ 410,785 Discount (1) (22,565 ) (167,320 ) (2) Recorded investment $ 267,624 $ 243,465 (1) ASU 2016-13 became effective for the Company on January 1, 2020. (2) Includes $131.8 million in PCD loans credit discount. June 30, 2020 December 31, 2019 (Dollars in thousands) Non-PCD loans: Outstanding balance $ 5,117,679 $ 6,102,540 Discount (69,860 ) (110,130 ) Recorded investment $ 5,047,819 $ 5,992,410
Summary of Changes in Accretable Yields of Acquired Loans	Changes in the accretable yield for acquired PCD loans for the three and six months ended June 30, 2020 and 2019 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (Dollars in thousands) Balance at beginning of period $ 29,460 $ 1,234 $ 35,654 $ 1,534 Adjustments (274 ) 17 (449 ) 36 Accretion charge-offs (354 ) — (354 ) — Accretion (6,267 ) (347 ) (12,286 ) (666 ) Balance at June 30, $ 22,565 $ 904 $ 22,565 $ 904 Changes in the discount accretion for Non-PCD loans for the three and six months ended June 30, 2020 and 2019 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (Dollars in thousands) Balance at beginning of period $ 87,613 $ 13,359 $ 110,130 $ 14,833 Adjustments 312 — 312 — Accretion charge-offs (66 ) — (120 ) — Accretion (17,999 ) (880 ) (40,462 ) (2,354 ) Balance at June 30, $ 69,860 $ 12,479 $ 69,860 $ 12,479
Risk Grade and Category of Loan	The following table presents loans by risk grade and category of loan at June 30, 2020. Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Loans Total (Dollars in thousands) Construction, Land Development and Other Land Loans Grade 1 $ — $ — $ — $ — $ — $ 27 $ — $ — $ 27 Grade 2 — — — 88 132 281 — — 501 Grade 3 345,184 702,893 417,348 116,076 38,311 74,496 120,229 1,637 1,816,174 Grade 4 6,435 16,742 33,221 113,509 7,056 13,771 9,682 — 200,416 Grade 5 — — — 4 — 2,910 — — 2,914 Grade 6 — — — — — 2,202 — — 2,202 Grade 7 — — 1,118 — — 390 734 — 2,242 Grade 8 — — — — — — — — — Grade 9 — — — — — — — — — PCD Loans — 1,305 — 397 — 6,859 — — 8,561 Total $ 351,619 $ 720,940 $ 451,687 $ 230,074 $ 45,499 $ 100,936 $ 130,645 $ 1,637 $ 2,033,037 Agriculture and Agriculture Real Estate (includes Farmland) Grade 1 $ 695 $ 380 $ 308 $ 255 $ 103 $ 526 $ 10,100 $ — $ 12,367 Grade 2 10 — — 355 — 1,591 40 — 1,996 Grade 3 68,790 90,926 71,576 49,393 57,106 110,608 75,452 1,252 525,103 Grade 4 8,750 9,697 4,798 3,083 5,099 22,535 5,912 — 59,874 Grade 5 1,654 3,419 1,130 — — 648 2,043 — 8,894 Grade 6 1,468 — 59 — 186 184 — — 1,897 Grade 7 — 353 32 — 4 357 — — 746 Grade 8 — — — — — — — — — Grade 9 — — — — — — — — — PCD Loans — 217 — — — 1,294 — 306 1,817 Total $ 81,367 $ 104,992 $ 77,903 $ 53,086 $ 62,498 $ 137,743 $ 93,547 $ 1,558 $ 612,694 1-4 Family (includes Home Equity) (1) Grade 1 $ 98 $ — $ — $ — $ — $ — $ — $ — $ 98 Grade 2 — 71 121 728 260 11,068 1,335 — 13,583 Grade 3 644,503 909,952 610,756 532,702 512,549 1,114,277 139,042 5,022 4,468,803 Grade 4 1,980 12,884 18,229 13,841 10,496 38,260 2,722 138 98,550 Grade 5 — 164 — 1,258 232 4,082 — — 5,736 Grade 6 85 42 3 328 — 2,165 — 32 2,655 Grade 7 — 1,746 986 2,887 3,159 13,590 3,587 — 25,955 Grade 8 — — — — — 99 — — 99 Grade 9 — — — — — — — — — PCD Loans — — — — 251 5,300 1,040 — 6,591 Total $ 646,666 $ 924,859 $ 630,095 $ 551,744 $ 526,947 $ 1,188,841 $ 147,726 $ 5,192 $ 4,622,070 Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Loans Total (Dollars in thousands) Commercial Real Estate (includes Multi-Family Residential) Grade 1 $ — $ — $ — $ — $ — $ — $ — $ — $ — Grade 2 5,743 2,008 — 7,480 193 4,980 — — 20,404 Grade 3 188,791 1,035,743 1,022,056 1,037,919 641,974 1,432,384 73,808 40,429 5,473,104 Grade 4 13,295 34,582 114,906 149,851 157,957 391,781 13,272 345 875,989 Grade 5 — — 2,164 12,888 12,575 14,521 — — 42,148 Grade 6 7,928 175 1,250 26 3,218 8,165 1,500 — 22,262 Grade 7 21 — — 16 14,796 210 — — 15,043 Grade 8 — — — — — — — — — Grade 9 — — — — — — — — — PCD Loans — 15,329 5,094 27,440 — 53,273 — — 101,136 Total $ 215,778 $ 1,087,837 $ 1,145,470 $ 1,235,620 $ 830,713 $ 1,905,314 $ 88,580 $ 40,774 $ 6,550,086 Commercial and Industrial Grade 1 $ 1,379,014 $ 8,123 $ 7,034 $ 3,487 $ 1,597 $ 7,345 $ 20,344 $ 23 $ 1,426,967 Grade 2 999 155 1,137 1,530 1,442 1,132 21,124 62,772 90,291 Grade 3 173,841 331,439 226,143 116,920 111,163 185,271 792,523 263,799 2,201,099 Grade 4 10,170 53,041 22,132 29,046 11,293 50,492 66,940 28,947 272,061 Grade 5 3,057 16,813 476 157 297 2,359 7,568 114 30,841 Grade 6 101 243 2,492 206 1,266 2,254 23,442 650 30,654 Grade 7 — 570 367 110 649 12,963 31,650 1,449 47,758 Grade 8 — — — — 10 — — — 10 Grade 9 — — — — — — — — — PCD Loans 790 28,991 8,280 11,746 3,582 1,715 49,350 22,967 127,421 Total $ 1,567,972 $ 439,375 $ 268,061 $ 163,202 $ 131,299 $ 263,531 $ 1,012,941 $ 380,721 $ 4,227,102 Consumer and Other Grade 1 $ 26,314 $ 10,550 $ 5,938 $ 4,882 $ 2,519 $ 6,334 $ 1,518 $ 3 $ 58,058 Grade 2 2,345 10,763 418 38,306 233 1,402 1,185 — 54,652 Grade 3 33,702 54,277 36,175 18,500 7,721 30,553 75,869 338 257,135 Grade 4 478 4,219 964 77 109 2,084 11,057 4 18,992 Grade 5 — — 68 18 — — 10,402 — 10,488 Grade 6 — 1,534 — — — — — — 1,534 Grade 7 — 32 8 6 (5 ) 3 — — 44 Grade 8 — — — — — — — — — Grade 9 — — — — — — — — — PCD Loans — — — 1,880 — 3,800 16,418 — 22,098 Total $ 62,839 $ 81,375 $ 43,571 $ 63,669 $ 10,577 $ 44,176 $ 116,449 $ 345 $ 423,001 Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Loans Total (Dollars in thousands) Warehouse Purchase Program Grade 1 $ — $ — $ — $ — $ — $ — $ — $ — $ — Grade 2 — — — — — — — — — Grade 3 2,557,183 — — — — — — — 2,557,183 Grade 4 — — — — — — — — — Grade 5 — — — — — — — — — Grade 6 — — — — — — — — — Grade 7 — — — — — — — — — Grade 8 — — — — — — — — — Grade 9 — — — — — — — — — PCD Loans — — — — — — — — — Total $ 2,557,183 $ — $ — $ — $ — $ — $ — $ — $ 2,557,183 Total Grade 1 $ 1,406,121 $ 19,053 $ 13,280 $ 8,624 $ 4,219 $ 14,232 $ 31,962 $ 26 $ 1,497,517 Grade 2 9,097 12,997 1,676 48,487 2,260 20,454 23,684 62,772 181,427 Grade 3 4,011,994 3,125,230 2,384,054 1,871,510 1,368,824 2,947,589 1,276,923 312,477 17,298,601 Grade 4 41,108 131,165 194,250 309,407 192,010 518,923 109,585 29,434 1,525,882 Grade 5 4,711 20,396 3,838 14,325 13,104 24,520 20,013 114 101,021 Grade 6 9,582 1,994 3,804 560 4,670 14,970 24,942 682 61,204 Grade 7 21 2,701 2,511 3,019 18,603 27,513 35,971 1,449 91,788 Grade 8 — — — — 10 99 — — 109 Grade 9 — — — — — — — — — PCD Loans 790 45,842 13,374 41,463 3,833 72,241 66,808 23,273 267,624 Total $ 5,483,424 $ 3,359,378 $ 2,616,787 $ 2,297,395 $ 1,607,533 $ 3,640,541 $ 1,589,888 $ 430,227 $ 21,025,173 (1) Includes $39.5 million of residential mortgage loans held for sale at June 30, 2020.
Allowance for Credit Losses on Loans by Category of Loan	The following table details activity in the allowance for credit losses on loans by category of loan for the three and six months ended June 30, 2020 and 2019. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. Construction, Land Development and Other Land Loans Agriculture and Agriculture Real Estate (includes Farmland) 1-4 Family (includes Home Equity) Commercial Real Estate (includes Multi-Family Residential) Commercial and Industrial Consumer and Other Total (Dollars in thousands) Allowance for credit losses: Three Months Ended Balance March 31, 2020 $ 28,741 $ 5,769 $ 23,539 $ 61,403 $ 180,097 $ 27,657 $ 327,206 Provision for credit losses 11,115 1,126 9,533 16,804 (18,007 ) (10,571 ) 10,000 Charge-offs — (32 ) (145 ) — (12,678 ) (1,121 ) (13,976 ) Recoveries 6 35 94 — 472 368 975 Net charge-offs 6 3 (51 ) — (12,206 ) (753 ) (13,001 ) Balance June 30, 2020 $ 39,862 $ 6,898 $ 33,021 $ 78,207 $ 149,884 $ 16,333 $ 324,205 Six Months Ended Beginning balance, prior to adoption of ASC 326 $ 14,654 $ 2,971 $ 15,277 $ 12,332 $ 40,445 $ 1,790 $ 87,469 Impact of adoption ASC 326 14,075 2,797 8,267 48,990 139,624 26,785 240,538 Provision for credit losses 11,115 1,126 9,533 16,804 (18,007 ) (10,571 ) 10,000 Charge-offs — (62 ) (175 ) — (13,289 ) (2,437 ) (15,963 ) Recoveries 18 66 119 81 1,111 766 2,161 Net charge-offs 18 4 (56 ) 81 (12,178 ) (1,671 ) (13,802 ) Balance June 30, 2020 $ 39,862 $ 6,898 $ 33,021 $ 78,207 $ 149,884 $ 16,333 $ 324,205 Allowance for credit losses: Three Months Ended Balance March 31, 2019 $ 16,192 $ 3,284 $ 14,455 $ 11,590 $ 39,059 $ 1,511 $ 86,091 Provision for credit losses (299 ) 578 (61 ) 575 (710 ) 717 800 Charge-offs (19 ) (54 ) (16 ) — (125 ) (905 ) (1,119 ) Recoveries 12 8 5 1 953 255 1,234 Net charge-offs (7 ) (46 ) (11 ) 1 828 (650 ) 115 Balance June 30, 2019 $ 15,886 $ 3,816 $ 14,383 $ 12,166 $ 39,177 $ 1,578 $ 87,006 Six Months Ended Balance December 31, 2018 $ 15,582 $ 3,693 $ 14,135 $ 11,220 $ 40,223 $ 1,587 $ 86,440 Provision for credit losses 311 (1,109 ) 256 944 (155 ) 1,253 1,500 Charge-offs (63 ) (64 ) (22 ) — (2,082 ) (1,797 ) (4,028 ) Recoveries 56 1,296 14 2 1,191 535 3,094 Net charge-offs (7 ) 1,232 (8 ) 2 (891 ) (1,262 ) (934 ) Balance June 30, 2019 $ 15,886 $ 3,816 $ 14,383 $ 12,166 $ 39,177 $ 1,578 $ 87,006
Troubled Debt Restructurings	The following table presents information regarding the recorded investment of loans that were modified as troubled debt restructurings during the six months ended June 30, 2020 and 2019. Six Months Ended June 30, 2020 2019 Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment (Dollars in thousands) Troubled Debt Restructurings Construction, land development and other land loans — $ — $ — — $ — $ — Agriculture and agriculture real estate (includes farmland) — — — — — — 1-4 Family (includes home equity) 1 23 13 — — — Commercial real estate (includes multi-family residential) — — — — — — Commercial and industrial — — — 1 14,783 14,258 Consumer and other — — — — — — Total 1 $ 23 $ 13 1 $ 14,783 $ 14,258

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Assets and Liabilities Measured on Recurring Basis	The following tables present fair values for assets and liabilities measured at fair value on a recurring basis: As of June 30, 2020 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: Available for sale securities: States and political subdivisions $ — $ 306 $ — $ 306 Collateralized mortgage obligations — 263,715 — 263,715 Mortgage-backed securities — 46,024 — 46,024 Total $ — $ 310,045 $ — $ 310,045 Derivative financial instruments: Loan customer counterparty $ — $ 14,374 $ — $ 14,374 Financial institution counterparty — — — — Liabilities: Derivative financial instruments: Loan customer counterparty $ — $ — $ — $ — Financial institution counterparty — 14,374 — 14,374 As of December 31, 2019 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: Available for sale securities: States and political subdivisions $ — $ 471 $ — $ 471 Collateralized mortgage obligations — 235,773 — 235,773 Mortgage-backed securities — 51,419 — 51,419 Total available for sale securities $ — $ 287,663 $ — $ 287,663 Derivative financial instruments: Interest rate lock commitments $ — 305 $ — 305 Forward mortgage-backed securities trades — 3 — 3 Loan customer counterparty — 4,829 — 4,829 Financial institution counterparty — 240 — 240 Liabilities: Derivative financial instruments: Interest rate lock commitments $ — $ — $ — $ — Forward mortgage-backed securities trades — 83 — 83 Loan customer counterparty — 240 — 240 Financial institution counterparty — 4,829 — 4,829
Summary of Carrying and Fair Value Information of Financial Instruments	The following tables present carrying and fair value information of financial instruments as of the dates indicated: As of June 30, 2020 Carrying Estimated Fair Value Amount Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets Cash and due from banks $ 332,873 $ 332,873 $ — $ — $ 332,873 Federal funds sold 568 568 — — 568 Held to maturity securities 7,407,541 — 7,600,435 — 7,600,435 Loans held for sale 39,516 — 39,516 — 39,516 Loans held for investment, net of allowance 18,104,269 — — 18,046,191 18,046,191 Loans held for investment - Warehouse Purchase Program 2,557,183 — 2,557,183 — 2,557,183 Other real estate owned 6,160 — 6,160 — 6,160 Liabilities Deposits: Noninterest-bearing $ 9,040,257 $ — $ 9,040,257 $ — $ 9,040,257 Interest-bearing 17,112,431 — 17,141,559 — 17,141,559 Other borrowings 103,131 — 103,373 — 103,373 Securities sold under repurchase agreements 365,335 — 365,368 — 365,368 Subordinated notes 125,365 — 126,175 — 126,175 As of December 31, 2019 Carrying Estimated Fair Value Amount Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets Cash and due from banks $ 573,589 $ 573,589 $ — $ — $ 573,589 Federal funds sold 519 519 — — 519 Held to maturity securities 8,282,393 — 8,303,851 — 8,303,851 Loans held for sale 80,959 — 80,959 — 80,959 Loans held for investment, net of allowance 17,124,156 — — 17,045,523 17,045,523 Loans held for investment - Warehouse Purchase Program 1,552,762 — 1,552,762 — 1,552,762 Other real estate owned 6,936 — 6,936 — 6,936 Liabilities Deposits: Noninterest-bearing $ 7,763,894 $ — $ 7,763,894 $ — $ 7,763,894 Interest-bearing 16,435,838 — 16,437,453 — 16,437,453 Other borrowings 1,303,730 — 1,303,941 — 1,303,941 Securities sold under repurchase agreements 377,294 — 377,302 — 377,302 Subordinated notes 125,804 — 125,743 — 125,743

Goodwill and Core Deposit Int_2

Goodwill and Core Deposit Intangibles (Tables)	6 Months Ended
	Jun. 30, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Core Deposit Intangibles	Changes in the carrying amount of the Company’s goodwill and core deposit intangibles for the six months ended June 30, 2020 and the year ended December 31, 2019 were as follows: Goodwill Core Deposit Intangibles (Dollars in thousands) Balance as of December 31, 2018 $ 1,900,845 $ 32,883 Less: Amortization — (6,537 ) Add: LegacyTexas Merger 1,322,826 60,058 Balance as of December 31, 2019 3,223,671 86,404 Less: Amortization — (6,656 ) Add: Measurement period adjustment of LegacyTexas Merger 8,293 — Balance as of June 30, 2020 $ 3,231,964 $ 79,748
Estimated Aggregate Future Amortization Expense for Core Deposit Intangibles	The estimated aggregate future amortization expense for core deposit intangibles remaining as of June 30, 2020 is as follows (dollars in thousands): Remaining 2020 $ 6,513 2021 11,551 2022 10,336 2023 9,360 2024 8,699 Thereafter 33,289 Total $ 79,748

Contractual Obligations and O_2

Contractual Obligations and Off-Balance Sheet Items (Tables)	6 Months Ended
	Jun. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Schedule of Contractual Obligations and Other Commitments	The Company’s contractual obligations and other commitments to make future payments as of June 30, 2020 (other than deposit obligations and securities sold under repurchase agreements) are summarized below. 1 year or less More than 1 year but less than 3 years 3 years or more but less than 5 years 5 years or more Total (Dollars in thousands) Subordinated notes $ 5,920 $ 10,475 $ 10,475 $ 127,548 $ 154,418 Federal Home Loan Bank advances and notes payable 101,597 1,316 442 21 103,376 Total $ 107,517 $ 11,791 $ 10,917 $ 127,569 $ 257,794
Future Undiscounted Cash Payments Associated with its Operating Leases	The Company’s future undiscounted cash payments associated with its operating leases as of June 30, 2020 are summarized below (dollars in thousands). Remaining 2020 $ 4,604 2021 9,523 2022 8,998 2023 8,250 2024 7,369 2025 6,978 Thereafter 18,247 Total undiscounted lease payments $ 63,969
Summary of Non-Cancelable Future Operating Lease Commitments	The following table presents a summary of non-cancelable future operating lease commitments as of December 31, 2019 (dollars in thousands): 2020 $ 10,137 2021 9,169 2022 8,641 2023 7,998 2024 7,119 Thereafter 24,996 Total non-cancelable lease payments $ 68,060
Summary of Commitments Associated with Outstanding Standby Letters of Credit, Unused Capacity on Warehouse Purchase Program Loans and Commitments to Extend Credit	The Company’s commitments associated with outstanding standby letters of credit, unused capacity on Warehouse Purchase Program loans and commitments to extend credit expiring by period as of June 30, 2020 are summarized below. Since commitments associated with letters of credit, unused capacity of Warehouse Purchase Program loans, allowance for credit losses on off-balance sheet credit exposure and commitments to extend credit may expire unused, the amounts shown do not necessarily reflect the actual future cash funding requirements. 1 year or less More than 1 year but less than 3 years 3 years or more but less than 5 years 5 years or more Total (Dollars in thousands) Standby letters of credit $ 107,599 $ 9,196 $ 1,194 $ — $ 117,989 Unused capacity on Warehouse Purchase Program loans 690,817 — — — 690,817 Commitments to extend credit 1,798,300 1,711,257 591,779 1,265,829 5,367,165 Total $ 2,596,716 $ 1,720,453 $ 592,973 $ 1,265,829 $ 6,175,971

Other Comprehensive Income (Tab

Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Tax Effects Allocated to Each Component of Other Comprehensive Income	The tax effects allocated to each component of other comprehensive income were as follows: Three Months Ended June 30, 2020 2019 Before Tax Amount Tax Effect Net of Tax Amount Before Tax Amount Tax Effect Net of Tax Amount (Dollars in thousands) Other comprehensive income: Securities available for sale: Change in unrealized gain during period $ 1,654 $ (347 ) $ 1,307 $ 716 $ (150 ) $ 566 Total securities available for sale 1,654 (347 ) 1,307 716 (150 ) 566 Total other comprehensive income $ 1,654 $ (347 ) $ 1,307 $ 716 $ (150 ) $ 566 Six Months Ended June 30, 2020 2019 Before Tax Amount Tax Effect Net of Tax Amount Before Tax Amount Tax Effect Net of Tax Amount (Dollars in thousands) Other comprehensive (loss) income: Securities available for sale: Change in unrealized gain during period $ (2,529 ) $ 531 $ (1,998 ) $ 1,219 $ (256 ) $ 963 Total securities available for sale (2,529 ) 531 (1,998 ) 1,219 (256 ) 963 Total other comprehensive (loss) income $ (2,529 ) $ 531 $ (1,998 ) $ 1,219 $ (256 ) $ 963
Activity in Accumulated Other Comprehensive Income Associated with Securities Available for Sale, Net of Tax	Activity in accumulated other comprehensive income associated with securities available for sale, net of tax, was as follows: Securities Available for Sale Accumulated Other Comprehensive Income (Dollars in thousands) Balance at December 31, 2019 $ 602 $ 602 Other comprehensive loss (1,998 ) (1,998 ) Balance at June 30, 2020 $ (1,396 ) $ (1,396 ) Balance at December 31, 2018 $ 310 $ 310 Other comprehensive income 963 963 Balance at June 30, 2019 $ 1,273 $ 1,273

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2020
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Schedule of Notional Balances and Fair Value of Derivative Positions	The following table provides the outstanding notional balances and fair values of outstanding derivative positions at June 30, 2020 and December 31, 2019. June 30, 2020 December 31, 2019 Outstanding Notional Balance Asset Derivative Fair Value Liability Derivative Fair Value Outstanding Notional Balance Asset Derivative Fair Value Liability Derivative Fair Value (Dollars in thousands) Interest rate lock commitments $ — $ — $ — $ 9,438 $ 305 $ — Forward mortgage-backed securities trades — — — 40,750 3 83 Commercial loan interest rate swaps and caps: Loan customer counterparty 230,152 14,374 — 231,345 4,829 240 Financial institution counterparty 230,152 — 14,374 231,345 240 4,829
Schedule of Weighted Average Received and Paid Interest Rates for Interest Rate Swaps Outstanding	The commercial loan customer counterparty weighted average received and paid interest rates for interest rate swaps outstanding at June 30, 2020 and December 31, 2019 are presented in the following table. Weighted-Average Interest Rate June 30, 2020 December 31, 2019 Received Paid Received Paid Loan customer counterparty 0.84 % 2.86 % 3.42 % 2.86 %
Schedule of Income (Loss) from Derivatives Not Designated as Hedging Instruments	Income (loss) for the three months ended June 30, 2020 and 2019 was as follows: Three Months Ended June 30, Six Months Ended June30, Derivatives not designated as hedging instruments 2020 2019 2020 2019 (Dollars in thousands) Interest rate lock commitments $ (1,417 ) $ — $ (305 ) $ — Forward mortgage-backed securities trades (461 ) — (2,398 ) —

Acquisitions (Tables)

Acquisitions (Tables)	6 Months Ended
	Jun. 30, 2020
Business Combinations [Abstract]
Amounts Recorded on Consolidated Balance Sheet on Acquisition Date	The assets and liabilities of LegacyTexas were recorded on the consolidated balance sheet at estimated fair value on the acquisition date. As of June 30, 2020, the following table presents the amounts recorded on the consolidated balance sheet on the acquisition date (dollars in thousands). Initially Recorded at Acquisition Date Measurement Period Adjustments Adjusted Values as of June 30, 2020 Fair value of consideration paid: Common stock issued (26,228,148 shares) $ 1,810,267 $ — $ 1,810,267 Cash 318,018 — 318,018 Total consideration paid $ 2,128,285 $ — $ 2,128,285 Fair value of assets acquired: Cash and due from banks $ 228,649 $ — $ 228,649 Securities held to maturity 472,933 — 472,933 Loans held for sale 60,818 — 60,818 Loans held for investment 6,771,080 — 6,771,080 Loans held for investment - Warehouse Purchase Program 1,693,049 — 1,693,049 Bank premises and equipment 67,347 (1,833 ) 65,514 Other real estate owned 4,876 — 4,876 Core deposit intangibles 60,058 — 60,058 Federal Home Loan Bank stock 117,939 (113 ) 117,826 Bank owned life insurance and other assets 242,592 (7,013 ) 235,579 Total assets acquired 9,719,341 (8,959 ) 9,710,382 Fair value of liabilities assumed: Deposits 6,434,732 — 6,434,732 Other borrowings 2,078,682 — 2,078,682 Securities sold under repurchase agreements 57,670 — 57,670 Trust preferred securities 15,376 — 15,376 Subordinated notes 125,950 — 125,950 Other liabilities 201,472 (666 ) 200,806 Total liabilities assumed 8,913,882 (666 ) 8,913,216 Fair value of net assets acquired $ 805,459 $ (8,293 ) $ 797,166 Goodwill resulting from acquisition $ 1,322,826 $ 8,293 $ 1,331,119
Summary of Pro Forma Information	The following pro forma information presents the results of operations for the three and six months ended June 30, 2019, as if the Merger had occurred on January 1, 2019 (dollars in thousands, except per share amounts). Three Months Ended June 30, 2019 Six Months Ended June 30, 2019 Net interest income $ 270,971 $ 536,218 Net income 131,508 227,277 Basic earnings per share 1.37 2.37 Diluted earnings per share 1.37 2.37

Income Per Common Share - Sched

Income Per Common Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income	$ 130,901	$ 82,258	$ 261,749	$ 164,660
Basic, Weighted average shares outstanding (in shares)	92,658	69,806	93,514	69,832
Basic	$ 1.41	$ 1.18	$ 2.80	$ 2.36
Diluted, Weighted average shares outstanding (in shares)	92,658	69,806	93,514	69,832
Diluted	$ 1.41	$ 1.18	$ 2.80	$ 2.36

Income Per Common Share - Addit

Income Per Common Share - Additional Information (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Number of options outstanding	0		0
Antidilutive Securities excluded from computation of earnings per share, amount	0	0	0	0

New Accounting Standards - Addi

New Accounting Standards - Additional Information (Details) - Accounting Standards Update 2016-13 [Member]	6 Months Ended
	Jun. 30, 2020USD ($)
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Increase in allowance for credit losses for loans	$ 108,700,000
Increase in allowance for credit losses for off-balance sheet credit exposures	24,400,000
Increase in allowance for credit losses for loans	131,800,000
Allowance for credit losses related to debt securities	0
Legacy Texas [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Increase in allowance for credit losses for loans	102,500,000
Increase in allowance for credit losses for off-balance sheet credit exposures	6,300,000
Increase in allowance for credit losses for loans	$ 130,300,000

New Accounting Standards - Sche

New Accounting Standards - Schedule of Impact of Adopting ASU 2016-13 (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	$ 324,205	$ 327,206	$ 328,007	$ 87,469	$ 87,006	$ 86,091	$ 86,440
Allowance for credit losses on off-balance sheet credit exposure	29,947		29,947	5,599
Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			240,538
Allowance for credit losses on off-balance sheet credit exposure			24,348
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	6,898	5,769		2,971	3,816	3,284	3,693
Pre-ASC 326 Adoption [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			87,469
Allowance for credit losses on off-balance sheet credit exposure			5,599
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	39,862	28,741	28,729	14,654	15,886	16,192	15,582
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			14,075
Real Estate [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			5,768
Real Estate [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			2,797
Real Estate [Member] | 1-4 Family [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	33,021	23,539	23,544	15,277	14,383	14,455	14,135
Real Estate [Member] | 1-4 Family [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			8,267
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	78,207	61,403	61,322	12,332	12,166	11,590	11,220
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			48,990
Real Estate [Member] | Pre-ASC 326 Adoption [Member] | Construction, Land Development and Other Land Loans [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			14,654
Real Estate [Member] | Pre-ASC 326 Adoption [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			2,971
Real Estate [Member] | Pre-ASC 326 Adoption [Member] | 1-4 Family [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			15,277
Real Estate [Member] | Pre-ASC 326 Adoption [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			12,332
Commercial and Industrial [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	149,884	180,097	180,069	40,445	39,177	39,059	40,223
Commercial and Industrial [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			139,624
Commercial and Industrial [Member] | Pre-ASC 326 Adoption [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			40,445
Consumer and Other [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	$ 16,333	$ 27,657	28,575	$ 1,790	$ 1,578	$ 1,511	$ 1,587
Consumer and Other [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			26,785
Consumer and Other [Member] | Pre-ASC 326 Adoption [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			$ 1,790

Securities - Schedule of Amorti

Securities - Schedule of Amortized Cost and Fair Value of Investment Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Amortized Cost	$ 311,812	$ 286,901
Available for Sale, Gross Unrealized Gains	790	1,350
Available for Sale, Gross Unrealized Losses	(2,557)	(588)
Available for Sale	310,045	287,663
Held to Maturity, Amortized Cost	7,407,541	8,282,393
Held to Maturity, Gross Unrealized Gains	193,530	56,865
Held to Maturity, Gross Unrealized Losses	(636)	(35,407)
Held to Maturity	7,600,435	8,303,851
States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Amortized Cost	305	470
Available for Sale, Gross Unrealized Gains	1	1
Available for Sale	306	471
Held to Maturity, Amortized Cost	202,340	238,347
Held to Maturity, Gross Unrealized Gains	7,808	7,632
Held to Maturity, Gross Unrealized Losses		(189)
Held to Maturity	210,148	245,790
Collateralized Mortgage Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Amortized Cost	265,422	235,222
Available for Sale, Gross Unrealized Gains	163	690
Available for Sale, Gross Unrealized Losses	(1,870)	(139)
Available for Sale	263,715	235,773
Held to Maturity, Amortized Cost	154,390	203,470
Held to Maturity, Gross Unrealized Gains	2,725	1,115
Held to Maturity, Gross Unrealized Losses	(190)	(373)
Held to Maturity	156,925	204,212
Mortgage-backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Amortized Cost	46,085	51,209
Available for Sale, Gross Unrealized Gains	626	659
Available for Sale, Gross Unrealized Losses	(687)	(449)
Available for Sale	46,024	51,419
Held to Maturity, Amortized Cost	7,046,834	7,826,643
Held to Maturity, Gross Unrealized Gains	182,947	48,060
Held to Maturity, Gross Unrealized Losses	(446)	(34,845)
Held to Maturity	7,229,335	7,839,858
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Schedule Of Available For Sale Securities [Line Items]
Held to Maturity, Amortized Cost	3,977	13,933
Held to Maturity, Gross Unrealized Gains	50	58
Held to Maturity	$ 4,027	$ 13,991

Securities - Additional Informa

Securities - Additional Information (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020USD ($)Security	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)SegmentSecurity	Jun. 30, 2019USD ($)	Dec. 31, 2019USD ($)Security
Schedule Of Held To Maturity Securities [Line Items]
Number of Investment Securities Segments | Segment			2
Credit losses			$ 0
Municipal securities percentage of securities portfolio	2.60%		2.60%
Securities in Unrealized Loss Positions Qualitative Disclosure Number of Positions Greater Than or Equal to One Year | Security	29		29		138
Gain (loss) on sale of securities	$ 0	$ 0	$ 0	$ 0
Available for sale securities, at fair value	310,045,000		310,045,000		$ 287,663,000
Collateralized Securities [Member]
Schedule Of Held To Maturity Securities [Line Items]
Available for Sale Securities, Amortized Cost Basis	5,660,000,000		5,660,000,000		5,980,000,000
Available for sale securities, at fair value	$ 5,800,000,000		$ 5,800,000,000		$ 5,990,000,000
Securities Concentration Risk [Member] | Stockholders' Equity, Total [Member]
Schedule Of Held To Maturity Securities [Line Items]
Concentration Risk, Percentage			10.00%		10.00%

Securities - Securities in Cont

Securities - Securities in Continuous Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Estimated Fair Value, Less than 12 Months	$ 206,738	$ 85,146
Available for Sale, Unrealized Losses, Less than 12 Months	(2,259)	(585)
Available for Sale, Estimated Fair Value, 12 Months or More	15,383	1,828
Available for Sale, Unrealized Losses, 12 Months or More	(298)	(3)
Available for Sale, Estimated Fair Value, Total	222,121	86,974
Available for Sale, Unrealized Losses, Total	(2,557)	(588)
Held to Maturity, Estimated Fair Value, Less than 12 Months	78,547	1,060,533
Held to Maturity, Unrealized Losses, Less than 12 Months	(628)	(3,573)
Held to Maturity, Estimated Fair Value, 12 Months or More	1,443	3,114,006
Held to Maturity, Unrealized Losses, 12 Months or More	(8)	(31,834)
Held to Maturity, Estimated Fair Value, Total	79,990	4,174,539
Held to Maturity, Unrealized Losses, Total	(636)	(35,407)
Collateralized Mortgage Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Estimated Fair Value, Less than 12 Months	189,617	50,245
Available for Sale, Unrealized Losses, Less than 12 Months	(1,859)	(136)
Available for Sale, Estimated Fair Value, 12 Months or More	1,628	1,818
Available for Sale, Unrealized Losses, 12 Months or More	(11)	(3)
Available for Sale, Estimated Fair Value, Total	191,245	52,063
Available for Sale, Unrealized Losses, Total	(1,870)	(139)
Held to Maturity, Estimated Fair Value, Less than 12 Months	40,895	54,890
Held to Maturity, Unrealized Losses, Less than 12 Months	(190)	(373)
Held to Maturity, Estimated Fair Value, Total	40,895	54,890
Held to Maturity, Unrealized Losses, Total	(190)	(373)
Mortgage-backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Estimated Fair Value, Less than 12 Months	17,121	34,901
Available for Sale, Unrealized Losses, Less than 12 Months	(400)	(449)
Available for Sale, Estimated Fair Value, 12 Months or More	13,755	10
Available for Sale, Unrealized Losses, 12 Months or More	(287)
Available for Sale, Estimated Fair Value, Total	30,876	34,911
Available for Sale, Unrealized Losses, Total	(687)	(449)
Held to Maturity, Estimated Fair Value, Less than 12 Months	37,652	947,314
Held to Maturity, Unrealized Losses, Less than 12 Months	(438)	(3,017)
Held to Maturity, Estimated Fair Value, 12 Months or More	1,443	3,110,765
Held to Maturity, Unrealized Losses, 12 Months or More	(8)	(31,828)
Held to Maturity, Estimated Fair Value, Total	39,095	4,058,079
Held to Maturity, Unrealized Losses, Total	$ (446)	(34,845)
States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities [Line Items]
Held to Maturity, Estimated Fair Value, Less than 12 Months		58,329
Held to Maturity, Unrealized Losses, Less than 12 Months		(183)
Held to Maturity, Estimated Fair Value, 12 Months or More		3,241
Held to Maturity, Unrealized Losses, 12 Months or More		(6)
Held to Maturity, Estimated Fair Value, Total		61,570
Held to Maturity, Unrealized Losses, Total		$ (189)

Securities - Investment Securit

Securities - Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Investments Debt And Equity Securities [Abstract]
Held to Maturity, amortized cost, due in one year or less	$ 29,087
Held to Maturity, amortized cost, due after one year through five years	114,383
Held to Maturity, amortized cost, due after five years through ten years	56,229
Held to Maturity, amortized cost, due after ten years	6,618
Held to Maturity, amortized cost, subtotal	206,317
Held to Maturity, amortized cost, mortgage-backed securities and collateralized mortgage obligations	7,201,224
Held to Maturity, Amortized Cost	7,407,541	$ 8,282,393
Held to Maturity, fair value, due in one year or less	29,280
Held to Maturity, fair value, due after one year through five years	119,288
Held to Maturity, fair value, due after five years through ten years	58,779
Held to Maturity, fair value, due after ten years	6,828
Held to Maturity, fair value, subtotal	214,175
Held to Maturity, fair value, mortgage-backed securities and collateralized mortgage obligations	7,386,260
Held to Maturity, fair value, total	7,600,435	8,303,851
Available for Sale, amortized cost, due in one year or less	305
Available for Sale, amortized cost, subtotal	305
Available for Sale, amortized cost, mortgage-backed securities and collateralized mortgage obligations	311,507
Available for Sale, Amortized Cost	311,812	286,901
Available for Sale, fair value, due in one year or less	306
Available for Sale, fair value, subtotal	306
Available for Sale, fair value, mortgage-backed securities and collateralized mortgage obligations	309,739
Available for Sale securities, at fair value	$ 310,045	$ 287,663

Loans and Allowance for Credi_3

Loans and Allowance for Credit Losses - Types of Loans in Loan Portfolio (Details) - USD ($) $ in Thousands		Jun. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans held for sale		$ 39,516	$ 80,959
Total loans held for investment		18,428,474	17,211,625
Total loans, including Warehouse Purchase Program		21,025,173	18,845,346
Residential Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for sale		39,516	80,959
Warehouse Purchase Program [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		2,557,183	1,552,762
Total loans, including Warehouse Purchase Program		2,557,183	1,552,762
Commercial and Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		4,227,102	3,205,595
Total loans, including Warehouse Purchase Program		4,227,102	3,205,595
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		2,033,037	2,064,167
Total loans, including Warehouse Purchase Program		2,033,037	2,064,167
Real Estate [Member] | 1-4 Family [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		4,582,554	4,306,452
Total loans, including Warehouse Purchase Program	[1]	4,622,070	4,387,411
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		6,550,086	6,556,285
Total loans, including Warehouse Purchase Program		6,550,086	6,556,285
Real Estate [Member] | Farmland [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		429,963	495,558
Agriculture [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		182,731	185,297
Consumer and Other [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		423,001	398,271
Total loans, including Warehouse Purchase Program		$ 423,001	$ 398,271
[1]	Includes $39.5 million and $81.0 million of residential mortgage loans held for sale at June 30, 2020 and December 31, 2019, respectively.

Loans and Allowance for Credi_4

Loans and Allowance for Credit Losses - Additional Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020USD ($)contract	Jun. 30, 2019USD ($)contract	Jan. 01, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Accounts Notes And Loans Receivable [Line Items]
Percentage of Loans Related to Single Industry on Loans	10.00%			10.00%
Percentage of real estate loans aggregating to company loan portfolio, excluding Warehouse Purchase Program loans	71.30%
Loans and Leases Receivable, Related Parties	$ 4,853			$ 4,152	$ 1,923
Loans held for investment	$ 18,428,474			$ 17,211,625
Financing Receivable Ratio of Nonperforming Loans to All Loans and Other Real Estate	0.37%			0.33%
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	$ 1,400	$ 1,200
Loans and leases receivable, nonaccrual loans	62,900	$ 37,300
Financing Receivable, Allowance for Credit Losses on Loans	$ 324,200			$ 87,500
Allowance for Credit Losses as Percentage of Loans	1.54%			0.46%
Allowance for credit losses on off-balance sheet credit exposure	$ 29,947		$ 29,947	$ 5,599
Commitments expected to fund	1,770,000
Nonaccrual loans	$ 62,904			55,243
Troubled debt restructurings, number of loans | contract	1	1
Financing receivable, number of loans with default | contract	0
Financing receivable, modifications, recorded investment	$ 13	$ 14,300
Troubled debt restructuring, recorded investment at date of restructure	$ 23	14,783
Loan to be Considered as Payment Default in Period	90 days
Troubled Debt Restructuring [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses on off-balance sheet credit exposure	$ 29,900			5,600
Nonaccrual loans	13,600	$ 14,300
Accounting Standards Update 2016-13 [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses on off-balance sheet credit exposure			$ 24,348
Accounting Standards Update 2016-13 [Member] | PCD Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
PCD discount reallocated to allowance for credit losses				131,800
Nonperforming Financial Instruments [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 77,900			$ 62,900

Loans and Allowance for Credi_5

Loans and Allowance for Credit Losses - Related Party Loans (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Receivables [Abstract]
Beginning balance on January 1	$ 4,152	$ 1,923
New loans	810	1
Transfers		2,500
Repayments	(109)	(272)
Ending balance	$ 4,853	$ 4,152

Loans and Allowance for Credi_6

Loans and Allowance for Credit Losses - Aging Analysis of Past Due Loans (Details) - USD ($) $ in Thousands		Jun. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		$ 58,524	$ 80,887
Nonaccrual loans		62,904	55,243
Current loans		20,903,745	18,709,216
Total loans		21,025,173	18,845,346
Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		49,833	80,446
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		8,691	441
Warehouse Purchase Program Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Current loans		2,557,183	1,552,762
Total loans		2,557,183	1,552,762
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		3,008	466
Nonaccrual loans		769	103
Current loans		608,917	680,286
Total loans		612,694	680,855
Agriculture and Agriculture Real Estate (Includes Farmland) [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		3,008	466
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		22,133	16,470
Nonaccrual loans		2,243	1,142
Current loans		2,008,661	2,046,555
Total loans		2,033,037	2,064,167
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		13,846	16,470
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		8,287
Real Estate [Member] | 1-4 Family Residential (Includes Home Equity) [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing	[1]	9,141	44,325
Nonaccrual loans	[1]	29,642	24,413
Current loans	[1]	4,583,287	4,318,673
Total loans	[1]	4,622,070	4,387,411
Real Estate [Member] | 1-4 Family Residential (Includes Home Equity) [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing	[1]	9,098	43,884
Real Estate [Member] | 1-4 Family Residential (Includes Home Equity) [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing	[1]	43	441
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		8,200	10,669
Nonaccrual loans		15,129	12,714
Current loans		6,526,757	6,532,902
Total loans		6,550,086	6,556,285
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		7,881	10,669
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		319
Commercial and Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		12,110	7,249
Nonaccrual loans		15,057	16,809
Current loans		4,199,935	3,181,537
Total loans		4,227,102	3,205,595
Commercial and Industrial [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		12,085	7,249
Commercial and Industrial [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		25
Consumer and Other [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		3,932	1,708
Nonaccrual loans		64	62
Current loans		419,005	396,501
Total loans		423,001	398,271
Consumer and Other [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		3,915	$ 1,708
Consumer and Other [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		$ 17
[1]	Includes $39.5 million and $81.0 million of residential mortgage loans held for sale at June 30, 2020 and December 31, 2019, respectively.

Loans and Allowance for Credi_7

Loans and Allowance for Credit Losses - Aging Analysis of Past Due Loans (Parenthetical) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans held for sale	$ 39,516	$ 80,959
Residential Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for sale	$ 39,516	$ 80,959

Loans and Allowance for Credi_8

Loans and Allowance for Credit Losses - Nonperforming Assets (Details) - USD ($) $ in Thousands		Jun. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		$ 18,428,474	$ 17,211,625
Other real estate owned		$ 6,160	$ 6,936
Nonperforming assets to total loans and other real estate		0.37%	0.33%
Nonperforming assets to total loans, excluding Warehouse Purchase Program loans, and other real estate		0.42%	0.36%
Nonperforming Financial Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		$ 71,595	$ 55,684
Repossessed assets		187	323
Other real estate owned		6,160	6,936
Total nonperforming assets		77,942	62,943
Nonperforming Financial Loans [Member] | Finance Receivable Nonaccrual Status [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	[1],[2]	62,904	55,243
Nonperforming Financial Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		$ 8,691	$ 441
[1]	Includes troubled debt restructurings of $13.6 million as of both June 30, 2020 and December 31, 2019.
[2]	There were no nonperforming or troubled debt restructurings of warehouse lines of credit or Warehouse Purchase Program loans for the periods presented.

Loans and Allowance for Credi_9

Loans and Allowance for Credit Losses - Nonperforming Assets (Parenthetical) (Details) - USD ($)		Jun. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		$ 18,428,474,000	$ 17,211,625,000
Nonperforming Financial Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		71,595,000	55,684,000
Nonperforming Financial Loans [Member] | Finance Receivable Nonaccrual Status [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	[1],[2]	62,904,000	55,243,000
Troubled Debt Restructuring [Member] | Nonperforming Financial Loans [Member] | Finance Receivable Nonaccrual Status [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		13,600,000	13,600,000
Troubled Debt Restructuring [Member] | Nonperforming Financial Loans [Member] | Finance Receivable Nonaccrual Status [Member] | Warehouse Purchase Program [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		$ 0	$ 0
[1]	Includes troubled debt restructurings of $13.6 million as of both June 30, 2020 and December 31, 2019.
[2]	There were no nonperforming or troubled debt restructurings of warehouse lines of credit or Warehouse Purchase Program loans for the periods presented.

Loans and Allowance for Cred_10

Loans and Allowance for Credit Losses - Recorded Investment and Outstanding Balance for Purchased Credit Deteriorated Loans and Non Purchased Credit Deteriorated Loans (Details) - USD ($) $ in Thousands		Jun. 30, 2020	Dec. 31, 2019
PCD Loans [Member]
Purchased And Non Purchased Credit Impaired Loans [Line Items]
Outstanding balance		$ 290,189	$ 410,785
Discount	[1]	(22,565)	(167,320)	[2]
Recorded investment		267,624	243,465
Non-PCD Loans [Member]
Purchased And Non Purchased Credit Impaired Loans [Line Items]
Outstanding balance		5,117,679	6,102,540
Discount		(69,860)	(110,130)
Recorded investment		$ 5,047,819	$ 5,992,410
[1]	ASU 2016-13 became effective for the Company on January 1, 2020.
[2]	Includes $131.8 million in PCD loans credit discount.

Loans and Allowance for Cred_11

Loans and Allowance for Credit Losses - Recorded Investment and Outstanding Balance for Purchased Credit Deteriorated Loans and Non Purchased Credit Deteriorated Loans (Parenthetical) (Details) $ in Millions	Dec. 31, 2019USD ($)
PCD Loans [Member]
Purchased And Non Purchased Credit Impaired Loans [Line Items]
PCD loans credit discount	$ 131.8

Loans and Allowance for Cred_12

Loans and Allowance for Credit Losses - Summary of Changes in Accretable Yields of Acquired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
PCD Loans [Member]
Changes In Accretable Yield for PCI And Non PCI Loans [Line Items]
Balance at beginning of period	$ 29,460	$ 1,234	$ 35,654	$ 1,534
Adjustments	(274)	17	(449)	36
Accretion charge-offs	(354)		(354)
Accretion	(6,267)	(347)	(12,286)	(666)
Balance at June 30,	22,565	904	22,565	904
Non-PCD Loans [Member]
Changes In Accretable Yield for PCI And Non PCI Loans [Line Items]
Balance at beginning of period	87,613	13,359	110,130	14,833
Adjustments	312		312
Accretion charge-offs	(66)		(120)
Accretion	(17,999)	(880)	(40,462)	(2,354)
Balance at June 30,	$ 69,860	$ 12,479	$ 69,860	$ 12,479

Loans and Allowance for Cred_13

Loans and Allowance for Credit Losses - Risk Grade and Category of Loan (Details) $ in Thousands	Jun. 30, 2020USD ($)
Financing Receivable Impaired [Line Items]
2020	$ 5,483,424
2019	3,359,378
2018	2,616,787
2017	2,297,395
2016	1,607,533
Prior	3,640,541
Revolving Loans	1,589,888
Revolving Loans Converted to Term Loans	430,227
Total	21,025,173
PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2020	790
2019	45,842
2018	13,374
2017	41,463
2016	3,833
Prior	72,241
Revolving Loans	66,808
Revolving Loans Converted to Term Loans	23,273
Total	267,624
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020	81,367
2019	104,992
2018	77,903
2017	53,086
2016	62,498
Prior	137,743
Revolving Loans	93,547
Revolving Loans Converted to Term Loans	1,558
Total	612,694
Agriculture and Agriculture Real Estate (Includes Farmland) [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2019	217
Prior	1,294
Revolving Loans Converted to Term Loans	306
Total	1,817
Warehouse Purchase Program [Member]
Financing Receivable Impaired [Line Items]
2020	2,557,183
Total	2,557,183
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2020	351,619
2019	720,940
2018	451,687
2017	230,074
2016	45,499
Prior	100,936
Revolving Loans	130,645
Revolving Loans Converted to Term Loans	1,637
Total	2,033,037
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2019	1,305
2017	397
Prior	6,859
Total	8,561
Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020	646,666
2019	924,859
2018	630,095
2017	551,744
2016	526,947
Prior	1,188,841
Revolving Loans	147,726
Revolving Loans Converted to Term Loans	5,192
Total	4,622,070
Real Estate [Member] | 1-4 Family [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2016	251
Prior	5,300
Revolving Loans	1,040
Total	6,591
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020	215,778
2019	1,087,837
2018	1,145,470
2017	1,235,620
2016	830,713
Prior	1,905,314
Revolving Loans	88,580
Revolving Loans Converted to Term Loans	40,774
Total	6,550,086
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2019	15,329
2018	5,094
2017	27,440
Prior	53,273
Total	101,136
Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020	1,567,972
2019	439,375
2018	268,061
2017	163,202
2016	131,299
Prior	263,531
Revolving Loans	1,012,941
Revolving Loans Converted to Term Loans	380,721
Total	4,227,102
Commercial and Industrial [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2020	790
2019	28,991
2018	8,280
2017	11,746
2016	3,582
Prior	1,715
Revolving Loans	49,350
Revolving Loans Converted to Term Loans	22,967
Total	127,421
Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020	62,839
2019	81,375
2018	43,571
2017	63,669
2016	10,577
Prior	44,176
Revolving Loans	116,449
Revolving Loans Converted to Term Loans	345
Total	423,001
Consumer and Other [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2017	1,880
Prior	3,800
Revolving Loans	16,418
Total	22,098
Grade 1 [Member]
Financing Receivable Impaired [Line Items]
2020	1,406,121
2019	19,053
2018	13,280
2017	8,624
2016	4,219
Prior	14,232
Revolving Loans	31,962
Revolving Loans Converted to Term Loans	26
Total	1,497,517
Grade 1 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020	695
2019	380
2018	308
2017	255
2016	103
Prior	526
Revolving Loans	10,100
Total	12,367
Grade 1 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
Prior	27
Total	27
Grade 1 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020	98
Total	98
Grade 1 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020	1,379,014
2019	8,123
2018	7,034
2017	3,487
2016	1,597
Prior	7,345
Revolving Loans	20,344
Revolving Loans Converted to Term Loans	23
Total	1,426,967
Grade 1 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020	26,314
2019	10,550
2018	5,938
2017	4,882
2016	2,519
Prior	6,334
Revolving Loans	1,518
Revolving Loans Converted to Term Loans	3
Total	58,058
Grade 2 [Member]
Financing Receivable Impaired [Line Items]
2020	9,097
2019	12,997
2018	1,676
2017	48,487
2016	2,260
Prior	20,454
Revolving Loans	23,684
Revolving Loans Converted to Term Loans	62,772
Total	181,427
Grade 2 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020	10
2017	355
Prior	1,591
Revolving Loans	40
Total	1,996
Grade 2 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2017	88
2016	132
Prior	281
Total	501
Grade 2 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2019	71
2018	121
2017	728
2016	260
Prior	11,068
Revolving Loans	1,335
Total	13,583
Grade 2 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020	5,743
2019	2,008
2017	7,480
2016	193
Prior	4,980
Total	20,404
Grade 2 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020	999
2019	155
2018	1,137
2017	1,530
2016	1,442
Prior	1,132
Revolving Loans	21,124
Revolving Loans Converted to Term Loans	62,772
Total	90,291
Grade 2 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020	2,345
2019	10,763
2018	418
2017	38,306
2016	233
Prior	1,402
Revolving Loans	1,185
Total	54,652
Grade 3 [Member]
Financing Receivable Impaired [Line Items]
2020	4,011,994
2019	3,125,230
2018	2,384,054
2017	1,871,510
2016	1,368,824
Prior	2,947,589
Revolving Loans	1,276,923
Revolving Loans Converted to Term Loans	312,477
Total	17,298,601
Grade 3 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020	68,790
2019	90,926
2018	71,576
2017	49,393
2016	57,106
Prior	110,608
Revolving Loans	75,452
Revolving Loans Converted to Term Loans	1,252
Total	525,103
Grade 3 [Member] | Warehouse Purchase Program [Member]
Financing Receivable Impaired [Line Items]
2020	2,557,183
Total	2,557,183
Grade 3 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2020	345,184
2019	702,893
2018	417,348
2017	116,076
2016	38,311
Prior	74,496
Revolving Loans	120,229
Revolving Loans Converted to Term Loans	1,637
Total	1,816,174
Grade 3 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020	644,503
2019	909,952
2018	610,756
2017	532,702
2016	512,549
Prior	1,114,277
Revolving Loans	139,042
Revolving Loans Converted to Term Loans	5,022
Total	4,468,803
Grade 3 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020	188,791
2019	1,035,743
2018	1,022,056
2017	1,037,919
2016	641,974
Prior	1,432,384
Revolving Loans	73,808
Revolving Loans Converted to Term Loans	40,429
Total	5,473,104
Grade 3 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020	173,841
2019	331,439
2018	226,143
2017	116,920
2016	111,163
Prior	185,271
Revolving Loans	792,523
Revolving Loans Converted to Term Loans	263,799
Total	2,201,099
Grade 3 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020	33,702
2019	54,277
2018	36,175
2017	18,500
2016	7,721
Prior	30,553
Revolving Loans	75,869
Revolving Loans Converted to Term Loans	338
Total	257,135
Grade 4 [Member]
Financing Receivable Impaired [Line Items]
2020	41,108
2019	131,165
2018	194,250
2017	309,407
2016	192,010
Prior	518,923
Revolving Loans	109,585
Revolving Loans Converted to Term Loans	29,434
Total	1,525,882
Grade 4 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020	8,750
2019	9,697
2018	4,798
2017	3,083
2016	5,099
Prior	22,535
Revolving Loans	5,912
Total	59,874
Grade 4 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2020	6,435
2019	16,742
2018	33,221
2017	113,509
2016	7,056
Prior	13,771
Revolving Loans	9,682
Total	200,416
Grade 4 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020	1,980
2019	12,884
2018	18,229
2017	13,841
2016	10,496
Prior	38,260
Revolving Loans	2,722
Revolving Loans Converted to Term Loans	138
Total	98,550
Grade 4 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020	13,295
2019	34,582
2018	114,906
2017	149,851
2016	157,957
Prior	391,781
Revolving Loans	13,272
Revolving Loans Converted to Term Loans	345
Total	875,989
Grade 4 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020	10,170
2019	53,041
2018	22,132
2017	29,046
2016	11,293
Prior	50,492
Revolving Loans	66,940
Revolving Loans Converted to Term Loans	28,947
Total	272,061
Grade 4 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020	478
2019	4,219
2018	964
2017	77
2016	109
Prior	2,084
Revolving Loans	11,057
Revolving Loans Converted to Term Loans	4
Total	18,992
Grade 5 [Member]
Financing Receivable Impaired [Line Items]
2020	4,711
2019	20,396
2018	3,838
2017	14,325
2016	13,104
Prior	24,520
Revolving Loans	20,013
Revolving Loans Converted to Term Loans	114
Total	101,021
Grade 5 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020	1,654
2019	3,419
2018	1,130
Prior	648
Revolving Loans	2,043
Total	8,894
Grade 5 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2017	4
Prior	2,910
Total	2,914
Grade 5 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2019	164
2017	1,258
2016	232
Prior	4,082
Total	5,736
Grade 5 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2018	2,164
2017	12,888
2016	12,575
Prior	14,521
Total	42,148
Grade 5 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020	3,057
2019	16,813
2018	476
2017	157
2016	297
Prior	2,359
Revolving Loans	7,568
Revolving Loans Converted to Term Loans	114
Total	30,841
Grade 5 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2018	68
2017	18
Revolving Loans	10,402
Total	10,488
Grade 6 [Member]
Financing Receivable Impaired [Line Items]
2020	9,582
2019	1,994
2018	3,804
2017	560
2016	4,670
Prior	14,970
Revolving Loans	24,942
Revolving Loans Converted to Term Loans	682
Total	61,204
Grade 6 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020	1,468
2018	59
2016	186
Prior	184
Total	1,897
Grade 6 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
Prior	2,202
Total	2,202
Grade 6 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020	85
2019	42
2018	3
2017	328
Prior	2,165
Revolving Loans Converted to Term Loans	32
Total	2,655
Grade 6 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020	7,928
2019	175
2018	1,250
2017	26
2016	3,218
Prior	8,165
Revolving Loans	1,500
Total	22,262
Grade 6 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020	101
2019	243
2018	2,492
2017	206
2016	1,266
Prior	2,254
Revolving Loans	23,442
Revolving Loans Converted to Term Loans	650
Total	30,654
Grade 6 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2019	1,534
Total	1,534
Grade 7 [Member]
Financing Receivable Impaired [Line Items]
2020	21
2019	2,701
2018	2,511
2017	3,019
2016	18,603
Prior	27,513
Revolving Loans	35,971
Revolving Loans Converted to Term Loans	1,449
Total	91,788
Grade 7 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2019	353
2018	32
2016	4
Prior	357
Total	746
Grade 7 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2018	1,118
Prior	390
Revolving Loans	734
Total	2,242
Grade 7 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2019	1,746
2018	986
2017	2,887
2016	3,159
Prior	13,590
Revolving Loans	3,587
Total	25,955
Grade 7 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020	21
2017	16
2016	14,796
Prior	210
Total	15,043
Grade 7 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2019	570
2018	367
2017	110
2016	649
Prior	12,963
Revolving Loans	31,650
Revolving Loans Converted to Term Loans	1,449
Total	47,758
Grade 7 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2019	32
2018	8
2017	6
2016	(5)
Prior	3
Total	44
Grade 8 [Member]
Financing Receivable Impaired [Line Items]
2016	10
Prior	99
Total	109
Grade 8 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
Prior	99
Total	99
Grade 8 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2016	10
Total	$ 10

Loans and Allowance for Cred_14

Loans and Allowance for Credit Losses - Risk Grade and Category of Loan (Parenthetical) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable Impaired [Line Items]
Loans held for sale	$ 39,516	$ 80,959
Residential Mortgage Loans [Member]
Financing Receivable Impaired [Line Items]
Loans held for sale	$ 39,516	$ 80,959

Loans and Allowance for Cred_15

Loans and Allowance for Credit Losses - Allowance for Credit Losses on Loans by Category of Loan (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Allowance for credit losses:
Allowance for credit losses, beginning balance	$ 327,206	$ 86,091	$ 87,469	$ 86,440
Provision for credit losses	10,000	800	10,000	1,500
Charge-offs	(13,976)	(1,119)	(15,963)	(4,028)
Recoveries	975	1,234	2,161	3,094
Net charge-offs	(13,001)	115	(13,802)	(934)
Allowance for credit losses, ending balance	324,205	87,006	324,205	87,006
Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	240,538		240,538
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	5,769	3,284	2,971	3,693
Provision for credit losses	1,126	578	1,126	(1,109)
Charge-offs	(32)	(54)	(62)	(64)
Recoveries	35	8	66	1,296
Net charge-offs	3	(46)	4	1,232
Allowance for credit losses, ending balance	6,898	3,816	6,898	3,816
Agriculture and Agriculture Real Estate (Includes Farmland) [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	2,797		2,797
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	28,741	16,192	14,654	15,582
Provision for credit losses	11,115	(299)	11,115	311
Charge-offs		(19)		(63)
Recoveries	6	12	18	56
Net charge-offs	6	(7)	18	(7)
Allowance for credit losses, ending balance	39,862	15,886	39,862	15,886
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	14,075		14,075
Real Estate [Member] | 1-4 Family [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	23,539	14,455	15,277	14,135
Provision for credit losses	9,533	(61)	9,533	256
Charge-offs	(145)	(16)	(175)	(22)
Recoveries	94	5	119	14
Net charge-offs	(51)	(11)	(56)	(8)
Allowance for credit losses, ending balance	33,021	14,383	33,021	14,383
Real Estate [Member] | 1-4 Family [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	8,267		8,267
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	61,403	11,590	12,332	11,220
Provision for credit losses	16,804	575	16,804	944
Recoveries		1	81	2
Net charge-offs		1	81	2
Allowance for credit losses, ending balance	78,207	12,166	78,207	12,166
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	48,990		48,990
Commercial and Industrial [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	180,097	39,059	40,445	40,223
Provision for credit losses	(18,007)	(710)	(18,007)	(155)
Charge-offs	(12,678)	(125)	(13,289)	(2,082)
Recoveries	472	953	1,111	1,191
Net charge-offs	(12,206)	828	(12,178)	(891)
Allowance for credit losses, ending balance	149,884	39,177	149,884	39,177
Commercial and Industrial [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	139,624		139,624
Consumer and Other [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	27,657	1,511	1,790	1,587
Provision for credit losses	(10,571)	717	(10,571)	1,253
Charge-offs	(1,121)	(905)	(2,437)	(1,797)
Recoveries	368	255	766	535
Net charge-offs	(753)	(650)	(1,671)	(1,262)
Allowance for credit losses, ending balance	16,333	$ 1,578	16,333	$ 1,578
Consumer and Other [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	$ 26,785		$ 26,785

Loans and Allowance for Cred_16

Loans and Allowance for Credit Losses - Troubled Debt Restructurings (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020USD ($)contract	Jun. 30, 2019USD ($)contract
Financing Receivable Modifications [Line Items]
Troubled debt restructurings, number of loans | contract	1	1
Troubled debt restructurings, pre-modification outstanding recorded investment	$ 23	$ 14,783
Troubled debt restructurings, post-modification outstanding recorded investment	$ 13	$ 14,258
Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Modifications [Line Items]
Troubled debt restructurings, number of loans | contract	1
Troubled debt restructurings, pre-modification outstanding recorded investment	$ 23
Troubled debt restructurings, post-modification outstanding recorded investment	$ 13
Commercial and Industrial [Member]
Financing Receivable Modifications [Line Items]
Troubled debt restructurings, number of loans | contract		1
Troubled debt restructurings, pre-modification outstanding recorded investment		$ 14,783
Troubled debt restructurings, post-modification outstanding recorded investment		$ 14,258

Fair Value - Fair Value Assets

Fair Value - Fair Value Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Available for sale securities:
Available for sale securities, at fair value	$ 310,045	$ 287,663
Fair Value, Measurements, Recurring [Member]
Available for sale securities:
Available for sale securities, at fair value	310,045	287,663
Fair Value, Measurements, Recurring [Member] | Loan Customer Counterparty [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value	14,374	4,829
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value		240
Fair Value, Measurements, Recurring [Member] | Financial Institution Counterparty [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		240
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value	14,374	4,829
Fair Value, Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		305
Fair Value, Measurements, Recurring [Member] | Forward Mortgage-Backed Securities Trades [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		3
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value		83
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Available for sale securities:
Available for sale securities, at fair value	310,045	287,663
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Loan Customer Counterparty [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value	14,374	4,829
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value		240
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Financial Institution Counterparty [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		240
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value	14,374	4,829
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Interest Rate Lock Commitments [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		305
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Forward Mortgage-Backed Securities Trades [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		3
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value		83
Fair Value, Measurements, Recurring [Member] | States and Political Subdivisions [Member]
Available for sale securities:
Available for sale securities, at fair value	306	471
Fair Value, Measurements, Recurring [Member] | States and Political Subdivisions [Member] | Level 2 [Member]
Available for sale securities:
Available for sale securities, at fair value	306	471
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member]
Available for sale securities:
Available for sale securities, at fair value	263,715	235,773
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member] | Level 2 [Member]
Available for sale securities:
Available for sale securities, at fair value	263,715	235,773
Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities [Member]
Available for sale securities:
Available for sale securities, at fair value	46,024	51,419
Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities [Member] | Level 2 [Member]
Available for sale securities:
Available for sale securities, at fair value	$ 46,024	$ 51,419

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Other real estate, additions	$ 732	$ 844
Real estate owned outstanding	732	800
Additions to impaired loans	5,900	17,400
Impaired loans outstanding	$ 5,900	$ 17,400

Fair Value - Summary of Carryin

Fair Value - Summary of Carrying and Fair Value Information of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets
Cash and due from banks	$ 332,873	$ 573,589
Federal funds sold	568	519
Held to maturity securities	7,600,435	8,303,851
Loans held for sale	39,516	80,959
Loans held for investment	18,428,474	17,211,625
Other real estate owned	6,160	6,936
Liabilities
Noninterest-bearing	9,040,257	7,763,894
Interest-bearing	17,112,431	16,435,838
Other borrowings	103,131	1,303,730
Securities sold under repurchase agreements	365,335	377,294
Subordinated notes	125,365	125,804
Carrying Amount [Member]
Assets
Cash and due from banks	332,873	573,589
Federal funds sold	568	519
Held to maturity securities	7,407,541	8,282,393
Loans held for sale	39,516	80,959
Loans held for investment, net of allowance	18,104,269	17,124,156
Other real estate owned	6,160	6,936
Liabilities
Noninterest-bearing	9,040,257	7,763,894
Interest-bearing	17,112,431	16,435,838
Other borrowings	103,131	1,303,730
Securities sold under repurchase agreements	365,335	377,294
Subordinated notes	125,365	125,804
Carrying Amount [Member] | Warehouse Purchase Program [Member]
Assets
Loans held for investment	2,557,183	1,552,762
Estimated Fair Value [Member]
Assets
Cash and due from banks	332,873	573,589
Federal funds sold	568	519
Held to maturity securities	7,600,435	8,303,851
Loans held for sale	39,516	80,959
Loans held for investment, net of allowance	18,046,191	17,045,523
Other real estate owned	6,160	6,936
Liabilities
Noninterest-bearing	9,040,257	7,763,894
Interest-bearing	17,141,559	16,437,453
Other borrowings	103,373	1,303,941
Securities sold under repurchase agreements	365,368	377,302
Subordinated notes	126,175	125,743
Estimated Fair Value [Member] | Level 1 [Member]
Assets
Cash and due from banks	332,873	573,589
Federal funds sold	568	519
Estimated Fair Value [Member] | Level 2 [Member]
Assets
Held to maturity securities	7,600,435	8,303,851
Loans held for sale	39,516	80,959
Other real estate owned	6,160	6,936
Liabilities
Noninterest-bearing	9,040,257	7,763,894
Interest-bearing	17,141,559	16,437,453
Other borrowings	103,373	1,303,941
Securities sold under repurchase agreements	365,368	377,302
Subordinated notes	126,175	125,743
Estimated Fair Value [Member] | Level 3 [Member]
Assets
Loans held for investment, net of allowance	18,046,191	17,045,523
Estimated Fair Value [Member] | Warehouse Purchase Program [Member]
Assets
Loans held for investment	2,557,183	1,552,762
Estimated Fair Value [Member] | Warehouse Purchase Program [Member] | Level 2 [Member]
Assets
Loans held for investment	$ 2,557,183	$ 1,552,762

Goodwill and Core Deposit Int_3

Goodwill and Core Deposit Intangibles - Goodwill and Core Deposit Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill, Beginning balance			$ 3,223,671	$ 1,900,845	$ 1,900,845
Goodwill, LegacyTexas Merger					1,322,826
Goodwill, Ending balance	$ 3,231,964		3,231,964		3,223,671
Goodwill, Measurement period adjustment of LegacyTexas Merger			8,293
Core Deposit Intangibles, Beginning balance			86,404	32,883	32,883
Core Deposit Intangibles, Amortization	(3,293)	$ (1,265)	(6,656)	$ (2,584)	(6,537)
Core Deposit Intangibles, LegacyTexas Merger					60,058
Core Deposit Intangibles, Ending balance	$ 79,748		$ 79,748		$ 86,404

Goodwill and Core Deposit Int_4

Goodwill and Core Deposit Intangibles - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Schedule Of Intangible Assets And Goodwill [Line Items]
Impairment recorded on goodwill and core deposit intangibles			$ 0
Amortization expense related to intangible assets	$ 3,293,000	$ 1,265,000	$ 6,656,000	$ 2,584,000	$ 6,537,000
Minimum [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Finite-lived intangible assets, useful life			10 years
Maximum [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Finite-lived intangible assets, useful life			15 years

Goodwill and Core Deposit Int_5

Goodwill and Core Deposit Intangibles - Estimated Aggregate Future Amortization Expense for Core Deposit Intangibles (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Remaining 2020	$ 6,513
2021	11,551
2022	10,336
2023	9,360
2024	8,699
Thereafter	33,289
Total	$ 79,748	$ 86,404	$ 32,883

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense	$ 9,361	$ 20,917	$ 44,191	$ 42,299
Increase (decrease) in income tax expense	$ (11,600)		$ 1,900
Increase (decrease) in income tax expense, Percentage	(55.20%)		4.50%
Income taxes receivable, net operating loss, CARES Act.			$ 20,100
Effective income tax rate	6.70%	20.60%	14.40%	20.40%
Effective income tax rate reconciliation, at federal statutory income tax rate, percent			21.00%		35.00%
Decrease in deferred tax asset			$ 30,200

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020USD ($)Planshares	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)Planshares	Jun. 30, 2019USD ($)	Dec. 31, 2012shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock-based employee compensation plans | Plan	2		2
Total unrecognized compensation expense related to stock-based compensation arrangements | $	$ 12		$ 12
Weighted-average period of cost expected to be recognized			1 year 8 months 12 days
Number of shares outstanding	0		0
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense | $	$ 3	$ 2.3	$ 6.3	$ 5.1
2020 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares authorized for issuance	2,500,000		2,500,000
Number of restricted shares granted			12,500
2012 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares authorized for issuance					1,250,000
Number of restricted shares granted			502,312
Shares issued			357,313

Contractual Obligations and O_3

Contractual Obligations and Off-Balance Sheet Items - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jan. 01, 2020	Dec. 31, 2019
Contractual Obligations And Off Balance Sheet Items [Line Items]
Operating lease, right-of-use asset	$ 52,000		$ 52,000
Operating lease, liability	$ 52,000		$ 52,000
Operating lease, weighted average remaining lease term	7 years 7 months 6 days		7 years 7 months 6 days
Operating lease, weighted average discount rate, percent	2.43%		2.43%
Operating lease, payments	$ 3,600	$ 1,400	$ 7,200	$ 2,800
Right-of-Use asset obtained in exchange for operating lease liability			1,500
Allowance for credit losses on off-balance sheet credit exposure	29,947		$ 29,947		$ 29,947	$ 5,599
Minimum [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
Lessee operating lease remaining lease term			1 year
Maximum [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
Lessee operating lease remaining lease term			18 years
Subordinated Notes Payable [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
Interest payable	29,100		$ 29,100
Federal Home Loan Bank Advance And Notes Payable [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
Interest payable	$ 245		$ 245

Contractual Obligations and O_4

Contractual Obligations and Off-Balance Sheet Items - Contractual Obligations and Other Commitments (Details) - Lease Total [Member] $ in Thousands	Jun. 30, 2020USD ($)
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	$ 107,517
More than 1 year but less than 3 years	11,791
3 years or more but less than 5 years	10,917
5 years or more	127,569
Total	257,794
Subordinated Notes Payable [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	5,920
More than 1 year but less than 3 years	10,475
3 years or more but less than 5 years	10,475
5 years or more	127,548
Total	154,418
Federal Home Loan Bank Advance And Notes Payable [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	101,597
More than 1 year but less than 3 years	1,316
3 years or more but less than 5 years	442
5 years or more	21
Total	$ 103,376

Contractual Obligations and O_5

Contractual Obligations and Off-Balance Sheet Items - Future Undiscounted Cash Payments Associated with its Operating Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Remaining 2020	$ 4,604
2021	9,523	$ 9,169
2022	8,998	8,641
2023	8,250	7,998
2024	7,369	7,119
2025	6,978
Thereafter	18,247
Total undiscounted lease payments	$ 63,969	$ 68,060

Contractual Obligations and O_6

Contractual Obligations and Off-Balance Sheet Items - Summary of Non-Cancelable Future Operating Lease Commitments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Leases [Abstract]
2020		$ 10,137
2021	$ 9,523	9,169
2022	8,998	8,641
2023	8,250	7,998
2024	7,369	7,119
Thereafter		24,996
Total undiscounted lease payments	$ 63,969	$ 68,060

Contractual Obligations and O_7

Contractual Obligations and Off-Balance Sheet Items - Summary of Commitments Associated with Outstanding Standby Letters of Credit and Commitments to Extend Credit (Details) - Guarantee Obligations [Member] $ in Thousands	Jun. 30, 2020USD ($)
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	$ 2,596,716
More than 1 year but less than 3 years	1,720,453
3 years or more but less than 5 years	592,973
5 years or more	1,265,829
Total	6,175,971
Unused capacity on Warehouse Purchase Program loans [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	690,817
Total	690,817
Commitments to Extend Credit [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	1,798,300
More than 1 year but less than 3 years	1,711,257
3 years or more but less than 5 years	591,779
5 years or more	1,265,829
Total	5,367,165
Standby Letters of Credit [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	107,599
More than 1 year but less than 3 years	9,196
3 years or more but less than 5 years	1,194
5 years or more	0
Total	$ 117,989

Other Comprehensive Income - Ta

Other Comprehensive Income - Tax Effects Allocated to Each Component of Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity [Abstract]
Change in unrealized gain during period, before tax amount	$ 1,654	$ 716	$ (2,529)	$ 1,219
Change in unrealized gain during period, tax effect	(347)	(150)	531	(256)
Change in unrealized gain during period, net of tax amount	1,307	566	(1,998)	963
Total securities available for sale, before tax amount	1,654	716	(2,529)	1,219
Total securities available for sale, tax effect	(347)	(150)	531	(256)
Total securities available for sale, net of tax amount	1,307	566	(1,998)	963
Total other comprehensive (loss) income, before tax amount	1,654	716	(2,529)	1,219
Total other comprehensive (loss) income, tax effect	(347)	(150)	531	(256)
Other comprehensive income (loss), net of tax	$ 1,307	$ 566	$ (1,998)	$ 963

Other Comprehensive Income - Ac

Other Comprehensive Income - Activity in Accumulated Other Comprehensive Income Associated with Securities Available for Sale, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Beginning balance, accumulated other comprehensive income			$ 602	$ 310
Other comprehensive income (loss)	$ 1,307	$ 566	(1,998)	963
Ending balance, accumulated other comprehensive income	(1,396)	1,273	(1,396)	1,273
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Beginning balance, accumulated other comprehensive income			602	310
Other comprehensive income (loss)			(1,998)	963
Ending balance, accumulated other comprehensive income	$ (1,396)	$ 1,273	$ (1,396)	$ 1,273

Derivative Financial Instrume_3

Derivative Financial Instruments - Schedule of Notional Balances and Fair Value of Derivative Positions (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Interest Rate Lock Commitments [Member]
Derivatives Fair Value [Line Items]
Outstanding Notional Balance		$ 9,438
Derivative financial instruments, assets at fair value		305
Forward Mortgage-Backed Securities Trades [Member]
Derivatives Fair Value [Line Items]
Outstanding Notional Balance		40,750
Derivative financial instruments, assets at fair value		3
Derivative financial instruments, liabilities at fair value		83
Commercial Loan Interest Rate Swaps and Caps [Member] | Loan Customer Counterparty [Member]
Derivatives Fair Value [Line Items]
Outstanding Notional Balance	$ 230,152	231,345
Derivative financial instruments, assets at fair value	14,374	4,829
Derivative financial instruments, liabilities at fair value		240
Commercial Loan Interest Rate Swaps and Caps [Member] | Financial Institution Counterparty [Member]
Derivatives Fair Value [Line Items]
Outstanding Notional Balance	230,152	231,345
Derivative financial instruments, assets at fair value		240
Derivative financial instruments, liabilities at fair value	$ 14,374	$ 4,829

Derivative Financial Instrume_4

Derivative Financial Instruments - Schedule of Weighted Average Received and Paid Interest Rates for Interest Rate Swaps Outstanding (Details) - Commercial Loan Interest Rate Swaps and Caps [Member] - Loan Customer Counterparty [Member]	Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Weighted-Average Interest Rate Received	0.0084	0.0342
Weighted-Average Interest Rate Paid	0.0286	0.0286

Derivative Financial Instrume_5

Derivative Financial Instruments - Additional Information (Details) - Interest Rate Swap - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Credit exposure	$ 14,400,000	$ 4,800,000
Cash collateral pledged	14,300,000	$ 9,300,000
Financial Institution Counterparty [Member]
Derivative [Line Items]
Credit exposure	$ 0

Derivative Financial Instrume_6

Derivative Financial Instruments - Schedule of Income (Loss) from Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Interest Rate Lock Commitments [Member]
Derivative Instruments Gain Loss [Line Items]
Derivatives not designated as hedging instruments	$ (1,417)	$ (305)
Forward Mortgage-Backed Securities Trades [Member]
Derivative Instruments Gain Loss [Line Items]
Derivatives not designated as hedging instruments	$ (461)	$ (2,398)

Acquisitions (Summary) - Additi

Acquisitions (Summary) - Additional Information (Details)	6 Months Ended
	Jun. 30, 2020
Minimum [Member]
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	10 years
Maximum [Member]
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	15 years

Acquisitions (2019 Acquisitions

Acquisitions (2019 Acquisitions) - Additional Information (Details) $ / shares in Units, $ in Thousands	Nov. 01, 2019USD ($)LocationCity$ / sharesshares	Jun. 30, 2020USD ($)	Jun. 30, 2020USD ($)shares	Dec. 31, 2019USD ($)	Mar. 31, 2020USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Business Acquisition [Line Items]
Total assets		$ 32,966,649	$ 32,966,649	$ 32,185,708
Total deposits		26,152,688	26,152,688	24,199,732
Shareholders’ equity		5,948,122	5,948,122	5,970,835	$ 5,855,574		$ 4,127,895	$ 4,109,790	$ 4,052,824
Goodwill		3,231,964	3,231,964	3,223,671					$ 1,900,845
Finite-lived intangible assets acquired				60,058
Merger-related expenses		7,474	$ 8,018
Legacy Texas [Member]
Business Acquisition [Line Items]
Total assets						$ 10,500,000
Total gross loans						9,100,000
Total deposits						6,500,000
Shareholders’ equity						$ 1,200,000
Legacy Texas [Member]
Business Acquisition [Line Items]
Business acquisition, equity interest issued or issuable, number of shares | shares	26,228,148		26,228,148
Business acquisition, closing share price | $ / shares	$ 69.02
Payments to acquire businesses in cash	$ 318,000		$ 318,018
Payments to acquire businesses in cash, cash	308,600
Payments to acquire businesses in cash, cash for taxes withheld	$ 9,400
Goodwill		1,331,119	1,331,119
Finite-lived intangible assets acquired			54,200
Merger-related expenses		$ 7,500	$ 8,000	$ 46,400
Legacy Texas [Member] | North Texas [Member]
Business Acquisition [Line Items]
Number of bank operating locations | Location	42
Number of bank operating cities | City	19

Acquisitions - Amounts Recorded

Acquisitions - Amounts Recorded on Consolidated Balance Sheet on Acquisition Date (Details) - USD ($) $ in Thousands	Nov. 01, 2019	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair value of liabilities assumed:
Goodwill		$ 3,231,964	$ 3,223,671	$ 1,900,845
Legacy Texas [Member]
Fair value of consideration paid:
Common stock issued (26,228,148 shares)		1,810,267
Payments to acquire businesses in cash	$ 318,000	318,018
Total consideration paid		2,128,285
Fair value of assets acquired:
Cash and due from banks		228,649
Securities held to maturity		472,933
Loans held for sale		60,818
Loans held for investment		6,771,080
Loans held for investment - Warehouse Purchase Program		1,693,049
Bank premises and equipment		65,514
Other real estate owned		4,876
Core deposit intangibles		60,058
Federal Home Loan Bank stock		117,826
Bank owned life insurance and other assets		235,579
Total assets acquired		9,710,382
Fair value of liabilities assumed:
Deposits		6,434,732
Other borrowings		2,078,682
Securities sold under repurchase agreements		57,670
Trust preferred securities		15,376
Subordinated notes		125,950
Other liabilities		200,806
Total liabilities assumed		8,913,216
Fair value of net assets acquired		797,166
Goodwill		1,331,119
ASC 805 [Member] | Legacy Texas [Member]
Fair value of consideration paid:
Common stock issued (26,228,148 shares)	1,810,267
Payments to acquire businesses in cash	318,018
Total consideration paid	2,128,285
Fair value of assets acquired:
Cash and due from banks	228,649
Securities held to maturity	472,933
Loans held for sale	60,818
Loans held for investment	6,771,080
Loans held for investment - Warehouse Purchase Program	1,693,049
Bank premises and equipment	67,347
Other real estate owned	4,876
Core deposit intangibles	60,058
Federal Home Loan Bank stock	117,939
Bank owned life insurance and other assets	242,592
Total assets acquired	9,719,341
Fair value of liabilities assumed:
Deposits	6,434,732
Other borrowings	2,078,682
Securities sold under repurchase agreements	57,670
Trust preferred securities	15,376
Subordinated notes	125,950
Other liabilities	201,472
Total liabilities assumed	8,913,882
Fair value of net assets acquired	805,459
Goodwill	$ 1,322,826
Measurement Period Adjustments [Member] | ASC 805 [Member] | Legacy Texas [Member]
Fair value of assets acquired:
Bank premises and equipment		(1,833)
Federal Home Loan Bank stock		(113)
Bank owned life insurance and other assets		(7,013)
Total assets acquired		(8,959)
Fair value of liabilities assumed:
Other liabilities		(666)
Total liabilities assumed		(666)
Fair value of net assets acquired		(8,293)
Goodwill		$ 8,293

Acquisitions - Amounts Record_2

Acquisitions - Amounts Recorded on Consolidated Balance Sheet on Acquisition Date (Parenthetical) (Details) - shares	Nov. 01, 2019	Jun. 30, 2020
Legacy Texas [Member]
Business Acquisition [Line Items]
Business acquisition, equity interest issued or issuable, number of shares	26,228,148	26,228,148

Acquisitions - Summary of Pro F

Acquisitions - Summary of Pro Forma Information (Details) - Legacy Texas [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Changes In Accretable Yield for PCI And Non PCI Loans [Line Items]
Net interest income	$ 270,971	$ 536,218
Net income	$ 131,508	$ 227,277
Basic earnings per share	$ 1.37	$ 2.37
Diluted earnings per share	$ 1.37	$ 2.37