Loans Acquired - Summary of Acquired Loans, Excluding Loans Covered by Loss Share (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 14,425,260	$ 11,723,171
Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	14,112,831	11,523,787
Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	102,618	80,394
Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	209,421	118,407
Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	173	583
Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	217	0
Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,795,184	3,292,783
Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,653,295	3,187,083
Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	43,602	51,255
Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	97,900	54,097
Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	170	348
Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	217	0
Consumer | Other consumer | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	57,748	15,658
Consumer | Other consumer | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	57,318	15,380
Consumer | Other consumer | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Consumer | Other consumer | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	430	278
Consumer | Other consumer | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Consumer | Other consumer | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Real Estate | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,999,658	2,844,472
Real Estate | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,900,116	2,768,761
Real Estate | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	42,074	38,839
Real Estate | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	57,304	36,524
Real Estate | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	127	348
Real Estate | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	37	0
Real Estate | Construction and development | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	475,967	429,605
Real Estate | Construction and development | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	474,750	393,122
Real Estate | Construction and development | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	21	27,621
Real Estate | Construction and development | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,159	8,862
Real Estate | Construction and development | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Real Estate | Construction and development | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	37	0
Real Estate | Single family residential | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	997,444	566,188
Real Estate | Single family residential | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	978,681	553,460
Real Estate | Single family residential | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,181	2,081
Real Estate | Single family residential | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	17,455	10,299
Real Estate | Single family residential | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	127	348
Real Estate | Single family residential | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Real Estate | Other commercial | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,526,247	1,848,679
Real Estate | Other commercial | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,446,685	1,822,179
Real Estate | Other commercial | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	40,872	9,137
Real Estate | Other commercial | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	38,690	17,363
Real Estate | Other commercial | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Real Estate | Other commercial | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	737,778	432,653
Commercial | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	695,861	402,942
Commercial | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,528	12,416
Commercial | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	40,166	17,295
Commercial | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	43	0
Commercial | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	180	0
Commercial | Commercial | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	585,720	430,914
Commercial | Commercial | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	548,928	401,300
Commercial | Commercial | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,528	12,416
Commercial | Commercial | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	35,041	17,198
Commercial | Commercial | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	43	0
Commercial | Commercial | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	180	0
Commercial | Agricultural | Loans acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	152,058	1,739
Commercial | Agricultural | Loans acquired | Risk Rate 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	146,933	1,642
Commercial | Agricultural | Loans acquired | Risk Rate 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial | Agricultural | Loans acquired | Risk Rate 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	5,125	97
Commercial | Agricultural | Loans acquired | Risk Rate 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial | Agricultural | Loans acquired | Risk Rate 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 0	$ 0