Loans and Allowance for Loan Losses - Nonaccrual Loans, Excluding Loans Acquired, Segregated by Class of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	$ 70,836	$ 34,201
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	1,760	2,455
Consumer | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	382	296
Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	1,378	2,159
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	32,001	20,413
Real Estate | Construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	4,538	1,269
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	18,102	11,939
Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	9,361	7,205
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	37,075	11,333
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	36,575	10,049
Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in nonaccrual status	$ 500	$ 1,284