Loans Acquired - Nonaccrual Acquired Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	$ 72,721	$ 34,201
Consumer
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	2,155	2,455
Consumer | Other consumer
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	1,634	2,159
Real Estate
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	34,981	20,413
Real Estate | Construction
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	1,805	1,269
Real Estate | Single family residential
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	16,191	11,939
Real Estate | Other commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	16,985	7,205
Commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	35,585	11,333
Commercial | Commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	35,018	10,049
Commercial | Agricultural
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	567	1,284
Loans Acquired
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	7,299	21,640
Loans Acquired | Consumer | Other consumer
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	71	140
Loans Acquired | Real Estate
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	5,569	7,884
Loans Acquired | Real Estate | Construction
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	48	114
Loans Acquired | Real Estate | Single family residential
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	4,492	6,603
Loans Acquired | Real Estate | Other commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	1,029	1,167
Loans Acquired | Commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	1,659	13,616
Loans Acquired | Commercial | Commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	1,636	13,578
Loans Acquired | Commercial | Agricultural
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	$ 23	$ 38