Loans Acquired - Nonaccrual Acquired Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	$ 61,956	$ 34,201
Consumer
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	1,898	2,455
Consumer | Other consumer
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	1,571	2,159
Real Estate
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	27,635	20,413
Real Estate | Construction
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	2,140	1,269
Real Estate | Single family residential
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	15,648	11,939
Real Estate | Other commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	9,847	7,205
Commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	32,423	11,333
Commercial | Commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	31,240	10,049
Commercial | Agricultural
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	1,183	1,284
Loans Acquired
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	31,703	21,640
Loans Acquired | Consumer | Other consumer
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	149	140
Loans Acquired | Real Estate
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	23,676	7,884
Loans Acquired | Real Estate | Construction
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	8,221	114
Loans Acquired | Real Estate | Single family residential
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	6,482	6,603
Loans Acquired | Real Estate | Other commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	8,973	1,167
Loans Acquired | Commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	7,878	13,616
Loans Acquired | Commercial | Commercial
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	7,858	13,578
Loans Acquired | Commercial | Agricultural
Financing Receivable, Past Due [Line Items]
Loans in nonaccrual status	$ 20	$ 38