Schedule of Loans by Class (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Loans and Leases Receivable [Line Items]
Loans held for investment	$ 5,340,189	$ 5,193,321
Mortgage loans held for sale	73,053	52,875
Total loans	5,413,242	5,246,196
Commercial real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	1,816,813	1,793,258
Land acquisition & development construction real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	218,650	224,066
Residential construction real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	113,944	111,763
Commercial construction real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	117,643	94,890
Total construction loans
Loans and Leases Receivable [Line Items]
Loans held for investment	450,237	430,719
Residential real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	1,030,593	1,032,851
Agricultural real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	166,872	156,234
Total real estate loans
Loans and Leases Receivable [Line Items]
Loans held for investment	3,464,515	3,413,062
Indirect consumer
Loans and Leases Receivable [Line Items]
Loans held for investment	687,768	622,529
Other consumer
Loans and Leases Receivable [Line Items]
Loans held for investment	153,185	153,717
Credit card consumer
Loans and Leases Receivable [Line Items]
Loans held for investment	66,221	68,107
Total consumer loans
Loans and Leases Receivable [Line Items]
Loans held for investment	907,174	844,353
Commercial
Loans and Leases Receivable [Line Items]
Loans held for investment	824,962	792,416
Agricultural
Loans and Leases Receivable [Line Items]
Loans held for investment	139,892	142,151
Other, including overdrafts
Loans and Leases Receivable [Line Items]
Loans held for investment	$ 3,646	$ 1,339