Schedule of Loans by Class (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Loans and Leases Receivable [Line Items]
Loans held for investment	$ 5,462,936	$ 5,193,321
Mortgage loans held for sale	67,979	52,875
Total loans	5,530,915	5,246,196
Commercial real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	1,843,120	1,793,258
Land acquisition & development construction real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	212,680	224,066
Residential construction real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	137,014	111,763
Commercial construction real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	128,154	94,890
Total construction loans
Loans and Leases Receivable [Line Items]
Loans held for investment	477,848	430,719
Residential real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	1,047,150	1,032,851
Agricultural real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	172,949	156,234
Total real estate loans
Loans and Leases Receivable [Line Items]
Loans held for investment	3,541,067	3,413,062
Indirect consumer
Loans and Leases Receivable [Line Items]
Loans held for investment	731,901	622,529
Other consumer
Loans and Leases Receivable [Line Items]
Loans held for investment	153,624	153,717
Credit card consumer
Loans and Leases Receivable [Line Items]
Loans held for investment	66,860	68,107
Total consumer loans
Loans and Leases Receivable [Line Items]
Loans held for investment	952,385	844,353
Commercial
Loans and Leases Receivable [Line Items]
Loans held for investment	814,392	792,416
Agricultural
Loans and Leases Receivable [Line Items]
Loans held for investment	152,800	142,151
Other, including overdrafts
Loans and Leases Receivable [Line Items]
Loans held for investment	$ 2,292	$ 1,339