Schedule of Loans by Class (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Loans and Leases Receivable [Line Items]
Loans held for investment	$ 7,525,590	$ 5,416,750
Mortgage loans held for sale	30,383	61,794
Total loans	7,555,973	5,478,544
Commercial real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	2,816,526	1,834,445
Land acquisition & development construction real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	339,884	208,512
Residential construction real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	219,756	147,896
Commercial construction real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	121,605	125,589
Total construction loans
Loans and Leases Receivable [Line Items]
Loans held for investment	681,245	481,997
Residential real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	1,466,014	1,027,393
Agricultural real estate
Loans and Leases Receivable [Line Items]
Loans held for investment	163,175	170,248
Total real estate loans
Loans and Leases Receivable [Line Items]
Loans held for investment	5,126,960	3,514,083
Indirect consumer
Loans and Leases Receivable [Line Items]
Loans held for investment	779,026	752,409
Other consumer
Loans and Leases Receivable [Line Items]
Loans held for investment	175,737	148,087
Credit card consumer
Loans and Leases Receivable [Line Items]
Loans held for investment	75,631	69,770
Total consumer loans
Loans and Leases Receivable [Line Items]
Loans held for investment	1,030,394	970,266
Commercial
Loans and Leases Receivable [Line Items]
Loans held for investment	1,210,869	797,942
Agricultural
Loans and Leases Receivable [Line Items]
Loans held for investment	149,129	132,858
Other, including overdrafts
Loans and Leases Receivable [Line Items]
Loans held for investment	$ 8,238	$ 1,601