Loans and the Allowance for Loan Losses (Details 5) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Loan portfolio by risk-rating grades
Total	$ 3,066,005	$ 2,092,260
Pass
Loan portfolio by risk-rating grades
Total	2,982,255	2,002,478
Watch
Loan portfolio by risk-rating grades
Total	45,868	43,298
Substandard
Loan portfolio by risk-rating grades
Total	37,882	46,484
Commercial, financial, agricultural
Loan portfolio by risk-rating grades
Total	475,417	344,704
Commercial, financial, agricultural | Pass
Loan portfolio by risk-rating grades
Total	465,185	337,998
Commercial, financial, agricultural | Watch
Loan portfolio by risk-rating grades
Total	8,498	5,255
Commercial, financial, agricultural | Substandard
Loan portfolio by risk-rating grades
Total	1,734	1,451
Real estate – construction
Loan portfolio by risk-rating grades
Total	273,881	151,538
Real estate – construction | Pass
Loan portfolio by risk-rating grades
Total	273,398	150,683
Real estate – construction | Watch
Loan portfolio by risk-rating grades
Total	483	855
Real estate – construction | Substandard
Loan portfolio by risk-rating grades
Total	0	0
Real estate – 1-4 family mortgage
Loan portfolio by risk-rating grades
Total	300,441	140,166
Real estate – 1-4 family mortgage | Pass
Loan portfolio by risk-rating grades
Total	275,269	122,608
Real estate – 1-4 family mortgage | Watch
Loan portfolio by risk-rating grades
Total	9,712	6,079
Real estate – 1-4 family mortgage | Substandard
Loan portfolio by risk-rating grades
Total	15,460	11,479
Real estate – commercial mortgage
Loan portfolio by risk-rating grades
Total	2,016,210	1,454,450
Real estate – commercial mortgage | Pass
Loan portfolio by risk-rating grades
Total	1,968,352	1,389,787
Real estate – commercial mortgage | Watch
Loan portfolio by risk-rating grades
Total	27,175	31,109
Real estate – commercial mortgage | Substandard
Loan portfolio by risk-rating grades
Total	20,683	33,554
Installment loans to individuals
Loan portfolio by risk-rating grades
Total	56	1,402
Installment loans to individuals | Pass
Loan portfolio by risk-rating grades
Total	51	1,402
Installment loans to individuals | Watch
Loan portfolio by risk-rating grades
Total	0	0
Installment loans to individuals | Substandard
Loan portfolio by risk-rating grades
Total	$ 5	$ 0