Loans and the Allowance for Loan Losses (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Summary of loans
Gross loans	$ 3,957,626		$ 3,881,019
Unearned income	(187)		(1)
Loans, net of unearned income	3,957,439		3,881,018
Allowance for loan losses	(44,569)		(47,665)
Loans, net	3,912,870		3,833,353
Commercial, financial, agricultural
Summary of loans
Gross loans	450,559		468,963
Loans, net of unearned income	450,559		468,963
Lease financing
Summary of loans
Gross loans	5,564		53
Real estate – construction
Summary of loans
Gross loans	197,066		161,436
Loans, net of unearned income	197,066		161,436
Real estate – 1-4 family mortgage
Summary of loans
Gross loans	1,221,579		1,208,233
Loans, net of unearned income	1,221,579		1,208,233
Real estate – commercial mortgage
Summary of loans
Gross loans	1,991,052		1,950,572
Loans, net of unearned income	1,991,052		1,950,572
Installment loans to individuals
Summary of loans
Gross loans	91,806		91,762
Loans, net of unearned income	$ 97,183	[1]	$ 91,814	[1]

[1] Includes lease financing receivables.