Loans and the Allowance for Loan Losses (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Summary of loans
Gross loans	$ 3,881,533		$ 2,810,258
Unearned income	(1)		(5)
Loans, net of unearned income	3,881,532		2,810,253
Allowance for loan losses	(46,250)		(44,347)
Loans, net	3,835,282		2,765,906
Commercial, financial, agricultural [Member]
Summary of loans
Gross loans	481,243		317,050
Loans, net of unearned income	481,243		317,050
Lease financing [Member]
Summary of loans
Gross loans	76		195
Real estate - construction [Member]
Summary of loans
Gross loans	152,217		105,706
Loans, net of unearned income	152,217		105,706
Real estate - 1-4 family mortgage [Member]
Summary of loans
Gross loans	1,192,223		903,423
Loans, net of unearned income	1,192,223		903,423
Real estate - commercial mortgage [Member]
Summary of loans
Gross loans	1,960,584		1,426,643
Loans, net of unearned income	1,960,584		1,426,643
Installment loans to individuals [Member]
Summary of loans
Gross loans	95,190		57,241
Loans, net of unearned income	$ 95,265	[1]	$ 57,431	[1]

[1] Includes lease financing receivables.