Loans and the Allowance for Loan Losses (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Past due and nonaccrual loans
Loans and Leases Receivable, Net of Deferred Income	$ 3,881,532		$ 2,810,253
Loans and Leases Receivable, Gross	3,881,533		2,810,258
Commercial, financial, agricultural [Member]
Past due and nonaccrual loans
Loans and Leases Receivable, Net of Deferred Income	481,243		317,050
Loans and Leases Receivable, Gross	481,243		317,050
Lease financing [Member]
Past due and nonaccrual loans
Loans and Leases Receivable, Gross	76		195
Real estate - construction [Member]
Past due and nonaccrual loans
Loans and Leases Receivable, Net of Deferred Income	152,217		105,706
Loans and Leases Receivable, Gross	152,217		105,706
Real estate - 1-4 family mortgage [Member]
Past due and nonaccrual loans
Loans and Leases Receivable, Net of Deferred Income	1,192,223		903,423
Loans and Leases Receivable, Gross	1,192,223		903,423
Real estate - commercial mortgage [Member]
Past due and nonaccrual loans
Loans and Leases Receivable, Net of Deferred Income	1,960,584		1,426,643
Loans and Leases Receivable, Gross	1,960,584		1,426,643
Installment loans to individuals [Member]
Past due and nonaccrual loans
Loans and Leases Receivable, Net of Deferred Income	95,265	[1]	57,431	[1]
Loans and Leases Receivable, Gross	95,190		57,241
Unearned income [Member]
Past due and nonaccrual loans
Loans and Leases Receivable, Gross	(1)		(5)
Accruing Loans [Member]
Past due and nonaccrual loans
30-89 Days Past Due	24,178		12,530
90 Days or More Past Due	11,152		3,307
Current Loans	3,776,398		2,714,349
Total Loans, Accruing	3,811,728		2,730,186
Accruing Loans [Member] | Commercial, financial, agricultural [Member]
Past due and nonaccrual loans
30-89 Days Past Due	1,362		484
90 Days or More Past Due	272		15
Current Loans	476,874		312,943
Total Loans, Accruing	478,508		313,442
Accruing Loans [Member] | Lease financing [Member]
Past due and nonaccrual loans
30-89 Days Past Due	0		0
90 Days or More Past Due	0		0
Current Loans	76		195
Total Loans, Accruing	76		195
Accruing Loans [Member] | Real estate - construction [Member]
Past due and nonaccrual loans
30-89 Days Past Due	1		80
90 Days or More Past Due	592		0
Current Loans	149,976		103,978
Total Loans, Accruing	150,569		104,058
Accruing Loans [Member] | Real estate - 1-4 family mortgage [Member]
Past due and nonaccrual loans
30-89 Days Past Due	11,965		6,685
90 Days or More Past Due	3,436		1,992
Current Loans	1,158,038		867,053
Total Loans, Accruing	1,173,439		875,730
Accruing Loans [Member] | Real estate - commercial mortgage [Member]
Past due and nonaccrual loans
30-89 Days Past Due	10,526		5,084
90 Days or More Past Due	6,796		1,250
Current Loans	1,896,754		1,373,470
Total Loans, Accruing	1,914,076		1,379,804
Accruing Loans [Member] | Installment loans to individuals [Member]
Past due and nonaccrual loans
30-89 Days Past Due	324		197
90 Days or More Past Due	56		50
Current Loans	94,681		56,715
Total Loans, Accruing	95,061		56,962
Accruing Loans [Member] | Unearned income [Member]
Past due and nonaccrual loans
30-89 Days Past Due	0		0
90 Days or More Past Due	0		0
Current Loans	1		5
Total Loans, Accruing	1		5
Nonaccruing Loans [Member]
Past due and nonaccrual loans
30-89 Days Past Due	5,570		1,796
90 Days or More Past Due	42,711		56,758
Current Loans	21,523		21,513
Total Loans, Nonaccuring	69,804		80,067
Nonaccruing Loans [Member] | Commercial, financial, agricultural [Member]
Past due and nonaccrual loans
30-89 Days Past Due	0		215
90 Days or More Past Due	1,922		3,131
Current Loans	813		262
Total Loans, Nonaccuring	2,735		3,608
Nonaccruing Loans [Member] | Lease financing [Member]
Past due and nonaccrual loans
30-89 Days Past Due	0		0
90 Days or More Past Due	0		0
Current Loans	0		0
Total Loans, Nonaccuring	0		0
Nonaccruing Loans [Member] | Real estate - construction [Member]
Past due and nonaccrual loans
30-89 Days Past Due	0		0
90 Days or More Past Due	1,648		1,648
Current Loans	0		0
Total Loans, Nonaccuring	1,648		1,648
Nonaccruing Loans [Member] | Real estate - 1-4 family mortgage [Member]
Past due and nonaccrual loans
30-89 Days Past Due	2,276		1,249
90 Days or More Past Due	5,788		13,417
Current Loans	10,720		13,027
Total Loans, Nonaccuring	18,784		27,693
Nonaccruing Loans [Member] | Real estate - commercial mortgage [Member]
Past due and nonaccrual loans
30-89 Days Past Due	3,294		325
90 Days or More Past Due	33,224		38,297
Current Loans	9,990		8,217
Total Loans, Nonaccuring	46,508		46,839
Nonaccruing Loans [Member] | Installment loans to individuals [Member]
Past due and nonaccrual loans
30-89 Days Past Due	0		7
90 Days or More Past Due	129		265
Current Loans	0		7
Total Loans, Nonaccuring	129		279
Nonaccruing Loans [Member] | Unearned income [Member]
Past due and nonaccrual loans
30-89 Days Past Due	0		0
90 Days or More Past Due	0		0
Current Loans	0		0
Total Loans, Nonaccuring	$ 0		$ 0

[1] Includes lease financing receivables.