Loans and the Allowance for Loan Losses (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Past due and nonaccrual loans
Unearned income	$ (2)		$ (5)
Total Loans, Net	2,884,511		2,810,253
Loans and Leases Receivable, Gross	2,884,513		2,810,258
Commercial, financial, agricultural [Member]
Past due and nonaccrual loans
Total Loans, Net	318,001		317,050
Loans and Leases Receivable, Gross	318,001		317,050
Lease financing [Member]
Past due and nonaccrual loans
Loans and Leases Receivable, Gross	105		195
Real estate - construction [Member]
Past due and nonaccrual loans
Total Loans, Net	118,987		105,706
Loans and Leases Receivable, Gross	118,987		105,706
Real estate - 1-4 family mortgage [Member]
Past due and nonaccrual loans
Total Loans, Net	920,293		903,423
Loans and Leases Receivable, Gross	920,293		903,423
Real estate - commercial mortgage [Member]
Past due and nonaccrual loans
Total Loans, Net	1,464,522		1,426,643
Loans and Leases Receivable, Gross	1,464,522		1,426,643
Installment loans to individuals [Member]
Past due and nonaccrual loans
Total Loans, Net	62,708	[1]	57,431	[1]
Loans and Leases Receivable, Gross	62,605		57,241
Unearned income [Member]
Past due and nonaccrual loans
Loans and Leases Receivable, Gross	(2)		(5)
Accruing Loans [Member]
Past due and nonaccrual loans
30-89 Days Past Due	9,250		12,530
90 Days or More Past Due	2,109		3,307
Current Loans	2,805,317		2,714,349
Total Loans, Accruing	2,816,676		2,730,186
Accruing Loans [Member] | Commercial, financial, agricultural [Member]
Past due and nonaccrual loans
30-89 Days Past Due	405		484
90 Days or More Past Due	0		15
Current Loans	313,942		312,943
Total Loans, Accruing	314,347		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	105		195
Total Loans, Accruing	105		195
Accruing Loans [Member] | Real estate - construction [Member]
Past due and nonaccrual loans
30-89 Days Past Due	0		80
90 Days or More Past Due	0		0
Current Loans	117,339		103,978
Total Loans, Accruing	117,339		104,058
Accruing Loans [Member] | Real estate - 1-4 family mortgage [Member]
Past due and nonaccrual loans
30-89 Days Past Due	6,497		6,685
90 Days or More Past Due	943		1,992
Current Loans	891,322		867,053
Total Loans, Accruing	898,762		875,730
Accruing Loans [Member] | Real estate - commercial mortgage [Member]
Past due and nonaccrual loans
30-89 Days Past Due	2,068		5,084
90 Days or More Past Due	1,075		1,250
Current Loans	1,420,485		1,373,470
Total Loans, Accruing	1,423,628		1,379,804
Accruing Loans [Member] | Installment loans to individuals [Member]
Past due and nonaccrual loans
30-89 Days Past Due	280		197
90 Days or More Past Due	91		50
Current Loans	62,126		56,715
Total Loans, Accruing	62,497		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
Unearned income, Current Loans	(2)		(5)
Unearned income	(2)		(5)
Nonaccruing Loans [Member]
Past due and nonaccrual loans
30-89 Days Past Due	2,439		1,796
90 Days or More Past Due	45,555		56,758
Current Loans	19,841		21,513
Total Loans, Nonaccuring	67,835		80,067
Nonaccruing Loans [Member] | Commercial, financial, agricultural [Member]
Past due and nonaccrual loans
30-89 Days Past Due	390		215
90 Days or More Past Due	3,094		3,131
Current Loans	170		262
Total Loans, Nonaccuring	3,654		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	1,827		1,249
90 Days or More Past Due	8,184		13,417
Current Loans	11,520		13,027
Total Loans, Nonaccuring	21,531		27,693
Nonaccruing Loans [Member] | Real estate - commercial mortgage [Member]
Past due and nonaccrual loans
30-89 Days Past Due	222		325
90 Days or More Past Due	32,521		38,297
Current Loans	8,151		8,217
Total Loans, Nonaccuring	40,894		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	108		265
Current Loans	0		7
Total Loans, Nonaccuring	108		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.