Loans and the Allowance for Loan Losses (Details 10) - USD ($) $ in Thousands		3 Months Ended												12 Months Ended
		Dec. 31, 2015		Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Rollforward of the allowance for loan losses
Beginning balance						$ 42,289						$ 47,665		$ 42,289		$ 47,665		$ 44,347
Charge-offs														(6,776)		(13,859)		(9,551)
Recoveries														2,174		2,316		2,519
Net charge-offs														(4,602)		(11,543)		(7,032)
Provision for loan losses														3,913		10,917		11,738
Benefit attributable to FDIC loss-share agreements														(872)		(6,278)		(2,361)
Recoveries payable to FDIC														1,709		1,528		973
Provision for loan losses charged to operations		$ 1,750		$ 750	$ 1,175	1,075		$ 1,050		$ 2,217	$ 1,450	1,450		4,750		6,167		10,350
Ending balance		42,437						42,289						42,437		42,289		47,665
Period-End Amount Allocated to:
Individually evaluated for impairment																			$ 7,600		$ 10,256		$ 14,650
Collectively evaluated for impairment																			33,131		30,308		32,371
Acquired with deteriorated credit quality		42,437				42,289		42,289				47,665		42,289		47,665		44,347	42,437		42,289		47,665
Commercial, financial, agricultural
Rollforward of the allowance for loan losses
Beginning balance						3,305						3,090		3,305		3,090		3,307
Charge-offs														(943)		(1,516)		(1,184)
Recoveries														361		455		356
Net charge-offs														(582)		(1,061)		(828)
Provision for loan losses														1,489		1,297		982
Benefit attributable to FDIC loss-share agreements														(64)		(204)		(403)
Recoveries payable to FDIC														38		183		32
Provision for loan losses charged to operations														1,463		1,276		611
Ending balance		4,186						3,305						4,186		3,305		3,090
Period-End Amount Allocated to:
Individually evaluated for impairment																			6		5		260
Collectively evaluated for impairment																			3,827		3,020		2,624
Acquired with deteriorated credit quality		4,186				3,305		3,305				3,090		3,305		3,090		3,307	4,186		3,305		3,090
Real estate – construction
Rollforward of the allowance for loan losses
Beginning balance						1,415						1,091		1,415		1,091		711
Charge-offs														(26)		0		0
Recoveries														26		33		75
Net charge-offs														0		33		75
Provision for loan losses														435		290		304
Benefit attributable to FDIC loss-share agreements														0		0		0
Recoveries payable to FDIC														2		1		1
Provision for loan losses charged to operations														437		291		305
Ending balance		1,852						1,415						1,852		1,415		1,091
Period-End Amount Allocated to:
Individually evaluated for impairment																			20		0		0
Collectively evaluated for impairment																			1,832		1,415		1,091
Acquired with deteriorated credit quality		1,852				1,415		1,415				1,091		1,415		1,091		711	1,852		1,415		1,091
Real estate – 1-4 family mortgage
Rollforward of the allowance for loan losses
Beginning balance						13,549						18,629		13,549		18,629		18,347
Charge-offs														(2,173)		(5,662)		(3,093)
Recoveries														1,064		1,325		1,044
Net charge-offs														(1,109)		(4,337)		(2,049)
Provision for loan losses														650		(452)		2,496
Benefit attributable to FDIC loss-share agreements														(91)		(816)		(1,039)
Recoveries payable to FDIC														909		525		874
Provision for loan losses charged to operations														1,468		(743)		2,331
Ending balance		13,908						13,549						13,908		13,549		18,629
Period-End Amount Allocated to:
Individually evaluated for impairment																			4,475		4,786		7,353
Collectively evaluated for impairment																			9,177		8,483		11,257
Acquired with deteriorated credit quality		13,908				13,549		13,549				18,629		13,549		18,629		18,347	13,908		13,549		18,629
Real estate – commercial mortgage
Rollforward of the allowance for loan losses
Beginning balance						22,759						23,688		22,759		23,688		21,416
Charge-offs														(2,613)		(6,186)		(4,782)
Recoveries														614		436		980
Net charge-offs														(1,999)		(5,750)		(3,802)
Provision for loan losses														312		9,260		6,927
Benefit attributable to FDIC loss-share agreements														(717)		(5,258)		(919)
Recoveries payable to FDIC														756		819		66
Provision for loan losses charged to operations														351		4,821		6,074
Ending balance		21,111						22,759						21,111		22,759		23,688
Period-End Amount Allocated to:
Individually evaluated for impairment																			3,099		5,465		7,036
Collectively evaluated for impairment																			16,916		16,130		16,369
Acquired with deteriorated credit quality		21,111				22,759		22,759				23,688		22,759		23,688		21,416	21,111		22,759		23,688
Installment loans to individuals
Rollforward of the allowance for loan losses
Beginning balance						1,261	[1]					1,167	[1]	1,261	[1]	1,167	[1]	566
Charge-offs	[1]													(1,021)		(495)		(492)
Recoveries	[1]													109		67		64
Net charge-offs	[1]													(912)		(428)		(428)
Provision for loan losses	[1]													1,027		522		1,029
Benefit attributable to FDIC loss-share agreements	[1]													0		0		0
Recoveries payable to FDIC	[1]													4		0		0
Provision for loan losses charged to operations	[1]													1,031		522		1,029
Ending balance	[1]	1,380						1,261						1,380		1,261		1,167
Period-End Amount Allocated to:
Individually evaluated for impairment	[1]																		0		0		1
Collectively evaluated for impairment	[1]																		1,379		1,260		1,030
Acquired with deteriorated credit quality		1,380	[1]			1,261	[1]	1,261	[1]			1,167	[1]	1,261	[1]	1,167	[1]	566	1,380	[1]	1,261	[1]	1,167	[1]
Receivables Acquired with Deteriorated Credit Quality
Rollforward of the allowance for loan losses
Beginning balance						1,725						644		1,725		644
Ending balance		1,706						1,725						1,706		1,725		644
Period-End Amount Allocated to:
Acquired with deteriorated credit quality		1,706				1,725		1,725				644		1,725		644		644	1,706		1,725		644
Receivables Acquired with Deteriorated Credit Quality | Commercial, financial, agricultural
Rollforward of the allowance for loan losses
Beginning balance						280						206		280		206
Ending balance		353						280						353		280		206
Period-End Amount Allocated to:
Acquired with deteriorated credit quality		353				280		280				206		280		206		206	353		280		206
Receivables Acquired with Deteriorated Credit Quality | Real estate – construction
Rollforward of the allowance for loan losses
Beginning balance						0						0		0		0
Ending balance		0						0						0		0		0
Period-End Amount Allocated to:
Acquired with deteriorated credit quality		0				0		0				0		0		0		0	0		0		0
Receivables Acquired with Deteriorated Credit Quality | Real estate – 1-4 family mortgage
Rollforward of the allowance for loan losses
Beginning balance						280						19		280		19
Ending balance		256						280						256		280		19
Period-End Amount Allocated to:
Acquired with deteriorated credit quality		256				280		280				19		280		19		19	256		280		19
Receivables Acquired with Deteriorated Credit Quality | Real estate – commercial mortgage
Rollforward of the allowance for loan losses
Beginning balance						1,164						283		1,164		283
Ending balance		1,096						1,164						1,096		1,164		283
Period-End Amount Allocated to:
Acquired with deteriorated credit quality		1,096				1,164		1,164				283		1,164		283		283	1,096		1,164		283
Receivables Acquired with Deteriorated Credit Quality | Installment loans to individuals
Rollforward of the allowance for loan losses
Beginning balance						1						136		1		136
Ending balance		1						1						1		1		136
Period-End Amount Allocated to:
Acquired with deteriorated credit quality		$ 1				$ 1		$ 1				$ 136		$ 1		$ 136		$ 136	$ 1		$ 1		$ 136

[1] Includes lease financing receivables.