Allowance for Loan Losses (Details 1) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Rollforward of the allowance for loan losses
Beginning balance				$ 42,737				$ 42,437	$ 42,737	$ 42,437	$ 42,289
Charge-offs									(7,008)	(9,471)	(6,776)
Recoveries									2,932	2,241	2,174
Net charge-offs									(4,076)	(7,230)	(4,602)
Provision for loan losses										6,604	3,913
Benefit attributable to FDIC loss share agreements										(265)	(872)
Recoveries payable to FDIC										1,191	1,709
Provision for loan losses charged to operations	$ 2,150	$ 2,150	$ 1,750	1,500	$ 1,650	$ 2,650	$ 1,430	1,800	7,550	7,530	4,750
Ending balance	46,211				42,737				46,211	42,737	42,437
Period-End Amount Allocated to:
Individually evaluated for impairment												$ 2,674	$ 4,141	$ 7,600
Collectively evaluated for impairment												41,760	35,776	33,131
Acquired with deteriorated credit quality	46,211			42,737	42,737			42,437	42,737	42,437	42,289	46,211	42,737	42,437
Receivables Acquired with Deteriorated Credit Quality
Rollforward of the allowance for loan losses
Beginning balance				2,820				1,706	2,820	1,706
Ending balance	1,777				2,820				1,777	2,820	1,706
Period-End Amount Allocated to:
Acquired with deteriorated credit quality	1,777			2,820	2,820			1,706	2,820	1,706	1,706	1,777	2,820	1,706
Commercial, financial, agricultural
Rollforward of the allowance for loan losses
Beginning balance				5,486				4,186	5,486	4,186	3,305
Charge-offs									(2,874)	(2,725)	(943)
Recoveries									422	331	361
Net charge-offs									(2,452)	(2,394)	(582)
Provision for loan losses										3,716	1,489
Benefit attributable to FDIC loss share agreements										(61)	(64)
Recoveries payable to FDIC										39	38
Provision for loan losses charged to operations									2,508	3,694	1,463
Ending balance	5,542				5,486				5,542	5,486	4,186
Period-End Amount Allocated to:
Individually evaluated for impairment												190	446	6
Collectively evaluated for impairment												5,040	4,668	3,827
Acquired with deteriorated credit quality	5,542			5,486	5,486			4,186	5,486	4,186	3,305	5,542	5,486	4,186
Commercial, financial, agricultural | Receivables Acquired with Deteriorated Credit Quality
Rollforward of the allowance for loan losses
Beginning balance				372				353	372	353
Ending balance	312				372				312	372	353
Period-End Amount Allocated to:
Acquired with deteriorated credit quality	312			372	372			353	372	353	353	312	372	353
Real estate – construction
Rollforward of the allowance for loan losses
Beginning balance				2,380				1,852	2,380	1,852	1,415
Charge-offs									0	0	(26)
Recoveries									105	47	26
Net charge-offs									105	47	0
Provision for loan losses										364	435
Benefit attributable to FDIC loss share agreements										0	0
Recoveries payable to FDIC										117	2
Provision for loan losses charged to operations									943	481	437
Ending balance	3,428				2,380				3,428	2,380	1,852
Period-End Amount Allocated to:
Individually evaluated for impairment												4	1	20
Collectively evaluated for impairment												3,424	2,379	1,832
Acquired with deteriorated credit quality	3,428			2,380	2,380			1,852	2,380	1,852	1,415	3,428	2,380	1,852
Real estate – construction | Receivables Acquired with Deteriorated Credit Quality
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
Real estate – 1-4 family mortgage
Rollforward of the allowance for loan losses
Beginning balance				14,294				13,908	14,294	13,908	13,549
Charge-offs									(1,713)	(3,906)	(2,173)
Recoveries									733	997	1,064
Net charge-offs									(980)	(2,909)	(1,109)
Provision for loan losses										2,616	650
Benefit attributable to FDIC loss share agreements										(115)	(91)
Recoveries payable to FDIC										794	909
Provision for loan losses charged to operations									(1,305)	3,295	1,468
Ending balance	12,009				14,294				12,009	14,294	13,908
Period-End Amount Allocated to:
Individually evaluated for impairment												606	1,134	4,475
Collectively evaluated for impairment												10,831	12,319	9,177
Acquired with deteriorated credit quality	12,009			14,294	14,294			13,908	14,294	13,908	13,549	12,009	14,294	13,908
Real estate – 1-4 family mortgage | Receivables Acquired with Deteriorated Credit Quality
Rollforward of the allowance for loan losses
Beginning balance				841				256	841	256
Ending balance	572				841				572	841	256
Period-End Amount Allocated to:
Acquired with deteriorated credit quality	572			841	841			256	841	256	256	572	841	256
Real estate – commercial mortgage
Rollforward of the allowance for loan losses
Beginning balance				19,059				21,111	19,059	21,111	22,759
Charge-offs									(1,791)	(2,123)	(2,613)
Recoveries									1,565	757	614
Net charge-offs									(226)	(1,366)	(1,999)
Provision for loan losses										(879)	312
Benefit attributable to FDIC loss share agreements										(48)	(717)
Recoveries payable to FDIC										241	756
Provision for loan losses charged to operations									4,551	(686)	351
Ending balance	23,384				19,059				23,384	19,059	21,111
Period-End Amount Allocated to:
Individually evaluated for impairment												1,867	2,445	3,099
Collectively evaluated for impairment												20,625	15,008	16,916
Acquired with deteriorated credit quality	23,384			19,059	19,059			21,111	19,059	21,111	22,759	23,384	19,059	21,111
Real estate – commercial mortgage | Receivables Acquired with Deteriorated Credit Quality
Rollforward of the allowance for loan losses
Beginning balance				1,606				1,096	1,606	1,096
Ending balance	892				1,606				892	1,606	1,096
Period-End Amount Allocated to:
Acquired with deteriorated credit quality	892			1,606	1,606			1,096	1,606	1,096	1,096	892	1,606	1,096
Installment and Other
Rollforward of the allowance for loan losses
Beginning balance				1,518				1,380	1,518	1,380	1,261
Charge-offs									(630)	(717)	(1,021)
Recoveries									107	109	109
Net charge-offs									(523)	(608)	(912)
Provision for loan losses										787	1,027
Benefit attributable to FDIC loss share agreements										(41)	0
Recoveries payable to FDIC										0	4
Provision for loan losses charged to operations									853	746	1,031
Ending balance	1,848				1,518				1,848	1,518	1,380
Period-End Amount Allocated to:
Individually evaluated for impairment												7	115	0
Collectively evaluated for impairment												1,840	1,402	1,379
Acquired with deteriorated credit quality	1,848			1,518	1,518			1,380	1,518	1,380	1,261	1,848	1,518	1,380
Installment and Other | Receivables Acquired with Deteriorated Credit Quality
Rollforward of the allowance for loan losses
Beginning balance				1				1	1	1
Ending balance	1				1				1	1	1
Period-End Amount Allocated to:
Acquired with deteriorated credit quality	$ 1			$ 1	$ 1			$ 1	$ 1	$ 1	$ 1	$ 1	$ 1	$ 1