Loans - Schedule of Allowances for Loan Losses by Portfolio Segment (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Loans Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 22,377	$ 23,593	$ 23,593
Provision for loan losses	2,498	6,298	9,947
Loans charged off	(3,579)	(6,236)	(13,284)
Recoveries of loans previously charged off	958	562	2,121
Ending balance	22,254	24,217	22,377
Period-End Amount Allocated to [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	3,445	4,545	3,585
Loans collectively evaluated for impairment	18,809	19,672	18,792
Ending balance	22,254	24,217	22,377
Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	32,522	38,811	39,203
Collectively evaluated for impairment	1,737,537	1,517,016	1,579,251
Ending balance	1,770,059	1,555,827	1,618,454
Commercial, Financial and Agricultural [Member] | Loans Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,823	2,439	2,439
Provision for loan losses	1,087	1,118	711
Loans charged off	(908)	(734)	(1,759)
Recoveries of loans previously charged off	183	128	432
Ending balance	2,185	2,951	1,823
Commercial, Financial and Agricultural [Member] | Period-End Amount Allocated to [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	282	876	356
Loans collectively evaluated for impairment	1,903	2,075	1,467
Ending balance	2,185	2,951	1,823
Commercial, Financial and Agricultural [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	855	3,705	3,457
Collectively evaluated for impairment	303,733	204,719	240,916
Ending balance	304,588	208,424	244,373
Real Estate - Construction and Development [Member] | Loans Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	5,538	5,343	5,343
Provision for loan losses	(89)	1,526	1,742
Loans charged off	(222)	(1,231)	(2,020)
Recoveries of loans previously charged off	204	4	473
Ending balance	5,431	5,642	5,538
Real Estate - Construction and Development [Member] | Period-End Amount Allocated to [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	710	467	407
Loans collectively evaluated for impairment	4,721	5,175	5,131
Ending balance	5,431	5,642	5,538
Real Estate - Construction and Development [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	3,264	3,935	3,581
Collectively evaluated for impairment	146,082	130,672	142,790
Ending balance	149,346	134,607	146,371
Real Estate - Commercial and Farmland [Member] | Loans Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	8,393	9,157	9,157
Provision for loan losses	1,074	1,420	2,777
Loans charged off	(1,302)	(1,793)	(3,571)
Recoveries of loans previously charged off	152	13	30
Ending balance	8,317	8,797	8,393
Real Estate - Commercial and Farmland [Member] | Period-End Amount Allocated to [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	1,652	1,629	1,427
Loans collectively evaluated for impairment	6,665	7,168	6,966
Ending balance	8,317	8,797	8,393
Real Estate - Commercial and Farmland [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	16,865	15,842	15,240
Collectively evaluated for impairment	833,135	772,812	793,083
Ending balance	850,000	788,654	808,323
Real Estate - Residential [Member] | Loans Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	6,034	5,898	5,898
Provision for loan losses	(66)	2,340	4,463
Loans charged off	(933)	(2,107)	(5,215)
Recoveries of loans previously charged off	131	229	888
Ending balance	5,166	6,360	6,034
Real Estate - Residential [Member] | Period-End Amount Allocated to [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	801	1,573	1,395
Loans collectively evaluated for impairment	4,365	4,787	4,639
Ending balance	5,166	6,360	6,034
Real Estate - Residential [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	11,538	15,329	16,925
Collectively evaluated for impairment	411,193	342,356	349,957
Ending balance	422,731	357,685	366,882
Consumer Installment Loans and Other [Member] | Loans Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	589	756	756
Provision for loan losses	492	(106)	254
Loans charged off	(214)	(371)	(719)
Recoveries of loans previously charged off	288	188	298
Ending balance	1,155	467	589
Consumer Installment Loans and Other [Member] | Period-End Amount Allocated to [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans collectively evaluated for impairment	1,155	467	589
Ending balance	1,155	467	589
Consumer Installment Loans and Other [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Collectively evaluated for impairment	43,394	66,457	52,505
Ending balance	$ 43,394	$ 66,457	$ 52,505