Loans and Leases - Reserve for Loan and Lease Losses and Recorded Investment in Loans and Leases (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				$ 24,746				$ 29,870	$ 24,746	$ 29,870	$ 30,898
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	2,963				208				2,963	208
Ending balance: collectively evaluated for impairment	21,531				24,538				21,531	24,538
Ending balance	24,494				24,746				24,494	24,746	29,870
Provision (recovery of provision)	1,614	4,094	3,446	2,074	2,382	2,210	1,343	4,100	11,228	10,035	17,479
Loans and leases held for investment :
Ending balance: individually evaluated for impairment	58,333				45,184				58,333	45,184
Ending balance: collectively evaluated for impairment	1,483,151				1,436,678				1,483,151	1,436,678
Ending balance	1,541,484				1,481,862				1,541,484	1,481,862
Charge-offs									(13,619)	(16,735)	(19,703)
Recoveries									2,139	1,576	1,196
Balance at end of year	24,494				24,746				24,494	24,746	29,870
Commercial, Financial and Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				11,594				11,262	11,594	11,262
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	2,398				208				2,398	208
Ending balance: collectively evaluated for impairment	7,391				11,386				7,391	11,386
Ending balance	9,789				11,594				9,789	11,594
Provision (recovery of provision)									1,088	9,822
Loans and leases held for investment :
Ending balance: individually evaluated for impairment	14,105				3,322				14,105	3,322
Ending balance: collectively evaluated for impairment	408,711				465,099				408,711	465,099
Ending balance	422,816				468,421				422,816	468,421
Charge-offs									(3,213)	(9,974)
Recoveries									320	484
Balance at end of year	9,789				11,594				9,789	11,594
Real Estate-Commercial and Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				7,507				13,317	7,507	13,317
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	8,780				7,507				8,780	7,507
Ending balance	8,780				7,507				8,780	7,507
Provision (recovery of provision)									8,836	(1,341)
Loans and leases held for investment :
Ending balance: individually evaluated for impairment	41,240				40,848				41,240	40,848
Ending balance: collectively evaluated for impairment	649,606				580,524				649,606	580,524
Ending balance	690,846				621,372				690,846	621,372
Charge-offs									(8,667)	(4,803)
Recoveries									1,104	334
Balance at end of year	8,780				7,507				8,780	7,507
Real Estate-Residential Secured for Business Purpose [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				639				823	639	823
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	501								501
Ending balance: collectively evaluated for impairment	561				639				561	639
Ending balance	1,062				639				1,062	639
Provision (recovery of provision)									522	(244)
Loans and leases held for investment :
Ending balance: individually evaluated for impairment	1,774				172				1,774	172
Ending balance: collectively evaluated for impairment	35,545				35,007				35,545	35,007
Ending balance	37,319				35,179				37,319	35,179
Charge-offs									(112)
Recoveries									13	60
Balance at end of year	1,062				639				1,062	639
Real Estate-Residential and Home Equity Secured for Personal Purpose [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				980				735	980	735
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	64								64
Ending balance: collectively evaluated for impairment	1,220				980				1,220	980
Ending balance	1,284				980				1,284	980
Provision (recovery of provision)									486	394
Loans and leases held for investment :
Ending balance: individually evaluated for impairment	1,178				804				1,178	804
Ending balance: collectively evaluated for impairment	243,331				228,449				243,331	228,449
Ending balance	244,509				229,253				244,509	229,253
Charge-offs									(195)	(156)
Recoveries									13	7
Balance at end of year	1,284				980				1,284	980
Loans to Individuals [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				679				730	679	730
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	694				679				694	679
Ending balance	694				679				694	679
Provision (recovery of provision)									482	397
Loans and leases held for investment :
Ending balance: individually evaluated for impairment	36				38				36	38
Ending balance: collectively evaluated for impairment	39,964				43,742				39,964	43,742
Ending balance	40,000				43,780				40,000	43,780
Charge-offs									(641)	(578)
Recoveries									174	130
Balance at end of year	694				679				694	679
Lease Financing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				1,326				1,344	1,326	1,344
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	1,285				1,326				1,285	1,326
Ending balance	1,285				1,326				1,285	1,326
Provision (recovery of provision)									235	645
Loans and leases held for investment :
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	105,994				83,857				105,994	83,857
Ending balance	105,994				83,857				105,994	83,857
Charge-offs									(791)	(1,224)
Recoveries									515	561
Balance at end of year	1,285				1,326				1,285	1,326
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				2,021				1,659	2,021	1,659
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	1,600				2,021				1,600	2,021
Ending balance	1,600				2,021				1,600	2,021
Provision (recovery of provision)									(421)	362
Loans and leases held for investment :
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment
Ending balance
Charge-offs
Recoveries
Balance at end of year	$ 1,600				$ 2,021				$ 1,600	$ 2,021