Loans - Contractual Aging of Recorded Investment in Past Due Loans (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing 30-59 Days Past Due	$ 2,047,000	$ 2,168,000
Accruing 60-89 Days Past Due	1,281,000	1,382,000
Accruing Greater Than 90 Days	160,000	1,000
Nonaccrual	27,672,000	40,955,000	28,526,000
Current	1,273,047,000	1,181,575,000
Total Financing Receivables	1,304,207,000	1,226,081,000
Construction and Land Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing 30-59 Days Past Due	3,000	7,000
Accruing 60-89 Days Past Due	0	0
Accruing Greater Than 90 Days	0	0
Nonaccrual	1,302,000	1,342,000
Current	66,145,000	59,387,000
Total Financing Receivables	67,450,000	60,736,000
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing 30-59 Days Past Due	684,000	832,000
Accruing 60-89 Days Past Due	345,000	5,000
Accruing Greater Than 90 Days	0	0
Nonaccrual	5,111,000	17,234,000
Current	514,242,000	468,757,000
Total Financing Receivables	520,382,000	486,828,000
Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing 30-59 Days Past Due	974,000	1,179,000
Accruing 60-89 Days Past Due	909,000	1,377,000
Accruing Greater Than 90 Days	160,000	1,000
Nonaccrual	20,705,000	22,099,000
Current	569,998,000	544,675,000
Total Financing Receivables	592,746,000	569,331,000
Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing 30-59 Days Past Due	0	0
Accruing 60-89 Days Past Due	0	0
Accruing Greater Than 90 Days	0	0
Nonaccrual	0	0
Current	280,000	353,000
Total Financing Receivables	280,000	353,000
Commercial and Financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing 30-59 Days Past Due	353,000	41,000
Accruing 60-89 Days Past Due	0	0
Accruing Greater Than 90 Days	0	0
Nonaccrual	13,000	0
Current	78,270,000	61,862,000
Total Financing Receivables	78,636,000	61,903,000
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing 30-59 Days Past Due	33,000	109,000
Accruing 60-89 Days Past Due	27,000	0
Accruing Greater Than 90 Days	0	0
Nonaccrual	541,000	280,000
Current	44,112,000	46,541,000
Total Financing Receivables	$ 44,713,000	$ 46,930,000