Stock Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense related to stock options	$ 59,000	$ 58,000	$ 238,000	$ 253,000
Stock based compensation expense related to amortization of non-vested stock	$ 597,000	$ 356,000	$ 1,794,000	$ 1,026,000
Stock options exercised by employees	31,435	4,500	77,620	25,800
Number of Shares of non-vested stock that vested	13,334	13,335	49,807	52,744