Long-Term Debt and Line of Credit - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Line of Credit Facility [Line Items]
Interest paid relating to debt	$ 62,000	$ 89,000	$ 102,000
Expiration date	Jun. 13, 2013
Bank Of America Libor Rate
Line of Credit Facility [Line Items]
Line of credit facility remaining borrowing capacity	$ 5,000,000
Debt instrument variable interest rate	LIBOR rate plus 1.75%, which was 1.96