Property and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 6,080,000	$ 4,264,000	$ 3,483,000
Impairment charge			$ 800,000