Notes Receivable from Stockholders - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended		12 Months Ended
	Mar. 31, 2011	Nov. 30, 2008	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Financing Receivables [Line Items]
Promissory note receivable from stockholders		$ 1,500		$ 1,601
Common stock used to secure promissory note under separate stock pledge agreements		1,536,000
Notes receivable bearing interest rate		2.97%
Notes receivable, expiry period		5 years
Payment received from principal amount of promissory notes and accrued interest	$ 1,601		$ 1,601