Summary of Significant Accounting Policies- Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Schedule Of Significant Accounting Policies [Line Items]
Allowance for doubtful accounts	$ 559		$ 559		$ 641
Shipping and handling costs	$ 6,014	$ 5,665	$ 17,512	$ 16,567