Summary of Significant Accounting Policies (Detail) - Concentration of risk raw material purchases	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Vendor A [Member]
Purchase Of Raw Material, Concentration of Risk, Percentage	14.00%	17.00%
Vendor B [Member]
Purchase Of Raw Material, Concentration of Risk, Percentage	11.00%	8.00%
Vendor C [Member]
Purchase Of Raw Material, Concentration of Risk, Percentage	8.00%	11.00%
Vendor D [Member]
Purchase Of Raw Material, Concentration of Risk, Percentage	11.00%	5.00%