Schedule of Revenue by Major Customers (Detail)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Customer A
Revenue, Major Customer [Line Items]
Percentage of total revenue	15.00%		15.00%		27.50%
Customer B
Revenue, Major Customer [Line Items]
Percentage of total revenue	33.30%		37.50%		34.30%
Customer C
Revenue, Major Customer [Line Items]
Percentage of total revenue		[1]		[1]	11.10%

[1] Less than 10 percent.