Components of Convertible Senior Notes (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Oct. 02, 2011	Sep. 30, 2012	Oct. 02, 2011	Dec. 31, 2011
Debt Instrument
Debt principal	$ 190,000		$ 190,000		$ 190,000
Unamortized debt discount	23,732		23,732		33,902
Net carrying amount of the convertible debt	166,268		166,268		156,098
Contractual interest expense	2,114	2,114	6,413	6,460
Amortization of the discount component and debt issue fees	3,710	3,263	10,781	9,484
Total interest expense on the convertible debt	$ 5,824	$ 5,377	$ 17,194	$ 15,944