Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012		Jul. 01, 2012	Dec. 31, 2011	Mar. 31, 2009
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents, Carrying Value	$ 227,601		$ 338,920		$ 589,056	$ 573,736
Convertible debt, Carrying Value	177,532		169,896
Japan loan, Carrying Value							10,000
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents, Carrying Value	227,601		338,920
Marketable securities, Carrying Value	803,994		667,388
Convertible debt, Carrying Value	177,532	[1]	169,896	[1]
Japan loan, Carrying Value	2,033		3,491
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents, Fair Value	227,601		338,920
Marketable securities, Fair Value	803,994		667,388
Convertible debt, Fair Value	610,726	[1]	589,000	[1]
Japan loan, Fair Value	$ 2,033		$ 3,491

[1] The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note which includes the equity conversion feature.