Cash Equivalents and Investments - Company's Cash Equivalents and Investments Measured at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 29, 2013	Dec. 31, 2012
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Cash equivalents measured at fair value		$ 371,075
Investments measured at fair value	268,382	204,457
Money-market funds [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Cash equivalents measured at fair value	262,359	364,596
Agency securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	142,420	129,463
Non-agency securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	658	1,393
Government and agency securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Cash equivalents measured at fair value		6,479
Investments measured at fair value	95,606	66,700
Corporate debt securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	18,967	6,001
Commercial paper [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	10,731	900
Long-term investments in equity securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	2,687	1,689
Level 1 [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Cash equivalents measured at fair value		364,596
Investments measured at fair value	35,680	17,042
Level 1 [Member] | Money-market funds [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Cash equivalents measured at fair value	262,359	364,596
Level 1 [Member] | Government and agency securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	35,680	17,042
Level 1 [Member] | Long-term investments in equity securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	2,687	1,689
Level 2 [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Cash equivalents measured at fair value		6,479
Investments measured at fair value	232,702	187,415
Level 2 [Member] | Agency securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	142,420	129,463
Level 2 [Member] | Non-agency securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	658	1,393
Level 2 [Member] | Government and agency securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Cash equivalents measured at fair value		6,479
Investments measured at fair value	59,926	49,658
Level 2 [Member] | Corporate debt securities [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	18,967	6,001
Level 2 [Member] | Commercial paper [Member]
Company's Cash Equivalents and Investments measured at Fair Value [Line Items]
Investments measured at fair value	$ 10,731	$ 900