Cash, Cash Equivalents, and Investments - Gross Unrealized Losses and Fair Values for Available-for-Sale Investments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 28, 2014
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	$ 156,561
Unrealized Losses, Less than 12 Months	(214)
Fair Value, 12 Months or Greater	6,363
Unrealized Losses, 12 Months or Greater	(14)
Total Fair Value	162,924
Total Unrealized Losses	(228)
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	59,613
Unrealized Losses, Less than 12 Months	(143)
Fair Value, 12 Months or Greater	1,709
Unrealized Losses, 12 Months or Greater	(1)
Total Fair Value	61,322
Total Unrealized Losses	(144)
Treasury Bills
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	67,615
Unrealized Losses, Less than 12 Months	(29)
Fair Value, 12 Months or Greater	0
Unrealized Losses, 12 Months or Greater	0
Total Fair Value	67,615
Total Unrealized Losses	(29)
Asset-Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	18,415
Unrealized Losses, Less than 12 Months	(24)
Fair Value, 12 Months or Greater	4,654
Unrealized Losses, 12 Months or Greater	(13)
Total Fair Value	23,069
Total Unrealized Losses	(37)
Agency Bonds
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	5,765
Unrealized Losses, Less than 12 Months	(6)
Fair Value, 12 Months or Greater	0
Unrealized Losses, 12 Months or Greater	0
Total Fair Value	5,765
Total Unrealized Losses	(6)
Sovereign Bonds
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	5,153
Unrealized Losses, Less than 12 Months	(12)
Fair Value, 12 Months or Greater	0
Unrealized Losses, 12 Months or Greater	0
Total Fair Value	5,153
Total Unrealized Losses	$ (12)