Cash, Cash Equivalents, and Investments - Components of Cash, Cash Equivalents, and Investments (Detail) - USD ($) $ in Thousands	Oct. 04, 2015	Dec. 31, 2014	Sep. 28, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Cash	$ 47,146	$ 54,917
Money market instruments	32,417	777
Cash and cash equivalents	79,563	55,694	$ 38,179	$ 40,644
Short-term investments	272,584	90,456
Limited partnership interest	942	1,956
Long-term investments	240,504	400,845
Total	592,651	546,995
Treasury Bills
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	82,401	0
Long-term investments	16,580	90,412
Euro Liquidity Fund
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	63,672	48,235
Asset-Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	60,992	1,311
Long-term investments	28,254	62,556
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	45,170	30,889
Long-term investments	181,842	216,294
Agency Bonds
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	10,980	6,883
Long-term investments	3,300	9,566
Sovereign Bonds
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	7,568	0
Long-term investments	4,702	13,461
Municipal Bonds
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	1,801	1,237
Long-term investments	4,884	6,600
Supranational Bonds
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	$ 0	$ 1,901