Schedule of Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Jul. 01, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 803,061	$ 1,470,729
Available-for-sale marketable securities, Unrealized Gain	707	6,582
Available-for-sale marketable securities, Unrealized (Loss)	(3,331)	(3,406)
Available-for-sale marketable securities, Fair Market Value	800,437	1,473,905
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	691,584	1,350,895
U.S. Treasury Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	530,944	858,258
Available-for-sale marketable securities, Unrealized Gain	29	72
Available-for-sale marketable securities, Unrealized (Loss)	(2,116)	(2,535)
Available-for-sale marketable securities, Fair Market Value	528,857	855,795
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	477,385	850,163
Commercial Paper
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	218,594	283,009
Available-for-sale marketable securities, Unrealized Gain	9	18
Available-for-sale marketable securities, Unrealized (Loss)	(83)	(187)
Available-for-sale marketable securities, Fair Market Value	218,520	282,840
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	184,349	258,933
Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	38,709	131,179
Available-for-sale marketable securities, Unrealized Gain	668	2,380
Available-for-sale marketable securities, Unrealized (Loss)	(1,005)	(373)
Available-for-sale marketable securities, Fair Market Value	38,372	133,186
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	20,956	91,010
U.S. Government Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	10,066	10,775
Available-for-sale marketable securities, Unrealized Gain	1
Available-for-sale marketable securities, Unrealized (Loss)	(58)	(49)
Available-for-sale marketable securities, Fair Market Value	10,009	10,726
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	7,034	10,726
Debt Mutual Funds
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	2,878
Available-for-sale marketable securities, Unrealized (Loss)	(68)
Available-for-sale marketable securities, Fair Market Value	2,810
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	1,681
Equity and Debt Mutual Funds
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost		19,403
Available-for-sale marketable securities, Unrealized Gain		4,102
Available-for-sale marketable securities, Unrealized (Loss)		(75)
Available-for-sale marketable securities, Fair Market Value		23,430
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses		1,723
Certificates of Deposit and Time Deposits
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	1,318	167,523
Available-for-sale marketable securities, Unrealized Gain		6
Available-for-sale marketable securities, Unrealized (Loss)		(187)
Available-for-sale marketable securities, Fair Market Value	1,318	167,342
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses		138,340
Non-U.S. Government Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	552	582
Available-for-sale marketable securities, Unrealized Gain		4
Available-for-sale marketable securities, Unrealized (Loss)	(1)
Available-for-sale marketable securities, Fair Market Value	551	$ 586
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	$ 179