Schedule of Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 1,304,711	$ 745,498
Available-for-sale marketable securities, Unrealized Gain	2,977	2,145
Available-for-sale marketable securities, Unrealized (Loss)	(2,821)	(4,019)
Available-for-sale marketable securities, Fair Market Value	1,304,867	743,624
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	732,979	601,660
U.S. Treasury Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	901,975	421,060
Available-for-sale marketable securities, Unrealized Gain	97	65
Available-for-sale marketable securities, Unrealized (Loss)	(2,034)	(1,167)
Available-for-sale marketable securities, Fair Market Value	900,038	419,958
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	572,284	379,434
Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	99,708	163,297
Available-for-sale marketable securities, Unrealized Gain	1,065	902
Available-for-sale marketable securities, Unrealized (Loss)	(620)	(2,565)
Available-for-sale marketable securities, Fair Market Value	100,153	161,634
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	53,642	145,373
U.S. Government Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	42,026	84,032
Available-for-sale marketable securities, Unrealized Gain	7	42
Available-for-sale marketable securities, Unrealized (Loss)	(19)	(122)
Available-for-sale marketable securities, Fair Market Value	42,014	83,952
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	13,461	55,120
Certificates of Deposit and Time Deposits
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	82,080	43,391
Available-for-sale marketable securities, Unrealized Gain	54	6
Available-for-sale marketable securities, Unrealized (Loss)	(1)	(3)
Available-for-sale marketable securities, Fair Market Value	82,133	43,394
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	7,760	10,527
Commercial Paper
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	161,672	20,298
Available-for-sale marketable securities, Unrealized Gain	24	11
Available-for-sale marketable securities, Unrealized (Loss)	(66)	(1)
Available-for-sale marketable securities, Fair Market Value	161,630	20,308
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	84,034	8,646
Equity And Debt Mutual Funds
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	16,505	12,996
Available-for-sale marketable securities, Unrealized Gain	1,724	1,119
Available-for-sale marketable securities, Unrealized (Loss)	(58)	(161)
Available-for-sale marketable securities, Fair Market Value	18,171	13,954
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	1,661	2,560
Non-U.S. Government Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	745	424
Available-for-sale marketable securities, Unrealized Gain	6
Available-for-sale marketable securities, Unrealized (Loss)	(23)
Available-for-sale marketable securities, Fair Market Value	728	$ 424
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	$ 137

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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