Income Taxes - Reconciliation of Federal Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Income Tax Disclosure [Abstract]
Tax computed at U.S. federal statutory rate	$ (8,195)	$ (38,558)		$ (139,542)
State taxes, net of federal benefit	98	64		37
Tax rate differential for international subsidiaries	(41,429)	23,532		8,020
Stock-based compensation	(93,073)	(116,953)		(27,133)
Tax credits	(44,695)	(21,038)		(16,452)
Foreign restructuring and amortization	(625,292)	2,794		3,169
Non-deductible expenses	9,657	2,833		1,892
Tax effects associated with Topic 606	(23,073)	3,314		2,076
Other	408	607		896
Valuation allowance	813,274	146,845		170,867
Provision for (benefit from) income taxes	$ (12,320)	$ 3,440	[1]	$ 3,830	[1]

[1] As adjusted to reflect the impact of the full retrospective adoption of Topic 606.