Income Taxes - Components of deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets [Abstract]
Accruals and reserves	$ 105,411	$ 83,805
Net operating loss carryforwards	78,489	4,083
Tax credit carryforwards	80,462	38,411
Stock-based compensation	60,570	33,194
Other	15,645	11,352
Total deferred tax assets	340,577	170,845
Less: valuation allowance	(102,123)	(43,671)
Net deferred tax assets	238,454	127,174
Deferred tax liability [Abstract]
Prepaid expenses	(4,651)	(3,891)
Intangible assets	(110,089)	(17,863)
Depreciation	(51,933)	(20,740)
Other	(1,909)	(2,123)
Total deferred tax liabilities	(168,582)	(44,617)
Total net deferred tax assets	69,872	82,557
Increase in valuation allowance	$ 58,500	$ 16,400