Comprehensive Income (Reclassifications out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net										$ (1,076)	$ 8,373	$ (3,150)
Operating expenses										2,010,399	1,862,140	1,814,043
Net income		$ (207,113)	$ (270,857)	$ (93,495)	$ (110,348)	$ (165,718)	$ (158,857)	$ (106,833)	$ (144,259)	(681,813)	$ (575,667)	$ 20,719
Amount reclassified from Accumulated other comprehensive loss, net of tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income										1,036
Amount reclassified from Accumulated other comprehensive loss, net of tax | Unrealized net gains on available-for-sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net										(580)
Amount reclassified from Accumulated other comprehensive loss, net of tax | Unrealized net losses on cash flow hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operating expenses	[1]									$ 1,616

[1] Operating expenses amounts allocated to Research and development, Sales, marketing and services, and General and administrative are not individually significant.