Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 4,723,313	$ 2,430,821	$ 4,435,203	$ 2,042,306
Total changes in other comprehensive (loss) income	(9,201)	35,138	(3,860)	31,087
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		9,229		9,229	$ (40,310)
Ending Balance	5,069,965	2,714,883	5,069,965	2,714,883
Foreign Currency Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance			(11,227)	(21,031)
Other comprehensive income before reclassifications			1,091	6,141
Amounts reclassified from accumulated other comprehensive income (loss)			0	0
Total changes in other comprehensive (loss) income			1,091	6,141
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		949		949
Ending Balance	(10,136)	(13,941)	(10,136)	(13,941)
Unrealized Holding Gains (Losses), Net of Tax, On Available-For-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance			(536)	(594)
Other comprehensive income before reclassifications			1,047	(87)
Amounts reclassified from accumulated other comprehensive income (loss)			0	0
Total changes in other comprehensive (loss) income			1,047	(87)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		0		0
Ending Balance	511	(681)	511	(681)
Unrealized Holding Gains (Losses), Net of Tax, On Equity Securities, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance				25,069
Other comprehensive income before reclassifications				0
Amounts reclassified from accumulated other comprehensive income (loss)				0
Total changes in other comprehensive (loss) income				0
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		(25,069)		(25,069)
Ending Balance		0		0
Unrealized Holding Gains (Losses), Net of Tax, On Foreign Currency Forward Contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance				(15,016)
Other comprehensive income before reclassifications				15,352
Amounts reclassified from accumulated other comprehensive income (loss)				9,681
Total changes in other comprehensive (loss) income				25,033
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		0		0
Ending Balance		10,017		10,017
Unrealized Holding Gains (Losses), Net of Tax, On Foreign Currency Forward Contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance			12,422
Other comprehensive income before reclassifications			5,793
Amounts reclassified from accumulated other comprehensive income (loss)			(11,791)
Total changes in other comprehensive (loss) income			(5,998)
Ending Balance	6,424		6,424
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	6,000	(39,743)	659	(11,572)
Other comprehensive income before reclassifications			7,931	21,406
Amounts reclassified from accumulated other comprehensive income (loss)			(11,791)	9,681
Total changes in other comprehensive (loss) income	(9,201)	35,138	(3,860)	31,087
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		(24,120)		(24,120)
Ending Balance	$ (3,201)	$ (4,605)	$ (3,201)	$ (4,605)