Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 4,435,203	$ 2,042,306
Total changes in other comprehensive income (loss)	5,341	(4,051)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		9,229	$ (40,310)
Ending Balance	4,723,313	2,430,821
Foreign Currency Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(11,227)	(21,031)
Other comprehensive income before reclassifications	4,967	(2,729)
Amounts reclassified from accumulated other comprehensive income	0	0
Total changes in other comprehensive income (loss)	4,967	(2,729)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		949
Ending Balance	(6,260)	(22,811)
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	596	(460)
Amounts reclassified from accumulated other comprehensive income	0	0
Total changes in other comprehensive income (loss)	596	(460)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		0
Ending Balance	60	(1,054)
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		0
Total changes in other comprehensive income (loss)		0
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		(25,069)
Ending Balance		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		(7,639)
Amounts reclassified from accumulated other comprehensive income		6,777
Total changes in other comprehensive income (loss)		(862)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		0
Ending Balance		(15,878)
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	5,126
Amounts reclassified from accumulated other comprehensive income	(5,348)
Total changes in other comprehensive income (loss)	(222)
Ending Balance	12,200
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	659	(11,572)
Other comprehensive income before reclassifications	10,689	(10,828)
Amounts reclassified from accumulated other comprehensive income	(5,348)	6,777
Total changes in other comprehensive income (loss)	5,341	(4,051)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		(24,120)
Ending Balance	$ 6,000	$ (39,743)