Debt - Schedule of Convertible Senior Notes (Details) - Convertible Debt - USD ($)	Dec. 31, 2019	Aug. 31, 2019	Dec. 31, 2018	May 31, 2018	Feb. 28, 2014
2027 Notes
Liability component:
Principal	$ 1,150,000,000	$ 1,150,000,000.0
Less: debt discount and issuance costs, net of amortization	(222,928,000)
Net carrying amount	927,072,000
Equity component:	220,529,000
2025 Notes
Liability component:
Principal	1,150,000,000		$ 1,150,000,000	$ 1,150,000,000.0
Less: debt discount and issuance costs, net of amortization	(237,281,000)		(275,920,000)
Net carrying amount	912,719,000		874,080,000
Equity component:	$ 285,225,000		$ 285,225,000
2019 Notes
Liability component:
Principal					$ 690,000,000.0