Debt - Schedule of Convertible Senior Notes (Details) - Convertible Debt - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Aug. 31, 2019	May 31, 2018	Feb. 28, 2014
2027 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	(196,359,000)	(222,928,000)
Net carrying amount	953,641,000	927,072,000
Equity component:	220,529,000	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	(196,934,000)	(237,281,000)
Net carrying amount	953,066,000	912,719,000
Equity component:	$ 285,225,000	$ 285,225,000
2019 Notes
Liability component:
Principal					$ 690,000,000.0