Debt - Schedule of Convertible Senior Notes (Details) - Convertible Debt - USD ($)	Jun. 30, 2021	Dec. 31, 2020	Aug. 31, 2019	May 31, 2018
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	(182,791,000)	(196,359,000)
Net carrying amount	967,209,000	953,641,000
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	(176,096,000)	(196,934,000)
Net carrying amount	973,904,000	953,066,000
Equity component:	$ 285,225,000	$ 285,225,000