Long-Term Debt - Schedule of Notes Payable (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2017
2030 Notes
Debt Instrument [Line Items]
Principal	$ 1,500,000,000	$ 1,500,000,000
Less: debt issuance cost and debt discount, net of amortization	(17,000,000)	(18,000,000)
Net carrying amount	$ 1,483,000,000	1,482,000,000
Effective interest rate	1.53%
2022 Notes
Debt Instrument [Line Items]
Principal	$ 135,000,000	169,000,000	$ 782,500,000
Less: debt issuance cost and debt discount, net of amortization	(7,000,000)	(11,000,000)
Net carrying amount	$ 128,000,000	$ 158,000,000
Effective interest rate	4.75%