Fair Value Measurements - Schedule of Carrying Values and Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2021	Jun. 30, 2020	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents			$ 581	$ 1,442
Restricted cash			46	59
Less current portion of long-term debt			244	140
Long-term debt			6,685	3,160
Equity component	$ (202)	$ 230
Deferred tax provision	44	(25)
Additional Paid-in Capital
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity component	(230)	230	(230)
Deferred tax provision	$ 50	$ (25)	50
Convertible debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt			1,305	1,100
Senior notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt			5,380	2,060
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Less current portion of long-term debt			249	140
Estimate of Fair Value Measurement | Convertible debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt			2,139	1,756
Estimate of Fair Value Measurement | Senior notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt			5,469	2,230
Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value			$ 581	$ 1,442