Long-term debt and interest expense, net (Details) - USD ($) $ in Millions	Dec. 31, 2020	Jul. 01, 2020	Dec. 31, 2019
Long-term debt and interest expenses
Debt discount and issuance costs	$ (57)		$ (54)
Obligations under finance leases and other	3		6
Total long-term debt	2,422		2,945
Current portion of long-term debt	(8)		(30)
Non-current portion of long-term debt	2,414		2,915
Term Loan B
Long-term debt and interest expenses
Long-term debt	1,444		1,960
2023 Notes
Long-term debt and interest expenses
Long-term debt	850		1,000
2027 Notes
Long-term debt and interest expenses
Long-term debt	150	$ 150
Deferred financing
Long-term debt and interest expenses
Long-term debt	$ 32		$ 33