SCHEDULE II Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Allowance, Credit Loss
Allowance for valuation and qualifying accounts
Balance at Beginning of Period	$ 36	$ 40	$ 31
Additions	56	9	9
Deductions	(12)	(13)	0
Balance at End of Period	86	36	40
SEC Schedule, 12-09, Allowance, Credit Loss | Accounting Standards Update 2019-11
Allowance for valuation and qualifying accounts
Balance at Beginning of Period	42
Balance at End of Period		42
Tax-Related valuation allowance
Allowance for valuation and qualifying accounts
Balance at Beginning of Period	209	245	159
Additions	119		86
Deductions		(36)
Balance at End of Period	$ 328	$ 209	$ 245