Schedule II Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Allowance, Notes Receivable [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	$ 8	$ 9	$ 8	$ 14
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense	1	2	2
SEC Schedule, 12-09, Valuation Allowances and Reserves, Increase (Decrease) Adjustment	0	0	0
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	(2)	(1)	(8)
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	72	65	73	$ 77
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense	8	4	6
SEC Schedule, 12-09, Valuation Allowances and Reserves, Increase (Decrease) Adjustment	0	1	(4)
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	$ (1)	$ (13)	$ (6)