SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for loss on receivables:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 69	$ 79	$ 96
Acquired/(Disposed) Balances	0	0	0
Charged (Credited)  to Costs and Expenses	36	(1)	36
Charged to Other Accounts	(1)	0	(29)
Deductions or Write-offs	(32)	(9)	(24)
Balance at End of Period	72	69	79
Deferred tax asset valuation allowance:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	45	54	49
Acquired/(Disposed) Balances	0	0	0
Charged (Credited)  to Costs and Expenses	8	9	(5)
Charged to Other Accounts	0	0	0
Deductions or Write-offs	0	0	0
Balance at End of Period	$ 37	$ 45	$ 54