Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 31	$ 37	$ 41
Charged to Costs & Expenses	24	14	10
Charged to Other Accounts	0	0	0
Deductions	11	20	14
Balance at End of Period	44	31	37
Deferred Tax Asset Valuation Allowance [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	485	415	445
Charged to Costs & Expenses	23	100	0
Charged to Other Accounts	0	0	0
Deductions	156	30	30
Balance at End of Period	$ 352	$ 485	$ 415