Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reserve for Doubtful Accounts [Member]
Valuation Allowance [Line Items]
Beginning Balance	$ 9	$ 9
Additions	3	4
Net Deductions and Other	4	4
Ending Balance	8	9
Deferred Tax Valuation Allowance [Member]
Valuation Allowance [Line Items]
Beginning Balance	853	856
Additions	64	74
Net Deductions and Other	96	77
Ending Balance	$ 821	$ 853