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	$ 8
Additions	4	5
Net Deductions and Other	4	4
Ending Balance	9	9
Deferred Tax Valuation Allowance [Member]
Valuation Allowance [Line Items]
Beginning Balance	856	1,209
Additions	74	140
Net Deductions and Other	77	493
Ending Balance	$ 853	$ 856