Income Taxes (Summary of Operating Loss And Tax Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2018 USD ($)
Operating Loss Carryforwards [Line Items]
Operating loss and tax credit carryforwards	$ 885
Operating Loss Carryforwards, Valuation Allowance	(398)
Operating Loss and Tax Credit Carryforwards, net	487
2019 Through 2028
Operating Loss Carryforwards [Line Items]
Operating loss and tax credit carryforwards	297
Operating Loss Carryforwards, Valuation Allowance	(192)
Operating Loss and Tax Credit Carryforwards, net	105
2029 Through 2038
Operating Loss Carryforwards [Line Items]
Operating loss and tax credit carryforwards	53
Operating Loss Carryforwards, Valuation Allowance	(8)
Operating Loss and Tax Credit Carryforwards, net	45
Indefinite
Operating Loss Carryforwards [Line Items]
Operating loss and tax credit carryforwards	535
Operating Loss Carryforwards, Valuation Allowance	(198)
Operating Loss and Tax Credit Carryforwards, net	337
U.S. federal and non-U.S. NOLs
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	470
U.S. federal and non-U.S. NOLs | 2019 Through 2028
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	53
U.S. federal and non-U.S. NOLs | 2029 Through 2038
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	0
U.S. federal and non-U.S. NOLs | Indefinite
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	417
State taxing jurisdiction NOLs (a)
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	122	[1]
Tax credit carryforwards	2	[1]
State taxing jurisdiction NOLs (a) | 2019 Through 2028
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	80	[1]
Tax credit carryforwards	2	[1]
State taxing jurisdiction NOLs (a) | 2029 Through 2038
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	42	[1]
Tax credit carryforwards	0	[1]
State taxing jurisdiction NOLs (a) | Indefinite
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	0	[1]
Tax credit carryforwards	0	[1]
U.S. federal, non- U.S. and state tax credit carryforwards (a)
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	291	[1]
U.S. federal, non- U.S. and state tax credit carryforwards (a) | 2019 Through 2028
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	162	[1]
U.S. federal, non- U.S. and state tax credit carryforwards (a) | 2029 Through 2038
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	11	[1]
U.S. federal, non- U.S. and state tax credit carryforwards (a) | Indefinite
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 118	[1]

[1] State amounts are presented net of federal benefit.