Income Taxes (Unrecognized Tax Benefits That Would/Not Reduce The Effective Tax Rate) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unrecognized Tax Benefits That Would Impact Effective Tax Rate [Abstract]
Unrecognized tax benefits that would reduce the effective tax rate	$ 39	$ 63	$ 83
Unrecognized tax benefits that would not reduce the effective tax rate	25	111	96
Total unrecognized tax benefits	$ 64	$ 174	$ 179	$ 125