Income Taxes (Unrecognized Tax Benefit Reflected In Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ (306)	$ (286)	$ (317)
Income Tax Receivable [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	(45)	(21)
Other Liabilities and Provisions [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	(202)	(193)
Deferred Income Tax Liabilities (Assets) [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ (59)	$ (72)