Fair Value of Financial Instruments (Schedule of the Fair Value of Derivative Instruments in the Consolidated Balance Sheet) (Details) - Designated as Hedging Instrument [Member] - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives designated as hedging instruments
Other Long-term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability derivatives designated as hedging instruments	$ 33	$ 49