Derivative and Other Financial Instruments (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amounts Recognized in the Balance Sheet, Derivative Assets	$ 49	$ 42
Gross Amounts Not Offset in the Balance Sheet, Derivative Assets	10	9
Net Amount, Derivative Assets	39	33
Gross Amounts Recognized in the Balance Sheet, Derivative Liabilities	36	52
Gross Amounts Not Offset in the Balance Sheet, Derivative Liabilities	10	9
Net Amount, Derivative Liabilities	$ 26	$ 43