Derivative and Other Financial Instruments (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amounts Recognized in the Balance Sheet, Derivative Assets	$ 80	$ 42
Gross Amounts Not Offset in the Balance Sheet, Derivative Assets	16	9
Net Amount, Derivative Assets	64	33
Gross Amounts Recognized in the Balance Sheet, Derivative Liabilities	59	52
Gross Amounts Not Offset in the Balance Sheet, Derivative Liabilities	16	9
Net Amount, Derivative Liabilities	$ 43	$ 43