Derivative Financial Instruments and Risk Management (Details 5) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Offsetting Assets and Liabilities [Abstract]
Gross Amount of Recognized Assets	$ 140	$ 22
Gross Amounts Offset	0	0
Net Amount of Assets	140	22
Gross Amounts Not Offset	(31)	(10)
Net Amount	109	12
Gross Amount of Recognized Liabilities	(39)	(68)
Gross Amounts Offset	0	0
Net Amount of Liabilities	(39)	(68)
Gross Amounts Not Offset	31	10
Net Amount	$ (8)	$ (58)