Derivative Financial Instruments and Risk Management (Details 5) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Offsetting Assets and Liabilities [Abstract]
Gross Amount of Recognized Assets	$ 83	$ 22
Gross Amounts Offset	0	0
Net Amount of Assets	83	22
Gross Amounts Not Offset	(13)	(10)
Net Amount	70	12
Gross Amount of Recognized Liabilities	(39)	(68)
Gross Amounts Offset	0	0
Net Amount of Liabilities	(39)	(68)
Gross Amounts Not Offset	13	10
Net Amount	$ (26)	$ (58)