Derivative Financial Instruments and Risk Management (Details 5) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Offsetting Assets and Liabilities [Abstract]
Gross Amount of Recognized Assets	$ 17	$ 22
Gross Amounts Offset	0	0
Net Amount of Assets	17	22
Gross Amounts Not Offset	(4)	(10)
Net Amount	13	12
Gross Amount of Recognized Liabilities	(116)	(68)
Gross Amounts Offset	0	0
Net Amount of Liabilities	(116)	(68)
Gross Amounts Not Offset	4	10
Net Amount	$ (112)	$ (58)