Employee Benefit Plans (Details) - Other Postretirement Benefit Plans [Member] - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost	[1]	$ 0	$ 0
Expected contribution to postretirement benefit plan in current year		10
Total contribution to the plan during the period		2
Other, net [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (1)		2	2
Expected return on plan assets (1)		(1)	(1)
Amortization of prior service credit (1)		$ (1)	$ (1)

[1] Included in Other, net in the Condensed Statements of Consolidated Income.