Other Income, Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other Income and Expenses [Abstract]
Interest income	$ 5	$ 4
Other nonoperating income	1	4
Defined Benefit Plan, Non-service Costs	(5)	(6)
Insurance policy expense	0	(1)
Other income, net	$ 1	$ 1