Pensions and Other Postretirement Benefits-Projected Benefit Obligation (Details) - Postretirement Plans Other Than Pensions [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Accumulated benefit obligation at beginning of year	$ 53	$ 55
Interest cost	2	2	$ 2
Actuarial losses (gains)	(8)	0
Benefits paid, net	(5)	(4)
Accumulated benefit obligation at end of year	$ 42	$ 53	$ 55