Pensions and Other Postretirement Benefits-Projected Benefit Obligation (Details) - Postretirement Plans Other Than Pensions [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Accumulated benefit obligation at beginning of year	$ 60	$ 62
Interest cost	2	2	$ 3
Actuarial losses (gains)	(3)	4
Benefits paid	(4)	(4)
Plan amendments	0	(4)
Accumulated benefit obligation at end of year	$ 55	$ 60	$ 62
Remaining amortization period for plan amendment		7 years