Pension and Other Postretirement Benefits-Post Retirement Benefit Cost (Details) - Other Postretirement Benefit Plan, Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Interest Cost	$ 4	$ 5	$ 7
Amortization of reduction in liability resulting from plan amendment	(6)	(3)	0
Gain from curtailment	(5)	0	0
Net periodic postretirement benefit cost	$ (7)	$ 2	$ 7