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, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Interest Cost	$ 5	$ 7	$ 7
Amortization of reduction in liability resulting from plan amendment	(3)	0	0
Net periodic postretirement benefit cost	$ 2	$ 7	$ 7