Pension and Other Postretirement Benefits-Post Retirement Benefit Cost (Details) - Other Postretirement Benefit Plan, Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Interest Cost	$ 2	$ 2	$ 3	$ 4
Net periodic postretirement benefit cost	$ 2	$ 2	$ 3	$ 4