Pension and Other Postretirement Benefits-Projected Benefit Obligation (Details) - Other Postretirement Benefit Plan, Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Accumulated benefit obligation at beginning of year	$ 173	$ 174
Interest cost	5	7
Actuarial (gains) losses	(21)	5
Reduction in liability resulting from plan amendment	(46)	0
Benefits paid, net	(11)	(13)
Accumulated benefit obligation at end of year	$ 100	$ 173