Employee Benefit Plans (Details) (Other Postretirement Benefit Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 3	$ 4
Expected return on plan assets	(2)	(1)
Amortization of loss	1	0
Amortization of transition obligation	0	1
Net periodic cost	2	4
Expected contribution to postretirement benefit plan in current year	7
Total contribution to the plan during the period	$ 2