Employee Benefit Plans (Details) (Other Postretirement Benefit Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 3	$ 4	$ 10	$ 12
Expected return on plan assets	(2)	(2)	(5)	(5)
Amortization of loss	1	1	3	2
Amortization of transition obligation	2	2	4	5
Net periodic cost	4	5	12	14
Expected contribution to postretirement benefit plan in current year			7
Total contribution to the plan during the period	$ 2		$ 6