Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Components of net periodic cost (income)
Settlement loss	$ 0	$ (2)	$ 0	$ (2)
Other Postretirement Benefit Expense	1		1
Savings plan expenses	3	3	6	5
Pension
Components of net periodic cost (income)
Interest cost	6	2	8	5
Expected return on plan assets	(8)	(3)	(11)	(6)
Settlement loss	0	2	0	2
Amortization of net loss	0	0	1	0
Net periodic cost (income)	(2)	1	(2)	1
Qualified Pension Plan
Components of net periodic cost (income)
Cash contributions	1	2	2	9
Estimated employer contributions in current year			$ 4
Non Qualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Number of pension plans	2		2