Employee Benefit Plans (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pension Benefits [Member]
Components of Net Periodic Benefit Cost
Service Cost	$ 2	$ 2	$ 7	$ 6
Interest Cost	4	4	12	11
Expected Return on Plan Assets	(4)	(3)	(12)	(10)
Amortization of Prior Service Cost			0	0
Amortization of Net Loss	2	1	5	4
Net Periodic Benefit Cost	4.0	4.0	12.0	11.0
Other Postretirement Benefits [Member]
Components of Net Periodic Benefit Cost
Service Cost	1	0	2	2
Interest Cost	1	1	3	3
Expected Return on Plan Assets	0	0	0	0
Amortization of Prior Service Cost			(1)	(1)
Amortization of Net Loss	0	0	0	0
Net Periodic Benefit Cost	$ 2.0	$ 1.0	$ 4.0	$ 4.0