Pension and Postretirement Health and Life Benefits (Schedule of Net Benefit Costs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Curtailment (gains)	$ (0.7)
Defined Benefit Pension Plans [Member]
Service costs	1.4	3.6	8.8	10.9
Interest costs	11.5	12.1	33.5	36.2
Expected return on plan assets (gains)	(12.8)	(12.9)	(38.3)	(38.9)
Amortization of prior service costs	0	0.3	0.7	1.1
Amortization of actuarial (gains) losses, net	2.0	5.0	14.2	14.8
Curtailment (gains)	0		(0.7)
Net benefit costs	2.1	8.1	18.2	24.1
Postretirement Health and Life Benefits Plans [Member]
Service costs	0.9	0.9	2.7	2.7
Interest costs	2.2	2.7	6.7	8.3
Expected return on plan assets (gains)	(0.5)	(0.7)	(1.7)	(2.1)
Amortization of actuarial (gains) losses, net	0.6	1.2	2.0	3.4
Net benefit costs	$ 3.2	$ 4.1	$ 9.7	$ 12.3