Pension and Other Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended						1 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Pension Plans, Defined Benefit [Member]	Mar. 31, 2012 Pension Plans, Defined Benefit [Member]	Mar. 31, 2013 Other Postretirement Benefit Plans, Defined Benefit [Member]	Mar. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member]	Apr. 30, 2013 Subsequent Event [Member] Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Estimated Employer Contributions in Current Fiscal Year			$ 181.5
Pension plan contributions	30.0	28.7	30.0				41.3
Defined Benefit Plan, Estimated Employer Contributions Remaining to be Made in Current Fiscal Year							110.2
Contributions to retirees VEBAs					30.8
Net periodic benefit cost (income) [Abstract]
Service cost			0.6	0.8	1.2	1.1
Interest cost			34.7	40.1	5.3	7.9
Expected return on assets			(45.9)	(46.3)
Amortization of prior service cost (credit)			0.9	1.1	(20.0)	(19.3)
Amortization of (gain) loss			6.8	6.1	0.5	0
Net periodic benefit cost (income)	$ (15.9)	$ (8.5)	$ (2.9)	$ 1.8	$ (13.0)	$ (10.3)