Postretirement and Other Benefits Net Periodic Cost (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits
Components of Net Periodic Cost:
Service Cost	$ 12.6	$ 16.3	$ 18.3
Interest Cost	57.9	52.2	51.1
Expected Return on Plan Assets	(79.8)	(68.0)	(58.1)
Amortization:
Prior Service Cost (Credit)	0.7	0.7	0.7
Actuarial Loss (Gain)	13.2	36.1	30.1
Net Curtailment/Settlement Loss	0.8	0	0
Special Termination Benefit	0	1.2	0
Other	0.6	0.7	0.4
Net Periodic Cost	6.0	39.2	42.5
Postretirement Health Care Benefits
Components of Net Periodic Cost:
Service Cost	1.2	1.2	1.2
Interest Cost	2.2	2.0	2.3
Expected Return on Plan Assets	0	0	0
Amortization:
Prior Service Cost (Credit)	(0.3)	(0.4)	(0.2)
Actuarial Loss (Gain)	(1.0)	(1.1)	(1.4)
Net Curtailment/Settlement Loss	0	0	0
Special Termination Benefit	0	0	0
Other	0	0	(0.1)
Net Periodic Cost	$ 2.1	$ 1.7	$ 1.8