Pension Benefits - Changes in Fair Value of Plan Assets and Changes in Accumulated Benefit Obligations (Details) (Pension Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Year	$ 457.6	$ 441.3
Actual Return on Plan Assets	34.5	38.0
Employer Contributions	55.0	0
Benefits Paid	(22.6)	(21.5)
Settlement Benefits	0	(0.2)
Fair Value of Plan Assets at End of Year	524.5	457.6
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligations at Beginning of Year	553.9	499.2
Service Cost	10.8	10.8
Interest Cost	22.4	22.4
Benefits Paid	(22.6)	(21.5)
Settlement Benefits	0	(0.2)
Actuarial Losses	49.0	(43.2)
Benefit Obligations at End Of Year	515.5	553.9
Funded Status - Benefit Obligation In Excess of Plan Assets	9.0	(96.3)
Amount Recognized in Accumulated Other Comprehensive Income:
Accumulated Actuarial Loss	(86.3)	(166.4)
Prior Service Cost	0	0.1
Amount Recognized in Accumulated Other Comprehensive Income	(86.3)	(166.3)
Accumulated Benefit Obligation	$ 496.2	$ 531.3