Employee Benefit Plans (Net Periodic Pension Costs Included in Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Before-Tax Amount
Accumulated other comprehensive loss, beginning of period	$ (341.5)
Amortization of net actuarial loss	2.8
Amortization of prior service cost	0.1
Accumulated other comprehensive loss, end of period	(338.6)
Income Tax
Accumulated other comprehensive loss, beginning of period	(88.2)
Amortization of net actuarial loss	0.7
Amortization of prior service cost	0
Accumulated other comprehensive loss, end of period	(87.5)
After-Tax Amount
Accumulated other comprehensive loss, beginning of period	(253.3)
Amortization of net actuarial loss	2.1
Amortization of prior service costs	0.1
Accumulated other comprehensive loss, end of period	$ (251.1)