Employee Benefit Plans (Net Periodic Pension Costs Included in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
After-Tax Amount
Net losses reclassified from accumulated other comprehensive loss	$ (4.2)	$ (2.4)
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Before-Tax Amount
Accumulated other comprehensive loss as of December 31, 2016	(404.8)
Accumulated other comprehensive loss as of March 31, 2017	(401.4)
Income Tax
Accumulated other comprehensive loss as of December 31, 2016	(100.3)
Accumulated other comprehensive loss as of March 31, 2017	(99.8)
After-Tax Amount
Accumulated other comprehensive loss as of December 31, 2016	(304.5)
Accumulated other comprehensive loss as of March 31, 2017	(301.6)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member]
Before-Tax Amount
Amortization of prior service cost and net actual loss	3.0
Income Tax
Amortization of prior service cost and net actual loss	0.5
After-Tax Amount
Net losses reclassified from accumulated other comprehensive loss	2.5
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Including Portion Attributable to Noncontrolling Interest [Member]
Before-Tax Amount
Amortization of prior service cost and net actual loss	0.4
Income Tax
Amortization of prior service cost and net actual loss	0.0
After-Tax Amount
Net losses reclassified from accumulated other comprehensive loss	$ 0.4