Retirement Benefits Plans (Amounts Recognized as Components of Other Comprehensive (Loss) Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Retirement benefit plan funded status adjustments:
Actuarial gains (losses)	$ 5.2	$ (4.0)	$ (1.9)
Total	0.4	2.6	(5.7)
Defined Benefit Plan
Reclassifications to earnings of:
Actuarial loss amortization	0.5	0.5	1.0
Prior service benefit amortization	0.0	0.0	0.0
Curtailment gain	0.0	0.0	0.0
Settlement loss	12.6	0.0	0.0
Retirement benefit plan funded status adjustments:
Actuarial gains (losses)	(0.9)	3.9	(5.6)
Prior service cost	0.0	(0.5)	0.0
Total	14.0	(3.9)	6.6
Postretirement Benefit Plans
Reclassifications to earnings of:
Actuarial loss amortization	0.8	0.9	1.5
Prior service benefit amortization	(1.2)	(5.6)	(5.7)
Curtailment gain	(4.1)	(2.5)	0.0
Settlement loss	0.0	0.0	0.0
Retirement benefit plan funded status adjustments:
Actuarial gains (losses)	1.4	(0.2)	(3.9)
Prior service cost	0.0	0.0	0.0
Total	$ (5.9)	$ (7.0)	$ (0.3)