Supplemental Accumulated Other Comprehensive Loss Information - Reclassifications Out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of actuarial losses	$ 0.0	$ 2.4
Defined and Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Actuarial loss	0.2	0.4
Prior service benefit	(0.2)	(0.4)
Curtailment gain	0.0	(4.0)
Total before taxes	0.0	(4.0)
Less income tax expense	0.0	1.6
Total, net of tax	$ 0.0	(2.4)
Amortization of actuarial losses		$ 0.2