Supplemental Accumulated Other Comprehensive Loss Information - Reclassifications Out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Actuarial loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total expense before taxes	$ 0.2	$ 0.2
Prior service benefit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total expense before taxes	(0.2)	(0.2)
Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total expense before taxes	0.0	0.0
Less income tax benefit	0.0	0.0
Total expense, net of tax	$ 0.0	$ 0.0