Accumulated Other Comprehensive Income (Loss) - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Equity [Abstract]
Pension and other postretirement benefit plans, tax benefit (expense)		$ (1.8)	$ (0.1)
Cumulative pension and other postretirement benefit plans, tax expense (benefits)	$ 3.6	15.2	3.6
Unrealized gain (loss) on derivatives, income tax expense (benefit)		2.8	0.4
Cumulative unrealized gain (loss) on derivatives, income tax expense (benefit)	1.5	$ 2.6	1.5
Curtailment gain	$ (5.7)		$ (11.3)