Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		12 Months Ended
	Aug. 15, 2006	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Aug. 18, 2006	Jun. 15, 2005
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period		$ (61.8)	$ (31.5)
Other comprehensive gain (loss) before reclassification		(26.6)	(35.0)
Amounts reclassified from accumulated other comprehensive loss		4.0	3.1
Income tax benefit (expense)		(2.7)	1.6
Other comprehensive income (loss)		(25.3)	(30.3)	$ 4.0
Balance at the end of the period		(87.1)	(61.8)	(31.5)
Remaining unamortized gain reflected in accumulated other comprehensive income (loss) resulting from termination of treasury lock contracts, before tax		0.4
Remaining unamortized gain reflected in accumulated other comprehensive income (loss) resulting from termination of treasury lock contracts, after tax		0.3
6.125% senior notes due 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Par value of senior notes		150.0			$ 150.0
Cash flow hedge
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Notional amount of treasury lock contracts to hedge cash flow variability on forecasted debt interest payments associated with changes in interest rates						$ 150.0
Amortization of gain resulting from termination of treasury lock contracts, net of tax	$ 3.5
Cash flow hedge | Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss related to settlement costs	$ 5.6
Accrued post-retirement benefit liability
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period		(32.0)	(28.2)
Other comprehensive gain (loss) before reclassification		3.0	(8.9)
Amounts reclassified from accumulated other comprehensive loss		4.5	3.7
Income tax benefit (expense)		(2.9)	1.4
Other comprehensive income (loss)		4.6	(3.8)
Balance at the end of the period		(27.4)	(32.0)	(28.2)
Foreign currency translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period		(30.4)	(4.3)
Other comprehensive gain (loss) before reclassification		(29.6)	(26.1)
Other comprehensive income (loss)		(29.6)	(26.1)
Balance at the end of the period		(60.0)	(30.4)	(4.3)
Hedging activities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period		0.6	1.0
Amounts reclassified from accumulated other comprehensive loss		(0.5)	(0.6)
Income tax benefit (expense)		0.2	0.2
Other comprehensive income (loss)		(0.3)	(0.4)
Balance at the end of the period		$ 0.3	$ 0.6	$ 1.0