Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Accumulated balances for each classification of comprehensive income (loss)
Balance at the beginning of the period	$ (35.5)	$ (45.0)
Other comprehensive income (loss) before reclassifications	(9.8)	4.3
Amounts reclassified from accumulated other comprehensive loss	1.3	1.2
Income tax expense	(0.5)	(0.5)
Other comprehensive income (loss)	(9.0)	5.0
Balance at the end of the period	(44.5)	(40.0)
Accrued post-retirement benefit liability
Accumulated balances for each classification of comprehensive income (loss)
Balance at the beginning of the period	(34.1)	(40.7)
Other comprehensive income (loss) before reclassifications	0.5
Amounts reclassified from accumulated other comprehensive loss	1.4	1.3
Income tax expense	(0.5)	(0.5)
Other comprehensive income (loss)	1.4	0.8
Balance at the end of the period	(32.7)	(39.9)
Foreign currency translation
Accumulated balances for each classification of comprehensive income (loss)
Balance at the beginning of the period	(2.7)	(5.9)
Other comprehensive income (loss) before reclassifications	(10.3)	4.3
Other comprehensive income (loss)	(10.3)	4.3
Balance at the end of the period	(13.0)	(1.6)
Hedging activities
Accumulated balances for each classification of comprehensive income (loss)
Balance at the beginning of the period	1.3	1.6
Amounts reclassified from accumulated other comprehensive loss	(0.1)	(0.1)
Other comprehensive income (loss)	(0.1)	(0.1)
Balance at the end of the period	$ 1.2	$ 1.5