Other Income (Expense), Net (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Components of other income and expense, nonoperating [Line Items]
Interest income	$ 0.1		$ 0.1
Unrealized gains on financial derivatives	0.4	[1]	0.5	[1]
Realized gains on investments	0.5		0
All other, net	0		0.1
Other non-operating income, net	$ 1.0		$ 0.7

[1] See “Hedges Relating to the Convertible Notes” in Note 8 for discussion of such instruments.