Schedule II Valuation and Qualifying Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Valuation and qualifying accounts [Roll Forward]
Balance at beginning of period	$ 25.4	$ 25.0	$ 24.1
Charged to costs and expenses	(0.3)	0.6	0.2
Deductions	(5.5)	(0.2)	0.7
Balance at end of period	19.6	25.4	25.0
Deferred Tax Asset Valuation Allowance [Member]
Valuation and qualifying accounts [Roll Forward]
Balance at beginning of period	24.9	24.3	23.4
Charged to costs and expenses	(0.2)	0.8	0.4
Deductions	(5.4)	(0.2)	0.5
Balance at end of period	19.3	24.9	24.3
Allowance for Doubtful Accounts Receivable [Member]
Valuation and qualifying accounts [Roll Forward]
Balance at beginning of period	0.5	0.7	0.7
Charged to costs and expenses	(0.1)	(0.2)	(0.2)
Deductions	(0.1)		0.2
Balance at end of period	$ 0.3	$ 0.5	$ 0.7