Income Taxes (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Change in unrecognized tax benefits
Beginning balance	$ 36.8	$ 40.1	$ 32.9
Additions for tax positions related to the current year	3.8	3.3	5.8
Additions for tax positions of prior years	16.4	9.3	7.5
Reductions for tax positions of prior years	(0.1)	(5.6)	(4.5)
Settlements	(3.5)	(9.5)	(1.5)
Expiration of statute of limitations	(0.9)	(0.8)	(0.1)
Ending balance	$ 52.5	$ 36.8	$ 40.1