Income Taxes (Details 1) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Change in unrecognized tax benefits
Beginning balance	$ 52.5	$ 36.8
Additions for tax positions related to the current year	2.0	1.8
Additions for tax positions of prior years		14.5
Reductions for tax positions of prior years	(1.1)
Settlements	(3.3)	(0.7)
Expiration of statute of limitations	(0.1)	(0.1)
Ending balance	$ 50.0	$ 52.3