Income Taxes (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of the beginning and ending of unrecognized tax benefits
Balance at January 1	$ 64.4	$ 121.5	$ 147.1
Additions based on tax positions related to the current period	13.0	2.2	3.6
Additions for tax positions of prior periods	69.8	48.6	13.3
Reductions for tax positions of prior periods	(18.6)	(75.8)	(18.5)
Statute expirations	(1.9)	(2.3)	(3.7)
Settlements	(0.8)	(29.8)	(20.3)
Balance at December 31	$ 125.9	$ 64.4	$ 121.5