Income Taxes Income Taxes - Unrecognized Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of unrecognized tax benefits [Roll Forward]
Balance at January 1	$ 88.8	$ 63.9
Additions based on tax positions related to the current year	0.5	26.7
Additions for tax positions of prior years	2.8	0
Reductions for tax positions of prior years	(15.8)	(1.5)
Settlements	(40.0)	2.4
Lapse of statutes	(1.4)	(2.7)
Balance at December 31	$ 34.9	$ 88.8