Income Taxes - Unrecognized Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
Unrecognized tax benefits that would impact effective tax rate	$ 22.6
Reconciliation of the total gross unrecognized tax benefits
Balance, January 1	27.6	34.8
Additions based on tax positions related to current year	0.5	1.1
Additions (reductions) for tax positions of prior years	3.9	0.3
Reductions for lapse in statute of limitations	(0.8)	(1.3)
Settlements	(4.3)	(6.6)
Translation adjustment	(0.7)	(0.7)
Balance, December 31	26.2	27.6
Income tax penalties and interest expense	1.7	2.5
Income tax penalties and interest accrued on unrecognized tax benefits	$ 7.8	$ 6.3