Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Effective tax rates	35.80%	33.30%	40.60%	36.90%
Discrete benefit		$ 3.5
Unrecognized tax benefits					28.1
Increase in gross unrecognized tax benefits			1.1
Reduction in provision for income taxes due to impact of effective tax rate	23.0		23.0
Gross interest and penalties accrued	2.8		2.8
Deferred Tax Assets, Net, Current	8.4		8.4		10.0
Deferred Tax Assets, Net, Noncurrent	55.7		55.7		28.3
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	$ 0.1	$ 11.6	$ 4.2	$ 45.0