Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Mar. 31, 2012	Mar. 31, 2012
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Estimated effective income tax rate	27.40%	30.90%
U.S. Federal statutory rate		35.00%
Income Tax Uncertainties [Abstract]
Gross unrecognized tax benefits	$ 25.7	$ 25.7
Gross urecognized tax benefits, if recognized, would affect effective tax rate	16.6	16.6
Gross interest and penatlites accrued	1.3	1.3
Possible reduction in unrecognized tax benefits, lower bound	(0.3)	(0.3)
Possible reduction in unrecognized tax benefits, upper bound	(1.1)	(1.1)
Components of Deferred Tax Assets [Abstract]
Deferred tax assets before valuation allowance	64.6	64.6
Valuation allowance	$ 10.4	$ 10.4