Income Tax Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Income Tax Expense [Abstract]
Effective income tax rate	28.00%	35.30%	33.80%	35.00%
Decrease in effective tax rate	9.60%		4.20%
Impact on income tax expense by net research tax credits				$ 0.4
Decrease in effective tax rate				0.80%
Estimated annual effective income tax rate			35.00%
Reduction of unrecognized tax benefits	$ 1.8		$ 1.8