Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Income tax
Estimated effective income tax rate (as a percent)	(12.00%)	(12.00%)	(1.00%)	(12.00%)	(1.00%)
Income tax expense (benefit) for discrete items		$ 1.5	$ 3.2
Deferred tax position						0
Net operating loss and capital carryforwards	70.9	70.9
Tax credit carryforwards	22.8	22.8
Minimum
Income tax
Operating loss carryforwards expiration date		2012
Tax credit carryforwards, expiration date		Sep. 30, 2014
Reasonably possible unrecognized income tax benefits released within next 12 months	1.5	1.5
Maximum
Income tax
Operating loss carryforwards expiration date		2032
Tax credit carryforwards, expiration date		Sep. 30, 2032
Reasonably possible unrecognized income tax benefits released within next 12 months	$ 3.0	$ 3.0