Schedule II (Details) (Allowance for Doubtful Accounts [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for doubtful accounts, Balance at beginning of period	$ 0	$ 0.1	$ 0.1
Allowance for doubtful accounts, Charged to Cost and Expense	0	0	0
Allowance for doubtful accounts, Other Additions	0	0	0
Allowance for doubtful accounts, Deductions (write-offs)	0	(0.1)	0
Allowance for doubtful accounts, Balance at end of period	$ 0	$ 0	$ 0.1