Recently Issued Accounting Standards (Details) (USD $) In Millions	Sep. 30, 2010	Jun. 30, 2011 Accounts Receivable [Member]	Jun. 30, 2011 Notes Payable To Banks [Member]	Jun. 30, 2011 Short-Term Investments [Member]
Outstanding balance on receivables		$ 217.9	$ 135.0
Investment in Ralcorp Receivables Corporation	$ 137.8			$ 0