Condensed Consolidated Balance Sheets (Parenthetical) (Parentheticals) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2012	Sep. 30, 2011
Securities and other assets segregated, fair value	$ 72.8	$ 22.7
Dep and rec -exch clear org - fair value	1,288.1	1,408.2
Receivables from Brokers-Dealers and Clearing Organizations	1.0	16.2
Accounts Payable and Other Accrued Liabilities	$ 20.7	$ 22.3
Preferred stock - par value	$ 0.01	$ 0.01
Preferred stock - authorized	1,000,000	1,000,000
Preferred stock - issued	0	0
Preferred stock - outstanding	0	0
Common stock - par value	$ 0.01	$ 0.01
Common stock - authorized	30,000,000	30,000,000
Common stock - issued	19,166,799	18,653,964
Common stock - outstanding	19,005,242	18,642,407
Treasury stock - shares	161,557	11,557