Consolidated Cash Flows Statements (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Cash flows from operating activities:
Net income	$ 14.9	$ 37.2	$ 5.1
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	7.2	4.7	1.7
Provision for bad debts and impairments	1.7	6.2	3.5
Deferred income taxes	(0.3)	1.8	3.7
Amortization of debt issuance costs and debt discount	1.7	1.6	0.2
Convertible debt interest settled in company stock upon conversion	0	0.2	0
Amortization of stock-based compensation expense	5.9	2.3	1.9
Extraordinary loss on acquisition of FCStone	0	0	7.0
Impairment of INTL Sieramet	0	0	1.1
Deconsolidation and impairment of Agora-X subsidiary	0	0	(2.9)
Gain on acquisition of INTL Provident	0	(0.4)	0
Changes in operating assets and liabilities, net:
Cash, securities and other assets segregated under federal and other regulations	(199.9)	(104.1)	(0.3)
Deposits and receivables from exchange-clearing organizations	(97.7)	(586.0)	(4.2)
Deposits and receivables from broker-dealers, clearing organizations, and counterparties	42.7	47.1	(57.6)
Receivable from customers, net	46.4	(39.1)	(18.2)
Notes receivable, net	(77.9)	2.9	(7.0)
Income taxes receivable	(3.1)	0.6	35.4
Financial instruments owned, at fair value	58.3	280.7	(212.7)
Physical commodities inventory	29.0	(35.6)	(18.1)
Other assets	(1.6)	(12.1)	3.9
Accounts payable and other accrued liabilities	10.6	30.8	1.9
Payable to customers	248.0	366.2	415.3
Payable to broker-dealers, clearing organizations and counterparties	35.9	(0.5)	(0.4)
Income taxes payable	1.6	1.6	0.4
Financial instruments sold, not yet purchased, at fair value	(215.5)	202.9	(46.7)
Net cash (used in) provided by operating activities	(92.1)	209.0	113.0
Cash flows from investing activities:
Deconsolidation of affiliates	0.4	0	(0.3)
Disposition of affiliates	0	0	0.2
Cash paid for other acquisitions, net	(11.7)	(9.3)	(37.6)
Purchase of exchange memberships and common stock	0	(3.4)	0
Sale of exchange memberships and common stock	0	1.3	0
Purchase of property and equipment	(8.7)	(10.1)	(4.7)
Net cash used in investing activities	(20.0)	(21.5)	(42.4)
Cash flows from financing activities:
Net change in payable to lenders under loans	140.8	(37.5)	6.1
Payments related to earn-outs on acquisitions	(9.6)	(9.4)	0
Repayment of subordinated debt	0	(0.5)	(56.0)
Share repurchase	(4.0)	0	0
Debt issuance costs	(0.3)	(2.4)	0
Exercise of stock options	1.9	1.4	0.7
Income tax benefit on stock options and awards	0.2	0	0
Net cash provided by financing activities	129.0	(48.4)	(49.2)
Effect of exchange rates on cash and cash equivalents	(1.2)	(0.4)	0
Net increase (decrease) in cash and cash equivalents	15.7	138.7	21.4
Cash and cash equivalents at beginning of period	220.6	81.9	60.5
Cash and cash equivalents at end of period	236.3	220.6	81.9
Supplemental disclosure of cash flow information:
Cash paid for interest	7.9	9.5	7.4
Income taxes paid (received), net of cash refunds	6.1	17.6	(33.3)
Supplemental disclosure of non-cash investing and financing activities:
Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments	0	16.7	0
Goodwill and intangible assets acquired during the period	1.8	4.9	39.8
Additional consideration payable related to acquisitions	$ 2.1	$ 5.4	$ 26.3