Consolidated Cash Flows Statements - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 55.7	$ 19.3	$ 19.3
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	7.2	7.3	8.0
Provision for bad debts and impairments	7.3	5.5	0.8
Deferred income taxes	4.8	(6.8)	(7.8)
Amortization of debt issuance costs and debt discount	0.9	1.0	1.2
Amortization of share-based compensation expense	3.6	4.3	9.3
Loss on sale of property and equipment	0.5	0.3	(0.4)
Gain on disposal of affiliate	0.0	0.0	(0.4)
Gain on sale of exchange memberships and common stock	(1.2)	0.0	(9.1)
Changes in operating assets and liabilities, net:
Cash, securities and other assets segregated under federal and other regulations	(315.0)	(1.3)	(95.1)
Change in securities purchased under agreements to resell	15.2	0.0	0.0
Deposits and receivables from exchange-clearing organizations	195.1	(159.2)	42.3
Deposits and receivables from broker-dealers, clearing organizations, and counterparties	(150.2)	1.1	(53.4)
Receivable from customers, net	(169.0)	32.0	(23.7)
Notes receivable, net	(14.5)	(27.9)	66.6
Income taxes receivable	0.0	4.2	(0.2)
Financial instruments owned, at fair value	(565.0)	(42.6)	3.1
Physical commodities inventory	7.1	17.8	72.7
Other assets	(16.2)	0.1	4.3
Accounts payable and other accrued liabilities	23.2	1.9	(0.2)
Payable to customers	332.1	191.5	24.0
Payable to broker-dealers, clearing organizations and counterparties	251.1	(5.2)	(22.3)
Income taxes payable	1.7	5.2	0.5
Change in securities sold under agreements to repurchase	186.0	0.0	0.0
Financial instruments sold, not yet purchased, at fair value	177.5	84.1	4.6
Net cash provided by operating activities	37.9	132.6	44.9
Cash flows from investing activities:
Disposal and deconsolidation of affiliates	0.0	0.0	0.2
Cash paid for acquisitions, net	(7.8)	0.0	0.0
Purchase of exchange memberships and common stock	(0.7)	0.0	(0.3)
Sale of exchange memberships and common stock	2.1	0.0	10.1
Purchase of property and equipment	(9.1)	(4.3)	(4.9)
Net cash (used in) provided by investing activities	(15.5)	(4.3)	5.1
Cash flows from financing activities:
Net change in payable to lenders under loans	15.5	(38.5)	(157.2)
Payments related to earn-outs on acquisitions	(2.2)	(1.6)	(12.0)
Proceeds from issuance of senior unsecured notes	0.0	0.0	45.5
Proceeds from notes payable	4.0	0.0	0.0
Repayment of note payable	0.4	0.0	0.0
Share repurchase	(4.7)	(9.7)	(3.9)
Debt issuance costs	(0.2)	(0.3)	(3.7)
Exercise of stock options	2.5	1.4	1.5
Income tax benefit on stock options and awards	0.5	(0.1)	0.1
Net cash provided by (used in) financing activities	15.0	(48.8)	(129.7)
Effect of exchange rates on cash and cash equivalents	(0.6)	(4.3)	(0.5)
Net increase (decrease) in cash and cash equivalents	36.8	75.2	(80.2)
Cash and cash equivalents at beginning of period	231.3	156.1	236.3
Cash and cash equivalents at end of period	268.1	231.3	156.1
Supplemental disclosure of cash flow information:
Cash paid for interest	15.8	9.6	8.9
Income taxes paid, net of cash refunds	15.3	3.0	10.2
Supplemental disclosure of non-cash investing and financing activities:
Identified intangible assets and goodwill on acquisitions	1.6	0.5	5.6
Additional consideration payable related to acquisitions	1.9	(1.8)	8.2
Acquisition of business, value of assets acquired	1,011.4	0.0	0.0
Acquisition of business, value of liabilities assumed	(995.1)	0.0	0.0
Acquisition of business, net nonmonetary assets acquired (liabilities assumed)	16.3	0.0	0.0
Deferred consideration payable related to acquisitions	5.0	0.0	0.0
Escrow deposits related to acquisitions	$ 5.0	$ 0.0	$ 0.0