Condensed Consolidated Cash Flows Statements - USD ($)	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 18.2	$ (6.9)
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	2.9	2.7
Bad debts	0.3	0.1
(Recovery) bad debt on physical coal	(2.4)	1.0
Deferred Income Tax Expense (Benefit)	0	19.7
Amortization of debt issuance costs and debt discount	0.2	0.3
Amortization of stock-based compensation	1.9	1.6
Loss on sale of property and equipment	0	(0.6)
Changes in operating assets and liabilities, net:
Cash, securities and other assets segregated under federal and other regulations	330.3	7.6
Securities purchased under agreements to resell	(320.5)	(153)
Increase (Decrease) in Securities Borrowed	(737.9)	(9)
Deposits with and receivables from broker-dealers, clearing organizations, and counterparties	(225.5)	3.5
Receivables from customers, net	(63.7)	(54)
Notes receivable, net	2.2	0
Income taxes receivable	0.1	(0.4)
Financial instruments owned, at fair value	0.3	(292)
Physical commodities inventory	0	(121)
Other assets	(6.1)	(2.5)
Accounts payable and other accrued liabilities	(15.7)	(20.4)
Payables to customers	(361.2)	26.7
Payables to broker-dealers, clearing organizations and counterparties	133.6	69.6
Income taxes payable	1	0.9
Payables under repurchase agreements	302.6	257.4
Increase (Decrease) in Securities Loaned Transactions	753.1	(2.3)
Financial instruments sold, not yet purchased, at fair value	(26.7)	86.1
Net cash used in operation activities	(213)	(184.9)
Cash flows from investing activities:
Cash paid for acquisitions, net	0.7	0
Purchase of property and equipment	4.5	3.2
Net cash used in investing activities	(5.2)	(3.2)
Cash flows from financing activities:
Net change in payable to lenders under loans	80.4	192.9
Payments of note payable	0.2	0.2
Deferred payments on acquisitions	0	2.3
Debt issuance costs	0.9	0.1
Exercise of stock options	0.3	1.5
Withholding taxes on stock option exercises	0	(0.8)
Net cash provided by financing activities	79.6	191
Effect of exchange rates on cash and cash equivalents	0.3	5.1
Net (decrease) increase in cash and cash equivalents	(138.3)	8
Cash and cash equivalents	358.2	321.8
Supplemental disclosure of cash flow information:
Cash paid for interest	33.7	11.3
Income taxes paid, net of cash refunds	5.3	5.3
Acquisition of business:
Cash, segregated cash, cash equivalents, and segregated cash equivalents at beginning of period	2,051.8	2,609.4
Assets acquired	3.1	0
Liabilities assumed	(0.9)	0
Total net assets acquired	$ 2.2	$ 0