Assets and Liabilities, at Fair Value (Tables)

12 Months Ended

Sep. 30, 2019

Assets and Liabilities, at Fair Value [Abstract]

Fair Value, Assets Measured on Recurring Basis [Table Text Block]

The following tables set forth the Company’s financial and nonfinancial assets and liabilities accounted for at fair value, on a recurring basis, as of September 30, 2019 and September 30, 2018 by level in the fair value hierarchy. Except as disclosed in Note 7, there were no assets or liabilities that were measured at fair value on a nonrecurring basis as of September 30, 2019 and 2018.

	September 30, 2019
(in millions)	Level 1		Level 2		Level 3		Netting (1)			Total
Assets:
Certificates of deposit	$	4.9	$	—	$	—	$	—		$	4.9
Money market mutual funds	8.9		—		—		—			8.9
Cash and cash equivalents	13.8		—		—		—			13.8
Commodities warehouse receipts	6.2		—		—		—			6.2
U.S. Treasury obligations	299.8		—		—		—			299.8
Securities and other assets segregated under federal and other regulations	306.0		—		—		—			306.0
U.S. Treasury obligations	593.9		—		—		—			593.9
"To be announced" (TBA) and forward settling securities	—		9.8		—		(1.5		)	8.3
Foreign government obligations	9.9		—		—		—			9.9
Derivatives	3,131.2		43.2		—		(3,159.6		)	14.8
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	3,735.0		53.0		—		(3,161.1		)	626.9
Equity securities	159.5		9.0		—		—			168.5
Corporate and municipal bonds	—		80.0		—		—			80.0
U.S. Treasury obligations	248.7		—		—		—			248.7
U.S. government agency obligations	—		447.1		—		—			447.1
Foreign government obligations	0.5		—		—		—			0.5
Agency mortgage-backed obligations	—		1,045.0		—		—			1,045.0
Asset-backed obligations	—		29.1		—		—			29.1
Derivatives	1.0		486.3		—		(420.8		)	66.5
Commodities leases	—		28.6		—		—			28.6
Commodities warehouse receipts	48.4		—		—		—			48.4
Exchange firm common stock	12.7		—		—		—			12.7
Mutual funds and other	0.1		—		—		—			0.1
Financial instruments owned	470.9		2,125.1		—		(420.8		)	2,175.2
Physical commodities inventory	7.1		144.8		—		—			151.9
Total assets at fair value	$	4,532.8	$	2,322.9	$	—	$	(3,581.9	)	$	3,273.8
Liabilities:
Accounts payable and other accrued liabilities - contingent liabilities	$	—	$	—	$	1.8	$	—		$	1.8
TBA and forward settling securities	—		6.8		—		(1.5		)	5.3
Derivatives	3,079.1		38.3		—		(3,117.1		)	0.3
Payable to broker-dealers, clearing organizations and counterparties	3,079.1		45.1		—		(3,118.6		)	5.6
Equity securities	147.3		10.8		—		—			158.1
Foreign government obligations	—		—		—		—			—
Corporate and municipal bonds	—		39.2		—		—			39.2
U.S. Treasury obligations	272.3		—		—		—			272.3
U.S. government agency obligations	—		43.8		—		—			43.8
Agency mortgage-backed obligations	—		29.6		—		—			29.6
Derivatives			480.3		—		(422.2		)	58.1
Commodities leases	$	—	$	113.7	$	—	$	—		$	113.7
Financial instruments sold, not yet purchased	419.6		717.4		—		(422.2		)	714.8
Total liabilities at fair value	$	3,498.7	$	762.5	$	1.8	$	(3,540.8	)	$	722.2

(1) Represents cash collateral and the impact of netting across the levels of the fair value hierarchy. Netting among positions classified within the same level are included in that level.

	September 30, 2018
(in millions)	Level 1		Level 2		Level 3		Netting (1)			Total
Assets:
Cash and cash equivalents - certificaes of deposit	$	3.8	$	—	$	—	$	—		$	3.8
Commodities warehouse receipts	42.9		—		—		—			42.9
U.S. Treasury obligations	600.4		—		—		—			600.4
Securities and other assets segregated under federal and other regulations	643.3		—		—		—			643.3
U.S. Treasury obligations	778.4		—		—		—			778.4
TBA and forward settling securities	—		5.0		—		(2.1		)	2.9
Foreign government obligations	7.7		—		—		—			7.7
Derivatives	7,495.9		19.6		—		(7,787.1		)	(271.6		)
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	8,282.0		24.6		—		(7,789.2		)	517.4
Equity securities	71.2		3.0		—		—			74.2
Corporate and municipal bonds	—		79.1		—		—			79.1
U.S. Treasury obligations	120.1		—		—		—			120.1
U.S. government agency obligations	—		472.9		—		—			472.9
Foreign government obligations	6.4		—		—		—			6.4
Agency mortgage-backed obligations	—		1,022.5		—		—			1,022.5
Asset-backed obligations	—		42.9		—		—			42.9
Derivatives	0.8		514.6		—		(329.3		)	186.1
Commodities leases	—		29.5		—		(11.8		)	17.7
Commodities warehouse receipts	16.4		—		—		—			16.4
Exchange firm common stock	10.2		—		—		—			10.2
Mutual funds and other	6.3		—		—		—			6.3
Financial instruments owned	231.4		2,164.5		—		(341.1		)	2,054.8
Physical commodities inventory	42.1		114.8		—		—			156.9
Total assets at fair value	$	9,202.6	$	2,303.9	$	—	$	(8,130.3	)	$	3,376.2
Liabilities:
TBA and forward settling securities	$	—	$	2.1	$	—	$	(2.1	)	$	—
Derivatives	7,809.3		11.6		—		(7,820.9		)	—
Payable to broker-dealers, clearing organizations and counterparties	7,809.3		13.7		—		(7,823.0		)	—
Equity securities	51.1		0.4		—		—			51.5
Corporate and municipal bonds	—		20.1		—		—			20.1
U.S. Treasury obligations	484.8		—		—		—			484.8
U.S. government agency obligations	—		57.2		—		—			57.2
Agency mortgage-backed obligations	—		0.2		—		—			0.2
Derivatives			688.0		—		(494.6		)	193.4
Commodities leases	—		75.5		—		(16.2		)	59.3
Financial instruments sold, not yet purchased	535.9		841.4		—		(510.8		)	866.5
Total liabilities at fair value	$	8,345.2	$	855.1	$	—	$	(8,333.8	)	$	866.5

(1) Represents cash collateral and the impact of netting across the levels of the fair value hierarchy. Netting among positions classified within the same level are included in that level.

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

The following tables set forth a summary of changes in the fair value of the Company’s Level 3 financial assets and liabilities during the years ended September 30, 2019 and 2018, including a summary of unrealized gains (losses) during the fiscal year ended on the Company’s Level 3 financial assets and liabilities held during the periods.

	Level 3 Financial Liabilities For the Year Ended September 30, 2019
(in millions)	Balances at beginning of period		Realized (gains) losses during period		Remeasurement (gains) losses during period		Acquisitions		Settlements		Transfers in or (out) of Level 3		Balances at end of period
Liabilities:
Contingent liabilities	$	—	$	—	$	—	$	1.8	$	—	$	—	$	1.8

	Level 3 Financial Assets and Financial Liabilities For the Year Ended September 30, 2018
(in millions)	Balances at beginning of period		Realized gains (losses) during period		Unrealized gains (losses) during period			Purchases/ issuances		Settlements			Transfers in or (out) of Level 3		Balances at end of period
Assets:
Equity securities	$	0.1	$	—	$	(0.1	)	$	—	$	—		$	—	$	—
(in millions)	Balances at beginning of period		Realized (gains) losses during period		Remeasurement (gains) losses during period			Acquisitions		Settlements			Transfers in or (out) of Level 3		Balances at end of period
Liabilities:
Contingent liabilities	$	1.0	$	—	$	—		$	—	$	(1.0	)	$	—	$	—