Securities and Commodity Financing Transactions (Tables)

12 Months Ended

Sep. 30, 2023

Broker-Dealer [Abstract]

Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets

	September 30, 2023
	Overnight and Open		Less than 30 Days		30-90 Days		Over 90 Days		Total
Securities sold under agreements to repurchase	$	8,300.0	$	786.8	$	107.0	$	2.6	$	9,196.4
Securities loaned	1,117.3		—		—		—		1,117.3
Gross amount of secured financing	$	9,417.3	$	786.8	$	107.0	$	2.6	$	10,313.7

	September 30, 2022
	Overnight and Open		Less than 30 Days		30-90 Days		Over 90 Days		Total
Securities sold under agreements to repurchase	$	3,664.7	$	2,279.1	$	186.3	$	3.4	$	6,133.5
Securities loaned	1,189.5		—		—		—		1,189.5
Gross amount of secured financing	$	4,854.2	$	2,279.1	$	186.3	$	3.4	$	7,323.0

Schedule of Financial Instruments Owned and Pledged as Collateral

	September 30,
Securities sold under agreements to repurchase	2023		2022
U.S. Treasury obligations	$	3,696.1	$	1,311.0
U.S. government agency obligations	542.2		604.1
Asset-backed obligations	102.9		178.0
Agency mortgage-backed obligations	4,371.6		3,762.5
Foreign government obligations	148.1		97.2
Corporate bonds	335.5		180.7
Total securities sold under agreement to repurchase	$	9,196.4	$	6,133.5
Securities loaned
Equity securities	$	1,117.3	$	1,189.5
Total securities loaned	1,117.3		1,189.5
Gross amount of secured financing	$	10,313.7	$	7,323.0

The following tables provide the netting of securities purchased under agreements to resell, securities sold under agreements to repurchase, securities borrowed and securities loaned as of the periods indicated (in millions):

	September 30, 2023
Offsetting of collateralized transactions:	Gross Amounts Recognized		Amounts Offset in the Consolidated Balance Sheet		Net Amounts Presented in the Consolidated Balance Sheet
Securities purchased under agreements to resell	$	7,649.3	$	(4,669.8)	$	2,979.5
Securities borrowed	$	1,129.1	$	—	$	1,129.1
Securities sold under agreements to repurchase	$	9,196.4	$	(4,669.8)	$	4,526.6
Securities loaned	$	1,117.3	$	—	$	1,117.3

	September 30, 2022
Offsetting of collateralized transactions:	Gross Amounts Recognized		Amounts Offset in the Consolidated Balance Sheet		Net Amounts Presented in the Consolidated Balance Sheet
Securities purchased under agreements to resell	$	4,609.9	$	(2,937.9)	$	1,672.0
Securities borrowed	$	1,209.8	$	—	$	1,209.8
Securities sold under agreements to repurchase	$	6,133.5	$	(2,937.9)	$	3,195.6
Securities loaned	$	1,189.5	$	—	$	1,189.5

Schedule of Carrying Value of Collateral Pledged, Received and Repledged

The following table sets forth the carrying value, which approximates fair value because of its short term nature, of collateral pledged, received and repledged (in millions):

	September 30, 2023		September 30, 2022
Securities pledged or repledged to cover collateral requirements for tri-party arrangements	$	4,726.6	$	3,787.8
Securities received as collateral that may be repledged	$	9,180.1	$	5,836.1
Securities received as collateral that may be repledged covering securities sold short	$	2,461.1	$	1,615.3
Repledged securities borrowed and client securities held under custodial clearing arrangements to collateralize securities loaned agreements	$	1,097.3	$	1,146.0