Commodity and Other Repurchase Agreements and Collateralized Transactions Schedule of Gross Collateralized Financings by Maturity (Tables)

6 Months Ended

Mar. 31, 2020

Assets Sold under Agreements to Repurchase [Line Items]

Schedule of Repurchase Agreement Counterparties with Whom Repurchase Agreements Exceed 10 Percent of Stockholders' Equity [Table Text Block]

	March 31, 2020
	Overnight and Open		Less than 30 Days		30-90 Days		Over 90 Days		Total
Securities sold under agreements to repurchase	$	1,535.1	$	737.2	$	483.0	$	45.0	$	2,800.3
Securities loaned	1,068.8		—		—		—		1,068.8
Gross amount of secured financing	$	2,603.9	$	737.2	$	483.0	$	45.0	$	3,869.1

	September 30, 2019
	Overnight and Open		Less than 30 Days		30-90 Days		Over 90 Days		Total
Securities sold under agreements to repurchase	$	1,553.9	$	565.8	$	654.0	$	—	$	2,773.7
Securities loaned	1,459.9		—		—		—		1,459.9
Gross amount of secured financing	$	3,013.8	$	565.8	$	654.0	$	—	$	4,233.6