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

6 Months Ended

Mar. 31, 2018

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, 2018
	Overnight and Open		Less than 30 Days		30-90 Days		Over 90 Days		Total
Securities sold under agreements to repurchase	$	797.7	$	464.3	$	280.5	$	20.0	$	1,562.5
Securities loaned	559.1		—		—		—		559.1
Gross amount of secured financing	$	1,356.8	$	464.3	$	280.5	$	20.0	$	2,121.6

	September 30, 2017
	Overnight and Open		Less than 30 Days		30-90 Days		Over 90 Days		Total
Securities sold under agreements to repurchase	$	640.2	$	432.9	$	320.0	$	—	$	1,393.1
Securities loaned	111.1		—		—		—		111.1
Gross amount of secured financing	$	751.3	$	432.9	$	320.0	$	—	$	1,504.2