Commodity and Other Repurchase Agreements Fair Value of Securities Accepted or Pledged as Collateral (Details) - USD ($)	Sep. 30, 2019	Sep. 30, 2018
Revenues from contracts with customers [Abstract]
Fair Value of Securities Received as Collateral that Can be Resold or Repledged	$ 3,060,200,000
Financial Instruments Owned and Pledged as Collateral, Amount Eligible to be Repledged by Counterparty	478,800,000
Financial Instruments Owned and Pledged as Collateral, Amount Not Eligible to be Repledged by Counterparty	1,228,900,000
Pledged Assets Separately Reported, Securities Pledged for Repurchase Agreements, at Fair Value	1,175,100,000
Securities Loaned, Fair Value of Collateral	1,414,000,000.0
Fair Value of Securities Received as Collateral that Have Been Resold or Repledged	329,800,000
Pledged Financial Instruments, Not Separately Reported, Securities	$ 0	$ 27,100,000

Revenues from contracts with customers [Abstract]

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- Definition

Fair value of collateral permitted, by contact or custom, to be sold or re-pledged.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

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- Definition

Fair value of the collateral, or portion thereof, that has been re-pledged, delivered, or otherwise used.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
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-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

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- Definition

Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions where counterparty has the right to re-pledge such.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
-Section 50
-Paragraph 1A
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- Definition

The fair value, as of the date of each statement of financial position presented, of securities which are owned but transferred to serve as collateral for the payment of repurchase agreements, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

+ References

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- Definition

Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
-Section 50
-Paragraph 1A
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- Definition

Fair value of the securities pledged as collateral against securities loaned.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226013-175313

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