Investment Securities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
May 31, 2023	May 31, 2022	May 31, 2021
Investments, Debt and Equity Securities [Abstract]
Debt securities, trading, unrealized gain (loss)	$ (3)	$ (27)	$ (3)
Proceeds from sale of debt securities	36	5	6
Debt securities, trading, realized gain (less than $0.1 million for the year ended May 31, 2023 and 2022)	1	1
Debt securities, trading, realized loss (less than $0.1 million for the year ended May 31, 2021)			1
Equity securities, unrealized gain	$ 2		$ 4
Investment securities losses		$ 1

Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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- Definition

Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in net income (trading).

+ References

+ Details

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- Definition

Amount of unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in net income (trading).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-14

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

+ Details

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- Definition

Amount of unrealized gain on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 321
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479536/321-10-50-4

+ Details

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- Definition

Amount of unrealized loss on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

+ Details

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- References

No definition available.

+ Details

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- Definition

The cash inflow associated with the sale of securities classified as trading securities and held for investment purposes. Excludes proceeds from trading securities purchased and held principally for the purpose of selling them in the near term (thus held for only a short period of time).

+ References

No definition available.

+ Details

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