Risk Management Activities and Fair Value Measurements - Notional Amounts And Fair Values Of Qualifying And Non-Qualifying Financial Instruments Used In Hedging Transactions (Details) - USD ($) $ in Millions	Mar. 31, 2026	Jun. 30, 2025
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	$ 19,348	$ 18,730
Fair Value Asset	88	19
Fair Value (Liability)	(568)	(1,062)
Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	15,122	15,154
Fair Value Asset	80	0
Fair Value (Liability)	(551)	(1,061)
Interest rate contracts \| Fair Value Hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	5,262	3,280
Fair Value Asset	0	0
Fair Value (Liability)	(230)	(201)
Foreign currency interest rate contracts \| Not Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	4,226	3,576
Fair Value Asset	8	19
Fair Value (Liability)	(17)	0
Foreign currency interest rate contracts \| Net Investment Hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	9,860	11,874
Fair Value Asset	80	0
Fair Value (Liability)	$ (321)	$ (860)

Risk Management Activities and Fair Value Measurements - Notional Amounts And Fair Values Of Qualifying And Non-Qualifying Financial Instruments Used In Hedging Transactions (Details) - USD ($)
$ in Millions

Mar. 31, 2026

Jun. 30, 2025

Derivative Instruments and Hedging Activities Disclosures [Line Items]

Notional Amount

$ 19,348

$ 18,730

Fair Value Asset

Fair Value (Liability)

(568)

(1,062)

Designated as Hedging Instrument

Derivative Instruments and Hedging Activities Disclosures [Line Items]