Derivative Instruments - Schedule of Fair Value Hedging Instruments Recognized in Income (Details) - Derivatives in fair value hedging relationships: - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ 24	$ (10)	$ (2)
Interest rate swaps \| Location of Gain / (Loss) Recognized in the Consolidated Income Statements: us-gaap:InvestmentIncomeInterest
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	3	29	4
Cross currency swaps \| Location of Gain / (Loss) Recognized in the Consolidated Income Statements: us-gaap:InvestmentIncomeInterest
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	15	16	2
Cross currency swaps \| Location of Gain / (Loss) Recognized in the Consolidated Income Statements: us-gaap:OtherOperatingIncomeExpenseNet
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ 6	$ (55)	$ (8)