Pension and Other Postretirement Benefits - Schedule of Amounts Recognized in Balance Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2026	Jun. 30, 2025
Defined Benefit Plan Disclosure [Line Items]
Net amounts recognized	$ 266
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Pension assets	26	$ 10
Accrued pension liabilities	(251)	(261)
Net amounts recognized	(225)	(251)
Postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Pension assets	0	0
Accrued pension liabilities	(41)	(44)
Net amounts recognized	$ (41)	$ (44)