Pension and Other Postretirement Benefits - Schedule of Amounts Recognized in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	Jun. 30, 2026	Jun. 30, 2025
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial losses (gains)	$ 169	$ 196
Prior service cost	3	1
Net amounts recognized	172	197
Postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial losses (gains)	(27)	(27)
Prior service cost	0	0
Net amounts recognized	$ (27)	$ (27)