Pension and Other Postretirement Benefits - Schedule of Funded and Unfunded Pension Plans (Details) - USD ($) $ in Millions	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Defined Benefit Plan Disclosure [Line Items]
Grantor Trust assets	$ 262	$ 265
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	1,146	1,155	$ 1,119
Accumulated benefit obligation	1,050	1,050
Fair value of plan assets	921	904	$ 891
Grantor Trust assets	262	265
Funded plans | Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	895	894
Accumulated benefit obligation	806	794
Fair value of plan assets	921	904
Unfunded plans | Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	251	261
Accumulated benefit obligation	245	256
Fair value of plan assets	$ 0	$ 0