Pension and Other Postretirement Benefits - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plans, employer contribution	$ 78	$ 74	$ 70
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 1,050	$ 1,050
Pension Benefits | Return Seeking Assets
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation (as percent)	32.00%
Pension Benefits | Liability Hedging Assets
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation (as percent)	68.00%