Retirement Benefits - Schedule of Fair Value Measurement of Plan Assets Using Significant Unobservable Inputs (Details) - Level 3 - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets at beginning of year	$ 0	$ 0
Actual return on plan assets still held at year-end	12	0
Purchases, sales, settlements - net	203	0
Transfers into Level 3	325	0
Changes due to exchange rates	43	0
Fair value of plan assets at end of year	$ 583	$ 0