Pension and Other Postretirement Benefits - Schedule of Projected Benefit Obligation, Changes in Fair Value of Plan Assets and Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2026	Jun. 30, 2025
Change in the fair value of plan assets for the Company’s benefit plans:
Grantor Trust assets	$ 262	$ 265
Pension benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, beginning of the year	1,155	1,119
Service cost	23	23
Interest cost	55	57
Benefits paid	(44)	(44)
Settlements	(41)	(37)
Actuarial (gains) losses	(5)	37
Plan amendments	3	0
Projected benefit obligation, end of the year	1,146	1,155
Change in the fair value of plan assets for the Company’s benefit plans:
Fair value of plan assets, beginning of the year	904	891
Actual return on plan assets	66	54
Employer contributions	36	40
Benefits paid	(44)	(44)
Settlements	(41)	(37)
Fair value of plan assets, end of the year	921	904
Funded status	(225)	(251)
Grantor Trust assets	262	265
Postretirement benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, beginning of the year	44	45
Service cost	0	1
Interest cost	2	2
Benefits paid	(2)	(3)
Settlements	0	0
Actuarial (gains) losses	(3)	(1)
Plan amendments	0	0
Projected benefit obligation, end of the year	41	44
Change in the fair value of plan assets for the Company’s benefit plans:
Fair value of plan assets, beginning of the year	0	0
Actual return on plan assets	0	0
Employer contributions	2	3
Benefits paid	(2)	(3)
Settlements	0	0
Fair value of plan assets, end of the year	0	0
Funded status	(41)	(44)
Grantor Trust assets	$ 0	$ 0