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, 2024	Jun. 30, 2023
Change in the fair value of plan assets for the Company’s benefit plans:
Grantor Trust assets	$ 266	$ 276
Pension benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, beginning of the year	1,172	1,203
Service cost	27	30
Interest cost	61	52
Benefits paid	(43)	(22)
Settlements	(50)	(32)
Actuarial gains	(48)	(58)
Other	0	(1)
Projected benefit obligation, end of the year	1,119	1,172
Change in the fair value of plan assets for the Company’s benefit plans:
Fair value of plan assets, beginning of the year	853	801
Actual return on plan assets	45	53
Employer contributions	86	53
Benefits paid	(43)	(22)
Settlements	(50)	(32)
Fair value of plan assets, end of the year	891	853
Funded status	(228)	(319)
Grantor Trust assets	266	276
Postretirement benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, beginning of the year	47	53
Service cost	0	1
Interest cost	2	2
Benefits paid	(3)	(4)
Settlements	0	0
Actuarial gains	(1)	(5)
Other	0	0
Projected benefit obligation, end of the year	45	47
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	3	4
Benefits paid	(3)	(4)
Settlements	0	0
Fair value of plan assets, end of the year	0	0
Funded status	(45)	(47)
Grantor Trust assets	$ 0	$ 0