Retirement Benefit Obligations - Schedule of Allocation of Plan Assets (Detail) - USD ($) $ in Millions	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,051	$ 1,447	$ 1,319
NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	945	1,317
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	53	53
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46	67
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	10	$ 9
Domestic equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	37	61
Domestic equity funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	37	61
Domestic equity funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Domestic equity funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Domestic equity funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	112	199
International equity funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	112	199
International equity funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International equity funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International equity funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Domestic fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	106	144
Domestic fixed income funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	106	144
Domestic fixed income funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Domestic fixed income funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Domestic fixed income funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	666	882
International fixed income funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	666	882
International fixed income funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International fixed income funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International fixed income funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Balanced funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46	67
Balanced funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Balanced funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Balanced funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46	67
Balanced funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	84	94
Other | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24	31
Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	53	53
Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 7	$ 10