RETIREMENT BENEFIT OBLIGATIONS - Schedule of Allocation of Plan Assets (Details) - USD ($) $ in Millions	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 873	$ 911	$ 886
NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	286	304
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	16
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	570	585
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	6
Domestic equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26	35
Domestic equity funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26	35
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	16	39
International equity funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16	20
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	19
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	132	111
Domestic fixed income funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	132	111
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	607	652
International fixed income funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	94	119
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	513	533
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	29	28
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	29	28
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	63	46
Other | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18	19
Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	16
Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28	5
Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 6	$ 6