Retirement Benefits - Schedule of Fair Values of Pension Plan Assets by Asset Class (Details) - USD ($) $ in Millions	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Defined Benefit Plan Disclosure [Line Items]
(Payables) receivables, net	$ (112)	$ (89)
Total	5,622	5,646
Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	5,734	5,735
Fair Value, Inputs, Level 1, 2 and 3 \| Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	549	540
Fair Value, Inputs, Level 1, 2 and 3 \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	2	7
Fair Value, Inputs, Level 1, 2 and 3 \| Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	39	57
Fair Value, Inputs, Level 1, 2 and 3 \| Commingled equity funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	793	1,059
Fair Value, Inputs, Level 1, 2 and 3 \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	1,059	801
Fair Value, Inputs, Level 1, 2 and 3 \| Government issued securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	477	552
Fair Value, Inputs, Level 1, 2 and 3 \| Commingled fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	1,527	1,293
Fair Value, Inputs, Level 1, 2 and 3 \| Alternatives
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	708	778
Fair Value, Inputs, Level 1, 2 and 3 \| Other
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	580	648
Level 1
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	1,044	1,114
Level 1 \| Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	523	459
Level 1 \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	2	7
Level 1 \| Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	39	57
Level 1 \| Commingled equity funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 1 \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	23	4
Level 1 \| Government issued securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	422	521
Level 1 \| Commingled fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 1 \| Alternatives
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 1 \| Other
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	35	66
Level 2
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	1,628	1,359
Level 2 \| Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	26	76
Level 2 \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 2 \| Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 2 \| Commingled equity funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	61	106
Level 2 \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	1,036	797
Level 2 \| Government issued securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	55	31
Level 2 \| Commingled fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	446	350
Level 2 \| Alternatives
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 2 \| Other
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	4	(1)
Level 3
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	541	583	$ 0
Level 3 \| Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 3 \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 3 \| Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 3 \| Commingled equity funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 3 \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 3 \| Government issued securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0
Level 3 \| Commingled fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 3 \| Alternatives
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0
Level 3 \| Other
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	541	583
NAV
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	2,521	2,679
NAV \| Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	5
NAV \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
NAV \| Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
NAV \| Commingled equity funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	732	953
NAV \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
NAV \| Government issued securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0
NAV \| Commingled fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	1,081	943
NAV \| Alternatives
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	708	778
NAV \| Other
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	$ 0	$ 0