Retirement Benefits - Schedule of Fair Values of Pension Plan Assets by Asset Class (Details) - USD ($) $ in Millions	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
(Payables) receivables, net	$ (89)	$ (57)
Total	5,646	5,366
Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	5,735	5,423
Fair Value, Inputs, Level 1, 2 and 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	540	461
Fair Value, Inputs, Level 1, 2 and 3 | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	7	680
Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	57	58
Fair Value, Inputs, Level 1, 2 and 3 | Commingled equity funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	1,059	652
Fair Value, Inputs, Level 1, 2 and 3 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	801	589
Fair Value, Inputs, Level 1, 2 and 3 | Government issued securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	552	574
Fair Value, Inputs, Level 1, 2 and 3 | Commingled fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	1,293	1,298
Fair Value, Inputs, Level 1, 2 and 3 | Alternatives
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	778	770
Fair Value, Inputs, Level 1, 2 and 3 | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	648	341
Level 1
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	1,114	1,825
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	459	450
Level 1 | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	7	680
Level 1 | Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	57	50
Level 1 | Commingled equity funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	50
Level 1 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	4	16
Level 1 | Government issued securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	521	544
Level 1 | Commingled fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	23
Level 1 | Alternatives
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	0
Level 1 | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	66	12
Level 2
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	1,359	1,579
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	76	6
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	8
Level 2 | Commingled equity funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	106	52
Level 2 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	797	573
Level 2 | Government issued securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	31	30
Level 2 | Commingled fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	350	525
Level 2 | Alternatives
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	0	56
Level 2 | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	(1)	329
Level 3
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	583	0	$ 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 Investments
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	583	0
NAV
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	2,679	2,019
NAV | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	5	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	953	550
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	943	750
NAV | Alternatives
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	778	714
NAV | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	$ 0	$ 0