POSTRETIREMENT BENEFITS AND EMPLOYEE STOCK OWNERSHIP PLAN - Additional Information (Details) - USD ($)	12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 1991	Jun. 30, 1989
Defined Benefit Plan Disclosure [Line Items]
Defined contribution expense	$ 534,000,000	$ 425,000,000	$ 392,000,000
Accumulated benefit obligation	$ 12,500,000,000	$ 11,600,000,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets (in percent)	6.00%	6.00%	5.90%
Expected future employer contributions, next fiscal year	$ 218,000,000
Pension Benefits | Series A Preferred Stock
Defined Benefit Plan Disclosure [Line Items]
ESOP, direct loan amount					$ 1,000,000,000.0
ESOP, debt structure, employer loan guarantee	$ 0
Dividend (in dollars per share)	$ 4.08
Liquidation value (in dollars per share)	$ 6.82
Other Retiree Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets (in percent)	8.50%	8.50%	8.40%
Expected future employer contributions, next fiscal year	$ 54,000,000
Other Retiree Benefits | Series B Preferred Stock
Defined Benefit Plan Disclosure [Line Items]
ESOP, direct loan amount				$ 1,000,000,000.0
ESOP, debt structure, employer loan guarantee	$ 672,000,000
Dividend (in dollars per share)	$ 4.08
Liquidation value (in dollars per share)	$ 12.96
Treasury Stock
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets (in percent)	8.50%
Minimum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets (in percent)	8.00%
Minimum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets (in percent)	3.00%
Maximum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets (in percent)	9.00%
Maximum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets (in percent)	5.00%
United States
Defined Benefit Plan Disclosure [Line Items]
Contribution rate (in percent)	12.00%	13.00%	13.00%