Pension and Other Postretirement Benefits - Schedule of Assumptions Used (Details)	12 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Pension benefits
Weighted-average assumptions used to determine benefit obligations
Discount rate	5.50%	5.50%	5.50%
Weighted-average assumptions used to determine net periodic benefit costs
Expected return on plan assets	5.90%	5.60%	5.30%
Pension benefits | Service Cost
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate	5.60%	5.50%	5.30%
Pension benefits | Interest Cost
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate	5.00%	5.30%	5.40%
Postretirement benefits
Weighted-average assumptions used to determine benefit obligations
Discount rate	5.40%	5.30%	5.40%
Postretirement benefits | Service Cost
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate	5.60%	5.50%	5.30%
Postretirement benefits | Interest Cost
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate	4.90%	5.30%	5.40%