Retirement Benefit Obligations - Schedule of Weighted-Average Asset Allocations, by Asset Category (Detail)	Jun. 30, 2023	Jun. 30, 2022
Asset Category:
Benefit plan weighted-average asset allocations	100.00%	100.00%
Equity Securities
Asset Category:
Benefit plan weighted-average asset allocations	15.00%	15.00%
Debt securities
Asset Category:
Benefit plan weighted-average asset allocations	72.00%	75.00%
Cash And Other
Asset Category:
Benefit plan weighted-average asset allocations	13.00%	10.00%