Retirement Benefits - Summary of other postretirement benefit plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Amounts recognized on the Consolidated Balance Sheet
Pensions and other postretirement benefits	$ (551,510)	$ (639,939)
Other Postretirement Benefits Plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	48,876	63,739
Service cost	330	206
Interest cost	3,004	982
Acquisition	39,112	0
Actuarial gain	(4,403)	(11,220)
Benefits paid	(8,352)	(4,831)
Benefit obligation at end of year	78,567	48,876
Funded status	(78,567)	(48,876)
Amounts recognized on the Consolidated Balance Sheet
Other accrued liabilities	(7,831)	(4,971)
Pensions and other postretirement benefits	(70,736)	(43,905)
Net amount recognized	(78,567)	(48,876)
Amounts recognized in Accumulated Other Comprehensive (Loss)
Net actuarial gain	$ (17,952)	$ (15,154)