Retirement Benefits - Summary of other postretirement benefit plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Amounts recognized on the Consolidated Balance Sheet
Pensions and other postretirement benefits	$ (1,055,638)	$ (1,887,414)	[1]
Other Postretirement Benefits Plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	72,130	60,998
Service cost	328	250
Interest cost	983	1,686
Acquisition	0	12,638
Actuarial (gain) loss	(4,139)	1,276
Benefits paid	(5,563)	(4,718)
Benefit obligation at end of year	63,739	72,130
Funded status	(63,739)	(72,130)
Amounts recognized on the Consolidated Balance Sheet
Other accrued liabilities	(5,634)	(6,374)
Pensions and other postretirement benefits	(58,105)	(65,756)
Net amount recognized	(63,739)	(72,130)
Amounts recognized in Accumulated Other Comprehensive (Loss)
Net actuarial gain	(4,311)	(173)
Prior service credit	0	(73)
Net amount recognized	$ (4,311)	$ (246)

[1] *Year ended June 30, 2020 amounts have been adjusted to reflect the change in inventory accounting method, as described in Notes 1 and 7 to the Consolidated Financial Statements.