Retirement benefits (Tables)

6 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Net pension (benefit) expense

Net pension (benefit) expense recognized included the following components:

	Three Months Ended				Six Months Ended
	December 31,				December 31,
	2023		2022		2023		2022
Service cost	$	12,420	$	13,682	$	25,947	$	27,935
Interest cost	67,552		61,084		134,433		107,435
Expected return on plan assets	(88,233)		(82,213)		(176,481)		(148,558)
Amortization of prior service cost	334		242		636		452
Amortization of net actuarial loss	2,793		6,839		3,975		13,282
Net pension (benefit) expense	$	(5,134)	$	(366)	$	(11,490)	$	546