Retirement benefits (Tables)

9 Months Ended

Mar. 31, 2023

Retirement Benefits [Abstract]

Net pension benefit expense

Net pension benefit expense recognized included the following components:

	Three Months Ended				Nine Months Ended
	March 31,				March 31,
	2023		2022		2023		2022
Service cost	$	14,599	$	18,238	$	42,534	$	57,599
Interest cost	59,021		27,953		166,456		82,941
Expected return on plan assets	(80,137)		(67,024)		(228,695)		(201,487)
Amortization of prior service cost	227		1,028		679		3,084
Amortization of net actuarial (gain) loss	(657)		39,570		12,625		118,186
Amortization of initial net obligation	—		2		—		6
Net pension benefit expense	$	(6,947)	$	19,767	$	(6,401)	$	60,329