Retirement benefits (Tables)

9 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Schedule of net pension benefit expense

Net pension benefit expense recognized included the following components:

	Three Months Ended				Nine Months Ended
	March 31,				March 31,
	2021		2020		2021		2020
Service cost	$	21,016	$	20,967	$	63,215	$	61,965
Interest cost	25,661		36,389		76,833		106,233
Expected return on plan assets	(67,201)		(68,058)		(200,410)		(198,836)
Amortization of prior service cost	1,294		1,411		3,583		4,229
Amortization of net actuarial loss	51,094		41,200		156,254		123,540
Amortization of initial net obligation	4		4		13		13
Net pension benefit expense	$	31,868	$	31,913	$	99,488	$	97,144