Retirement benefits (Tables)

3 Months Ended

Sep. 30, 2021

Retirement Benefits [Abstract]

Net pension benefit expense

Net pension benefit expense recognized included the following components:

	Three Months Ended
	September 30,
	2021		2020
Service cost	$	20,662	$	22,810
Interest cost	27,429		25,417
Expected return on plan assets	(67,328)		(66,402)
Amortization of prior service cost	934		843
Amortization of net actuarial loss	37,531		52,331
Amortization of initial net obligation	2		5
Net pension benefit expense	$	19,230	$	35,004