Retirement benefits (Tables)

3 Months Ended

Sep. 30, 2022

Retirement Benefits [Abstract]

Net pension benefit expense

Net pension benefit expense recognized included the following components:

	Three Months Ended
	September 30,
	2022		2021
Service cost	$	14,253	$	20,662
Interest cost	46,351		27,429
Expected return on plan assets	(66,345)		(67,328)
Amortization of prior service cost	210		934
Amortization of net actuarial loss	6,443		37,531
Amortization of initial net obligation	—		2
Net pension benefit expense	$	912	$	19,230