Retirement benefits (Tables)

3 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Net pension (benefit) expense

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

	Three Months Ended
	September 30,
	2023		2022
Service cost	$	13,527	$	14,253
Interest cost	66,881		46,351
Expected return on plan assets	(88,248)		(66,345)
Amortization of prior service cost	302		210
Amortization of net actuarial loss	1,182		6,443
Amortization of initial net obligation	—		—
Net pension (benefit) expense	$	(6,356)	$	912