Retirement benefits (Tables)

3 Months Ended

Sep. 30, 2020

Retirement Benefits [Abstract]

Schedule of net pension benefit expense

Net pension benefit expense recognized included the following components:

	Three Months Ended
	September 30,
	2020			2019
Service cost	$	22,810		$	19,549
Interest cost	25,417			33,993
Expected return on plan assets	(66,402		)	(63,895		)
Amortization of prior service cost	843			1,509
Amortization of net actuarial loss	52,331			39,561
Amortization of initial net obligation	5			4
Net pension benefit expense	$	35,004		$	30,721