Retirement benefits (Tables)

3 Months Ended

Sep. 30, 2019

Retirement Benefits [Abstract]

Schedule of net pension benefit expense

Net pension benefit expense recognized included the following components:

	Three Months Ended
	September 30,
	2019			2018
Service cost	$	19,549		$	20,509
Interest cost	33,993			39,866
Expected return on plan assets	(63,895		)	(62,877		)
Amortization of prior service cost	1,509			1,648
Amortization of net actuarial loss	39,561			29,293
Amortization of initial net obligation	4			4
Net pension benefit expense	$	30,721		$	28,443