Retirement benefits (Tables)

9 Months Ended

Mar. 31, 2020

Retirement Benefits [Abstract]

Schedule of net pension benefit expense

Net pension benefit expense recognized included the following components:

	Three Months Ended						Nine Months Ended
	March 31,						March 31,
	2020			2019			2020			2019
Service cost	$	20,967		$	19,126		$	61,965		$	57,618
Interest cost	36,389			40,124			106,233			120,541
Expected return on plan assets	(68,058		)	(62,844		)	(198,836		)	(188,422		)
Amortization of prior service cost	1,411			1,665			4,229			4,990
Amortization of net actuarial loss	41,200			29,988			123,540			89,973
Amortization of initial net obligation	4			4			13			13
Net pension benefit expense	$	31,913		$	28,063		$	97,144		$	84,713