Retirement benefits (Tables)

6 Months Ended

Dec. 31, 2019

Retirement Benefits [Abstract]

Schedule of net pension benefit expense

Net pension benefit expense recognized included the following components:

	Three Months Ended						Six Months Ended
	December 31,						December 31,
	2019			2018			2019			2018
Service cost	$	21,449		$	17,983		$	40,998		$	38,492
Interest cost	35,851			40,551			69,844			80,417
Expected return on plan assets	(66,883		)	(62,701		)	(130,778		)	(125,578		)
Amortization of prior service cost	1,309			1,677			2,818			3,325
Amortization of net actuarial loss	42,779			30,692			82,340			59,985
Amortization of initial net obligation	5			4			9			9
Net pension benefit expense	$	34,510		$	28,206		$	65,231		$	56,650