Retirement benefits (Tables)

6 Months Ended

Dec. 31, 2017

Pension Plans

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of defined benefit plans disclosures

Net pension benefit cost recognized included the following components:

	Three Months Ended						Six Months Ended
	December 31,						December 31,
	2017			2016			2017			2016
Service cost	$	18,242		$	23,116		$	41,300		$	47,339
Interest cost	36,138			29,972			71,824			61,468
Expected return on plan assets	(65,350		)	(60,180		)	(128,526		)	(117,797		)
Amortization of prior service cost	1,511			1,683			3,615			3,399
Amortization of net actuarial loss	35,468			54,325			74,150			105,752
Amortization of initial net obligation	5			5			10			10
Net pension benefit cost	$	26,014		$	48,921		$	62,373		$	100,171