Retirement benefits (Tables)

9 Months Ended

Mar. 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						Nine Months Ended
	March 31,						March 31,
	2017			2016			2017			2016
Service cost	$	23,632		$	23,680		$	70,971		$	71,199
Interest cost	31,734			45,138			93,202			136,872
Special termination cost	—			—			—			7,088
Expected return on plan assets	(59,480		)	(55,418		)	(177,277		)	(166,633		)
Amortization of prior service cost	1,702			1,868			5,101			5,606
Amortization of net actuarial loss	52,805			42,573			158,557			127,841
Amortization of initial net obligation	4			4			14			12
Net pension benefit cost	$	50,397		$	57,845		$	150,568		$	181,985