Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Components of net periodic cost:
Service cost	$ 36	$ 38	$ 107	$ 115
Pension Benefits [Member]
Components of net periodic cost:
Service cost	31	31	93	94
Interest cost	182	173	549	519
Expected return on plan assets	(118)	(115)	(355)	(345)
Recognized net actuarial loss (gain)	106	218	318	654
Amortization of prior service cost	7	22	21	65
Net periodic cost	208	329	626	987
Retiree Health Care Benefits [Member]
Components of net periodic cost:
Service cost	5	7	14	21
Interest cost	13	16	39	48
Expected return on plan assets	0	0	0	0
Recognized net actuarial loss (gain)	(39)	(45)	(116)	(136)
Amortization of prior service cost	(92)	(68)	(276)	(203)
Net periodic cost	$ (113)	$ (90)	$ (339)	$ (270)