Note 7 - Pension and Post-retirement Benefits - Net Periodic Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Pension Plan [Member]
Service cost				$ 1,405
Interest cost	1,531	1,574	4,560	4,659
Expected return on plan assets	(1,300)	(1,284)	(3,876)	(3,878)
Amortization of net loss	5	6	17	102
	236	296	701	2,288
Other Postretirement Benefits Plan [Member]
Service cost	21	23	64	70
Interest cost	69	67	203	203
Amortization of net loss	24	30	74	90
	(20)	(48)	(62)	(142)
Amortization of prior service credit	$ (134)	$ (168)	$ (403)	$ (505)