Note 7 - Pension and Post-retirement Benefits - Net Periodic Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Pension Plan [Member]
Service cost		$ 714	$ 1,405	$ 2,143
Interest cost	1,574	1,732	4,659	5,259
Expected return on plan assets	(1,284)	(1,560)	(3,878)	(4,739)
Amortization of net loss	6	13	102	39
	296	899	2,288	2,702
Other Postretirement Benefits Plan [Member]
Service cost	23	26	70	79
Interest cost	67	71	203	215
Amortization of net loss	30	4	90	11
	(48)	(94)	(142)	(281)
Amortization of prior service credit	$ (168)	$ (195)	$ (505)	$ (586)