Note 9 - Pension and Post-retirement Benefits - Net Periodic Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Pension Plan [Member]
Service cost
Interest cost	1,366	1,500	2,715	3,006
Expected return on plan assets	(1,309)	(1,279)	(2,603)	(2,563)
Amortization of net loss	9	7	19	14
Total	66	228	131	457
Post Retirement Medical Plan [Member]
Service cost	19	18	37	36
Interest cost	60	67	120	133
Amortization of net loss	21	8	42	15
Total	(35)	(42)	(70)	(85)
Amortization of prior service credit	$ (135)	$ (135)	$ (269)	$ (269)