Note 2 - Acquisitions - Components of Fair Value of Acquisitions and Allocation of Purchase Price For Acquisition of Tennibac-Graphion Inc. (Details) - USD ($) $ in Thousands		1 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Aug. 31, 2018	Jun. 30, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Payments to Acquire Businesses, Net of Cash Acquired, Total				$ 127,924	$ 10,397	$ 153,814
Goodwill, Ending Balance			$ 281,503	281,503	$ 211,751
Tenibac-Graphion, Inc. [Member]
Payments to Acquire Businesses, Gross	$ 57,284		57,284
Less, cash acquired	(558)		(558)
Payments to Acquire Businesses, Net of Cash Acquired, Total	56,726	$ 57,300	56,726
Other acquired assets	5,023		3,770	3,770
Other acquired assets			(1,253)
Inventories	324		324	324
Inventories
Customer Backlog	1,000		200	200
Customer Backlog			(800)
Property, plant, & equipment	2,490		2,471	2,471
Property, plant, & equipment			(19)
Identifiable intangible assets	15,960		16,860	16,860
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles			900
Goodwill, Ending Balance	32,949		34,360	34,360
Goodwill			1,411
Liabilities assumed	$ (1,020)		(1,259)	$ (1,259)
Liabilities assumed			$ (239)