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	6 Months Ended	9 Months Ended
	Sep. 30, 2018	Aug. 31, 2018	Mar. 31, 2019	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2018
Payments to Acquire Businesses, Net of Cash Acquired, Total				$ 96,768	$ 10,397
Goodwill, Ending Balance			$ 260,443	260,443		$ 211,751
Tenibac-Graphion, Inc. [Member]
Cash payments	$ 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		3,778	3,778
Other acquired assets			(1,245)
Inventories	324		324	324
Inventories
Customer Backlog	1,000		200	200
Customer Backlog			(800)
Property, plant, & equipment	2,490		3,000	3,000
Property, plant, & equipment			510
Identifiable intangible assets	15,960		16,904	16,904
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles			944
Goodwill, Ending Balance	32,949		33,779	33,779
Goodwill			830
Liabilities assumed	$ (1,020)		(1,259)	$ (1,259)
Liabilities assumed			$ (239)