Note 2 - Acquisitions (Details Textual) - USD ($) $ in Thousands				1 Months Ended	3 Months Ended				9 Months Ended	12 Months Ended				21 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Aug. 31, 2018	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2019
Goodwill, Ending Balance						$ 281,503			$ 281,503	$ 281,503		$ 211,751		$ 281,503
Payments to Acquire Businesses, Net of Cash Acquired, Total										127,924		10,397	$ 153,814
Business Combination, Contingent Consideration, Liability, Total	[1]					6,418			6,418	$ 6,418		7,535		6,418
Other Intangible Assets [Member]
Finite-Lived Intangible Asset, Useful Life										10 years
GS Engineering [Member]
Payments to Acquire Businesses, Gross						30,500				$ 30,502
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total						8,910			8,910	8,910				8,910
Goodwill, Ending Balance						17,976			17,976	17,976				17,976
Payments to Acquire Businesses, Net of Cash Acquired, Total										29,880
GS Engineering [Member] | Developed Technology Rights [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total						$ 5,600			5,600	5,600				5,600
Finite-Lived Intangible Asset, Useful Life						15 years
GS Engineering [Member] | Trademarks [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total						$ 900			900	900				900
GS Engineering [Member] | Customer Relationships [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total						$ 2,400			2,400	2,400				2,400
Finite-Lived Intangible Asset, Useful Life						13 years
Agile Magnetics [Member]
Payments to Acquire Businesses, Gross		$ 39,194							39,194
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total		13,718				$ 18,150	$ 13,718		18,150	18,150	$ 13,718			18,150
Goodwill, Ending Balance		20,142				15,614	20,142		15,614	15,614	20,142			15,614
Payments to Acquire Businesses, Net of Cash Acquired, Total		39,193					$ 39,200		39,193
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles									4,432
Agile Magnetics [Member] | Forecast [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total					$ 1,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles					$ 500
Agile Magnetics [Member] | Trademarks [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total						3,800			3,800	3,800				3,800
Agile Magnetics [Member] | Customer Relationships [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total						14,300			14,300	14,300				14,300
Finite-Lived Intangible Asset, Useful Life							13 years
Agile Magnetics [Member] | Noncompete Agreements [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total						100			100	100				100
Finite-Lived Intangible Asset, Useful Life							5 years
Tenibac-Graphion, Inc. [Member]
Payments to Acquire Businesses, Gross		57,284							57,284
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total		15,960				16,860	$ 15,960		16,860	16,860	15,960			16,860
Goodwill, Ending Balance		32,949				34,360	32,949		34,360	34,360	32,949			34,360
Payments to Acquire Businesses, Net of Cash Acquired, Total		56,726		$ 57,300					56,726
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles									900
Business Acquisition, Goodwill, Expected Tax Deductible Amount						34,400			34,400	34,400				34,400
Tenibac-Graphion, Inc. [Member] | Trademarks [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total						4,200			4,200	4,200				4,200
Tenibac-Graphion, Inc. [Member] | Customer Relationships [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total						11,300			11,300	11,300				11,300
Finite-Lived Intangible Asset, Useful Life				15 years
Tenibac-Graphion, Inc. [Member] | Other Intangible Assets [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total						1,400			1,400	1,400				1,400
Finite-Lived Intangible Asset, Useful Life				5 years
Piazza Rosa Group [Member]
Payments to Acquire Businesses, Gross			$ 10,056											10,056
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total			4,087			3,472		$ 4,087	3,472	3,472				3,472
Goodwill, Ending Balance		$ 7,100	6,218			$ 7,076	7,100	6,218	$ 7,076	7,076	7,100			7,076
Payments to Acquire Businesses, Net of Cash Acquired, Total			10,056				$ 900	10,100						12,673
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles								(600)						(615)
Other Payments to Acquire Businesses								2,800			$ 2,600			$ 2,617
Business Combination, Contingent Consideration, Liability, Total												1,000
Piazza Rosa Group [Member] | Trademarks (Indefinite-Lived) [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total			1,600					1,600
Piazza Rosa Group [Member] | Customer Relationships [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total			2,300					$ 2,300
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life								8 years
Piazza Rosa Group [Member] | Other Intangible Assets [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total			200					$ 200
Horizon Scientific Inc. [Member]
Business Combination, Deferred Compensation Due on Second Anniversary			2,800					2,800
Business Combination, Deferred Compensation Due on Third Anniversary			$ 5,600					$ 5,600
Business Combination, Deferred Compensation Arrangements										$ 2,800		$ 2,800

[1] The fair value of our contingent consideration arrangement is determined based on our evaluation as to the probability and amount of any deferred compensation that has been earned to date.