Note 7 - Goodwill and Other Intangible Assets (Details Textual)	3 Months Ended		6 Months Ended		9 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Number of Reporting Units			3
Goodwill, Impairment Loss	$ 20,165,000		$ 20,165,000	$ 28,000,000
Amortization of Intangible Assets, Total	689,000	$ 690,000			$ 1,380,000	$ 1,380,000
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	2,761,000		2,761,000		2,761,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	2,687,000		2,687,000		2,687,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	2,682,000		2,682,000		2,682,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	2,460,000		2,460,000		2,460,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	2,412,000		2,412,000		2,412,000
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	$ 18,985,000		$ 18,985,000		$ 18,985,000
Lighting Segment [Member]
Number of Reporting Units			2
Goodwill, Impairment Loss			$ 20,165,000
Graphics Segment [Member]
Number of Reporting Units			1
Goodwill, Impairment Loss