Note 5 - Acquisition and Divestiture (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Mar. 31, 2020
Gain (Loss) on Disposition of Business		$ 9.8	$ (0.0)
Payment for Contingent Consideration Liability, Financing Activities		0.5	$ (0.0)
Gaomei [Member]
Payment for Contingent Consideration Liability, Financing Activities		0.5
Gaomei [Member] | Forecast [Member]
Payment for Contingent Consideration Liability, Financing Activities	$ 1.3
Specialty Service Coatings [Member] | Selling, General and Administrative Expenses [Member]
Gain (Loss) on Disposition of Business		$ 9.8