Note 10 - Activity of Business Segments - Reconciliation of Total Segment Income to Total Consolidated Net Income (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Consolidated net income	$ 3,719,000	$ 5,342,000
Provision (benefit) for income taxes	1,007,000	(1,028,000)
Operating Segments [Member]
Consolidated net income	6,301,000	5,863,000
Operating Segments [Member] | Building Supply [Member]
Consolidated net income	1,551,000	1,410,000
Operating Segments [Member] | Disposable Protective Apparel [Member]
Consolidated net income	4,750,000	4,453,000
Corporate, Non-Segment [Member]
Consolidated net income	$ 1,575,000	$ 1,549,000