Note 7 - Restructuring, Impairment and Plant Closing Costs (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Employee Severance and Accelerated Depreciation [Member] \| Advanced Materials [Member] \| Restructuring Program to Optimize the Segment’s Manufacturing Processes and Cost Structure [Member]
Restructuring Charges	$ 4,000	$ 1,000
Restructuring and Related Cost, Expected Cost	7,000
Employee Severance and Accelerated Depreciation [Member] \| Polyurethanes [Member] \| Restructuring Programs to Reduce Organizational Structure Costs [Member]
Restructuring Charges	2,000	$ 2,000
Restructuring and Related Cost, Expected Cost	5,000
Workforce Reduction and Contract Termination [Member] \| Performance Products [Member] \| European Maleic Anhydride Manufacturing Facility Closure in Moers Germany[Member]
Restructuring Charges	0
Restructuring and Related Cost, Expected Cost	$ 3,000