Note 6 - Workers' compensation and occupational disease (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Annual occupational disease benefits discount rate	3.26%
Amount of occupational disease obligation	$ 1.4
Uninsured claims	3.9	$ 1.7
Other long-term liabilities
Uninsured claims	$ 2.4	$ 0.9