Note 11 - Self-Insurance (Details Textual) $ in Thousands	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Operating Lease, Liability, Total	$ 712	$ 230
Restricted Cash and Cash Equivalents, Total	4,281	3,417
Future Workers' Compensation Claim Payments [Member]
Restricted Cash and Cash Equivalents, Total	$ 4,300	3,400
Mining Properties and Mineral Rights [Member]
Number of Mining Units	7
Geographic Spread of Mining Units, in Miles	11
Operating Lease, Liability, Total	$ 262,000	$ 280,000