Note 11 - Self-Insurance (Details Textual) $ in Thousands	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)
Operating Lease, Liability	$ 638	$ 712
Restricted Cash and Cash Equivalents	4,282	4,281	$ 4,033
Future Workers' Compensation Claim Payments [Member]
Restricted Cash and Cash Equivalents	$ 4,300	$ 4,300
Mining Properties and Mineral Rights [Member]
Number of Mining Units	4	7
Geographic Spread of Mining Units, in Miles	7	11
Operating Lease, Liability	$ 250,400	$ 262,000