Note 12 - Property and Equipment, Net - Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Property and equipment, gross	$ 1,539,875	$ 1,506,301
Less: accumulated depreciation and depletion	1,008,418	997,091
Property and equipment, net	531,457	509,210
Equipment and Vehicles [Member]
Property and equipment, gross	1,016,327	994,602
Mining Properties and Mineral Rights [Member]
Property and equipment, gross	226,682	219,843
Land and Land Improvements [Member]
Property and equipment, gross	107,816	105,733
Building and Building Improvements [Member]
Property and equipment, gross	105,190	103,658
Furniture and Fixtures [Member]
Property and equipment, gross	$ 83,860	$ 82,465