Note 11 - Property and Equipment, Net - Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	[1]
Property and equipment, gross	$ 1,506,301				$ 1,342,395
Less: accumulated depreciation and depletion	997,091				908,891
Property and equipment, net	509,210	$ 500,827	$ 464,593	$ 450,250	433,504
Equipment and Vehicles [Member]
Property and equipment, gross	994,602				870,672
Mining Properties and Mineral Rights [Member]
Property and equipment, gross	219,843				191,982
Land and Land Improvements [Member]
Property and equipment, gross	105,733				108,518
Building and Building Improvements [Member]
Property and equipment, gross	103,658				96,180
Furniture and Fixtures [Member]
Property and equipment, gross	$ 82,465				$ 75,043

[1] These balances do not include amounts held for sale (see Note 2).