Note 15 - Properties, Plants, Equipment and Mine Development, net, and Lease Commitments - Major Components of Property, Plants, Equipment and mine development (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment, Gross	$ 4,704,126	$ 4,528,510
Less accumulated depreciation, depletion and amortization	2,010,007	1,862,260
Net carrying value	2,694,119	2,666,250
Mining properties, including asset retirement obligations
Property, Plant and Equipment, Gross	958,858	911,018
Development costs
Property, Plant and Equipment, Gross	671,741	630,391
Plants and equipment
Property, Plant and Equipment, Gross	1,805,236	1,666,577
Land
Property, Plant and Equipment, Gross	35,680	35,112
Mineral interests
Property, Plant and Equipment, Gross	1,166,045	1,164,390
Construction in progress
Property, Plant and Equipment, Gross	$ 66,566	$ 121,022