Note 3 - Properties, Plants, Equipment and Mineral Interests, and Lease Commitments (Tables)

12 Months Ended

Dec. 31, 2014

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment [Table Text Block]

	December 31,
	2014		2013
Mining properties, including asset retirement obligations	$	336,962	$	312,692
Development costs		250,340		204,598
Plants and equipment		698,100		626,818
Land		15,799		15,799
Mineral interests		929,844		946,144
Construction in progress		224,216		200,921
		2,455,261		2,306,972
Less accumulated depreciation, depletion and amortization		623,697		515,371
Net carrying value	$	1,831,564	$	1,791,601

Operating Leases of Lessee Disclosure [Table Text Block]

Year ending December 31,
2015	$	3,456
2016		3,364
2017		2,962
2018		966
2019		968
Thereafter		2,081
Total	$	13,797