Note 3 - Revision of Previously Issued Financial Statements for Immaterial Misstatements (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Inventories: Concentrates, doré, and stockpiled ore				$ 57,567		$ 30,078
Total current assets		$ 341,627		284,312		178,838
Properties, plants, equipment and mineral interests, net		2,310,810	[1]	2,378,074	[1]	2,447,450
Total assets	[1]	2,728,808		2,700,210		2,660,774
Accrued taxes		12,306		5,774
Total current liabilities		160,383		147,210
Deferred tax liability		149,706		156,091		157,637
Total liabilities		968,021		986,425		964,240
Accumulated deficit		(353,651)		(368,074)		(349,220)
Total shareholders' equity		1,760,787		1,713,785		1,696,534	$ 1,690,426
Total liabilities and shareholders' equity		2,728,808		2,700,210		2,660,774
Cost of sales and other direct production costs		417,879		382,663		447,985
Depreciation, depletion and amortization	[1]	171,793		148,110		191,451
Total cost of sales		589,672		530,773		639,436
Gross profit		217,801		161,100		33,830
Income from operations	[1]	83,420		66,978		(46,678)
Total		5,526		(1,258)		(113,227)
Income and mining tax benefit (provision)		29,569		(8,199)		18,318
Net income (loss)		35,095		(9,457)		(94,909)
Loss applicable to common shareholders		34,543		(10,009)		(95,461)
Comprehensive loss		$ 39,528		$ (5,036)		$ (89,750)
Basic loss per common share after preferred dividends (in dollars per share)		$ 0.06		$ (0.02)		$ (0.19)
Diluted loss per common share after preferred dividends (in dollars per share)		$ 0.06		$ (0.02)		$ (0.19)
Depreciation, Depletion and Amortization, Total		$ 172,651		$ 155,006		$ 196,408
Deferred income taxes				(3,818)		(29,968)
Cash provided by operating activities		$ 220,337		180,793		120,866
Previously Reported [Member]
Inventories: Concentrates, doré, and stockpiled ore				57,936		30,364
Total current assets				284,681		179,124
Properties, plants, equipment and mineral interests, net				2,345,219		2,423,698
Total assets				2,667,724		2,637,308
Accrued taxes				8,349
Total current liabilities				149,785
Deferred tax liability				132,475		138,282
Total liabilities				965,384		944,885
Accumulated deficit				(379,519)		(353,331)
Total shareholders' equity				1,702,340		1,692,423
Total liabilities and shareholders' equity				2,667,724		2,637,308
Cost of sales and other direct production costs				389,040		450,349
Depreciation, depletion and amortization				157,130		199,518
Total cost of sales				546,170		649,867
Gross profit				145,703		23,399
Income from operations				51,581		(57,109)
Total				(16,655)		(123,658)
Income and mining tax benefit (provision)				(135)		24,101
Net income (loss)				(16,790)		(99,557)
Loss applicable to common shareholders				(17,342)		(100,109)
Comprehensive loss				$ (12,369)		$ (94,398)
Basic loss per common share after preferred dividends (in dollars per share)				$ (0.03)		$ (0.20)
Diluted loss per common share after preferred dividends (in dollars per share)				$ (0.03)		$ (0.20)
Depreciation, Depletion and Amortization, Total				$ 164,026		$ 204,475
Deferred income taxes				(5,505)		(33,387)
Cash provided by operating activities				180,793		120,866
Revision of Prior Period, Adjustment [Member]
Inventories: Concentrates, doré, and stockpiled ore				(369)		(286)
Total current assets				(369)		(286)
Properties, plants, equipment and mineral interests, net				32,855		23,752
Total assets				32,486		23,466
Accrued taxes				(2,575)
Total current liabilities				(2,575)
Deferred tax liability				23,616		19,355
Total liabilities				21,041		19,355
Accumulated deficit				11,445		4,111
Total shareholders' equity				11,445		4,111
Total liabilities and shareholders' equity				32,486		23,466
Cost of sales and other direct production costs				(6,377)		(2,364)
Depreciation, depletion and amortization				(9,020)		(8,067)
Total cost of sales				(15,397)		(10,431)
Gross profit				15,397		10,431
Income from operations				15,397		10,431
Total				15,397		10,431
Income and mining tax benefit (provision)				(8,064)		(5,783)
Net income (loss)				7,333		4,648
Loss applicable to common shareholders				7,333		4,648
Comprehensive loss				$ 7,333		$ 4,648
Basic loss per common share after preferred dividends (in dollars per share)				$ 0.01		$ 0.01
Diluted loss per common share after preferred dividends (in dollars per share)				$ 0.01		$ 0.01
Depreciation, Depletion and Amortization, Total				$ (9,020)		$ (8,067)
Deferred income taxes				1,687		3,419
Cash provided by operating activities				$ 0		$ 0

[1] Amounts reported as of and for the years ended December 31, 2020 and 2019 have been revised. See Note 3 for more information.