Note 2 - Revision of Previously Issued Financial Statements for Immaterial Misstatements - Impact of Error Corrections and Prior Period Adjustments (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2016	Dec. 31, 2015
Inventories: Concentrate, doré, and stockpiled ore		$ 53,172	$ 29,366
Total current assets		164,150	321,236
Properties, plants, equipment and mineral interests, net	[1]	2,520,004	1,999,311
Total assets	[2]	2,703,944	2,345,158	$ 2,355,795
Deferred tax liability		173,537	124,352
Total liabilities		1,012,981	883,881
Accumulated deficit		(248,308)	(218,089)	(185,041)	$ (242,191)
Total shareholders' equity		1,690,963	1,461,277	1,462,240	1,329,300	$ 1,329,300
Total liabilities and shareholders' equity		2,703,944	2,345,158
Depreciation, depletion and amortization	[2]	134,044	120,599	123,631
Total cost of sales		488,038	425,326	461,956
Gross profit		79,099	152,449	184,001
Income (loss) from operations	[2]	(39,126)	60,106	109,439
Foreign Currency Transaction Gain (Loss), Realized		10,310	(9,680)	(2,737)
Total other (expense) income		5,862	(67,663)	(19,780)
Income (Loss) from continuing operations		(33,264)	(7,557)	89,659
Income tax (provision) benefit		6,701	(20,963)	(28,090)
Net Income (Loss) Attributable to Parent, Total		(26,563)	(28,520)	61,569
(Loss) income applicable to common shareholders		(27,115)	(29,072)	61,017
Comprehensive income (loss)		$ (44,370)	$ (17,291)	$ 59,598
Basic (loss) income per common share after preferred dividends (in dollars per share)		$ (0.06)	$ (0.07)	$ 0.16
Diluted (loss) income per common share after preferred dividends (in dollars per share)		$ (0.06)	$ (0.07)	$ 0.16
Depreciation, depletion and amortization		$ 140,905	$ 126,467	$ 124,918
Foreign exchange loss (gain)		(7,104)	10,208	4,460
Deferred income taxes		$ (9,699)	19,392	2,774
Previously Reported [Member]
Inventories: Concentrate, doré, and stockpiled ore			28,455
Total current assets			320,325
Properties, plants, equipment and mineral interests, net			2,020,021
Total assets			2,364,957
Deferred tax liability			121,546
Total liabilities			881,075
Accumulated deficit			(195,484)	(167,437)	(232,565)
Total shareholders' equity			1,483,882	1,479,844	1,338,926
Total liabilities and shareholders' equity			2,364,957
Depreciation, depletion and amortization			116,062	116,126
Total cost of sales			420,789	454,451
Gross profit			156,986	191,506
Income (loss) from operations			64,643	116,944
Foreign Currency Transaction Gain (Loss), Realized			(10,300)	(2,926)
Total other (expense) income			(68,283)	(19,969)
Income (Loss) from continuing operations			(3,640)	96,975
Income tax (provision) benefit			(19,879)	(27,428)
Net Income (Loss) Attributable to Parent, Total			(23,519)	69,547
(Loss) income applicable to common shareholders			(24,071)	68,995
Comprehensive income (loss)			$ (12,290)	$ 67,576
Basic (loss) income per common share after preferred dividends (in dollars per share)			$ (0.06)	$ 0.18
Diluted (loss) income per common share after preferred dividends (in dollars per share)			$ (0.06)	$ 0.18
Depreciation, depletion and amortization			$ 121,930	$ 117,413
Foreign exchange loss (gain)			10,828	4,649
Deferred income taxes			18,308	2,112
Restatement Adjustment [Member]
Inventories: Concentrate, doré, and stockpiled ore			911
Total current assets			911
Properties, plants, equipment and mineral interests, net			(20,710)
Total assets			(19,799)
Deferred tax liability			2,806
Total liabilities			2,806
Accumulated deficit			(22,605)	(17,604)	(9,626)
Total shareholders' equity			(22,605)	(17,604)	$ (9,626)
Total liabilities and shareholders' equity			(19,799)
Depreciation, depletion and amortization			4,537	7,505
Total cost of sales			4,537	7,505
Gross profit			(4,537)	(7,505)
Income (loss) from operations			(4,537)	(7,505)
Foreign Currency Transaction Gain (Loss), Realized			620	189
Total other (expense) income			620	189
Income (Loss) from continuing operations			(3,917)	(7,316)
Income tax (provision) benefit			(1,084)	(662)
Net Income (Loss) Attributable to Parent, Total			(5,001)	(7,978)
(Loss) income applicable to common shareholders			(5,001)	(7,978)
Comprehensive income (loss)			$ (5,001)	$ (7,978)
Basic (loss) income per common share after preferred dividends (in dollars per share)			$ (0.01)	$ (0.02)
Diluted (loss) income per common share after preferred dividends (in dollars per share)			$ (0.01)	$ (0.02)
Depreciation, depletion and amortization			$ 4,537	$ 7,505
Foreign exchange loss (gain)			(620)	(189)
Deferred income taxes			$ 1,084	$ 662

[1] Amounts reported as of and for the years ended December 31, 2017 and 2016 have been revised. See Note 2 for more information.

[2] Amounts reported as of and for the years ended December 31, 2017 and 2016 have been revised. See Note 2 for more information.