Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Sales of products	$ 210,852	$ 136,925
Cost of sales and other direct production costs	96,709	85,887
Depreciation, depletion and amortization	49,331	39,666
Total cost of sales	146,040	125,553
Gross profit	64,812	11,372
Other operating expenses:
General and administrative	8,007	8,939
Exploration	5,951	2,530
Pre-development	739	535
Other operating expense	3,639	920
Ramp-up and suspension costs	4,318	12,996
Provision for closed operations and environmental matters	3,709	516
Total other operating expense	26,363	26,436
Income (loss) from operations	38,449	(15,064)
Other income (expense):
Gain on exchange of investments	1,158	0
Unrealized loss on investments	(3,506)	(978)
Gain on derivative contracts	473	7,893
Net foreign exchange (loss) gain	(2,064)	6,636
Other non-operating expense	(161)	(423)
Interest expense	(10,744)	(16,311)
Total other expense	(14,844)	(3,183)
Income (loss) before income and mining taxes	23,605	(18,247)
Income and mining tax (provision) benefit	(4,634)	1,062
Net income (loss)	18,971	(17,185)
Preferred stock dividends	(138)	(138)
Income (loss) applicable to common stockholders	18,833	(17,323)
Comprehensive income (loss):
Net income (loss)	18,971	(17,185)
Change in fair value of derivative contracts designated as hedge transactions	1,832	(19,335)
Comprehensive income (loss)	$ 20,803	$ (36,520)
Basic income (loss) per common share after preferred dividends (in dollars per share)	$ 0.04	$ (0.03)
Diluted income (loss) per common share after preferred dividends (in dollars per share)	$ 0.03	$ (0.03)
Weighted average number of common shares outstanding - basic (in shares)	534,101	523,215
Weighted average number of common shares outstanding - diluted (in shares)	540,527	523,215
Cash dividends per common share (in dollars per share)	$ 0.00875	$ 0.0025