Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Revenue		$ 202,117	$ 173,167
COSTS AND EXPENSES
Amortization		29,937	36,162
General and administrative		11,554	8,920
Pre-development, reclamation, and other		13,712	6,555
Total costs and expenses		173,016	176,940
OTHER INCOME (EXPENSE), NET
Loss on debt extinguishments		(9,173)	0
Fair value adjustments, net, pretax		(3,799)	(8,819)
Interest expense, net of capitalized interest		(4,910)	(5,128)
Other, net		3,627	1,881
Total other income (expense), net		(14,255)	(12,066)
Total		14,846	(15,839)
Income and mining tax (expense) benefit		(12,786)	3,939
NET INCOME (LOSS)		2,060	(11,900)
OTHER COMPREHENSIVE INCOME (LOSS), Net of Tax:
Unrealized gain (loss) on hedger, net of tax		27,357	206
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax		(2,721)	0
Other comprehensive income (loss)		24,636	206
COMPREHENSIVE INCOME (LOSS)		$ 26,696	$ (11,694)
Basic EPS
Earnings Per Share, Basic		$ 0.01	$ (0.05)
Diluted EPS
Earnings Per Share, Diluted		$ 0.01	$ (0.05)
Accumulated Deficit [Member]
OTHER INCOME (EXPENSE), NET
NET INCOME (LOSS)		$ 2,060	$ (11,900)
Product
COSTS AND EXPENSES
Costs applicable to sales	[1]	108,147	118,917
Mineral, Exploration
COSTS AND EXPENSES
Costs applicable to sales		$ 9,666	$ 6,386

[1] Excludes amortization.