Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020		Jun. 30, 2019
Revenue		$ 154,249		$ 162,123		$ 327,416		$ 316,993
COSTS AND EXPENSES
Amortization		27,876		43,204		64,038		85,080
General and administrative		8,616		7,750		17,536		17,224
Pre-development, reclamation, and other		18,675		4,334		25,230		8,768
Total costs and expenses		157,037		192,955		333,977		384,103
OTHER INCOME (EXPENSE), NET
Loss on debt extinguishments		0
Fair value adjustments, net, pretax		10,067		(5,296)		1,248		3,824
Interest expense, net of capitalized interest		(5,765)		(6,825)		(10,893)		(13,279)
Other, net		121		643		2,002		703
Total other income (expense), net		4,423		(11,478)		(7,643)		(8,752)
Total		1,635		(42,310)		(14,204)		(75,862)
Income and mining tax (expense) benefit		(2,844)		5,546		1,095		14,204
Income (loss) from continuing operations		(1,209)		(36,764)		(13,109)		(61,658)
Income (loss) from discontinued operations		0		0		0		5,693
NET INCOME (LOSS)		(1,209)	$ (11,900)	(36,764)	$ (19,201)	(13,109)		(55,965)
OTHER COMPREHENSIVE INCOME (LOSS), Net of Tax:
Unrealized gain (loss) on hedger, net of tax		(7,776)		0		(7,570)		0
Unrealized gain (loss) on debt and equity securities		0		0		0		59
Other comprehensive income (loss)		(7,776)	206	0	59	(7,570)		59
COMPREHENSIVE INCOME (LOSS)		$ (8,985)		$ (36,764)		$ (20,679)		$ (55,906)
Basic EPS
Income (Loss) from Continuing Operations, Per Basic Share		$ (0.01)		$ (0.18)		$ (0.05)		$ (0.30)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share		0		0		0		0.03
Earnings Per Share, Basic		(0.01)		(0.18)		(0.05)	[1]	(0.27)	[1]
Diluted EPS
Income (Loss) from Continuing Operations, Per Diluted Share		(0.01)		(0.18)		(0.05)		(0.30)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share		0		0		0		0.03
Earnings Per Share, Diluted		$ (0.01)		$ (0.18)		$ (0.05)	[1]	$ (0.27)	[1]
Accumulated Deficit [Member]
OTHER INCOME (EXPENSE), NET
NET INCOME (LOSS)		$ (1,209)	$ (11,900)	$ (36,764)	$ (19,201)	$ (13,109)
Product
COSTS AND EXPENSES
Costs applicable to sales	[2]	90,015		131,948		208,932		$ 263,598
Mineral, Exploration
COSTS AND EXPENSES
Costs applicable to sales		$ 11,855		$ 5,719		$ 18,241		$ 9,433

[1] Due to rounding, the sum of net income per share from continuing operations and discontinued operations may not equal net income per share.

[2] Excludes amortization.