Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Revenue		$ 154,870	$ 163,267
COSTS AND EXPENSES
Amortization		41,876	30,777
General and administrative		9,474	8,804
Pre-development, reclamation, and other		4,434	4,225
Total costs and expenses		191,148	149,829
OTHER INCOME (EXPENSE), NET
Loss on debt extinguishments			0
Fair value adjustments, net, pretax		9,120	4,654
Interest expense, net of capitalized interest		(6,454)	(5,965)
Other, net		60	513
Total other income (expense), net		2,726	(798)
Total		(33,552)	12,640
Income and mining tax (expense) benefit		8,658	(11,949)
Income (loss) from continuing operations		(24,894)	691
Income (loss) from discontinued operations		5,693	550
NET INCOME (LOSS)		(19,201)	1,241
OTHER COMPREHENSIVE INCOME (LOSS), Net of Tax:
Unrealized gain (loss) on debt and equity securities		59	(278)
Reclassification adjustments for impairment of equity securities			0
Other comprehensive income (loss)		59	(278)
COMPREHENSIVE INCOME (LOSS)		$ (19,142)	$ 963
Basic EPS
Income (Loss) from Continuing Operations, Per Basic Share		$ (0.120)	$ 0.004
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share		0.030	0.003
Earnings Per Share, Basic	[1]	(0.090)	0.007
Diluted EPS
Income (Loss) from Continuing Operations, Per Diluted Share		(0.120)	0.004
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share		0.030	0.003
Earnings Per Share, Diluted	[1]	$ (0.090)	$ 0.007
Product [Member]
COSTS AND EXPENSES
Costs applicable to sales	[2]	$ 131,650	$ 99,340
Mineral, Exploration [Member]
COSTS AND EXPENSES
Costs applicable to sales		$ 3,714	$ 6,683

[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.