Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net income (loss)	$ 13,737	$ (1,893)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Deferred income tax expense	3,051	788
Depreciation, amortization, depletion and accretion	2,106	2,297
Operating lease expense	379	774
Amortization of debt discount and debt issuance costs	591	354
Stock-based compensation expense	421	506
Earnings from equity method investments	(18,312)	(8,273)
Other non-cash items, net	(273)	0
Changes in operating assets and liabilities:
Receivables and related party receivables	2,147	2,988
Prepaid expenses and other assets	1,178	226
Inventories, net	1,548	1,572
Other long-term assets, net	(1,817)	(89)
Accounts payable	(706)	(1,477)
Accrued payroll and related liabilities	(1,043)	(973)
Other current liabilities	1,305	(23)
Operating lease liabilities	2,104	(634)
Other long-term liabilities	(2,113)	(22)
Distributions from equity method investees, return on investment	17,644	17,116
Net cash provided by operating activities	21,947	13,237
Cash flows from investing activities
Distributions from equity method investees in excess of cumulative earnings	5,607	0
Acquisition of property, plant, equipment, and intangible assets, net	(1,321)	(1,289)
Mine development costs	(248)	(447)
Proceeds from sale of property and equipment	848	0
Net cash provided by (used in) investing activities	4,886	(1,736)
Cash flows from financing activities
Principal payments on term loan	(10,000)	(6,000)
Principal payments on finance lease obligations	(315)	(340)
Dividends paid	0	(4,518)
Repurchase of common shares	0	(159)
Repurchase of common shares to satisfy tax withholdings	(216)	(376)
Net cash used in financing activities	(10,531)	(11,393)
Increase in Cash and Cash Equivalents and Restricted Cash	16,302	108
Cash and Cash Equivalents and Restricted Cash, beginning of period	35,932	17,080
Cash and Cash Equivalents and Restricted Cash, end of period	52,234	17,188
Supplemental disclosure of non-cash investing and financing activities:
Acquisition of property, plant and equipment through accounts payable	765	1,890
Dividends payable	$ 0	$ 105