Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities:
Net (loss) income	$ (25,533)	$ 8,240
Non-cash elements included in net (loss) income:
Depreciation, depletion and amortization	40,267	29,490
Unrealized gain on investments	(96)	(310)
Adjustment of inventory to market value	1,399
Gain on disposition of properties, plants, equipment, and mineral interests		(129)
Provision for reclamation and closure costs	1,594	1,323
Stock compensation	1,580	1,089
Deferred income taxes	(8,293)	(438)
Amortization of loan origination fees	625	449
Loss (gain) on derivative contracts	3,686	(9,094)
Foreign exchange loss (gain)	5,550	(3,399)
Other non-cash items, net	2	2
Change in assets and liabilities:
Accounts receivable	(5,063)	(7,266)
Inventories	3,171	(6,762)
Other current and non-current assets	1,124	(3,171)
Accounts payable and accrued liabilities	(9,496)	13,956
Accrued payroll and related benefits	7,212	(3,927)
Accrued taxes	1,237	218
Accrued reclamation and closure costs and other non-current liabilities	1,064	(3,888)
Cash provided by operating activities	20,030	16,383
Investing activities:
Additions to properties, plants, equipment and mineral interests	(33,071)	(17,635)
Proceeds from disposition of properties, plants and equipment	1	151
Purchases of investments		(31,182)
Maturities of investments		30,501
Net cash used in investing activities	(33,070)	(18,165)
Financing activities:
Acquisition of treasury shares		(1,225)
Dividends paid to common stockholders	(1,209)	(998)
Dividends paid to preferred stockholders	(138)	(138)
Credit facility fees paid	(39)
Borrowings on debt	58,000	31,024
Repayments of debt	(58,000)
Repayments of finance leases	(1,261)	(1,322)
Net cash (used in) provided by financing activities	(2,647)	27,341
Effect of exchange rates on cash	95	876
Net (decrease) increase in cash, cash equivalents and restricted cash and cash equivalents	(15,592)	26,435
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	28,414	187,139
Cash, cash equivalents and restricted cash and cash equivalents at end of period	12,822	213,574
Significant non-cash investing and financing activities:
Addition of finance lease obligations and right-of-use assets	3,498	2,446
Recognition of operating lease liabilities and right-of-use assets	22,365
Payment of accrued compensation in stock		$ 4,863