CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net loss	$ (75,433)	$ (253,116)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	34,605	44,282
Amortization of debt issuance costs and original issue discount	685	1,055
Provision for doubtful accounts	561	589
Deferred income taxes	884	(2,134)
(Gain) on disposal or impairment of assets	(1,089)	125,778
Foreign currency transaction gain, net		(35)
Stock compensation expense	3,565	4,892
PIK accrual on notes payable, related parties		2,040
Change in fair value of derivative instruments	(2,537)	(930)
Changes in operating assets and liabilities:
Trade accounts and other receivables	1,451	(20,533)
Inventories	14,156	10,524
Prepaid expenses and other current assets	717	724
Accounts payable	(8,759)	11,666
Accrued expenses	3,710	8,687
Income tax receivable, net	69	(357)
Other, net	3,162	2,949
Net cash used in operating activities	(21,598)	(38,818)
Investing activities
Capital expenditures	(2,039)	(2,598)
Net proceeds from asset sales	27,526	21,600
Net cash provided by investing activities	25,487	19,002
Financing activities
Proceeds from long-term debt		12,349
Repayments on long-term debt		(3,250)
Repayments on insurance financing agreement	(1,385)	(1,296)
Payment of debt issuance costs		(989)
Purchase of common stock	(421)	(539)
Net cash provided by financing activities	1,043	6,275
Effect of exchange rate changes on cash		246
Net increase (decrease) in cash and cash equivalents and restricted cash	4,932	(13,295)
Cash and cash equivalents and restricted cash at beginning of year	78,385	91,680
Cash and cash equivalents and restricted cash at end of year	83,317	78,385
Supplemental cash flow information
Interest paid	7,700	2,319
Income taxes paid		457
Russian Proppant
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Loss on sale of business	2,305
Millen, Georgia Facility
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Loss on sale of business	350	$ 25,101
ATM Program
Financing activities
Proceeds from issuance of common stock under ATM program	$ 2,849