Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss	$ (53,610)	$ (47,432)
Adjustments to reconcile net loss to net cash used for operating activities:
Depreciation and amortization	2,143	2,438
Change in fair value of warrant	0	5,278
Share-based compensation	5,199	28,541
Asset retirement obligation accretion	106	102
Amortization of intangible	39	38
Amortization of debt issuance costs and discounts	1,338	1,297
Loss on extinguishment of debt	4,896	0
Non-cash interest expense	24	0
Bad debt provision	36	20
Other, net	16	0
Changes in operating assets and liabilities:
Accounts receivable, net	(3,887)	(1,291)
Inventories, net	1,317	(469)
Prepaid expenses and other assets	(1,029)	(889)
Accounts payable and accrued expenses	(5,632)	2,754
Deferred revenue	(591)	(566)
Net cash used for operating activities	(49,635)	(10,179)
Cash flows from investing activities:
Capital expenditures	(577)	(1,334)
Net cash used for investing activities	(577)	(1,334)
Cash flows used for financing activities:
Proceeds from initial offering of common stock	0	68,714
Proceeds from common stock issued via employee stock purchase plan	112	0
Proceeds from issuance of long-term debt	70,000	0
Debt repayment	(50,000)	0
Payments for loan acquisition costs	(3,918)	0
Payments for deferred offering costs	0	(4,695)
Premium paid to retire debt	(2,944)	0
Payments for taxes on share-based compensation	(2,723)	(5,903)
Net cash provided by financing activities	10,527	58,116
Net (decrease) increase in cash and cash equivalents	(39,685)	46,603
Cash and cash equivalents:
Beginning of period	60,599	17,379
End of period	20,914	63,982
Supplemental disclosures of cash flow information:
Cash payments for interest	5,153	4,511
Net (decrease) in capital expenditures included in accounts payable and accrued expenses	(290)	(145)
Net increase/(decrease) in offering costs included in accounts payable and accrued expenses	162	(515)
Accrued withholding tax for share based compensation	0	1,701
Deferred financing costs charged to additional paid in capital	0	5,230
Warrants issued in connection with long-term debt	6,800	0
Noncash component of warrants exercised	$ 0	$ 12,591