Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net loss	$ (35,278)	$ (35,998)
Adjustments to reconcile net loss to net cash used in operating activities:
Provision for uncollectible accounts	287	419
Write-downs of excess and obsolete inventories	753	349
Depreciation and amortization	1,374	1,172
Debt related amortization included in interest expense	798	491
Stock-based compensation	1,908	1,711
Changes in operating assets and liabilities:
Trade accounts receivable	(806)	(3,917)
Inventories	(251)	1,874
Prepaid expenses and other current assets	(409)	(758)
Accounts payable and other current liabilities	(837)	(5,870)
Accrued compensation	1,017	1,304
Other long-term liabilities	35	(24)
Net cash used in operating activities	(31,409)	(39,247)
Cash flows from investing activities:
Acquisition of property, plant and equipment	(533)	(875)
Net cash used in investing activities	(533)	(875)
Cash flows from financing activities:
Borrowings under credit facility, net	16,711	12,500
Proceeds from the sale of common stock	88,816
Payments of financing costs related to issuance of common stock	(283)
Proceeds from the exercise of stock options	397	1,322
Payment of debt issuance costs and other financing activities	(6)	121
Net cash provided by financing activities	105,635	13,943
Net increase (decrease) in cash and cash equivalents	73,693	(26,179)
Cash and cash equivalents, beginning of period	28,165	63,710
Cash and cash equivalents, end of period	101,858	37,531
Supplemental Disclosure of Cash Flow Information:
Income taxes paid	16	9
Interest paid	2,086	1,579
Acquisition of property, plant and equipment accrued not paid	53	(8)
Financing costs related to the issuance of common stock accrued not paid	$ 122