Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (22,311)	$ (24,360)
Adjustments to reconcile net loss to net cash used in operating activities:
Provision for uncollectible accounts	122	215
Write-downs of excess and obsolete inventories	335	203
Depreciation and amortization	903	755
Debt related amortization included in interest expense	533	327
Stock-based compensation	1,254	1,105
Changes in operating assets and liabilities:
Trade accounts receivable	716	(2,064)
Inventories	(74)	1,488
Prepaid expenses and other current assets	(781)	(693)
Accounts payable and other current liabilities	(904)	(7,161)
Accrued compensation	356	1,220
Other long-term liabilities	45	269
Net cash used in operating activities	(19,806)	(28,696)
Cash flows from investing activities:
Acquisition of property, plant and equipment	(407)	(614)
Net cash used in investing activities	(407)	(614)
Cash flows from financing activities:
Borrowings under credit facility, net	11,711
Proceeds from the sale of common stock	24,046
Payments of financing costs related to issuance of common stock	(246)
Proceeds from the exercise of stock options	231	66
Payment of debt issuance costs and other financing activities		(42)
Net cash provided by financing activities	35,742	24
Net increase (decrease) in cash and cash equivalents	15,529	(29,286)
Cash and cash equivalents, beginning of period	28,165	63,710
Cash and cash equivalents, end of period	43,694	34,424
Supplemental Disclosure of Cash Flow Information:
Income taxes paid
Interest paid	1,523	603
Acquisition of property, plant and equipment accrued not paid		$ 18