Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (7,475)	$ (1,235)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,769	1,565
Amortization	1,392	647
Reduction in carrying amount of right-of-use assets	706
Provision for losses on accounts receivable	67	28
Stock-based compensation	3,763	1,909
(Gain) loss on disposal of assets	(1)	5
Changes in operating assets and liabilities:
Accounts receivable, net	(53)	(3,582)
Inventory	(3,572)	(6,072)
Prepaid expenses and other current assets	923	1,500
Other assets	(1,488)	(588)
Accounts payable	4,582	2,113
Accrued and other long-term liabilities	(2,247)	(996)
Deferred revenues	1,312	(578)
Operating lease liabilities	(705)
Non-current income taxes payable	(52)	345
Net cash used in operating activities	(1,079)	(4,939)
Cash flows from investing activities:
Purchases of property, plant and equipment	(15,185)	(2,284)
Capitalization of patents	(320)	(450)
Proceeds from sale of assets	41	0
Net cash used in investing activities	(15,464)	(2,734)
Cash flows from financing activities:
Principal payments on debt and capital leases	(16)	(25)
Net proceeds from debt financing	15,000	0
Proceeds from stock option exercises	558	467
Tax payments related to stock award issuances	(11)	0
Net cash provided by financing activities	15,531	442
Effect of exchange rate changes on cash	10	119
Net decrease in cash and cash equivalents	(1,002)	(7,112)
Cash and cash equivalents, beginning of period	117,252	149,478
Cash and cash equivalents, end of period	116,250	142,366
Supplemental disclosures:
Cash received for interest	384	769
Cash paid for income taxes	605	813
Accrued purchases of property, equipment and patents	744	$ 835
Supplemental disclosures of noncash investing and financing activities:
Right-of-use assets obtained for operating leases	$ 7,566