Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ (12,884)	$ 13,938	$ 1,837
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation	6,583	5,867	5,352
Amortization	2,981	2,421	2,570
Provision for losses on accounts receivable	83	22	232
Stock-based compensation	9,730	4,805	369
Deferred income taxes	3,041	(1,307)	(424)
Loss (gain) on disposal of assets	(483)	12	9
Loss on debt extinguishment	0	12	911
Changes in operating assets and liabilities:
Accounts receivable, net	(395)	(13,734)	(3,523)
Inventory	(10,670)	(6,145)	(9,875)
Prepaid expenses and other current assets	(111)	(2,483)	(639)
Other assets	(2,669)	(2,262)	(1,148)
Accounts payable	844	172	2,491
Accrued and other long-term liabilities	92	(310)	3,160
Deferred revenues	(178)	(215)	731
Non-current income taxes payable	(205)	2,542	1,358
Net cash provided by (used in) operating activities	(4,241)	3,335	3,411
Cash flows from investing activities:
Acquisition of business, net of cash acquired	(17,400)	0	0
Purchases of property, equipment and patents	(13,632)	(11,714)	(5,483)
Proceeds from sale of assets	628	35	6
Net cash used in investing activities	(30,404)	(11,679)	(5,477)
Cash flows from financing activities:
Principal payments on debt and capital leases	(55)	(33,417)	(15,318)
Net proceeds from debt financing	0	16,053	12,499
Cash paid on debt extinguishment	0	0	(388)
Proceeds from public offerings, net of offering costs	0	138,303	0
Proceeds from issuance of convertible preferred stock	0	0	27,481
Proceeds from employee stock plan purchases	1,471	0	0
Payments of other financing costs	0	0	(191)
Proceeds from stock option exercises	1,560	362	336
Tax payments related to stock award issuances	(524)	0	0
Net cash provided by financing activities	2,452	121,301	24,419
Effect of exchange rate changes on cash	(33)	(166)	834
Net increase (decrease) in cash and cash equivalents	(32,226)	112,791	23,187
Cash and cash equivalents, beginning of period	149,478	36,687	13,500
Cash and cash equivalents, end of period	117,252	149,478	36,687
Supplemental disclosures:
Cash paid (received) for interest	(2,802)	941	1,437
Cash paid for income taxes	2,335	3,665	3,493
Accrued purchases of property, equipment and patents	828	577	969
Accrued deferred offering costs	$ 0	$ 0	$ 530