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 loss	$ (17,076)	$ (43,637)	$ (53,333)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	30,788	31,105	28,350
Stock-based compensation expense	12,456	14,142	8,206
Deferred taxes	(287)	(328)	792
Amortization of investment, debt and other	414	438	247
Loss (gain) on disposal of property and equipment	(872)	1,322	(1,746)
Amortization of operating lease right-of-use assets	1,774	0	0
Loss (gain) on foreign currency hedges	0	2,220	(2,104)
Allowance for doubtful accounts	(13)	61	577
Write-down of inventories	7,847	6,133	8,349
Foreign currency remeasurement and other, net	(910)	(3,944)	2,583
Issuance of common stock in exchange for research and development services	2,500	0	0
Asset impairment charges	0	0	324
Change in assets and liabilities:
Accounts receivable	5,838	(7,874)	13,166
Inventories	(2,891)	7,368	(22,347)
Prepaid expenses and other assets	429	8,162	(11,409)
Accounts payable	(41)	(1,411)	(10,874)
Accrued and other liabilities	(5,269)	5,838	6,452
Net cash provided by (used in) operating activities	34,687	19,595	(32,767)
Cash flows from investing activities
Purchase of property, plant and equipment	(9,532)	(14,867)	(47,409)
Proceeds from sale of property, plant and equipment and other assets	2,242	32	21,809
Purchase of marketable securities	(157)	(920)	(52,062)
Proceeds from sale of marketable securities	0	5,000	52,272
Proceeds from maturity of marketable securities	0	750	6,458
Settlement of foreign currency hedges	0	(1,776)	1,618
Net cash used in investing activities	(7,447)	(11,781)	(17,314)
Cash flows from financing activities
Proceeds from exercise of stock options and issuance of stock under ESPP	3,846	5,614	4,893
Offering costs	(46)	0	0
Tax withholding on restricted stock units	(733)	(954)	(998)
Payments for public stock offering, net of offering costs	0	0	(117)
Proceeds from bank loans	5,000	34,305	112,834
Repayment of bank loans	(18,084)	(63,040)	(68,492)
Proceeds from issuance of notes payable	0	7,137	6,621
Repayment of finance lease liabilities	(87)	0	0
Repayment of notes payable	(4,774)	(3,732)	(11,639)
Proceeds from government grants	0	1,210	0
Net cash (used in) provided by financing activities	(14,878)	(19,460)	43,102
Effect of exchange rates on cash, cash equivalents and restricted cash	(161)	(680)	1,958
Net increase (decrease) in cash, cash equivalents and restricted cash	12,201	(12,326)	(5,021)
Cash, cash equivalents and restricted cash at the beginning of the period	69,238	81,564	86,585
Cash, cash equivalents and restricted cash at the end of the period	81,439	69,238	81,564
Supplemental disclosure of cash flow information:
Cash paid for interest	278	1,600	732
Net cash paid (received) for income taxes	1,289	(1,383)	5,388
Supplemental disclosure of noncash investing and financing activities:
Neo Russia penalty settlement	2,000	0	0
Debt interest rolled into principal	1,368	0	0
Government approved expenditures incurred after receipt of government funds	579	0	0
Decrease (increase) in unpaid property, plant and equipment	(374)	8,548	6,072
Capital lease	0	362	0
Asset retirement obligation	$ 0	$ 0	$ 2,146