Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities
Net income (loss)	$ 6,307	$ (14,091)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	6,674	8,851
Stock-based compensation expense	2,518	3,338
Deferred taxes	1,214	0
Others	86	109
Loss (gain) on sale of assets and other write-offs	(25)	85
Write-down of inventories	3,011	764
Amortization of operating lease right-of-use assets	462	432
Foreign currency remeasurement	(1,118)	1,818
Change in assets and liabilities:
Accounts receivable	7,209	9,675
Inventories	(2,699)	(1,654)
Prepaid expenses and other assets	(469)	2,804
Accounts payable	523	(1,232)
Accrued and other liabilities	1,233	(2,200)
Net cash provided by operating activities	24,926	8,699
Cash flows from investing activities
Purchase of property, plant and equipment	(2,578)	(3,600)
Proceeds from sale of property, plant and equipment and other assets	109	4
Purchase of marketable securities	(24)	(43)
Net cash used in investing activities	(2,493)	(3,639)
Cash flows from financing activities
Proceeds from exercise of stock options and issuance of stock under ESPP	231	157
Tax withholding on restricted stock units	(219)	(82)
Proceeds from bank loans, net of debt issuance costs	0	5,000
Repayment of bank loans	(1,772)	(5,764)
Repayment of notes payable	0	(2,559)
Repayment of finance lease liabilities	(21)	(33)
Net cash used in financing activities	(1,781)	(3,281)
Effect of exchange rates on cash, cash equivalents and restricted cash	(254)	353
Net increase in cash, cash equivalents and restricted cash	20,398	2,132
Cash, cash equivalents and restricted cash at the beginning of the period	81,439	69,238
Cash, cash equivalents and restricted cash at the end of the period	101,837	71,370
Supplemental disclosure of non-cash investing and financing activities:
Unpaid property, plant and equipment in accounts payable	$ 1,130	$ 1,887