Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities
Net loss	$ (21,417)	$ (28,783)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	16,942	15,911
Stock-based compensation expense	6,343	6,486
Deferred taxes	0	(42)
Others	216	214
Loss (gain) on sale of assets and other write-offs	(541)	43
Loss on foreign currency hedges	0	1,005
Allowance for doubtful accounts	(8)	(101)
Write-down of inventories	5,479	1,857
Amortization of operating lease right-of-use assets	872	0
Foreign currency remeasurement	614	(1,123)
Change in assets and liabilities, net of effects of asset sale:
Accounts receivable	15,163	(9,981)
Inventories	(2,103)	4,173
Prepaid expenses and other assets	3,053	5,565
Accounts payable	(6,933)	94
Accrued and other liabilities	(8,247)	148
Net cash provided by (used in) operating activities	9,433	(4,534)
Cash flows from investing activities
Purchase of property, plant and equipment	(4,042)	(10,653)
Proceeds from sale of property, plant and equipment and other assets	1,986	15
Purchase of marketable securities	(86)	(840)
Proceeds from maturity of marketable securities	0	750
Settlement of foreign currency hedges	0	1,003
Net cash used in investing activities	(2,142)	(9,725)
Cash flows from financing activities
Proceeds from exercise of stock options and issuance of stock under ESPP	1,807	1,933
Tax withholding on restricted stock units	(327)	(276)
Proceeds from bank loans, net of debt issuance costs	5,000	24,419
Repayment of bank loans	(11,529)	(39,603)
Proceeds from issuance of notes payable	0	2,039
Repayment of notes payable	(4,860)	(1,676)
Repayment of finance lease liabilities	(46)	0
Proceeds from government grants	0	1,257
Net cash used in financing activities	(9,955)	(11,907)
Effect of exchange rates on cash, cash equivalents and restricted cash	66	(176)
Net decrease in cash, cash equivalents and restricted cash	(2,598)	(26,342)
Cash, cash equivalents and restricted cash at the beginning of the period	69,238	81,564
Cash, cash equivalents and restricted cash at the end of the period	66,640	55,222
Supplemental disclosure of non-cash investing and financing activities:
Decrease (increase) in unpaid property, plant and equipment	$ (1)	$ 6,943