CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities:
Net income	$ 10,154	$ 48,860
Adjustments to reconcile net income to net cash provided by operating activities:
Lower of cost or market reserve adjustment to inventory	2,356	675
Depreciation and amortization	14,291	8,929
Deferred income taxes, net	(381)	2,638
Loss (gain) on disposal of assets	(5)	40
Share-based compensation	5,468	3,767
Unrealized foreign exchange gain	(1,254)	(254)
Changes in operating assets and liabilities:
Accounts receivable, trade	11,182	(23,992)
Prepaid income tax	781
Inventories	(21,614)	(6,357)
Other current assets	(1,489)	(4,845)
Accounts payable	7,805	17,481
Accrued income taxes	(6,926)	3,870
Accrued liabilities	(2,289)	(928)
Net cash provided by operating activities	18,079	49,884
Investing activities:
Maturities of short-term investments	36	2
Purchase of property, plant and equipment	(30,895)	(26,687)
Purchase of land use rights	(5,591)
Proceeds from disposal of equipment	11	170
Deposits and prepaid for equipment	1,444	(3,838)
Purchase of intangible assets	(225)	(251)
Net cash used in investing activities	(35,220)	(30,604)
Financing activities:
Proceeds from issuance of notes payable and long-term debt	26,556
Principal payments of long-term debt and notes payable	(1,093)	(15,911)
Proceeds from line of credit borrowings	79,953
Repayments of line of credit borrowings	(93,953)
Repayments of bank acceptance payable		(307)
Exercise of stock options	53	1,301
Payments of tax withholding on behalf of employees related to share-based compensation	(2,212)	(1,843)
Proceeds from common stock offering, net		21,572
Net cash provided by financing activities	9,304	4,812
Effect of exchange rate changes on cash	1,832	(177)
Net increase (decrease) in cash, cash equivalents and restricted cash	(6,005)	23,915
Cash, cash equivalents and restricted cash at beginning of period	83,948	51,964
Cash, cash equivalents and restricted cash at end of period	77,943	75,879
Cash paid for:
Interest	255	539
Income taxes	7,783	2,226
Non-cash investing and financing activities:
Net change in accounts payable related to property and equipment additions	$ 214	$ 535