Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities:
Net income (loss)	$ (66,049)	$ (2,146)	$ 73,951
Adjustments to reconcile net income to net cash provided by operating activities:
Lower of cost or market reserve adjustment to inventory	6,774	7,166	1,866
Depreciation and amortization	24,014	29,698	20,381
Amortization of debt issuance costs	892	42	81
Deferred income taxes, net	14,570	(8,964)	(114)
Loss on disposal of assets	13	7	97
Share-based compensation	11,804	11,120	7,795
Unrealized foreign exchange gain (loss)	(245)	(548)	330
Changes in operating assets and liabilities:
Accounts receivable, trade	(4,355)	29,316	(10,080)
Prepaid income tax	961	230	(1,386)
Inventories	1,560	(28,403)	(21,876)
Other current assets	5,514	(2,939)	(4,266)
Operating right of use asset	847	0	0
Accounts payable	3,150	(13,714)	7,249
Accrued income taxes	0	(7,390)	6,204
Accrued liabilities	(308)	554	4,052
Lease liability	(896)	0	0
Net cash provided (used in) by operating activities	(1,754)	14,029	84,284
Investing activities:
Maturities of short-term investments	0	36	8
Purchase of property, plant and equipment	(28,789)	(71,854)	(66,968)
Purchase of land use rights	0	(5,591)	0
Proceeds from disposal of equipment	1	697	171
Deposits and prepaid for equipment	(2,688)	674	(2,871)
Purchase of intangible assets	(640)	(476)	(499)
Net cash used in investing activities	(32,116)	(76,514)	(70,159)
Financing activities:
Proceeds from issuance of notes payable and long-term debt, net of debt issuance costs	13,661	47,849	0
Principal payments of long-term debt and notes payable	(43,363)	(3,133)	(42,758)
Proceeds from line of credit borrowings	83,434	155,078	88,003
Repayments of line of credit borrowings	(88,299)	(165,569)	(39,003)
Proceeds from bank acceptance payable	13,638	4,595	0
Repayments of bank acceptance payable	(11,952)	0	(309)
Proceeds from issuance of convertible senior notes, net of debt issuance costs	76,362	0	0
Principal payments of financing lease	(2)
Exercise of stock options	14	120	1,460
Payments of tax withholding on behalf of employees related to share-based compensation	(897)	(4,137)	(10,721)
Proceeds from common stock offering, net	0	0	21,572
Net cash provided by financing activities	42,596	34,803	18,244
Effect of exchange rate changes on cash	298	1,738	(385)
Net increase (decrease) in cash, cash equivalents and restricted cash	9,024	(25,944)	31,984
Cash, cash equivalents and restricted cash at beginning of period	58,004	83,948	51,964
Cash, cash equivalents and restricted cash at end of period	67,028	58,004	83,948
Supplemental disclosure of cash flow information:
Interest	3,172	848	872
Income taxes	(890)	8,470	5,835
Non-cash investing and financing activities:
Net change in accounts payable related to property and equipment additions	(3,869)	(1,151)	4,582
Net change in deposits and prepaid for equipment related to property and equipment additions	$ 8,801	$ 0	$ 0