CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net income (loss)	$ (36,622)	$ (8,036)	$ 56,708
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities
Depreciation and amortization	16,684	15,000	14,239
Provision for severance benefits	5,333	6,289	8,282
Amortization of debt issuance costs and original issue discount			261
Loss on foreign currency, net	3,373	19,729
Provision for inventory reserves	3,885	9,574	2,244
Stock-based compensation	7,223	6,037	7,704
Loss on early extinguishment of borrowings			32,432
Deferred income taxes	(13,405)	278	918
Other, net	757	664	(613)
Changes in operating assets and liabilities
Accounts receivable, net	1,909	10,276	7,505
Inventories	2,370	(12,626)	(5,939)
Other receivables	3,847	18,146	(21,538)
Prepaid expenses	8,808	8,923	8,004
Other current assets	8,048	(13,073)	4,393
Accounts payable	7,152	(16,325)	(11,437)
Other accounts payable	(8,934)	(9,410)	(7,798)
Accrued expenses	493	(7,228)	4,637
Accrued income taxes	(1,569)	(8,400)	(1)
Deferred revenue	85	(1,261)	(131)
Other current liabilities	(109)	(645)	1,445
Other non-current liabilities	(238)	749	(1,398)
Contributions to severance insurance deposit accounts	(5,101)	(7,899)	(5,688)
Payment of severance benefits	(6,982)	(6,012)	(6,679)
Other, net	(21)	415	193
Net cash provided by (used in) operating activities	(3,014)	5,165	87,743
Cash flows from investing activities
Proceeds from settlement of hedge collateral	5,669	15,232	5,214
Payment of hedge collateral	(3,754)	(15,282)	(3,349)
Proceeds from disposal of property, plant and equipment	0	550	1,446
Purchase of property, plant and equipment	(6,955)	(23,394)	(32,212)
Payment for intellectual property registration	(263)	(390)	(614)
Collection of guarantee deposits	4,984	737	3,192
Payment of guarantee deposits	(7,338)	(2,381)	(5,001)
Other, net			(114)
Net cash used in investing activities	(7,657)	(24,928)	(31,438)
Cash flows from financing activities
Proceeds from exercise of stock options	27	1,786	4,279
Acquisition of treasury stock	(51,782)	(13,960)	(1,653)
Acquisition of stock under accelerated stock repurchase agreement			(20,073)
Payment under accelerated stock repurchase agreement			(17,427)
Repayment of financing related to water treatment facility arrangement	(493)	(500)	(563)
Others	(91)	(70)	(107)
Net cash used in financing activities	(52,339)	(12,744)	(35,544)
Effect of exchange rates on cash and cash equivalents	(4,375)	(21,563)	(21,154)
Net decrease in cash and cash equivalents	(67,385)	(54,070)	(393)
Cash and cash equivalents at beginning of period	225,477	279,547	279,940
Cash and cash equivalents at end of period	158,092	225,477	279,547
Supplemental cash flow information
Cash paid for interest			2,094
Cash paid for income taxes, net	1,442	18,988	12,672
Non-cash investing and financing activities
Property, plant and equipment additions in other accounts payable	42	190	747
Acquisition of treasury stock to satisfy the tax withholding obligations in connection with equity-based compensation	$ 544	387	826
Unsettled common stock repurchases		$ 378
Exchange of exchangeable senior notes into common stock			$ 83,740