Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Statement Of Cash Flows [Abstract]
Net cash flows (used in) provided by operating activities	$ (4,398)	$ 33,944
Cash flows from investing activities:
Purchases of property, plant and equipment	(11,982)	(6,015)
Proceeds from sale of property, plant and equipment	249	30
Purchases of long-term marketable securities	(31)	(146)
Proceeds from sale of long-term marketable securities	243	349
Net cash flows used in investing activities	(11,521)	(5,782)
Cash flows from financing activities:
Repayment of debt	(1,730)	(976)
Proceeds from revolving credit facility	19,016	0
Payments on revolving credit facility	(8,500)	(34,273)
Proceeds from shareholder exercise of warrants (Note 9)	3,308	0
Proceeds from equity rights offering, net of issuance costs (Note 9)	0	18,150
Debt issuance costs	(485)	(329)
Net cash flows provided by (used in) financing activities	11,609	(17,428)
Effect of exchange rate changes on cash and cash equivalents	(281)	586
Net (decrease) increase in cash and cash equivalents	(4,591)	11,320
Cash and cash equivalents at beginning of period	16,842	6,960
Cash and cash equivalents at end of period	12,251	18,280
Supplemental information:
Income tax payments	1,344	1,597
Interest payments	1,810	2,287
Non-cash investing and financing activities:
Purchases of property, plant and equipment in current liabilities	1,339	945
Finance lease right-of-use assets exchanged for lease liabilities	1,250	423
Operating lease right-of-use assets exchanged for lease liabilities	$ 53	$ 691