CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows (used in) provided by operating activities:
Net (loss) income	$ (1,010)	$ (1,412)	$ 34,041
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation	11,303	9,632	8,316
Amortization of purchased intangible assets	1,391	1,449	1,544
Amortization and write-off of deferred debt issuance costs	248	207	178
Stock-based compensation	6,574	5,675	5,204
Deferred income taxes	(1,846)	(2,313)	4,289
(Gain) loss on disposal of property, plant and equipment	(204)	247	530
Restructuring expenses, net and asset impairments	127	3,387	19,503
Change in:
Accounts receivable, net	(9,769)	30,227	(1,221)
Inventories	(12,440)	2,992	(2,671)
Prepaid expenses and other	(19,413)	675	(5,724)
Accounts payable	13,584	(14,772)	10,145
Contract liabilities	1,613	1,985	1,603
Accrued anti-dumping duties and penalties	0	0	(8,000)
Accrued expenses and other liabilities	(2,970)	(7,617)	(3,143)
Net cash (used in) provided by operating activities	(12,812)	30,362	64,594
Cash flows used in investing activities:
Acquisition of business, net of cash acquired	(261,000)	0	0
Investment in marketable securities	(123,984)	(25,740)	0
Proceeds from maturities of marketable securities	4,799	0	0
Proceeds from sales of marketable securities	144,921	0	0
Acquisition of property, plant and equipment	(8,659)	(13,853)	(27,210)
Promissory note to redeemable noncontrolling interest holder	(24,902)	0	0
Proceeds on sale of property, plant and equipment	1,019	36	1,263
Net cash used in investing activities	(267,806)	(39,557)	(25,947)
Cash flows provided by (used in) financing activities:
Payments on revolving loans, net	0	0	(17,129)
Payments on capital expenditure facility	(11,750)	(3,125)	(10,125)
Borrowings on term loan	150,000	0	0
Payment of dividends	0	(3,749)	(2,762)
Payment of deferred debt issuance costs	(2,337)	(90)	0
Net proceeds from issuance of common stock to employees and directors	434	431	557
Treasury stock purchases	(2,485)	(1,890)	(1,103)
Net cash provided by (used in) financing activities	282,585	17,317	(30,562)
Effects of exchange rates on cash	656	(288)	(1,107)
Net increase in cash and cash equivalents	2,623	7,834	6,978
Cash and cash equivalents, beginning of the period	28,187	20,353	13,375
Cash and cash equivalents, end of the period	30,810	28,187	20,353
Supplemental disclosures of noncash investing and financing activities:
Non-cash consideration for acquisition of business, net of cash acquired	21,716	0	0
Non-cash lease liabilities arising from obtaining right-of-use assets	0	0	8,821
Cash paid during the period for -
Interest	51	402	1,445
Income taxes, net	7,533	497	20,995
Equity Offering
Cash flows provided by (used in) financing activities:
Net proceeds from issuance of common stock through at-the-market offering program	123,461	0	0
ATM Offering
Cash flows provided by (used in) financing activities:
Net proceeds from issuance of common stock through at-the-market offering program	$ 25,262	$ 25,740	$ 0