Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
OPERATING ACTIVITIES
Net income	$ 39,369	$ 31,440	$ 67,444	$ 59,050
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	15,679	15,971	31,276	32,560
Amortization	1,433	2,280	3,598	4,573
Change in deferred taxes and other liabilities	804	974	2,596	5,416
Impairment of property, plant, equipment, and inventory	(206)	353	2,662	538
Non-cash interest expense	279	265	561	310
Compensation and benefits paid or payable in Class A Common Stock	1,702	1,639	2,447	1,626
Provision for credit losses from uncollected receivables and contract assets	(532)	27	1,326	(83)
Foreign currency remeasurement (gain)/loss on intercompany loans	1,125	(723)	(1,260)	(1,031)
Fair value adjustment on foreign currency options	596	1	(381)	140
Changes in operating assets and liabilities that provided/(used) cash:
Accounts receivable	1,267	(129)	(14,407)	(3,365)
Contract assets	(24,140)	9,539	(23,868)	25,643
Inventories	(13,586)	(1,821)	(21,135)	(10,384)
Prepaid expenses and other current assets	(2,498)	(606)	(4,474)	(1,505)
Income taxes prepaid and receivable	(1,889)	1,156	(60)	(309)
Accounts payable	7,851	(4,580)	7,476	4,608
Accrued liabilities	7,605	2,062	(11,745)	(17,423)
Income taxes payable	3,151	4,121	(7,739)	(3,956)
Noncurrent receivables	1,250	1,099	1,864	1,587
Other noncurrent liabilities	(1,338)	(2,166)	(3,252)	(4,263)
Other, net	5,182	1,051	4,784	1,908
Net cash provided by operating activities	43,104	61,953	37,713	95,640
INVESTING ACTIVITIES
Purchases of property, plant and equipment	(19,940)	(10,302)	(35,659)	(22,836)
Purchased software	(331)	(286)	(366)	(288)
Net cash used in investing activities	(20,271)	(10,588)	(36,025)	(23,124)
FINANCING ACTIVITIES
Proceeds from borrowings	58,000	0	135,000	8,000
Principal payments on debt	0	(34,002)	0	(56,009)
Principal payments on finance lease liabilities	(264)	(355)	(654)	(704)
Purchase of Treasury shares	(42,550)	0	(84,780)	0
Taxes paid in lieu of share issuance	0	0	(770)	(998)
Proceeds from options exercised	0	21	7	149
Dividends paid	(6,657)	(6,474)	(13,399)	(12,942)
Net cash provided by/(used in) financing activities	8,529	(40,810)	35,404	(62,504)
Effect of exchange rate changes on cash and cash equivalents	(17,907)	4,904	(18,258)	2,002
Increase in cash and cash equivalents	13,455	15,459	18,834	12,014
Cash and cash equivalents at beginning of period	307,415	237,871	302,036	241,316
Cash and cash equivalents at end of period	$ 320,870	$ 253,330	$ 320,870	$ 253,330