Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
OPERATING ACTIVITIES
Net income	$ 28,075	$ 27,609
Adjustments to reconcile net income to net cash (used in)/provided by operating activities:
Depreciation	15,597	16,589
Amortization	2,165	2,293
Change in deferred taxes and other liabilities	1,792	4,442
Impairment of property, plant, equipment, and inventory	2,868	185
Non-cash interest expense	282	45
Compensation and benefits paid or payable in Class A Common Stock	745	(13)
Provision for credit losses from uncollected receivables and contract assets	1,858	(110)
Foreign currency remeasurement (gain)/loss on intercompany loans	(2,385)	(308)
Fair value adjustment on foreign currency options	(977)	139
Changes in operating assets and liabilities that (used)/provided cash:
Accounts receivable	(15,674)	(3,236)
Contract assets	272	16,104
Inventories	(7,549)	(8,563)
Prepaid expenses and other current assets	(1,976)	(899)
Income taxes prepaid and receivable	1,829	(1,465)
Accounts payable	(375)	9,188
Accrued liabilities	(19,350)	(19,485)
Income taxes payable	(10,890)	(8,077)
Noncurrent receivables	614	488
Other noncurrent liabilities	(1,914)	(2,097)
Other, net	(398)	857
Net cash (used in)/provided by operating activities	(5,391)	33,686
INVESTING ACTIVITIES
Purchases of property, plant and equipment	(15,719)	(12,534)
Purchased software	(35)	(2)
Net cash used in investing activities	(15,754)	(12,536)
FINANCING ACTIVITIES
Proceeds from borrowings	77,000	8,000
Principal payments on debt	0	(22,007)
Principal payments on finance lease liabilities	(390)	(349)
Purchase of Treasury shares	(42,230)	0
Taxes paid in lieu of share issuance	(770)	(998)
Proceeds from options exercised	7	128
Dividends paid	(6,742)	(6,468)
Net cash provided by/(used in) financing activities	26,875	(21,694)
Effect of exchange rate changes on cash and cash equivalents	(351)	(2,901)
Increase/(decrease) in cash and cash equivalents	5,379	(3,445)
Cash and cash equivalents at beginning of period	302,036	241,316
Cash and cash equivalents at end of period	$ 307,415	$ 237,871