Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
OPERATING ACTIVITIES
Net income	$ 111,610	$ 96,508	$ 118,768
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	70,374	62,480	65,130
Amortization	6,359	6,569	9,125
Change in deferred taxes and other liabilities	(2,046)	(8,496)	12,181
Impairment of property, plant, equipment, and inventory	1,773	1,808	856
Non-cash interest expense	1,404	1,118	875
Non-cash portion of pension settlement expense	0	42,657	0
Compensation and benefits paid or payable in Class A Common Stock	6,936	4,527	3,146
Provision/(recovery) for credit losses from uncollected receivables and contract assets	640	1,408	(1,299)
Foreign currency remeasurement (gain)/loss on intercompany loans	(2,831)	(4,434)	(3,150)
Fair value adjustment on foreign currency options	(139)	(509)	169
Changes in operating assets and liabilities that provided/(used) cash, net of impact of business acquisition:
Accounts receivable	(11,038)	(14,301)	(7,734)
Contract assets	(32,156)	(36,434)	25,446
Inventories	15,093	(24,541)	(9,942)
Prepaid expenses and other current assets	1,530	(4,134)	(998)
Income taxes prepaid and receivable	(2,897)	(6,005)	3,944
Accounts payable	(5,672)	8,572	9,492
Accrued liabilities	(10,441)	3,226	(774)
Income taxes payable	(1,988)	183	(477)
Noncurrent receivables	3,723	3,911	4,355
Other noncurrent liabilities	(9,783)	(10,133)	(13,713)
Other, net	7,605	4,234	2,075
Net cash provided by operating activities	148,056	128,214	217,475
INVESTING ACTIVITIES
Purchase of business, net of cash acquired	(133,470)	0	0
Purchases of property, plant and equipment	(83,560)	(93,675)	(52,793)
Purchased software	(869)	(2,673)	(906)
Net cash used in investing activities	(217,899)	(96,348)	(53,699)
FINANCING ACTIVITIES
Proceeds from borrowings	78,040	162,000	8,000
Principal payments on debt	(92,274)	(73,000)	(56,009)
Principal payments on finance lease liabilities	0	(654)	(1,438)
Debt acquisition costs	(4,108)	0	0
Purchase of Treasury shares	0	(84,780)	(23,449)
Taxes paid in lieu of share issuance	(3,136)	(770)	(998)
Proceeds from options exercised	0	17	153
Dividends paid	(31,163)	(26,465)	(25,894)
Net cash used in financing activities	(52,641)	(23,652)	(99,635)
Effect of exchange rate changes on cash and cash equivalents	4,128	(18,474)	(3,421)
Increase/(decrease) in cash and cash equivalents	(118,356)	(10,260)	60,720
Cash and cash equivalents at beginning of period	291,776	302,036	241,316
Cash and cash equivalents at end of period	$ 173,420	$ 291,776	$ 302,036