CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net income (loss)	$ (88,098)	$ (176,431)	$ 2,729
Adjustments to reconcile net income (loss) to net cash provided (used) by operating activities:
Depreciation	138,956	129,712	131,449
Amortization	32,408	34,137	35,224
(Gain) loss on early extinguishment of debt	0	(2,254)	2,668
Deferred income tax expense (benefit)	1,066	(12,029)	(16,930)
Equity (income) loss of unconsolidated entities, net	761	178	302
Dividends from unconsolidated entities	0	526	269
Goodwill and other intangible asset impairment charges	0	119,580	0
Property, plant and equipment impairment charge	14,099	0	0
Other, net	10,167	(427)	2,062
Changes in assets and liabilities:
Accounts receivable	(38,889)	94,317	(19,781)
Income tax refunds receivable from acquisition, reimbursable to seller	0	7,687	2,870
Inventories	(3,410)	(16,798)	(7,783)
Contract assets	3,475	11,543	(43,510)
Right-of-use-assets	32,479	29,171	28,300
Accounts payable	(5,090)	19,264	14,118
Accrued interest payable	221	(643)	(411)
Accrued compensation	33,871	(3,945)	6,469
Advances on contracts and other customer advances	(14,160)	(11,347)	(14,311)
Operating lease liabilities	(30,698)	(28,374)	(27,307)
Retirement plan liabilities, net	(3,968)	(34,136)	(45,786)
Other assets and liabilities	31,258	(9,204)	21,556
Net cash provided (used) by operating activities	114,448	150,527	72,197
Cash flows from investing activities:
Purchases of property, plant and equipment	(139,025)	(137,160)	(158,326)
Purchase of businesses, net of cash acquired*	0	0	0
Proceeds from sales of assets	6,991	10,759	16,724
Expenditures for intangible assets	(503)	(184)	(358)
Proceeds from notes receivable	11,238	8,605	6,400
Payments for settlement of interest rate swaps	0	(2,304)	0
Net proceeds (payments) from settlement of foreign currency forward exchange contracts	4,251	20,950	10,940
Other investing activities, net	463	273	171
Net cash used by investing activities	(116,585)	(99,061)	(124,449)
Cash flows from financing activities:
Short-term borrowings, net	7,027	884	935
Current maturities and long-term debt:
Additions	201,997	224,445	540,663
Reductions	(164,475)	(256,310)	(464,848)
Dividends paid to noncontrolling interests	(5)	(4,841)	(3,103)
Sale of noncontrolling interests	0	1,901	0
Contributions from noncontrolling interests	1,654	0	0
Stock-based compensation - Employee taxes paid	(1,426)	(1,949)	(3,392)
Payment of contingent consideration	0	(6,915)	(1,588)
Deferred financing costs	0	0	(7,828)
Other financing activities, net	0	0	(601)
Net cash (used) provided by financing activities	44,772	(42,785)	60,238
Effect of exchange rate changes on cash, including restricted cash	(3,115)	(10,715)	(527)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	39,520	(2,034)	7,459
Cash and cash equivalents, including restricted cash, at beginning of period	85,094	87,128	79,669
Cash and cash equivalents, including restricted cash, at end of period	124,614	85,094	87,128
Supplemental Cash Flow Information [Abstract]
Change in accrual for purchases of property, plant and equipment included in accounts payable	(7,579)	10,845	4,253
Purchase of businesses, net of cash acquired
Working capital	0	0	532
Property, plant and equipment	0	0	823
Goodwill	0	0	(1,232)
Other noncurrent assets and liabilities, net	0	0	(123)
Net cash used to acquire businesses	$ 0	$ 0	$ 0