CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income (loss)	$ (21,975)	$ 512,218	$ 145,013
Adjustments to reconcile net income (loss) to net cash provided (used) by operating activities:
Depreciation	125,765	119,803	122,135
Amortization	33,937	18,592	10,650
Loss on early extinguishment of debt	0	5,314	0
Deferred income tax expense (benefit)	1,115	6,815	(6,522)
Equity income of unconsolidated entities, net	(186)	(273)	(384)
Dividends from unconsolidated entities	216	125	88
Gain on Sale from discontinued business	(18,281)	(569,135)	0
Other, net	310	1,764	2,666
Changes in assets and liabilities:
Accounts receivable	34,221	(3,464)	(16,881)
Income tax refunds receivable from acquisition, reimbursable to seller	(11,032)	0	0
Insurance receivable	0	195,000	0
Inventories	(12,281)	(42,484)	(14,706)
Contract assets	(28,376)	(21,795)	(3,312)
Right-of-use-assets	25,400	15,164	0
Accounts payable	(14,452)	13,407	18,347
Accrued interest payable	(2,422)	14,723	(154)
Accrued compensation	2,921	(15,759)	(1,127)
Advances on contracts and other customer advances	10,492	(4,172)	3,057
Operating lease liabilities	(24,785)	(14,740)
Insurance liability	0	(195,000)	0
Income taxes payable - gain on sale of discontinued businesses	(12,373)	12,373	0
Retirement plan liabilities, net	(33,257)	(24,022)	(33,321)
Other assets and liabilities	(1,139)	(24,617)	(33,527)
Net cash provided (used) by operating activities	53,818	(163)	192,022
Cash flows from investing activities:
Purchases of property, plant and equipment	(120,224)	(184,973)	(132,168)
Proceeds from sale of businesses	37,219	658,414	0
Purchase of businesses, net of cash acquired*	(432,855)	(623,495)	(56,389)
Proceeds from sales of assets	6,204	17,022	11,887
Expenditures for intangible assets	(317)	(1,311)	0
Purchase of equity method investment	0	(2,364)	0
Payments for interest rate swap terminations	0	(2,758)	0
Net proceeds (payments) from settlement of foreign currency forward exchange contracts	(10,519)	7,273	15,527
Other investing activities, net	(152)	0	0
Net cash used by investing activities	(520,644)	(132,192)	(161,143)
Cash flows from financing activities:
Short-term borrowings, net	1,612	(5,398)	1,932
Current maturities and long-term debt:
Additions	638,717	848,314	128,858
Reductions	(139,887)	(661,620)	(116,988)
Dividends paid to noncontrolling interests	(2,978)	(4,712)	(5,480)
Noncontrolling Interest - purchase or sale	(561)	4,026	477
Stock-based compensation - Employee taxes paid	(4,303)	(11,234)	(3,730)
Common stock acquired for treasury	0	(31,838)	(30,011)
Payment of contingent consideration	(2,342)	0	0
Deferred financing costs	(1,928)	(11,272)	(596)
Other financing activities, net	(1,372)	(532)	0
Net cash provided (used) by financing activities	486,958	125,734	(25,538)
Effect of exchange rate changes on cash, including restricted cash	(195)	(793)	(4,404)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	19,937	(7,414)	937
Cash and cash equivalents, including restricted cash, at beginning of period	59,732	67,146	66,209
Cash and cash equivalents, including restricted cash, at end of period	79,669	59,732	67,146
Supplemental Cash Flow Information [Abstract]
Change in accrual for purchases of property, plant and equipment included in accounts payable	3,559	5,164	7,567
Purchase of businesses, net of cash acquired
Working capital	(33,387)	(26,663)	1,295
Property, plant and equipment	(102,258)	(77,295)	(3,327)
Goodwill	(153,562)	(330,230)	(22,518)
Long-term debt acquired	0	605	335
Other noncurrent assets and liabilities, net	(143,648)	(189,912)	(32,174)
Net cash used to acquire businesses	$ (432,855)	$ (623,495)	$ (56,389)