CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income (loss)	$ 16,645	$ (8,228)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation	64,904	61,512
Amortization	17,783	15,672
Deferred income tax benefit	(6,407)	(655)
Equity (income) loss of unconsolidated entities, net	195	(167)
Gain on sale from discontinued business	0	(18,371)
Loss on early extinguishment of debt	2,668	0
Other, net	(2,149)	(2,244)
Changes in assets and liabilities, net of acquisitions and dispositions of businesses:
Accounts receivable	(23,484)	16,534
Inventories	15,456	(16,666)
Contract assets	(37,866)	(28,934)
Right-of-use assets	13,897	11,834
Accounts payable	(13,491)	(8,119)
Accrued interest payable	(137)	(2,940)
Accrued compensation	4,701	(4,767)
Advances on contracts	(13,351)	35,836
Operating lease liabilities	(13,506)	(11,596)
Retirement plan liabilities, net	(27,858)	(19,026)
Income taxes payable - Gain on sale of discontinued businesses	0	3,467
Other assets and liabilities	15,530	(1,621)
Net cash provided by operating activities	13,530	21,521
Cash flows from investing activities:
Purchases of property, plant and equipment	(68,646)	(51,213)
Purchases of businesses, net of cash acquired	0	(442,604)
Proceeds from Divestiture of Businesses	0	37,219
Proceeds from sales of assets	10,042	3,952
Expenditures for intangible assets	(132)	(42)
Proceeds from notes receivable	6,400	0
Net proceeds (payments) from settlement of foreign currency forward exchange contracts	(978)	765
Other investing activities, net	133	59
Net cash used by investing activities	(53,181)	(451,864)
Cash flows from financing activities:
Short-term borrowings, net	4,444	2,677
Current maturities and long-term debt:
Additions	465,518	528,601
Reductions	(413,481)	(62,406)
Dividends paid to noncontrolling interests	(3,094)	0
Stock-based compensation - Employee taxes paid	(3,172)	(4,093)
Deferred financing costs	(7,828)	(1,928)
Other financing activities, net	(601)	(1,371)
Net cash provided by financing activities	41,786	461,480
Effect of exchange rate changes on cash and cash equivalents, including restricted cash	483	(6,818)
Net increase in cash and cash equivalents, including restricted cash	2,618	24,319
Cash and cash equivalents, including restricted cash, at beginning of period	79,669	59,732
Cash and cash equivalents, including restricted cash, at end of period	82,287	84,051
Supplemental Cash Flow Information [Abstract]
Change in accrual for purchases of property, plant and equipment included in accounts payable	$ 2,158	$ 1,085