Discontinued Operations - Assets and Liabilities Held for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contract assets	$ 1,012,109	$ 859,675
Other accrued liabilities	536,909	402,483
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net	235,697	298,377
Contract assets	159,579	110,340
Other current assets	66,263	119,002
Current assets held for sale	461,539	527,719
PP&E, net	98,703	164,638
Goodwill	118,710	141,889
Investments	3,522	4,649
Other assets	136,141	149,231
Noncurrent assets held for sale	357,076	460,407
Total assets held for sale	818,615	988,126
Accounts payable	104,603	133,981
Short-term borrowings	17,953	20,525
Contract liabilities	40,204	47,779
Accrued salaries, wages and benefits	61,672	64,778
Other accrued liabilities	222,748	125,942
Current liabilities held for sale	447,180	393,005
Noncurrent liabilities held for sale	89,729	108,418
Total liabilities held for sale	536,909	501,423
Discontinued Operations | Stork
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net	196,104	245,105
Contract assets	159,579	108,152
Other current assets	44,638	45,384
Current assets held for sale	400,321	398,641
PP&E, net	94,686	97,258
Goodwill	118,710	141,889
Investments	3,522	4,649
Other assets	120,826	135,421
Noncurrent assets held for sale	337,744	379,217
Total assets held for sale	738,065	777,858
Accounts payable	97,651	116,580
Short-term borrowings	17,953	20,525
Contract liabilities	40,194	46,997
Accrued salaries, wages and benefits	60,573	57,626
Other accrued liabilities	175,220	113,965
Current liabilities held for sale	391,591	355,693
Noncurrent liabilities held for sale	82,961	98,940
Total liabilities held for sale	474,552	454,633
Discontinued Operations | AMECO
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net	29,117	42,797
Contract assets	0	2,188
Other current assets	21,625	73,618
Current assets held for sale	50,742	118,603
PP&E, net	4,017	67,380
Goodwill	0	0
Investments	0	0
Other assets	15,315	13,810
Noncurrent assets held for sale	19,332	81,190
Total assets held for sale	70,074	199,793
Accounts payable	6,684	17,388
Short-term borrowings	0	0
Contract liabilities	10	782
Accrued salaries, wages and benefits	1,099	7,152
Other accrued liabilities	47,528	11,977
Current liabilities held for sale	55,321	37,299
Noncurrent liabilities held for sale	6,768	9,478
Total liabilities held for sale	62,089	46,777
Discontinued Operations | Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net	10,476	10,475
Contract assets	0	0
Other current assets	0	0
Current assets held for sale	10,476	10,475
PP&E, net	0	0
Goodwill	0	0
Investments	0	0
Other assets	0	0
Noncurrent assets held for sale	0	0
Total assets held for sale	10,476	10,475
Accounts payable	268	13
Short-term borrowings	0	0
Contract liabilities	0	0
Accrued salaries, wages and benefits	0	0
Other accrued liabilities	0	0
Current liabilities held for sale	268	13
Noncurrent liabilities held for sale	0	0
Total liabilities held for sale	268	13
Continuing Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net	0	0
Contract assets	0	0
Other current assets	0	0
Current assets held for sale	0	0
PP&E, net	24,326	24,538
Goodwill	0	0
Investments	5,712	5,064
Other assets	0	0
Noncurrent assets held for sale	30,038	29,602
Total assets held for sale	30,038	29,602
Accounts payable	0	0
Short-term borrowings	0	0
Contract liabilities	0	0
Accrued salaries, wages and benefits	0	0
Other accrued liabilities	0	0
Current liabilities held for sale	0	0
Noncurrent liabilities held for sale	0	0
Total liabilities held for sale	0	0
Total
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net	235,697	298,377
Contract assets	159,579	110,340
Other current assets	66,263	119,002
Current assets held for sale	461,539	527,719
PP&E, net	123,029	189,176
Goodwill	118,710	141,889
Investments	9,234	9,713
Other assets	136,141	149,231
Noncurrent assets held for sale	387,114	490,009
Total assets held for sale	848,653	1,017,728
Accounts payable	104,603	133,981
Short-term borrowings	17,953	20,525
Contract liabilities	40,204	47,779
Accrued salaries, wages and benefits	61,672	64,778
Other accrued liabilities	222,748	125,942
Current liabilities held for sale	447,180	393,005
Noncurrent liabilities held for sale	89,729	108,418
Total liabilities held for sale	$ 536,909	$ 501,423