Discontinued Operations - Assets and Liabilities Held for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contract assets	$ 996,716	$ 1,130,918
Short-term borrowings	45,240	26,887
Other accrued liabilities	419,352	367,689
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts and notes receivable, net	191,924	298,489
Contract assets	353,667	414,062
Other current assets	83,164	73,094
Current assets held for sale	628,755	785,645
Property, plant and equipment, net	243,868	267,791
Goodwill	70,366	70,366
Investments	32,767	35,354
Other assets	21,508	3,088
Noncurrent assets held for sale(1)	368,509	376,599
Total assets held for sale	997,264	1,162,244
Trade accounts payable	214,394	240,225
Short-term borrowings	767	0
Contract liabilities	66,529	55,409
Accrued salaries, wages and benefits	81,221	71,569
Other accrued liabilities	19,289	13,612
Current liabilities held for sale	382,200	380,815
Noncurrent liabilities held for sale(1)	28,947	17,498
Total liabilities held for sale	411,147	398,313
Discontinued Operations | Government
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts and notes receivable, net	109,536	202,837
Contract assets	349,610	411,777
Other current assets	23,675	15,076
Current assets held for sale	482,821	629,690
Property, plant and equipment, net	10,080	10,714
Goodwill	58,029	58,029
Investments	32,767	35,354
Other assets	15,096	2,021
Noncurrent assets held for sale(1)	115,972	106,118
Total assets held for sale	598,793	735,808
Trade accounts payable	180,597	219,617
Short-term borrowings	767	0
Contract liabilities	64,196	51,129
Accrued salaries, wages and benefits	71,873	64,387
Other accrued liabilities	11,716	10,473
Current liabilities held for sale	329,149	345,606
Noncurrent liabilities held for sale(1)	24,462	16,113
Total liabilities held for sale	353,611	361,719
Discontinued Operations | AMECO
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts and notes receivable, net	82,388	95,652
Contract assets	4,057	2,285
Other current assets	59,489	58,018
Current assets held for sale	145,934	155,955
Property, plant and equipment, net	233,788	257,077
Goodwill	12,337	12,337
Investments	0	0
Other assets	6,412	1,067
Noncurrent assets held for sale(1)	252,537	270,481
Total assets held for sale	398,471	426,436
Trade accounts payable	33,797	20,608
Short-term borrowings	0	0
Contract liabilities	2,333	4,280
Accrued salaries, wages and benefits	9,348	7,182
Other accrued liabilities	7,573	3,139
Current liabilities held for sale	53,051	35,209
Noncurrent liabilities held for sale(1)	4,485	1,385
Total liabilities held for sale	57,536	$ 36,594
Continuing Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts and notes receivable, net	2,543
Contract assets	2,936
Other current assets	305
Current assets held for sale	5,784
Property, plant and equipment, net	70,937
Goodwill	1,499
Investments	6,309
Other assets	0
Noncurrent assets held for sale(1)	78,745
Total assets held for sale	84,529
Trade accounts payable	550
Short-term borrowings	0
Contract liabilities	0
Accrued salaries, wages and benefits	0
Other accrued liabilities	2,646
Current liabilities held for sale	3,196
Noncurrent liabilities held for sale(1)	0
Total liabilities held for sale	3,196
Total
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts and notes receivable, net	194,467
Contract assets	356,603
Other current assets	83,469
Current assets held for sale	634,539
Property, plant and equipment, net	314,805
Goodwill	71,865
Investments	39,076
Other assets	21,508
Noncurrent assets held for sale(1)	447,254
Total assets held for sale	1,081,793
Trade accounts payable	214,944
Short-term borrowings	767
Contract liabilities	66,529
Accrued salaries, wages and benefits	81,221
Other accrued liabilities	21,935
Current liabilities held for sale	385,396
Noncurrent liabilities held for sale(1)	28,947
Total liabilities held for sale	$ 414,343