Business Segments (Reportable Segments) (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) project $ / shares	Dec. 31, 2021 USD ($) $ / shares	Dec. 31, 2020 USD ($) $ / shares
Business Segments
Revenue from external customers	$ 3,790,755	$ 4,641,830	$ 5,318,763
Income (loss) from construction operations	(204,764)	226,804	262,344
Capital expenditures	59,780	38,594	54,781
Depreciation and amortization	$ 64,364	118,229	107,034
Number of mass-transit projects | project	2
Favorable Adjustments Reflecting Improved Profitability on Mass-Transit Project
Business Segments
Favorable arbitration		16,300
Favorable arbitration, after tax		$ 13,500
Favorable arbitration, after tax, diluted (in dollars per share) | $ / shares		$ 0.26
Operating Segments
Business Segments
Revenue from external customers	$ 4,075,967	$ 5,138,702	5,814,687
Income (loss) from construction operations	(139,730)	284,974	316,196
Capital expenditures	54,697	37,902	53,839
Depreciation and amortization	54,934	107,716	95,936
Corporate, Non-Segment
Business Segments
Income (loss) from construction operations	(65,034)	(58,170)	(53,852)
Capital expenditures	5,083	692	942
Depreciation and amortization	9,430	10,513	11,098
Intersegment Eliminations
Business Segments
Revenue from external customers	(285,212)	(496,872)	(495,924)
Civil
Business Segments
Revenue from external customers	1,734,882	2,095,760	2,199,899
Civil | Unfavorable Legal Ruling Pertaining to Mass-Transit Project in California
Business Segments
Loss contingency	(38,800)
Loss contingency, after tax	$ (30,700)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.60)
Civil | Unfavorable Adjustment Due to Civil Segment Highway Project in the Northeast
Business Segments
Loss contingency	$ (26,200)
Loss contingency, after tax	$ (18,900)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.37)
Civil | Adverse Legal Ruling Pertaining to Bridge Project in New York
Business Segments
Loss contingency	$ (25,500)
Loss contingency, after tax	$ (18,400)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.36)
Civil | Unfavorable Adjustments Due to Civil Segment Mass-transit Project in California
Business Segments
Loss contingency	$ (24,700)
Loss contingency, after tax	$ (17,900)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.35)
Civil | Unfavorable Settlement due to Project in Maryland
Business Segments
Loss contingency	$ (16,200)
Loss contingency, after tax	$ (11,700)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.23)
Civil | Unfavorable Non-cash Adjustment on Mass-transit Project in the Northeast
Business Segments
Loss contingency	$ (10,000)
Loss contingency, after tax	$ (7,200)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.14)
Civil | Favorable Operations Impacted in the Bridge Project Midwest
Business Segments
Loss contingency	$ (12,700)
Loss contingency, after tax	$ (9,100)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.18)
Civil | Unfavorable Adjustment Due to Changes in Estimates on Transportation Project in the Northeast
Business Segments
Favorable arbitration		(26,600)
Favorable arbitration, after tax		(20,500)
Civil | Favorable Adjustments Reflecting Improved Profitability on Mass-Transit Project
Business Segments
Favorable arbitration		29,000
Favorable arbitration, after tax		$ 20,900
Favorable arbitration, after tax, diluted (in dollars per share) | $ / shares		$ 0.41
Civil | Operating Segments
Business Segments
Revenue from external customers	$ 1,956,968	$ 2,443,828	2,565,210
Income (loss) from construction operations	21,123	266,214	245,835
Capital expenditures	49,819	37,067	51,044
Depreciation and amortization	51,123	102,723	90,250
Civil | Intersegment Eliminations
Business Segments
Revenue from external customers	(222,086)	(348,068)	(365,311)
Building
Business Segments
Revenue from external customers	1,242,571	1,428,102	1,984,641
Building | Unfavorable Adjustment Adverse Legal Ruling on Hospitality Project in Florida
Business Segments
Loss contingency	(11,300)
Loss contingency, after tax	$ (8,100)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.16)
Building | Operating Segments
Business Segments
Revenue from external customers	$ 1,305,468	1,574,759	2,114,459
Income (loss) from construction operations	7,166	28,721	53,158
Capital expenditures	2,333	359	878
Depreciation and amortization	1,713	1,677	1,703
Building | Intersegment Eliminations
Business Segments
Revenue from external customers	(62,897)	(146,657)	(129,818)
Specialty Contractors
Business Segments
Revenue from external customers	813,302	1,117,968	1,134,223
Specialty Contractors | Unfavorable Adjustment Due to Electrical Project in the Northeast
Business Segments
Loss contingency	(46,200)
Loss contingency, after tax	$ (33,500)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.65)
Specialty Contractors | Unfavorable Non-cash Adjustment Due to Appellate Court Decision Involving a Completed Mass-transit Project in New York
Business Segments
Loss contingency	$ (43,200)
Loss contingency, after tax	$ (31,400)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.61)
Specialty Contractors | Legal Appeal Due to Electrical Project in the New York
Business Segments
Loss contingency	$ (17,800)
Loss contingency, after tax	$ (12,900)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.25)
Specialty Contractors | Unfavorable Non-cash Adjustments on Mechanical Project in the Northeast
Business Segments
Loss contingency	$ (11,300)
Loss contingency, after tax	$ (8,200)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.16)
Specialty Contractors | Unfavorable Non-cash Adjustments on Another Mechanical Project, Northeast
Business Segments
Loss contingency	$ (11,100)
Loss contingency, after tax	$ (8,000)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.16)
Specialty Contractors | Favorable Legal Ruling Pertaining to Electrical Project in New York
Business Segments
Favorable arbitration		20,100
Favorable arbitration, after tax		$ 14,500
Favorable arbitration, after tax, diluted (in dollars per share) | $ / shares		$ 0.28
Specialty Contractors | Unfavorable Adjustment Due to Transportation Project
Business Segments
Loss contingency		$ 19,000
Loss contingency, after tax		$ 13,700
Loss contingency, after tax, diluted (in dollars per share) | $ / shares		$ (0.27)
Specialty Contractors | Unfavorable Adjustments Due to Second Transportation Project
Business Segments
Loss contingency		$ 17,600
Loss contingency, after tax		$ 12,700
Loss contingency, after tax, diluted (in dollars per share) | $ / shares		$ (0.25)
Specialty Contractors | Unfavorable Adjustments Due to Electrical Project in New York
Business Segments
Loss contingency		$ 16,200
Loss contingency, after tax		$ 11,700
Loss contingency, after tax, diluted (in dollars per share) | $ / shares		$ (0.23)
Specialty Contractors | Unfavorable Legal Ruling Pertaining to Mechanical Project in California
Business Segments
Loss contingency			(15,200)
Loss contingency, after tax			$ (11,000)
Loss contingency, after tax, diluted (in dollars per share) | $ / shares			$ 0.22
Specialty Contractors | Adverse Arbitration Ruling Pertaining to Electrical Project in New York
Business Segments
Loss contingency			$ (13,200)
Loss contingency, after tax			$ (9,600)
Loss contingency, after tax, diluted (in dollars per share) | $ / shares			$ 0.19
Specialty Contractors | Favorable Arbitration Decision
Business Segments
Favorable arbitration			$ 25,700
Favorable arbitration, after tax			$ 18,600
Favorable arbitration, after tax, diluted (in dollars per share) | $ / shares			$ 0.36
Specialty Contractors | Operating Segments
Business Segments
Revenue from external customers	$ 813,531	$ 1,120,115	$ 1,135,018
Income (loss) from construction operations	(168,019)	(9,961)	17,203
Capital expenditures	2,545	476	1,917
Depreciation and amortization	2,098	3,316	3,983
Specialty Contractors | Intersegment Eliminations
Business Segments
Revenue from external customers	(229)	$ (2,147)	$ (795)
Civil and Building | Unfavorable Adjustment Due to Changes in Estimates on Transportation Project in the Northeast
Business Segments
Loss contingency	(31,400)
Loss contingency, after tax	$ (24,400)
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share) | $ / shares	$ (0.48)
Favorable arbitration, after tax, diluted (in dollars per share) | $ / shares		$ (0.40)