Business Segments (Reportable Segments) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Segments
Revenue from external customers	$ 3,880,227	$ 3,790,755	$ 4,641,830
Income (loss) from construction operations	(114,597)	(204,764)	226,804
Capital expenditures	52,953	59,780	38,594
Depreciation and amortization	45,229	64,364	118,229
Adverse Legal Ruling Pertaining To Mixed-Use Project In New York
Business Segments
Loss contingency	83,600
Loss contingency, after tax	$ 60,800
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share)	$ 1.17
Favorable Adjustments Reflecting Improved Profitability on Mass-Transit Project
Business Segments
Favorable arbitration, after tax			$ 13,500
Favorable arbitration, after tax, diluted (in dollars per share)			$ 0.26
Operating Segments
Business Segments
Revenue from external customers	$ 3,967,868	4,075,967	$ 5,138,702
Income (loss) from construction operations	(37,419)	(139,730)	284,974
Capital expenditures	46,500	54,697	37,902
Depreciation and amortization	36,357	54,934	107,716
Corporate, Non-Segment
Business Segments
Income (loss) from construction operations	(77,178)	(65,034)	(58,170)
Capital expenditures	6,453	5,083	692
Depreciation and amortization	8,872	9,430	10,513
Intersegment Eliminations
Business Segments
Revenue from external customers	(87,641)	(285,212)	(496,872)
Civil
Business Segments
Revenue from external customers	1,883,865	1,734,882	2,095,760
Loss contingency	40,700
Civil | Unfavorable Legal Ruling Pertaining to Mass-Transit Project in California
Business Segments
Loss contingency	23,200
Loss contingency, after tax	$ 17,000
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share)	$ 0.33
Civil | Favorable Adjustment Legal Ruling Pertaining To Mass-Transit Project In California
Business Segments
Favorable arbitration	$ 8,800
Favorable arbitration, after tax	$ 7,100
Favorable arbitration, after tax, diluted (in dollars per share)	$ 0.14
Civil | Unfavorable Adjustments Due to Highway Project in Virginia
Business Segments
Loss contingency	$ 12,800
Loss contingency, after tax	$ 9,400
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share)	$ 0.18
Civil | Favorable Adjustment Legal Ruling Pertaining To Mass-Transit Project In West Coast
Business Segments
Favorable arbitration	$ 19,000
Favorable arbitration, after tax	$ 15,200
Favorable arbitration, after tax, diluted (in dollars per share)	$ 0.29
Civil | Favorable Adjustments Due To Improved Performance
Business Segments
Favorable arbitration	$ 58,100
Civil | Unfavorable Legal Ruling Pertaining To Mass-Transit Project In West Coast
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)		$ 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)		$ 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)		$ 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)		$ 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)		$ 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)		$ 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)		$ 0.18
Civil | Favorable Adjustments From Construction Operations
Business Segments
Favorable arbitration			29,000
Favorable arbitration, after tax			$ 20,900
Favorable arbitration, after tax, diluted (in dollars per share)			$ 0.41
Civil | Favorable Adjustments Reflecting Improved Profitability on Mass-Transit Project
Business Segments
Favorable arbitration			$ 16,300
Civil | Unfavorable Adjustment Due to Transportation Project
Business Segments
Loss contingency			19,000
Loss contingency, after tax			13,700
Civil | Operating Segments
Business Segments
Revenue from external customers	1,971,194	$ 1,956,968	2,443,828
Income (loss) from construction operations	198,609	21,123	266,214
Capital expenditures	41,318	49,819	37,067
Depreciation and amortization	31,685	51,123	102,723
Civil | Intersegment Eliminations
Business Segments
Revenue from external customers	(87,329)	(222,086)	(348,068)
Building
Business Segments
Revenue from external customers	1,302,539	1,242,571	1,428,102
Building | Unfavorable Adjustment Adverse Legal Ruling on Hospitality Project in Florida
Business Segments
Loss contingency	14,600	11,300
Loss contingency, after tax	$ 10,700	$ 8,100
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share)	$ 0.21	$ 0.16
Building | Adverse Legal Ruling Pertaining To Mixed-Use Project In New York
Business Segments
Loss contingency	$ 72,200
Building | Operating Segments
Business Segments
Revenue from external customers	1,302,636	$ 1,305,468	1,574,759
Income (loss) from construction operations	(91,206)	7,166	28,721
Capital expenditures	3,932	2,333	359
Depreciation and amortization	2,227	1,713	1,677
Building | Intersegment Eliminations
Business Segments
Revenue from external customers	(97)	(62,897)	(146,657)
Specialty Contractors
Business Segments
Revenue from external customers	693,823	813,302	1,117,968
Specialty Contractors | Unfavorable Adjustment Due to Changes in Estimates on Transportation Project in the Northeast
Business Segments
Loss contingency	62,200
Loss contingency, after tax	$ 45,700
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share)	$ 0.88
Specialty Contractors | Unfavorable Adjustment Due To Educational Facilities Project In New York
Business Segments
Loss contingency	$ 24,700
Loss contingency, after tax	$ 18,100
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share)	$ 0.35
Specialty Contractors | Unfavorable Adjustment On Multi-Unit Residential Project In New York
Business Segments
Loss contingency	$ (16,900)
Loss contingency, after tax	$ 12,400
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share)	$ 0.24
Specialty Contractors | Unfavorable Adjustment Legal Ruling Pertaining To Mass-Transit Project In California
Business Segments
Loss contingency	$ 9,400
Loss contingency, after tax	$ 6,900
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share)	$ 0.13
Specialty Contractors | Adverse Legal Ruling Pertaining To Mixed-Use Project In New York
Business Segments
Loss contingency	$ 11,400
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)		$ 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)		$ 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)		$ 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)		$ 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)		$ 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)			$ 0.28
Specialty Contractors | Unfavorable Adjustment Due to Transportation Project
Business Segments
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share)			$ 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, loss in period, after tax, per share, diluted (in dollars per share)			$ 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, loss in period, after tax, per share, diluted (in dollars per share)			$ 0.23
Specialty Contractors | Operating Segments
Business Segments
Revenue from external customers	694,038	$ 813,531	$ 1,120,115
Income (loss) from construction operations	(144,822)	(168,019)	(9,961)
Capital expenditures	1,250	2,545	476
Depreciation and amortization	2,445	2,098	3,316
Specialty Contractors | Intersegment Eliminations
Business Segments
Revenue from external customers	(215)	(229)	(2,147)
Civil and Building | 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
Favorable arbitration, after tax, diluted (in dollars per share)			$ 0.40
Loss contingency	28,300	31,400
Loss contingency, after tax	$ 22,200	$ 24,400
Loss contingency, loss in period, after tax, per share, diluted (in dollars per share)	$ 0.43	$ 0.48