Business Segments (Reportable Segments) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Revenue	$ 1,127,470	$ 1,021,751	$ 2,176,457	$ 1,798,051
Income (loss) from construction operations	40,493	2,388	89,299	(79,557)
Capital expenditures	10,918	12,827	21,352	30,623
Depreciation and amortization	14,006	10,346	27,588	20,754
Costs for share-based payment arrangements	16,900	2,600	22,400	5,600
Costs for share-based payment arrangements, after tax	$ (12,400)	$ (1,900)	$ (16,500)	$ (4,100)
Costs for share-based payment arrangements, after tax (in dollars per share)	$ (0.23)	$ (0.04)	$ (0.31)	$ (0.08)
Adverse Legal Ruling Pertaining to Mixed-Use Project in New York
Segment Reporting Information [Line Items]
Loss contingency			$ (83,600)	$ 83,600
Loss contingency, after tax				$ 60,100
Loss contingency, after tax, diluted (in dollars per share)				$ 1.16
Operating Segments
Segment Reporting Information [Line Items]
Revenue	$ 1,174,382	$ 1,013,809	2,264,260	$ 1,818,072
Income (loss) from construction operations	72,788	21,744	141,339	(42,901)
Capital expenditures	9,517	11,357	18,168	28,883
Depreciation and amortization	11,886	8,151	23,323	16,208
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	(46,912)	7,942	(87,803)	(20,021)
Corporate
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Income (loss) from construction operations	(32,295)	(19,356)	(52,040)	(36,656)
Capital expenditures	1,401	1,470	3,184	1,740
Depreciation and amortization	2,120	2,195	4,265	4,546
Civil
Segment Reporting Information [Line Items]
Revenue	546,488	554,123	1,018,653	903,993
Civil | Unfavorable Adjustment Due To Highway Project In Northeast
Segment Reporting Information [Line Items]
Loss contingency	12,400		12,400
Loss contingency, after tax	$ 9,100		$ 9,100
Loss contingency, after tax, diluted (in dollars per share)	$ 0.17		$ 0.17
Civil | Unfavorable Legal Ruling Pertaining to Mass-Transit Project in California
Segment Reporting Information [Line Items]
Gain contingency		58,100
Gain contingency, after tax		$ 46,100
Gain contingency, after tax, diluted (in dollars per share)		$ 0.89
Civil | Favorable Adjustment Legal Ruling Pertaining To Mass-Transit Project In California
Segment Reporting Information [Line Items]
Gain contingency			$ 10,200	30,100
Gain contingency, after tax			$ 7,500	$ 23,900
Gain contingency, after tax, diluted (in dollars per share)			$ 0.14	$ 0.46
Civil | Operating Segments
Segment Reporting Information [Line Items]
Revenue	$ 577,519	$ 555,553	$ 1,080,341	$ 933,777
Income (loss) from construction operations	75,587	105,407	146,330	123,419
Capital expenditures	9,479	9,643	17,610	24,708
Depreciation and amortization	10,727	7,074	20,981	14,055
Civil | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	(31,031)	(1,430)	(61,688)	(29,784)
Building
Segment Reporting Information [Line Items]
Revenue	417,866	331,342	829,808	560,995
Building | Adverse Legal Ruling Pertaining to Mixed-Use Project in New York
Segment Reporting Information [Line Items]
Loss contingency			(72,200)	72,200
Building | Operating Segments
Segment Reporting Information [Line Items]
Revenue	433,797	321,933	855,973	551,224
Income (loss) from construction operations	5,047	(13,831)	21,167	(84,040)
Capital expenditures	68	1,458	285	3,475
Depreciation and amortization	585	455	1,170	912
Building | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	(15,931)	9,409	(26,165)	9,771
Specialty Contractors
Segment Reporting Information [Line Items]
Revenue	163,116	136,286	327,996	333,063
Specialty Contractors | Unfavorable Arbitration Ruling Pertaining to Electrical Project in New York
Segment Reporting Information [Line Items]
Loss contingency			12,000
Loss contingency, after tax			$ 8,800
Loss contingency, after tax, diluted (in dollars per share)			$ 0.17
Specialty Contractors | Unfavorable Adjustment due to Changes in Estimates on Transportation Project in the Northeast
Segment Reporting Information [Line Items]
Loss contingency		35,800		35,800
Loss contingency, after tax		$ 26,000		$ 26,000
Loss contingency, after tax, diluted (in dollars per share)		$ 0.50		$ 0.50
Specialty Contractors | Adverse Legal Ruling Pertaining to Mixed-Use Project in New York
Segment Reporting Information [Line Items]
Loss contingency			$ (11,400)	$ 11,400
Specialty Contractors | Unfavorable Adjustment due to Educational Facilities Project in New York
Segment Reporting Information [Line Items]
Loss contingency		$ 24,700		24,700
Loss contingency, after tax		$ 18,000		$ 18,000
Loss contingency, after tax, diluted (in dollars per share)		$ 0.35		$ 0.35
Specialty Contractors | Operating Segments
Segment Reporting Information [Line Items]
Revenue	163,066	$ 136,323	327,946	$ 333,071
Income (loss) from construction operations	(7,846)	(69,832)	(26,158)	(82,280)
Capital expenditures	(30)	256	273	700
Depreciation and amortization	574	622	1,172	1,241
Specialty Contractors | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	$ 50	(37)	$ 50	(8)
Civil and Building | Unfavorable Adjustment due to Changes in Estimates on Transportation Project in the Northeast
Segment Reporting Information [Line Items]
Loss contingency		13,100		13,100
Loss contingency, after tax		$ 10,200		$ 10,200
Loss contingency, after tax, diluted (in dollars per share)		$ 0.20		$ 0.20