Business Segments (Reportable Segments) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Revenue	$ 1,048,987	$ 776,300
Income (loss) from construction operations	48,806	(81,945)
Capital expenditures	10,434	17,796
Depreciation and amortization	13,582	10,408
Adverse Legal Ruling Pertaining To Transit Project In New York
Segment Reporting Information [Line Items]
Loss contingency		83,600
Loss contingency, after tax		$ 60,100
Loss contingency, after tax, diluted (in dollars per share)		$ 1.17
Operating Segments
Segment Reporting Information [Line Items]
Revenue	1,089,878	$ 804,263
Income (loss) from construction operations	68,551	(64,645)
Capital expenditures	8,651	17,526
Depreciation and amortization	11,437	8,057
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	(40,891)	(27,963)
Corporate
Segment Reporting Information [Line Items]
Revenue	0	0
Income (loss) from construction operations	(19,745)	(17,300)
Capital expenditures	1,783	270
Depreciation and amortization	2,145	2,351
Civil
Segment Reporting Information [Line Items]
Revenue	472,165	349,870
Civil | Favorable Adjustment Legal Ruling Pertaining To Mass-Transit Project In California
Segment Reporting Information [Line Items]
Favorable arbitration	10,200
Favorable arbitration, after tax	$ 7,500
Favorable arbitration, after tax, diluted (in dollars per share)	$ 0.14
Civil | Unfavorable Legal Ruling Pertaining to Mass-Transit Project in California
Segment Reporting Information [Line Items]
Loss contingency		28,000
Loss contingency, after tax		$ 22,200
Loss contingency, after tax, diluted (in dollars per share)		$ 0.43
Civil | Operating Segments
Segment Reporting Information [Line Items]
Revenue	$ 502,822	$ 378,224
Income (loss) from construction operations	70,743	18,012
Capital expenditures	8,131	15,065
Depreciation and amortization	10,254	6,981
Civil | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	(30,657)	(28,354)
Building
Segment Reporting Information [Line Items]
Revenue	411,942	229,653
Building | Adverse Legal Ruling Pertaining To Transit Project In New York
Segment Reporting Information [Line Items]
Loss contingency		72,200
Building | Operating Segments
Segment Reporting Information [Line Items]
Revenue	422,176	229,291
Income (loss) from construction operations	16,120	(70,209)
Capital expenditures	217	2,017
Depreciation and amortization	585	457
Building | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	(10,234)	362
Specialty Contractors
Segment Reporting Information [Line Items]
Revenue	164,880	196,777
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 | Adverse Legal Ruling Pertaining To Transit Project In New York
Segment Reporting Information [Line Items]
Loss contingency		11,400
Specialty Contractors | Operating Segments
Segment Reporting Information [Line Items]
Revenue	$ 164,880	196,748
Income (loss) from construction operations	(18,312)	(12,448)
Capital expenditures	303	444
Depreciation and amortization	598	619
Specialty Contractors | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	$ 0	$ 29