Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Revenue	$ 1,127,470	$ 1,021,751	$ 2,176,457	$ 1,798,051
State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	676,863	635,139	1,284,330	1,070,849
Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	165,736	140,387	325,681	279,999
Private owners
Disaggregation of Revenue [Line Items]
Revenue	284,871	246,225	566,446	447,203
Civil
Disaggregation of Revenue [Line Items]
Revenue	546,488	554,123	1,018,653	903,993
Civil | State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	345,619	403,013	629,614	616,440
Civil | Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	119,312	98,711	232,766	194,695
Civil | Private owners
Disaggregation of Revenue [Line Items]
Revenue	81,557	52,399	156,273	92,858
Civil | Mass transit (includes certain transportation and tunneling projects)
Disaggregation of Revenue [Line Items]
Revenue	289,587	361,082	542,103	549,542
Civil | Military facilities
Disaggregation of Revenue [Line Items]
Revenue	117,779	83,811	222,923	169,378
Civil | Bridges
Disaggregation of Revenue [Line Items]
Revenue	62,308	51,326	89,980	81,971
Civil | Commercial and industrial sites
Disaggregation of Revenue [Line Items]
Revenue	36,630	29,192	76,120	51,918
Civil | Power and energy
Disaggregation of Revenue [Line Items]
Revenue	35,728	15,159	61,926	25,335
Civil | Other
Disaggregation of Revenue [Line Items]
Revenue	4,456	13,553	25,601	25,849
Building
Disaggregation of Revenue [Line Items]
Revenue	417,866	331,342	829,808	560,995
Building | State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	248,117	177,247	494,636	313,848
Building | Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	46,085	47,090	92,137	88,825
Building | Private owners
Disaggregation of Revenue [Line Items]
Revenue	123,664	107,005	243,035	158,322
Building | Mass transit (includes certain transportation and tunneling projects)
Disaggregation of Revenue [Line Items]
Revenue	57,323	62,871	118,498	96,191
Building | Other
Disaggregation of Revenue [Line Items]
Revenue	7,951	14,029	18,201	(49,095)
Building | Healthcare facilities
Disaggregation of Revenue [Line Items]
Revenue	135,954	55,839	247,941	106,256
Building | Government
Disaggregation of Revenue [Line Items]
Revenue	114,118	97,814	244,729	187,434
Building | Education facilities
Disaggregation of Revenue [Line Items]
Revenue	84,190	54,420	152,349	102,497
Building | Sports and entertainment
Disaggregation of Revenue [Line Items]
Revenue	10,621	13,364	26,260	26,830
Building | Commercial and industrial facilities
Disaggregation of Revenue [Line Items]
Revenue	4,073	16,026	15,442	54,297
Building | Hospitality and gaming
Disaggregation of Revenue [Line Items]
Revenue	3,636	16,979	6,388	36,585
Specialty Contractors
Disaggregation of Revenue [Line Items]
Revenue	163,116	136,286	327,996	333,063
Specialty Contractors | State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	83,127	54,879	160,080	140,561
Specialty Contractors | Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	339	(5,414)	778	(3,521)
Specialty Contractors | Private owners
Disaggregation of Revenue [Line Items]
Revenue	79,650	86,821	167,138	196,023
Specialty Contractors | Mass transit (includes certain transportation and tunneling projects)
Disaggregation of Revenue [Line Items]
Revenue	48,826	4,973	96,952	52,518
Specialty Contractors | Other
Disaggregation of Revenue [Line Items]
Revenue	15,868	(6,435)	25,807	(3,160)
Specialty Contractors | Healthcare facilities
Disaggregation of Revenue [Line Items]
Revenue	14,718	14,048	31,428	23,579
Specialty Contractors | Government
Disaggregation of Revenue [Line Items]
Revenue	18,491	20,763	41,444	41,832
Specialty Contractors | Commercial and industrial facilities
Disaggregation of Revenue [Line Items]
Revenue	30,213	53,583	58,423	107,810
Specialty Contractors | Multi-unit residential
Disaggregation of Revenue [Line Items]
Revenue	20,298	29,207	45,024	62,003
Specialty Contractors | Water
Disaggregation of Revenue [Line Items]
Revenue	$ 14,702	$ 20,147	$ 28,918	$ 48,481