Revenue (Disaggregation Of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 861,027	$ 1,219,243	$ 1,813,181	$ 2,426,838
State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	500,701	697,688	1,030,464	1,307,695
Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	108,579	104,326	216,705	227,557
Private owners
Disaggregation of Revenue [Line Items]
Revenue	251,747	417,229	566,012	891,586
Civil
Disaggregation of Revenue [Line Items]
Revenue	403,622	555,352	794,417	1,030,927
Civil | State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	319,411	481,333	633,253	871,835
Civil | Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	62,991	49,335	113,685	100,968
Civil | Private owners
Disaggregation of Revenue [Line Items]
Revenue	21,220	24,684	47,479	58,124
Civil | Mass transit (includes certain transportation and tunneling projects)
Disaggregation of Revenue [Line Items]
Revenue	225,574	366,534	482,712	675,409
Civil | Bridges
Disaggregation of Revenue [Line Items]
Revenue	85,073	65,775	126,320	111,942
Civil | Military defense facilities
Disaggregation of Revenue [Line Items]
Revenue	60,355	44,585	110,149	94,121
Civil | Water
Disaggregation of Revenue [Line Items]
Revenue	22,384	24,800	43,036	51,610
Civil | Other
Disaggregation of Revenue [Line Items]
Revenue	10,236	53,658	32,200	97,845
Building
Disaggregation of Revenue [Line Items]
Revenue	266,941	382,660	597,589	789,893
Building | State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	89,473	92,275	213,163	168,856
Building | Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	42,402	49,287	88,500	99,648
Building | Private owners
Disaggregation of Revenue [Line Items]
Revenue	135,066	241,098	295,926	521,389
Building | Mass transit (includes certain transportation and tunneling projects)
Disaggregation of Revenue [Line Items]
Revenue	10,447	34,344	70,648	60,879
Building | Other
Disaggregation of Revenue [Line Items]
Revenue	17,829	25,995	30,897	55,439
Building | Municipal and government
Disaggregation of Revenue [Line Items]
Revenue	83,826	74,475	159,781	146,384
Building | Hospitality and gaming
Disaggregation of Revenue [Line Items]
Revenue	24,077	86,145	100,995	186,712
Building | Commercial and industrial facilities
Disaggregation of Revenue [Line Items]
Revenue	49,309	101,960	88,395	232,012
Building | Health care facilities
Disaggregation of Revenue [Line Items]
Revenue	50,277	13,598	85,837	24,007
Building | Education facilities
Disaggregation of Revenue [Line Items]
Revenue	31,176	46,143	61,036	84,460
Specialty Contractors
Disaggregation of Revenue [Line Items]
Revenue	190,464	281,231	421,175	606,018
Specialty Contractors | State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	91,817	124,080	184,048	267,004
Specialty Contractors | Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	3,186	5,704	14,520	26,941
Specialty Contractors | Private owners
Disaggregation of Revenue [Line Items]
Revenue	95,461	151,447	222,607	312,073
Specialty Contractors | Mass transit (includes certain transportation and tunneling projects)
Disaggregation of Revenue [Line Items]
Revenue	75,395	148,045	194,422	329,208
Specialty Contractors | Water
Disaggregation of Revenue [Line Items]
Revenue	13,972	17,514	35,419	38,668
Specialty Contractors | Other
Disaggregation of Revenue [Line Items]
Revenue	14,139	29,506	30,556	53,029
Specialty Contractors | Commercial and industrial facilities
Disaggregation of Revenue [Line Items]
Revenue	36,444	36,637	66,301	75,386
Specialty Contractors | Education facilities
Disaggregation of Revenue [Line Items]
Revenue	8,165	18,425	20,441	31,781
Specialty Contractors | Multi-unit residential
Disaggregation of Revenue [Line Items]
Revenue	28,243	30,649	53,181	73,444
Specialty Contractors | Federal government
Disaggregation of Revenue [Line Items]
Revenue	$ 14,106	$ 455	$ 20,855	$ 4,502