Revenue (Disaggregation Of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Revenue	$ 776,300	$ 952,154
State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	435,710	529,763
Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	139,612	108,126
Private owners
Disaggregation of Revenue [Line Items]
Revenue	200,978	314,265
Civil
Disaggregation of Revenue [Line Items]
Revenue	349,870	390,795
Civil | State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	213,427	313,842
Civil | Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	95,984	50,694
Civil | Private owners
Disaggregation of Revenue [Line Items]
Revenue	40,459	26,259
Civil | Mass transit (includes certain transportation and tunneling projects)
Disaggregation of Revenue [Line Items]
Revenue	188,460	257,138
Civil | Military defense facilities
Disaggregation of Revenue [Line Items]
Revenue	85,567	49,794
Civil | Bridges
Disaggregation of Revenue [Line Items]
Revenue	30,645	41,247
Civil | Commercial and industrial sites
Disaggregation of Revenue [Line Items]
Revenue	22,504	11,910
Civil | Other
Disaggregation of Revenue [Line Items]
Revenue	22,694	30,706
Building
Disaggregation of Revenue [Line Items]
Revenue	229,653	330,648
Building | State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	136,601	123,690
Building | Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	41,735	46,098
Building | Private owners
Disaggregation of Revenue [Line Items]
Revenue	51,317	160,860
Building | Mass transit (includes certain transportation and tunneling projects)
Disaggregation of Revenue [Line Items]
Revenue	33,320	60,201
Building | Other
Disaggregation of Revenue [Line Items]
Revenue	(63,124)	8,296
Building | Municipal and government
Disaggregation of Revenue [Line Items]
Revenue	89,620	75,955
Building | Health care facilities
Disaggregation of Revenue [Line Items]
Revenue	50,417	35,560
Building | Education facilities
Disaggregation of Revenue [Line Items]
Revenue	48,077	29,860
Building | Commercial and industrial facilities
Disaggregation of Revenue [Line Items]
Revenue	38,271	39,086
Building | Hospitality and gaming
Disaggregation of Revenue [Line Items]
Revenue	19,606	76,918
Building | Sports and entertainment
Disaggregation of Revenue [Line Items]
Revenue	13,466	4,772
Specialty Contractors
Disaggregation of Revenue [Line Items]
Revenue	196,777	230,711
Specialty Contractors | State and local agencies
Disaggregation of Revenue [Line Items]
Revenue	85,682	92,231
Specialty Contractors | Federal agencies
Disaggregation of Revenue [Line Items]
Revenue	1,893	11,334
Specialty Contractors | Private owners
Disaggregation of Revenue [Line Items]
Revenue	109,202	127,146
Specialty Contractors | Mass transit (includes certain transportation and tunneling projects)
Disaggregation of Revenue [Line Items]
Revenue	47,545	119,027
Specialty Contractors | Other
Disaggregation of Revenue [Line Items]
Revenue	3,472	7,844
Specialty Contractors | Health care facilities
Disaggregation of Revenue [Line Items]
Revenue	9,531	8,574
Specialty Contractors | Education facilities
Disaggregation of Revenue [Line Items]
Revenue	8,253	12,276
Specialty Contractors | Commercial and industrial facilities
Disaggregation of Revenue [Line Items]
Revenue	54,227	29,857
Specialty Contractors | Multi-unit residential
Disaggregation of Revenue [Line Items]
Revenue	32,796	24,938
Specialty Contractors | Water
Disaggregation of Revenue [Line Items]
Revenue	28,334	21,447
Specialty Contractors | Federal government
Disaggregation of Revenue [Line Items]
Revenue	$ 12,619	$ 6,748