Revenue (Schedule Of Revenue By Contract Type) (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
Fixed price
Disaggregation of Revenue [Line Items]
Revenue	559,746	802,707	1,198,320	1,599,780
Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	149,616	250,463	326,751	523,317
Unit price
Disaggregation of Revenue [Line Items]
Revenue	94,274	115,655	159,639	196,796
Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	57,391	50,418	128,471	106,945
Civil
Disaggregation of Revenue [Line Items]
Revenue	403,622	555,352	794,417	1,030,927
Civil | Fixed price
Disaggregation of Revenue [Line Items]
Revenue	337,414	461,068	674,407	880,224
Civil | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	301	498	594	1,768
Civil | Unit price
Disaggregation of Revenue [Line Items]
Revenue	72,210	88,516	122,720	141,249
Civil | Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	(6,303)	5,270	(3,304)	7,686
Building
Disaggregation of Revenue [Line Items]
Revenue	266,941	382,660	597,589	789,893
Building | Fixed price
Disaggregation of Revenue [Line Items]
Revenue	64,296	95,349	166,814	179,798
Building | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	145,954	247,402	317,463	517,856
Building | Unit price
Disaggregation of Revenue [Line Items]
Revenue	0	(1,564)	33	(1,453)
Building | Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	56,691	41,473	113,279	93,692
Specialty Contractors
Disaggregation of Revenue [Line Items]
Revenue	190,464	281,231	421,175	606,018
Specialty Contractors | Fixed price
Disaggregation of Revenue [Line Items]
Revenue	158,036	246,290	357,099	539,758
Specialty Contractors | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	3,361	2,563	8,694	3,693
Specialty Contractors | Unit price
Disaggregation of Revenue [Line Items]
Revenue	22,064	28,703	36,886	57,000
Specialty Contractors | Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	$ 7,003	$ 3,675	$ 18,496	$ 5,567