Revenue (Schedule Of Revenue By Contract Type) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 1,442,091	$ 1,189,345	$ 3,969,247	$ 3,273,107
Fixed price
Disaggregation of Revenue [Line Items]
Revenue	887,035	729,433	2,494,948	1,915,943
Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	310,401	164,261	799,428	571,242
Unit price
Disaggregation of Revenue [Line Items]
Revenue	155,951	170,368	379,855	418,745
Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	88,704	125,283	295,016	367,177
Civil
Disaggregation of Revenue [Line Items]
Revenue	611,996	524,546	1,667,601	1,331,698
Civil | Fixed price
Disaggregation of Revenue [Line Items]
Revenue	484,851	376,230	1,349,750	969,041
Civil | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	179	639	768	4,517
Civil | Unit price
Disaggregation of Revenue [Line Items]
Revenue	124,506	142,253	307,654	343,416
Civil | Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	2,460	5,424	9,429	14,724
Building
Disaggregation of Revenue [Line Items]
Revenue	508,140	415,346	1,462,925	1,277,130
Building | Fixed price
Disaggregation of Revenue [Line Items]
Revenue	117,650	144,514	401,957	395,123
Building | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	308,299	159,217	794,810	551,399
Building | Unit price
Disaggregation of Revenue [Line Items]
Revenue	254	2,922	1,417	10,950
Building | Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	81,937	108,693	264,741	319,658
Specialty Contractors
Disaggregation of Revenue [Line Items]
Revenue	321,955	249,453	838,721	664,279
Specialty Contractors | Fixed price
Disaggregation of Revenue [Line Items]
Revenue	284,534	208,689	743,241	551,779
Specialty Contractors | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	1,923	4,405	3,850	15,326
Specialty Contractors | Unit price
Disaggregation of Revenue [Line Items]
Revenue	31,191	25,193	70,784	64,379
Specialty Contractors | Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	$ 4,307	$ 11,166	$ 20,846	$ 32,795