Revenue (Schedule Of Revenue By Contract Type) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
REVENUE	$ 1,349,516	$ 1,442,091	$ 1,276,427	$ 1,250,729	$ 1,177,725	$ 1,189,345	$ 1,125,275	$ 958,487	$ 5,318,763	$ 4,450,832	$ 4,454,662
Fixed price
Disaggregation of Revenue [Line Items]
REVENUE									3,312,393	2,646,436	2,289,753
Guaranteed maximum price
Disaggregation of Revenue [Line Items]
REVENUE									1,154,028	780,352	1,117,934
Unit price
Disaggregation of Revenue [Line Items]
REVENUE									476,672	539,881	534,335
Cost plus fee and other
Disaggregation of Revenue [Line Items]
REVENUE									375,670	484,163	512,640
Civil
Disaggregation of Revenue [Line Items]
REVENUE									2,199,899	1,779,352	1,586,093
Civil | Fixed price
Disaggregation of Revenue [Line Items]
REVENUE									1,792,765	1,315,195	1,054,473
Civil | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
REVENUE									1,829	6,951	15,709
Civil | Unit price
Disaggregation of Revenue [Line Items]
REVENUE									392,548	436,015	469,305
Civil | Cost plus fee and other
Disaggregation of Revenue [Line Items]
REVENUE									12,757	21,191	46,606
Building
Disaggregation of Revenue [Line Items]
REVENUE									1,984,641	1,742,040	1,861,699
Building | Fixed price
Disaggregation of Revenue [Line Items]
REVENUE									508,655	561,831	377,538
Building | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
REVENUE									1,136,782	752,110	1,040,093
Building | Unit price
Disaggregation of Revenue [Line Items]
REVENUE									867	12,063	32,468
Building | Cost plus fee and other
Disaggregation of Revenue [Line Items]
REVENUE									338,337	416,036	411,600
Specialty Contractors
Disaggregation of Revenue [Line Items]
REVENUE									1,134,223	929,440	1,006,870
Specialty Contractors | Fixed price
Disaggregation of Revenue [Line Items]
REVENUE									1,010,973	769,410	857,742
Specialty Contractors | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
REVENUE									15,417	21,291	62,132
Specialty Contractors | Unit price
Disaggregation of Revenue [Line Items]
REVENUE									83,257	91,803	32,562
Specialty Contractors | Cost plus fee and other
Disaggregation of Revenue [Line Items]
REVENUE									$ 24,576	$ 46,936	$ 54,434