Revenue (Schedule Of Revenue By Contract Type) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Contracts Revenue	$ 1,123,137	$ 1,199,505	$ 3,271,378	$ 3,564,140
Fixed Price [Member]
Contracts Revenue	558,575		1,659,982
Guaranteed Maximum Price [Member]
Contracts Revenue	290,814		864,499
Unit Price [Member]
Contracts Revenue	159,794		383,473
Cost Plus Fee And Other [Member]
Contracts Revenue	113,954		363,424
Civil [Member]
Contracts Revenue	431,488	395,820	1,097,075	1,172,977
Civil [Member] | Fixed Price [Member]
Contracts Revenue	272,996		716,826
Civil [Member] | Guaranteed Maximum Price [Member]
Contracts Revenue	3,025		11,200
Civil [Member] | Unit Price [Member]
Contracts Revenue	141,917		332,118
Civil [Member] | Cost Plus Fee And Other [Member]
Contracts Revenue	13,550		36,931
Building [Member]
Contracts Revenue	455,492	493,548	1,392,712	1,483,473
Building [Member] | Fixed Price [Member]
Contracts Revenue	91,972		267,630
Building [Member] | Guaranteed Maximum Price [Member]
Contracts Revenue	269,069		801,537
Building [Member] | Unit Price [Member]
Contracts Revenue	9,938		29,526
Building [Member] | Cost Plus Fee And Other [Member]
Contracts Revenue	84,513		294,019
Specialty Contractors [Member]
Contracts Revenue	236,157	$ 310,137	781,591	$ 907,690
Specialty Contractors [Member] | Fixed Price [Member]
Contracts Revenue	193,607		675,526
Specialty Contractors [Member] | Guaranteed Maximum Price [Member]
Contracts Revenue	18,720		51,762
Specialty Contractors [Member] | Unit Price [Member]
Contracts Revenue	7,939		21,829
Specialty Contractors [Member] | Cost Plus Fee And Other [Member]
Contracts Revenue	$ 15,891		$ 32,474