Contract Assets And Liabilities (Schedule Of Contract Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Contract Assets and Liabilities [Abstract]
Retainage receivable	$ 490,751	$ 535,939	$ 535,939
Claims	646,262	549,849
Unapproved change orders	334,777	296,591
Other unbilled costs and profits	63,194	86,318
Total costs and estimated earnings in excess of billings	1,044,233	932,758	$ 932,758
Capitalized contract costs	41,434	32,773
Total contract assets	$ 1,576,418	$ 1,501,470