Contract Assets and Liabilities (Schedule Of Contract Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Abstract]
Retainage receivable	$ 621,414	$ 562,375
Billings in Excess of Cost [Abstract]
Claims	743,057	705,993
Unapproved change orders	372,830	362,264
Other unbilled costs and profits	64,328	55,287
Total costs and estimated earnings in excess of billings	1,180,215	1,123,544
Capitalized contract costs	84,391	80,294
Total contract assets	$ 1,886,020	$ 1,766,213