Contract Assets and Liabilities (Schedule Of Contract Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Abstract]
Retainage receivable	$ 661,382	$ 648,441
Costs and estimated earnings in excess of billings:
Claims	806,534	752,783
Unapproved change orders	369,411	415,489
Other unbilled costs and profits	80,047	68,462
Total costs and estimated earnings in excess of billings	1,255,992	1,236,734
Capitalized contract costs	73,898	74,452
Total contract assets	$ 1,991,272	$ 1,959,627