Contract Assets And Liabilities (Schedule Of Contract Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Abstract]
Retainage payable	$ 315,135	$ 252,181
Billings in excess of costs and estimated earnings	839,222	844,389
Total contract liabilities	$ 1,154,357	$ 1,096,570