Costs And Estimated Earnings In Excess Of Billings (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Costs and estimated earnings in excess of billings [Abstract]
Claims	$ 486,067	$ 477,425
Unapproved change orders	263,130	207,475
Other unbilled costs and profits	101,437	146,926
Total costs and estimated earnings in excess of billings	$ 850,634	$ 831,826