Contract Assets and Liabilities (Schedule of Contract Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Contract Assets and Liabilities [Abstract]
Retainage receivable	$ 542,274	$ 478,744
Claims	756,760	698,274
Unapproved change orders	334,125	354,000
Other unbilled costs and profits	68,448	90,021
Total costs and estimated earnings in excess of billings	1,159,333	1,142,295
Capitalized contract costs	60,290	37,404
Total contract assets	$ 1,761,897	$ 1,658,443