Business Segments (Reconciliation of Segment Results to Consolidated Income Before Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Segments [Abstract]
Income (loss) from construction operations	$ 54,815	$ 34,045	$ 53,890	$ 71,062
Other income, net	1,050	40,990	1,830	41,406
Interest expense	(15,998)	(22,519)	(31,063)	(38,083)
INCOME BEFORE INCOME TAXES	$ 39,867	$ 52,516	$ 24,657	$ 74,385