Corporate Indebtedness (Schedule of Consolidated Interest Expense, Excluding Capitalized Interest)(Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Interest expense
Interest expense before capitalized interest	$ 71,992	$ 95,568	$ 144,414	$ 197,722
Interest capitalized	(6,743)	(5,433)	(13,022)	(12,051)
Interest income	(393)	(1,046)	(914)	(1,910)
Interest expense, net	$ 64,856	$ 89,089	$ 130,478	$ 183,761