Corporate Indebtedness (Schedule of Consolidated Interest Expense, Excluding Capitalized Interest)(Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest expense
Interest expense before capitalized interest	$ 348,062	$ 357,926	$ 342,648
Interest capitalized	(24,067)	(31,108)	(22,750)
Interest income	(2,796)	(2,948)	(2,498)
Interest expense, net	$ 321,199	$ 323,870	$ 317,400