Segment Reporting (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Reconciliation of NOI to net income
Net income		$ 237,877	$ 208,053
Indirect operating expenses, net of corporate income		16,537	15,399
Investments and investment management expense		1,145	1,034
Business Combination, Acquisition Related Costs		3,462	1,187
Interest expense, net	[1]	43,410	45,573
General and administrative expense		11,404	10,468
Equity in (income) loss of unconsolidated real estate entities		(27,969)	(34,566)
Depreciation expense	[1]	127,216	116,853
Income Tax Expense (Benefit)		37	15
Casualty and Impairment Loss (Gain)		(2,202)	5,788
Gain on sale of real estate assets in continuing operations		51,430	70,958
Net operating income from real estate assets sold or held for sale (1)		(721)	(3,219)
Net operating income		$ 358,766	$ 295,627

[1] Represents NOI from real estate assets sold or held for sale that are not otherwise classified as discontinued operations.