Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Reconciliation of NOI to net income
Net income	$ 141,599	$ 75,469
Indirect operating expenses, net of corporate income	10,818	9,041
Investments and investment management expense	979	1,015
Expensed acquisition, development and other pursuit costs	715	40,059
Interest expense, net	42,533	38,174
General and administrative expense	9,236	10,039
Equity in loss (income) of unconsolidated entities	(5,223)	18,564
Depreciation expense	106,367	105,559
Gain on sale of real estate assets	(37,869)	(84,491)
Income from discontinued operations	(310)	(5,746)
Net operating income	$ 268,845	$ 207,683