Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting
Net income	$ 75,469	$ 57,609
Indirect operating expenses, net of corporate income	9,041	8,036
Investments and investment management expense	1,015	1,446
Expensed acquisition, development and other pursuit costs	40,059	239
Interest expense, net	38,174	33,626
Loss on extinguishment of debt, net		1,179
General and administrative expense	10,039	9,710
Equity in (income) loss of unconsolidated entities	18,564	(2,175)
Depreciation expense	109,829	61,571
Gain on sale of real estate assets	(84,491)
Income from discontinued operations	(2,446)	(3,935)
Net operating income	$ 215,253	$ 167,306