Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Percentage of physical occupancy	95.00%
Anniversary of Completion of Development or Redevelopment (in years)	1 year
Reconciliation of NOI to net income
Net income	$ 697,327	$ 352,771	$ 423,562
Indirect operating expenses, net of corporate income	49,055	41,554	31,911
Investments and investment management expense	4,485	3,990	6,071
Expensed acquisition, development and other pursuit costs, net of recoveries	(3,717)	45,050	11,350
Interest expense, net	180,618	172,402	136,920
Loss on extinguishment of debt, net	412	14,921	1,179
Loss on interest rate contract	0	51,000	0
General and administrative expense	41,425	39,573	34,101
Equity in loss (income) of unconsolidated entities	(148,766)	11,154	(20,914)
Depreciation expense	442,682	560,215	243,680
Income tax expense	9,368	0	0
Casualty and impairment loss	0	0	1,449
Gain on acquisition of unconsolidated real estate entity	0	0	(14,194)
Gain on sale of real estate assets	(85,415)	(240)	(280)
Gain on sale of discontinued operations	(37,869)	(278,231)	(146,311)
Income from discontinued operations	(310)	(16,713)	(26,820)
Net operating income from real estate assets sold or held for sale, not classified as discontinued operations	(15,199)	(19,448)	(13,776)
Net operating income	$ 1,134,096	$ 977,998	$ 667,928