Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Schedule of Equity Method Investments [Line Items]
Total revenue	$ 574,694,000		$ 477,826,000
Expenses
Depreciation and amortization	154,270,000		119,453,000
Total expenses	397,797,000		349,824,000
Operating income	176,897,000		128,002,000
Other expense
Interest expense	(113,554,000)		(100,433,000)
Income from continuing operations	67,756,000		38,496,000
Net income	67,756,000		57,931,000
Income from unconsolidated joint ventures	2,816,000		8,721,000
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Total revenue	38,034,000	[1]	135,650,000	[1]
Expenses
Operating	15,464,000		42,366,000
Depreciation and amortization	9,092,000		39,277,000
Total expenses	24,556,000		81,643,000
Operating income	13,478,000		54,007,000
Other expense
Interest expense	8,012,000		56,234,000
Net income	5,466,000		(2,227,000)
Company's share of net income (loss)	2,625,000		(1,858,000)
Basis differential	191,000		444,000
Elimination of inter-entity interest on partner loan	0		10,135,000
Income from unconsolidated joint ventures	2,816,000		8,721,000
Straight-line rent adjustments	600,000		4,000,000
"Above" and "below" market rent adjustments, net	$ 100,000		$ 20,400,000

[1] Includes straight-line rent adjustments of $0.6 million and $4.0 million for the three months ended March 31, 2014 and 2013, respectively. Includes net below-market rent adjustments of $0.1 million and $20.4 million for the three months ended March 31, 2014 and 2013, respectively.