Investment in Partially Owned Entities (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Liabilities and Equity
Carrying value of investments in unconsolidated entities	$ 248,865		$ 248,865		$ 263,918
Company’s share of:
Net income, net of excess basis depreciation of $129 and $125, and $385 and $400, respectively	(2,089)	3,000	334	11,044
Unconsolidated Entities [Member]
Assets
Real estate assets, net of accumulated depreciation	1,513,473		1,513,473		1,558,312
Other assets	261,235		261,235		272,810
Total Assets	1,774,708		1,774,708		1,831,122
Liabilities and Equity
Equity Method Investments Long Term Debt	1,075,711		1,075,711		1,135,630
Other liabilities	103,382		103,382		96,217
Equity	595,615		595,615		599,275
Total Liabilities and Equity	1,774,708		1,774,708		1,831,122
Company’s share of equity	263,316		263,316		278,745
Net excess of cost of investments over the net book value of underlying net assets (net of accumulated depreciation of $1,168 and $783, respectively)	(14,451)		(14,451)		(14,827)
Carrying value of investments in unconsolidated entities	248,865		248,865		263,918
Statements of Operations:
Revenues	48,036	57,566	148,760	168,863
Expenses:
Equity Method Investments, Interest Expense and Loan Cost Amortization	6,713	12,399	31,718	38,344
Depreciation and amortization	23,215	18,590	56,978	51,438
Operating expenses, ground rent and general and administrative expenses	22,602	19,098	60,678	55,121
Total expenses	52,530	50,087	149,374	144,903
Net income (loss)	4,494	(7,479)	614	(23,960)
Fair Value, Measurements, Nonrecurring [Member] | Unconsolidated Entities [Member]
Schedule of Equity Method Investments [Line Items]
Accumulated Depreciation of Investments over Book Value	1,168		1,168		783
Depreciation	129	125	385	400
Impairment Gain (Loss) on Investment Properties	$ 0	$ 5,528	$ 0	$ 6,532