Investment in Unconsolidated Joint Ventures (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assets
Commercial real estate property, net	$ 10,687,540	$ 10,269,630
Other assets	750,123	718,326
Liabilities and members' equity
Mortgages and other loans payable	4,860,578	4,615,464
Company's investments in unconsolidated joint ventures	1,113,218	1,032,243
Combined statements of income for the unconsolidated joint ventures
Operating expenses	293,514	292,392	257,938
Ground rent	39,926	37,866	32,919
Real estate taxes	218,832	209,337	173,154
Interest expense, net of interest income	330,215	329,897	285,248
Amortization of deferred financing costs	16,695	19,450	14,108
Transaction related costs, net of recoveries	3,987	5,625	5,561
Depreciation and amortization	357,599	351,539	292,311
Total expenses	1,327,053	1,303,708	1,127,059
Company's equity in net income from unconsolidated joint ventures	9,921	76,418	1,583
Joint venture
Assets
Commercial real estate property, net	6,846,021	6,910,991
Other assets	827,282	728,113
Total assets	7,673,303	7,639,104
Liabilities and members' equity
Mortgages and other loans payable	5,066,710	5,358,048
Other liabilities	596,960	406,929
Members' equity	2,009,633	1,874,127
Total liabilities and members' equity	7,673,303	7,639,104
Company's investments in unconsolidated joint ventures	1,113,218	1,032,243
Combined statements of income for the unconsolidated joint ventures
Total revenues	628,649	511,157	480,935
Operating expenses	114,633	80,722	71,830
Ground rent	2,863	2,975	3,683
Real estate taxes	71,755	53,613	51,511
Interest expense, net of interest income	225,765	221,476	210,489
Amortization of deferred financing costs	17,092	9,739	12,911
Transaction related costs, net of recoveries	808	2,044	2,665
Depreciation and amortization	192,504	166,336	137,070
Total expenses	625,420	536,905	490,159
Gain on early extinguishment of debt	0	21,421	0
Net income (loss) before gain on sale	3,229	(4,327)	(9,224)
Company's equity in net income from unconsolidated joint ventures	$ 9,921	$ 76,418	$ 1,583