Investment in Unconsolidated Joint Ventures (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Assets
Commercial real estate property, net	$ 10,586,513		$ 10,687,540
Other assets	815,873		750,123
Liabilities and members' equity
Mortgages and other loans payable	4,971,022		4,860,578
Company's investments in unconsolidated joint ventures	1,061,704		1,113,218
Combined statements of income for the unconsolidated joint ventures
Operating expenses	73,486	71,170
Ground rent	8,033	8,128
Real estate taxes	55,316	52,444
Interest expense, net of interest income	80,180	80,775
Amortization of deferred financing costs	3,868	4,463
Transaction related costs, net of recoveries	2,474	1,358
Depreciation and amortization	89,379	78,623
Total expenses	335,993	318,028
Company's equity in net income from unconsolidated joint ventures	6,128	5,073
Joint Venture
Assets
Commercial real estate property, net	6,356,664		6,846,021
Other assets	691,636		827,282
Total assets	7,048,300		7,673,303
Liabilities and members' equity
Mortgages and other loans payable	4,577,178		5,066,710
Other liabilities	580,870		596,960
Members' equity	1,890,252		2,009,633
Total liabilities and members' equity	7,048,300		7,673,303
Company's investments in unconsolidated joint ventures	1,061,704		1,113,218
Combined statements of income for the unconsolidated joint ventures
Total revenues	161,138	151,231
Operating expenses	26,683	28,611
Ground rent	2,025	657
Real estate taxes	16,936	17,305
Interest expense, net of interest income	52,336	56,407
Amortization of deferred financing costs	4,633	4,283
Transaction related costs, net of recoveries	271	0
Depreciation and amortization	45,604	42,611
Total expenses	148,488	149,874
Loss on early extinguishment of debt	(3,197)	0
Net income before gain on sale	9,453	1,357
Company's equity in net income from unconsolidated joint ventures	$ 6,128	$ 5,073