Identified Intangible Assets and Intangible Liabilities (Details) (USD $) In Thousands			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Below Market Leases Net Of Above Market Leases [Member]	Jun. 30, 2010 Below Market Leases Net Of Above Market Leases [Member]	Jun. 30, 2011 Below Market Leases Net Of Above Market Leases [Member]	Jun. 30, 2010 Below Market Leases Net Of Above Market Leases [Member]	Jun. 30, 2011 Other Identified Intangible Assets [Member]	Jun. 30, 2010 Other Identified Intangible Assets [Member]	Jun. 30, 2011 Other Identified Intangible Assets [Member]	Jun. 30, 2010 Other Identified Intangible Assets [Member]	Jun. 30, 2011 Tenant Under Ground Leases [Member]	Jun. 30, 2010 Tenant Under Ground Leases [Member]	Jun. 30, 2011 Tenant Under Ground Leases [Member]	Jun. 30, 2010 Tenant Under Ground Leases [Member]
Finite Lived Intangible Assets [Line Items]
Identified intangible assets (included in other assets): Gross	$ 680,598	$ 687,253
Identified intangible assets (included in other assets): Accumulated amortization	(363,341)	(338,508)
Finite-Lived Intangible Assets, Net, Total	317,257	348,745
Identified intangible liabilities (included in deferred credit): Gross	877,836	870,623
Identified intangible liabilities (included in deferred credit): Accumulated amortization	(374,438)	(341,718)
Identified intangible liabilities (included in deferred credit): Net	503,398	528,905
Amortization of Intangible Assets			16,812	16,284	33,571	32,055	13,623	15,757	27,885	30,610	334	509	648	1,018
Future Amortization Expense, Year One					52,025				44,777				1,377
Future Amortization Expense, Year Two					44,095				37,281				1,377
Future Amortization Expense, Year Three					38,240				18,885				1,377
Future Amortization Expense, Year Four					35,472				13,929				1,377
Future Amortization Expense, Year Five					$ 32,093				$ 11,325				$ 1,377