Identified Intangible Assets and Intangible Liabilities (Details) (USD $) In Thousands			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2011 Below Market Leases Net Of Above Market Leases [Member]	Sep. 30, 2010 Below Market Leases Net Of Above Market Leases [Member]	Sep. 30, 2011 Below Market Leases Net Of Above Market Leases [Member]	Sep. 30, 2010 Below Market Leases Net Of Above Market Leases [Member]	Sep. 30, 2011 Other Identified Intangible Assets [Member]	Sep. 30, 2010 Other Identified Intangible Assets [Member]	Sep. 30, 2011 Other Identified Intangible Assets [Member]	Sep. 30, 2010 Other Identified Intangible Assets [Member]	Sep. 30, 2011 Tenant Under Ground Leases [Member]	Sep. 30, 2010 Tenant Under Ground Leases [Member]	Sep. 30, 2011 Tenant Under Ground Leases [Member]	Sep. 30, 2010 Tenant Under Ground Leases [Member]
Finite Lived Intangible Assets [Line Items]
Identified intangible assets (included in other assets): Gross	$ 690,996	$ 681,270
Identified intangible assets (included in other assets): Accumulated amortization	(356,118)	(335,113)
Finite-Lived Intangible Assets, Net, Total	334,878	346,157
Identified intangible liabilities (included in deferred credit): Gross	861,696	856,689
Identified intangible liabilities (included in deferred credit): Accumulated amortization	(380,198)	(335,317)
Identified intangible liabilities (included in deferred credit): Net	481,498	521,372
Amortization of Intangible Assets			16,100	16,756	49,387	48,476	16,059	15,032	43,782	45,317	344	539	1,033	1,618
Future Amortization Expense, Year One					51,092				47,168				1,377
Future Amortization Expense, Year Two					43,174				39,703				1,377
Future Amortization Expense, Year Three					37,419				21,398				1,377
Future Amortization Expense, Year Four					34,673				16,471				1,377
Future Amortization Expense, Year Five					$ 31,281				$ 13,924				$ 1,377