Identified Intangible Assets and Intangible Liabilities (Details) (USD $) In Thousands, unless otherwise specified			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Below Market Leases Net Of Above Market Leases [Member]	Sep. 30, 2011 Below Market Leases Net Of Above Market Leases [Member]	Sep. 30, 2012 Below Market Leases Net Of Above Market Leases [Member]	Sep. 30, 2011 Below Market Leases Net Of Above Market Leases [Member]	Sep. 30, 2012 Other Identified Intangible Assets [Member]	Sep. 30, 2011 Other Identified Intangible Assets [Member]	Sep. 30, 2012 Other Identified Intangible Assets [Member]	Sep. 30, 2011 Other Identified Intangible Assets [Member]	Sep. 30, 2012 Tenant Under Ground Leases [Member]	Sep. 30, 2011 Tenant Under Ground Leases [Member]	Sep. 30, 2012 Tenant Under Ground Leases [Member]	Sep. 30, 2011 Tenant Under Ground Leases [Member]
Finite Lived Intangible Assets [Line Items]
Identified intangible assets (included in other assets): Gross	$ 615,199	$ 642,471
Identified intangible assets (included in other assets): Accumulated amortization	(362,516)	(347,039)
Finite-Lived Intangible Assets, Net, Total	252,683	295,432
Identified intangible liabilities (included in deferred credit): Gross	816,774	830,411
Identified intangible liabilities (included in deferred credit): Accumulated amortization	(398,262)	(367,525)
Identified intangible liabilities (included in deferred credit): Net	418,512	462,886
Amortization of Intangible Assets			13,242	15,847	39,228	48,681	11,940	15,397	38,361	42,090	408	344	1,182	1,033
Future Amortization Expense, Year One					42,023				40,739				1,472
Future Amortization Expense, Year Two					36,603				22,450				1,457
Future Amortization Expense, Year Three					33,816				17,244				1,457
Future Amortization Expense, Year Four					31,333				14,714				1,457
Future Amortization Expense, Year Five					$ 25,841				$ 11,853				$ 1,457