Identified Intangible Assets and Intangible Liabilities (Details) (USD $) In Thousands, unless otherwise specified			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Below Market Leases Net Of Above Market Leases [Member]	Jun. 30, 2011 Below Market Leases Net Of Above Market Leases [Member]	Jun. 30, 2012 Below Market Leases Net Of Above Market Leases [Member]	Jun. 30, 2011 Below Market Leases Net Of Above Market Leases [Member]	Jun. 30, 2012 Other Identified Intangible Assets [Member]	Jun. 30, 2011 Other Identified Intangible Assets [Member]	Jun. 30, 2012 Other Identified Intangible Assets [Member]	Jun. 30, 2011 Other Identified Intangible Assets [Member]	Jun. 30, 2012 Tenant Under Ground Leases [Member]	Jun. 30, 2011 Tenant Under Ground Leases [Member]	Jun. 30, 2012 Tenant Under Ground Leases [Member]	Jun. 30, 2011 Tenant Under Ground Leases [Member]
Finite Lived Intangible Assets [Line Items]
Identified intangible assets (included in other assets): Gross	$ 615,446	$ 642,565
Identified intangible assets (included in other assets): Accumulated amortization	(349,060)	(347,105)
Finite-Lived Intangible Assets, Net, Total	266,386	295,460
Identified intangible liabilities (included in deferred credit): Gross	819,397	830,411
Identified intangible liabilities (included in deferred credit): Accumulated amortization	(386,293)	(367,525)
Identified intangible liabilities (included in deferred credit): Net	433,104	462,886
Amortization of Intangible Assets			12,411	16,427	25,986	32,772	14,492	13,060	26,424	26,715	408	344	774	688
Future Amortization Expense, Year One					43,597				40,047				1,472
Future Amortization Expense, Year Two					37,331				21,670				1,457
Future Amortization Expense, Year Three					34,260				16,700				1,457
Future Amortization Expense, Year Four					31,212				14,173				1,457
Future Amortization Expense, Year Five					$ 25,704				$ 11,571				$ 1,457