Identified Intangible Assets and Intangible Liabilities (Details) (USD $) In Thousands, unless otherwise specified			3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Below Market Leases Net Of Above Market Leases [Member]	Mar. 31, 2011 Below Market Leases Net Of Above Market Leases [Member]	Mar. 31, 2012 Other Identified Intangible Assets [Member]	Mar. 31, 2011 Other Identified Intangible Assets [Member]	Mar. 31, 2012 Tenant Under Ground Leases [Member]	Mar. 31, 2011 Tenant Under Ground Leases [Member]
Finite Lived Intangible Assets [Line Items]
Identified intangible assets (included in other assets): Gross	$ 666,241	$ 679,648
Identified intangible assets (included in other assets): Accumulated amortization	(361,856)	(359,944)
Finite-Lived Intangible Assets, Net, Total	304,385	319,704
Identified intangible liabilities (included in deferred credit): Gross	837,729	841,440
Identified intangible liabilities (included in deferred credit): Accumulated amortization	(385,886)	(374,253)
Identified intangible liabilities (included in deferred credit): Net	451,843	467,187
Amortization of Intangible Assets			13,813	16,606	12,366	14,155	344	344
Future Amortization Expense, Year One			44,133		40,162		1,377
Future Amortization Expense, Year Two			37,504		21,758		1,377
Future Amortization Expense, Year Three			34,399		16,757		1,377
Future Amortization Expense, Year Four			31,339		14,156		1,377
Future Amortization Expense, Year Five			$ 25,819		$ 11,709		$ 1,377