Identified Intangible Assets and Intangible Liabilities (Details) (USD $) In Thousands, unless otherwise specified			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Below Market Leases Net Of Above Market Leases [Member]	Mar. 31, 2012 Below Market Leases Net Of Above Market Leases [Member]	Mar. 31, 2013 Other Identified Intangible Assets [Member]	Mar. 31, 2012 Other Identified Intangible Assets [Member]	Mar. 31, 2013 Tenant Under Ground Leases [Member]	Mar. 31, 2012 Tenant Under Ground Leases [Member]
Finite-Lived Intangible Assets [Line Items]
Identified intangible assets (included in other assets): Gross	$ 756,982	$ 774,200
Identified intangible assets (included in other assets): Accumulated amortization	(363,211)	(350,162)
Finite-Lived Intangible Assets, Net, Total	393,771	424,038
Identified intangible liabilities (included in deferred credit): Gross	906,705	904,640
Identified intangible liabilities (included in deferred credit): Accumulated amortization	(355,018)	(342,338)
Identified intangible liabilities (included in deferred credit): Net	551,687	562,302
Amortization of Intangible Assets			16,866	13,774	25,117	11,240	1,198	344
2014			43,255		45,044		3,526
2015			40,188		39,467		3,526
2016			38,130		21,002		3,526
2017			32,777		17,659		3,526
2018			$ 29,904		$ 12,722		$ 3,526