Intangible Assets and Below Market Liabilities (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 years	Mar. 31, 2011	Dec. 31, 2011
Intangible assets and below market liabilities, net [Abstract]
Deferred financing and leasing costs, accumulated amortization	$ (67,662)		$ (63,059)
Deferred financing and leasing costs, net	129,204		128,390
Deferred Financing Costs [Member]
Intangible assets and below market liabilities, net [Abstract]
Deferred financing and leasing costs, gross	20,251		18,044
Deferred financing and leasing costs, accumulated amortization	(6,675)		(5,797)
Deferred financing and leasing costs, net	13,576		12,247
Amortization of intangible assets and below market liabilities [Abstract]
Amortization of intangible assets	902	821
Scheduled future amortization of intangible assets and below market liabilities [Abstract]
April 1, 2012 through December 31, 2012	2,835
2013	3,306
2014	3,004
2015	2,391
2016	1,020
Thereafter	1,020
Total future amortization of intangible assets and below market liabilities	13,576
Weighted average remaining amortization periods for intangible assets and below market liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	4.0
Deferred Leasing Costs [Member]
Intangible assets and below market liabilities, net [Abstract]
Deferred financing and leasing costs, gross	176,615		173,405
Deferred financing and leasing costs, accumulated amortization	(60,987)		(57,262)
Deferred financing and leasing costs, net	115,628		116,143
Amortization of intangible assets and below market liabilities [Abstract]
Amortization of intangible assets	6,440	4,356
Scheduled future amortization of intangible assets and below market liabilities [Abstract]
April 1, 2012 through December 31, 2012	19,281
2013	21,690
2014	17,497
2015	13,476
2016	10,175
Thereafter	23,172
Total future amortization of intangible assets and below market liabilities	105,291
Weighted average remaining amortization periods for intangible assets and below market liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	6.2
Deferred Lease Incentives [Member]
Amortization of intangible assets and below market liabilities [Abstract]
Amortization of intangible assets	343	338
Scheduled future amortization of intangible assets and below market liabilities [Abstract]
April 1, 2012 through December 31, 2012	981
2013	1,154
2014	992
2015	771
2016	600
Thereafter	2,341
Total future amortization of intangible assets and below market liabilities	6,839
Weighted average remaining amortization periods for intangible assets and below market liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	8.0
Acquisition-Related Intangible Assets [Member]
Amortization of intangible assets and below market liabilities [Abstract]
Amortization of intangible assets	270	186
Scheduled future amortization of intangible assets and below market liabilities [Abstract]
April 1, 2012 through December 31, 2012	788
2013	820
2014	526
2015	341
2016	281
Thereafter	742
Total future amortization of intangible assets and below market liabilities	3,498
Weighted average remaining amortization periods for intangible assets and below market liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	5.7
Acquisition-Related Below Market Liabilities [Member]
Intangible assets and below market liabilities, net [Abstract]
Acquisition-related below market liabilities, gross	16,390		16,441
Acquisiton-related below market liabilities, accumulated amortization	(1,457)		(971)
Acquisition-related below market liabilities, net	14,933		15,470
Amortization of intangible assets and below market liabilities [Abstract]
Amortization of acquisition-related below market liabilities	(544)	(25)
Scheduled future amortization of intangible assets and below market liabilities [Abstract]
April 1, 2012 through December 31, 2012	(1,589)
2013	(2,093)
2014	(2,019)
2015	(1,807)
2016	(1,511)
Thereafter	(5,914)
Total future amortization of intangible assets and below market liabilities	$ (14,933)
Weighted average remaining amortization periods for intangible assets and below market liabilities [Abstract]
Finite-lived below market liabilities, average useful life (in years)	8.4