Acquisitions, Dispositions, Leasing and Financing Activities (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Intangible assets acquired and intangible liabilities assumed
Intangible assets carrying value	$ 17,810
Intangible assets acquired and intangible liabilities assumed, weighted average amortization period	9 years
In place lease intangibles [Member]
Intangible assets acquired and intangible liabilities assumed
Intangible assets carrying value	6,542
Intangible assets acquired and intangible liabilities assumed, weighted average amortization period	6 years 2 months 12 days
Above market lease intangibles [Member]
Intangible assets acquired and intangible liabilities assumed
Intangible assets carrying value	2,867
Intangible assets acquired and intangible liabilities assumed, weighted average amortization period	5 years 9 months 18 days
Tenant relationship value [Member]
Intangible assets acquired and intangible liabilities assumed
Intangible assets carrying value	7,388
Intangible assets acquired and intangible liabilities assumed, weighted average amortization period	13 years 3 months 18 days
Lease commissions, legal and marketing fees [Member]
Intangible assets acquired and intangible liabilities assumed
Intangible assets carrying value	1,013
Intangible assets acquired and intangible liabilities assumed, weighted average amortization period	5 years 4 months 24 days
Below market lease intangibles [Member]
Intangible assets acquired and intangible liabilities assumed
Intangible assets carrying value	$ (620)
Intangible assets acquired and intangible liabilities assumed, weighted average amortization period	4 years 2 months 12 days