Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of Significant Accounting Policies (Textual) [Abstract]
Asset Impairment Charges	$ 913	$ 14,934	$ 25,639
Straight Line Rent	(403)	(101)	751
Amortization of above and below Market Leases	882	2,396	1,783
Finite-Lived Intangible Asset, Useful Life	3 years 1 month
Finite-Lived Intangible Assets, Accumulated Amortization	26,515	34,100
Finite-Lived intangible liability, Accumulated Amortization	5,465	5,685
Total Revenue From Foreign Investments	3,874	4,462	4,274
Total Revenue from US Investments	78,407	92,889	93,068
Total Assets From Foreign Investments	40,917	39,663
Total Assets from US Investments	801,117	795,247
Summary of Significant Accounting Policies (Additional Textual) [Abstract]
Allowance for doubtful accounts	570	731
Accumulated amortization of Deferred expenses	4,013	4,022
Level two [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Mortgage notes payable, fair value	17,136	2,224
Maximum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Consolidation of variable interest entities, ownership percentage	100.00%
In-Place Leases [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Acquired In-Place Leases Next Twelve Months	8,047
Acquired Above Market Leases Next Twelve Months	451
Below Market Ground Lease Next Twelve Months	146
Acquired Below Market Leases Next Twelve Months	(2,605)
Acquired In-Place Leases Year Two	7,491
Acquired Above Market Leases Year Two	357
Below Market Ground Leases Year Two	146
Acquired Below Market Leases Year Two	(2,083)
Acquired In-Place Leases Year Three	7,242
Acquired Above Market Leases Year Three	287
Below Market Ground Leases Year Three	146
Acquired Below Market Leases Year Three	(1,611)
Acquired In-Place Leases Year Four	2,999
Acquired Above Market Leases Year Four	145
Below Market Ground Leases Year Four	146
Acquired Below Market Leases Year Four	(1,366)
Acquired In-Place Leases Year Five	1,573
Acquired Above Market Leases Year Five	76
Below Market Ground Leases Year Five	146
Acquired Below Market Leases Year Five	(730)
Acquired In-Place Leases After Year Five	2,853
Acquired Above Market Leases After Year Five	25
Below Market Ground Leases After Year Five	8,849
Acquired Below Market Leases After Year Five	(1,685)
Acquired In Place Leases	30,205
Acquired Above Market Leases	1,341
Below Market Ground Leases	9,579
Acquired Below Market Leases	$ (10,080)
In-Place Leases [Member] | Minimum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Finite-Lived Intangible Asset, Useful Life	1 year
In-Place Leases [Member] | Maximum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Finite-Lived Intangible Asset, Useful Life	29 years
Building [Member] | Minimum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Property, Plant and Equipment, Useful Life	40 years
Building [Member] | Maximum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Property, Plant and Equipment, Useful Life	50 years
Equipment [Member] | Minimum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Property, Plant and Equipment, Useful Life	2 years
Equipment [Member] | Maximum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Property, Plant and Equipment, Useful Life	10 years