Accounting for the Impairment or Disposal of Long-Lived Assets - Asset Impairments in Reportable Segments (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012		Dec. 31, 2011
Schedule of Real Estate Impairment [Line Items]
Asset Impairment Charges	$ 1,904,000	$ 6,851,000		$ 7,830,000
Land Impairment	248,000
Impairment Losses Related to Real Estate Partnerships	784,000	4,600,000
Impairment of Real Estate	872,000	2,300,000		7,900,000
Chicago Milwaukee [Member]
Schedule of Real Estate Impairment [Line Items]
Asset Impairment Charges	0	514,000		5,985,000
Houston [Member]
Schedule of Real Estate Impairment [Line Items]
Asset Impairment Charges	0	0		6,000
Carolinas [Member]
Schedule of Real Estate Impairment [Line Items]
Asset Impairment Charges	0	36,000		670,000
Industrial Other [Member]
Schedule of Real Estate Impairment [Line Items]
Asset Impairment Charges	0	29,000		538,000
South Florida [Member]
Schedule of Real Estate Impairment [Line Items]
Asset Impairment Charges	0	(51,000)	[1]	160,000
Richmond Hampton Roads [Member]
Schedule of Real Estate Impairment [Line Items]
Asset Impairment Charges	0	27,000		501,000
United Kingdom [Member]
Schedule of Real Estate Impairment [Line Items]
Asset Impairment Charges	784,000	4,597,000		0
Other Segments [Member]
Schedule of Real Estate Impairment [Line Items]
Asset Impairment Charges	1,120,000	0		(30,000)	[1]
Southeastern PA [Member]
Schedule of Real Estate Impairment [Line Items]
Asset Impairment Charges	$ 0	$ 1,699,000		$ 0

[1] Represents recovery of estimated sales costs on properties sold.