Discontinued Operations and Gain on Disposition of Rental Properties (Details 3) (USD $)	3 Months Ended
Apr. 30, 2013	Apr. 30, 2012
Gain Loss on Disposition of Rental Properties
Gain on disposition of rental properties	$ 21,882,000	$ 8,879,000
Millender Center (Apartment Community) [Member]
Gain Loss on Disposition of Rental Properties
Gain on disposition of rental properties	21,660,000	0
Triple net lease property [Member]
Gain Loss on Disposition of Rental Properties
Gain on disposition of rental properties	222,000	0
Quebec Square (Specialty Retail Center) [Member]
Gain Loss on Disposition of Rental Properties
Gain on disposition of rental properties	$ 0	$ 8,879,000

Amount of gain (loss), before tax expense or benefit and not previously recognized, resulting from the sale of a business component.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 144

-Paragraph 47

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e957-107759

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 144

-Paragraph 43

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration