Discontinued Operations and Gain on Disposition of Rental Properties (Details 1)	3 Months Ended
	Apr. 30, 2013 Millender Center [Member] apartmentunit	Apr. 30, 2012 Millender Center [Member]	Apr. 30, 2013 Emerald Palms [Member] apartmentunit	Apr. 30, 2012 Emerald Palms [Member]	Apr. 30, 2013 Southfield [Member] apartmentunit	Apr. 30, 2012 Southfield [Member]	Apr. 30, 2013 Fairmont Plaza [Member] sqft	Apr. 30, 2012 Fairmont Plaza [Member]	Apr. 30, 2013 White Oak Village [Member] sqft	Apr. 30, 2012 White Oak Village [Member]	Apr. 30, 2013 Quebec Square [Member] sqft	Apr. 30, 2012 Quebec Square [Member]	Apr. 30, 2013 Six triple net lease properties [Member] sqft		Apr. 30, 2012 Six triple net lease properties [Member]	Apr. 30, 2013 One triple net lease property [Member] property		Oct. 31, 2012 Three triple net lease properties [Member] property		Jul. 31, 2012 Two triple net lease properties [Member] property
Summary of rental properties included in discontinued operations
Location	Detroit, Michigan		Miami, Florida		Whitemarsh, Maryland		San Jose, California		Richmond, Virginia		Denver, Colorado		Various
Square Feet							335,000		843,000		739,000		287,000
Number of Units	339		505		212
Period Disposed	Q1-2013		Q4-2012		Q3-2012		Q4-2012		Q3-2012		Q1-2012		Various	[1]
Period Status	Yes	Yes	0	Yes	0	Yes	0	Yes	0	Yes	0	Yes	Yes		Yes
Number of triple net lease properties disposed of																1	[1]	3	[1]	2	[1]

[1] Includes one triple net lease property disposed of during Q1-2013, three triple net lease properties disposed of during Q3-2012 and two triple net lease properties disposed of during Q2-2012.