Discontinued Operations and Gain on Disposition of Rental Properties (Details 1)	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended			3 Months Ended
	Oct. 31, 2013 Millender Center [Member]	Oct. 31, 2012 Millender Center [Member]	Oct. 31, 2013 Millender Center [Member] apartmentunit	Oct. 31, 2012 Millender Center [Member]	Oct. 31, 2013 Emerald Palms [Member]	Oct. 31, 2012 Emerald Palms [Member]	Oct. 31, 2013 Emerald Palms [Member] apartmentunit	Oct. 31, 2012 Emerald Palms [Member]	Oct. 31, 2013 Southfield [Member]	Oct. 31, 2012 Southfield [Member]	Oct. 31, 2013 Southfield [Member] apartmentunit	Oct. 31, 2012 Southfield [Member]	Oct. 31, 2013 Colorado Studios [Member]	Oct. 31, 2012 Colorado Studios [Member]	Oct. 31, 2013 Colorado Studios [Member] sqft	Oct. 31, 2012 Colorado Studios [Member]	Oct. 31, 2013 Higbee Building [Member]	Oct. 31, 2012 Higbee Building [Member]	Oct. 31, 2013 Higbee Building [Member] sqft	Oct. 31, 2012 Higbee Building [Member]	Oct. 31, 2013 Sheraton Station Square [Member]	Oct. 31, 2012 Sheraton Station Square [Member]	Oct. 31, 2013 Sheraton Station Square [Member] room	Oct. 31, 2012 Sheraton Station Square [Member]	Oct. 31, 2013 Fairmont Plaza [Member]	Oct. 31, 2012 Fairmont Plaza [Member]	Oct. 31, 2013 Fairmont Plaza [Member] sqft	Oct. 31, 2012 Fairmont Plaza [Member]	Oct. 31, 2013 White Oak Village [Member]	Oct. 31, 2012 White Oak Village [Member]	Oct. 31, 2013 White Oak Village [Member] sqft	Oct. 31, 2012 White Oak Village [Member]	Oct. 31, 2013 Quebec Square [Member]	Oct. 31, 2012 Quebec Square [Member]	Oct. 31, 2013 Quebec Square [Member] sqft	Oct. 31, 2012 Quebec Square [Member]	Oct. 31, 2013 Six triple net lease properties [Member]	Oct. 31, 2012 Six triple net lease properties [Member]	Oct. 31, 2013 Six triple net lease properties [Member] sqft		Oct. 31, 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				Denver, Colorado				Cleveland, Ohio				Pittsburgh, Pennsylvania				San Jose, California				Richmond, Virginia				Denver, Colorado				Various
Square feet															75,000				815,000								335,000				843,000				739,000				287,000
Number of units/rooms			339				505				212												399
Period disposed			Q1-2013				Q4-2012				Q3-2012				Q3-2013				Q2-2013				Q2-2013				Q4-2012				Q3-2012				Q1-2012				Various	[1]
Period status	0	Yes	Yes	Yes	0	Yes	0	Yes	0	Yes	0	Yes	Yes	Yes	Yes	Yes	0	Yes	Yes	Yes	0	Yes	Yes	Yes	0	Yes	0	Yes	0	Yes	0	Yes	0	0	0	Yes	0	Yes	Yes		Yes
Number of triple net lease properties disposed of																																										1	3	2

[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.