Discontinued Operations and Gain on Disposition of Rental Properties (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012	Jul. 31, 2011
Gain Loss on Disposition of Rental Properties
Gain (Loss) on disposition of rental properties	$ 0	$ 111,264	$ 8,879	$ 121,695
Quebec Square (Specialty Retail Center) [Member]
Gain Loss on Disposition of Rental Properties
Gain (Loss) on disposition of rental properties	0	0	8,879	0
Waterfront Station - East 4th and West 4th Buildings [Member]
Gain Loss on Disposition of Rental Properties
Gain (Loss) on disposition of rental properties	0	111,738	0	111,738
Charleston Marriott (Hotel) [Member]
Gain Loss on Disposition of Rental Properties
Gain (Loss) on disposition of rental properties	$ 0	$ (474)	$ 0	$ 9,957