Discontinued Operations and Gain (Loss) on Disposition of Rental Properties (Details 2) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2011	Jul. 31, 2010
Gain Loss on Disposition of Rental Properties
Gain (loss) on disposition of rental properties	$ 111,264	$ 6,204	$ 121,695	$ 6,204
Waterfront Station - East 4th & West 4th Buildings [Member]
Gain Loss on Disposition of Rental Properties
Gain (loss) on disposition of rental properties	111,738		111,738
Charleston Marriott hotel [Member]
Gain Loss on Disposition of Rental Properties
Gain (loss) on disposition of rental properties	(474)		9,957
101 San Fernando [Member]
Gain Loss on Disposition of Rental Properties
Gain (loss) on disposition of rental properties		$ 6,204		$ 6,204