Discontinued Operations and Gain (Loss) on Disposition of Rental Properties (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011	Oct. 31, 2010
Gain Loss on Disposition of Rental Properties
Gain (loss) on disposition of rental properties	$ 0	$ (1,428)	$ 121,695	$ 4,776
Waterfront Station - East 4th & West 4th Buildings [Member]
Gain Loss on Disposition of Rental Properties
Gain (loss) on disposition of rental properties	0		111,738
Charleston Marriott hotel [Member]
Gain Loss on Disposition of Rental Properties
Gain (loss) on disposition of rental properties	0		9,957
Saddle Rock Village [Member]
Gain Loss on Disposition of Rental Properties
Gain (loss) on disposition of rental properties	0	(1,428)		(1,428)
101 San Fernando [Member]
Gain Loss on Disposition of Rental Properties
Gain (loss) on disposition of rental properties	$ 0			$ 6,204