Impairment of Real Estate, Impairment of Unconsolidated Entities and Write-Off of Abandoned Development Projects (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012	Jul. 31, 2011
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	$ 2,908	$ 235	$ 4,289	$ 5,070
Impairment of unconsolidated entities	390	0	390	0
disposal group including discontinued operations impairment of real estate	261	0	261	0
Write-off of abandoned development projects	13,212	5,088	13,659	5,245
White Oak Village [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	1,566	0	1,566	0
Portage, MI [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	882	0	2,263	3,435
Other [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	$ 460	$ 235	$ 460	$ 1,635