Impairment of Real Estate, Impairment of Unconsolidated Entities and Write-Off of Abandoned Development Projects(Detail Textuals) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013 purchaseoffers	Jan. 31, 2012	Jan. 31, 2011
Impairment of real estate impairment of unconsolidated entities and write off of abandoned development projects [Line Items]
Impairment of real estate	$ 30,660	$ 235	$ 4,763
Impairment of real estate included in discontinued operations	4,254	13,692	81,643
Gain (loss) on disposition of rental properties	100,900	133,554	51,303
Number of bona fide purchase offers	5
Impairment of unconsolidated entities	390	40,284	72,459
Write-off of abandoned development projects	26,850	8,838	9,195
Halle Building (Office Building) [Member]
Impairment of real estate impairment of unconsolidated entities and write off of abandoned development projects [Line Items]
Carrying value of real estate, fair value	10,500
Impairment of real estate	30,200	0	0
250 Huron (Office Building) [Member]
Impairment of real estate impairment of unconsolidated entities and write off of abandoned development projects [Line Items]
Impairment of real estate included in discontinued operations	0	10,257	2,040
Simi Valley Town Center (Regional Mall) [Member]
Impairment of real estate impairment of unconsolidated entities and write off of abandoned development projects [Line Items]
Impairment of real estate included in discontinued operations	0	0	76,962
Village at Gulfstream Park (Specialty Retail Center) [Member]
Impairment of real estate impairment of unconsolidated entities and write off of abandoned development projects [Line Items]
Impairment of unconsolidated entities	0	35,674	35,000
250 Huron (Office Building) [Member]
Impairment of real estate impairment of unconsolidated entities and write off of abandoned development projects [Line Items]
Gain (loss) on disposition of rental properties	0	9,428	0
Simi Valley Town Center (Regional Mall) [Member]
Impairment of real estate impairment of unconsolidated entities and write off of abandoned development projects [Line Items]
Gain (loss) on disposition of rental properties	$ 0	$ 0	$ 46,802