Impairment of Real Estate Impairment of Unconsolidated Entities Write-off of Abandoned Development Projects and Gain (Loss) on Extinguishment of Debt (Details Textual) (USD $)	12 Months Ended
	Jan. 31, 2012 Project Land	Jan. 31, 2011	Jan. 31, 2010
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	$ 119,324,000	$ 4,763,000	$ 8,907,000
Gain (Loss) on disposition of rental properties	133,554,000	51,303,000	5,720,000
Number of active land projects	35
Extinguishment of Debt [Line Items]
Gain (Loss) on early extinguishment of debt	9,590,000	(21,035,000)	36,569,000
Impairment of Investments [Line Items]
Impairment of unconsolidated entities	82,186,000	72,459,000	36,356,000
Number of active land projects accounted for on equity method	18
Impairment of Real Estate, Impairment of Unconsolidated Entities, Write Off of Abandoned Development Projects and Gain on Early Extinguishment of Debt (Textual) [Abstract]
Write-off of abandoned development projects	8,838,000	9,195,000	20,739,000
Write-offs of abandoned development projects related to unconsolidated entities	0	3,045,000	304,000
Village at Gulfstream Park (Retail Center) [Member]
Impairment of Investments [Line Items]
Impairment of unconsolidated entities	35,674,000	35,000,000
Land development projects [Member]
Impairment of Investments [Line Items]
Impairment of unconsolidated entities	41,902,000
5.000% Convertible Senior Notes due 2016 [Member]
Extinguishment of Debt [Line Items]
Gain (Loss) on early extinguishment of debt	(10,800,000)
Gain (Loss) on exchange of notes for shares		(31,689,000)
Avenue at Tower City Center [Member]
Extinguishment of Debt [Line Items]
Gain (Loss) on early extinguishment of debt	5,329,000
2011, 2015 and 2017 Senior Notes [Member]
Extinguishment of Debt [Line Items]
Gain (Loss) on exchange of notes for shares		6,297,000
2011 and 2017 Senior Notes [Member]
Extinguishment of Debt [Line Items]
Gain (Loss) on early extinguishment of debt		1,896,000
Botanica on the Green and Crescent Flats [Member]
Extinguishment of Debt [Line Items]
Gain (Loss) on early extinguishment of debt		2,472,000
Mixed-use development project in Las Vegas, Nevada [Member]
Extinguishment of Debt [Line Items]
Loss on extinguishment of debt	15,101,000
Simi Valley Town Center (Regional Mall) [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate		76,962,000
Gain (Loss) on disposition of rental properties		46,802,000
250 Huron (Office Building) [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	10,257,000	2,040,000
Gain (Loss) on disposition of rental properties	9,428,000
Land held for divestiture [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	$ 115,654,000