Impairment of Real Estate, Impairment of Unconsolidated Entities, Write-Off of Abandoned Development Projects and Gain (Loss) on Extinguishment of Debt (Details 2) (USD $)	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities	$ 82,186,000	$ 72,459,000	$ 36,356,000
Other [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities		6,992,000	8,889,000
Pittsburgh Peripheral (Commercial Group Land Project) [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities			7,217,000
Millender Center [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities			10,317,000
Classic Residence by Hyatt (Supported-Living Apartments) [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities			3,152,000
Equity method investments in land entities [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities	41,902,000
Four Museum Park properties [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities		18,311,000
Commercial land and development rights [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities	4,610,000
818 Mission Street [Member] | Office Buildings [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities		4,018,000
Bulletin Building [Member] | Office Buildings [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities		3,543,000
Village at Gulfstream Park [Member] | Specialty Retail Centers [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities	35,674,000	35,000,000
Metreon [Member] | Specialty Retail Centers [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities		4,595,000
Uptown Apartments [Member] | Apartment Communities [Member]
Summary of Company's impairment of unconsolidated entities
Impairment of unconsolidated entities			$ 6,781,000