Summary of Significant Accounting Policies (Details Textual 1) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2013
Variable Interest Entity [Line Items]
Maximum loss exposure for unconsolidated variable interest entities	64
Collateralized borrowings of variable interest entities	29
Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of variable interest entities	31
Number of properties representing variable interest entities	22
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of variable interest entities	59
Residential Group [Member] | Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of variable interest entities	19
Number of properties representing variable interest entities	10
Commercial Group [Member] | Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of variable interest entities	12
Number of properties representing variable interest entities	12
Minimum [Member]
Revenue Recognition [Abstract]
Lease terms of tenants in retail centers and office buildings	1 year
Arena founding partner and sponsor agreement term	1 year
Arena suite license agreement term	1 year
Maximum [Member]
Revenue Recognition [Abstract]
Lease terms of tenants in retail centers and office buildings	30 years
Arena founding partner and sponsor agreement term	7 years
Arena suite license agreement term	7 years
Arena [Member]
Revenue Recognition [Abstract]
Naming rights agreement contract term	20 years