Accounting Policies (Details 1) (USD $) In Thousands	Jul. 31, 2011	Jan. 31, 2011
The schedule of fair value of nonrecourse mortgage debt and notes payable, bank revolving credit facility and senior and subordinated debt
Carrying Value	$ 6,706,518	$ 8,118,053
Fair Value	7,001,037	8,322,294
Fixed Interest Rate [Member]
The schedule of fair value of nonrecourse mortgage debt and notes payable, bank revolving credit facility and senior and subordinated debt
Carrying Value	4,462,968	4,649,129
Fair Value	4,691,889	4,802,728
Variable Interest Rate [Member]
The schedule of fair value of nonrecourse mortgage debt and notes payable, bank revolving credit facility and senior and subordinated debt
Carrying Value	2,243,550	3,468,924
Fair Value	$ 2,309,148	$ 3,519,566