Accounting Policies (Details Textual) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jul. 31, 2012	Jan. 31, 2012
Accounting Policies (Textual) [Abstract]
Unrealized losses on an interest rate swap associated with office building	$ 141,840	$ 143,303
Total rate of return swap contract amount	$ 640,000
Nonrecourse Mortgage Debt [Member]
Accounting Policies (Textual) [Abstract]
All in Lender Interest Rate	6.40%
Swap Rate	5.50%
Debt instrument variable rate basis spread	0.90%
Maturity date of Swap Agreement	Sep. 01, 2017