Summary of Significant Accounting Policies (Details Textual 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Accounting Policies (Textual) [Abstract]
Unrealized losses on an interest rate swap associated with office building	$ 126,506	$ 143,303	$ 102,387
Total rate of return swap contract amount	640,000
All in lender interest rate on mortgage	interest rate of 6.40% (5.50% swap rate plus 0.90% lender spread	interest rate of 6.40% (5.50% swap rate plus 0.90% lender spread	interest rate of 6.40% (5.50% swap rate plus 0.90% lender spread
Tax Credits (Textuals) [Abstract]
Minimum Compliance Regulation on Tax Credit	0 years
Maximum Compliance Regulation on Tax Credit	7 years
Income related to the sale of tax credits	$ 20,800	$ 27,296	$ 31,979
Nonrecourse Mortgage Debt [Member]
Accounting Policies (Textual) [Abstract]
All in Lender Interest Rate	6.40%
Interest Rate	5.50%
Debt instrument variable rate basis spread	0.90%
Maturity date of Swap Agreement	Sep. 01, 2017