Accounting Policies (Details Textual 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Apr. 30, 2013	Jan. 31, 2013
Accounting Policies (Textual) [Abstract]
Unrealized losses on an interest rate swap associated with office building	$ 126,171	$ 126,506
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
All-in lender interest rate on mortgage	interest rate of 6.40% (5.50% swap rate plus 0.90% lender spread)