Fair Value Measurements (Details 2) (Fair value measurement, recurring basis [Member], USD $)	3 Months Ended
	Apr. 30, 2013		Apr. 30, 2012
Fair value of financial instruments measured on a recurring basis
Redeemable noncontrolling interest	$ (238,942,000)		$ (239,136,000)
Fair value valuation technique credit valuation adjustment of interest rate swap	Potential future exposure
Fair value valuation technique of total return swap	Bond quote
Fair value valuation technique adjustment to borrowings subject to total rate of return swap	Bond quote
Fair value valuation technique of redeemable noncontrolling interest	Discounted cash flows
Fair value unobservable input credit valuation adjustment of interest rate swap	Credit spread
Fair value unobservable input of total return swap	Discount rate
Fair Value Unobservable Input Total Return Swap	Capitalization rate
Fair value unobservable input adjustment to borrowings subject to total rate of return swap	Discount rate
Fair value unobservable input adjustment to borrowings subject total rate of return swap	Capitalization rate
Fair value unobservable input redeemable noncontrolling interest	Discount rate
Percentage of input values credit valuation adjustment of interest rate swap	4.25%
Percentage of input values redeemable noncontrolling interest	9.30%
Fair Value, Inputs, Level 3 [Member]
Fair value of financial instruments measured on a recurring basis
Credit valuation adjustment of interest rate swap	11,517,000
Fair value measurement of total return swap	(6,837,000)
Fair value adjustment to borrowings subject to total rate of return swap	10,044,000
Redeemable noncontrolling interest	$ (238,942,000)		$ (239,136,000)
Discount rate [Member]
Fair value of financial instruments measured on a recurring basis
Input Values Total Rate Of Return Swap	N/A	[1]
Input values of fair value adjustment to the borrowing subject total rate of return swap	N/A	[1]
Capitalization rate [Member]
Fair value of financial instruments measured on a recurring basis
Input Values Total Rate Of Return Swap	N/A	[1]
Input values of fair value adjustment to the borrowing subject total rate of return swap	N/A	[1]

[1] The Company does not have access to certain significant unobservable inputs used by these third parties to determine these fair values.