Fair Value Measurements (Details) (Fair value measurement, recurring basis [Member], USD $) In Thousands, unless otherwise specified	Jan. 31, 2013	Jan. 31, 2012
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Fair value adjustment to the borrowings subject to TRS	$ 9,950	$ 9,180
Redeemable noncontrolling interest	(239,136)	(229,149)
Fair value of financial assets and liabilities and redeemable noncontrolling interests on a recurring basis	(363,596)	(382,585)
Interest rate caps [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	7	13
Interest rate swap agreements [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	241	1,083
Derivative Liabilities	(129,522)	(148,699)
Total Return Swap [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	21,066	10,308
Derivative Liabilities	(26,202)	(25,321)
Fair Value, Inputs, Level 1 [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Fair value adjustment to the borrowings subject to TRS	0	0
Redeemable noncontrolling interest	0	0
Fair value of financial assets and liabilities and redeemable noncontrolling interests on a recurring basis	0	0
Fair Value, Inputs, Level 1 [Member] | Interest rate caps [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Interest rate swap agreements [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	0	0
Derivative Liabilities	0	0
Fair Value, Inputs, Level 1 [Member] | Total Return Swap [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	0	0
Derivative Liabilities	0	0
Fair Value, Inputs, Level 2 [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Fair value adjustment to the borrowings subject to TRS	0	0
Redeemable noncontrolling interest	0	0
Fair value of financial assets and liabilities and redeemable noncontrolling interests on a recurring basis	(2,768)	(4,300)
Fair Value, Inputs, Level 2 [Member] | Interest rate caps [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	7	13
Fair Value, Inputs, Level 2 [Member] | Interest rate swap agreements [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	241	1,083
Derivative Liabilities	(3,016)	(5,396)
Fair Value, Inputs, Level 2 [Member] | Total Return Swap [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	0	0
Derivative Liabilities	0	0
Fair Value, Inputs, Level 3 [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Fair value adjustment to the borrowings subject to TRS	9,950	9,180
Redeemable noncontrolling interest	(239,136)	(229,149)
Fair value of financial assets and liabilities and redeemable noncontrolling interests on a recurring basis	(360,828)	(378,285)
Fair Value, Inputs, Level 3 [Member] | Interest rate caps [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Interest rate swap agreements [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	0	0
Derivative Liabilities	(126,506)	(143,303)
Fair Value, Inputs, Level 3 [Member] | Total Return Swap [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative Assets	21,066	10,308
Derivative Liabilities	$ (26,202)	$ (25,321)