Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 30, 2012	Apr. 30, 2011
Reconciliation of financial assets and liabilities and redeemable noncontrolling interest measured at fair value on a recurring basis using significant unobservable inputs
Beginning Balance	$ (378,285)	$ (337,312)
Loss attributable to redeemable noncontrolling interest	1,691	666
Included in earnings	4,303	1,040
Included in other comprehensive income	6,786	(1,750)
Included in additional paid-in capital	(2,980)	(619)
Ending Balance	(368,485)	(337,975)
Redeemable Noncontrolling Interest [Member]
Reconciliation of financial assets and liabilities and redeemable noncontrolling interest measured at fair value on a recurring basis using significant unobservable inputs
Beginning Balance	(229,149)	(226,829)
Loss attributable to redeemable noncontrolling interest	1,691	666
Included in additional paid-in capital	(2,980)	(619)
Ending Balance	(230,438)	(226,782)
Interest Rate Swaps [Member]
Reconciliation of financial assets and liabilities and redeemable noncontrolling interest measured at fair value on a recurring basis using significant unobservable inputs
Beginning Balance	(143,303)	(102,387)
Included in other comprehensive income	6,786	(1,750)
Ending Balance	(136,517)	(104,137)
Net TRS [Member]
Reconciliation of financial assets and liabilities and redeemable noncontrolling interest measured at fair value on a recurring basis using significant unobservable inputs
Beginning Balance	(15,013)	(30,034)
Included in earnings	4,158	2,522
Ending Balance	(10,855)	(27,512)
Fair Value Adjustment to the Borrowings Subject to TRS [Member]
Reconciliation of financial assets and liabilities and redeemable noncontrolling interest measured at fair value on a recurring basis using significant unobservable inputs
Beginning Balance	9,180	21,938
Included in earnings	145	(1,482)
Ending Balance	9,325	20,456
Total TRS Related [Member]
Reconciliation of financial assets and liabilities and redeemable noncontrolling interest measured at fair value on a recurring basis using significant unobservable inputs
Beginning Balance	(5,833)	(8,096)
Included in earnings	4,303	1,040
Ending Balance	$ (1,530)	$ (7,056)