Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ (378,285)	$ (337,312)
Loss attributable to redeemable noncontrolling interest	4,308	1,879
Total realized and unrealized gains (losses):
Included in earnings	7,652	1,454
Included in other comprehensive income	1,463	(19,072)
Included in additional paid-in capital	(7,266)	(1,986)
Settlement		0
Ending Balance	(372,128)	(355,037)
Redeemable Noncontrolling Interest [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(229,149)	(226,829)
Loss attributable to redeemable noncontrolling interest	4,308	1,879
Total realized and unrealized gains (losses):
Included in earnings	0	0
Included in other comprehensive income	0	0
Included in additional paid-in capital	(7,266)	(1,986)
Settlement		0
Ending Balance	(232,107)	(226,936)
Interest Rate Swaps [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(143,303)	(102,387)
Loss attributable to redeemable noncontrolling interest	0	0
Total realized and unrealized gains (losses):
Included in earnings	0	0
Included in other comprehensive income	1,463	(19,072)
Included in additional paid-in capital	0	0
Settlement		0
Ending Balance	(141,840)	(121,459)
Net TRS [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(15,013)	(30,034)
Loss attributable to redeemable noncontrolling interest	0	0
Total realized and unrealized gains (losses):
Included in earnings	7,282	8,918
Included in other comprehensive income	0	0
Included in additional paid-in capital	0	0
Settlement		903
Ending Balance	(7,731)	(20,213)
Fair Value Adjustment to the Borrowings Subject to TRS [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	9,180	21,938
Loss attributable to redeemable noncontrolling interest	0	0
Total realized and unrealized gains (losses):
Included in earnings	370	(7,464)
Included in other comprehensive income	0	0
Included in additional paid-in capital	0	0
Settlement		(903)
Ending Balance	9,550	13,571
Total TRS Related [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(5,833)	(8,096)
Loss attributable to redeemable noncontrolling interest	0	0
Total realized and unrealized gains (losses):
Included in earnings	7,652	1,454
Included in other comprehensive income	0	0
Included in additional paid-in capital	0	0
Settlement		0
Ending Balance	$ 1,819	$ (6,642)