Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Oct. 31, 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	$ (337,312)
Total realized and unrealized gains (losses):
Included in earnings	2,727
Included in other comprehensive income	(31,745)
Included in additional paid-in capital	(4,808)
Ending Balance	(371,138)
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	(226,829)
Total realized and unrealized gains (losses):
Included in earnings	2,852
Included in additional paid-in capital	(4,808)
Ending Balance	(228,785)
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	(102,387)
Total realized and unrealized gains (losses):
Included in other comprehensive income	(31,745)
Ending Balance	(134,132)
Net Total Return Swap [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	(30,034)
Total realized and unrealized gains (losses):
Included in earnings	9,529
Settlement	903
Ending Balance	(19,602)
Fair value adjustment to the borrowing 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	21,938
Total realized and unrealized gains (losses):
Included in earnings	(9,654)
Settlement	(903)
Ending Balance	11,381
Total Return Swap 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	(8,096)
Total realized and unrealized gains (losses):
Included in earnings	(125)
Ending Balance	$ (8,221)