Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ (378,285)	$ (337,312)
Transfers in	(2,125)
Contributions from redeemable noncontrolling interest	11,348	0	181,909
Loss attributable to redeemable noncontrolling interest	9,785	4,567
Total realized and unrealized gains (losses):
Included in earnings	12,568	2,263
Included In noncontrolling interest	204
Included in other comprehensive income	16,797	(40,916)
Included in additional paid-in capital	(8,424)	(6,887)
Settlement		0
Ending Balance	(360,828)	(378,285)	(337,312)
Redeemable Noncontrolling Interest [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(229,149)	(226,829)
Transfers in	0
Contributions from redeemable noncontrolling interest	11,348
Loss attributable to redeemable noncontrolling interest	9,785	4,567
Total realized and unrealized gains (losses):
Included in earnings	0	0
Included In noncontrolling interest	0
Included in other comprehensive income	0	0
Included in additional paid-in capital	(8,424)	(6,887)
Settlement		0
Ending Balance	(239,136)	(229,149)
Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(143,303)	(102,387)
Transfers in	0
Contributions from redeemable noncontrolling interest	0
Loss attributable to redeemable noncontrolling interest	0	0
Total realized and unrealized gains (losses):
Included in earnings	0	0
Included In noncontrolling interest	0
Included in other comprehensive income	16,797	(40,916)
Included in additional paid-in capital	0	0
Settlement		0
Ending Balance	(126,506)	(143,303)
Net TRS [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(15,013)	(30,034)
Transfers in	(2,125)
Contributions from redeemable noncontrolling interest	0
Loss attributable to redeemable noncontrolling interest	0	0
Total realized and unrealized gains (losses):
Included in earnings	11,798	14,118
Included In noncontrolling interest	204
Included in other comprehensive income	0	0
Included in additional paid-in capital	0	0
Settlement		903
Ending Balance	(5,136)	(15,013)
Fair Value Adjustment to the Borrowings Subject to TRS [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	9,180	21,938
Transfers in	0
Contributions from redeemable noncontrolling interest	0
Loss attributable to redeemable noncontrolling interest	0	0
Total realized and unrealized gains (losses):
Included in earnings	770	(11,855)
Included In noncontrolling interest	0
Included in other comprehensive income	0	0
Included in additional paid-in capital	0	0
Settlement		(903)
Ending Balance	9,950	9,180
TRS Related [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(5,833)	(8,096)
Transfers in	(2,125)
Contributions from redeemable noncontrolling interest	0
Loss attributable to redeemable noncontrolling interest	0	0
Total realized and unrealized gains (losses):
Included in earnings	12,568	2,263
Included In noncontrolling interest	204
Included in other comprehensive income	0	0
Included in additional paid-in capital	0	0
Settlement		0
Ending Balance	$ 4,814	$ (5,833)