Derivative Instruments and Hedging Activities (Details) (USD $)	Oct. 31, 2013	Jan. 31, 2013
Other Assets [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivatives, Current Notional	$ 47,900,000	$ 28,000,000
Asset Derivatives, Fair Value	994,000	965,000
Other Assets [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivatives, Current Notional	590,868,000	638,762,000
Asset Derivatives, Fair Value	19,212,000	20,349,000
Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivatives, Current Notional	1,189,223,000	1,258,315,000
Liability Derivatives, Fair Value	114,425,000	140,437,000
Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivatives, Current Notional	39,066,000	39,562,000
Liability Derivatives, Fair Value	17,201,000	15,287,000
Interest rate caps [Member] | Other Assets [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivatives, Current Notional	0	0
Asset Derivatives, Fair Value	0	0
Interest rate caps [Member] | Other Assets [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivatives, Current Notional	450,068,000	479,085,000
Asset Derivatives, Fair Value	12,000	7,000
Interest rate caps [Member] | Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivatives, Current Notional	0	0
Liability Derivatives, Fair Value	0	0
Interest rate caps [Member] | Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivatives, Current Notional	0	0
Liability Derivatives, Fair Value	0	0
Interest rate swap agreements [Member] | Other Assets [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivatives, Current Notional	0	0
Asset Derivatives, Fair Value	0	0
Interest rate swap agreements [Member] | Other Assets [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivatives, Current Notional	0	18,877,000
Asset Derivatives, Fair Value	0	241,000
Interest rate swap agreements [Member] | Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivatives, Current Notional	961,438,000	1,019,920,000
Liability Derivatives, Fair Value	106,571,000	129,522,000
Interest rate swap agreements [Member] | Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivatives, Current Notional	0	0
Liability Derivatives, Fair Value	0	0
Total Return Swap [Member] | Other Assets [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivatives, Current Notional	47,900,000	28,000,000
Asset Derivatives, Fair Value	994,000	965,000
Total Return Swap [Member] | Other Assets [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivatives, Current Notional	140,800,000	140,800,000
Asset Derivatives, Fair Value	19,200,000	20,101,000
Total Return Swap [Member] | Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivatives, Current Notional	227,785,000	238,395,000
Liability Derivatives, Fair Value	7,854,000	10,915,000
Total Return Swap [Member] | Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivatives, Current Notional	39,066,000	39,562,000
Liability Derivatives, Fair Value	$ 17,201,000	$ 15,287,000