Derivative Instruments and Hedging Activities (Details) (USD $)	Dec. 31, 2013	Jan. 31, 2013
Other Assets [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivative, Current Notional	$ 18,970,000	$ 28,000,000
Asset Derivative, Fair Value	903,000	965,000
Other Assets [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivative, Current Notional	447,532,000	638,762,000
Asset Derivative, Fair Value	155,000	20,349,000
Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivative, Current Notional	1,301,144,000	1,258,315,000
Liability Derivative, Fair Value	107,630,000	140,437,000
Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivative, Current Notional	39,052,000	39,562,000
Liability Derivative, Fair Value	15,477,000	15,287,000
Interest rate caps [Member] | Other Assets [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivative, Current Notional	447,532,000	479,085,000
Asset Derivative, Fair Value	155,000	7,000
Interest rate caps [Member] | Accounts Payable, Accrued Expenses and Other Liabilities [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Liability Derivative, Current Notional	0	0
Liability Derivative, Fair Value	0	0
Interest rate swap agreements [Member] | Other Assets [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivative, Current Notional	0	0
Asset Derivative, Fair Value	0	0
Interest rate swap agreements [Member] | Other Assets [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivative, Current Notional		18,877,000
Asset Derivative, Fair Value		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 Derivative, Current Notional	961,359,000	1,019,920,000
Liability Derivative, Fair Value	97,858,000	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 Derivative, Current Notional		0
Liability Derivative, Fair Value		0
Total Return Swap [Member] | Other Assets [Member] | Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivative, Current Notional	18,970,000	28,000,000
Asset Derivative, Fair Value	903,000	965,000
Total Return Swap [Member] | Other Assets [Member] | Not Designated as Hedging Instrument [Member]
Fair Value of Derivative Instruments
Asset Derivative, Current Notional	0	140,800,000
Asset Derivative, Fair Value	0	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 Derivative, Current Notional	339,785,000	238,395,000
Liability Derivative, Fair Value	9,772,000	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 Derivative, Current Notional	39,052,000	39,562,000
Liability Derivative, Fair Value	$ 15,477,000	$ 15,287,000