Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity (Impact Of Derivative Instruments On Statements Of Financial Performance And Financial Position) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Interest rate swap agreements in a gain position (an asset)	$ 617,000		$ 9,597,000
Related net interest payable	(10,023,000)	[1]	(9,847,000)	[1]
Interest rate swap agreements in a loss position (a liability)	(40,754,000)		(16,587,000)
Amount of gain (loss) reclassified from AOCI (effective portion)	(28,066,000)		(27,546,000)		(57,827,000)
Amount of gain (loss) recognized (ineffective portion)	(827,000)		(140,000)		(1,148,000)
Increase in interest expense and decrease in Net income as a result of the use of derivatives	(28,893,000)	[2]	(27,686,000)	[2]	(58,975,000)	[2]
Amount of loss recognized in other comprehensive income (loss) (effective portion)	(51,751,000)		(27,587,000)		(16,709,000)
Recognition period for recognizing unrealized losses on derivatives	twelve months
Derivative instruments unrealized losses to be recognized	6,600,000
Notional amount of swap agreement			100,000,000
Repurchase Arrangements And Similar Borrowings [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Interest rate swap agreements in a gain position (an asset)	617,000	[3]	734,000	[3]
Interest rate swap agreements at fair value - (a liability)	(15,691,000)	[3]	(16,337,000)	[3]
Unsecured Borrowings [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Interest rate swap agreements in a gain position (an asset)			8,863,000	[3]
Interest rate swap agreements at fair value - (a liability)	(15,657,000)	[3]
Effective Portion Of Active Positions [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Amount of gain (loss) reclassified from AOCI (effective portion)	(28,066,000)		(27,554,000)		(56,585,000)
Effective Portion Of Terminated Positions [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Amount of gain (loss) reclassified from AOCI (effective portion)			$ 8,000		$ (1,242,000)

[1] Included in "Accounts payable and accrued expenses" on the face of the balance sheet.

[2] Included in "Interest expense: Repurchase arrangements and similar borrowings" on the face of the statement of income.

[3] The fair value of derivatives with realized and unrealized gains are aggregated and recorded as an asset on the face of the balance sheet separately from the fair value of derivatives with realized and unrealized losses that are recorded as a liability. The amount of unrealized losses that will be recognized in the statement of income over the next twelve months in the form of fixed- and variable-rate swap payments in excess of current market rates totaled $6.6 million at December 31, 2011.