Repurchase Arrangements And Similar Borrowings, Including Related Hedging Activity (Impact Of Derivative Instruments On Statements Of Financial Performance And Financial Position) (Details) (USD $)	1 Months Ended	3 Months Ended				9 Months Ended
	Mar. 31, 2008	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010		Dec. 31, 2010
Repurchase Arrangements And Similar Borrowings, Including Related Hedging Activity [Line Items]
Interest rate swap agreements in a gain position (an asset)		$ 338,000				$ 338,000				$ 9,597,000
Interest rate swap agreements at fair value - (a liability)		(36,704,000)	[1]			(36,704,000)	[1]			(16,337,000)	[1]
Related net interest payable		(9,575,000)	[2]			(9,575,000)	[2]			(9,847,000)	[2]
Interest rate swap agreements in a loss position (a liability)		(45,941,000)				(45,941,000)				(16,587,000)
Amount of loss reclassified from AOCI (effective portion)		(8,060,000)		(5,810,000)		(21,639,000)		(21,588,000)
Amount of gain (loss) recognized (ineffective portion)		(830,000)		(213,000)		(879,000)		36,000
Increase in interest expense and decrease in Net income as a result of the use of derivatives		(8,890,000)	[3]	(6,023,000)	[3]	(22,518,000)	[3]	(21,552,000)	[3]
Amount of loss recognized in other comprehensive income (loss) (effective portion)		(33,129,000)		(12,341,000)		(50,690,000)		(37,564,000)
Recognition period for recognizing unrealized losses on derivatives						twelve months
Derivative instruments unrealized losses to be recognized						15,400,000
Notional amount of swap agreement	100,000,000
Realized losses from terminated swap agreement	2,300,000
Amortization period of realized losses from terminated swap agreement	two-year
Effective Portion Of Active Positions [Member]
Repurchase Arrangements And Similar Borrowings, Including Related Hedging Activity [Line Items]
Amount of loss reclassified from AOCI (effective portion)		(8,060,000)		(5,810,000)		(21,639,000)		(21,557,000)
Effective Portion Of Terminated Positions [Member]
Repurchase Arrangements And Similar Borrowings, Including Related Hedging Activity [Line Items]
Amount of loss reclassified from AOCI (effective portion)								(31,000)	[4]
Repurchase Arrangements And Similar Borrowings [Member]
Repurchase Arrangements And Similar Borrowings, Including Related Hedging Activity [Line Items]
Interest rate swap agreements in a gain position (an asset)		338,000	[1]			338,000	[1]			734,000	[1]
Unsecured Borrowings [Member]
Repurchase Arrangements And Similar Borrowings, Including Related Hedging Activity [Line Items]
Interest rate swap agreements in a gain position (an asset)										$ 8,863,000	[1]

[1] 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 $15.4 million at September 30, 2011.

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

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

[4] In March 2008 a swap agreement with a $100 million notional amount was terminated for a realized loss of $2.3 million which was amortized to earnings over the original two-year term of the derivative (through January 2010).