Fair Value Of Financial Instruments (Estimated Fair Values Of Financial Instruments) (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Equity contracts	$ 2,049	$ 2,776
Investments [Member]
Investments, fair value	3,117,602	3,155,257
Interest Rate Swap Agreements [Member]
Financial instruments at fair value, assets	902	4,240
Interest rate swap agreements	2,010	3,042
Secured Notes [Member]
Notes	137,804	138,332
Unsecured Note [Member]
Notes	$ 125,764	$ 128,280

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

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Derivative instrument obligations meeting the definition of a liability which the Company is a party to as of the balance sheet date.

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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