Summary Of Significant Accounting Policies (Estimated Fair Value Of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Investments	$ 2,445,589
Equity contracts	655	2,776
Financial instrument, fair value	140,000	267,210
Investments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Investments	3,062,421	3,155,257
Interest Rate Swaps Agreements [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Interest rate swap agreements, assets	0	4,240
Interest rate swap agreements, liabilities	670	3,042
Secured Notes [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instrument, fair value	140,000	138,332
Unsecured Note [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instrument, fair value	$ 0	$ 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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