Fair Value of Financial Instruments (Estimated Fair Values Of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Liabilities
Total return swap	$ 1,412	$ 4,025
Unsecured Debt	150,000us-gaap_UnsecuredDebt	150,000us-gaap_UnsecuredDebt
Investments [Member]
Assets
Investments	3,443,363	3,403,822
Secured Notes [Member]
Liabilities
Secured notes payable	140,000	140,000
Equity Contract [Member]
Liabilities
Equity contracts	$ 888	$ 194

Equity Contracts Financial Instruments Liabilities Fair Value Disclosure

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

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-Publisher FASB

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-Topic 825

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Fair value before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

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-Paragraph 7

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-Topic 815

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-Section 50

-Paragraph 4B

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-Glossary Available-for-Sale Securities

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-Glossary Trading Securities

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-Topic 320

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a, f, g

-Article 7

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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-Section 02

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-Subsection 19, 20, 22

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