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Fair Value of Financial Instruments (Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Thousands | Sep. 30, 2015 | Dec. 31, 2014
--- | --- | ---
Liabilities |  |
Total return swap | $ 6,059 | $ 4,025
Liabilities, Fair Value Disclosure, Recurring | 296,325 | 294,219
Level 2 [Member] |  |
Liabilities |  |
Liabilities, Fair Value Disclosure, Recurring | 296,059 | 294,025
Secured Debt [Member] | Borrowings [Member] |  |
Liabilities |  |
Liabilities, Fair Value Disclosure, Recurring | 140,000 | 140,000
Secured Debt [Member] | Borrowings [Member] | Level 2 [Member] |  |
Liabilities |  |
Liabilities, Fair Value Disclosure, Recurring | 140,000 |
Unsecured Debt [Member] | Borrowings [Member] |  |
Liabilities |  |
Liabilities, Fair Value Disclosure, Recurring | 150,000 | 150,000
Unsecured Debt [Member] | Borrowings [Member] | Level 2 [Member] |  |
Liabilities |  |
Liabilities, Fair Value Disclosure, Recurring | 150,000 | 150,000
Equity Contract [Member] |  |
Liabilities |  |
Equity contracts | 266 | 194
Investments [Member] |  |
Assets |  |
Investments | $ 3,348,386 | 3,403,822
Secured Debt [Member] | Secured Debt [Member] | Borrowings [Member] | Level 2 [Member] |  |
Liabilities |  |
Liabilities, Fair Value Disclosure, Recurring |  | $ 140,000

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