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Basis of Presentation and Significant Accounting Policies FX gain (loss) (Details) - USD ($) $ in Thousands | 9 Months Ended
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Sep. 30, 2016 | Sep. 30, 2015
Loss and Loss Reserves [Member] |  |
Foreign Currency Transaction Gain (Loss), before Tax | $ (56,910) | $ (13,347)
Cash Equivalents [Member] |  |
Foreign Currency Transaction Gain (Loss), before Tax | 457 | 1,140
Gain (Loss) on Investments [Member] |  |
Foreign Currency Transaction Gain (Loss), before Tax | 22,030 | 3,801
Premiums Receivable [Member] |  |
Foreign Currency Transaction Gain (Loss), before Tax | 8,264 | (3,234)
Unrealized Gains Or (Losses) On Credit Derivative Contracts [Member] |  |
Foreign Currency Transaction Gain (Loss), before Tax | $ (929) | $ 4,895

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- Definition Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6450189&loc=d3e30700-110894 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450189&loc=d3e30690-110894 + Details
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