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Basis of Presentation and Significant Accounting Policies FX gain (loss) (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2019 | Mar. 31, 2018
Foreign Currency Transaction Gain (Loss), before Tax | $ 1,960 | $ 5,014
Loss and Loss Reserves [Member] |  |
Foreign Currency Transaction Gain (Loss), before Tax | 5,583 | 11,012
Gain (Loss) on Investments [Member] |  |
Foreign Currency Transaction Gain (Loss), before Tax | $ (2,698) | $ (4,804)

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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://fasb.org/us-gaap/role/ref/legacyRef -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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30700-110894 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30690-110894 + Details
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