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Fair Value Measurement (Quantitative Information Regarding Level 3 Valuations) (Details) - Level 3 - USD ($) $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 30, 2018 | Dec. 31, 2017
Corporate debt, limited observable inputs |  |
Assets: |  |
Fair Value at | $ 8,380 | $ 13,703
Corporate debt, limited observable inputs | Market Comparable Securities | Minimum |  |
Assets: |  |
Comparability Adjustment | 0.00% |
Corporate debt, limited observable inputs | Market Comparable Securities | Maximum |  |
Assets: |  |
Comparability Adjustment | 5.00% |
Corporate debt, limited observable inputs | Market Comparable Securities | Weighted Average |  |
Assets: |  |
Comparability Adjustment | 2.50% |
Corporate debt, limited observable inputs | Discounted Cash Flows | Minimum |  |
Assets: |  |
Comparability Adjustment | 0.00% |
Corporate debt, limited observable inputs | Discounted Cash Flows | Maximum |  |
Assets: |  |
Comparability Adjustment | 5.00% |
Corporate debt, limited observable inputs | Discounted Cash Flows | Weighted Average |  |
Assets: |  |
Comparability Adjustment | 2.50% |
Residential mortgage-backed and other asset-backed securities |  |
Assets: |  |
Fair Value at | $ 9,420 | 4,986
Residential mortgage-backed and other asset-backed securities | Market Comparable Securities | Minimum |  |
Assets: |  |
Comparability Adjustment | 0.00% |
Residential mortgage-backed and other asset-backed securities | Market Comparable Securities | Maximum |  |
Assets: |  |
Comparability Adjustment | 5.00% |
Residential mortgage-backed and other asset-backed securities | Market Comparable Securities | Weighted Average |  |
Assets: |  |
Comparability Adjustment | 2.50% |
Residential mortgage-backed and other asset-backed securities | Discounted Cash Flows | Minimum |  |
Assets: |  |
Comparability Adjustment | 0.00% |
Residential mortgage-backed and other asset-backed securities | Discounted Cash Flows | Maximum |  |
Assets: |  |
Comparability Adjustment | 5.00% |
Residential mortgage-backed and other asset-backed securities | Discounted Cash Flows | Weighted Average |  |
Assets: |  |
Comparability Adjustment | 2.50% |
Other investments |  |
Assets: |  |
Fair Value at | $ 5 | $ 409
Other investments | Discounted Cash Flows | Minimum |  |
Assets: |  |
Comparability Adjustment | 0.00% |
Other investments | Discounted Cash Flows | Maximum |  |
Assets: |  |
Comparability Adjustment | 10.00% |
Other investments | Discounted Cash Flows | Weighted Average |  |
Assets: |  |
Comparability Adjustment | 5.00% |

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- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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