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Investments (Components of Net Realized and Unrealized Gains (Losses)) (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2018 | [1],[2] | Sep. 30, 2018 | [1] | Jun. 30, 2018 | [1] | Mar. 31, 2018 | [1] | Dec. 31, 2017 | [1],[2] | Sep. 30, 2017 | [1] | Jun. 30, 2017 | [1] | Mar. 31, 2017 | [1] | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |  |  |  |  |
Unrealized Gain (Loss) on Investments |  |  |  |  |  |  |  |  | $ (3,100) |  |
Unrealized Gain Loss on Equity Securities Sold |  |  |  |  |  |  |  |  | (26,300) |  |
Net realized investment (losses) gains on disposals |  |  |  |  |  |  |  |  | (18,975) | $ 11,204 | $ 3,562
OTTI charges |  |  |  |  |  |  |  |  | (6,579) | (4,845) | (8,499)
Net realized (losses) gains |  |  |  |  |  |  |  |  | (25,554) | 6,359 | (4,937)
Unrealized losses recognized in income on equity securities |  |  |  |  |  |  |  |  | (29,369) | 0 | 0
Total net realized and unrealized (losses) gains | $ (37,935) | $ (4,787) | $ (1,652) | $ (10,549) | $ (1,128) | $ 6,798 | $ 1,734 | $ (1,045) | (54,923) | 6,359 | (4,937)
Fixed Income Securities [Member] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net realized investment (losses) gains on disposals |  |  |  |  |  |  |  |  | (34,953) | 6,944 | (3,668)
Equity Securities [Member] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net realized investment (losses) gains on disposals |  |  |  |  |  |  |  |  | 18,695 | 4,629 | 7,244
Short-term Investments [Member] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net realized investment (losses) gains on disposals |  |  |  |  |  |  |  |  | (3) | (4) | (13)
Other Investments [Member] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net realized investment (losses) gains on disposals |  |  |  |  |  |  |  |  | $ (2,714) | $ (365) | $ (1)
[1] | Effective January 1, 2018, changes in unrealized gains and losses on our equity portfolio are recognized in income through "Net unrealized losses on equity securities" on our Consolidated Statements of Income, as a result of our adoption of ASU 2016-01. See Note 3. "Adoption of Accounting Pronouncements" above.
[2] | Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

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