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Investments (Components Of Net Realized Gains, Excluding OTTI Charges) (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |  |  |  |  |  |  |  |  |  |
HTM fixed income securities gains |  |  |  |  |  |  |  |  | $ 44 | $ 3 | $ 5
HTM fixed income securities losses |  |  |  |  |  |  |  |  | (1) | (1) | (1)
Short Term Investments Realized Gains |  |  |  |  |  |  |  |  | (2) | 0 | 0
Short Term Investments Realized Losses |  |  |  |  |  |  |  |  | (6) | (13) | 0
Other investment securities gains |  |  |  |  |  |  |  |  | 494 | 3 | 162
Other investment securities losses |  |  |  |  |  |  |  |  | (859) | (4) | (653)
Net realized investment gains | $ (1,128) | $ 6,798 | $ 1,734 | $ (1,045) | $ (7,686) | $ 3,688 | $ 1,765 | $ (2,704) | 11,204 | 3,562 | 31,537
Proceeds from sale of available-for-sale securities |  |  |  |  |  |  |  |  | 1,235,900 | 1,046,100 | 234,100
Fixed Income Securities [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |  |  |  |  |  |  |  |  |  |
AFS securities gains |  |  |  |  |  |  |  |  | 10,193 | 7,741 | 4,515
AFS securities losses |  |  |  |  |  |  |  |  | (3,292) | (11,411) | (312)
Equity Securities [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |  |  |  |  |  |  |  |  |  |
AFS securities gains |  |  |  |  |  |  |  |  | 5,829 | 8,108 | 29,168
AFS securities losses |  |  |  |  |  |  |  |  | $ (1,200) | $ (864) | $ (1,347)

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