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Investments (Tables) | 12 Months Ended
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Dec. 31, 2017
Investments [Abstract] |
Gains And Losses Due To Changes In Fair Value | The following table presents gains (losses) due to changes in fair value of investments that are measured at fair value pursuant to application of the fair value option:
| Year Ended December 31,
| 2017 |  | 2016 |  | 2015
| (Amounts in thousands)
Fixed maturity securities | $ | 50,403 |  |  | $ | (56,584 | ) |  | $ | (39,304 | )
Equity securities | 37,486 |  |  | 23,722 |  |  | (22,988 | )
Short-term investments | 38 |  |  | 57 |  |  | 561 |
Total gains (losses) | $ | 87,927 |  |  | $ | (32,805 | ) |  | $ | (61,731 | )
Gross Gains And Losses Realized On Sales Of Investments | ross gains (losses) realized on the sales of investments:
| Year Ended December 31,
| 2017 |  | 2016 |  | 2015
| (Amounts in thousands)
| Gross Realized Gains |  | Gross Realized Losses |  | Net |  | Gross Realized Gains |  | Gross Realized Losses |  | Net |  | Gross Realized Gains |  | Gross Realized Losses |  | Net
Fixed maturity securities | $ | 604 |  |  | $ | (2,701 | ) |  | $ | (2,097 | ) |  | $ | 3,327 |  |  | $ | (19,133 | ) |  | $ | (15,806 | ) |  | $ | 631 |  |  | $ | (495 | ) |  | $ | 136 |
Equity securities | 20,835 |  |  | (23,048 | ) |  | (2,213 | ) |  | 29,446 |  |  | (29,945 | ) |  | (499 | ) |  | 41,305 |  |  | (58,764 | ) |  | (17,459 | )
Short-term investments | 21 |  |  | (20 | ) |  | 1 |  |  | 6 |  |  | (530 | ) |  | (524 | ) |  | — |  |  | (1,396 | ) |  | (1,396 | )
Estimated Fair Values Of Investments | The following table presents the estimated fair values of the Company's fixed maturity securities at December 31, 2017 by contractual maturity. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.
| Estimated Fair Value
| (Amounts in thousands)
Fixed maturity securities: |
Due in one year or less | $ | 200,963 |
Due after one year through five years | 532,344 |
Due after five years through ten years | 286,031 |
Due after ten years | 1,873,439 |
Total | $ | 2,892,777 |
Investment Income | The following table presents a summary of net investment income:
| Year Ended December 31,
| 2017 |  | 2016 |  | 2015
| (Amounts in thousands)
Fixed maturity securities | $ | 102,790 |  |  | $ | 104,111 |  |  | $ | 108,122 |
Equity securities | 18,554 |  |  | 14,629 |  |  | 14,630 |
Short-term investments | 8,753 |  |  | 8,936 |  |  | 9,033 |
Total investment income | $ | 130,097 |  |  | $ | 127,676 |  |  | $ | 131,785 |
Less: investment expense | (5,167 | ) |  | (5,805 | ) |  | (5,486 | )
Net investment income | $ | 124,930 |  |  | $ | 121,871 |  |  | $ | 126,299 |

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- Definition Tabular disclosure of the realized and unrealized gains and losses reported in the statement of income which have resulted from the sale and holding of marketable securities, respectively, as well as the sale or disposal of cost method investments. Such amounts would include realized gains and losses on the sale or disposal of trading, available-for-sale, and held-to-maturity securities, unrealized gains and losses on trading securities, unrealized gains and losses on available-for-sale and held-to-maturity securities transferred to the trading securities category, realized gains and losses on the sale or disposal of cost method investments, and losses recognized for other than temporary impairments (OTTI) of such investments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27405-111563 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 5.M) -URI http://asc.fasb.org/extlink&oid=65877573&loc=d3e87990-122713 + Details
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- Definition Tabular disclosure of investment income, including, but not limited to, interest and dividend income and amortization of discount (premium) derived from debt and equity securities. Excludes realized and unrealized gain (loss) on investments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.9) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.2) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(a),(b)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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