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Investments (Net Investment Income) (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Statement [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net investment income earned | $ 30,108 | $ 32,061 | $ 32,230 | $ 26,917 | $ 32,108 | $ 34,292 | $ 36,774 | $ 35,534 | $ 121,316 | $ 138,708 | $ 134,643
Fixed Income Securities [Member] |  |  |  |  |  |  |  |  |  |  |
Statement [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net investment income earned |  |  |  |  |  |  |  |  | 123,230 | 126,489 | 121,582
Equity Securities, Dividend Income [Member] |  |  |  |  |  |  |  |  |  |  |
Statement [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net investment income earned |  |  |  |  |  |  |  |  | 9,161 | 7,449 | 6,140
Short-term Investments [Member] |  |  |  |  |  |  |  |  |  |  |
Statement [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net investment income earned |  |  |  |  |  |  |  |  | 112 | 66 | 117
Other Investment Portfolio [Member] |  |  |  |  |  |  |  |  |  |  |
Statement [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net investment income earned |  |  |  |  |  |  |  |  | (1,890) | 13,580 | 15,208
Investment Expenses [Member] |  |  |  |  |  |  |  |  |  |  |
Statement [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net investment income earned |  |  |  |  |  |  |  |  | $ (9,297) | $ (8,876) | $ (8,404)

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- Definition Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments. + References Reference 1: 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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 16 -Article 12 + Details
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