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Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net Investment Income [Line Items]
Net investment income earned	$ 45,553	$ 41,430	$ 88,784	$ 78,849
Fixed Income Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	43,774	37,668	85,815	74,559
Equity Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	1,820	1,419	3,797	2,887
Short-Term Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	611	377	1,134	627
Other Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	2,094	5,231	3,657	6,834
Investment Expenses [Member]
Net Investment Income [Line Items]
Net investment income earned	$ (2,746)	$ (3,265)	$ (5,619)	$ (6,058)

X

- 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 FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-16(Column G))
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574960-122915

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- Definition

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+ References

No definition available.

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