Net Investment Income (Net Investment Income) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Investment Income [Line Items]
Gross investment income	$ 523,362	$ 610,530	$ 554,308
Investment expense	(10,717)	(9,645)	(10,017)
Net investment income	512,645	600,885	544,291
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	428,325	439,489	442,287
Equity securities available for sale
Net Investment Income [Line Items]
Gross investment income	4,624	6,726	11,380
Investment funds
Net Investment Income [Line Items]
Gross investment income	62,228	131,649	67,712
Arbitrage trading account
Net Investment Income [Line Items]
Gross investment income	16,891	22,438	20,431
Real estate
Net Investment Income [Line Items]
Gross investment income	$ 11,294	$ 10,228	$ 12,498

Amount before accretion (amortization) of purchase discount (premium) of interest income and dividend income on nonoperating securities.

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Amount of expenses related to the generation of investment income.

+ 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=26872669&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

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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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+ References

No definition available.

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