Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net Investment Income [Line Items]
Gross investment income	$ 87,366	$ 189,419	$ 264,757	$ 349,129
Investment expense	(1,935)	(1,086)	(4,563)	(2,542)
Net investment income	85,431	188,333	260,194	346,587
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	105,843	128,903	233,861	261,022
Investment funds
Net Investment Income [Line Items]
Gross investment income	(57,552)	46,840	(16,975)	58,251
Arbitrage trading account
Net Investment Income [Line Items]
Gross investment income	31,304	7,199	32,442	17,784
Real estate
Net Investment Income [Line Items]
Gross investment income	5,045	5,174	11,141	9,481
Equity securities
Net Investment Income [Line Items]
Gross investment income	$ 2,726	$ 1,303	$ 4,288	$ 2,591

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.9)
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.2)
-URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263

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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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(2))
-URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263

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+ References

No definition available.

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