INVESTMENTS (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net Investment Income [Line Items]
Gross investment income	$ 110,796	$ 51,560	$ 231,253	$ 151,988
Investment expenses	(6,124)	(6,520)	(12,417)	(13,848)
Net investment income	104,672	45,040	218,836	138,140
Fixed maturities, available for sale
Net Investment Income [Line Items]
Gross investment income	61,244	80,459	130,714	170,402
Other investments
Net Investment Income [Line Items]
Gross investment income	41,414	(37,580)	83,248	(39,700)
Equity securities
Net Investment Income [Line Items]
Gross investment income	3,100	2,263	5,598	4,387
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	4,355	3,660	8,541	7,713
Cash and cash equivalents
Net Investment Income [Line Items]
Gross investment income	617	2,392	2,953	7,323
Short-term investments
Net Investment Income [Line Items]
Gross investment income	$ 66	$ 366	$ 199	$ 1,863

The net gain or loss (both realized and unrealized) related to investments in certain entities that calculate net asset value per share and the amount after accretion (amortization) of discount (premium), of interest income and dividend income on nonoperating securities.

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The net gain or loss (both realized and unrealized) related to investments in certain entities that calculate net asset value per share and the amount after accretion (amortization) of discount (premium) of interest income and dividend income on nonoperating securities, net of investment expense.

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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)
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

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-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=120400993&loc=SL114874131-224263

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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