INVESTMENTS - Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net Investment Income [Line Items]
Gross investment income	$ 479,252	$ 374,271	$ 503,172
Investment expenses	(24,951)	(24,670)	(24,600)
Net investment income	454,301	349,601	478,572
Fixed maturities, available for sale
Net Investment Income [Line Items]
Gross investment income	262,049	317,121	384,053
Other investments
Net Investment Income [Line Items]
Gross investment income	181,906	16,059	60,038
Equity securities
Net Investment Income [Line Items]
Gross investment income	12,752	9,328	10,434
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	17,427	15,432	14,712
Cash and cash equivalents
Net Investment Income [Line Items]
Gross investment income	4,454	13,582	26,882
Short-term investments
Net Investment Income [Line Items]
Gross investment income	$ 664	$ 2,749	$ 7,053

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.

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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)
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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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