INVESTMENT OPERATIONS - Summary of Net Realized Investment Gains (Losses) for All Other Investments (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Fixed maturities		$ 45,324	$ 47,711	$ 9,851
Equity securities		13,092	46,989	(49,275)
Modco trading portfolio		182,591	247,330	(185,900)
Net credit losses recognized in operations	$ (125,470)	(125,470)
Net impairment losses recognized in operations			(34,453)	(29,724)
Commercial mortgage loans		(151,994)	(2,263)	(2,040)
Other investments		(3,349)	3,231	4,088
Realized gains (losses) - investments		(39,806)	308,545	(253,000)
Realized gains (losses) - derivatives		8,679	(131,459)	79,097
Realized gains (losses)		$ (31,127)	$ 177,086	$ (173,903)

Realized Investment Gains (Losses), All Investments

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Represents the total realized gain (loss) included in earnings during the period as a result of investments other than derivative financial instruments, net of the amount recognized in earnings for other than temporary impairments (OTTI) of investments in debt and equity securities.

+ References

No definition available.

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- Definition

Amount of expense for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), for which no credit loss was previously recorded.

+ References

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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Amount of unrealized and realized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

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Amount of gain (loss) included in earnings for investments classified as other.

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Amount of realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI).

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Amount of other-than-temporary impairment (OTTI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), recognized in earnings and other comprehensive loss (OCI).

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