INVESTMENTS - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Net Investment Income [Line Items]
Gross investment income (loss)	$ 956	$ 961	$ 1,976	$ 1,898
Investment expenses	(90)	(76)	(176)	(155)
Net investment income (loss)	866	885	1,800	1,743
Excluding Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	599	636	1,245	1,573
Investment expenses	(58)	(46)	(110)	(125)
Net investment income (loss)	541	590	1,135	1,448
Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	357	325	731	325
Investment expenses	(32)	(30)	(66)	(30)
Net investment income (loss)	325	295	665	295
Fixed maturities
Net Investment Income [Line Items]
Gross investment income (loss)	641	688	1,304	1,359
Fixed maturities | Excluding Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	386	416	777	1,087
Fixed maturities | Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	255	272	527	272
Mortgage loans on real estate
Net Investment Income [Line Items]
Gross investment income (loss)	228	198	456	375
Mortgage loans on real estate | Excluding Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	145	111	287	288
Mortgage loans on real estate | Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	83	87	169	87
Policy loans
Net Investment Income [Line Items]
Gross investment income (loss)	50	49	101	97
Policy loans | Excluding Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	46	49	94	97
Policy loans | Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	4	0	7	0
Other equity investments
Net Investment Income [Line Items]
Gross investment income (loss)	45	14	108	35
Other equity investments | Excluding Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	41	49	96	70
Other equity investments | Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	4	(35)	12	(35)
Trading securities
Net Investment Income [Line Items]
Gross investment income (loss)	4	5	20	19
Trading securities | Excluding Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	4	5	20	19
Trading securities | Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	0	0	0	0
Other investment income
Net Investment Income [Line Items]
Gross investment income (loss)	(12)	7	(13)	13
Other investment income | Excluding Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	(23)	6	(29)	12
Other investment income | Funds Withheld and NI Modco
Net Investment Income [Line Items]
Gross investment income (loss)	$ 11	$ 1	$ 16	$ 1