INVESTMENTS - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020		Dec. 31, 2019
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period			$ (180)
Balance, end of period	$ (139)		(139)
Transitional real estate loans
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	(47)	$ (27)	(63)	$ (22)	[1]
Cumulative Effect of Adoption of 2016-13						$ (2)
(Addition to) release of allowance for credit losses	6	(39)	22	(42)
Write-offs, net of recoveries		0	0	0
Balance, end of period	(41)	(66)	(41)	(66)
Commercial mortgage loans
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	(24)	(11)	(33)	(3)	[1]
Cumulative Effect of Adoption of 2016-13						(8)
(Addition to) release of allowance for credit losses	2	(31)	11	(31)
Write-offs, net of recoveries		0	0	0
Balance, end of period	(22)	(42)	(22)	(42)
Middle market loans
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	(83)	(87)	(85)	(20)	[1]
Cumulative Effect of Adoption of 2016-13						(33)
(Addition to) release of allowance for credit losses	7	(56)	9	(90)
Write-offs, net of recoveries		9	0	9
Balance, end of period	(76)	(134)	(76)	(134)
Held-to-maturity securities
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	(8)	(9)	(9)	0	[1]
Cumulative Effect of Adoption of 2016-13						(10)
(Addition to) release of allowance for credit losses	0	0	1	1
Write-offs, net of recoveries		0	0	0
Balance, end of period	(8)	(9)	(8)	(9)
Available-for-sale securities
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	(27)	(63)	(38)	0	[1]
Cumulative Effect of Adoption of 2016-13						0
(Addition to) release of allowance for credit losses	1	(11)	0	(74)
Write-offs, net of recoveries		36	12	36
Balance, end of period	(26)	(38)	(26)	(38)
Reinsurance recoverables
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	(13)	(11)	(11)	0	[1]
Cumulative Effect of Adoption of 2016-13						$ (11)
(Addition to) release of allowance for credit losses	0	0	(2)	0
Write-offs, net of recoveries		0	0	0
Balance, end of period	$ (13)	$ (11)	$ (13)	$ (11)

[1] U.S. GAAP guidance adopted as of January 1, 2020 has superseded these losses, included for comparative purposes only.