INVESTMENTS - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	[1]	$ (45)
Allowance for Loan and Lease Losses, Period Increase (Decrease)	[2]	0	$ 18		$ 19
Balance, end of period		(180)	(45)	[1]
Transitional real estate loans
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	[3]	(22)
Transition impact to retained earnings			(2)
Allowance for Loan and Lease Losses, Period Increase (Decrease)		(39)
Write-offs, net of recoveries		0
Balance, end of period		(63)	(22)	[3]
Commercial mortgage loans
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	[3]	(3)
Transition impact to retained earnings			(8)
Allowance for Loan and Lease Losses, Period Increase (Decrease)		(21)
Write-offs, net of recoveries		0
Balance, end of period		(32)	(3)	[3]
Middle market loans
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	[3]	(20)
Transition impact to retained earnings			(33)
Allowance for Loan and Lease Losses, Period Increase (Decrease)		(41)
Write-offs, net of recoveries		9
Balance, end of period		(85)	(20)	[3]
Held-to-maturity securities
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	[3]	0
Transition impact to retained earnings			(10)
Allowance for Loan and Lease Losses, Period Increase (Decrease)		0
Write-offs, net of recoveries		0
Balance, end of period		(10)	0	[3]
Available-for-sale securities
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	[3]	0
Transition impact to retained earnings			0
Allowance for Loan and Lease Losses, Period Increase (Decrease)		(75)
Write-offs, net of recoveries		37
Balance, end of period		(38)	0	[3]
Reinsurance recoverables
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	[3]	0
Transition impact to retained earnings			(11)
Allowance for Loan and Lease Losses, Period Increase (Decrease)		(1)
Write-offs, net of recoveries		0
Balance, end of period		$ (12)	$ 0	[3]

[1] U.S. GAAP guidance adopted as of January 1, 2020 has superseded these losses, included for comparative purposes only.

[2] U.S. GAAP guidance adopted as of January 1, 2020 has superseded these losses, included for comparative purposes only

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