INVESTMENTS - Mortgage Loans (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance	$ (66)	$ (66)
Commercial Real Estate Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	(43)	(33)
Current-period provision for expected credit losses	(19)	(29)
Write-offs charged against the allowance	0	0
Recoveries of amounts previously written off	0	0
Net change in allowance	(19)	(29)
Ending balance	(62)	(62)
Agricultural Real Estate Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	(3)	(3)
Current-period provision for expected credit losses	(1)	(1)
Write-offs charged against the allowance	0	0
Recoveries of amounts previously written off	0	0
Net change in allowance	(1)	(1)
Ending balance	$ (4)	$ (4)