INVESTMENTS - Mortgage Loans (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, end of period	$ 81
Commercial Mortgage Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	33
Current-period provision for expected credit losses	44
Write-offs charged against the allowance	0
Recoveries of amounts previously written off	0
Net change in allowance	44
Balance, end of period	77
Agricultural Mortgage Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	3
Current-period provision for expected credit losses	1
Write-offs charged against the allowance	0
Recoveries of amounts previously written off	0
Net change in allowance	1
Balance, end of period	$ 4