INVESTMENTS - Schedule of Allowance for Credit Losses for AFS Debt Securities (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period		$ 5
Less: Write-offs		0
Recoveries of amounts written-off		0
Net credit losses (NCLs)		0
Credit losses on securities without previous credit losses		0
Net reserve builds (releases) on securities with previous credit losses		0
Total provision for credit losses	[1]	0	$ 0
Initial allowance on newly purchased credit-deteriorated securities during the period		0
Allowance for credit losses at end of period		5	$ 0
Foreign government
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period		0
Less: Write-offs		0
Recoveries of amounts written-off		0
Net credit losses (NCLs)		0
Credit losses on securities without previous credit losses		0
Net reserve builds (releases) on securities with previous credit losses		0
Total provision for credit losses		0
Initial allowance on newly purchased credit-deteriorated securities during the period		0
Allowance for credit losses at end of period		0
Corporate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period		5
Less: Write-offs		0
Recoveries of amounts written-off		0
Net credit losses (NCLs)		0
Credit losses on securities without previous credit losses		0
Net reserve builds (releases) on securities with previous credit losses		0
Total provision for credit losses		0
Initial allowance on newly purchased credit-deteriorated securities during the period		0
Allowance for credit losses at end of period		$ 5

[1] In accordance with ASC 326.