INVESTMENTS - Schedule of Allowance for Credit Losses for AFS Debt Securities (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of year		$ 0
Less: Write-offs		0
Recoveries of amounts written-off		2
Net credit losses (NCLs)		2
Net reserve builds on securities that did not have previous reserves		8
Net reserve builds (releases) on securities that had previous reserves		(3)
Total provision for credit losses	[1]	3	$ 0	$ 0
Initial allowance on newly purchased credit-deteriorated securities during the year		0
Allowance for credit losses at end of year		5	0
Foreign government
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of year		0
Less: Write-offs		0
Recoveries of amounts written-off		0
Net credit losses (NCLs)		0
Net reserve builds on securities that did not have previous reserves		3
Net reserve builds (releases) on securities that had previous reserves		(3)
Total provision for credit losses		0
Initial allowance on newly purchased credit-deteriorated securities during the year		0
Allowance for credit losses at end of year		0	0
Corporate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of year		0
Less: Write-offs		0
Recoveries of amounts written-off		2
Net credit losses (NCLs)		2
Net reserve builds on securities that did not have previous reserves		5
Net reserve builds (releases) on securities that had previous reserves		0
Total provision for credit losses		3
Initial allowance on newly purchased credit-deteriorated securities during the year		0
Allowance for credit losses at end of year		$ 5	$ 0

[1] In accordance with ASC 326.