INVESTMENTS - Allowance for Credit Losses for Fixed Maturity Securities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2022	Sep. 30, 2021	Sep. 30, 2021
Fixed maturities, available-for-sale:
Balance, beginning of period	$ 1	$ 0	$ 1
Additions to allowance for credit losses not previously recorded	0	2	3
Reductions for securities sold during the period	0	0	(1)
Additions on securities with previous allowance	0	0	(1)
Balance, end of period	1	2	2
U.S Treasury securities and obligations of U.S. government authorities and agencies
Fixed maturities, available-for-sale:
Balance, beginning of period	0	0	0
Additions to allowance for credit losses not previously recorded	0	0	0
Reductions for securities sold during the period	0	0	0
Additions on securities with previous allowance	0	0	0
Balance, end of period	0	0	0
Foreign government bonds
Fixed maturities, available-for-sale:
Balance, beginning of period	0	0	0
Additions to allowance for credit losses not previously recorded	0	0	0
Reductions for securities sold during the period	0	0	0
Additions on securities with previous allowance	0	0	0
Balance, end of period	0	0	0
U.S. and Foreign Corporate Securities
Fixed maturities, available-for-sale:
Balance, beginning of period	1	0	1
Additions to allowance for credit losses not previously recorded	0	2	3
Reductions for securities sold during the period	0	0	(1)
Additions on securities with previous allowance	0	0	(1)
Balance, end of period	1	2	2
Asset-backed securities
Fixed maturities, available-for-sale:
Balance, beginning of period	0	0	0
Additions to allowance for credit losses not previously recorded	0	0	0
Reductions for securities sold during the period	0	0	0
Additions on securities with previous allowance	0	0	0
Balance, end of period	0	0	0
Commercial mortgage-backed securities
Fixed maturities, available-for-sale:
Balance, beginning of period	0	0	0
Additions to allowance for credit losses not previously recorded	0	0	0
Reductions for securities sold during the period	0	0	0
Additions on securities with previous allowance	0	0	0
Balance, end of period	0	0	0
Residential mortgage-backed securities
Fixed maturities, available-for-sale:
Balance, beginning of period	0	0	0
Additions to allowance for credit losses not previously recorded	0	0	0
Reductions for securities sold during the period	0	0	0
Additions on securities with previous allowance	0	0	0
Balance, end of period	$ 0	$ 0	$ 0