INVESTMENTS - Securities Lending Transactions Accounted for as Secured Borrowings (Details) - USD ($) $ in Millions		Sep. 30, 2022	Dec. 31, 2021
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		$ 2,721	$ 2,162
Gross amount of recognized liabilities for securities lending		2,721	2,162
Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		1,874	920
Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		23	40
Sovereign and supranational
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	2
Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		96	88
Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		727	1,112
Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		1	0
Maturity Overnight and Continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	847	1,242
Maturity Overnight and Continuous | Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	0	0
Maturity Overnight and Continuous | Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	23	40
Maturity Overnight and Continuous | Sovereign and supranational
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	0	2
Maturity Overnight and Continuous | Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	96	88
Maturity Overnight and Continuous | Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	727	1,112
Maturity Overnight and Continuous | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	1	0
Maturity up to 30 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		1,874	920
Maturity up to 30 Days | Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		1,874	920
Maturity up to 30 Days | Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity up to 30 Days | Sovereign and supranational
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity up to 30 Days | Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity up to 30 Days | Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity up to 30 Days | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		$ 0	$ 0

[1] The related loaned security, under the Company's U.S. securities lending program, can be returned to the Company at the transferee's discretion; therefore, they are classified as Overnight and Continuous.