INVESTMENTS - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) investment	Sep. 30, 2024 USD ($) investment	Jun. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Schedule of Investments [Line Items]
Held to maturity securities transferred to available for sale securities, number of investments | investment			0	0
Real estate owned impairments	$ 0	$ 0	$ 6	$ 0
Real estate owned, estimated fair value after impairment	12		12
Equity securities, FV-NI, unrealized gain (loss)	11	34	46	79
Transitional real estate loan commitments	165		165
Middle market loan commitments	732		732
Other loan commitments	1		1
Nonaccrual loans, interest income	0	0	1	0
Financing Receivable, Modified, Commitment to Lend	14		14			$ 14
Amortized Cost	16,960		16,960			15,971
Allowance for credit losses	422		422			355
Real estate owned, accumulated depreciation	35		35			14
Limited partnerships investment commitments	$ 3,100		$ 3,100			2,800
Percentage that the lending policy requires that the fair value of the securities received as collateral be of the fair value of the loaned securities	102.00%		102.00%
Percentage that the lending policy requires that the fair value of the unrestricted cash received as collateral be of the fair value of the loaned securities	100.00%		100.00%
Securities Lending, Securities Received as Collateral	$ 1,600		$ 1,600			3,000
Repurchase Agreements and Repurchase-to-Maturity Transactions Outstanding	0		0			0
Variable Interest Entity, Not Consolidated
Schedule of Investments [Line Items]
Limited partnerships investment commitments	2,000		2,000			2,100
Real estate owned
Schedule of Investments [Line Items]
Depreciation	8	4	21	8
Transitional real estate loans
Schedule of Investments [Line Items]
Nonaccrual loans, no allowance	45		45			140
Allowance for credit losses	271	151	271	151	$ 243	199	$ 123	$ 112
Transitional real estate loans | Potential Foreclosure or Deed-in-lieu Foreclosure
Schedule of Investments [Line Items]
Mortgage Loans in Process of Foreclosure, Amount	136		136
Allowance for credit losses	42		42
Middle market loans
Schedule of Investments [Line Items]
Nonaccrual loans, no allowance	21		21			5
Allowance for credit losses	139	$ 103	139	$ 103	$ 127	$ 140	$ 98	$ 146
Zero-credit-loss expectation | Japan government and agencies
Schedule of Investments [Line Items]
Amortized Cost	$ 16,100		$ 16,100
CALIFORNIA | Geographic Concentration Risk | Mortgages
Schedule of Investments [Line Items]
Concentration Risk, Percentage			22.00%
TEXAS | Geographic Concentration Risk | Mortgages
Schedule of Investments [Line Items]
Concentration Risk, Percentage			13.00%
FLORIDA | Geographic Concentration Risk | Mortgages
Schedule of Investments [Line Items]
Concentration Risk, Percentage			8.00%