v3.26.1
INVESTMENTS - Securities Lending Transactions Accounted for as Secured Borrowings (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions $ 6,414 $ 3,989
Gross amount of recognized liabilities for securities lending 6,414 3,989
Japan government and agencies    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 5,060 2,920
Public utilities    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 61 54
Banks/financial institutions    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 257 150
Other corporate    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 1,036 865
Maturity Overnight and Continuous    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions [1] 1,354 1,069
Maturity Overnight and Continuous | Japan government and agencies    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions [1] 0 0
Maturity Overnight and Continuous | Public utilities    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions [1] 61 54
Maturity Overnight and Continuous | Banks/financial institutions    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions [1] 257 150
Maturity Overnight and Continuous | Other corporate    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions [1] 1,036 865
Maturity up to 30 Days    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 2,250 1,591
Maturity up to 30 Days | Japan government and agencies    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 2,250 1,591
Maturity up to 30 Days | Public utilities    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 0 0
Maturity up to 30 Days | Banks/financial institutions    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 0 0
Maturity up to 30 Days | Other corporate    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 0 0
Maturity 30 to 90 Days    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 2,810 1,329
Maturity 30 to 90 Days | Japan government and agencies    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 2,810 1,329
Maturity 30 to 90 Days | Public utilities    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 0 0
Maturity 30 to 90 Days | Banks/financial institutions    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions 0 0
Maturity 30 to 90 Days | Other corporate    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Securities lending transactions $ 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.