v3.26.1
Investments (Securities Pledged as Collateral Related to Repurchase Reverse Repurchase Program) (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral $ 792 $ 831
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 2,457 2,623
Obligation to Return Securities Received as Collateral 3,249 3,454
Corporate Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 416 428
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 1,297 1,336
Debt Security, Government, Non-US [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 21 21
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 112 107
Asset-backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 16 25
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 115 148
Commercial Mortgage Backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 30 37
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 225 276
Residential mortgage-backed securities    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 10 10
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 46 89
JAPAN    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 299 310
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 380 378
US Government Agencies Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 270 277
CANADA    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 12 12
Maturity Overnight [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Obligation to Return Securities Received as Collateral 0 0
Maturity Overnight [Member] | Corporate Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity Overnight [Member] | Debt Security, Government, Non-US [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity Overnight [Member] | Asset-backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity Overnight [Member] | Commercial Mortgage Backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity Overnight [Member] | Residential mortgage-backed securities    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity Overnight [Member] | JAPAN    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity Overnight [Member] | US Government Agencies Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity Overnight [Member] | CANADA    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 149 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Obligation to Return Securities Received as Collateral 149 0
Maturity up to 30 days [Member] | Corporate Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity up to 30 days [Member] | Debt Security, Government, Non-US [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity up to 30 days [Member] | Asset-backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity up to 30 days [Member] | Commercial Mortgage Backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity up to 30 days [Member] | Residential mortgage-backed securities    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity up to 30 days [Member] | JAPAN    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 149 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity up to 30 days [Member] | US Government Agencies Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity up to 30 days [Member] | CANADA    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity 30 to 90 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 275 444
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 199 309
Obligation to Return Securities Received as Collateral 474 753
Maturity 30 to 90 Days [Member] | Corporate Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 211 357
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 199 0
Maturity 30 to 90 Days [Member] | Debt Security, Government, Non-US [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 11 15
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity 30 to 90 Days [Member] | Asset-backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 13 25
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 11
Maturity 30 to 90 Days [Member] | Commercial Mortgage Backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 30 37
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 49
Maturity 30 to 90 Days [Member] | Residential mortgage-backed securities    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 10 10
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 42
Maturity 30 to 90 Days [Member] | JAPAN    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 203
Maturity 30 to 90 Days [Member] | US Government Agencies Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 4
Maturity 30 to 90 Days [Member] | CANADA    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 0
Maturity over 90 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 368 387
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 2,258 2,314
Obligation to Return Securities Received as Collateral 2,626 2,701
Maturity over 90 days [Member] | Corporate Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 205 71
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 1,098 1,336
Maturity over 90 days [Member] | Debt Security, Government, Non-US [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 10 6
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 112 107
Maturity over 90 days [Member] | Asset-backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 3 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 115 137
Maturity over 90 days [Member] | Commercial Mortgage Backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 225 227
Maturity over 90 days [Member] | Residential mortgage-backed securities    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 0 0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 46 47
Maturity over 90 days [Member] | JAPAN    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 150 310
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 380 175
Maturity over 90 days [Member] | US Government Agencies Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 270 273
Maturity over 90 days [Member] | CANADA    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement $ 12 $ 12