v3.26.1
Investments (Securities Pledged as Collateral Related to Repurchase Reverse Repurchase Program) (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral $ 699 $ 831
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 2,406 2,623
Obligation to Return Securities Received as Collateral 3,105 3,454
Corporate Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 360 428
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 1,326 1,336
Debt Security, Government, Non-US [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 15 21
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 91 107
Canadian and Canadian provincial governments    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 12 12
Asset-backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 7 25
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 83 148
Commercial Mortgage Backed Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 16 37
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 222 276
Residential mortgage-backed securities    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 6 10
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 45 89
JAPAN    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 295 310
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 360 378
US Government Agencies Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 267 277
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] | Canadian and Canadian provincial governments    
Assets Sold under Agreements to Repurchase [Line Items]    
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 up to 30 days [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 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] | Canadian and Canadian provincial governments    
Assets Sold under Agreements to Repurchase [Line Items]    
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 0 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 30 to 90 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 262 444
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 211 309
Obligation to Return Securities Received as Collateral 473 753
Maturity 30 to 90 Days [Member] | Corporate Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 225 357
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 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] | Canadian and Canadian provincial governments    
Assets Sold under Agreements to Repurchase [Line Items]    
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 4 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 16 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 6 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 211 203
Maturity 30 to 90 Days [Member] | US Government Agencies Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 0 4
Maturity over 90 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 437 387
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 2,195 2,314
Obligation to Return Securities Received as Collateral 2,632 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 135 71
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 1,326 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 4 6
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 91 107
Maturity over 90 days [Member] | Canadian and Canadian provincial governments    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 12 12
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 83 137
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 222 227
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 45 47
Maturity over 90 days [Member] | JAPAN    
Assets Sold under Agreements to Repurchase [Line Items]    
Securities Loaned, Fair Value of Collateral 295 310
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement 149 175
Maturity over 90 days [Member] | US Government Agencies Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement $ 267 $ 273