v3.26.3
Derivative Instruments - Summary of Notional and Fair Value of Derivative Assets and Liabilities (Details)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
Sep. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Derivative [Line Items]          
Derivative assets, fair value $ 10,950   $ 10,950   $ 9,190
Derivative liabilities, fair value 6,757   6,757   5,742
Total derivative liabilities 23,038   23,038   20,641
Derivative Asset, Including Embedded Derivatives 7,617   7,617   6,425
Derivatives designated as hedges          
Derivative [Line Items]          
Derivative assets, fair value 659   659   856
Derivative liabilities, fair value $ 1,182   $ 1,182   $ 1,174
Derivatives designated as hedges | Foreign currency swaps          
Derivative [Line Items]          
Notional Amount 29,398   29,398   26,437
Derivative assets, fair value $ 534   $ 534   $ 560
Derivative liabilities, fair value $ 501   $ 501   $ 868
Derivatives designated as hedges | Interest rate swaps          
Derivative [Line Items]          
Notional Amount 45,895   45,895   31,252
Derivative assets, fair value $ 9   $ 9   $ 129
Derivative liabilities, fair value $ 404   $ 404   $ 30
Derivatives designated as hedges | Foreign currency forwards          
Derivative [Line Items]          
Notional Amount 1,119   1,119   2,302
Derivative assets, fair value $ 73   $ 73   $ 81
Derivative liabilities, fair value $ 8   $ 8   $ 34
Derivatives designated as hedges | Cross Currency Interest Rate Contract          
Derivative [Line Items]          
Notional Amount 3,547   3,547   4,347
Derivative assets, fair value $ 37   $ 37   $ 86
Derivative liabilities, fair value 269   269   242
Derivatives not designated as hedges          
Derivative [Line Items]          
Total derivative liabilities 21,856   21,856   19,467
Derivative Asset, Including Embedded Derivatives $ 6,958   $ 6,958   $ 5,569
Derivatives not designated as hedges | Foreign currency swaps          
Derivative [Line Items]          
Notional Amount 30,352   30,352   19,248
Derivative assets, fair value $ 490   $ 490   $ 230
Derivative liabilities, fair value $ 417   $ 417   $ 744
Derivatives not designated as hedges | Interest rate swaps          
Derivative [Line Items]          
Notional Amount 27,798   27,798   14,606
Derivative assets, fair value $ 166   $ 166   $ 72
Derivative liabilities, fair value $ 1,240   $ 1,240   $ 295
Derivatives not designated as hedges | Equity options          
Derivative [Line Items]          
Notional Amount 115,246   115,246   97,259
Derivative assets, fair value $ 8,323   $ 8,323   $ 6,905
Derivative liabilities, fair value $ 735   $ 735   $ 170
Derivatives not designated as hedges | Futures          
Derivative [Line Items]          
Notional Amount 73   73   890
Derivative assets, fair value $ 128   $ 128   $ 192
Derivative liabilities, fair value $ 0   $ 0   $ 1
Derivatives not designated as hedges | Foreign currency forwards          
Derivative [Line Items]          
Notional Amount 38,576   38,576   47,486
Derivative assets, fair value $ 954   $ 954   $ 857
Derivative liabilities, fair value $ 3,170   $ 3,170   $ 3,356
Derivatives not designated as hedges | Other swaps          
Derivative [Line Items]          
Notional Amount 3,891   3,891   2,845
Derivative assets, fair value $ 230   $ 230   $ 78
Derivative liabilities, fair value 13   13   2
Derivatives not designated as hedges | Funds withheld at interest          
Derivative [Line Items]          
Embedded derivative assets, fair value (3,333)   (3,333)   (2,765)
Embedded derivative liabilities, fair value (132)   (132)   150
Derivatives not designated as hedges | Interest Sensitive Contracts          
Derivative [Line Items]          
Embedded derivative assets, fair value 0   0   0
Embedded derivative liabilities, fair value $ 16,413   $ 16,413   $ 14,749
Net Investment Hedging | Derivatives designated as hedges | Foreign currency forwards          
Derivative [Line Items]          
Notional Amount 224   224   234
Derivative assets, fair value $ 6   $ 6   $ 0
Derivative liabilities, fair value 0   0   $ 0
Fair Value Hedging | Derivatives designated as hedges | Foreign currency swaps          
Derivative [Line Items]          
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net, Recorded in Other Comprehensive Income (215) $ 41 (171) $ 61  
Fair Value Hedging | Derivatives designated as hedges | Foreign currency swaps | Income Statement Location [Axis]: us-gaap:GainLossOnInvestments          
Derivative [Line Items]          
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net 0 0 0 0  
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments 81 (9) 322 (1,022)  
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge (76) 29 (330) 1,087  
Derivative, Fair Value Hedge, Included in Effectiveness, Gain (Loss) 5 20 (8) 65  
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Amortization Approach 0 0 0 0  
Fair Value Hedging | Derivatives designated as hedges | Interest rate swaps | Income Statement Location [Axis]: us-gaap:GainLossOnInvestments          
Derivative [Line Items]          
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net 0 0 0 0  
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments (877) 24 (1,176) 218  
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge 803 (17) 1,103 (191)  
Derivative, Fair Value Hedge, Included in Effectiveness, Gain (Loss) (74) 7 (73) 27  
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Amortization Approach 0 0 0 0  
Fair Value Hedging | Derivatives designated as hedges | Foreign currency forwards          
Derivative [Line Items]          
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net, Recorded in Other Comprehensive Income 0 12 (2) 41  
Fair Value Hedging | Derivatives designated as hedges | Foreign currency forwards | Income Statement Location [Axis]: us-gaap:GainLossOnInvestments          
Derivative [Line Items]          
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net 0 0 0 0  
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments 2 15 47 (335)  
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge (2) (25) (44) 307  
Derivative, Fair Value Hedge, Included in Effectiveness, Gain (Loss) 0 (10) 3 (28)  
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Amortization Approach 4 8 20 27  
Fair Value Hedging | Derivatives designated as hedges | Cross Currency Interest Rate Contract | Income Statement Location [Axis]: us-gaap:GainLossOnInvestments          
Derivative [Line Items]          
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net 0 0 0 0  
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments (15) (34) (83) 447  
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge 33 13 112 (451)  
Derivative, Fair Value Hedge, Included in Effectiveness, Gain (Loss) 18 (21) 29 (4)  
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Amortization Approach 0 0 0 0  
Fair Value Hedging | Derivatives designated as hedges | Cross Currency Interest Rate Contract | Income Statement Location [Axis]: ahl:InterestSensitiveContractBenefitsExpense          
Derivative [Line Items]          
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net 0 0 0 0  
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments 22 23 67 71  
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge (20) (23) (64) (70)  
Derivative, Fair Value Hedge, Included in Effectiveness, Gain (Loss) 2 0 3 1  
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Amortization Approach $ 0 $ 0 $ 0 $ 0