v3.26.1
Segment Information - Reconciliation of Net Income (Loss) Attributable to AGL to Segment Adjusted Operating Income (Loss) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting [Line Items]        
Revenues $ 195 $ 281 $ 456 $ 626
Expenses 135 151 362 320
Equity in Earnings (Losses) of Investees (11) 3 20 56
Less: Provision (benefit) for income taxes 9 27 (11) 71
Less: Noncontrolling interest 1 3 (2) 12
Net Income (Loss) Attributable to AGL 39 103 127 279
Subtotal        
Segment Reporting [Line Items]        
Revenues       483
Expenses       257
Equity in Earnings (Losses) of Investees       56
Less: Provision (benefit) for income taxes       58
Less: Noncontrolling interest       12
Net Income (Loss) Attributable to AGL       212
Realized Gain (Loss) On Investments        
Segment Reporting [Line Items]        
Revenues (10) (6) (25) (22)
Net Income (Loss) Attributable to AGL (10) (6) (25) (22)
Non-credit impairment-related fair value gains (losses) on credit derivatives        
Segment Reporting [Line Items]        
Revenues (1) (1) (3) 60
Net Income (Loss) Attributable to AGL (1) (1) (3) (3)
Fair value gains (losses) of freestanding derivatives in the Annuity Reinsurance segment        
Segment Reporting [Line Items]        
Revenues (1)   (3)  
Net Income (Loss) Attributable to AGL (1)   (3)  
Realized and unrealized fair value gains (losses) of the embedded derivative in funds withheld        
Segment Reporting [Line Items]        
Revenues     (2)  
Net Income (Loss) Attributable to AGL     (2)  
Fair value gains (losses) on CCS        
Segment Reporting [Line Items]        
Revenues (7) (1) (1) 1
Net Income (Loss) Attributable to AGL (7) (1) (1) 1
Foreign exchange gains (losses) on remeasurement of certain assets and liabilities        
Segment Reporting [Line Items]        
Revenues (1) 71 (19) 104
Net Income (Loss) Attributable to AGL (1) 71 (19) 104
Tax effect        
Segment Reporting [Line Items]        
Less: Provision (benefit) for income taxes (4) 10 (10) 13
Net Income (Loss) Attributable to AGL 4 (10) 10 (13)
Subtotal        
Segment Reporting [Line Items]        
Revenues 215 218 509  
Expenses 135 151 362  
Equity in Earnings (Losses) of Investees (11) 3 20  
Less: Provision (benefit) for income taxes 13 17 (1)  
Less: Noncontrolling interest 1 3 (2)  
Net Income (Loss) Attributable to AGL 55 50 170  
Operating Segments        
Segment Reporting [Line Items]        
Revenues 214 214 524 459
Expenses 100 114 286 182
Equity in Earnings (Losses) of Investees (15) 1 (1) 44
Less: Provision (benefit) for income taxes 16 21 8 61
Less: Noncontrolling interest 0 0 0 0
Net Income (Loss) Attributable to AGL 83 80 229 260
Operating Segments | Financial Guaranty        
Segment Reporting [Line Items]        
Revenues 199 199 381 438
Expenses 87 105 194 169
Equity in Earnings (Losses) of Investees (10) 2 (2) 32
Less: Provision (benefit) for income taxes 17 20 (2) 57
Less: Noncontrolling interest 0 0 0 0
Net Income (Loss) Attributable to AGL 85 76 187 244
Operating Segments | Annuity Reinsurance Segment        
Segment Reporting [Line Items]        
Revenues 15   25  
Expenses 13   24  
Equity in Earnings (Losses) of Investees 0   0  
Less: Provision (benefit) for income taxes 0   (1)  
Less: Noncontrolling interest 0   0  
Net Income (Loss) Attributable to AGL 2   2  
Operating Segments | Asset Management        
Segment Reporting [Line Items]        
Revenues 0 15 118 21
Expenses 0 9 68 13
Equity in Earnings (Losses) of Investees (5) (1) 1 12
Less: Provision (benefit) for income taxes (1) 1 11 4
Less: Noncontrolling interest 0 0 0 0
Net Income (Loss) Attributable to AGL (4) 4 40 16
Corporate division        
Segment Reporting [Line Items]        
Revenues 3 4 11 8
Expenses 38 39 81 79
Equity in Earnings (Losses) of Investees 4 3 23 19
Less: Provision (benefit) for income taxes (3) (3) (4) (3)
Less: Noncontrolling interest 0 0 0 0
Net Income (Loss) Attributable to AGL (28) (29) (43) (49)
Intersegment Eliminations        
Segment Reporting [Line Items]        
Revenues (2) 0 (26) 16
Expenses (3) (2) (5) (4)
Equity in Earnings (Losses) of Investees 0 (1) (2) (7)
Less: Provision (benefit) for income taxes 0 (1) (5) 0
Less: Noncontrolling interest 1 3 (2) 12
Net Income (Loss) Attributable to AGL 0 (1) (16) 1
Intersegment Eliminations | Financial Guaranty        
Segment Reporting [Line Items]        
Revenues 2 3 4 5
Intersegment Eliminations | Annuity Reinsurance Segment        
Segment Reporting [Line Items]        
Revenues 0   0  
Intersegment Eliminations | Asset Management        
Segment Reporting [Line Items]        
Revenues $ 0 $ 2 $ 24 3
Reconciling items:        
Segment Reporting [Line Items]        
Expenses       $ 63