v3.26.3
Segment Information - Reconciliation of Net Income (Loss) Attributable to AGL to Segment Adjusted Operating Income (Loss) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Segment Reporting [Line Items]        
Revenues $ 214 $ 207 $ 670 $ 833
Expenses 127 92 489 412
Equity in Earnings (Losses) of Investees 12 20 32 76
Less: Provision (benefit) for income taxes 19 21 8 92
Less: Noncontrolling interest 2 9 0 21
Net Income (Loss) Attributable to AGL 78 105 205 384
Subtotal        
Segment Reporting [Line Items]        
Revenues       713
Expenses       349
Equity in Earnings (Losses) of Investees       76
Less: Provision (benefit) for income taxes       83
Less: Noncontrolling interest       21
Net Income (Loss) Attributable to AGL       336
Realized Gain (Loss) On Investments        
Segment Reporting [Line Items]        
Revenues (11) (10) (36) (32)
Net Income (Loss) Attributable to AGL (11) (10) (36) (32)
Non-credit impairment-related fair value gains (losses) on credit derivatives        
Segment Reporting [Line Items]        
Revenues   1 (3) 61
Net Income (Loss) Attributable to AGL   1 (3) (2)
Fair value gains (losses) of freestanding derivatives in the Annuity Reinsurance segment        
Segment Reporting [Line Items]        
Revenues 6   3  
Net Income (Loss) Attributable to AGL 6   3  
Realized and unrealized fair value gains (losses) of the embedded derivative in funds withheld        
Segment Reporting [Line Items]        
Revenues (3)   (5)  
Net Income (Loss) Attributable to AGL (3)   (5)  
Fair value gains (losses) on CCS        
Segment Reporting [Line Items]        
Revenues (2) 8 (3) 9
Net Income (Loss) Attributable to AGL (2) 8 (3) 9
Foreign exchange gains (losses) on remeasurement of certain assets and liabilities        
Segment Reporting [Line Items]        
Revenues (1) (22) (20) 82
Net Income (Loss) Attributable to AGL (1) (22) (20) 82
Tax effect        
Segment Reporting [Line Items]        
Less: Provision (benefit) for income taxes (3) (4) (13) 9
Net Income (Loss) Attributable to AGL 3 4 13 (9)
Subtotal        
Segment Reporting [Line Items]        
Revenues 225 230 734  
Expenses 127 92 489  
Equity in Earnings (Losses) of Investees 12 20 32  
Less: Provision (benefit) for income taxes 22 25 21  
Less: Noncontrolling interest 2 9 0  
Net Income (Loss) Attributable to AGL 86 124 256  
Operating Segments        
Segment Reporting [Line Items]        
Revenues 223 214 747 673
Expenses 93 55 379 237
Equity in Earnings (Losses) of Investees 11 16 10 60
Less: Provision (benefit) for income taxes 23 27 31 88
Less: Noncontrolling interest 0 0 0 0
Net Income (Loss) Attributable to AGL 118 148 347 408
Operating Segments | Financial Guaranty        
Segment Reporting [Line Items]        
Revenues 207 206 588 644
Expenses 78 51 272 220
Equity in Earnings (Losses) of Investees 9 16 7 48
Less: Provision (benefit) for income taxes 23 26 21 83
Less: Noncontrolling interest 0 0 0 0
Net Income (Loss) Attributable to AGL 115 145 302 389
Operating Segments | Annuity Reinsurance Segment        
Segment Reporting [Line Items]        
Revenues 16   41  
Expenses 15   39  
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 1   3  
Operating Segments | Asset Management        
Segment Reporting [Line Items]        
Revenues 0 8 118 29
Expenses 0 4 68 17
Equity in Earnings (Losses) of Investees 2 0 3 12
Less: Provision (benefit) for income taxes 0 1 11 5
Less: Noncontrolling interest 0 0 0 0
Net Income (Loss) Attributable to AGL 2 3 42 19
Corporate division        
Segment Reporting [Line Items]        
Revenues 2 3 13 11
Expenses 35 38 116 117
Equity in Earnings (Losses) of Investees 1 9 24 28
Less: Provision (benefit) for income taxes (1) (2) (5) (5)
Less: Noncontrolling interest 0 0 0 0
Net Income (Loss) Attributable to AGL (31) (24) (74) (73)
Intersegment Eliminations        
Segment Reporting [Line Items]        
Revenues 0 13 (26) 29
Expenses (1) (1) (6) (5)
Equity in Earnings (Losses) of Investees 0 (5) (2) (12)
Less: Provision (benefit) for income taxes 0 0 (5) 0
Less: Noncontrolling interest 2 9 0 21
Net Income (Loss) Attributable to AGL (1) 0 (17) 1
Intersegment Eliminations | Financial Guaranty        
Segment Reporting [Line Items]        
Revenues 2 2 6 7
Intersegment Eliminations | Annuity Reinsurance Segment        
Segment Reporting [Line Items]        
Revenues 0   0  
Intersegment Eliminations | Asset Management        
Segment Reporting [Line Items]        
Revenues $ 0 $ 2 $ 24 5
Reconciling items:        
Segment Reporting [Line Items]        
Expenses       $ 63