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
Mar. 31, 2026
Mar. 31, 2025
Segment Reporting Information [Line Items]    
Revenues $ 261 $ 345
Expenses 227 169
Equity in Earnings (Losses) of Investees 31 53
Less: Provision (benefit) for income taxes (20) 44
Less: Noncontrolling interest (3) 9
Net Income (Loss) Attributable to AGL 88 176
Subtotal    
Segment Reporting Information [Line Items]    
Revenues   265
Expenses   106
Equity in Earnings (Losses) of Investees   53
Less: Provision (benefit) for income taxes   41
Less: Noncontrolling interest   9
Net Income (Loss) Attributable to AGL   162
Realized gains (losses) on investments    
Segment Reporting Information [Line Items]    
Revenues (15) (16)
Net Income (Loss) Attributable to AGL (15) (16)
Non-credit impairment-related fair value gains (losses) on credit derivatives    
Segment Reporting Information [Line Items]    
Revenues (2) 61
Net Income (Loss) Attributable to AGL (2) (2)
Fair value gains (losses) of freestanding derivatives in the Annuity Reinsurance segment    
Segment Reporting Information [Line Items]    
Revenues (2)  
Net Income (Loss) Attributable to AGL (2)  
Realized and unrealized fair value gains (losses) of the embedded derivative in funds withheld    
Segment Reporting Information [Line Items]    
Revenues (2)  
Net Income (Loss) Attributable to AGL (2)  
Fair value gains (losses) on CCS    
Segment Reporting Information [Line Items]    
Revenues 6 2
Net Income (Loss) Attributable to AGL 6 2
Foreign exchange gains (losses) on remeasurement of certain assets and liabilities    
Segment Reporting Information [Line Items]    
Revenues (18) 33
Net Income (Loss) Attributable to AGL (18) 33
Tax effect    
Segment Reporting Information [Line Items]    
Less: Provision (benefit) for income taxes (6) 3
Net Income (Loss) Attributable to AGL 6 (3)
Subtotal    
Segment Reporting Information [Line Items]    
Revenues 294  
Expenses 227  
Equity in Earnings (Losses) of Investees 31  
Less: Provision (benefit) for income taxes (14)  
Less: Noncontrolling interest (3)  
Net Income (Loss) Attributable to AGL 115  
Operating Segments    
Segment Reporting Information [Line Items]    
Revenues 310 245
Expenses 186 68
Equity in Earnings (Losses) of Investees 14 43
Less: Provision (benefit) for income taxes (8) 40
Less: Noncontrolling interest 0 0
Net Income (Loss) Attributable to AGL 146 180
Operating Segments | Financial Guaranty    
Segment Reporting Information [Line Items]    
Revenues 182 239
Expenses 107 64
Equity in Earnings (Losses) of Investees 8 30
Less: Provision (benefit) for income taxes (19) 37
Less: Noncontrolling interest 0 0
Net Income (Loss) Attributable to AGL 102 168
Operating Segments | Annuity Reinsurance Segment    
Segment Reporting Information [Line Items]    
Revenues 10  
Expenses 11  
Equity in Earnings (Losses) of Investees 0  
Less: Provision (benefit) for income taxes (1)  
Less: Noncontrolling interest 0  
Net Income (Loss) Attributable to AGL 0  
Operating Segments | Asset Management    
Segment Reporting Information [Line Items]    
Revenues 118 6
Expenses 68 4
Equity in Earnings (Losses) of Investees 6 13
Less: Provision (benefit) for income taxes 12 3
Less: Noncontrolling interest 0 0
Net Income (Loss) Attributable to AGL 44 12
Corporate division    
Segment Reporting Information [Line Items]    
Revenues 8 4
Expenses 43 40
Equity in Earnings (Losses) of Investees 19 16
Less: Provision (benefit) for income taxes (1) 0
Less: Noncontrolling interest 0 0
Net Income (Loss) Attributable to AGL (15) (20)
Intersegment Eliminations    
Segment Reporting Information [Line Items]    
Revenues (24) 16
Expenses (2) (2)
Equity in Earnings (Losses) of Investees (2) (6)
Less: Provision (benefit) for income taxes (5) 1
Less: Noncontrolling interest (3) 9
Net Income (Loss) Attributable to AGL (16) 2
Intersegment Eliminations | Financial Guaranty    
Segment Reporting Information [Line Items]    
Revenues 2 2
Intersegment Eliminations | Annuity Reinsurance Segment    
Segment Reporting Information [Line Items]    
Revenues 0  
Intersegment Eliminations | Asset Management    
Segment Reporting Information [Line Items]    
Revenues $ 24 1
Reconciling items:    
Segment Reporting Information [Line Items]    
Expenses   $ 63