v3.26.1
Outstanding Exposure - BIG Net Par Outstanding (Details)
$ in Millions
Jun. 30, 2026
USD ($)
risk
Dec. 31, 2025
USD ($)
risk
Schedule of Insured Financial Obligations [Line Items]    
Net par outstanding, credit derivative $ 3,600 $ 3,800
Net 281,400 277,100
BIG    
Schedule of Insured Financial Obligations [Line Items]    
Net par outstanding, financial guaranty insurance 8,470 8,730
Net par outstanding, credit derivative 30 30
Net $ 8,500 $ 8,760
Number of risks, financial guaranty insurance | risk 191 195
Number of risks, credit derivative | risk 7 7
Number of risks | risk 198 202
BIG | BIG 1    
Schedule of Insured Financial Obligations [Line Items]    
Net par outstanding, financial guaranty insurance $ 2,360 $ 3,710
Net par outstanding, credit derivative 30 30
Net $ 2,390 $ 3,740
Number of risks, financial guaranty insurance | risk 83 87
Number of risks, credit derivative | risk 3 3
Number of risks | risk 86 90
BIG | BIG 2    
Schedule of Insured Financial Obligations [Line Items]    
Net par outstanding, financial guaranty insurance $ 4,940 $ 3,810
Net par outstanding, credit derivative 0 0
Net $ 4,940 $ 3,810
Number of risks, financial guaranty insurance | risk 15 13
Number of risks, credit derivative | risk 1 1
Number of risks | risk 16 14
BIG | BIG 3    
Schedule of Insured Financial Obligations [Line Items]    
Net par outstanding, financial guaranty insurance $ 1,170 $ 1,210
Net par outstanding, credit derivative 0 0
Net $ 1,170 $ 1,210
Number of risks, financial guaranty insurance | risk 93 95
Number of risks, credit derivative | risk 3 3
Number of risks | risk 96 98