v3.25.2
Outstanding Exposure - Financial Guaranty Portfolio by Internal Rating (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Schedule of Insured Financial Obligations [Line Items]    
Net $ 272,778 $ 261,552
% of total net par outstanding 100.00% 100.00%
AAA    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 2,996 $ 3,081
% of total net par outstanding 1.10% 1.20%
AA    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 25,825 $ 25,962
% of total net par outstanding 9.50% 9.90%
A    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 134,180 $ 127,617
% of total net par outstanding 49.20% 48.80%
BBB    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 99,269 $ 94,710
% of total net par outstanding 36.40% 36.20%
BIG    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 10,508 $ 10,182
% of total net par outstanding 3.80% 3.90%
Public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 261,848 $ 250,375
Public finance | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 208,716 $ 201,175
% of total net par outstanding 100.00% 100.00%
Public finance | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 53,132 $ 49,200
% of total net par outstanding 100.00% 100.00%
Public finance | AAA | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 23 $ 25
% of total net par outstanding 0.00% 0.00%
Public finance | AAA | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 1,966 $ 2,074
% of total net par outstanding 3.70% 4.20%
Public finance | AA | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 17,572 $ 17,664
% of total net par outstanding 8.50% 8.80%
Public finance | AA | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 2,872 $ 2,854
% of total net par outstanding 5.40% 5.80%
Public finance | A | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 118,435 $ 111,502
% of total net par outstanding 56.70% 55.50%
Public finance | A | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 12,888 $ 13,046
% of total net par outstanding 24.30% 26.50%
Public finance | BBB | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 70,136 $ 69,096
% of total net par outstanding 33.60% 34.30%
Public finance | BBB | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 28,314 $ 24,828
% of total net par outstanding 53.30% 50.50%
Public finance | BIG    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 9,642 $ 9,286
Public finance | BIG | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 2,550 $ 2,888
% of total net par outstanding 1.20% 1.40%
Public finance | BIG | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 7,092 $ 6,398
% of total net par outstanding 13.30% 13.00%
Structured finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 10,930 $ 11,177
Structured finance | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 8,166 $ 8,453
% of total net par outstanding 100.00% 100.00%
Structured finance | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 2,764 $ 2,724
% of total net par outstanding 100.00% 100.00%
Structured finance | AAA | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 486 $ 512
% of total net par outstanding 6.00% 6.10%
Structured finance | AAA | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 521 $ 470
% of total net par outstanding 18.80% 17.30%
Structured finance | AA | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 5,314 $ 5,386
% of total net par outstanding 65.10% 63.70%
Structured finance | AA | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 67 $ 58
% of total net par outstanding 2.50% 2.10%
Structured finance | A | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 761 $ 952
% of total net par outstanding 9.30% 11.30%
Structured finance | A | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 2,096 $ 2,117
% of total net par outstanding 75.80% 77.70%
Structured finance | BBB | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 739 $ 707
% of total net par outstanding 9.00% 8.30%
Structured finance | BBB | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 80 $ 79
% of total net par outstanding 2.90% 2.90%
Structured finance | BIG    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 866 $ 896
Structured finance | BIG | United States    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 866 $ 896
% of total net par outstanding 10.60% 10.60%
Structured finance | BIG | Non-U.S. public finance    
Schedule of Insured Financial Obligations [Line Items]    
Net $ 0 $ 0
% of total net par outstanding 0.00% 0.00%