v3.25.2
Cover Page - shares
6 Months Ended
Jun. 30, 2025
Aug. 06, 2025
Entity Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2025  
Document Transition Report false  
Entity File Number 001-32141  
Entity Registrant Name ASSURED GUARANTY LTD.  
Entity Incorporation, State or Country Code D0  
Entity Tax Identification Number 98-0429991  
Entity Address, Address Line One 30 Woodbourne Avenue  
Entity Address, City or Town Hamilton  
Entity Address, Postal Zip Code HM 08  
Entity Address, Country BM  
City Area Code 441  
Local Phone Number 279-5700  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   47,615,221
Entity Central Index Key 0001273813  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
New York Stock Exchange | Common Shares Outstanding    
Entity Information [Line Items]    
Title of 12(b) Security Common Shares  
Trading Symbol AGO  
Security Exchange Name NYSE  
New York Stock Exchange | Assured Guaranty US Holdings Inc. 6.125% Senior Notes Due 2028    
Entity Information [Line Items]    
Title of 12(b) Security Assured Guaranty US Holdings Inc. 6.125% Senior Notes due 2028 (and the related guarantee of Registrant)  
Trading Symbol AGO/28  
Security Exchange Name NYSE  
New York Stock Exchange | Assured Guaranty US Holdings Inc. 3.150% Senior Notes due 2031 (and the related guarantee of Registrant)    
Entity Information [Line Items]    
Title of 12(b) Security Assured Guaranty US Holdings Inc. 3.150% Senior Notes due 2031 (and the related guarantee of Registrant)  
Trading Symbol AGO/31  
Security Exchange Name NYSE  
New York Stock Exchange | Assured Guaranty US Holdings Inc. 3.600% Senior Notes due 2051 (and the related guarantee of Registrant)    
Entity Information [Line Items]    
Title of 12(b) Security Assured Guaranty US Holdings Inc. 3.600% Senior Notes due 2051 (and the related guarantee of Registrant)  
Trading Symbol AGO/51  
Security Exchange Name NYSE