Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2022	Feb. 24, 2023	Jun. 30, 2022
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 3,341,929,790
Entity Common Stock, Shares Outstanding		59,056,267
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCECertain portions of Registrant’s definitive proxy statement relating to its 2023 Annual General Meeting of Shareholders to be held on May 3, 2023, are incorporated by reference to Part III of this report.
Entity Central Index Key	0001273813
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
New York Stock Exchange | Common Shares
Document 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. 5.000% Senior Notes due 2024 (and the related guarantee of Registrant)
Document Information [Line Items]
Title of 12(b) Security	Assured Guaranty US Holdings Inc. 5.000% Senior Notes due 2024 (and the related guarantee of Registrant)
Trading Symbol	AGO 24
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)
Document 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)
Document 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