Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Aug. 03, 2015
Document And Entity Information [Abstract]
Entity Registrant Name	ASSURED GUARANTY LTD
Entity Central Index Key	0001273813
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		146,508,128
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2