XML 162 R135.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Leases - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023
Leases [Abstract] |  |
ROU assets | $ 60 | $ 71
Lease liabilities | $ 84 | $ 97
Weighted average remaining lease term | 7 years 1 month 6 days | 7 years 9 months 18 days
Weighted average discount rate | 2.65% | 2.60%
ROU asset impairment | $ 2 | $ 3

X
- Definition Finance and Operating Lease, Weighted Average Discount Rate, Percent + References No definition available. + Details
Name: | ago_FinanceAndOperatingLeaseWeightedAverageDiscountRatePercent
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Finance and Operating Lease, Weighted Average Remaining Lease Term + References No definition available. + Details
Name: | ago_FinanceAndOperatingLeaseWeightedAverageRemainingLeaseTerm
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Finance and Operating Lease, Liability + References No definition available. + Details
Name: | ago_FinanceandOperatingLeaseLiability
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Finance and Operating Lease, Right-of-Use Asset + References No definition available. + Details
Name: | ago_FinanceandOperatingLeaseRightofUseAsset
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LeasesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of loss from impairment of right-of-use asset from operating lease. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 25 -Paragraph 6 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479365/842-20-25-6 + Details
Name: | us-gaap_OperatingLeaseImpairmentLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration