XML 114 R94.htm IDEA: XBRL DOCUMENT
v3.23.1

Income Taxes - Narrative (Details) - USD ($) $ in Millions |  | 3 Months Ended | 12 Months Ended | 72 Months Ended |
--- | --- | --- | --- | --- | ---
Apr. 01, 2023 | Mar. 31, 2023 | Dec. 31, 2023 | Mar. 31, 2023 | Dec. 31, 2022
Income Taxes [Line Items] |  |  |  |  |
Valuation allowance |  | $ 5 |  | $ 5 | $ 5
Realization assessment period |  | 3 years |  |  |
Foreign Tax Authority |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |
Corporate tax rate |  | 21.00% |  |  |
United Kingdom |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |
Corporate tax rate |  |  |  | 19.00% |
United Kingdom | Subsequent Event |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |
Corporate tax rate | 25.00% |  | 23.50% |  |
France |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |
Corporate tax rate |  | 25.00% |  |  |

X
- Definition Represents the period for which the entity has considered cumulative operating income for the assessment of realization of deferred tax assets. + References No definition available. + Details
Name: | ago_DeferredTaxAssetsRealizationAssessmentPeriodForWhichCumulativeOperatingIncomeConsidered
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition [Line Items] for Income Taxes [Table] + References No definition available. + Details
Name: | ago_IncomeTaxesLineItems
Namespace Prefix: | ago_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of domestic federal statutory tax rate applicable to pretax income (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.Fact.4) -URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)(2)) -URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32687-109319 + Details
Name: | us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from tax credit carryforwards for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32537-109319 + Details
Name: | us-gaap_TaxCreditCarryforwardValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_ForeignCountryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=country_GB
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=country_FR
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |