XML 121 R99.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Investments and Cash - Investment Portfolio Carrying Value (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Schedule of Cost-method Investments [Line Items] |  |
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss | $ 6,307 | $ 7,119
Fixed-maturity securities, trading, at fair value | 318 | 303
Short-term investments, at fair value | 1,661 | 810
Other invested assets | 829 | 133
Total investments | 9,115 | 8,365
Externally managed |  |
Schedule of Cost-method Investments [Line Items] |  |
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss | 5,372 | 5,824
Externally managed | Internal |  |
Schedule of Cost-method Investments [Line Items] |  |
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss | 318 | 305
Puerto Rico, New Recovery Bonds |  |
Schedule of Cost-method Investments [Line Items] |  |
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss | 14 | 358
Other |  |
Schedule of Cost-method Investments [Line Items] |  |
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss | 462 | 431
Other | Assured IM |  |
Schedule of Cost-method Investments [Line Items] |  |
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss | 223 | 232
Loss Mitigation Securities |  |
Schedule of Cost-method Investments [Line Items] |  |
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss | $ 459 | $ 506
BIG |  |
Schedule of Cost-method Investments [Line Items] |  |
Fixed-maturity securities rated as BIG | 7.80% | 7.40%
Not Internally Rated |  |
Schedule of Cost-method Investments [Line Items] |  |
Fixed-maturity securities rated as BIG | 1.40% | 5.90%
Sound Point |  |
Schedule of Cost-method Investments [Line Items] |  |
Other invested assets | $ 429 | $ 0
Other |  |
Schedule of Cost-method Investments [Line Items] |  |
Other invested assets | 394 | 123
Other |  |
Schedule of Cost-method Investments [Line Items] |  |
Other invested assets | $ 6 | $ 10

X
- Definition Fixed-Maturity Investments, Non-Investment Grade, Percent + References No definition available. + Details
Name: | ago_FixedMaturityInvestmentsNonInvestmentGradePercent
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479130/326-30-45-1 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Sum of the carrying amounts as of the balance sheet date of all investments. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)(h)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1 + Details
Name: | us-gaap_Investments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investments classified as other. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(12)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_OtherInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(8)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(5)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(4)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1 + Details
Name: | us-gaap_ShortTermInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481830/320-10-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(2)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483467/210-10-45-1 + Details
Name: | us-gaap_TradingSecuritiesDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=ago_SecuritiesManagedExternallyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ago_InternalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=ago_RecoveryBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=ago_OtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ago_AssuredIMMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=ago_InsuredFinancialObligationsLossMitigationSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_InternalNoninvestmentGradeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=ago_NotInternallyRatedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ago_SoundPointCapitalManagementLPMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ago_EquityMethodInvestmentsOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ago_OtherInvestmentsInternallyManagedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |