XML 52 R40.htm IDEA: XBRL DOCUMENT
v3.23.2

Reserve for Losses and Loss Adjustment Expenses - Prior year development (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | $ 121 | $ 171 | $ 257 | $ 312
Operating segments | Insurance |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | $ 12 | $ 7 | $ 24 | $ 14
Percentage of prior year development | 0.90% | 0.60% | 0.90% | 0.70%
Operating segments | Insurance | Medium tailed lines |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | $ (18) |  | $ (31) |
Operating segments | Insurance | Medium tailed lines | Programs |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | (8) |  | (6) | $ 5
Operating segments | Insurance | Medium tailed lines | Professional liability |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | (5) | $ (6) | (24) | (14)
Operating segments | Insurance | Medium tailed lines | Contract binding |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  |  |  | (6)
Operating segments | Insurance | Medium tailed lines | Marine |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | (4) | 3 |  | 6
Operating segments | Insurance | Long tailed lines | Executive assurance |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | 6 | (6) | 16 |
Operating segments | Insurance | Long tailed lines | Alternative markets |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  |  | 5 |
Operating segments | Insurance | Long tailed lines | Healthcare |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  |  | (5) |
Operating segments | Insurance | Long tailed lines | Construction and national accounts |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  |  |  | (8)
Operating segments | Insurance | Short tailed lines |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  | 14 |  | 33
Operating segments | Insurance | Short tailed lines | Property excluding marine |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | 16 |  | 25 |
Operating segments | Insurance | Short tailed lines | Warranty and lenders solutions |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | 7 |  | 14 |
Operating segments | Insurance | Short tailed lines | Lenders products |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  | 12 |  | 31
Operating segments | Insurance | Medium tailed and long tailed lines |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  | (7) |  | (19)
Operating segments | Insurance | Short tailed and long tailed lines |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | 30 |  | 55 |
Operating segments | Reinsurance |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | $ 29 | $ 46 | $ 82 | $ 78
Percentage of prior year development | 2.20% | 5.00% | 3.00% | 4.60%
Operating segments | Reinsurance | Medium tailed lines | Marine and aviation |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | $ 7 | $ 4 | $ 9 | $ 15
Operating segments | Reinsurance | Long tailed lines |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | (22) | (8) | (21) | (11)
Operating segments | Reinsurance | Long tailed lines | Casualty |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | (22) |  | (19) |
Operating segments | Reinsurance | Short tailed and medium tailed lines |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | 51 | 54 | 103 | 90
Operating segments | Reinsurance | Short tailed lines |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  |  |  | 75
Operating segments | Reinsurance | Short tailed lines | Property catastrophe |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  | 6 | 7 | 10
Operating segments | Reinsurance | Short tailed lines | Property other than property catastrophe |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | 23 | 32 | 46 | 47
Operating segments | Reinsurance | Short tailed lines | Other specialty lines and other lines |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | 21 |  |  |
Operating segments | Reinsurance | Short tailed lines | Other specialty lines |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  | 13 | 27 | 18
Operating segments | Reinsurance | Short tailed lines | Other lines |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) |  |  | 13 |
Operating segments | Mortgage |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Prior year development favorable (unfavorable) | $ 80 | $ 118 | $ 151 | $ 220
Percentage of prior year development | 27.20% | 39.90% | 25.60% | 37.60%

X
- Definition The ratio of the prior year development to net earned premiums for the given year in question. + References No definition available. + Details
Name: | acgl_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsPriorYearsPercentage
Namespace Prefix: | acgl_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

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_CausesOfIncreaseDecreaseInLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480081/944-40-50-3 + Details
Name: | us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=acgl_InsuranceSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | acgl_ReinsuranceBusinessByTypeAxis=acgl_MediumTailedLinesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_ProgramsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=us-gaap_ProfessionalLiabilityInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_ContractBindingBusinessMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_MarineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | acgl_ReinsuranceBusinessByTypeAxis=acgl_LongTailedLinesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=us-gaap_DirectorsAndOfficersLiabilityInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_AlternativeMarketsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_HealthcareMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_ConstructionAndNationalAccountsProductLineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | acgl_ReinsuranceBusinessByTypeAxis=acgl_ShortTailedLinesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_PropertyExcludingMarineProductLineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_WarrantyAndLendersSolutionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_LendersProductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | acgl_ReinsuranceBusinessByTypeAxis=acgl_MediumTailedAndLongTailedLinesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | acgl_ReinsuranceBusinessByTypeAxis=acgl_ShortTailedAndLongTailedLinesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=acgl_ReinsuranceSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_MarineAndAviationProductLinesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_CasualtyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | acgl_ReinsuranceBusinessByTypeAxis=acgl_ShortTailedAndMediumTailedLinesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_PropertyCatastropheMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_PropertyOtherThanPropertyCatastropheMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_OtherSpecialtyLinesAndOtherLinesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_OtherSpecialtyLinesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=acgl_OtherLinesOfBusinessMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=acgl_MortgageSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |