XML 86 R77.htm IDEA: XBRL DOCUMENT
v3.22.2.2

Reserves for Loss and Loss Expenses (Narrative) (Details) - USD ($) $ in Millions | 9 Months Ended
--- | ---
Sep. 30, 2022 | Sep. 30, 2021
Liability for Claims and Claims Adjustment Expense [Line Items] |  |
Net of loss reserve discounts | $ 26.0 | $ 16.0
Increase (decrease) in estimates for claims | 20.0 | (13.0)
Adjustment expense | 37.0 | 5.0
Liability recognized for best estimate net of reinsurance | 348.0 |
Liability recognized for best estimate net of reinsurance, current accident year losses | 4.0 |
Liability recognized for best estimate net of reinsurance, reported losses | 343.0 |
Liability recognized for best estimate net of reinsurance, incurred but not reported (IBNR) | 5.0 |
Insurance |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |
Liability recognized for best estimate net of reinsurance | 299.0 |
Liability recognized for best estimate net of reinsurance, current accident year losses | 2.0 |
Favorable reserve development net of premium offsets |  | 8.0
Unfavorable reserve development net of premium offsets | 33.0 |
Reinsurance & Monoline Excess |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |
Liability recognized for best estimate net of reinsurance | 49.0 |
Liability recognized for best estimate net of reinsurance, current accident year losses | 2.0 |
Unfavorable reserve development net of premium offsets | $ 4.0 | $ 3.0

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_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems
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 -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437 + Details
Name: | us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Current year monetary amount of the change in worker's compensation reserve liability resulting from the discount applied to reduce the reserve to present value. + References No definition available. + Details
Name: | us-gaap_WorkersCompensationDiscountAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Favorable Reserve Development Net Of Premium Offsets + References No definition available. + Details
Name: | wrb_FavorableReserveDevelopmentNetOfPremiumOffsets
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Liability for Claims and Claims Adjustment Expense, Net Of Reinsurance, Current Accident Year Losses + References No definition available. + Details
Name: | wrb_LiabilityForClaimsAndClaimsAdjustmentExpenseNetOfReinsuranceCurrentAccidentYearLosses
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Liability for Claims and Claims Adjustment Expense, Net Of Reinsurance, Incurred but Not Reported (IBNR) Claims, Amount + References No definition available. + Details
Name: | wrb_LiabilityForClaimsAndClaimsAdjustmentExpenseNetOfReinsuranceIncurredButNotReportedIBNRClaimsAmount
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Liability for Claims and Claims Adjustment Expense, Net Of Reinsurance, Reported Claims, Amount + References No definition available. + Details
Name: | wrb_LiabilityForClaimsAndClaimsAdjustmentExpenseNetOfReinsuranceReportedClaimsAmount
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims Undiscounted Basis Prior Years, Increase (Decrease) + References No definition available. + Details
Name: | wrb_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsUndiscountedBasisPriorYearsIncreaseDecrease
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Liability for Claims and Claims Adjustment Expense, Net Of Reinsurance + References No definition available. + Details
Name: | wrb_LiabilityforClaimsandClaimsAdjustmentExpenseNetOfReinsurance
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Unfavorable Reserve Development Net Of Premium Offsets + References No definition available. + Details
Name: | wrb_UnfavorableReserveDevelopmentNetOfPremiumOffsets
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

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