XML 98 R88.htm IDEA: XBRL DOCUMENT
v3.22.1

Business Segments (Net Premiums Earned By Major Line of Business) (Details) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2022 | Mar. 31, 2021
Revenue from External Customer [Line Items] |  |
Net premiums earned | $ 2,249,087 | $ 1,849,956
Insurance |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned |  | 1,604,979
Insurance | Operating Segments |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned | 1,962,835 | 1,604,979
Insurance | Other liability |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned | 754,456 | 611,404
Insurance | Short-tail lines |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned | 375,212 | 324,740
Insurance | Workers' compensation |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned | 285,423 | 267,449
Insurance | Commercial automobile |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned | 282,234 | 220,761
Insurance | Professional liability |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned | 265,510 | 180,626
Reinsurance & Monoline Excess |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned |  | 244,977
Reinsurance & Monoline Excess | Operating Segments |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned | 286,252 | 244,977
Reinsurance & Monoline Excess | Casualty reinsurance |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned | 184,122 | 149,638
Reinsurance & Monoline Excess | Monoline excess |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned | 50,234 | 49,466
Reinsurance & Monoline Excess | Property reinsurance |  |
Revenue from External Customer [Line Items] |  |
Net premiums earned | $ 51,896 | $ 45,873

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

X
- Definition Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums earned. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(1)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17(Column E)) -URI http://asc.fasb.org/extlink&oid=120401096&loc=d3e574992-122915 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(c)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
Name: | us-gaap_PremiumsEarnedNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

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

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

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

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

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

X
- Details
Name: | srt_ProductOrServiceAxis=wrb_ProductsLiabilityMember
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: |

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

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

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