XML 141 R120.htm IDEA: XBRL DOCUMENT v3.24.0.1

Statutory Financial Information (Narrative) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Statutory Accounting Practices [Line Items]
Amount of cash and investments held as funds at Lloyd's	$ 1,000.0
Parent Company [Member]
Statutory Accounting Practices [Line Items]
Amount of cash and investments held as funds at Lloyd's	380.4
United States [Member]
Statutory Accounting Practices [Line Items]
Amount available for dividend payment	592.5
Bermuda [Member]
Statutory Accounting Practices [Line Items]
Amount available for dividend payment	$ 588.3

X

- Definition

The amount of cash and investments comprising the funds at Lloyd's.

+ References

No definition available.

+ Details

Name:	mkl_FundsAtLloyds
Namespace Prefix:	mkl_
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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(23)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

+ Details

Name:	us-gaap_StatutoryAccountingPracticesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of dividends available for payment after computation of statutory restrictions on capital surplus.

+ References

No definition available.

+ Details

Name:	us-gaap_StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatutoryAccountingPracticesByJurisdictionAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatutoryAccountingPracticesByJurisdictionAxis=country_BM
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: