Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	$ 3,660,108	$ 3,486,395
Allowance for credit losses	(33,309)	(31,089)
Receivables	3,626,799	3,455,306
Insurance operation
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amounts receivable from agents, brokers and insureds	2,870,719	2,686,199
Receivables, gross	124,258	117,436
Markel Ventures [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	638,480	657,156
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	$ 26,651	$ 25,604

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.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business.

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Carrying amount as of the balance sheet date, net of allowance for doubtful accounts, of all premiums and other types of receivables due from other persons or entities.

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