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Markel Group (Parent Company Only) Financial Information (Schedule of Condensed Balance Sheets - Parenthetical) (Details) - USD ($) $ in Thousands | Dec. 31, 2024 | Dec. 31, 2023
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Condensed Financial Statements, Captions [Line Items] |  |
Fixed maturities, amortized cost | $ 16,457,723 |
Equity securities cost | 3,887,820 | $ 3,497,071
Parent Company [Member] |  |
Condensed Financial Statements, Captions [Line Items] |  |
Fixed maturities, amortized cost | 130,983 | 139,766
Equity securities cost | $ 1,084,814 | $ 1,089,332

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