Employee Benefit Plan, Fair Value and NAV (Details) - EBP 001 [Member] - USD ($)	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Fair Value	$ 1,115,583,216	$ 973,898,628
EBP, Fair Value, Investment, NAV, Redemption, Description	Participant redemptions are generally permitted daily with no restrictions or notice period.
EBP, Fair Value, Investment, NAV, Unfunded Commitment	$ 0	0
Fair Value, Inputs, Level 1 [Member] \| Mutual funds
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Fair Value	347,446,541	625,442,877
Fair Value, Inputs, Level 1 [Member] \| Markel Group Inc. common stock
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Fair Value	245,758,017	210,533,330
Fair Value Measured at Net Asset Value [Member] \| Collective investment trusts
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Fair Value	$ 522,378,658	$ 137,922,421

Description of information about redemption of investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), that is measured at net asset value (NAV) per share as practical expedient for estimate of fair value. Includes, but is not limited, term, condition, circumstance in which otherwise redeemable investment might not be redeemable, and restriction on ability to sell investment at measurement date.

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Fair value of investment, excluding plan interest in master trust, held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Includes, but is not limited to, derivative, investment measured at net asset value per share as practical expedient, and insurance contract not meeting fully-benefit responsive investment criteria.

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