Acquisitions and Dispositions	12 Months Ended
Acquisitions and Dispositions	Dec. 31, 2023
Business combinations, Asset acquisition and Disposition [Abstract]
Acquisitions and Dispositions	Acquisitions and Dispositions Volante In October 2022, the Company sold its controlling interest in its Volante managing general agent companies (Volante) for total consideration of $181.9 million, of which $155.6 million was cash. This transaction resulted in a gain of $118.5 million that was included in services and other revenue. Volante underwrites and administers specialty insurance and reinsurance policies and provides delegated underwriting services to third-party providers of insurance capital. Velocity In February 2022, the Company sold the majority of its controlling interest in its Velocity managing general agent companies (Velocity) for total cash consideration of $181.3 million, which resulted in a gain of $107.3 million that was included in services and other revenues. The Company retained a minority interest in Velocity. In June 2023, the Company sold Independent Specialty Insurance Company (ISIC), a subsidiary within its program services operations, to Velocity. ISIC is a licensed insurance carrier, the value of which is attributed to its insurance licenses. This transaction resulted in a gain of $16.9 million and was included in services and other revenues. Velocity utilizes ISIC to provide risk origination services for the Company's Nephila insurance-linked securities fund management operations, as well as for third parties. Metromont LLC In December 2021, the Company acquired 51% of Metromont LLC (Metromont), a precast concrete manufacturer and concrete building solutions provider for commercial projects. Under the terms of the acquisition agreement, the Company has the option to acquire the remaining equity interests and the remaining equity holders have the option to sell their interests to the Company. The redemption value of the remaining equity interests is generally based on Metromont's earnings in specified periods preceding the redemption date. Total consideration for the transaction was $274.5 million, all of which was cash. The purchase price was allocated to the acquired assets and liabilities of Metromont based on estimated fair value at the acquisition date. The Company recognized goodwill of $101.6 million, intangible assets of $230.0 million and redeemable noncontrolling interests of $247.4 million. Goodwill is primarily attributable to expected future earnings and cash flow potential of Metromont, of which the Company's share is deductible for income tax purposes. Intangible assets include $175.0 million of customer relationships and $55.0 million of trade names, which are being amortized over 17 years and 15 years, respectively. Results attributable to Metromont are included in the Company's Markel Ventures segment. Buckner HeavyLift Cranes In August 2021, the Company acquired 90% of the holding company for the Buckner HeavyLift Cranes companies (Buckner), a provider of crane rental services for large commercial contractors. Under the terms of the acquisition agreement, the Company has the option to acquire the remaining equity interests and the remaining equity holders have the option to sell their interests to the Company in the future. The redemption value of the remaining equity interests is generally based on Buckner's earnings in specified periods preceding the redemption dates. Total consideration for the transaction was $237.9 million, all of which was cash. The purchase price was allocated to the acquired assets and liabilities of Buckner based on estimated fair value at the acquisition date. The Company recognized goodwill of $109.9 million, intangible assets of $60.0 million and fixed assets of $290.4 million, primarily related to cranes. Goodwill is primarily attributable to expected future earnings and cash flow potential of Buckner, and it is not deductible for income tax purposes. Intangible assets include $50.0 million of customer relationships and $10.0 million of trade names, which are being amortized over 7 years and 15 years, respectively. Additionally, the Company assumed long-term debt of $165.1 million and recognized redeemable noncontrolling interests of $26.4 million. Results attributable to Buckner are included in the Company's Markel Ventures segment.