Basis Of Presentation	9 Months Ended
Sep. 30, 2012
Basis Of Presentation [Abstract]
Basis Of Presentation	Basis of Presentation Markel Corporation is a diverse financial holding company serving a variety of niche markets. Markel Corporation’s principal business markets and underwrites specialty insurance products and programs. Markel Corporation also owns interests in various industrial and service businesses that operate outside of the specialty insurance marketplace. The consolidated balance sheet as of September 30, 2012, the related consolidated statements of income and comprehensive income (loss) for the quarters and nine months ended September 30, 2012 and 2011, and the consolidated statements of changes in equity and cash flows for the nine months ended September 30, 2012 and 2011 are unaudited. In the opinion of management, all adjustments necessary for fair presentation of such consolidated financial statements have been included. Such adjustments consist only of normal, recurring items. Interim results are not necessarily indicative of results of operations for the entire year. The consolidated balance sheet as of December 31, 2011 was derived from Markel Corporation’s audited annual consolidated financial statements. The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and include the accounts of Markel Corporation and all subsidiaries (the Company). All significant intercompany balances and transactions have been eliminated in consolidation. The Company consolidates the results of its non-insurance subsidiaries on a one-month lag. Certain prior year amounts have been reclassified to conform to the current presentation. The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results may differ materially from the estimates and assumptions used in preparing the consolidated financial statements. The consolidated financial statements and notes are presented as permitted by Form 10-Q and do not contain certain information included in the Company’s annual consolidated financial statements and notes. Readers are urged to review the Company’s 2011 Annual Report on Form 10-K for a more complete description of the Company’s business and accounting policies. ParkLand Ventures, Inc. (ParkLand), a subsidiary of the Company, has formed subsidiaries for the purpose of acquiring and financing real estate (the real estate subsidiaries). The assets of the real estate subsidiaries, which are not material to the Company, are consolidated in accordance with U.S. GAAP but are not available to satisfy the debt and other obligations of the Company or any affiliates other than the real estate subsidiaries.

Basis of Presentation

Markel Corporation is a diverse financial holding company serving a variety of niche markets. Markel Corporation’s principal business markets and underwrites specialty insurance products and programs. Markel Corporation also owns interests in various industrial and service businesses that operate outside of the specialty insurance marketplace.

The consolidated balance sheet as of September 30, 2012, the related consolidated statements of income and comprehensive income (loss) for the quarters and nine months ended September 30, 2012 and 2011, and the consolidated statements of changes in equity and cash flows for the nine months ended September 30, 2012 and 2011 are unaudited. In the opinion of management, all adjustments necessary for fair presentation of such consolidated financial statements have been included. Such adjustments consist only of normal, recurring items. Interim results are not necessarily indicative of results of operations for the entire year. The consolidated balance sheet as of December 31, 2011 was derived from Markel Corporation’s audited annual consolidated financial statements.

The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and include the accounts of Markel Corporation and all subsidiaries (the Company). All significant intercompany balances and transactions have been eliminated in consolidation. The Company consolidates the results of its non-insurance subsidiaries on a one-month lag. Certain prior year amounts have been reclassified to conform to the current presentation.

The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results may differ materially from the estimates and assumptions used in preparing the consolidated financial statements.

The consolidated financial statements and notes are presented as permitted by Form 10-Q and do not contain certain information included in the Company’s annual consolidated financial statements and notes. Readers are urged to review the Company’s 2011 Annual Report on Form 10-K for a more complete description of the Company’s business and accounting policies.

ParkLand Ventures, Inc. (ParkLand), a subsidiary of the Company, has formed subsidiaries for the purpose of acquiring and financing real estate (the real estate subsidiaries). The assets of the real estate subsidiaries, which are not material to the Company, are consolidated in accordance with U.S. GAAP but are not available to satisfy the debt and other obligations of the Company or any affiliates other than the real estate subsidiaries.