Markel (MKL) 10-Q 1 May 24 2024 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2024	Apr. 24, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-15811
Entity Registrant Name	MARKEL GROUP INC.
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	54-1959284
Entity Address, Address Line One	4521 Highwoods Parkway
Entity Address, City or Town	Glen Allen
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	23060-6148
City Area Code	804
Local Phone Number	747-0136
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	MKL
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		13,002,646
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001096343
Current Fiscal Year End Date	--12-31

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Assets [Abstract]
Fixed maturity securities, available-for-sale (amortized cost of $15,227,752 in 2024 and $14,932,286 in 2023)	$ 14,519,370	$ 14,372,732
Equity securities (cost of $3,573,927 in 2024 and $3,497,071 in 2023)	10,570,975	9,577,871
Short-term investments, available-for-sale (estimated fair value approximates cost)	2,617,642	2,571,382
Total Investments	27,707,987	26,521,985
Cash and cash equivalents	3,627,142	3,747,060
Restricted cash and cash equivalents	649,598	584,974
Receivables	3,608,947	3,455,306
Reinsurance recoverables	9,575,066	9,235,501
Deferred policy acquisition costs	961,819	931,344
Prepaid reinsurance premiums	2,783,613	2,365,243
Goodwill	2,626,258	2,624,749
Intangible assets	1,545,709	1,588,684
Other assets	4,200,246	3,990,864
Total Assets	57,286,385	55,045,710
Liabilities and Equity [Abstract]
Unpaid losses and loss adjustment expenses	24,144,955	23,483,321
Life and annuity benefits	617,266	649,054
Unearned premiums	7,153,997	6,642,426
Payables to insurance and reinsurance companies	1,237,996	1,037,722
Senior long-term debt and other debt (estimated fair value of $3,386,000 in 2024 and $3,353,000 in 2023)	3,855,494	3,779,796
Other liabilities	3,959,161	3,927,498
Total Liabilities	40,968,869	39,519,817
Redeemable noncontrolling interests	499,993	469,685
Commitments and contingencies
Shareholders' equity:
Preferred Stock	591,891	591,891
Common stock	3,547,912	3,517,146
Retained earnings	12,184,925	11,353,101
Accumulated other comprehensive loss	(595,009)	(478,210)
Total Shareholders' Equity	15,729,719	14,983,928
Noncontrolling interests	87,804	72,280
Total Equity	15,817,523	15,056,208
Total Liabilities and Equity	$ 57,286,385	$ 55,045,710

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Fixed maturities, available-for-sale, amortized cost	$ 15,227,752	$ 14,932,286
Equity securities, cost	3,573,927	3,497,071
Senior long-term debt and other debt, fair value	$ 3,386,000	$ 3,353,000

Consolidated Statements Of Inco

Consolidated Statements Of Income And Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
OPERATING REVENUES
Earned premiums	$ 2,127,627	$ 1,967,704
Net investment income	218,269	159,335
Net investment gains	902,281	372,563
Products revenues	600,840	577,926
Services and other revenues	617,638	565,861
Total Operating Revenues	4,466,655	3,643,389
OPERATING EXPENSES
Losses and loss adjustment expenses	1,287,747	1,173,014
Underwriting, acquisition and insurance expenses	738,752	675,705
Products expenses	523,247	515,756
Services and other expenses	536,838	480,619
Amortization of acquired intangible assets	44,285	44,399
Total Operating Expenses	3,130,869	2,889,493
Operating Income	1,335,786	753,896
Interest expense	(45,548)	(49,438)
Foreign exchange gains (losses)	51,500	(32,928)
Income Before Income Taxes	1,341,738	671,530
Income tax expense	(292,556)	(133,731)
Net Income	1,049,182	537,799
Net income attributable to noncontrolling interests	(23,998)	(49,147)
Net Income to Shareholders	1,025,184	488,652
Preferred stock dividends	0	0
Net Income to Common Shareholders	1,025,184	488,652
OTHER COMPREHENSIVE INCOME (LOSS)
Net holding gains (losses) arising during the period	(128,425)	161,206
Reclassification adjustments for net losses in net income	5,723	2,994
Change in net unrealized losses on available-for-sale investments, net of taxes	(122,702)	164,200
Change in discount rate for life and annuity benefits, net of taxes	6,418	(9,052)
Change in foreign currency translation adjustments, net of taxes	(475)	2,579
Change in net actuarial pension loss, net of taxes	20	18
Total Other Comprehensive Income (Loss)	(116,739)	157,745
Comprehensive Income	932,443	695,544
Comprehensive income attributable to noncontrolling interests	(24,058)	(49,179)
Comprehensive Income to Shareholders	$ 908,385	$ 646,365
NET INCOME PER COMMON SHARE
Basic	$ 75.56	$ 37.33
Diluted	$ 75.43	$ 37.26

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Equity - USD ($) $ in Thousands	Total	Total Equity [Member]	Total Shareholders' Equity [Member]	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]	Redeemable Noncontrolling Interests [Member]
Balance at Dec. 31, 2022		$ 13,213,885	$ 13,151,094	$ 591,891	$ 3,493,893	$ 9,832,804	$ (767,494)	$ 62,791
Balance, redeemable noncontrolling interests at Dec. 31, 2022									$ 523,154
Net Income	$ 537,799	533,345	488,652			488,652	0	44,693	4,454
Other comprehensive income (loss)	157,745	157,713	157,713			0	157,713	0	32
Comprehensive Income (Loss)	695,544	691,058	646,365					44,693	4,486
Repurchase of common stock		(81,964)	(81,964)	0	0	(81,964)	0	0	0
Restricted stock unit awards expensed		21,698	21,698	0	21,698	0	0	0	0
Adjustment of redeemable noncontrolling interests		13,473	13,473	0	0	13,473	0	0	(13,473)
Purchase of noncontrolling interest		(8,619)	(8,619)	0	(8,619)	0	0	0	(13,046)
Redemption of Markel CATCo Re noncontrolling interests	(88,997)	(62,646)	0	0	0	0	0	(62,646)	0
Other		2,436	2,436	0	0	2,436	0	0	(9,238)
Balance at Mar. 31, 2023		13,789,321	13,744,483	591,891	3,506,972	10,255,401	(609,781)	44,838
Balance, redeemable noncontrolling interests at Mar. 31, 2023									491,883
Balance at Dec. 31, 2023	15,056,208	15,056,208	14,983,928	591,891	3,517,146	11,353,101	(478,210)	72,280
Balance, redeemable noncontrolling interests at Dec. 31, 2023	469,685								469,685
Net Income	1,049,182	1,040,708	1,025,184			1,025,184	0	15,524	8,474
Other comprehensive income (loss)	(116,739)	(116,799)	(116,799)			0	(116,799)	0	60
Comprehensive Income (Loss)	932,443	923,909	908,385					15,524	8,534
Repurchase of common stock		(160,882)	(160,882)	0	0	(160,882)	0	0	0
Restricted stock unit awards expensed		30,766	30,766	0	30,766	0	0	0	0
Adjustment of redeemable noncontrolling interests		(32,602)	(32,602)	0	0	(32,602)	0	0	32,602
Redemption of Markel CATCo Re noncontrolling interests	0
Other		124	124	0	0	124	0	0	(10,828)
Balance at Mar. 31, 2024	15,817,523	$ 15,817,523	$ 15,729,719	$ 591,891	$ 3,547,912	$ 12,184,925	$ (595,009)	$ 87,804
Balance, redeemable noncontrolling interests at Mar. 31, 2024	$ 499,993								$ 499,993

Condensed Consolidated Statemen

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
OPERATING ACTIVITIES
Net income	$ 1,049,182	$ 537,799
Adjustments to reconcile net income to net cash provided by operating activities	(418,528)	(253,618)
Net Cash Provided By Operating Activities	630,654	284,181
INVESTING ACTIVITIES
Proceeds from sales, maturities, calls and prepayments of fixed maturity securities	546,793	592,004
Cost of fixed maturity securities purchased	(880,028)	(806,704)
Proceeds from sales of equity securities	40,101	64,030
Cost of equity securities purchased	(126,303)	(129,163)
Net change in short-term investments	(21,378)	210,177
Additions to property and equipment	(71,953)	(37,179)
Acquisitions, net of cash acquired	48,980	0
Other	(2,419)	(1,696)
Net Cash Used By Investing Activities	(564,167)	(108,531)
FINANCING ACTIVITIES
Additions to senior long-term debt and other debt	272,449	161,151
Repayment of senior long-term debt and other debt	(209,415)	(369,227)
Repurchases of common stock	(160,882)	(81,964)
Redemption of Markel CATCo Re noncontrolling interests	0	(88,997)
Purchase of noncontrolling interests	0	(21,665)
Other	(4,887)	(11,452)
Net Cash Used By Financing Activities	(102,735)	(412,154)
Effect of foreign currency rate changes on cash, cash equivalents, restricted cash and restricted cash equivalents	(19,046)	19,844
Decrease in cash, cash equivalents, restricted cash and restricted cash equivalents	(55,294)	(216,660)
Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of period	4,332,034	5,221,513
CASH, CASH EQUIVALENTS, RESTRICTED CASH AND RESTRICTED CASH EQUIVALENTS AT END OF PERIOD	$ 4,276,740	$ 5,004,853

Summary Of Significant Accounti

Summary Of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Summary Of Significant Accounting Policies	Summary of Significant Accounting Policies Markel Group Inc. (Markel Group) is a holding company comprised of a diverse group of companies and investments with specialty insurance at its core. Through its wholly owned subsidiary, Markel Ventures, Inc. (Markel Ventures), Markel Group owns controlling interests in businesses that operate in a variety of industries. See note 2 for details regarding reportable segments. a) Basis of Presentation. The consolidated balance sheet as of March 31, 2024 and the related consolidated statements of income and comprehensive income and changes in equity for the three months ended March 31, 2024 and 2023, and the condensed consolidated statements of cash flows for the three months ended March 31, 2024 and 2023 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, 2023 was derived from Markel Group's audited annual consolidated financial statements. The accompanying consolidated financial statements have been prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) and include the accounts of Markel Group and its consolidated subsidiaries, as well as variable interest entities (VIEs) that meet the requirements for consolidation (the Company). All significant intercompany balances and transactions have been eliminated in consolidation. The Company consolidates the results of its Markel Ventures subsidiaries on a one-month lag, with the exception of significant transactions or events that occur during the intervening period. Certain prior period amounts have been reclassified to conform to the current period 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. For a more complete description of the Company's business and accounting policies, readers are urged to review the Company's 2023 Annual Report on Form 10-K. b) Recent Accounting Pronouncements Accounting Standards Not Yet Adopted In November 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . The standard requires public companies to, among other things: (1) disclose, on an annual and interim basis, significant segment expenses that are regularly provided to the chief operating decision maker and included within each reported measure of segment profit or loss; (2) disclose, on an annual and interim basis, an amount for other segment expenses that are not separately disclosed as significant segment expenses and a description of its composition; (3) provide all annual disclosures about a reportable segment's profit or loss and assets currently required by Topic 280 in interim periods; and (4) disclose the title and position of the chief operating decision maker and an explanation of how the chief operating decision maker uses the reported measures of segment profit or loss in assessing segment performance and deciding how to allocate resources. ASU No. 2023-07 becomes effective for the Company in the fourth quarter of 2024 and will be applied using a retrospective approach that requires recasting of all prior periods presented. The standard only impacts required disclosures and will not impact the Company's financial position, results of operations or cash flows. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures . The standard requires public companies, on an annual basis, to provide enhanced rate reconciliation disclosures, including disclosure of specific categories and additional information for reconciling items that meet a quantitative threshold. The standard also requires public companies to, among other things, disaggregate income taxes paid by federal, state and foreign taxes. ASU No. 2023-09 becomes effective for the Company's 2025 Annual Report on Form 10-K. The standard only impacts required disclosures and will not impact the Company's financial position, results of operations or cash flows.

Segment Reporting Disclosures

Segment Reporting Disclosures	3 Months Ended
	Mar. 31, 2024
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Segment Reporting Disclosures	Segment Reporting Disclosures The Company has four reportable segments: Insurance, Reinsurance, Investing and Markel Ventures. The chief operating decision maker reviews the Company's ongoing underwriting operations on a global basis in the following two segments: Insurance and Reinsurance. The Insurance segment includes all direct business and facultative reinsurance placements written on a risk-bearing basis within the Company's underwriting operations. The Reinsurance segment includes all treaty reinsurance written on a risk-bearing basis within the Company's underwriting operations. The Company's other insurance operations primarily consist of the results of the Company's program services and other fronting business and insurance-linked securities operations. Other insurance operations also include results for lines of business discontinued prior to, or in conjunction with, acquisitions, including development on asbestos and environmental loss reserves and results attributable to the run-off of life and annuity reinsurance business, which are monitored separately from the Company's ongoing underwriting operations. For purposes of segment reporting, none of these other insurance operations are considered to be reportable segments. The Company's Investing segment includes all investing activities related to the Company's insurance operations, as well as investing activities at Markel Group. Invested assets managed through our Investing segment include our portfolio of publicly traded fixed maturity and equity securities, as well as cash and short-term investments. The Markel Ventures segment primarily consists of controlling interests in a diverse portfolio of businesses that operate in various industries. The Company's chief operating decision maker reviews and assesses Markel Ventures' performance in the aggregate, as a single operating segment. Segment profit for all of the Company's segments is measured by operating income. Segment operating income excludes amortization of intangible assets arising from purchase accounting for acquisitions, which the chief operating decision maker does not consider in assessing the financial performance of, or allocating resources to, operating segments. Amortization of acquired intangible assets is considered a corporate expense because it is not a cost of operating the underlying businesses. For our Insurance and Reinsurance segments, segment operating income is typically consistent with underwriting profit, which the property and casualty insurance industry commonly defines as earned premiums net of losses and loss adjustment expenses and underwriting, acquisition and insurance expenses. Segment operating income for these two segments may also include other revenues and expenses that are not captured in underwriting profit. Prior to 2024, the segment profitability metric for the Markel Ventures segment included amortization of acquired intangible assets. The new metric, as previously described, better aligns with how the chief operating decision maker reviews and assesses the performance of the Markel Ventures segment. Prior periods have been recast to conform to the current presentation. Management continues to evaluate the Company's segments as its business evolves and may further refine its segments and segment profitability metric. For management reporting purposes, the Company allocates assets to its underwriting operations and to its Investing and Markel Ventures segments and certain of its other insurance operations, including its program services and other fronting business and insurance-linked securities business. Underwriting assets include assets attributed to the Company's Insurance and Reinsurance segments, discontinued underwriting lines of business, as well as assets that are not specifically allocated to the Company's other insurance operations. Generally, the Company manages its underwriting assets in the aggregate and therefore does not allocate assets to individual underwriting segments. a) The following tables summarize the Company's segment disclosures. Three Months Ended March 31, 2024 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures Other insurance operations Corporate Consolidated Earned premiums $ 1,874,461 $ 253,339 $ — $ — $ (173) $ — $ 2,127,627 Net investment income — — 217,204 1,065 — — 218,269 Net investment gains — — 902,281 — — — 902,281 Products revenues — — — 600,840 — — 600,840 Services and other revenues — — 20,846 538,701 58,091 — 617,638 Total operating revenues 1,874,461 253,339 1,140,331 1,140,606 57,918 — 4,466,655 Losses and loss adjustment expenses: Current accident year (1,201,555) (163,215) — — — — (1,364,770) Prior accident years 97,181 (3,398) — — (16,760) — 77,023 Underwriting, acquisition and insurance expenses: Amortization of policy acquisition costs (373,778) (60,809) — — — — (434,587) Other underwriting expenses (288,999) (13,907) — — (1,259) — (304,165) Products expenses — — — (523,247) — — (523,247) Services and other expenses — — — (513,444) (23,394) — (536,838) Amortization of acquired intangible assets (44,285) (44,285) Operating income $ 107,310 $ 12,010 $ 1,140,331 $ 103,915 $ 16,505 $ (44,285) $ 1,335,786 Interest expense (45,548) Net foreign exchange gains 51,500 Income before income taxes $ 1,341,738 Three Months Ended March 31, 2023 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures Other insurance operations Corporate Consolidated Earned premiums $ 1,710,924 $ 257,234 $ — $ — $ (454) $ — $ 1,967,704 Net investment income — — 158,594 741 — — 159,335 Net investment gains — — 372,563 — — — 372,563 Products revenues — — — 577,926 — — 577,926 Services and other revenues — — (2,380) 526,013 42,228 — 565,861 Total operating revenues 1,710,924 257,234 528,777 1,104,680 41,774 — 3,643,389 Losses and loss adjustment expenses: Current accident year (1,077,546) (166,785) — — — — (1,244,331) Prior accident years 62,628 8,704 — — (15) — 71,317 Underwriting, acquisition and insurance expenses: Amortization of policy acquisition costs (360,354) (61,778) — — — — (422,132) Other underwriting expenses (239,148) (13,141) — — (1,284) — (253,573) Products expenses — — — (515,756) — — (515,756) Services and other expenses — — — (496,746) 16,127 — (480,619) Amortization of acquired intangible assets (44,399) (44,399) Operating income $ 96,504 $ 24,234 $ 528,777 $ 92,178 $ 56,602 $ (44,399) $ 753,896 Interest expense (49,438) Net foreign exchange losses (32,928) Income before income taxes $ 671,530 b) The following table reconciles segment assets to the Company's consolidated balance sheets. (dollars in thousands) March 31, 2024 December 31, 2023 Segment assets: Investing $ 31,699,863 $ 30,542,282 Underwriting 10,317,034 9,897,689 Markel Ventures 5,623,756 5,519,542 Total segment assets 47,640,653 45,959,513 Other insurance operations 9,645,732 9,086,197 Total assets $ 57,286,385 $ 55,045,710

Investments

Investments	3 Months Ended
	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Investments	Investments a) The following tables summarize the Company's available-for-sale investments. Commercial and residential mortgage-backed securities include securities issued by U.S. government-sponsored enterprises and U.S. government agencies. The net unrealized holding gains (losses) in the tables below are presented before taxes. March 31, 2024 (dollars in thousands) Amortized Gross Gross Estimated Fixed maturity securities: U.S. Treasury securities $ 4,113,319 $ 12,079 $ (79,408) $ 4,045,990 U.S. government-sponsored enterprises 1,289,119 4,206 (99,430) 1,193,895 Obligations of states, municipalities and political subdivisions 4,041,845 10,059 (205,316) 3,846,588 Foreign governments 1,950,839 4,132 (126,930) 1,828,041 Commercial mortgage-backed securities 2,400,848 4,780 (137,472) 2,268,156 Residential mortgage-backed securities 463,710 155 (22,187) 441,678 Corporate bonds 968,072 5,424 (78,474) 895,022 Total fixed maturity securities 15,227,752 40,835 (749,217) 14,519,370 Short-term investments 2,618,162 597 (1,117) 2,617,642 Investments, available-for-sale $ 17,845,914 $ 41,432 $ (750,334) $ 17,137,012 December 31, 2023 (dollars in thousands) Amortized Gross Gross Estimated Fixed maturity securities: U.S. Treasury securities $ 3,811,293 $ 35,824 $ (62,404) $ 3,784,713 U.S. government-sponsored enterprises 1,225,426 7,292 (89,904) 1,142,814 Obligations of states, municipalities and political subdivisions 4,196,096 14,787 (181,578) 4,029,305 Foreign governments 1,858,845 21,450 (96,874) 1,783,421 Commercial mortgage-backed securities 2,371,406 8,605 (136,353) 2,243,658 Residential mortgage-backed securities 491,949 334 (21,861) 470,422 Corporate bonds 977,271 13,043 (71,915) 918,399 Total fixed maturity securities 14,932,286 101,335 (660,889) 14,372,732 Short-term investments 2,564,620 7,155 (393) 2,571,382 Investments, available-for-sale $ 17,496,906 $ 108,490 $ (661,282) $ 16,944,114 b) The following tables summarize gross unrealized investment losses on available-for-sale investments by the length of time that securities have continuously been in an unrealized loss position. Unrealized losses on available-for-sale investments are typically the result of declines in the fair value of the investments due to increases in interest rates. March 31, 2024 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Gross Estimated Gross Estimated Gross Fixed maturity securities: U.S. Treasury securities $ 1,553,613 $ (10,383) $ 1,388,322 $ (69,025) $ 2,941,935 $ (79,408) U.S. government-sponsored enterprises 244,720 (3,629) 746,832 (95,801) 991,552 (99,430) Obligations of states, municipalities and political subdivisions 920,869 (8,138) 2,376,770 (197,178) 3,297,639 (205,316) Foreign governments 322,098 (3,059) 1,079,889 (123,871) 1,401,987 (126,930) Commercial mortgage-backed securities 275,805 (4,101) 1,722,270 (133,371) 1,998,075 (137,472) Residential mortgage-backed securities 25,905 (456) 401,845 (21,731) 427,750 (22,187) Corporate bonds 148,340 (2,336) 574,746 (76,138) 723,086 (78,474) Total fixed maturity securities 3,491,350 (32,102) 8,290,674 (717,115) 11,782,024 (749,217) Short-term investments 2,272,608 (1,117) — — 2,272,608 (1,117) Total $ 5,763,958 $ (33,219) $ 8,290,674 $ (717,115) $ 14,054,632 $ (750,334) At March 31, 2024, the Company held 1,578 available-for-sale securities in an unrealized loss position with a total estimated fair value of $14.1 billion and gross unrealized losses of $750.3 million. Of these 1,578 securities, 1,126 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $8.3 billion and gross unrealized losses of $717.1 million. December 31, 2023 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Gross Estimated Gross Estimated Gross Fixed maturity securities: U.S. Treasury securities $ 317,027 $ (2,147) $ 1,507,784 $ (60,257) $ 1,824,811 $ (62,404) U.S. government-sponsored enterprises 145,143 (2,134) 723,537 (87,770) 868,680 (89,904) Obligations of states, municipalities and political subdivisions 679,124 (3,881) 2,332,281 (177,697) 3,011,405 (181,578) Foreign governments 49,056 (128) 1,113,616 (96,746) 1,162,672 (96,874) Commercial mortgage-backed securities 169,557 (1,792) 1,790,637 (134,561) 1,960,194 (136,353) Residential mortgage-backed securities 20,420 (80) 431,705 (21,781) 452,125 (21,861) Corporate bonds 34,340 (266) 615,501 (71,649) 649,841 (71,915) Total fixed maturity securities 1,414,667 (10,428) 8,515,061 (650,461) 9,929,728 (660,889) Short-term investments 52,601 (393) — — 52,601 (393) Total $ 1,467,268 $ (10,821) $ 8,515,061 $ (650,461) $ 9,982,329 $ (661,282) At December 31, 2023, the Company held 1,386 available-for-sale securities in an unrealized loss position with a total estimated fair value of $10.0 billion and gross unrealized losses of $661.3 million. Of these 1,386 securities, 1,131 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $8.5 billion and gross unrealized losses of $650.5 million. The Company completes a detailed analysis each quarter to assess whether the decline in the fair value of any investment below its cost basis is the result of a credit loss. All available-for-sale securities with unrealized losses are reviewed. The Company considers many factors in completing its quarterly review of securities with unrealized losses for credit-related impairment to determine whether a credit loss exists, including the extent to which fair value is below cost, the implied yield to maturity, rating downgrades of the security and whether or not the issuer has failed to make scheduled principal or interest payments. The Company also takes into consideration information about the financial condition of the issuer and industry factors that could negatively impact the issuer. If the decline in fair value of an available-for-sale security below its amortized cost is considered to be the result of a credit loss, the Company compares the estimated present value of the cash flows expected to be collected to the amortized cost of the security. The extent to which the estimated present value of the cash flows expected to be collected is less than the amortized cost of the security represents the credit loss, which is recorded as an allowance and recognized in net income. The allowance is limited to the difference between the fair value and the amortized cost of the security. Any remaining decline in fair value represents the non-credit portion of the impairment, which is recognized in other comprehensive income. The Company did not have an allowance for credit losses for any available-for-sale securities as of March 31, 2024 or December 31, 2023. Quarterly, the Company also considers whether it intends to sell an available-for-sale security or if it is more likely than not that it will be required to sell a security before recovery of its amortized cost. In these instances, a decline in fair value is recognized in net income based on the fair value of the security at the time of assessment, resulting in a new cost basis for the security. c) The amortized cost and estimated fair value of fixed maturity securities at March 31, 2024 are shown below by contractual maturity. (dollars in thousands) Amortized Estimated Due in one year or less $ 1,108,711 $ 1,091,274 Due after one year through five years 5,268,266 5,082,020 Due after five years through ten years 4,482,619 4,278,074 Due after ten years 1,503,598 1,358,168 12,363,194 11,809,536 Commercial mortgage-backed securities 2,400,848 2,268,156 Residential mortgage-backed securities 463,710 441,678 Total fixed maturity securities $ 15,227,752 $ 14,519,370 d) The following table presents the components of net investment income. Three Months Ended March 31, (dollars in thousands) 2024 2023 Interest: Fixed maturity securities $ 119,476 $ 82,128 Short-term investments 32,184 26,619 Cash and cash equivalents and restricted cash and cash equivalents 39,078 27,601 Dividends on equity securities 32,693 27,482 223,431 163,830 Investment expenses (5,162) (4,495) Net investment income $ 218,269 $ 159,335 e) The following table presents the components of net investment gains included in net income and the change in net unrealized losses included in other comprehensive income (loss). Gross realized investment gains and losses on fixed maturity securities, short-term investments and other investments were not material to the consolidated financial statements and are presented on a net basis in the following table. Three Months Ended March 31, (dollars in thousands) 2024 2023 Fixed maturity securities, short-term investments and other investments: Net realized investment losses $ (4,488) $ (3,221) Equity securities: Change in fair value of securities sold during the period 43 5,637 Change in fair value of securities held at the end of the period 906,726 370,147 Total change in fair value 906,769 375,784 Net investment gains $ 902,281 $ 372,563 Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss): Fixed maturity securities $ (148,487) $ 209,179 Short-term investments (7,282) (810) Net increase (decrease) $ (155,769) $ 208,369

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements FASB ASC 820, Fair Value Measurements and Disclosures, establishes a three-level hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). If the inputs used to measure the assets or liabilities fall within different levels of the hierarchy, the classification is based on the lowest level input that is significant to the fair value measurement of the asset or liability. Classification of assets and liabilities within the hierarchy considers the markets in which the assets and liabilities are traded and the reliability and transparency of the assumptions used to determine fair value. The hierarchy requires the use of observable market data when available. The levels of the hierarchy are defined as follows: • Level 1 – Inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities traded in active markets. • Level 2 – Inputs to the valuation methodology include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability and market-corroborated inputs. • Level 3 – Inputs to the valuation methodology are unobservable for the asset or liability and are significant to the fair value measurement. In accordance with ASC 820, the Company determines fair value based on the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. In determining fair value, the Company uses various methods, including the market, income and cost approaches. The Company uses valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. The following section describes the valuation methodologies used by the Company to measure assets and liabilities at fair value, including an indication of the level within the fair value hierarchy in which each asset or liability is generally classified. Available-for-sale investments and equity securities. Available-for-sale investments and equity securities are recorded at fair value on a recurring basis. Available-for-sale investments include fixed maturity securities and short-term investments. Fair value is determined by the Company after considering various sources of information, including information provided by a third-party pricing service. The pricing service provides prices for substantially all of the Company's fixed maturity securities and equity securities. In determining fair value, the Company generally does not adjust the prices obtained from the pricing service. The Company obtains an understanding of the pricing service's valuation methodologies and related inputs, which include, but are not limited to, reported trades, benchmark yields, issuer spreads, bids, offers, duration, credit ratings, estimated cash flows and prepayment speeds. The Company validates prices provided by the pricing service by reviewing prices from other pricing sources and analyzing pricing data in certain instances. The Company has evaluated the various types of securities in its investment portfolio to determine an appropriate fair value hierarchy level based upon trading activity and the observability of market inputs. Level 1 investments include those traded on an active exchange, such as the New York Stock Exchange. Level 2 investments include U.S. Treasury securities, U.S. government-sponsored enterprises, municipal bonds, foreign government bonds, commercial mortgage-backed securities, residential mortgage-backed securities and corporate debt securities. Level 3 investments include the Company's investments in insurance-linked securities funds that are in run-off, which are not traded on an active exchange and are valued using unobservable inputs. Fair value for available-for-sale investments and equity securities is measured based upon quoted prices in active markets, if available. Due to variations in trading volumes and the lack of quoted market prices, fixed maturity securities are classified as Level 2 investments. The fair value of fixed maturity securities is normally derived through recent reported trades for identical or similar securities, making adjustments through the reporting date based upon available market observable data previously described. If there are no recent reported trades, the fair value of fixed maturity securities may be derived through the use of matrix pricing or model processes, where future cash flow expectations are developed based upon collateral performance and discounted at an estimated market rate. Significant inputs used to determine the fair value of obligations of states, municipalities and political subdivisions, corporate bonds and obligations of foreign governments include reported trades, benchmark yields, issuer spreads, bids, offers, credit information and estimated cash flows. Significant inputs used to determine the fair value of commercial mortgage-backed securities and residential mortgage-backed securities include the type of underlying assets, benchmark yields, prepayment speeds, collateral information, tranche type and volatility, estimated cash flows, credit information, default rates, recovery rates, issuer spreads and the year of issue. Senior long-term debt and other debt. Senior long-term debt and other debt is carried at amortized cost with the estimated fair value disclosed on the consolidated balance sheets. Senior long-term debt and other debt is classified as Level 2 within the fair value hierarchy due to variations in trading volumes and the lack of quoted market prices. Fair value is generally derived through recent reported trades, making adjustments through the reporting date, if necessary, based upon available market observable data including U.S. Treasury securities and implied credit spreads. Significant inputs used to determine the fair value of senior long-term debt and other debt include reported trades, benchmark yields, issuer spreads, bids and offers. The following tables present the balances of assets measured at fair value on a recurring basis by level within the fair value hierarchy. March 31, 2024 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments: Fixed maturity securities, available-for-sale: U.S. Treasury securities $ — $ 4,045,990 $ — $ 4,045,990 U.S. government-sponsored enterprises — 1,193,895 — 1,193,895 Obligations of states, municipalities and political subdivisions — 3,846,588 — 3,846,588 Foreign governments — 1,828,041 — 1,828,041 Commercial mortgage-backed securities — 2,268,156 — 2,268,156 Residential mortgage-backed securities — 441,678 — 441,678 Corporate bonds — 895,022 — 895,022 Total fixed maturity securities, available-for-sale — 14,519,370 — 14,519,370 Equity securities: Insurance, banks and other financial institutions 4,177,578 — 1,157 4,178,735 Industrial, consumer and all other 6,392,240 — — 6,392,240 Total equity securities 10,569,818 — 1,157 10,570,975 Short-term investments, available-for-sale 2,453,881 163,761 — 2,617,642 Total investments $ 13,023,699 $ 14,683,131 $ 1,157 $ 27,707,987 December 31, 2023 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments: Fixed maturity securities, available-for-sale: U.S. Treasury securities $ — $ 3,784,713 $ — $ 3,784,713 U.S. government-sponsored enterprises — 1,142,814 — 1,142,814 Obligations of states, municipalities and political subdivisions — 4,029,305 — 4,029,305 Foreign governments — 1,783,421 — 1,783,421 Commercial mortgage-backed securities — 2,243,658 — 2,243,658 Residential mortgage-backed securities — 470,422 — 470,422 Corporate bonds — 918,399 — 918,399 Total fixed maturity securities, available-for-sale — 14,372,732 — 14,372,732 Equity securities: Insurance, banks and other financial institutions 3,694,375 — 994 3,695,369 Industrial, consumer and all other 5,882,502 — — 5,882,502 Total equity securities 9,576,877 — 994 9,577,871 Short-term investments, available-for-sale 2,402,099 169,283 — 2,571,382 Total investments $ 11,978,976 $ 14,542,015 $ 994 $ 26,521,985 The Company did not have any assets or liabilities measured at fair value on a non-recurring basis during the three months ended March 31, 2024 and 2023.

Equity Method Investments

Equity Method Investments	3 Months Ended
	Mar. 31, 2024
Equity Method Investments [Abstract]
Equity Method Investments Disclosure [Text Block]	Equity Method Investments The Company's equity method investments, which are included in other assets on the consolidated balance sheets, totaled $633.6 million and $605.9 million as of March 31, 2024 and December 31, 2023, respectively. The Company's proportionate share of earnings in its equity method investments was income of $25.9 million and a loss of $1.5 million for three months ended March 31, 2024 and 2023, respectively. The Company's most significant equity method investment is an investment in Hagerty, Inc. (Hagerty), which is accounted for on a quarter lag. Hagerty is an automotive enthusiast brand offering integrated membership products and programs as well as a specialty insurance provider focused on the global automobile enthusiast market. The Company's ownership interest in Hagerty was 23% as of March 31, 2024 and December 31, 2023. The Company's investment is comprised of Class A common shares, which are listed for trading on the New York Stock Exchange, as well as Class V common shares, associated with the Company's original investment, that have special voting rights and can be converted on a one-for-one basis into Class A common shares. The Company accounts for its investment under the equity method as it is deemed to have the ability to exercise significant influence over Hagerty's operating and financial policies through a combination of its voting interest, its right to designate a board member and business it conducts with Hagerty. As of March 31, 2024 and December 31, 2023, the carrying value of the Company's investment in Hagerty was $238.4 million and $237.4 million, respectively. As of March 31, 2024 and December 31, 2023, the estimated value of the Company's investment, based on the closing stock price of Hagerty's Class A common shares, was $713.7 million and $608.4 million, respectively. See note 11 for further details regarding related party transactions with Hagerty.

Products, Services and Other Re

Products, Services and Other Revenues	3 Months Ended
	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Products, Services and Other Revenues	Products, Services, and Other Revenues The following tables present revenues from contracts with customers by type, all of which are included in products revenues and services and other revenues, along with a reconciliation to total products revenues and services and other revenues. Three Months Ended March 31, 2024 2023 (dollars in thousands) Markel Ventures Other Total Markel Ventures Other Total Products $ 594,592 $ — $ 594,592 $ 565,895 $ — $ 565,895 Services 498,290 2,133 500,423 486,481 2,854 489,335 Investment management — 19,936 19,936 — 10,459 10,459 Total revenues from contracts with customers 1,092,882 22,069 1,114,951 1,052,376 13,313 1,065,689 Leasing revenues 40,753 — 40,753 41,752 — 41,752 Program services and other fronting fees — 36,030 36,030 — 28,890 28,890 Equity method and other investments income (loss) 5,179 20,846 26,025 1,495 (2,380) (885) Other 727 (8) 719 8,316 25 8,341 Total $ 1,139,541 $ 78,937 $ 1,218,478 $ 1,103,939 $ 39,848 $ 1,143,787 Receivables from contracts with customers were $537.6 million and $616.4 million as of March 31, 2024 and December 31, 2023, respectively.

Unpaid Losses And Loss Adjustme

Unpaid Losses And Loss Adjustment Expenses	3 Months Ended
	Mar. 31, 2024
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Unpaid Losses And Loss Adjustment Expenses	Unpaid Losses and Loss Adjustment Expenses The following table presents a reconciliation of consolidated beginning and ending reserves for losses and loss adjustment expenses. Three Months Ended March 31, (dollars in thousands) 2024 2023 Gross reserves for losses and loss adjustment expenses, beginning of year $ 23,483,321 $ 20,947,898 Reinsurance recoverables on unpaid losses, beginning of year 8,820,567 7,994,884 Net reserves for losses and loss adjustment expenses, beginning of year 14,662,754 12,953,014 Effect of foreign currency rate changes on beginning of year balance (33,620) 36,637 Adjusted net reserves for losses and loss adjustment expenses, beginning of year 14,629,134 12,989,651 Incurred losses and loss adjustment expenses: Current accident year 1,364,770 1,244,331 Prior accident years (77,023) (71,317) Total incurred losses and loss adjustment expenses 1,287,747 1,173,014 Payments: Current accident year 75,509 72,167 Prior accident years 819,185 708,115 Total payments 894,694 780,282 Effect of foreign currency rate changes on current year activity (1,018) (3,649) Change in net reserves for losses and loss adjustment expenses of Markel CATCo Re (see note 10) (16,338) (115,141) Reinsurance recoverable for retroactive reinsurance transaction — (125,067) Net reserves for losses and loss adjustment expenses, end of period 15,004,831 13,138,526 Reinsurance recoverables on unpaid losses 9,140,124 8,168,267 Gross reserves for losses and loss adjustment expenses, end of period $ 24,144,955 $ 21,306,793 For the three months ended March 31, 2024, prior accident years losses and loss adjustment expenses included $77.0 million of favorable development on prior years loss reserves, which included $64.8 million of favorable development on the Company's international professional liability and marine and energy product lines within its Insurance segment. For the three months ended March 31, 2023, prior accident years losses and loss adjustment expenses included $71.3 million of favorable development on prior years loss reserves, which included $63.8 million of favorable development on the Company's marine and energy, property, workers' compensation and programs product lines within its Insurance segment. In March 2023, the Company completed a retroactive reinsurance transaction to cede its portfolio of policies comprised of liabilities for its run-off book of United Kingdom motor casualty business in exchange for payments totaling $125.1 million, which approximated the carrying value of the Company's reserves for losses and loss adjustment expenses on the ceded policies.

Reinsurance

Reinsurance	3 Months Ended
	Mar. 31, 2024
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance The following tables summarize the effect of reinsurance and retrocessional reinsurance on premiums written and earned. Three Months Ended March 31, 2024 2023 (dollars in thousands) Direct Assumed Ceded Net Premiums Direct Assumed Ceded Net Premiums Underwriting: Written $ 2,107,467 $ 668,699 $ (543,956) $ 2,232,210 $ 1,969,363 $ 688,895 $ (440,029) $ 2,218,229 Earned $ 2,198,238 $ 392,942 $ (463,380) $ 2,127,800 $ 1,971,876 $ 398,719 $ (402,440) $ 1,968,155 Program services and other fronting: Written 744,958 419,275 (1,164,406) (173) 573,211 204,543 (778,205) (451) Earned 703,682 123,271 (827,126) (173) 641,113 74,717 (716,281) (451) Consolidated: Written $ 2,852,425 $ 1,087,974 $ (1,708,362) $ 2,232,037 $ 2,542,574 $ 893,438 $ (1,218,234) $ 2,217,778 Earned $ 2,901,920 $ 516,213 $ (1,290,506) $ 2,127,627 $ 2,612,989 $ 473,436 $ (1,118,721) $ 1,967,704 Substantially all of the premiums written and earned in the Company's program services and other fronting operations for the three months ended March 31, 2024 and 2023 were ceded. The percentage of consolidated ceded earned premiums to gross earned premiums was 38% and 36% for the three months ended March 31, 2024 and 2023, respectively. The percentage of consolidated assumed earned premiums to net earned premiums was 24% for both the three months ended March 31, 2024 and 2023. Substantially all of the incurred losses and loss adjustment expenses in the Company's program services and other fronting operations were ceded. These gross losses totaled $603.7 million and $496.6 million for the three months ended March 31, 2024 and 2023, respectively. The following table summarizes the effect of reinsurance and retrocessional reinsurance on losses and loss adjustment expenses in the Company's underwriting operations. Three Months Ended March 31, (dollars in thousands) 2024 2023 Gross losses and loss adjustment expenses $ 1,693,847 $ 1,392,348 Ceded losses and loss adjustment expenses (406,167) (219,255) Net losses and loss adjustment expenses $ 1,287,680 $ 1,173,093

Life and Annuity Benefits

Life and Annuity Benefits	3 Months Ended
	Mar. 31, 2024
Liability for Future Policy Benefit, before Reinsurance [Abstract]
Life and Annuity Benefits	Life and Annuity Benefits The Company's run-off block of life and annuity reinsurance contracts consists primarily of Euro and U.S. Dollar denominated life-contingent payout annuities and traditional and universal life contracts. The following table presents the components of the Company's liabilities for life and annuity benefits. (dollars in thousands) March 31, 2024 December 31, 2023 Liability for future policyholder benefits $ 528,249 $ 557,763 Deferred profit liability 50,483 52,287 Other 38,534 39,004 Total $ 617,266 $ 649,054 The primary component of the Company's liabilities for life and annuity benefits is the liability for future policyholder benefits. Life and annuity benefit reserves are calculated for aggregated cohorts of contracts, which are determined based on the attributes of the underlying contracts, and are discounted using standard actuarial techniques and cash flow models. Since the development of the life and annuity reinsurance reserves is based upon cash flow projection models, the Company makes estimates and assumptions based on cedent experience and industry mortality tables. The cash flow assumptions used to determine the Company's life and annuity benefit reserves are reviewed, and updated as necessary, at least annually. The discount rate assumptions are updated at each reporting date. The following table presents a rollforward of the present value of the liability for future policyholder benefits. Three Months Ended March 31, (dollars in thousands) 2024 2023 Liability for future policyholder benefits, beginning of year $ 557,763 $ 554,366 Liability for future policyholder benefits at original discount rate, beginning of year 642,877 667,761 Effect of changes in cash flow assumptions — — Effect of actual variances from expected experience — — Adjusted liability for future policyholder benefits, beginning of year 642,877 667,761 Interest accretion 3,605 3,815 Benefit payments (13,290) (13,283) Effect of foreign currency rate changes (11,706) 10,396 Liability for future policyholder benefits at original discount rate, end of period 621,486 668,689 Cumulative effect of changes in discount rate assumptions (93,237) (101,938) Liability for future policyholder benefits, end of period (1) $ 528,249 $ 566,751 (1) The undiscounted liability for future policyholder benefits was $796.8 million and $862.7 million as of March 31, 2024 and 2023, respectively. The following table summarizes additional details for the Company's liability for future policyholder benefits. March 31, 2024 December 31, 2023 Weighted-average interest rate: Interest accretion rate 2.3 % 2.3 % Current discount rate 4.1 % 3.8 % Weighted-average liability duration 8.4 years 8.6 years

Variable Interest Entities

Variable Interest Entities	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	Variable Interest Entities Markel CATCo Investment Management Ltd. (MCIM), a wholly-owned consolidated subsidiary of the Company, is an insurance-linked securities investment fund manager and reinsurance manager headquartered in Bermuda. Results attributable to MCIM are not included in a reportable segment. MCIM serves as the insurance manager for Markel CATCo Re Ltd. (Markel CATCo Re), a Bermuda Class 3 reinsurance company, and as the investment manager for Markel CATCo Reinsurance Fund Ltd., a Bermuda exempted mutual fund company comprised of multiple segregated accounts (Markel CATCo Funds). Voting shares in Markel CATCo Reinsurance Fund Ltd. and Markel CATCo Re are held by MCIM, which has the power to direct the activities that most significantly impact the economic performance of these entities. The Markel CATCo Funds issued multiple classes of nonvoting, redeemable preference shares to investors, and the Markel CATCo Funds are primarily invested in nonvoting preference shares of Markel CATCo Re. The underwriting results of Markel CATCo Re are attributed to investors through its nonvoting preference shares. Both Markel CATCo Re and the Markel CATCo Funds were placed into run-off in July 2019. In 2022, the Company completed a buy-out transaction with Markel CATCo Re and the Markel CATCo Funds that provided for an accelerated return of all remaining capital to investors in the Markel CATCo Funds. Under the terms of the transaction, the Company provided cash funding of $45.1 million to purchase substantially all of the Markel CATCo Funds' interests in Markel CATCo Re. As part of the transaction, substantially all of the preference shares held by investors in the Markel CATCo Funds were redeemed, including preference shares previously held by the Company. The Company has received a return of $24.9 million of the initial cash funding provided, and the related preference shares were redeemed. As of March 31, 2024 and December 31, 2023, the Company's investment in the remaining preference shares of Markel CATCo Re totaled $20.1 million, which comprised 18% and 23%, respectively, of the equity of Markel CATCo Re. Through that investment, the Company has exposure to adverse loss development on reinsurance contracts previously written by Markel CATCo Re for loss events that occurred from 2014 to 2020. If loss reserves held by Markel CATCo Re are sufficient to settle claims on the remaining open contracts, the Company will receive a full return of the remaining $20.1 million in capital. Favorable development on loss reserves held by Markel CATCo Re, less operating expenses, will be distributed to the Markel CATCo Funds, and ultimately to investors in the Markel CATCo Funds. Markel CATCo Re is considered a VIE, as the equity at risk does not have the right to receive residual returns that exceed the capital provided by the Company in the buy-out transaction. As a result of the preference shares acquired by the Company in the buy-out transaction, and the voting shares held by its consolidated subsidiary, MCIM, the Company consolidates Markel CATCo Re as its primary beneficiary. Results attributed to the run-off of Markel CATCo Re are reported with the Company's other insurance operations, within services and other revenues and expenses, and are not included in a reportable segment. For the three months ended March 31, 2024 and 2023, there was $15.7 million and $44.8 million, respectively, of favorable loss reserve development on the run-off of reinsurance contracts written by Markel CATCo Re, all of which was included in services and other expenses and attributable to noncontrolling interests. During the three months ended March 31, 2023, $62.6 million of preference shares of Markel CATCo Re held by noncontrolling interests were redeemed. The Company's consolidated balance sheets include the following amounts attributable to Markel CATCo Re. (dollars in thousands) March 31, 2024 December 31, 2023 Assets Cash and cash equivalents $ 96,252 $ 91,301 Restricted cash and cash equivalents 169,280 173,800 Other assets and receivables due from cedents 18,742 19,292 Total Assets $ 284,274 $ 284,393 Liabilities and Equity Unpaid losses and loss adjustment expenses $ 168,630 $ 184,967 Other liabilities 2,380 1,842 Total Liabilities 171,010 186,809 Shareholders' equity 21,139 21,139 Noncontrolling interests 92,125 76,445 Total Equity 113,264 97,584 Total Liabilities and Equity $ 284,274 $ 284,393 In connection with the buy-out transaction, the Company also entered into a tail risk cover with Markel CATCo Re to allow for the release of collateral to investors. Through this contract, the Company has $95.0 million of uncollateralized exposure to adverse development on loss reserves held by Markel CATCo Re for loss exposures in excess of limits that the Company believes are unlikely to be exceeded.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2024
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	Related Party Transactions The Company engages in certain related party transactions in the normal course of business at arm's length. Insurance-Linked Securities Within the Company's insurance-linked securities operations, the Company provides investment and insurance management services through Nephila Holdings Ltd. (together with its subsidiaries, Nephila). Nephila serves as the investment manager to several Bermuda based private funds (the Nephila Funds). To provide access for the Nephila Funds to a variety of insurance-linked securities in the property catastrophe, climate and specialty markets, Nephila also acts as an insurance manager to certain Bermuda Class 3 and 3A reinsurance companies, Lloyd's Syndicate 2357 and Lloyd's Syndicate 2358 (collectively, the Nephila Reinsurers). Nephila receives management fees for investment and insurance management services provided through its insurance-linked securities operations, and, for certain funds, incentive fees based on their annual performance. For the three months ended March 31, 2024 and 2023, total revenues attributed to unconsolidated entities managed by Nephila were $19.2 million and $9.8 million, respectively. Through the Company's program services and other fronting operations, the Company has programs with Nephila through which the Company writes insurance policies that are fully ceded to the Nephila Reinsurers. Through these programs, Nephila utilizes certain of the Company's licensed insurance companies to write U.S. catastrophe-exposed property and specialty risks that are then ceded to the Nephila Reinsurers. For the three months ended March 31, 2024 and 2023, gross premiums written through the Company's program services and other fronting platforms on behalf of Nephila were $353.1 million and $236.9 million, respectively, all of which were ceded to the Nephila Reinsurers. As of March 31, 2024 and December 31, 2023, reinsurance recoverables on the consolidated balance sheets included $785.9 million and $794.3 million, respectively, due from the Nephila Reinsurers. Under its programs with the Nephila Reinsurers, the Company bears underwriting risk for annual aggregate agreement year losses in excess of a limit the Company believes is unlikely to be exceeded. To the extent losses under these programs exceed the prescribed limits, the Company is obligated to pay such losses to the cedents without recourse to the Nephila Reinsurers. While the Company believes losses under these programs are unlikely, those losses, if incurred, could be material to the Company's consolidated results of operations and financial condition. The Company has also entered into other assumed and ceded reinsurance transactions with the Nephila Reinsurers in the normal course of business, which are not material to the Company's consolidated financial statements. Hagerty The Company holds a minority ownership interest in Hagerty, which operates primarily as a managing general agent and also includes Hagerty Reinsurance Limited (Hagerty Re), a Bermuda Class 3 reinsurance company. Through the Company's underwriting operations, the Company underwrites insurance for Hagerty, a portion of which is ceded to Hagerty Re. The amounts attributed to these arrangements are summarized in the following table. Three Months Ended March 31, (dollars in thousands) 2024 2023 Gross written premiums attributable to Hagerty $ 198,282 $ 164,971 Premiums ceded to Hagerty Re $ 152,685 $ 124,628 As of March 31, 2024 and December 31, 2023, reinsurance recoverables on the consolidated balance sheets included $225.3 million and $214.8 million, respectively, due from Hagerty Re.

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Mar. 31, 2024
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders' Equity a) The Company has 50,000,000 shares of no par value common stock authorized. The following table presents a rollforward of changes in common shares issued and outstanding. Three Months Ended March 31, (shares in ones) 2024 2023 Issued and outstanding common shares, beginning of period 13,131,672 13,422,692 Issuance of common shares 1,384 1,817 Repurchase of common shares (109,545) (62,896) Issued and outstanding common shares, end of period 13,023,511 13,361,613 b) The Company also has 10,000,000 shares of no par value preferred stock authorized, of which 600,000 shares were issued and outstanding at March 31, 2024 and December 31, 2023. c) Net income per common share was determined by dividing adjusted net income to common shareholders by the applicable weighted average common shares outstanding. Basic common shares outstanding include restricted stock units that are no longer subject to any contingencies for issuance, but for which corresponding shares have not been issued. Diluted net income per common share is computed by dividing adjusted net income to common shareholders by the weighted average number of common shares and dilutive potential common shares outstanding during the period. The following table presents basic net income per common share and diluted net income per common share. Three Months Ended March 31, (in thousands, except per share amounts) 2024 2023 Net income to common shareholders $ 1,025,184 $ 488,652 Adjustment of redeemable noncontrolling interests (32,602) 13,473 Adjusted net income to common shareholders $ 992,582 $ 502,125 Basic common shares outstanding 13,137 13,450 Dilutive potential common shares from restricted stock units and restricted stock 22 25 Diluted common shares outstanding 13,159 13,475 Basic net income per common share $ 75.56 $ 37.33 Diluted net income per common share $ 75.43 $ 37.26

Contingencies

Contingencies	3 Months Ended
	Mar. 31, 2024
Loss Contingency [Abstract]
Contingencies	Contingencies Contingencies arise in the normal course of the Company's operations and are not expected to have a material impact on the Company's financial condition or results of operations.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net income (loss) to common shareholders	$ 1,025,184	$ 488,652

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024 shares
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	true
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Steven A. Markel [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On February 20, 2024, Steven A. Markel, Chair of the Board and a Director of the Company, adopted a Rule 10b5-1 trading arrangement that is intended to satisfy the affirmative defense of Rule 10b5-1(c) for the sale of up to 3,000 of the Company's common shares until February 14, 2025 (or the date on which all shares have been sold).
Name	Steven A. Markel
Title	Chair of the Board and a Director of the Company
Adoption Date	February 20, 2024
Termination Date	February 14, 2025 (or the date on which all shares have been sold)
Aggregate Available	3,000

Summary Of Significant Accoun_2

Summary Of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation. The consolidated balance sheet as of March 31, 2024 and the related consolidated statements of income and comprehensive income and changes in equity for the three months ended March 31, 2024 and 2023, and the condensed consolidated statements of cash flows for the three months ended March 31, 2024 and 2023 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, 2023 was derived from Markel Group's audited annual consolidated financial statements. The accompanying consolidated financial statements have been prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) and include the accounts of Markel Group and its consolidated subsidiaries, as well as variable interest entities (VIEs) that meet the requirements for consolidation (the Company). All significant intercompany balances and transactions have been eliminated in consolidation. The Company consolidates the results of its Markel Ventures subsidiaries on a one-month lag, with the exception of significant transactions or events that occur during the intervening period. Certain prior period amounts have been reclassified to conform to the current period 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. For a more complete description of the Company's business and accounting policies, readers are urged to review the Company's 2023 Annual Report on Form 10-K.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Standards Not Yet Adopted In November 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . The standard requires public companies to, among other things: (1) disclose, on an annual and interim basis, significant segment expenses that are regularly provided to the chief operating decision maker and included within each reported measure of segment profit or loss; (2) disclose, on an annual and interim basis, an amount for other segment expenses that are not separately disclosed as significant segment expenses and a description of its composition; (3) provide all annual disclosures about a reportable segment's profit or loss and assets currently required by Topic 280 in interim periods; and (4) disclose the title and position of the chief operating decision maker and an explanation of how the chief operating decision maker uses the reported measures of segment profit or loss in assessing segment performance and deciding how to allocate resources. ASU No. 2023-07 becomes effective for the Company in the fourth quarter of 2024 and will be applied using a retrospective approach that requires recasting of all prior periods presented. The standard only impacts required disclosures and will not impact the Company's financial position, results of operations or cash flows. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures . The standard requires public companies, on an annual basis, to provide enhanced rate reconciliation disclosures, including disclosure of specific categories and additional information for reconciling items that meet a quantitative threshold. The standard also requires public companies to, among other things, disaggregate income taxes paid by federal, state and foreign taxes. ASU No. 2023-09 becomes effective for the Company's 2025 Annual Report on Form 10-K. The standard only impacts required disclosures and will not impact the Company's financial position, results of operations or cash flows.

Segment Reporting Disclosures (

Segment Reporting Disclosures (Tables)	3 Months Ended
	Mar. 31, 2024
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Company's Segment Disclosures	The following tables summarize the Company's segment disclosures. Three Months Ended March 31, 2024 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures Other insurance operations Corporate Consolidated Earned premiums $ 1,874,461 $ 253,339 $ — $ — $ (173) $ — $ 2,127,627 Net investment income — — 217,204 1,065 — — 218,269 Net investment gains — — 902,281 — — — 902,281 Products revenues — — — 600,840 — — 600,840 Services and other revenues — — 20,846 538,701 58,091 — 617,638 Total operating revenues 1,874,461 253,339 1,140,331 1,140,606 57,918 — 4,466,655 Losses and loss adjustment expenses: Current accident year (1,201,555) (163,215) — — — — (1,364,770) Prior accident years 97,181 (3,398) — — (16,760) — 77,023 Underwriting, acquisition and insurance expenses: Amortization of policy acquisition costs (373,778) (60,809) — — — — (434,587) Other underwriting expenses (288,999) (13,907) — — (1,259) — (304,165) Products expenses — — — (523,247) — — (523,247) Services and other expenses — — — (513,444) (23,394) — (536,838) Amortization of acquired intangible assets (44,285) (44,285) Operating income $ 107,310 $ 12,010 $ 1,140,331 $ 103,915 $ 16,505 $ (44,285) $ 1,335,786 Interest expense (45,548) Net foreign exchange gains 51,500 Income before income taxes $ 1,341,738 Three Months Ended March 31, 2023 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures Other insurance operations Corporate Consolidated Earned premiums $ 1,710,924 $ 257,234 $ — $ — $ (454) $ — $ 1,967,704 Net investment income — — 158,594 741 — — 159,335 Net investment gains — — 372,563 — — — 372,563 Products revenues — — — 577,926 — — 577,926 Services and other revenues — — (2,380) 526,013 42,228 — 565,861 Total operating revenues 1,710,924 257,234 528,777 1,104,680 41,774 — 3,643,389 Losses and loss adjustment expenses: Current accident year (1,077,546) (166,785) — — — — (1,244,331) Prior accident years 62,628 8,704 — — (15) — 71,317 Underwriting, acquisition and insurance expenses: Amortization of policy acquisition costs (360,354) (61,778) — — — — (422,132) Other underwriting expenses (239,148) (13,141) — — (1,284) — (253,573) Products expenses — — — (515,756) — — (515,756) Services and other expenses — — — (496,746) 16,127 — (480,619) Amortization of acquired intangible assets (44,399) (44,399) Operating income $ 96,504 $ 24,234 $ 528,777 $ 92,178 $ 56,602 $ (44,399) $ 753,896 Interest expense (49,438) Net foreign exchange losses (32,928) Income before income taxes $ 671,530
Reconciliation Of Segment Assets To The Company's Consolidated Balance Sheets	The following table reconciles segment assets to the Company's consolidated balance sheets. (dollars in thousands) March 31, 2024 December 31, 2023 Segment assets: Investing $ 31,699,863 $ 30,542,282 Underwriting 10,317,034 9,897,689 Markel Ventures 5,623,756 5,519,542 Total segment assets 47,640,653 45,959,513 Other insurance operations 9,645,732 9,086,197 Total assets $ 57,286,385 $ 55,045,710

Investments (Tables)

Investments (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Available-For-Sale Investments	The following tables summarize the Company's available-for-sale investments. Commercial and residential mortgage-backed securities include securities issued by U.S. government-sponsored enterprises and U.S. government agencies. The net unrealized holding gains (losses) in the tables below are presented before taxes. March 31, 2024 (dollars in thousands) Amortized Gross Gross Estimated Fixed maturity securities: U.S. Treasury securities $ 4,113,319 $ 12,079 $ (79,408) $ 4,045,990 U.S. government-sponsored enterprises 1,289,119 4,206 (99,430) 1,193,895 Obligations of states, municipalities and political subdivisions 4,041,845 10,059 (205,316) 3,846,588 Foreign governments 1,950,839 4,132 (126,930) 1,828,041 Commercial mortgage-backed securities 2,400,848 4,780 (137,472) 2,268,156 Residential mortgage-backed securities 463,710 155 (22,187) 441,678 Corporate bonds 968,072 5,424 (78,474) 895,022 Total fixed maturity securities 15,227,752 40,835 (749,217) 14,519,370 Short-term investments 2,618,162 597 (1,117) 2,617,642 Investments, available-for-sale $ 17,845,914 $ 41,432 $ (750,334) $ 17,137,012	December 31, 2023 (dollars in thousands) Amortized Gross Gross Estimated Fixed maturity securities: U.S. Treasury securities $ 3,811,293 $ 35,824 $ (62,404) $ 3,784,713 U.S. government-sponsored enterprises 1,225,426 7,292 (89,904) 1,142,814 Obligations of states, municipalities and political subdivisions 4,196,096 14,787 (181,578) 4,029,305 Foreign governments 1,858,845 21,450 (96,874) 1,783,421 Commercial mortgage-backed securities 2,371,406 8,605 (136,353) 2,243,658 Residential mortgage-backed securities 491,949 334 (21,861) 470,422 Corporate bonds 977,271 13,043 (71,915) 918,399 Total fixed maturity securities 14,932,286 101,335 (660,889) 14,372,732 Short-term investments 2,564,620 7,155 (393) 2,571,382 Investments, available-for-sale $ 17,496,906 $ 108,490 $ (661,282) $ 16,944,114
Summary Of Gross Unrealized Investment Losses By Length Of Time That Securities Have Continuously Been In An Unrealized Loss Position	The following tables summarize gross unrealized investment losses on available-for-sale investments by the length of time that securities have continuously been in an unrealized loss position. Unrealized losses on available-for-sale investments are typically the result of declines in the fair value of the investments due to increases in interest rates. March 31, 2024 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Gross Estimated Gross Estimated Gross Fixed maturity securities: U.S. Treasury securities $ 1,553,613 $ (10,383) $ 1,388,322 $ (69,025) $ 2,941,935 $ (79,408) U.S. government-sponsored enterprises 244,720 (3,629) 746,832 (95,801) 991,552 (99,430) Obligations of states, municipalities and political subdivisions 920,869 (8,138) 2,376,770 (197,178) 3,297,639 (205,316) Foreign governments 322,098 (3,059) 1,079,889 (123,871) 1,401,987 (126,930) Commercial mortgage-backed securities 275,805 (4,101) 1,722,270 (133,371) 1,998,075 (137,472) Residential mortgage-backed securities 25,905 (456) 401,845 (21,731) 427,750 (22,187) Corporate bonds 148,340 (2,336) 574,746 (76,138) 723,086 (78,474) Total fixed maturity securities 3,491,350 (32,102) 8,290,674 (717,115) 11,782,024 (749,217) Short-term investments 2,272,608 (1,117) — — 2,272,608 (1,117) Total $ 5,763,958 $ (33,219) $ 8,290,674 $ (717,115) $ 14,054,632 $ (750,334)	December 31, 2023 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Gross Estimated Gross Estimated Gross Fixed maturity securities: U.S. Treasury securities $ 317,027 $ (2,147) $ 1,507,784 $ (60,257) $ 1,824,811 $ (62,404) U.S. government-sponsored enterprises 145,143 (2,134) 723,537 (87,770) 868,680 (89,904) Obligations of states, municipalities and political subdivisions 679,124 (3,881) 2,332,281 (177,697) 3,011,405 (181,578) Foreign governments 49,056 (128) 1,113,616 (96,746) 1,162,672 (96,874) Commercial mortgage-backed securities 169,557 (1,792) 1,790,637 (134,561) 1,960,194 (136,353) Residential mortgage-backed securities 20,420 (80) 431,705 (21,781) 452,125 (21,861) Corporate bonds 34,340 (266) 615,501 (71,649) 649,841 (71,915) Total fixed maturity securities 1,414,667 (10,428) 8,515,061 (650,461) 9,929,728 (660,889) Short-term investments 52,601 (393) — — 52,601 (393) Total $ 1,467,268 $ (10,821) $ 8,515,061 $ (650,461) $ 9,982,329 $ (661,282)
Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturity Securities By Contractual Maturity Date	The amortized cost and estimated fair value of fixed maturity securities at March 31, 2024 are shown below by contractual maturity. (dollars in thousands) Amortized Estimated Due in one year or less $ 1,108,711 $ 1,091,274 Due after one year through five years 5,268,266 5,082,020 Due after five years through ten years 4,482,619 4,278,074 Due after ten years 1,503,598 1,358,168 12,363,194 11,809,536 Commercial mortgage-backed securities 2,400,848 2,268,156 Residential mortgage-backed securities 463,710 441,678 Total fixed maturity securities $ 15,227,752 $ 14,519,370
Components Of Net Investment Income	The following table presents the components of net investment income. Three Months Ended March 31, (dollars in thousands) 2024 2023 Interest: Fixed maturity securities $ 119,476 $ 82,128 Short-term investments 32,184 26,619 Cash and cash equivalents and restricted cash and cash equivalents 39,078 27,601 Dividends on equity securities 32,693 27,482 223,431 163,830 Investment expenses (5,162) (4,495) Net investment income $ 218,269 $ 159,335
Summary Of Net Investment Gains (Losses) And The Change In Net Unrealized Gains On Available-For-Sale Investments	The following table presents the components of net investment gains included in net income and the change in net unrealized losses included in other comprehensive income (loss). Gross realized investment gains and losses on fixed maturity securities, short-term investments and other investments were not material to the consolidated financial statements and are presented on a net basis in the following table. Three Months Ended March 31, (dollars in thousands) 2024 2023 Fixed maturity securities, short-term investments and other investments: Net realized investment losses $ (4,488) $ (3,221) Equity securities: Change in fair value of securities sold during the period 43 5,637 Change in fair value of securities held at the end of the period 906,726 370,147 Total change in fair value 906,769 375,784 Net investment gains $ 902,281 $ 372,563 Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss): Fixed maturity securities $ (148,487) $ 209,179 Short-term investments (7,282) (810) Net increase (decrease) $ (155,769) $ 208,369

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Balances Of Assets Measured At Fair Value On A Recurring Basis	The following tables present the balances of assets measured at fair value on a recurring basis by level within the fair value hierarchy. March 31, 2024 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments: Fixed maturity securities, available-for-sale: U.S. Treasury securities $ — $ 4,045,990 $ — $ 4,045,990 U.S. government-sponsored enterprises — 1,193,895 — 1,193,895 Obligations of states, municipalities and political subdivisions — 3,846,588 — 3,846,588 Foreign governments — 1,828,041 — 1,828,041 Commercial mortgage-backed securities — 2,268,156 — 2,268,156 Residential mortgage-backed securities — 441,678 — 441,678 Corporate bonds — 895,022 — 895,022 Total fixed maturity securities, available-for-sale — 14,519,370 — 14,519,370 Equity securities: Insurance, banks and other financial institutions 4,177,578 — 1,157 4,178,735 Industrial, consumer and all other 6,392,240 — — 6,392,240 Total equity securities 10,569,818 — 1,157 10,570,975 Short-term investments, available-for-sale 2,453,881 163,761 — 2,617,642 Total investments $ 13,023,699 $ 14,683,131 $ 1,157 $ 27,707,987 December 31, 2023 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments: Fixed maturity securities, available-for-sale: U.S. Treasury securities $ — $ 3,784,713 $ — $ 3,784,713 U.S. government-sponsored enterprises — 1,142,814 — 1,142,814 Obligations of states, municipalities and political subdivisions — 4,029,305 — 4,029,305 Foreign governments — 1,783,421 — 1,783,421 Commercial mortgage-backed securities — 2,243,658 — 2,243,658 Residential mortgage-backed securities — 470,422 — 470,422 Corporate bonds — 918,399 — 918,399 Total fixed maturity securities, available-for-sale — 14,372,732 — 14,372,732 Equity securities: Insurance, banks and other financial institutions 3,694,375 — 994 3,695,369 Industrial, consumer and all other 5,882,502 — — 5,882,502 Total equity securities 9,576,877 — 994 9,577,871 Short-term investments, available-for-sale 2,402,099 169,283 — 2,571,382 Total investments $ 11,978,976 $ 14,542,015 $ 994 $ 26,521,985

Products, Services and Other _2

Products, Services and Other Revenues (Tables)	3 Months Ended
	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Schedule Of Revenues From Contracts With Customers By Type	The following tables present revenues from contracts with customers by type, all of which are included in products revenues and services and other revenues, along with a reconciliation to total products revenues and services and other revenues. Three Months Ended March 31, 2024 2023 (dollars in thousands) Markel Ventures Other Total Markel Ventures Other Total Products $ 594,592 $ — $ 594,592 $ 565,895 $ — $ 565,895 Services 498,290 2,133 500,423 486,481 2,854 489,335 Investment management — 19,936 19,936 — 10,459 10,459 Total revenues from contracts with customers 1,092,882 22,069 1,114,951 1,052,376 13,313 1,065,689 Leasing revenues 40,753 — 40,753 41,752 — 41,752 Program services and other fronting fees — 36,030 36,030 — 28,890 28,890 Equity method and other investments income (loss) 5,179 20,846 26,025 1,495 (2,380) (885) Other 727 (8) 719 8,316 25 8,341 Total $ 1,139,541 $ 78,937 $ 1,218,478 $ 1,103,939 $ 39,848 $ 1,143,787

Unpaid Losses And Loss Adjust_2

Unpaid Losses And Loss Adjustment Expenses (Tables)	3 Months Ended
	Mar. 31, 2024
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Reconciliation Of Consolidated Reserves For Losses And Loss Adjustment Expenses	The following table presents a reconciliation of consolidated beginning and ending reserves for losses and loss adjustment expenses. Three Months Ended March 31, (dollars in thousands) 2024 2023 Gross reserves for losses and loss adjustment expenses, beginning of year $ 23,483,321 $ 20,947,898 Reinsurance recoverables on unpaid losses, beginning of year 8,820,567 7,994,884 Net reserves for losses and loss adjustment expenses, beginning of year 14,662,754 12,953,014 Effect of foreign currency rate changes on beginning of year balance (33,620) 36,637 Adjusted net reserves for losses and loss adjustment expenses, beginning of year 14,629,134 12,989,651 Incurred losses and loss adjustment expenses: Current accident year 1,364,770 1,244,331 Prior accident years (77,023) (71,317) Total incurred losses and loss adjustment expenses 1,287,747 1,173,014 Payments: Current accident year 75,509 72,167 Prior accident years 819,185 708,115 Total payments 894,694 780,282 Effect of foreign currency rate changes on current year activity (1,018) (3,649) Change in net reserves for losses and loss adjustment expenses of Markel CATCo Re (see note 10) (16,338) (115,141) Reinsurance recoverable for retroactive reinsurance transaction — (125,067) Net reserves for losses and loss adjustment expenses, end of period 15,004,831 13,138,526 Reinsurance recoverables on unpaid losses 9,140,124 8,168,267 Gross reserves for losses and loss adjustment expenses, end of period $ 24,144,955 $ 21,306,793

Reinsurance (Tables)

Reinsurance (Tables)	3 Months Ended
	Mar. 31, 2024
Reinsurance Disclosures [Abstract]
Effect Of Reinsurance And Retrocessional Reinsurance On Premiums Written And Earned	The following tables summarize the effect of reinsurance and retrocessional reinsurance on premiums written and earned. Three Months Ended March 31, 2024 2023 (dollars in thousands) Direct Assumed Ceded Net Premiums Direct Assumed Ceded Net Premiums Underwriting: Written $ 2,107,467 $ 668,699 $ (543,956) $ 2,232,210 $ 1,969,363 $ 688,895 $ (440,029) $ 2,218,229 Earned $ 2,198,238 $ 392,942 $ (463,380) $ 2,127,800 $ 1,971,876 $ 398,719 $ (402,440) $ 1,968,155 Program services and other fronting: Written 744,958 419,275 (1,164,406) (173) 573,211 204,543 (778,205) (451) Earned 703,682 123,271 (827,126) (173) 641,113 74,717 (716,281) (451) Consolidated: Written $ 2,852,425 $ 1,087,974 $ (1,708,362) $ 2,232,037 $ 2,542,574 $ 893,438 $ (1,218,234) $ 2,217,778 Earned $ 2,901,920 $ 516,213 $ (1,290,506) $ 2,127,627 $ 2,612,989 $ 473,436 $ (1,118,721) $ 1,967,704
Effect Of Reinsurance And Retrocessional Reinsurance On Losses and Loss Adjustment Expenses	The following table summarizes the effect of reinsurance and retrocessional reinsurance on losses and loss adjustment expenses in the Company's underwriting operations. Three Months Ended March 31, (dollars in thousands) 2024 2023 Gross losses and loss adjustment expenses $ 1,693,847 $ 1,392,348 Ceded losses and loss adjustment expenses (406,167) (219,255) Net losses and loss adjustment expenses $ 1,287,680 $ 1,173,093

Life and Annuity Benefits (Tabl

Life and Annuity Benefits (Tables)	3 Months Ended
	Mar. 31, 2024
Liability for Future Policy Benefit, before Reinsurance [Abstract]
Schedule of Future Policyholder Benefits, Life and Annuity [Table Text Block]	The following table presents the components of the Company's liabilities for life and annuity benefits. (dollars in thousands) March 31, 2024 December 31, 2023 Liability for future policyholder benefits $ 528,249 $ 557,763 Deferred profit liability 50,483 52,287 Other 38,534 39,004 Total $ 617,266 $ 649,054
Liability for Future Policy Benefit, Activity [Table Text Block]	The following table presents a rollforward of the present value of the liability for future policyholder benefits. Three Months Ended March 31, (dollars in thousands) 2024 2023 Liability for future policyholder benefits, beginning of year $ 557,763 $ 554,366 Liability for future policyholder benefits at original discount rate, beginning of year 642,877 667,761 Effect of changes in cash flow assumptions — — Effect of actual variances from expected experience — — Adjusted liability for future policyholder benefits, beginning of year 642,877 667,761 Interest accretion 3,605 3,815 Benefit payments (13,290) (13,283) Effect of foreign currency rate changes (11,706) 10,396 Liability for future policyholder benefits at original discount rate, end of period 621,486 668,689 Cumulative effect of changes in discount rate assumptions (93,237) (101,938) Liability for future policyholder benefits, end of period (1) $ 528,249 $ 566,751 (1) The undiscounted liability for future policyholder benefits was $796.8 million and $862.7 million as of March 31, 2024 and 2023, respectively.
Schedule of Additional Details of Liability for Future Policyholder Benefits, Life and Annuity [Table Text Block]	The following table summarizes additional details for the Company's liability for future policyholder benefits. March 31, 2024 December 31, 2023 Weighted-average interest rate: Interest accretion rate 2.3 % 2.3 % Current discount rate 4.1 % 3.8 % Weighted-average liability duration 8.4 years 8.6 years

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Amounts attributable to Markel CATCo Re in Markel's consolidated balance sheet	The Company's consolidated balance sheets include the following amounts attributable to Markel CATCo Re. (dollars in thousands) March 31, 2024 December 31, 2023 Assets Cash and cash equivalents $ 96,252 $ 91,301 Restricted cash and cash equivalents 169,280 173,800 Other assets and receivables due from cedents 18,742 19,292 Total Assets $ 284,274 $ 284,393 Liabilities and Equity Unpaid losses and loss adjustment expenses $ 168,630 $ 184,967 Other liabilities 2,380 1,842 Total Liabilities 171,010 186,809 Shareholders' equity 21,139 21,139 Noncontrolling interests 92,125 76,445 Total Equity 113,264 97,584 Total Liabilities and Equity $ 284,274 $ 284,393

Related Party Disclosures (Tabl

Related Party Disclosures (Tables)	3 Months Ended
	Mar. 31, 2024
Related Party Transactions [Abstract]
Hagarty Related Party	The Company holds a minority ownership interest in Hagerty, which operates primarily as a managing general agent and also includes Hagerty Reinsurance Limited (Hagerty Re), a Bermuda Class 3 reinsurance company. Through the Company's underwriting operations, the Company underwrites insurance for Hagerty, a portion of which is ceded to Hagerty Re. The amounts attributed to these arrangements are summarized in the following table. Three Months Ended March 31, (dollars in thousands) 2024 2023 Gross written premiums attributable to Hagerty $ 198,282 $ 164,971 Premiums ceded to Hagerty Re $ 152,685 $ 124,628

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2024
Stockholders' Equity Note [Abstract]
Schedule of Common Stock Outstanding Roll Forward	The Company has 50,000,000 shares of no par value common stock authorized. The following table presents a rollforward of changes in common shares issued and outstanding. Three Months Ended March 31, (shares in ones) 2024 2023 Issued and outstanding common shares, beginning of period 13,131,672 13,422,692 Issuance of common shares 1,384 1,817 Repurchase of common shares (109,545) (62,896) Issued and outstanding common shares, end of period 13,023,511 13,361,613
Schedule Of Net Income (Loss) Per Common Share	The following table presents basic net income per common share and diluted net income per common share. Three Months Ended March 31, (in thousands, except per share amounts) 2024 2023 Net income to common shareholders $ 1,025,184 $ 488,652 Adjustment of redeemable noncontrolling interests (32,602) 13,473 Adjusted net income to common shareholders $ 992,582 $ 502,125 Basic common shares outstanding 13,137 13,450 Dilutive potential common shares from restricted stock units and restricted stock 22 25 Diluted common shares outstanding 13,159 13,475 Basic net income per common share $ 75.56 $ 37.33 Diluted net income per common share $ 75.43 $ 37.26

Segment Reporting Disclosures_2

Segment Reporting Disclosures (Company's Segment Disclosures) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Earned premiums	$ 2,127,627	$ 1,967,704
Net investment income	218,269	159,335
Net investment gains	902,281	372,563
Products revenues	600,840	577,926
Services and other revenues	617,638	565,861
Operating revenues	4,466,655	3,643,389
Losses and loss adjustment expenses, current accident year	(1,364,770)	(1,244,331)
Losses and loss adjustment expenses, prior accident year	77,023	71,317
Amortization of policy acquisition costs	(434,587)	(422,132)
Other underwriting expenses	(304,165)	(253,573)
Products expenses	(523,247)	(515,756)
Services and other expenses	(536,838)	(480,619)
Amortization of acquired intangible assets	(44,285)	(44,399)
Operating Income	1,335,786	753,896
Interest expense	(45,548)	(49,438)
Net foreign exchange gains (losses)	51,500	(32,928)
Income (Loss) before income taxes	1,341,738	671,530
Insurance [Member]
Segment Reporting Information [Line Items]
Earned premiums	1,874,461	1,710,924
Net investment income	0	0
Net investment gains	0	0
Products revenues	0	0
Services and other revenues	0	0
Operating revenues	1,874,461	1,710,924
Losses and loss adjustment expenses, current accident year	(1,201,555)	(1,077,546)
Losses and loss adjustment expenses, prior accident year	97,181	62,628
Amortization of policy acquisition costs	(373,778)	(360,354)
Other underwriting expenses	(288,999)	(239,148)
Products expenses	0	0
Services and other expenses	0	0
Operating Income	107,310	96,504
Reinsurance [Member]
Segment Reporting Information [Line Items]
Earned premiums	253,339	257,234
Net investment income	0	0
Net investment gains	0	0
Products revenues	0	0
Services and other revenues	0	0
Operating revenues	253,339	257,234
Losses and loss adjustment expenses, current accident year	(163,215)	(166,785)
Losses and loss adjustment expenses, prior accident year	(3,398)	8,704
Amortization of policy acquisition costs	(60,809)	(61,778)
Other underwriting expenses	(13,907)	(13,141)
Products expenses	0	0
Services and other expenses	0	0
Operating Income	12,010	24,234
Investing [Member]
Segment Reporting Information [Line Items]
Earned premiums	0	0
Net investment income	217,204	158,594
Net investment gains	902,281	372,563
Products revenues	0	0
Services and other revenues	20,846	(2,380)
Operating revenues	1,140,331	528,777
Losses and loss adjustment expenses, current accident year	0	0
Losses and loss adjustment expenses, prior accident year	0	0
Amortization of policy acquisition costs	0	0
Other underwriting expenses	0	0
Products expenses	0	0
Services and other expenses	0	0
Operating Income	1,140,331	528,777
Markel Ventures [Member]
Segment Reporting Information [Line Items]
Earned premiums	0	0
Net investment income	1,065	741
Net investment gains	0	0
Products revenues	600,840	577,926
Services and other revenues	538,701	526,013
Operating revenues	1,140,606	1,104,680
Losses and loss adjustment expenses, current accident year	0	0
Losses and loss adjustment expenses, prior accident year	0	0
Amortization of policy acquisition costs	0	0
Other underwriting expenses	0	0
Products expenses	(523,247)	(515,756)
Services and other expenses	(513,444)	(496,746)
Operating Income	103,915	92,178
Other Insurance Operations [Member]
Segment Reporting Information [Line Items]
Earned premiums	(173)	(454)
Net investment income	0	0
Net investment gains	0	0
Products revenues	0	0
Services and other revenues	58,091	42,228
Operating revenues	57,918	41,774
Losses and loss adjustment expenses, current accident year	0	0
Losses and loss adjustment expenses, prior accident year	(16,760)	(15)
Amortization of policy acquisition costs	0	0
Other underwriting expenses	(1,259)	(1,284)
Products expenses	0	0
Services and other expenses	(23,394)	16,127
Operating Income	16,505	56,602
Corporate [Member]
Segment Reporting Information [Line Items]
Earned premiums	0	0
Net investment income	0	0
Net investment gains	0	0
Products revenues	0	0
Services and other revenues	0	0
Operating revenues	0	0
Losses and loss adjustment expenses, current accident year	0	0
Losses and loss adjustment expenses, prior accident year	0	0
Amortization of policy acquisition costs	0	0
Other underwriting expenses	0	0
Products expenses	0	0
Services and other expenses	0	0
Amortization of acquired intangible assets	(44,285)	(44,399)
Operating Income	$ (44,285)	$ (44,399)

Segment Reporting Disclosures_3

Segment Reporting Disclosures (Reconciliation Of Segment Assets To The Company's Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Assets	$ 57,286,385	$ 55,045,710
Other Insurance Operations [Member]
Segment Reporting Information [Line Items]
Assets	9,645,732	9,086,197
Segment assets [Member]
Segment Reporting Information [Line Items]
Assets	47,640,653	45,959,513
Segment assets [Member] | Investing [Member]
Segment Reporting Information [Line Items]
Assets	31,699,863	30,542,282
Segment assets [Member] | Underwriting Segments [Member]
Segment Reporting Information [Line Items]
Assets	10,317,034	9,897,689
Segment assets [Member] | Markel Ventures [Member]
Segment Reporting Information [Line Items]
Assets	$ 5,623,756	$ 5,519,542

Investments (Narrative) (Detail

Investments (Narrative) (Details) $ in Thousands	Mar. 31, 2024 USD ($) securities	Dec. 31, 2023 USD ($) securities
Schedule of Investments [Line Items]
Available-for-sale fixed maturity securities in unrealized loss position, number of positions | securities	1,578	1,386
Available-for-sale securities, estimated fair value	$ 14,054,632	$ 9,982,329
Available-for-sale securities, gross unrealized holding losses	$ (750,334)	$ (661,282)
Number of available-for-sale fixed maturity securities positions in a continuous unrealized loss position for one year or longer at period end | securities	1,126	1,131
Available-for-sale securities, estimated fair value, 12 months or longer	$ 8,290,674	$ 8,515,061
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(717,115)	(650,461)
Investments, available-for-sale, allowance for credit losses	$ 0	$ 0

Investments (Available-For-Sale

Investments (Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, amortized cost	$ 15,227,752	$ 14,932,286
Available-for-sale fixed maturity investments, gross unrealized holding gains	40,835	101,335
Available-for-sale fixed maturity investments, gross unrealized holding losses	(749,217)	(660,889)
Available-for-sale fixed maturity investments, estimated fair value	14,519,370	14,372,732
Short-term investments, available-for-sale, amortized cost	2,618,162	2,564,620
Short-term investments, available-for-sale, gross unrealized holding gains	597	7,155
Short-term investments, available-for-sale, gross unrealized holding losses	(1,117)	(393)
Short-term investments, available-for-sale, estimated fair value	2,617,642	2,571,382
Investments, available-for-sale, amortized cost	17,845,914	17,496,906
Investments, available-for-sale, gross unrealized holding gains	41,432	108,490
Investments, available-for-sale, gross unrealized holding losses	(750,334)	(661,282)
Investments, available-for-sale, estimated fair value	17,137,012	16,944,114
U.S. Treasury securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, amortized cost	4,113,319	3,811,293
Available-for-sale fixed maturity investments, gross unrealized holding gains	12,079	35,824
Available-for-sale fixed maturity investments, gross unrealized holding losses	(79,408)	(62,404)
Available-for-sale fixed maturity investments, estimated fair value	4,045,990	3,784,713
U.S. government-sponsored enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, amortized cost	1,289,119	1,225,426
Available-for-sale fixed maturity investments, gross unrealized holding gains	4,206	7,292
Available-for-sale fixed maturity investments, gross unrealized holding losses	(99,430)	(89,904)
Available-for-sale fixed maturity investments, estimated fair value	1,193,895	1,142,814
Obligations of states, municipalities and political subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, amortized cost	4,041,845	4,196,096
Available-for-sale fixed maturity investments, gross unrealized holding gains	10,059	14,787
Available-for-sale fixed maturity investments, gross unrealized holding losses	(205,316)	(181,578)
Available-for-sale fixed maturity investments, estimated fair value	3,846,588	4,029,305
Foreign governments [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, amortized cost	1,950,839	1,858,845
Available-for-sale fixed maturity investments, gross unrealized holding gains	4,132	21,450
Available-for-sale fixed maturity investments, gross unrealized holding losses	(126,930)	(96,874)
Available-for-sale fixed maturity investments, estimated fair value	1,828,041	1,783,421
Commercial mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, amortized cost	2,400,848	2,371,406
Available-for-sale fixed maturity investments, gross unrealized holding gains	4,780	8,605
Available-for-sale fixed maturity investments, gross unrealized holding losses	(137,472)	(136,353)
Available-for-sale fixed maturity investments, estimated fair value	2,268,156	2,243,658
Residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, amortized cost	463,710	491,949
Available-for-sale fixed maturity investments, gross unrealized holding gains	155	334
Available-for-sale fixed maturity investments, gross unrealized holding losses	(22,187)	(21,861)
Available-for-sale fixed maturity investments, estimated fair value	441,678	470,422
Corporate bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, amortized cost	968,072	977,271
Available-for-sale fixed maturity investments, gross unrealized holding gains	5,424	13,043
Available-for-sale fixed maturity investments, gross unrealized holding losses	(78,474)	(71,915)
Available-for-sale fixed maturity investments, estimated fair value	$ 895,022	$ 918,399

Investments (Summary Of Gross U

Investments (Summary Of Gross Unrealized Investment Losses By Length Of Time That Securities Have Continuously Been In An Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	$ 5,763,958	$ 1,467,268
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(33,219)	(10,821)
Available-for-sale securities, estimated fair value, 12 months or longer	8,290,674	8,515,061
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(717,115)	(650,461)
Available-for-sale securities, estimated fair value	14,054,632	9,982,329
Available-for-sale securities, gross unrealized holding losses	(750,334)	(661,282)
Short-term investments, estimated fair value, less than 12 months	2,272,608	52,601
Short-term investments, gross unrealized holding losses, less than 12 months	(1,117)	(393)
Short-term investments, estimated fair value, 12 months or longer	0	0
Short-term investments, gross unrealized holding losses, 12 months or longer	0	0
Short-term investments, estimated fair value	2,272,608	52,601
Short-term investments, gross unrealized holding losses	(1,117)	(393)
Fixed maturities, available-for-sale, amortized cost	15,227,752	14,932,286
Available-for-sale fixed maturity investments, gross unrealized holding gains	40,835	101,335
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(749,217)	(660,889)
Available-for-sale fixed maturity investments, estimated fair value	14,519,370	14,372,732
U.S. Treasury securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	1,553,613	317,027
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(10,383)	(2,147)
Available-for-sale securities, estimated fair value, 12 months or longer	1,388,322	1,507,784
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(69,025)	(60,257)
Available-for-sale securities, estimated fair value	2,941,935	1,824,811
Available-for-sale securities, gross unrealized holding losses	(79,408)	(62,404)
Fixed maturities, available-for-sale, amortized cost	4,113,319	3,811,293
Available-for-sale fixed maturity investments, gross unrealized holding gains	12,079	35,824
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(79,408)	(62,404)
Available-for-sale fixed maturity investments, estimated fair value	4,045,990	3,784,713
U.S. government-sponsored enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	244,720	145,143
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(3,629)	(2,134)
Available-for-sale securities, estimated fair value, 12 months or longer	746,832	723,537
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(95,801)	(87,770)
Available-for-sale securities, estimated fair value	991,552	868,680
Available-for-sale securities, gross unrealized holding losses	(99,430)	(89,904)
Fixed maturities, available-for-sale, amortized cost	1,289,119	1,225,426
Available-for-sale fixed maturity investments, gross unrealized holding gains	4,206	7,292
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(99,430)	(89,904)
Available-for-sale fixed maturity investments, estimated fair value	1,193,895	1,142,814
Obligations of states, municipalities and political subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	920,869	679,124
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(8,138)	(3,881)
Available-for-sale securities, estimated fair value, 12 months or longer	2,376,770	2,332,281
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(197,178)	(177,697)
Available-for-sale securities, estimated fair value	3,297,639	3,011,405
Available-for-sale securities, gross unrealized holding losses	(205,316)	(181,578)
Fixed maturities, available-for-sale, amortized cost	4,041,845	4,196,096
Available-for-sale fixed maturity investments, gross unrealized holding gains	10,059	14,787
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(205,316)	(181,578)
Available-for-sale fixed maturity investments, estimated fair value	3,846,588	4,029,305
Foreign governments [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	322,098	49,056
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(3,059)	(128)
Available-for-sale securities, estimated fair value, 12 months or longer	1,079,889	1,113,616
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(123,871)	(96,746)
Available-for-sale securities, estimated fair value	1,401,987	1,162,672
Available-for-sale securities, gross unrealized holding losses	(126,930)	(96,874)
Fixed maturities, available-for-sale, amortized cost	1,950,839	1,858,845
Available-for-sale fixed maturity investments, gross unrealized holding gains	4,132	21,450
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(126,930)	(96,874)
Available-for-sale fixed maturity investments, estimated fair value	1,828,041	1,783,421
Commercial mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	275,805	169,557
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(4,101)	(1,792)
Available-for-sale securities, estimated fair value, 12 months or longer	1,722,270	1,790,637
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(133,371)	(134,561)
Available-for-sale securities, estimated fair value	1,998,075	1,960,194
Available-for-sale securities, gross unrealized holding losses	(137,472)	(136,353)
Fixed maturities, available-for-sale, amortized cost	2,400,848	2,371,406
Available-for-sale fixed maturity investments, gross unrealized holding gains	4,780	8,605
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(137,472)	(136,353)
Available-for-sale fixed maturity investments, estimated fair value	2,268,156	2,243,658
Residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	25,905	20,420
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(456)	(80)
Available-for-sale securities, estimated fair value, 12 months or longer	401,845	431,705
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(21,731)	(21,781)
Available-for-sale securities, estimated fair value	427,750	452,125
Available-for-sale securities, gross unrealized holding losses	(22,187)	(21,861)
Fixed maturities, available-for-sale, amortized cost	463,710	491,949
Available-for-sale fixed maturity investments, gross unrealized holding gains	155	334
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(22,187)	(21,861)
Available-for-sale fixed maturity investments, estimated fair value	441,678	470,422
Corporate bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	148,340	34,340
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(2,336)	(266)
Available-for-sale securities, estimated fair value, 12 months or longer	574,746	615,501
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(76,138)	(71,649)
Available-for-sale securities, estimated fair value	723,086	649,841
Available-for-sale securities, gross unrealized holding losses	(78,474)	(71,915)
Fixed maturities, available-for-sale, amortized cost	968,072	977,271
Available-for-sale fixed maturity investments, gross unrealized holding gains	5,424	13,043
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(78,474)	(71,915)
Available-for-sale fixed maturity investments, estimated fair value	895,022	918,399
Total fixed maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	3,491,350	1,414,667
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(32,102)	(10,428)
Available-for-sale securities, estimated fair value, 12 months or longer	8,290,674	8,515,061
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(717,115)	(650,461)
Available-for-sale securities, estimated fair value	11,782,024	9,929,728
Available-for-sale securities, gross unrealized holding losses	$ (749,217)	$ (660,889)

Investments (Schedule Of Amorti

Investments (Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturity Securities By Contractual Maturity Date) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Due in one year or less, amortized cost	$ 1,108,711
Due after one year through five years, amortized cost	5,268,266
Due after five years through ten years, amortized cost	4,482,619
Due after ten years, amortized cost	1,503,598
Amortized cost, sub-total	12,363,194
Total fixed maturities, amortized cost	15,227,752	$ 14,932,286
Due in one year or less, estimated fair value	1,091,274
Due after one year through five years, estimated fair value	5,082,020
Due after five years through ten years, estimated fair value	4,278,074
Due after ten years, estimated fair value	1,358,168
Estimated fair value, sub-total	11,809,536
Total fixed maturities, estimated fair value	14,519,370	14,372,732
Commercial mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	2,400,848
Total fixed maturities, amortized cost	2,400,848	2,371,406
Fixed maturities, estimated fair value	2,268,156
Total fixed maturities, estimated fair value	2,268,156	2,243,658
Residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	463,710
Total fixed maturities, amortized cost	463,710	491,949
Fixed maturities, estimated fair value	441,678
Total fixed maturities, estimated fair value	$ 441,678	$ 470,422

Investments (Components Of Net

Investments (Components Of Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Dividends on equity securities	$ 32,693	$ 27,482
Total investment income	223,431	163,830
Investment expenses	(5,162)	(4,495)
Net investment income	218,269	159,335
Fixed Maturities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Interest income	119,476	82,128
Short-term investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Interest income	32,184	26,619
Cash and Cash Equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Interest income	$ 39,078	$ 27,601

Investments (Summary Of Net Inv

Investments (Summary Of Net Investment Gains (Losses) And The Change In Net Unrealized Gains On Investments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Gain (Loss) on Securities [Line Items]
Debt Securities, Available-for-Sale, Realized Gain (Loss)	$ (4,488)	$ (3,221)
Equity securities, Change in fair value of securities sold during the period	43	5,637
Equity securities, Change in fair value of securities held at the end of the period	906,726	370,147
Total change in fair value of equity securities	906,769	375,784
Net investment gains (losses)	902,281	372,563
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss):	(155,769)	208,369
Fixed Maturities [Member]
Gain (Loss) on Securities [Line Items]
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss):	(148,487)	209,179
Short-term investments [Member]
Gain (Loss) on Securities [Line Items]
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss):	$ (7,282)	$ (810)

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - Fair value, nonrecurring [Member] - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on a nonrecurring basis	$ 0	$ 0
Liabilities measured at fair value on a nonrecurring basis	$ 0	$ 0

Fair Value Measurements (Balanc

Fair Value Measurements (Balances Of Assets Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	$ 14,519,370	$ 14,372,732
Equity securities	10,570,975	9,577,871
Short-term investments, available-for-sale	2,617,642	2,571,382
Total Investments	27,707,987	26,521,985
U.S. Treasury securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	4,045,990	3,784,713
U.S. government-sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,193,895	1,142,814
Obligations of states, municipalities and political subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	3,846,588	4,029,305
Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,828,041	1,783,421
Commercial mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	2,268,156	2,243,658
Residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	441,678	470,422
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	895,022	918,399
Fair value, recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	14,519,370	14,372,732
Equity securities	10,570,975	9,577,871
Short-term investments, available-for-sale	2,617,642	2,571,382
Total Investments	27,707,987	26,521,985
Fair value, recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Equity securities	10,569,818	9,576,877
Short-term investments, available-for-sale	2,453,881	2,402,099
Total Investments	13,023,699	11,978,976
Fair value, recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	14,519,370	14,372,732
Equity securities	0	0
Short-term investments, available-for-sale	163,761	169,283
Total Investments	14,683,131	14,542,015
Fair value, recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Equity securities	1,157	994
Short-term investments, available-for-sale	0	0
Total Investments	1,157	994
Fair value, recurring [Member] | U.S. Treasury securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	4,045,990	3,784,713
Fair value, recurring [Member] | U.S. Treasury securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | U.S. Treasury securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	4,045,990	3,784,713
Fair value, recurring [Member] | U.S. Treasury securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | U.S. government-sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,193,895	1,142,814
Fair value, recurring [Member] | U.S. government-sponsored enterprises [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | U.S. government-sponsored enterprises [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,193,895	1,142,814
Fair value, recurring [Member] | U.S. government-sponsored enterprises [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Obligations of states, municipalities and political subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	3,846,588	4,029,305
Fair value, recurring [Member] | Obligations of states, municipalities and political subdivisions [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Obligations of states, municipalities and political subdivisions [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	3,846,588	4,029,305
Fair value, recurring [Member] | Obligations of states, municipalities and political subdivisions [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,828,041	1,783,421
Fair value, recurring [Member] | Foreign governments [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Foreign governments [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,828,041	1,783,421
Fair value, recurring [Member] | Foreign governments [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Commercial mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	2,268,156	2,243,658
Fair value, recurring [Member] | Commercial mortgage-backed securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Commercial mortgage-backed securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	2,268,156	2,243,658
Fair value, recurring [Member] | Commercial mortgage-backed securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	441,678	470,422
Fair value, recurring [Member] | Residential mortgage-backed securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Residential mortgage-backed securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	441,678	470,422
Fair value, recurring [Member] | Residential mortgage-backed securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	895,022	918,399
Fair value, recurring [Member] | Corporate bonds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Corporate bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	895,022	918,399
Fair value, recurring [Member] | Corporate bonds [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Insurance, banks and other financial institutions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	4,178,735	3,695,369
Fair value, recurring [Member] | Insurance, banks and other financial institutions [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	4,177,578	3,694,375
Fair value, recurring [Member] | Insurance, banks and other financial institutions [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0	0
Fair value, recurring [Member] | Insurance, banks and other financial institutions [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	1,157	994
Fair value, recurring [Member] | Industrial, consumer and all other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	6,392,240	5,882,502
Fair value, recurring [Member] | Industrial, consumer and all other [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	6,392,240	5,882,502
Fair value, recurring [Member] | Industrial, consumer and all other [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0	0
Fair value, recurring [Member] | Industrial, consumer and all other [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	$ 0	$ 0

Equity Method Investments (Deta

Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 633.6		$ 605.9
Income (loss) from equity method investments	25.9	$ (1.5)
Hagerty, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 238.4		$ 237.4
Equity method investment, ownership percentage	23%		23%
Equity method investment, quoted market value	$ 713.7		$ 608.4

Products, Services and Other _3

Products, Services and Other Revenues (Schedule Of Revenues From Contracts With Customers By Type) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Leasing revenues	$ 40,753	$ 41,752
Program services and other fronting fees	36,030	28,890
Equity method and other investments income (loss)	26,025	(885)
Other revenues (losses)	719	8,341
Products Revenues and Services and Other Revenues	1,218,478	1,143,787
Markel Ventures [Member]
Disaggregation of Revenue [Line Items]
Leasing revenues	40,753	41,752
Program services and other fronting fees	0	0
Equity method and other investments income (loss)	5,179	1,495
Other revenues (losses)	727	8,316
Products Revenues and Services and Other Revenues	1,139,541	1,103,939
Other Insurance Operations [Member]
Disaggregation of Revenue [Line Items]
Leasing revenues	0	0
Program services and other fronting fees	36,030	28,890
Equity method and other investments income (loss)	20,846	(2,380)
Other revenues (losses)	(8)	25
Products Revenues and Services and Other Revenues	78,937	39,848
Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	1,114,951	1,065,689
Revenue from contracts with customers [Member] | Products [Member]
Disaggregation of Revenue [Line Items]
Other revenues	594,592	565,895
Revenue from contracts with customers [Member] | Services [Member]
Disaggregation of Revenue [Line Items]
Other revenues	500,423	489,335
Revenue from contracts with customers [Member] | Investment management [Member]
Disaggregation of Revenue [Line Items]
Other revenues	19,936	10,459
Revenue from contracts with customers [Member] | Markel Ventures [Member]
Disaggregation of Revenue [Line Items]
Other revenues	1,092,882	1,052,376
Revenue from contracts with customers [Member] | Markel Ventures [Member] | Products [Member]
Disaggregation of Revenue [Line Items]
Other revenues	594,592	565,895
Revenue from contracts with customers [Member] | Markel Ventures [Member] | Services [Member]
Disaggregation of Revenue [Line Items]
Other revenues	498,290	486,481
Revenue from contracts with customers [Member] | Markel Ventures [Member] | Investment management [Member]
Disaggregation of Revenue [Line Items]
Other revenues	0	0
Revenue from contracts with customers [Member] | Other Insurance Operations [Member]
Disaggregation of Revenue [Line Items]
Other revenues	22,069	13,313
Revenue from contracts with customers [Member] | Other Insurance Operations [Member] | Products [Member]
Disaggregation of Revenue [Line Items]
Other revenues	0	0
Revenue from contracts with customers [Member] | Other Insurance Operations [Member] | Services [Member]
Disaggregation of Revenue [Line Items]
Other revenues	2,133	2,854
Revenue from contracts with customers [Member] | Other Insurance Operations [Member] | Investment management [Member]
Disaggregation of Revenue [Line Items]
Other revenues	$ 19,936	$ 10,459

Products, Services and Other _4

Products, Services and Other Revenues (Schedule Of Receivables And Customer Deposits Related To Contracts With Customers) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Contracts with customers [Member]
Receivables [Line Items]
Accounts Receivable, before Allowance for Credit Loss	$ 537.6	$ 616.4

Unpaid Losses And Loss Adjust_3

Unpaid Losses And Loss Adjustment Expenses (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable (adverse) development on prior years' loss reserves	$ 77,023	$ 71,317
Reinsurance recoverable for retroactive reinsurance transaction	0	(125,067)
Insurance [Member] | International professional liability and marine and energy product lines [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable (adverse) development on prior years' loss reserves	$ 64,800
Insurance [Member] | Marine and energy, property, workers' compensation and programs product lines [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable (adverse) development on prior years' loss reserves		63,800
Reinsurance [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Reinsurance recoverable for retroactive reinsurance transaction		$ (125,100)

Unpaid Losses And Loss Adjust_4

Unpaid Losses And Loss Adjustment Expenses (Reconciliation Of Consolidated Reserves For Losses And Loss Adjustment Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Gross reserves for losses and loss adjustment expenses, beginning of year	$ 23,483,321	$ 20,947,898
Reinsurance recoverable on unpaid losses, beginning of year	8,820,567	7,994,884
Net reserves for losses and loss adjustment expenses, beginning of year	14,662,754	12,953,014
Effect of foreign currency rate changes on beginning of year balance	(33,620)	36,637
Adjusted net reserves for losses and loss adjustment expenses, beginning of year	14,629,134	12,989,651
Incurred losses and loss adjustment expenses, current accident years	1,364,770	1,244,331
Incurred losses and loss adjustment expenses, prior accident years	(77,023)	(71,317)
Total incurred losses and loss adjustment expenses	1,287,747	1,173,014
Payments, current accident year	75,509	72,167
Payments, prior accident years	819,185	708,115
Total payments	894,694	780,282
Effect of foreign currency rate changes on current year activity	(1,018)	(3,649)
Net reserves for losses and loss adjustment expenses of Markel CATCo Re	(16,338)	(115,141)
Reinsurance recoverable for retroactive reinsurance transaction	0	(125,067)
Net reserves for losses and loss adjustment expenses, end of period	15,004,831	13,138,526
Reinsurance recoverable on unpaid losses	9,140,124	8,168,267
Gross reserves for losses and loss adjustment expenses, end of period	$ 24,144,955	$ 21,306,793

Reinsurance (Narrative) (Detail

Reinsurance (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Percentage of ceded earned premiums to gross earned premiums	38%	36%
Percentage of assumed earned premiums to net earned premiums	24%	24%
Program services and other fronting [Member]
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross losses and loss adjustment expenses	$ 603.7	$ 496.6

Reinsurance (Effect Of Reinsura

Reinsurance (Effect Of Reinsurance And Retrocessional Reinsurance On Premiums Written And Earned) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Effects of Reinsurance [Line Items]
Direct premiums written	$ 2,852,425	$ 2,542,574
Direct premiums earned	2,901,920	2,612,989
Assumed premiums written	1,087,974	893,438
Assumed premiums earned	516,213	473,436
Ceded premiums written	(1,708,362)	(1,218,234)
Ceded premiums earned	(1,290,506)	(1,118,721)
Net premiums written	2,232,037	2,217,778
Net premiums earned	2,127,627	1,967,704
Underwriting [Member]
Effects of Reinsurance [Line Items]
Direct premiums written	2,107,467	1,969,363
Direct premiums earned	2,198,238	1,971,876
Assumed premiums written	668,699	688,895
Assumed premiums earned	392,942	398,719
Ceded premiums written	(543,956)	(440,029)
Ceded premiums earned	(463,380)	(402,440)
Net premiums written	2,232,210	2,218,229
Net premiums earned	2,127,800	1,968,155
Program services and other fronting [Member]
Effects of Reinsurance [Line Items]
Direct premiums written	744,958	573,211
Direct premiums earned	703,682	641,113
Assumed premiums written	419,275	204,543
Assumed premiums earned	123,271	74,717
Ceded premiums written	(1,164,406)	(778,205)
Ceded premiums earned	(827,126)	(716,281)
Net premiums written	(173)	(451)
Net premiums earned	$ (173)	$ (451)

Reinsurance Reinsurance (Effect

Reinsurance Reinsurance (Effect Of Reinsurance And Retrocessional Reinsurance On Losses) (Details) - Underwriting [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Effects of Reinsurance [Line Items]
Gross losses and loss adjustment expenses	$ 1,693,847	$ 1,392,348
Ceded losses and loss adjustment expenses	(406,167)	(219,255)
Net losses and loss adjustment expenses	$ 1,287,680	$ 1,173,093

Life and Annuity Benefits (Sche

Life and Annuity Benefits (Schedule of Future Policyholder Benefits) (Details) - USD ($) $ in Thousands	Mar. 31, 2024		Dec. 31, 2023	Mar. 31, 2023	[1]	Dec. 31, 2022
Liability for Future Policy Benefit, before Reinsurance [Abstract]
Liability for future policyholder benefits	$ 528,249	[1]	$ 557,763	$ 566,751		$ 554,366
Deferred profit liability	50,483		52,287
Other	38,534		39,004
Total	$ 617,266		$ 649,054
[1]The undiscounted liability for future policyholder benefits was $796.8 million and $862.7 million as of March 31, 2024 and 2023, respectively.

Life and Annuity Benefits (Liab

Life and Annuity Benefits (Liability for Future Policy Benefit, Activity) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefits Activity [Abstract]
Liability for future policyholder benefits, beginning of year		$ 557,763	$ 554,366
Liability for future policyholder benefits at original discount rate, beginning of year		642,877	667,761
Effect of changes in cash flow assumptions				$ 0	$ 0
Effect of actual variances from expected experience				0	$ 0
Adjusted liability for future policyholder benefits, beginning of year		642,877	667,761
Interest accretion		3,605	3,815
Benefit payments		(13,290)	(13,283)
Effect of foreign currency changes		(11,706)	10,396
Liability for future policy holder benefits t original discount rate, end of period		621,486	668,689
Cumulative effect of changes in discount rate assumptions		(93,237)	(101,938)
Liability for future policyholder benefits, beginning of year, ending of period	[1]	528,249	$ 566,751
Undiscounted liability for future policyholder benefits		$ 796,800		$ 862,700
[1]The undiscounted liability for future policyholder benefits was $796.8 million and $862.7 million as of March 31, 2024 and 2023, respectively.

Life and Annuity Benefits (Sc_2

Life and Annuity Benefits (Schedule of Additional Details of Liability for Future Policyholder Benefits) (Details)	Mar. 31, 2024 Rate	Dec. 31, 2023 Rate
Schedule of Additional Details of Liability for Future Policyholder Benefits, Life and Annuity Benefits [Abstract]
Interest accretion rate	2.30%	2.30%
Current discount rate	4.10%	3.80%
Weighted-average liability duration	8 years 4 months 24 days	8 years 7 months 6 days

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Jun. 30, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Mar. 31, 2022
Variable Interest Entity [Line Items]
Cash funding used to purchase Markel CATCo Funds' interests in Markel CATCo Re					$ 45,100
Returned capital from Markel CATCo Re	$ 24,900
Investment in Markel CATCo Re		$ 20,100		$ 20,100
Percentage of Markel CATCo Re net equity held by the Company		18%		23%
Tail risk cover in Markel CATCo transaction		$ 95,000
Favorable development on prior years' loss reserves		77,023	$ 71,317
Redemption of Markel CATCo Re noncontrolling interests		0	(88,997)
Noncontrolling Interests [Member]
Variable Interest Entity [Line Items]
Redemption of Markel CATCo Re noncontrolling interests			(62,646)
Markel CATCo Re
Variable Interest Entity [Line Items]
Favorable development on prior years' loss reserves		$ (15,700)	$ (44,800)

Variable Interest Entities (Mar

Variable Interest Entities (Markel CATCo Re Balance Sheet) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 3,627,142	$ 3,747,060
Restricted cash and cash equivalents	649,598	584,974
Total Assets	57,286,385	55,045,710
Unpaid losses and loss adjustment expenses	24,144,955	23,483,321	$ 21,306,793	$ 20,947,898
Other liabilities	3,959,161	3,927,498
Total Liabilities	40,968,869	39,519,817
Shareholders' equity	15,729,719	14,983,928
Noncontrolling interests	87,804	72,280
Total Equity	15,817,523	15,056,208
Total Liabilities and Equity	57,286,385	55,045,710
Markel CATCo Re
Variable Interest Entity [Line Items]
Cash and cash equivalents	96,252	91,301
Restricted cash and cash equivalents	169,280	173,800
Other assets and receivables due from cedents	18,742	19,292
Total Assets	284,274	284,393
Unpaid losses and loss adjustment expenses	168,630	184,967
Other liabilities	2,380	1,842
Total Liabilities	171,010	186,809
Shareholders' equity	21,139	21,139
Noncontrolling interests	92,125	76,445
Total Equity	113,264	97,584
Total Liabilities and Equity	$ 284,274	$ 284,393

Related Party Transactions (Nar

Related Party Transactions (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Related Party Transaction [Line Items]
Services and other revenues	$ 617,638	$ 565,861
Reinsurance recoverables	9,575,066		$ 9,235,501
Premiums ceded	1,708,362	1,218,234
Nephila Reinsurers [Member]
Related Party Transaction [Line Items]
Reinsurance recoverables	785,900		794,300
Hagerty, Inc. [Member]
Related Party Transaction [Line Items]
Reinsurance recoverables	225,300		$ 214,800
Gross premium volume	198,282	164,971
Premiums ceded	152,685	124,628
Insurance-linked Securities Operations [Member] | Unconsolidated entities managed by Nephila [Member]
Related Party Transaction [Line Items]
Services and other revenues	19,200	9,800
Program services and other fronting [Member] | Nephila Reinsurers [Member]
Related Party Transaction [Line Items]
Gross premium volume	353,100	236,900
Premiums ceded	$ 353,100	$ 236,900

Related Party Disclosures (Haga

Related Party Disclosures (Hagarty) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Related Party Transaction [Line Items]
Premiums ceded	$ 1,708,362	$ 1,218,234
Hagerty, Inc. [Member]
Related Party Transaction [Line Items]
Gross premium volume	198,282	164,971
Premiums ceded	$ 152,685	$ 124,628

Shareholders' Equity (Narrative

Shareholders' Equity (Narrative) (Details) - $ / shares	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Earnings Per Share [Line Items]
Common stock, shares authorized	50,000,000
Common stock, no par value	$ 0
Preferred stock, shares authorized	10,000,000
Preferred stock, no par value	$ 0
Common Stock [Member]
Earnings Per Share [Line Items]
Shares, outstanding	13,023,511	13,131,672	13,361,613	13,422,692
Series A preferred stock [Member]
Earnings Per Share [Line Items]
Preferred stock, shares issued	600,000	600,000
Preferred stock, shares outstanding	600,000	600,000

Shareholders' Equity (Schedule

Shareholders' Equity (Schedule of Common Stock Outstanding Roll Forward) (Details) - Common Stock [Member] - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Class of Stock [Line Items]
Shares, Issued, Beginning Balance	13,131,672	13,422,692
Shares, outstanding, beginning balance	13,131,672	13,422,692
Repurchase of common shares	(109,545)	(62,896)
Shares, Issued, Ending Balance	13,023,511	13,361,613
Shares, outstanding, ending balance	13,023,511	13,361,613
Common Stock [Member]
Class of Stock [Line Items]
Issuance of common shares	1,384	1,817

Shareholders' Equity (Schedul_2

Shareholders' Equity (Schedule Of Net Income (Loss) Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Line Items]
Net income to common shareholders	$ 1,025,184	$ 488,652
Adjustment of redeemable noncontrolling interests	(32,602)	13,473
Adjusted net income to common shareholders	$ 992,582	$ 502,125
Basic common shares outstanding	13,137	13,450
Diluted common shares outstanding	13,159	13,475
Earnings Per Share, Basic	$ 75.56	$ 37.33
Earnings Per Share, Diluted	$ 75.43	$ 37.26
Restricted Stock Units (RSUs) [Member]
Earnings Per Share [Line Items]
Dilutive potential common shares from restricted stock units and restricted stock	22	25