Markel (MKL) 10-K 24 Feb 25 2024 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2024	Feb. 05, 2025	Jun. 30, 2024
Cover [Abstract]
Document Type	10-K
Document Period End Date	Dec. 31, 2024
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction	false
Entity Shell Company	false
Document Annual Report	true
Document Transition Report	false
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Entity Central Index Key	0001096343
Current Fiscal Year End Date	--12-31
Entity Public Float			$ 20,072,000,000
Entity Common Stock, Shares Outstanding		12,770,003
Documents Incorporated by Reference	The portions of the registrant's Proxy Statement for the Annual Meeting of Shareholders scheduled to be held on May 21, 2025, referred to in Part III.
Auditor Name	KPMG LLP
Auditor Location	Richmond, VA
Auditor Firm ID	185

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2024	Dec. 31, 2023
ASSETS
Fixed maturity securities, available-for-sale (amortized cost of $16,457,723 in 2024 and $14,932,286 in 2023)		$ 15,745,539	$ 14,372,732
Equity securities (cost of $3,887,820 in 2024 and $3,497,071 in 2023)		11,784,521	9,577,871
Short-term investments, available-for-sale (estimated fair value approximates cost)		2,524,910	2,571,382
Total Investments		30,054,970	26,521,985
Cash and cash equivalents		3,692,667	3,747,060
Restricted cash and cash equivalents		499,581	584,974
Receivables		3,626,799	3,455,306
Reinsurance recoverables		11,604,844	9,235,501
Deferred policy acquisition costs		875,710	931,344
Prepaid reinsurance premiums		2,947,213	2,365,243
Goodwill	[1]	2,735,867	2,624,749
Intangible assets		1,459,620	1,588,684
Other assets		4,400,711	3,990,864
Total Assets		61,897,982	55,045,710
LIABILITIES AND EQUITY
Unpaid losses and loss adjustment expenses		26,633,094	23,483,321
Life and annuity benefits		583,273	649,054
Unearned premiums		7,063,956	6,642,426
Payables to insurance and reinsurance companies		1,434,901	1,037,722
Senior long-term debt and other debt (estimated fair value of $3,791,000 in 2024 and $3,353,000 in 2023)		4,330,341	3,779,796
Other liabilities		4,383,444	3,927,498
Total Liabilities		44,429,009	39,519,817
Redeemable noncontrolling interests		540,034	469,685
Commitments and contingencies
Shareholders' equity:
Preferred stock		591,891	591,891
Common stock		3,560,633	3,517,146
Retained earnings		13,380,456	11,353,101
Accumulated other comprehensive loss		(617,082)	(478,210)
Total Shareholders' Equity		16,915,898	14,983,928
Noncontrolling interests		13,041	72,280
Total Equity		16,928,939	15,056,208
Total Liabilities and Equity		$ 61,897,982	$ 55,045,710
[1] As of December 31, 2024 and 2023, goodwill was net of accumulated impairment losses of $190.6 million, of which $171.9 million was in other insurance operations and $18.7 million was in Markel Ventures.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Fixed maturity securities, available-for-sale (amortized cost of $16,457,723 in 2024 and $14,932,286 in 2023)	$ 16,457,723
Equity securities (cost of $3,887,820 in 2024 and $3,497,071 in 2023)	3,887,820	$ 3,497,071
Senior long-term debt and other debt (estimated fair value of $3,791,000 in 2024 and $3,353,000 in 2023)	$ 3,791,000	$ 3,353,000

Consolidated Statements Of Inco

Consolidated Statements Of Income (Loss) And Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
OPERATING REVENUES
Earned premiums	$ 8,432,412	$ 8,295,479	$ 7,587,792
Net investment income	920,496	734,532	446,755
Net investment gains (losses)	1,807,219	1,524,054	(1,595,733)
Products revenues	2,635,659	2,545,053	2,427,096
Services and other revenues	2,824,977	2,704,512	2,809,425
Total operating revenues	16,620,763	15,803,630	11,675,335
OPERATING EXPENSES
Losses and loss adjustment expenses	5,052,749	5,322,009	4,445,589
Underwriting, acquisition and insurance expenses	2,977,389	2,840,734	2,515,583
Products expenses	2,272,219	2,220,676	2,241,736
Services and other expenses	2,424,372	2,310,769	2,306,985
Amortization of intangible assets	181,472	180,614	178,778
Impairment of goodwill	0	0	80,000
Total Operating Expenses	12,908,201	12,874,802	11,768,671
Operating Income (Loss)	3,712,562	2,928,828	(93,336)
Interest expense	(204,300)	(185,077)	(196,062)
Net foreign exchange gains (losses)	129,438	(90,045)	137,832
Income (Loss) Before Income Taxes	3,637,700	2,653,706	(151,566)
Income tax (expense) benefit	(790,294)	(552,616)	48,209
Net Income (Loss)	2,847,406	2,101,090	(103,357)
Net income attributable to noncontrolling interests	(100,384)	(105,030)	(112,920)
Net Income (Loss) to Shareholders	2,747,022	1,996,060	(216,277)
Preferred stock dividends	(36,000)	(36,000)	(36,000)
Net Income (Loss) to Common Shareholders	2,711,022	1,960,060	(252,277)
OTHER COMPREHENSIVE INCOME (LOSS)
Net holding gains (losses) arising during the period	(148,302)	278,363	(1,199,736)
Reclassification adjustments for net losses included in net income (loss)	18,007	28,540	44,906
Change in net unrealized gains (losses) on available-for-sale investments, net of taxes	(130,295)	306,903	(1,154,830)
Change in discount rate for life and annuity benefits, net of taxes	252	(22,343)	149,874
Change in foreign currency translation adjustments, net of taxes	(3,765)	4,704	(9,259)
Change in net actuarial pension loss, net of taxes	(4,946)	74	24,730
Total Other Comprehensive Income (Loss)	(138,754)	289,338	(989,485)
Comprehensive Income (Loss)	2,708,652	2,390,428	(1,092,842)
Comprehensive income attributable to noncontrolling interests	(100,502)	(105,084)	(112,937)
Comprehensive Income (Loss) to Shareholders	$ 2,608,150	$ 2,285,344	$ (1,205,779)
NET INCOME (LOSS) PER COMMON SHARE
Basic (dollars per share)	$ 199.69	$ 147.32	$ (23.72)
Diluted (dollars per share)	$ 199.32	$ 146.98	$ (23.72)	[1]
[1] The impact of 33 thousand shares from restricted stock units and restricted stock was excluded from the computation of diluted net loss per common share for the year ended December 31, 2022 because the effect would have been anti-dilutive.

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 Income (Loss) [Member]	Noncontrolling Interests [Member]	Redeemable Noncontrolling Interests [Member]	Velocity [Member] Total Equity [Member]	Velocity [Member] Noncontrolling Interests [Member]	Volante [Member] Total Equity [Member]	Volante [Member] Noncontrolling Interests [Member]	Buckner HeavyLift Cranes [Member] Redeemable Noncontrolling Interests [Member]	Metromont LLC [Member] Redeemable Noncontrolling Interests [Member]
Balance at Dec. 31, 2021		$ 14,722,732	$ 14,699,872	$ 591,891	$ 3,441,079	$ 10,444,894	$ 222,008	$ 22,860
Balance, redeemable noncontrolling interests at Dec. 31, 2021									$ 461,378
Net income (loss)	$ (103,357)	(129,538)	(216,277)			(216,277)	0	86,739	26,181
Other comprehensive income (loss)	(989,485)	(989,502)	(989,502)			0	(989,502)	0	17
Comprehensive Income (Loss)	(1,092,842)	(1,119,040)	(1,205,779)					86,739	26,198
Repurchase of common stock		(290,796)	(290,796)	0	0	(290,796)	0	0	0
Preferred stock dividends		(36,000)	(36,000)	0	0	(36,000)	0	0	0
Equity awards expensed		41,684	41,684	0	41,684	0	0	0	0
Acquisitions		0	0	0	0	0	0	0							$ (22,485)
Adjustment of redeemable noncontrolling interests		(69,896)	(69,896)	0	0	(69,896)	0	0						$ 69,896
Dispositions			0	0	0	0	0		0	$ (22,059)	$ (22,059)	$ (3,490)	$ (3,490)
Redemption of Markel CATCo Re noncontrolling interests		(22,261)	0	0	0		0	(22,261)	0
Other		13,011	12,009	0	11,130	879	0	1,002	(11,833)
Balance, redeemable noncontrolling interests at Dec. 31, 2022									523,154
Balance at Dec. 31, 2022		13,213,885	13,151,094	591,891	3,493,893	9,832,804	(767,494)	62,791
Net income (loss)	2,101,090	2,068,196	1,996,060			1,996,060	0	72,136	32,894
Other comprehensive income (loss)	289,338	289,284	289,284			0	289,284	0	54
Comprehensive Income (Loss)	2,390,428	2,357,480	2,285,344					72,136	32,948
Repurchase of common stock		(445,479)	(445,479)	0	0	(445,479)	0	0	0
Preferred stock dividends	(36,000)	(36,000)	(36,000)	0	0	(36,000)	0	0	0
Equity awards expensed		35,787	35,787	0	35,787	0	0	0	0
Adjustment of redeemable noncontrolling interests		6,212	6,212	0	0	6,212	0	0	(6,212)
Purchase of noncontrolling interest		(12,144)	(12,144)	0	(12,144)	0	0	0	(51,227)
Redemption of Markel CATCo Re noncontrolling interests		(62,646)	0	0	0	0	0	(62,646)	0
Other		(887)	(886)	0	(390)	(496)	0	(1)	(28,978)
Balance, redeemable noncontrolling interests at Dec. 31, 2023	469,685								469,685
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
Net income (loss)	2,847,406	2,803,113	2,747,022			2,747,022	0	56,091	44,293
Other comprehensive income (loss)	(138,754)	(138,872)	(138,872)			0	(138,872)	0	118
Comprehensive Income (Loss)	2,708,652	2,664,241	2,608,150					56,091	44,411
Repurchase of common stock		(572,728)	(572,728)	0	0	(572,728)	0	0	0
Preferred stock dividends	(36,000)	(36,000)	(36,000)	0	0	(36,000)	0	0	0
Equity awards expensed		53,302	53,302	0	53,302	0	0	0	0
Adjustment of redeemable noncontrolling interests		(111,700)	(111,700)	0	0	(111,700)	0	0	111,700
Purchase of noncontrolling interest		(9,587)	(9,587)	0	(9,587)	0	0	0	(36,896)
Distributions to noncontrolling interests		0	0	0	0	0	0	0	(54,010)
Redemption of Markel CATCo Re noncontrolling interests		(117,227)	0	0	0	0	0	(117,227)	0
Other		2,430	533	0	(228)	761	0	1,897	5,144
Balance, redeemable noncontrolling interests at Dec. 31, 2024	540,034								$ 540,034
Balance at Dec. 31, 2024	$ 16,928,939	$ 16,928,939	$ 16,915,898	$ 591,891	$ 3,560,633	$ 13,380,456	$ (617,082)	$ 13,041

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
OPERATING ACTIVITIES
Net income (loss)	$ 2,847,406	$ 2,101,090	$ (103,357)
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income tax expense (benefit)	394,560	233,798	(282,325)
Depreciation and amortization expense	342,359	319,734	309,448
Net amortization of investment premium or discount	(123,522)	(59,810)	57,506
Net investment losses (gains)	(1,807,219)	(1,524,054)	1,595,733
Net foreign exchange losses (gains)	(129,438)	90,045	(137,832)
Gain on sale of businesses, net	0	(18,965)	(225,832)
Impairment of goodwill	0	0	80,000
Increase in receivables	(158,546)	(486,305)	(653,261)
Increase in reinsurance recoverables	(2,386,745)	(767,509)	(1,168,483)
Decrease (increase) in deferred policy acquisition costs	50,102	(1,602)	(140,630)
Increase in prepaid reinsurance premiums	(584,475)	(298,049)	(271,292)
Increase in unpaid losses and loss adjustment expenses	3,250,607	2,443,178	2,383,268
Decrease in life and annuity benefits	(38,981)	(48,327)	(44,693)
Increase in unearned premiums	448,238	400,017	886,393
Increase in payables to insurance and reinsurance companies	398,360	365,378	210,810
Other	91,300	38,188	213,989
Net Cash Provided By Operating Activities	2,594,006	2,786,807	2,709,442
INVESTING ACTIVITIES
Proceeds from sales, maturities, calls and prepayments of fixed maturity securities	2,068,755	2,126,586	1,152,335
Cost of fixed maturity securities purchased	(3,588,989)	(4,302,864)	(2,112,066)
Proceeds from sales of equity securities	177,254	298,582	242,010
Cost of equity securities purchased	(571,096)	(638,306)	(442,991)
Net change in short-term investments	151,972	202,930	(846,019)
Cost of other investments purchased	205,937	192,715	20,051
Additions to property and equipment	(254,991)	(258,619)	(254,712)
Acquisitions, net of cash acquired	(207,753)	(3,584)	(79,000)
Consolidation of Markel CATCo Re, net	0	0	629,955
Distributions to Markel CATCo Re noncontrolling interests for buy-out transaction	0	0	(169,380)
Proceeds from sale of businesses, net	0	41,302	201,370
Other	32,167	23,081	28,345
Net Cash Used By Investing Activities	(2,398,618)	(2,703,607)	(1,670,204)
FINANCING ACTIVITIES
Additions to senior long-term debt and other debt	1,434,205	624,972	1,034,052
Repayment of senior long-term debt and other debt	(896,749)	(949,636)	(1,255,005)
Repurchases of common stock	(572,728)	(445,479)	(290,796)
Dividends paid on preferred stock	(36,000)	(36,000)	(36,000)
Purchase of noncontrolling interests	(46,483)	(63,371)	(30)
Distributions to noncontrolling interests	(54,010)	(28,978)	(15,225)
Redemption of Markel CATCo Re noncontrolling interests	(117,227)	(88,997)	0
Other	(8,886)	(12,227)	(32,307)
Net Cash Used By Financing Activities	(297,878)	(999,716)	(595,311)
Effect of foreign currency rate changes on cash, cash equivalents, restricted cash and restricted cash equivalents	(37,296)	27,037	(103,361)
Increase (decrease) in cash, cash equivalents, restricted cash and restricted cash equivalents	(139,786)	(889,479)	340,566
Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of year	4,332,034	5,221,513	4,880,947
CASH, CASH EQUIVALENTS, RESTRICTED CASH AND RESTRICTED CASH EQUIVALENTS AT END OF YEAR	$ 4,192,248	$ 4,332,034	$ 5,221,513

Summary Of Significant Accounti

Summary Of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2024
Accounting Policies [Abstract]
Summary Of Significant Accounting Policies	1. 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 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 any 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. b) Use of Estimates. 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. Management periodically reviews its estimates and assumptions. Quarterly reviews include evaluating the adequacy of reserves for unpaid losses and loss adjustment expenses and contingencies. Estimates and assumptions for goodwill and intangible assets are reviewed in conjunction with an acquisition, and goodwill and indefinite-lived intangible assets are reassessed at least annually for impairment. Actual results may differ materially from the estimates and assumptions used in preparing the consolidated financial statements. c) Investments. Available-for-sale investments and equity securities are recorded at estimated fair value. Available-for-sale investments include fixed maturity securities and short-term investments. Fixed maturity securities include government and municipal bonds and mortgage-backed securities with original maturities of more than one year. Short-term investments are primarily comprised of treasury bills with original maturities of one year or less. Realized investment gains or losses on available-for-sale investments are included in net income. Realized gains or losses from sales of available-for-sale investments are derived using the first-in, first-out method on the trade date. Unrealized gains and losses on available-for-sale investments, net of income taxes, are included in other comprehensive income. The Company completes a detailed analysis each quarter to assess declines in the fair value of its available-for-sale investments. Any credit-related impairment losses on the Company's available-for-sale investments are recorded as an allowance, subject to reversal, and recognized in net income. Realized and unrealized gains and losses on equity securities are included in net income as net investment gains or losses. Premiums and discounts are amortized or accreted over the lives of the related fixed maturity securities as an adjustment to the yield using the effective interest method. Dividend and interest income are recognized when earned. Accrued interest receivable is excluded from both the estimated fair value and the amortized cost basis of available-for-sale securities and included within other assets on the Company's consolidated balance sheets. Any uncollectible accrued interest receivable is written off in the period it is deemed uncollectible. See note 4 and note 5 for further details regarding the Company's investment portfolio. d) Cash and Cash Equivalents. The Company considers all investments with original maturities of 90 days or less to be cash equivalents, with the exception of treasury bills, which are classified as short-term investments. The carrying value of the Company's cash and cash equivalents approximates fair value. e) Restricted Cash and Cash Equivalents. Cash and cash equivalents that are restricted as to withdrawal or use are recorded as restricted cash and cash equivalents. The carrying value of the Company's restricted cash and cash equivalents approximates fair value. f) Receivables. Receivables include amounts receivable from agents, brokers and insureds, which represent premiums that are both currently due and amounts not yet due on insurance and reinsurance policies. Premiums for insurance policies are generally due at inception. Premiums for reinsurance policies generally become due over the period of coverage based on the policy terms. Changes in the estimate of reinsurance premiums written will result in an adjustment to premiums receivable in the period they are determined. Receivables also include amounts receivable from contracts with customers, which represent the Company's unconditional right to consideration for satisfying the performance obligations outlined in the contract. The Company monitors credit risk associated with receivables, taking into consideration the fact that in certain instances in the Company's insurance operations credit risk may be reduced by the Company's right to offset loss obligations or unearned premiums against premiums receivable. An allowance is established for credit losses expected to be incurred over the life of the receivable, which is recorded net of this allowance. The allowance is charged to net income in the period the receivable is recorded and revised in subsequent periods to reflect changes in the Company's estimate of expected credit losses. See note 7 for further details regarding receivables. g) Reinsurance Recoverables. Amounts recoverable from reinsurers are estimated in a manner consistent with the claim liability associated with the reinsured business. The Company evaluates the financial condition of its reinsurers and monitors concentration of credit risk to minimize its exposure to significant losses from individual reinsurers. To further reduce credit exposure on reinsurance recoverables, the Company has received collateral, including letters of credit and trust accounts, from certain reinsurers. Cash collateral related to these reinsurance agreements is available, without restriction, when the Company pays losses covered by the reinsurance agreements. An allowance is established for credit losses expected to be incurred over the life of the reinsurance recoverable, which is recorded net of this allowance. The allowance is charged to net income in the period the recoverable is recorded and revised in subsequent periods to reflect changes in the Company's estimate of expected credit losses. As of December 31, 2024 and 2023, the allowance for credit losses associated with the Company's reinsurance recoverables was not material to the consolidated financial statements. h) Deferred Policy Acquisition Costs. Costs directly related to the acquisition of insurance premiums are deferred and amortized over the related policy period, generally one year. The Company only defers acquisition costs incurred that are directly related to the successful acquisition of new or renewal insurance contracts, including commissions to agents and brokers, salaries and benefits and premium taxes. Commissions received related to reinsurance premiums ceded are netted against broker commissions in determining acquisition costs eligible for deferral. To the extent that future policy revenues on existing policies are not adequate to cover related costs and expenses, deferred policy acquisition costs are charged to earnings. The Company does not consider anticipated investment income in determining whether a premium deficiency exists. See note 2(a) and (g) for further details regarding policy acquisition costs. i) Goodwill and Intangible Assets. Goodwill and intangible assets are recorded as a result of business acquisitions. Goodwill represents the excess of the amount paid to acquire a business over the net fair value of assets acquired and liabilities assumed at the date of acquisition. Indefinite-lived and other intangible assets are recorded at fair value as of the acquisition date. The determination of the fair value of certain assets acquired and liabilities assumed involves significant judgment and the use of valuation models and other estimates, which require assumptions that are inherently subjective. Goodwill and indefinite-lived intangible assets are tested for impairment at least annually. The Company completes an annual test during the fourth quarter of each year based upon the results of operations through September 30. Intangible assets with definite lives are amortized using the straight-line method over their estimated useful lives, generally five j) Equity Method Investments. The Company holds certain investments that are required to be accounted for under the equity method, whereby they initially are recorded at cost within other assets on the consolidated balance sheets and subsequently increased or decreased by the Company's proportionate share of the net income or loss of the investee and other transactions impacting the investee's equity. The Company records its proportionate share of net income or loss of the investee in services and other revenues. The Company records its proportionate share of other comprehensive income or loss of the investee as a component of other comprehensive income. Dividends or other equity distributions in excess of the Company's cumulative equity in earnings of the investee are recorded as a reduction of the investment. The Company reviews equity method investments for impairment when events or circumstances indicate that a decline in the fair value of the investment below its carrying value is other-than-temporary. See note 6 for further details regarding the Company's equity method investments. k) Property and Equipment. Property and equipment is maintained primarily by certain of the Company's Markel Ventures businesses and is stated at cost less accumulated depreciation. Depreciation of property and equipment is calculated using the straight-line method over the estimated useful lives of the respective assets. Property and equipment, net of accumulated depreciation, was $1.4 billion and $1.3 billion as of December 31, 2024 and 2023, respectively, and is included in other assets on the Company's consolidated balance sheets. l) Leases. The present value of future lease payments for the Company's leases with terms greater than 12 months is included on the consolidated balance sheets as lease liabilities and right-of-use lease assets within other liabilities and other assets, respectively. The Company's lease portfolio primarily consists of operating leases for real estate and equipment. Total expected lease payments are based on the lease payments specified in the contract and the stated term, including any options to extend or terminate that the Company is reasonably certain to exercise. The Company accounts for lease components and any associated non-lease components within a contract as a single lease component, and therefore allocates all of the expected lease payments to the lease component. The lease liability, which represents the Company's contractual obligation to make lease payments, is calculated based on the present value of expected lease payments over the remaining lease term, discounted using the Company's collateralized incremental borrowing rate at the lease commencement date. The lease liability is then adjusted for any prepaid rent, lease incentives received or capitalized initial direct costs to determine the lease asset, which represents the Company's right to use the underlying asset for the lease term. Total lease costs are primarily comprised of rental expense for operating leases, which is recognized on a straight line basis over the lease term. Rental expense attributable to the Company's underwriting operations is included in underwriting, acquisition and insurance expenses and rental expense attributable to the Company's other operations is included in products expenses and services and other expenses in the consolidated statements of income and comprehensive income. See note 9 for further details regarding leases. m) Inventories. Inventories are maintained at certain of the Company's Markel Ventures businesses and consist primarily of raw materials, work-in-process and finished goods. Inventories are generally valued based on the nature of the inventory, including the first-in-first-out, standard cost and specific identification methods, and stated at the lower of cost or net realizable value. Inventories were $631.5 million and $617.2 million as of December 31, 2024 and 2023, respectively, and are included in other assets on the Company's consolidated balance sheets. n) Redeemable Noncontrolling Interests. The Company owns controlling interests in various companies through its Markel Ventures operations. In some cases, the Company has the option to acquire the remaining equity interests, and the remaining equity interests have the option to sell their interests to the Company, in the future. The redemption value of the remaining equity interests is generally based on the respective company's earnings in specified periods preceding the redemption date. The redeemable noncontrolling interests are redeemable in 2025 or become redeemable between 2026 and 2032. The Company recognizes changes in the redemption value that exceed the carrying value of redeemable noncontrolling interests to retained earnings as if the balance sheet date was also the redemption date. Changes in the redemption value also result in an adjustment to net income to common shareholders in the calculation of basic and diluted net income per common share. See note 19 for further details regarding the calculation of basic and diluted net income per common share. o) Income Taxes. The Company records deferred income taxes to reflect the net tax effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and their tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in years in which those temporary differences are expected to be recovered or settled. Deferred tax assets are reduced by a valuation allowance when management believes it is more likely than not that some, or all, of the deferred tax assets will not be realized. The Company recognizes the tax benefit from an uncertain tax position taken or expected to be taken in income tax returns only if it is more likely than not that the tax position will be sustained upon examination by tax authorities, based on the technical merits of the position. Tax positions that meet the more likely than not threshold are then measured using a probability weighted approach, whereby the largest amount of tax benefit that is greater than 50% likely of being realized upon ultimate settlement is recognized. The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. See note 15 for further details regarding income taxes. p) Unpaid Losses and Loss Adjustment Expenses. Unpaid losses and loss adjustment expenses on the Company's property and casualty insurance business are based on evaluations of reported claims and estimates for losses and loss adjustment expenses incurred but not reported (IBNR). Estimates for losses and loss adjustment expenses incurred but not reported are based on reserve development studies, among other things. Recorded reserves are estimates, and the ultimate liability may be greater or less than the estimates. See note 11 for further details regarding unpaid losses and loss adjustment expenses. q) Life and Annuity Benefits. The Company has a run-off block of life and annuity reinsurance contracts that subject the Company to mortality, longevity and morbidity risks. The primary component of the Company's liabilities for life and annuity benefits is the present value of the liability for future policyholder benefits. The cash flow assumptions used to determine the policyholder benefit reserves are reviewed, and updated as necessary, at least annually. Interest accretion for the reserves is calculated using the discount rate locked-in at contract inception. Policy benefit reserves are remeasured each period using current discount rates, based on yields for upper-medium grade fixed maturity securities, with the impact of changes in the discount rate included in other comprehensive income, net of taxes. All other results attributable to the run-off of life and annuity reinsurance contracts are included in services and other revenues and services and other expenses in the consolidated statements of income and comprehensive income. Investment income earned on the investments that support the policy benefit reserves are included in net investment income. Because of the uncertainty in the assumptions used to estimate reserves for life and annuity benefit obligations and the long-term nature of these reinsurance contracts, the ultimate liability may be greater or less than the estimated liability. See note 13 for further details regarding life and annuity benefits. r) Revenue Recognition. Property and Casualty Premiums Insurance premiums written are generally recorded at the inception of a policy and earned on a pro rata basis over the policy period, typically one year. The cost of reinsurance ceded is initially recorded as prepaid reinsurance premiums and is amortized over the reinsurance contract period in proportion to the amount of insurance protection provided. Premiums ceded are netted against premiums written. For multi-year contracts where insurance premiums are payable in annual installments, written premiums are recorded at the inception of the contract based on management's best estimate of total premiums to be received. For contracts where the cedent has the ability to unilaterally commute or cancel coverage within the term of the policy, written premiums are generally recorded on an annual basis or up to the contract cancellation point. The remaining premiums are estimated and included as written at each successive anniversary date within the multi-year term. Assumed reinsurance premiums are recorded at the inception of each contract based upon contract terms and information received from cedents and brokers and are earned on a pro rata basis over the coverage period, or for multi-year contracts, in proportion with the underlying risk exposure to the extent there is variability in the exposure through the coverage period. Changes in reinsurance premium estimates are expected and may result in significant adjustments in any period. These estimates change over time as additional information regarding changes in underlying exposures is obtained. Any subsequent differences arising on such estimates are recorded as premiums written in the period they are determined and are earned on a pro rata basis over the coverage period, or immediately if the coverage period has ended. The Company uses the periodic method to account for assumed reinsurance from foreign reinsurers as a result of the sufficiency of the information provided by the reinsurer, which is consistent with its accounting for assumed reinsurance from U.S. reinsurers. Certain contracts that the Company writes provide for reinstatement of coverage. Reinstatement premiums are the premiums for the restoration of the insurance or reinsurance limit of a contract to its full amount after a loss occurrence by the insured or reinsured. The Company accrues for reinstatement premiums resulting from losses recorded. Such accruals are based upon contractual terms and management judgment is involved with respect to the amount of losses recorded. Changes in estimates of losses recorded on contracts with reinstatement premium features will result in changes in reinstatement premiums based on contractual terms. Reinstatement premiums are recognized as premiums written at the time losses are recorded and are generally earned on a pro rata basis over the remaining coverage period. Other Revenues Other revenues primarily relate to the Company's Markel Ventures, program services and insurance-linked securities (ILS) operations and consist of revenues from the sale of products and services. Revenues are recognized when, or as, control of the promised goods or services is transferred to the Company's customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. Contracts with customers generally have an original term of one year or less. For contracts with customers that have an original term greater than one year, the Company recognizes revenue at the amount for which it has a right to invoice for the products delivered or services performed. Certain customers may receive volume rebates or credits for products and services, which are accounted for as variable consideration. The Company estimates these amounts based on the expected amount to be provided to the customer and reduces revenues recognized by a corresponding amount. The Company does not expect significant changes to its estimates of variable consideration over the term of the contracts. Payment terms for products and services vary by the type of product or service offered and the location of the customer, and payment is typically received at or shortly after the point of sale. For certain products, the Company requires partial payment in the form of a deposit before the products are delivered to the customer, which is included in other liabilities on the Company's consolidated balance sheets. Through its Markel Ventures operations, the Company has several different businesses that manufacture or produce a variety of products, including ornamental plants, precast concrete, equipment used in baking systems, over-the-road transportation equipment, portable dredges, residential homes and flooring for the trucking industry. Most of the Company's product revenues are recognized when the products are shipped to the customer or the products arrive at the agreed upon destination with the end customer. Certain of the Company's products revenues are recognized based on percentage of completion. Some of the Company's contracts include multiple performance obligations. For such arrangements, revenues are allocated to each performance obligation based on the relative standalone selling price, which is derived from amounts stated in the contract. Through its Markel Ventures operations, the Company also has several different businesses that provide various types of services, including distribution of exterior building products, fire protection and life safety services and consulting services. Service revenues are generally recognized either at a point-in-time when services are provided or over the term of the contracts based on hours incurred or as services are provided. The Company's Markel Ventures operations also include certain businesses that earn revenues through the leasing of equipment. The revenues from these leases are generally recognized on a straight-line basis over the term of the lease. The Company's other revenues also include fronting fees, or ceding fees, which are based on the gross premiums written on behalf of general agent and capacity provider clients. Ceding fees are earned in a manner consistent with the recognition of the gross premiums earned on the underlying insurance policies, generally on a pro rata basis over the terms of the underlying policies reinsured. The Company's other revenues also include investment management fee income. Investment management fee income is recognized over the period in which investment management services are provided and is calculated and recognized monthly, based on either the net asset value of the accounts managed or gross premium volume for the underlying risks. For certain accounts, the Company is also entitled to participate, on a fixed-percentage basis, in any net income generated in excess of an agreed-upon threshold as established by the underlying investment management agreements. In general, net income is calculated at the end of each calendar year and incentive fees are payable annually. Incentive fee income is recognized at the conclusion of the contractual performance period, when the uncertainty related to performance has been resolved. See note 10 for further details regarding products, services and other revenues. s) Program Services. In connection with its program services business, the Company enters into contractual agreements with both producing general agents and reinsurers, whereby the general agents and reinsurers are typically obligated to each other for payment of insurance amounts, including premiums, commissions and losses. To the extent these funds are not the obligation of the Company and are settled directly between the general agent and the reinsurer, no receivables or payables are recorded for these amounts. All obligations of the Company's insurance subsidiaries owed to or on behalf of their policyholders are recorded by the Company and, to the extent appropriate, offsetting reinsurance recoverables are recorded. t) Foreign Currency Transactions. The U.S. Dollar is the Company's reporting currency and the primary functional currency of its foreign underwriting operations. The functional currencies of the Company's other foreign operations are the currencies of the primary economic environments in which the majority of their business is transacted. Foreign currency transaction gains and losses are the result of exchange rate changes on transactions denominated in currencies other than the functional currency at each foreign entity. Monetary assets and liabilities are remeasured to the functional currency at current exchange rates, with resulting gains and losses included in net foreign exchange gains within net income. Non-monetary assets and liabilities are remeasured to the functional currency at historic exchange rates. Available-for-sale securities are recorded at fair value with resulting gains and losses, including the portion attributable to movements in exchange rates, included in the change in net unrealized gains on available-for-sale investments, net of taxes within other comprehensive income. While the Company attempts to naturally hedge its exposure to foreign currency fluctuations by matching assets and liabilities in the same currencies, there is a financial statement mismatch between the gains or losses recorded in net income related to insurance reserves denominated in non-functional currencies and the gains or losses recorded in other comprehensive income related to the available-for-sale securities held in non-functional currencies supporting the reserves. Assets and liabilities of foreign operations denominated in a functional currency other than the U.S. Dollar are translated into the U.S. Dollar at current exchange rates, with resulting gains or losses included, net of taxes, in the change in foreign currency translation adjustments within other comprehensive income. u) Comprehensive Income. Comprehensive income represents all changes in equity that result from recognized transactions and other economic events during the period. Other comprehensive income refers to revenues, expenses, gains and losses that under U.S. GAAP are included in comprehensive income but excluded from net income, such as unrealized gains or losses on available-for-sale investments, changes in discount rate for life and annuity benefits, foreign currency translation adjustments and changes in net actuarial pension loss. See note 20 for further details regarding other comprehensive income. v) Net Income Per Common Share. Basic net income per common share is computed by dividing adjusted net income to shareholders by the weighted average number of common shares outstanding during the year. Diluted net income per common share is computed by dividing adjusted net income to shareholders by the sum of the weighted average number of common shares and dilutive potential common shares outstanding during the year. See note 19 for further details regarding the calculation of basic and diluted net income per common share. w) Variable Interest Entities. The Company determines whether it has relationships with entities defined as VIEs in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 810, Consolidation . Under this guidance, a VIE is consolidated by the variable interest holder that is determined to be the primary beneficiary. An entity in which the Company holds a variable interest is a VIE if any of the following conditions exist: (a) the total equity investment at risk is not sufficient to permit the entity to finance its activities without additional subordinated financial support, (b) as a group, the holders of equity investment at risk lack either the direct or indirect ability through voting rights or similar rights to make decisions about an entity's activities that most significantly impact the entity's economic performance or the obligation to absorb the expected losses or right to receive the expected residual returns, or (c) the voting rights of some investors are disproportionate to their obligation to absorb the expected losses of the entity, their rights to receive the expected residual returns of the entity, or both and substantially all of the entity's activities either involve or are conducted on behalf of an investor with disproportionately few voting rights. The primary beneficiary is defined as the variable interest holder that is determined to have the controlling financial interest as a result of having both (a) the power to direct the activities of a VIE that most significantly impact the economic performance of the VIE and (b) the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. The Company determines whether an entity is a VIE at the inception of its variable interest in the entity and upon the occurrence of certain reconsideration events. The Company continually reassesses whether it is the primary beneficiary of VIEs in which it holds a variable interest. See note 17 for further details regarding the Company's involvement with VIEs. x) Recent Accounting Pronouncements. Accounting Standards Adopted in 2024 In November 2023, the 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 became effective for the Company's 2024 Annual Report on Form 10-K and was applied using a retrospective approach that required recasting of all prior periods presented. The standard only impacts required disclosures and does not impact the Company's financial position, results of operations or cash flows. The ASU did not result in significant changes to the Company's reportable segment disclosures. See note 2 for the Company's segment disclosures. Accounting Standards Not Yet Adopted 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,

Segment Reporting Disclosures

Segment Reporting Disclosures	12 Months Ended
	Dec. 31, 2024
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Segment Reporting Disclosures	2. Segment Reporting Disclosures The Company has four reportable segments: Insurance, Reinsurance, Investing and Markel Ventures. The Company's chief operating decision maker is the chief executive officer The chief operating decision maker reviews the Company's ongoing underwriting operations on a global basis in the following two segments: Insurance and Reinsurance. In determining how to allocate resources and assess the performance of the Company's underwriting results, the chief operating decision maker considers many factors, including the nature of the insurance product sold, the type of account written and the type of customer served. The Insurance segment includes all direct business 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 insurance-linked securities businesses. 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 the Company's Investing segment include the Company's 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 and impairment of goodwill, both of which arise from purchase accounting for acquisitions. The chief operating decision maker does not consider these expenses in assessing the financial performance of, or allocating resources to, operating segments. These expenses are considered corporate expenses because they are not a cost of operating the underlying businesses. For the Company's 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 and impairment of goodwill. 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. The chief operating decision maker uses segment operating income to assess the performance of each segment and determine how to allocate capital. The chief operating decision maker allocates capital where he believes it will earn an appropriate return. 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 operations, including its program services and insurance-linked securities businesses. 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. Year Ended December 31, 2024 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures Other insurance operations Corporate Consolidated Earned premiums $ 7,407,643 $ 1,028,201 $ — $ — $ (3,432) $ — $ 8,432,412 Net investment income — — 913,478 7,018 — — 920,496 Net investment gains — — 1,807,219 — — — 1,807,219 Products revenues — — — 2,635,659 — — 2,635,659 Services and other revenues — — 52,253 2,477,419 295,305 — 2,824,977 Total operating revenues 7,407,643 1,028,201 2,772,950 5,120,096 291,873 — 16,620,763 Losses and loss adjustment expenses: Current accident year - attritional (4,704,219) (733,191) — — — — (5,437,410) Current accident year - catastrophe (67,169) (3,480) — — — — (70,649) Prior accident years 451,016 12,344 — — (8,050) — 455,310 Underwriting, acquisition and insurance expenses: Amortization of policy acquisition costs (1,501,829) (252,312) — — — — (1,754,141) Other underwriting expenses (1,163,557) (56,925) — — (2,766) — (1,223,248) Products expenses — — — (2,272,219) — — (2,272,219) Services and other expenses — — — (2,327,795) (96,577) — (2,424,372) Amortization of acquired intangible assets (181,472) (181,472) Operating income (loss) $ 421,885 $ (5,363) $ 2,772,950 $ 520,082 $ 184,480 $ (181,472) $ 3,712,562 Interest expense (204,300) Net foreign exchange gains 129,438 Income before income taxes $ 3,637,700 Year Ended December 31, 2023 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures Other insurance operations Corporate Consolidated Earned premiums $ 7,282,705 $ 1,014,294 $ — $ — $ (1,520) $ — $ 8,295,479 Net investment income — — 729,219 5,313 — — 734,532 Net investment gains — — 1,524,054 — — — 1,524,054 Products revenues — — — 2,545,053 — — 2,545,053 Services and other revenues — — (11,854) 2,434,715 281,651 — 2,704,512 Total operating revenues 7,282,705 1,014,294 2,241,419 4,985,081 280,131 — 15,803,630 Losses and loss adjustment expenses: Current accident year - attritional (4,651,173) (669,314) — — — — (5,320,487) Current accident year - catastrophe (39,572) (500) — — — — (40,072) Prior accident years 104,743 (57,081) — — (9,112) — 38,550 Underwriting, acquisition and insurance expenses: Amortization of policy acquisition costs (1,508,169) (255,501) — — — — (1,763,670) Other underwriting expenses (1,026,358) (51,163) — — 457 — (1,077,064) Products expenses — — — (2,220,676) — — (2,220,676) Services and other expenses — — — (2,244,527) (66,242) — (2,310,769) Amortization of acquired intangible assets (180,614) (180,614) Operating income (loss) $ 162,176 $ (19,265) $ 2,241,419 $ 519,878 $ 205,234 $ (180,614) $ 2,928,828 Interest expense (185,077) Net foreign exchange losses (90,045) Income before income taxes $ 2,653,706 Year Ended December 31, 2022 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures Other insurance operations Corporate Consolidated Earned premiums $ 6,528,263 $ 1,063,347 $ — $ — $ (3,818) $ — $ 7,587,792 Net investment income — — 445,846 909 — — 446,755 Net investment losses — — (1,595,733) — — — (1,595,733) Products revenues — — — 2,427,096 — — 2,427,096 Services and other revenues — — (17,661) 2,329,522 497,564 — 2,809,425 Total operating revenues 6,528,263 1,063,347 (1,167,548) 4,757,527 493,746 — 11,675,335 Losses and loss adjustment expenses: Current accident year - attritional (3,867,195) (663,903) — — — — (4,531,098) Current accident year - events (1) (69,230) (12,707) — — — — (81,937) Prior accident years 142,924 26,052 — — (1,530) — 167,446 Underwriting, acquisition and insurance expenses: Amortization of policy acquisition costs (1,375,539) (279,567) — — — — (1,655,106) Other underwriting expenses (809,352) (49,363) — — (1,762) — (860,477) Products expenses — — — (2,241,736) — — (2,241,736) Services and other expenses — — — (2,111,510) (195,475) — (2,306,985) Amortization of acquired intangible assets (178,778) (178,778) Impairment of goodwill (80,000) (80,000) Operating income (loss) $ 549,871 $ 83,859 $ (1,167,548) $ 404,281 $ 294,979 $ (258,778) $ (93,336) Interest expense (196,062) Net foreign exchange gains 137,832 Loss before income taxes $ (151,566) (1) Includes losses and loss adjustment expenses attributed to catastrophes and the Russia-Ukraine conflict. b) The following amounts attributable to the Markel Ventures segment are also reviewed, or included in measures reviewed, by the Company's chief operating decision maker. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Depreciation expense $ 122,125 $ 108,605 $ 102,055 Capital expenditures $ 177,075 $ 221,036 $ 225,230 c) The following table reconciles segment assets to the Company's consolidated balance sheets. December 31, (dollars in thousands) 2024 2023 Segment assets: Investing $ 34,272,049 $ 30,542,282 Underwriting 10,784,528 9,897,689 Markel Ventures 5,824,229 5,519,542 Total segment assets 50,880,806 45,959,513 Other insurance operations 11,017,176 9,086,197 Total assets $ 61,897,982 $ 55,045,710 d) The following table summarizes earned premiums by major product grouping within each underwriting segment. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Insurance segment: General liability $ 2,063,827 $ 2,128,317 $ 1,927,721 Professional liability 1,655,848 1,798,882 1,739,983 Marine and energy 747,004 688,591 585,885 Personal lines 625,542 538,816 489,648 Property 609,453 532,337 428,563 Programs 576,444 509,866 384,952 Workers' compensation 374,371 393,011 385,054 Credit and surety 248,001 219,542 193,701 Other products 507,153 473,343 392,756 Total Insurance 7,407,643 7,282,705 6,528,263 Reinsurance segment: General liability 382,151 368,376 382,482 Professional liability 371,198 388,610 398,839 Specialty 269,021 245,126 275,033 Property 5,831 12,182 6,993 Total Reinsurance 1,028,201 1,014,294 1,063,347 Other (3,432) (1,520) (3,818) Total earned premiums $ 8,432,412 $ 8,295,479 $ 7,587,792 The Company does not manage products at this level of aggregation as it offers a diverse portfolio of products and manages these products in more disaggregated groupings within each underwriting segment. During the years ended December 31, 2024, 2023 and 2022, 75% of gross premiums written in the Company's underwriting segments were attributed to risks or cedents located in the United States. Substantially all of the gross premiums written in the Company's program services and ILS fronting operations during 2024, 2023 and 2022 were attributed to risks located in the United States. Most of the gross written premiums in the Company's underwriting operations are placed through insurance and reinsurance brokers. The following table summarizes the percentage of gross written premiums placed by the top five independent brokers within the Company's underwriting operations, Insurance segment and Reinsurance segment. The top five independent brokers may vary among the segments and from year to year. Years Ended December 31, 2024 2023 2022 Insurance segment 32 % 33 % 34 % Reinsurance segment 90 % 95 % 99 % Total underwriting 38 % 37 % 40 % e) The following table summarizes gross and net written premiums by segment, including a reconciliation to total underwriting and consolidated amounts. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Gross written premium: Insurance segment $ 9,400,316 $ 9,217,150 $ 8,606,700 Reinsurance segment 1,150,780 1,046,539 1,229,851 Other underwriting 777 13,943 10,987 Total underwriting 10,551,873 10,277,632 9,847,538 Program services and ILS fronting 4,942,758 3,724,605 3,354,144 Total $ 15,494,631 $ 14,002,237 $ 13,201,682 Net written premium: Insurance segment $ 7,260,089 $ 7,432,062 $ 7,040,176 Reinsurance segment 1,039,372 967,799 1,167,312 Other underwriting 290 (1,073) (115) Total underwriting 8,299,751 8,398,788 8,207,373 Program services and ILS fronting (3,576) (1,213) (3,983) Total $ 8,296,175 $ 8,397,575 $ 8,203,390 f) The following table summarizes deferred policy acquisition costs, unearned premiums and unpaid losses and loss adjustment expenses by segment, including a reconciliation to total underwriting and consolidated amounts. (dollars in thousands) Deferred Policy Unearned Unpaid Losses and December 31, 2024 Insurance segment $ 648,969 $ 4,283,879 $ 16,073,355 Reinsurance segment 226,741 933,329 3,870,059 Other underwriting — 1,558 149,522 Total underwriting 875,710 5,218,766 20,092,936 Program services and ILS fronting — 1,845,190 6,515,153 Markel CATCo Re (see note 17) — — 25,005 Total $ 875,710 $ 7,063,956 $ 26,633,094 December 31, 2023 Insurance segment $ 708,128 $ 4,307,704 $ 14,221,258 Reinsurance segment 223,216 901,138 3,726,472 Other underwriting — 7,488 165,071 Total underwriting 931,344 5,216,330 18,112,801 Program services and ILS fronting — 1,426,096 5,185,553 Markel CATCo Re (see note 17) — — 184,967 Total $ 931,344 $ 6,642,426 $ 23,483,321 g) The following table summarizes total products revenues and services and other revenues by major product and service grouping within the Company's Markel Ventures segment. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Products: Consumer and building $ 1,606,353 $ 1,474,499 $ 1,510,130 Transportation-related 584,200 667,040 612,467 Equipment manufacturing 445,106 403,514 304,499 Total products revenues 2,635,659 2,545,053 2,427,096 Services and other: Construction 2,089,280 2,042,326 1,910,403 Consulting 283,343 297,115 326,549 Other 104,796 95,274 92,570 Total services and other revenues 2,477,419 2,434,715 2,329,522 Total products revenues and services and other revenues $ 5,113,078 $ 4,979,768 $ 4,756,618 The Company does not manage the Markel Ventures portfolio of businesses at this level of aggregation due to the distinct characteristics of each business and the autonomy with which each business operates. The Company's chief operating decision maker reviews and assesses the performance of the Markel Ventures businesses in the aggregate at the Markel Ventures segment level, while individual management teams are responsible for developing strategic initiatives, managing day-to-day operations and making investment and capital allocation decisions for their respective companies. During the years ended December 31, 2024, 2023 and 2022, 94%, 95%, and 96%, respectively, of Markel Ventures segment revenues were attributable to U.S. operations.

Acquisitions and Dispositions

Acquisitions and Dispositions	12 Months Ended
	Dec. 31, 2024
Business combinations, Asset acquisition and Disposition [Abstract]
Acquisitions and Dispositions	3. Acquisitions and Dispositions Educational Partners International In September 2024, the Company acquired a 68% ownership interest in Educational Partners International (EPI), a company that sponsors international teachers for placements in schools in the U.S. Total consideration for the Company's investment was $167.7 million. Through December 2024, the Company's investment was accounted for under the equity method, as the Company did not have control over the business due to regulatory approval that was still pending. The Company's proportionate share of earnings attributed to its investment in EPI is included in the Company's Markel Ventures segment. In January 2025, the Company received regulatory approval that resulted in the Company gaining control over EPI. The Company will consolidate EPI and perform a purchase price allocation for the acquisition in the first quarter of 2025. Valor Environmental In June 2024, the Company acquired 98% of Valor Environmental (Valor), an environmental services company providing erosion control and related services to commercial development sites and homebuilders throughout the United States. The Company has the option to acquire the remaining equity interests and the remaining equity holders have the option to sell their interests to the Company in the future. Total consideration for the transaction was $156.4 million, all of which was cash. The purchase price was preliminarily allocated to the acquired assets and liabilities of Valor based on estimated fair value at the acquisition date. The Company recognized goodwill of $107.5 million and intangible assets of $49.0 million, which included customer relationships, trade names and other intangible assets. Goodwill is primarily attributable to expected future earnings and cash flow potential of Valor, and it is not expected to be deductible for income tax purposes. Results attributable to Valor are included in the Company's Markel Ventures segment. The Company has not completed the process of determining the fair value of the assets acquired and liabilities assumed. As a result, the fair value recorded for these items is a provisional estimate and is subject to adjustment. Once completed, any adjustments resulting from the valuations may impact the individual amounts recorded for assets acquired and liabilities assumed, as well as the residual goodwill. Volante In October 2022, the Company sold its controlling interest in its Volante managing general agent companies (Volante) for total consideration of $181.9 million, of which $155.6 million was cash. This transaction resulted in a gain of $118.5 million that was included in services and other revenue. Volante underwrites and administers specialty insurance and reinsurance policies and provides delegated underwriting services to third-party providers of insurance capital. Velocity In February 2022, the Company sold the majority of its controlling interest in its Velocity managing general agent companies (Velocity) for total cash consideration of $181.3 million, which resulted in a gain of $107.3 million that was included in services and other revenues. The Company retained a minority interest in Velocity.

Investments

Investments	12 Months Ended
	Dec. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Investments	4. Investments a) The following tables summarize the Company's available-for-sale investments. Agency 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. December 31, 2024 (dollars in thousands) Amortized Gross Gross Estimated Fixed maturity securities: U.S. Treasury securities $ 5,147,365 $ 8,962 $ (68,469) $ 5,087,858 U.S. government-sponsored enterprises 1,445,171 2,976 (101,911) 1,346,236 Obligations of states, municipalities and political subdivisions 3,813,146 5,866 (199,520) 3,619,492 Foreign governments, agencies and supranationals 2,909,561 4,264 (207,302) 2,706,523 Agency mortgage-backed securities 2,771,589 2,096 (123,872) 2,649,813 Non-agency mortgage-backed securities 122,373 — (4,343) 118,030 Corporate and university bonds 248,518 76 (31,007) 217,587 Total fixed maturity securities 16,457,723 24,240 (736,424) 15,745,539 Short-term investments 2,530,941 548 (6,579) 2,524,910 Investments, available-for-sale $ 18,988,664 $ 24,788 $ (743,003) $ 18,270,449 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, agencies and supranationals 2,554,874 34,352 (142,008) 2,447,218 Agency mortgage-backed securities 2,507,682 8,939 (135,611) 2,381,010 Non-agency mortgage-backed securities 355,673 — (22,603) 333,070 Corporate and university bonds 281,242 141 (26,781) 254,602 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. December 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 $ 1,593,711 $ (27,213) $ 1,444,869 $ (41,256) $ 3,038,580 $ (68,469) U.S. government-sponsored enterprises 415,333 (10,938) 691,781 (90,973) 1,107,114 (101,911) Obligations of states, municipalities and political subdivisions 1,133,275 (21,242) 2,024,298 (178,278) 3,157,573 (199,520) Foreign governments, agencies and supranationals 1,056,877 (29,890) 1,246,215 (177,412) 2,303,092 (207,302) Agency mortgage-backed securities 757,562 (13,880) 1,710,436 (109,992) 2,467,998 (123,872) Non-agency mortgage-backed securities — — 118,030 (4,343) 118,030 (4,343) Corporate and university bonds 2,107 (137) 212,404 (30,870) 214,511 (31,007) Total fixed maturity securities 4,958,865 (103,300) 7,448,033 (633,124) 12,406,898 (736,424) Short-term investments 163,503 (6,579) — — 163,503 (6,579) Total $ 5,122,368 $ (109,879) $ 7,448,033 $ (633,124) $ 12,570,401 $ (743,003) At December 31, 2024, the Company held 1,485 available-for-sale securities in an unrealized loss position with a total estimated fair value of $12.6 billion and gross unrealized losses of $743.0 million. Of these 1,485 securities, 966 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $7.4 billion and gross unrealized losses of $633.1 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, agencies and supranationals 83,396 (394) 1,492,912 (141,614) 1,576,308 (142,008) Agency mortgage-backed securities 189,977 (1,872) 1,889,272 (133,739) 2,079,249 (135,611) Non-agency mortgage-backed securities — — 333,070 (22,603) 333,070 (22,603) Corporate and university bonds — — 236,205 (26,781) 236,205 (26,781) 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 December 31, 2024 or 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 December 31, 2024 are shown below by contractual maturity. (dollars in thousands) Amortized Estimated Due in one year or less $ 1,593,149 $ 1,571,022 Due after one year through five years 6,071,013 5,901,682 Due after five years through ten years 4,647,538 4,406,225 Due after ten years 1,252,061 1,098,767 13,563,761 12,977,696 Mortgage-backed securities 2,893,962 2,767,843 Total fixed maturity securities $ 16,457,723 $ 15,745,539 Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalties, and the holders may have the right to put the securities back to the issuer. Based on expected maturities, the estimated average duration of fixed maturity securities at December 31, 2024 was 3.9 years . d) The following table presents the components of net investment income. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Interest: Fixed maturity securities $ 510,044 $ 383,022 $ 294,417 Short-term investments 124,575 106,747 33,493 Cash and cash equivalents and restricted cash and cash equivalents 161,488 145,074 28,890 Dividends on equity securities 142,367 116,911 107,213 938,474 751,754 464,013 Investment expenses (17,978) (17,222) (17,258) Net investment income $ 920,496 $ 734,532 $ 446,755 e) The following table presents the components of net investment gains (losses) included in net income (loss) and the pre-tax 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. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Fixed maturity securities, short-term investments and other investments: Net realized investment gains (losses) $ 4,423 $ (42,177) $ (40,983) Equity securities: Change in fair value of securities sold during the period (14,966) 34,684 (14,884) Change in fair value of securities held at the end of the period 1,817,762 1,531,547 (1,539,866) Total change in fair value 1,802,796 1,566,231 (1,554,750) Net investment gains (losses) $ 1,807,219 $ 1,524,054 $ (1,595,733) Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss): Fixed maturity securities $ (152,630) $ 389,498 $ (1,474,890) Short-term investments (12,793) 1,060 11,014 Net increase (decrease) $ (165,423) $ 390,558 $ (1,463,876) f) Total restricted assets are included on the Company's consolidated balance sheets as follows. December 31, (dollars in thousands) 2024 2023 Fixed maturity securities $ 3,027,863 $ 3,102,899 Equity securities 915,242 1,004,347 Short-term investments 704,201 807,138 Restricted cash and cash equivalents 499,581 584,974 Total $ 5,146,887 $ 5,499,358 The following table presents the components of restricted assets. December 31, (dollars in thousands) 2024 2023 Assets held in trust or on deposit to support underwriting activities $ 4,727,799 $ 5,048,857 Assets pledged as security for letters of credit 419,088 450,501 Total $ 5,146,887 $ 5,499,358 g) At December 31, 2024 and 2023, investments in securities issued by the U.S. Treasury, U.S. government agencies and U.S. government-sponsored enterprises were the only investments in any one issuer that exceeded 10% of shareholders' equity.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements [Text Block]	5. 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, agency, and supranational bonds, mortgage-backed securities and corporate and university 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 and university bonds and obligations of foreign governments, agencies and supranationals include reported trades, benchmark yields, issuer spreads, bids, offers, credit information and estimated cash flows. Significant inputs used to determine the fair value of 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. December 31, 2024 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments: Fixed maturity securities, available-for-sale: U.S. Treasury securities $ — $ 5,087,858 $ — $ 5,087,858 U.S. government-sponsored enterprises — 1,346,236 — 1,346,236 Obligations of states, municipalities and political subdivisions — 3,619,492 — 3,619,492 Foreign governments, agencies, and supranationals — 2,706,523 — 2,706,523 Agency mortgage-backed securities — 2,649,813 — 2,649,813 Non-agency mortgage-backed securities — 118,030 — 118,030 Corporate and university bonds — 217,587 — 217,587 Total fixed maturity securities, available-for-sale — 15,745,539 — 15,745,539 Equity securities: Insurance, banks and other financial institutions 4,968,736 — 1,384 4,970,120 Industrial, consumer and all other 6,814,401 — — 6,814,401 Total equity securities 11,783,137 — 1,384 11,784,521 Short-term investments, available-for-sale 2,363,736 161,174 — 2,524,910 Total investments $ 14,146,873 $ 15,906,713 $ 1,384 $ 30,054,970 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, agencies, and supranationals — 2,447,218 — 2,447,218 Agency mortgage-backed securities — 2,381,010 — 2,381,010 Non-agency mortgage-backed securities — 333,070 — 333,070 Corporate and university bonds — 254,602 — 254,602 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 Except as disclosed in note 3, the Company did not have any assets or liabilities measured at fair value on a non-recurring basis during the years ended December 31, 2024 and 2023.

Equity Method Investments

Equity Method Investments	12 Months Ended
	Dec. 31, 2024
Equity Method Investments [Abstract]
Equity Method Investments Disclosure [Text Block]	6. Equity Method Investments The Company's equity method investments, which are included in other assets on the consolidated balance sheets, totaled $862.5 million and $605.9 million as of December 31, 2024 and 2023, respectively. As of December 31, 2024, the Company's equity method investments included its 2024 investment in EPI. See note 3. The Company's proportionate share of earnings in its equity method investments was income of $58.7 million for the year ended December 31, 2024 and losses of $2.1 million and $22.9 million for the years ended December 31, 2023 and 2022, respectively. Hagerty, Inc. 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 December 31, 2024 and 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 December 31, 2024 and 2023, the carrying value of the Company's investment in Hagerty was $264.7 million and $237.4 million, respectively. As of December 31, 2024 and 2023, the estimated value of the Company's investment, based on the closing stock price of Hagerty's Class A common shares, was $753.7 million and $608.4 million, respectively. See note 18 for further details regarding related party transactions with Hagerty.

Receivables

Receivables	12 Months Ended
	Dec. 31, 2024
Receivables [Abstract]
Receivables	7. Receivables The following table presents the components of receivables. December 31, (dollars in thousands) 2024 2023 Insurance Amounts receivable from agents, brokers and insureds $ 2,870,719 $ 2,686,199 Other insurance receivables 124,258 117,436 Markel Ventures 638,480 657,156 Other 26,651 25,604 3,660,108 3,486,395 Allowance for credit losses (33,309) (31,089) Receivables $ 3,626,799 $ 3,455,306

Goodwill And Intangible Assets

Goodwill And Intangible Assets	12 Months Ended
	Dec. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill And Intangible Assets	8. Goodwill and Intangible Assets The following table presents a rollforward of the components of goodwill by reportable segment. (dollars in thousands) Insurance Reinsurance Markel Ventures Other insurance operations (1) Total January 1, 2023 $ 771,628 $ 122,745 $ 1,153,909 $ 590,556 $ 2,638,838 Adjustments to preliminary purchase price allocation — — (16,752) — (16,752) Foreign currency movements and other adjustments 1,195 — 497 971 2,663 December 31, 2023 (2) $ 772,823 $ 122,745 $ 1,137,654 $ 591,527 $ 2,624,749 Acquisitions (note 3) — — 114,589 — 114,589 Foreign currency movements and other adjustments (3,247) — (434) 210 (3,471) December 31, 2024 (2) $ 769,576 $ 122,745 $ 1,251,809 $ 591,737 $ 2,735,867 (1) Amounts included in other insurance operations reflect the Company's operations that are not included in a reportable segment and are primarily related to the Company's program services and insurance-linked securities operations. (2) As of December 31, 2024 and 2023, goodwill was net of accumulated impairment losses of $190.6 million, of which $171.9 million was in other insurance operations and $18.7 million was in Markel Ventures. The Company completed its annual tests for goodwill and indefinite-lived intangible asset impairment as of October 1, 2024 based upon results of operations through September 30, 2024. See note 1 for further details regarding impairment testing. There was no impairment of goodwill during 2024 or 2023 and no impairment of indefinite-lived intangible assets during 2024, 2023 or 2022. For the year ended December 31, 2022, impairment of goodwill was $80.0 million, which was attributable to the Company's Nephila ILS operations, which are a component of the Company's other insurance operations. Subsequent to the acquisition of Nephila in 2018, through 2022, investment performance in the broader ILS market was adversely impacted by consecutive years of elevated catastrophe losses. These events, as well as volatility in the capital markets, impacted investor decisions around allocation of capital to ILS, which in turn impacted capital raises and redemptions within the funds Nephila manages. As a result, the Company performed a quantitative impairment assessment for the Nephila reporting unit in 2022. The Company estimated the fair value of the Nephila reporting unit primarily using an income approach based on a discounted cash flow model. The discount rates used to determine the fair value estimates were developed based on a capital asset pricing model using market-based inputs, as well as an assessment of the inherent risk in projected future cash flows. As a result of the assessment, the Company recorded an impairment of goodwill attributable to Nephila totaling $80.0 million, reducing the goodwill of the Nephila reporting unit to $221.8 million. The Company also evaluated the intangible assets within the Nephila reporting unit for impairment in 2022 and determined they were not impaired. The following table presents a rollforward of net intangible assets by reportable segment. (dollars in thousands) Underwriting (1) Markel Ventures Other insurance operations (2) Total January 1, 2023 $ 362,322 $ 796,297 $ 588,845 $ 1,747,464 Dispositions — — (2,000) (2,000) Amortization of acquired intangible assets (37,076) (82,370) (61,168) (180,614) Adjustments to preliminary purchase price allocation — 22,671 — 22,671 Foreign currency movements and other adjustments 98 119 946 1,163 December 31, 2023 $ 325,344 $ 736,717 $ 526,623 $ 1,588,684 Acquisitions (note 3) — 52,909 — 52,909 Amortization of acquired intangible assets (37,276) (81,317) (62,879) (181,472) Foreign currency movements and other adjustments (117) 154 (538) (501) December 31, 2024 $ 287,951 $ 708,463 $ 463,206 $ 1,459,620 (1) Amounts included in Underwriting reflect the intangible assets associated with the Company's underwriting segments, which are not allocated between the Insurance and Reinsurance segments. (2) Amounts included in other insurance operations reflect the Company's operations that are not included in a reportable segment and are primarily related to the Company's program services and insurance-linked securities operations. Amortization of acquired intangible assets is estimated to be $172.7 million for 2025, $165.5 million for 2026, $154.9 million for 2027, $146.1 million for 2028 and $142.0 million for 2029. Indefinite-lived intangible assets were $90.4 million at December 31, 2024 and 2023. The following table presents the components of intangible assets. December 31, 2024 2023 (dollars in thousands) Gross Accumulated Gross Accumulated Customer relationships $ 1,488,796 $ (699,550) $ 1,450,503 $ (600,724) Investment management agreements 464,000 (178,727) 464,000 (149,560) Broker and agent relationships 295,694 (182,139) 297,693 (168,586) Trade names 305,381 (157,494) 293,270 (138,040) Technology 113,187 (107,727) 113,248 (100,781) Insurance licenses 72,333 — 72,333 — Other 159,603 (113,737) 169,681 (114,353) Total $ 2,898,994 $ (1,439,374) $ 2,860,728 $ (1,272,044)

Leases

Leases	12 Months Ended
	Dec. 31, 2024
Leases [Abstract]
Leases [Text Block]	9. Leases The Company's leases primarily consist of operating leases for real estate and equipment and have remaining terms of up to 18 years. Total lease costs for operating leases were $169.0 million, $148.4 million and $126.3 million for the years ended December 31, 2024, 2023 and 2022, respectively. The following table summarizes details for the Company's operating leases recorded on the consolidated balance sheets. December 31, (dollars in thousands) 2024 2023 Right-of-use lease assets $ 681,405 $ 628,833 Lease liabilities $ 723,924 $ 657,217 Weighted average remaining lease term 9.0 years 9.8 years Weighted average discount rate 4.3 % 5.2 % During the years ended December 31, 2024, 2023 and 2022, the Company obtained operating right-of-use lease assets of $111.3 million, $130.2 million and $64.4 million, respectively, in exchange for operating lease obligations. The following table summarizes maturities of the Company's operating lease liabilities as of December 31, 2024, which reconciles to total operating lease liabilities included in other liabilities on the Company's consolidated balance sheet. Years Ending December 31, (dollars in thousands) 2025 $ 130,943 2026 116,324 2027 100,927 2028 88,473 2029 77,206 2030 and thereafter 368,468 Total lease payments 882,341 Less imputed interest (158,417) Total operating lease liabilities $ 723,924

Products, Services and Other Re

Products, Services and Other Revenues	12 Months Ended
	Dec. 31, 2024
Revenue from Contract with Customer [Abstract]
Products, Services and Other Revenues	10. Products, Services and Other Revenues The following table presents revenues from contracts with customers by type, all of which are included in products revenues and services and other revenues in the consolidated statements of income (loss) and comprehensive income (loss), along with a reconciliation to total products revenues and services and other revenues. Years Ended December 31, 2024 2023 2022 (dollars in thousands) Markel Ventures Other Total Markel Ventures Other Total Markel Ventures Other Total Products $ 2,607,581 $ — $ 2,607,581 $ 2,487,054 $ — $ 2,487,054 $ 2,379,399 $ — $ 2,379,399 Services 2,315,822 10,193 2,326,015 2,262,861 10,341 2,273,202 2,184,196 43,875 2,228,071 Management fees — 97,226 97,226 — 99,509 99,509 — 79,209 79,209 Total revenues from contracts with customers 4,923,403 107,419 5,030,822 4,749,915 109,850 4,859,765 4,563,595 123,084 4,686,679 Leasing revenues 176,293 — 176,293 188,904 — 188,904 157,552 — 157,552 Fronting fees — 187,480 187,480 — 154,838 154,838 — 147,612 147,612 Equity method and other investments income (loss) 6,577 52,253 58,830 (1,744) (11,854) (13,598) 2,541 (17,661) (15,120) Disposition gains — — — — 16,923 16,923 — 225,828 225,828 Other 6,805 406 7,211 42,693 40 42,733 32,930 1,040 33,970 Total $ 5,113,078 $ 347,558 $ 5,460,636 $ 4,979,768 $ 269,797 $ 5,249,565 $ 4,756,618 $ 479,903 $ 5,236,521

Unpaid Losses And Loss Adjustme

Unpaid Losses And Loss Adjustment Expenses	12 Months Ended
	Dec. 31, 2024
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Unpaid Losses And Loss Adjustment Expenses	11. Unpaid Losses and Loss Adjustment Expenses a) The following table presents a reconciliation of consolidated beginning and ending reserves for losses and loss adjustment expenses. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Gross reserves for losses and loss adjustment expenses, beginning of year $ 23,483,321 $ 20,947,898 $ 18,178,894 Reinsurance recoverables on unpaid losses, beginning of year 8,820,567 7,994,884 6,876,317 Net reserves for losses and loss adjustment expenses, beginning of year 14,662,754 12,953,014 11,302,577 Effect of foreign currency rate changes on beginning of year balance (78,702) 70,344 (160,622) Adjusted net reserves for losses and loss adjustment expenses, beginning of year 14,584,052 13,023,358 11,141,955 Incurred losses and loss adjustment expenses: Current accident year 5,508,059 5,360,559 4,613,035 Prior accident years (455,310) (38,550) (167,446) Total incurred losses and loss adjustment expenses 5,052,749 5,322,009 4,445,589 Payments: Current accident year 720,178 729,895 580,537 Prior accident years 3,239,999 2,663,165 2,396,446 Total payments 3,960,177 3,393,060 2,976,983 Effect of foreign currency rate changes on current year activity (3,934) (1,532) (5,468) Change in net reserves for losses and loss adjustment expenses of Markel CATCo Re (see note 17) (159,963) (162,954) 347,921 Reinsurance recoverable on retroactive reinsurance transactions — (125,067) — Net reserves for losses and loss adjustment expenses, end of year 15,512,727 14,662,754 12,953,014 Reinsurance recoverables on unpaid losses, end of year 11,120,367 8,820,567 7,994,884 Gross reserves for losses and loss adjustment expenses, end of year $ 26,633,094 $ 23,483,321 $ 20,947,898 In 2024, current accident year losses and loss adjustment expenses included $70.6 million of net losses and loss adjustment expenses attributed to Hurricane Helene and Hurricane Milton. These losses and loss adjustment expenses were net of ceded losses of $60.4 million. In 2024, the Company, through its program services operations, entered into a retroactive reinsurance contract on behalf of a third-party capacity provider under which it assumed a layer of loss reserves for a portfolio of casualty policies that were concurrently ceded to the third-party capacity provider. As a result of these transactions, the Company recorded $302.6 million of gross losses and loss adjustment expenses and $302.6 million of corresponding reinsurance recoverables. The transactions had no impact on the Company's net reserves for losses and loss adjustment expenses. In 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 (U.K.) 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. In 2023, current accident year losses and loss adjustment expenses included $40.1 million of net losses and loss adjustment expenses attributed to the Hawaiian wildfires and Hurricane Idalia. These losses and loss adjustment expenses were net of ceded losses of $9.3 million. In 2022, current accident year losses and loss adjustment expenses included $46.2 million of net losses and loss adjustment expenses attributed to Hurricane Ian. These losses and loss adjustment expenses were net of ceded losses of $115.3 million. In 2022, current accident year losses and loss adjustment expenses also included $35.7 million of net losses and loss adjustment expenses attributed to the Russia-Ukraine conflict. These losses and loss adjustment expenses were net of ceded losses of $44.3 million. b) Reserving Methodology The Company uses a variety of techniques to establish liabilities for unpaid losses and loss adjustment expenses based upon estimates of the ultimate amounts payable. The Company maintains reserves for specific claims incurred and reported (case reserves) and reserves for claims incurred but not reported (IBNR reserves), which include expected development on reported claims. The Company does not discount its reserves for losses and loss adjustment expenses to reflect estimated present value. There is normally a time lag between when a loss event occurs and when it is reported to the Company, and some claims may not be reported for many years. As a result, the liability for unpaid losses and loss adjustment expenses includes significant estimates for IBNR claims. The actuarial methods that the Company uses to estimate losses have been designed to address the lag in loss reporting as well as the delay in obtaining information that would allow the Company to more accurately estimate future payments. The reporting lag can be more pronounced in reinsurance contracts than in the insurance contracts due to a time lag between cedents establishing case reserves or re-estimating their reserves and notifying the Company of those new or revised case reserves. On reinsurance transactions, the reporting lag will generally be 60 to 90 days after the end of a reporting period, but can be longer in some cases. There may also be a more pronounced reporting lag on insurance contracts for which the Company is not the primary insurer and participates only in excess layers of loss. Based on the experience of the Company's actuaries and management, the Company selects loss development factors and trending techniques to mitigate the difficulties caused by reporting lags. At least annually, the Company evaluates its loss development factors and trending assumptions using its own loss data, as well as cedent-specific and industry data, and updates them as needed. IBNR reserves are based on the estimated ultimate cost of settling claims using past experience adjusted for current trends and any other factors that would modify past experience. IBNR reserves are calculated by subtracting paid losses and loss adjustment expenses and case reserves from estimated ultimate losses and loss adjustment expenses. IBNR reserves were 71% of total unpaid losses and loss adjustment expenses at December 31, 2024 compared to 72% at December 31, 2023. In establishing liabilities for unpaid losses and loss adjustment expenses, the Company's actuaries estimate an ultimate loss ratio, by accident year or underwriting year, for each product line with input from underwriting and claims personnel. For product lines in which loss reserves are established on an underwriting year basis, the Company has developed a methodology to convert from underwriting year to accident year for financial reporting purposes. In estimating an ultimate loss ratio for a particular line of business, the actuaries may use one or more actuarial reserving methods and select from these a single point estimate. To varying degrees, these methods include detailed statistical analysis of past claim reporting, settlement activity, claim frequency and severity, policyholder loss experience, industry loss experience and changes in market and economic conditions, policy forms and exposures. Greater judgment may be required when new product lines are introduced or when there have been changes in claims handling practices, as the statistical data available may be insufficient. Greater judgment also may be required for product lines that experience a low frequency of high severity claims, particularly when the Company is reliant on third party case reserve estimates and claims handling practices. These estimates also reflect implicit and explicit assumptions regarding the potential effects of external factors, including economic and social inflation, judicial decisions, changes in law, general economic conditions and recent trends in these factors. Management believes the process of evaluating past experience, adjusted for the effects of current developments and anticipated trends, is an appropriate basis for predicting future events. Estimates for losses from widespread catastrophic events, such as hurricanes and earthquakes, as well as pandemics and wars, are based on claims received to date, analysis of exposures in the impacted areas, industry loss estimates and output from both industry, broker and proprietary models, as well as analysis of the Company's ceded reinsurance contracts. The level of reliance on these procedures varies depending on the timing of the event relative to the point at which the Company develops its estimates. The Company also considers loss experience on historical events that may have similar characteristics to the underlying event and current market conditions. In the period shortly after an event occurs, more weight is put on modeling and industry estimates, whereas with the passage of time, greater reliance is placed on incurred claims data, individual contract exposures and historical claim patterns. Due to the inherent uncertainty in estimating such losses, these estimates are subject to variability, which increases with the severity and complexity of the underlying event. As additional claims are reported and paid, and industry loss estimates are revised, the Company incorporates this new information into its analysis and adjusts its estimate of ultimate losses and loss adjustment expenses as appropriate. Loss reserves are established at management's best estimate, which is developed using the actuarially calculated point estimate as the starting point. The actuarial point estimate represents the actuaries' best estimate of the most likely amount that will ultimately be paid to settle the losses that have occurred at a particular point in time. Similarly, the point estimate for ceded losses is calculated based on the ultimate gross loss amount expected to be paid, as well as the frequency and severity of the underlying claims, which ultimately determines coverage under the applicable ceded reinsurance contracts. Therefore, ceded loss estimates are subject to many of the same judgments and assumptions as the gross loss estimates. Inherent in the Company's reserving practices is the desire to establish loss reserves that are more likely redundant than deficient, and therefore, will ultimately prove to be adequate. This approach to establishing loss reserves results in loss reserves that exceed the calculated actuarial point estimate. Management continually attempts to improve its loss estimation process by refining its ability to analyze loss development patterns, claim payments and other information, but uncertainty remains regarding the potential for adverse development of estimated ultimate liabilities. In some cases, actuarial analyses, which are generally based on statistical analysis, cannot fully incorporate all of the subjective factors that affect development of losses. In other cases, management's perspective of these more subjective factors may differ from the actuarial perspective. Subjective factors influencing the development of management's best estimate include: the credibility and timeliness of claims and loss information received from cedents and other third parties; and the impacts of economic and social inflation, judicial decisions, changes in law, changes in underwriting or claims handling practices, general economic conditions, the risk of moral hazard and other current and developing trends within the insurance and reinsurance markets, including the effects of competition. The Company's ultimate liability may be greater or less than current reserves. Changes in the Company's estimated ultimate liability for loss reserves generally occur as a result of the emergence of unanticipated loss activity, the completion of specific actuarial or claims studies or changes in internal or external factors that impact the assumptions used to derive the Company's estimates. The Company closely monitors new information on reported claims and uses statistical analyses prepared by its actuaries to evaluate the adequacy of recorded reserves. Management exercises judgment when assessing the relative credibility of loss development trends. Management currently believes the Company's gross and net reserves are adequate. However, there is no precise method for evaluating the impact of any significant factor on the adequacy of reserves, and actual results will differ from original estimates. c) Prior Accident Year Loss Development The following tables summarize, by segment, the product lines with the most significant changes in prior accident years loss reserves for the years ended December 31, 2024, 2023 and 2022, along with the corresponding accident years and the trends and factors that impacted management's best estimate of ultimate losses and loss adjustment expenses on underlying products in each of these product lines. The Company does not estimate losses at this level of aggregation as it offers a diverse portfolio of products and manages these products in more disaggregated groupings within each underwriting segment. As a result of the trends and factors described in the following tables, the Company's actuaries adjusted their estimates of the ultimate liability for unpaid losses and loss adjustment expenses. For those product lines with favorable development on prior accident years loss reserves, management has now given greater credibility to the favorable trends observed by the Company's actuaries and, upon incorporating these favorable trends into its best estimate, reduced prior years loss reserves accordingly. In 2023 and 2022, the unfavorable claims and loss trends experienced on the Company's U.S. general liability and professional liability product lines disrupted the development of the claims trend observed prior to 2022, reflecting broader market conditions, including the effects of economic and social inflation. In 2024, the Company's U.S. professional liability product lines continued to experience many of these same trends, while the U.S. general liability product lines began to stabilize, resulting in modest favorable development as management gave more credibility to the favorable trends observed by the Company's actuaries. Consistent with the Company's reserving philosophy, management is responding quickly to increase loss reserves following any indication of increased claims frequency or severity in excess of previous expectations, however in instances where trends have been more favorable than previously anticipated, management will wait to reduce loss reserves until those trends are observed over additional periods of time. Year Ended December 31, 2024 (dollars in millions) Loss Development Accident Years with Most Significant Development Trends and Factors Impacting Loss Estimates Insurance segment: Professional liability International $ (152.6) 2021 to 2023 Lower loss frequency and severity than previously anticipated, including on the cyber portfolio and middle market accounts U.S. 111.8 2017 to 2023 Unfavorable claims settlements and increased claim severity, primarily on the risk-managed directors and officers product line General liability (81.6) 2022 and 2023 More favorable loss experience within the U.S. business, as well as lower loss frequency and severity than previously anticipated on the international excess and umbrella product line Property (75.0) 2020 and 2023 Lower loss frequency and severity than previously anticipated across a number of subclasses in the U.S. and international portfolios Marine and energy (58.3) 2021 to 2023 More favorable loss experience than previously anticipated Programs (53.9) 2022 and 2023 Lower loss frequency and severity than previously anticipated on certain programs Credit and surety (51.4) 2021 to 2023 Lower loss frequency and severity than previously anticipated driven by the international trade credit product line Other products (90.0) Total Insurance (451.0) Reinsurance segment: Property (23.0) 2017 to 2020 Lower loss severity than previously anticipated and net favorable development on catastrophe events Workers' compensation (20.3) 2019, 2020 and 2023 Lower loss severity than previously anticipated and net favorable development on losses related to the COVID-19 pandemic Professional liability (17.1) 2021 to 2023 More favorable loss experience than previously anticipated Public entity 34.1 2017 to 2023 Increased frequency of large claims across the product line, which was discontinued in late 2024 Other products 18.0 Premium adjustments (4.0) Total Reinsurance (12.3) Other underwriting 8.0 Total decrease $ (455.3) Year Ended December 31, 2023 (dollars in millions) Loss Development Accident Years with Most Significant Development Trends and Factors Impacting Loss Estimates Insurance segment: General liability U.S. $ 274.0 2016 to 2021 Increased frequency of large claims and unfavorable loss cost trends, primarily on primary casualty contractors' liability and excess and umbrella product lines International (36.5) 2020 to 2022 Lower loss frequency and severity than previously anticipated Professional liability U.S. 56.8 Several Increased frequency of large claims and unfavorable loss cost trends, primarily on risk-managed errors and omissions product line International (102.2) 2020 Lower loss frequency and severity than previously anticipated Property (95.1) 2020 to 2022 Lower loss severity than previously anticipated and net favorable development on catastrophe events Marine and energy (76.5) 2021 and 2022 Lower loss severity than previously anticipated Personal lines (42.8) 2022 Lower loss frequency and severity than previously anticipated Workers' compensation (36.5) 2021 and 2022 Lower loss severity than previously anticipated Other products (45.9) Total Insurance (104.7) Reinsurance segment: General liability 95.5 2015 to 2021 Large reported claims and adverse loss development trends Public entity 53.7 2014 to 2019 Increased frequency of large claims on a segment of business that was discontinued in 2020 Premium adjustments 11.4 2021 and 2022 Recognition of additional exposures on prior accident years related to net favorable premium adjustments primarily on general liability, partially offset by reduced exposures recognized primarily on professional liability Property (21.6) 2017 to 2019 More favorable loss experience and lower loss severity than previously anticipated Workers' compensation (14.9) Several Lower loss frequency and severity than previously anticipated Other products (67.0) Total Reinsurance 57.1 Other underwriting 9.0 Total decrease $ (38.6) Year Ended December 31, 2022 (dollars in millions) Loss Development Accident Years with Most Significant Development Trends and Factors Impacting Loss Estimates Insurance segment: Professional liability 2018 and 2019 accident years $ 121.0 2018 and 2019 Unfavorable claims settlements and increased claim frequency and severity, primarily on directors and officers, errors and omissions and employment practices liability lines All other accident years (91.1) Several More favorable loss experience and lower loss severity than previously anticipated General liability 2016 to 2019 accident years 61.6 2016 to 2019 Unfavorable claims settlements and increased claim frequency and severity, primarily on contractors and excess and umbrella lines All other accident years (20.5) Several Lower loss frequency and severity than previously anticipated Workers' compensation (62.1) 2016 to 2021 Lower loss severity than previously anticipated Programs (48.3) 2020 and 2021 Lower than expected frequency of claims Property (48.1) 2020 and 2021 Lower loss severity than originally anticipated as well as favorable development on losses related to the COVID-19 pandemic Credit and surety (31.7) 2019 to 2021 Lower than expected frequency of claims Other products (23.7) Total Insurance (142.9) Reinsurance segment: Property (29.2) 2017 to 2019 Favorable development on catastrophe events Credit and surety (22.9) Several Favorable commutations on mortgage insurance contracts Premium adjustments 53.1 2020 and 2021 Recognition of additional exposures on prior accident years related to net favorable premium adjustments primarily on general liability, credit and surety and professional liability Other products (27.1) Total Reinsurance (26.1) Other 1.6 Total decrease $ (167.4) d) Historic Loss Development The following tables present undiscounted loss development information, by accident year, for the Company's Insurance and Reinsurance segments, including cumulative incurred and paid losses and allocated loss adjustment expenses, net of reinsurance, as well as the corresponding amount of IBNR reserves as of December 31, 2024. This level of disaggregation is consistent with how the Company analyzes loss reserves for both internal and external reporting purposes. The loss development information for the years ended December 31, 2015 through 2023 is presented as supplementary information. All amounts included in the following tables related to transactions denominated in a foreign currency have been translated into U.S. Dollars using the exchange rates in effect at December 31, 2024. The difference between the segment loss development implied by the tables for the year ended December 31, 2024 and actual losses and loss adjustment expenses recognized on prior accident years for the Insurance and Reinsurance segments for the year ended December 31, 2024 is primarily attributed to the fact that amounts presented in these tables exclude amounts attributed to the 2014 and prior accident years. Adverse development on 2014 and prior accident years for the year ended December 31, 2024 totaled $50.1 million for the Insurance segment, which was driven by general liability and programs product lines. The remaining difference between the segment loss development implied by the tables for the year ended December 31, 2024 and actual losses and loss adjustment expenses on prior accident years is attributed to the fact that amounts presented in these tables exclude unallocated loss adjustment expenses, as well as differences in the presentation of foreign currency movements, as previously described, none of which are material to the Insurance or Reinsurance segments. The Insurance segment table that follows also includes claim count information, by accident year. The Company defines a claim as a single claim incident, per policy, which may include multiple claimants and multiple coverages on a single policy. Claim counts include claims closed without a payment as well as claims where the Company is monitoring to determine if an exposure exists, even if a reserve has not been established. All of the business contained within the Company's Reinsurance segment represents treaty business that is assumed from other insurance or reinsurance companies, for which the Company does not have access to the underlying claim counts. Further, this business includes both quota share and excess of loss treaty reinsurance, through which only a portion of each reported claim results in losses to the Company. As such, the Company has excluded claim count information from the Reinsurance segment disclosures. Insurance Segment (dollars in millions) Ultimate Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance Total of Incurred-but-Not-Reported Liabilities, Net of Reinsurance Cumulative Number of Reported Claims Unaudited As of December 31, As of December 31, Accident Year 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 December 31, 2024 2015 $ 1,767.5 $ 1,693.8 $ 1,571.0 $ 1,517.0 $ 1,486.5 $ 1,454.7 $ 1,450.6 $ 1,440.9 $ 1,460.0 $ 1,457.1 $ 58.0 88,000 2016 1,856.3 1,852.8 1,753.6 1,700.3 1,674.7 1,667.4 1,678.4 1,732.9 1,718.1 77.2 100,000 2017 2,309.0 2,176.7 2,059.3 1,998.7 2,004.5 2,023.9 2,111.2 2,152.3 124.6 140,000 2018 2,429.0 2,320.8 2,199.2 2,058.8 2,151.2 2,331.6 2,417.1 177.8 193,000 2019 2,552.4 2,402.2 2,239.7 2,293.7 2,471.7 2,526.8 206.9 228,000 2020 3,185.1 2,972.1 2,914.2 2,858.5 2,771.6 434.3 183,000 2021 3,083.5 2,907.1 2,755.4 2,720.1 531.0 149,000 2022 3,746.8 3,365.5 3,342.6 1,098.3 159,000 2023 4,435.9 3,901.7 1,802.5 169,000 2024 4,532.5 3,271.7 149,000 Total $ 27,539.9 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance Unaudited As of December 31, As of December 31, Accident Year 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2015 $ 320.7 $ 660.0 $ 870.2 $ 1,032.9 $ 1,141.3 $ 1,208.4 $ 1,259.2 $ 1,291.7 $ 1,327.3 $ 1,344.7 2016 369.8 746.2 973.7 1,158.2 1,262.8 1,350.3 1,425.5 1,479.6 1,529.8 2017 434.9 982.7 1,274.3 1,462.0 1,619.2 1,739.8 1,839.6 1,909.5 2018 490.7 1,017.4 1,281.9 1,494.9 1,671.6 1,856.5 2,017.4 2019 524.1 991.1 1,262.9 1,576.4 1,910.9 2,104.4 2020 568.1 1,148.5 1,515.7 1,772.5 2,033.8 2021 473.4 985.8 1,357.5 1,751.1 2022 484.5 1,059.9 1,564.1 2023 596.9 1,396.6 2024 651.3 Total $ 16,302.7 All outstanding liabilities for unpaid losses and loss adjustment expenses before 2014, net of reinsurance 313.3 Total liabilities for unpaid losses and loss adjustment expenses, net of reinsurance $ 11,550.5 Variability in claim counts is primarily attributable to claim counts on pet health liability, a product which has a high claim frequency and low claim severity. There was an elevated number of claims on this product line in 2018, 2019 and 2020. The related net incurred losses and allocated loss adjustment expenses are not material to the Insurance segment. Reinsurance Segment Ultimate Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance Total of Incurred-but-Not-Reported Liabilities, Net of Reinsurance Unaudited As of December 31, (dollars in millions) As of December 31, Accident Year 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 December 31, 2024 2015 $ 523.0 $ 508.8 $ 524.6 $ 516.0 $ 504.8 $ 499.9 $ 487.8 $ 488.2 $ 500.0 $ 477.7 $ 56.6 2016 506.6 515.2 515.4 513.4 523.4 548.1 551.5 573.3 556.5 30.1 2017 894.4 927.6 933.2 934.9 907.3 919.7 931.0 931.3 44.2 2018 743.0 764.9 757.4 762.5 758.1 821.0 790.1 82.2 2019 654.4 668.4 683.1 691.0 719.0 730.4 129.1 2020 678.1 730.5 741.0 762.8 765.2 230.1 2021 731.9 733.6 754.7 753.9 303.8 2022 661.1 601.9 616.4 413.4 2023 658.3 665.3 506.7 2024 730.3 674.3 Total $ 7,017.1 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance Unaudited As of December 31, As of December 31, Accident Year 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2015 $ 63.3 $ 130.3 $ 201.0 $ 251.6 $ 298.6 $ 323.2 $ 342.8 $ 359.5 $ 375.6 $ 388.6 2016 78.6 166.7 236.4 292.7 344.4 377.9 418.0 451.6 475.7 2017 157.1 357.5 478.6 560.4 623.8 692.8 747.6 796.0 2018 86.9 235.1 334.9 404.4 474.4 543.6 613.9 2019 53.2 169.1 261.3 351.8 435.6 507.7 2020 93.2 202.9 308.7 381.8 463.0 2021 79.2 187.1 281.6 361.0 2022 24.1 66.6 138.4 2023 27.1 79.5 2024 23.9 Total $ 3,847.7 All outstanding liabilities for unpaid losses and loss adjustment expenses before 2014, net of reinsurance 273.3 Total liabilities for unpaid losses and loss adjustment expenses, net of reinsurance $ 3,442.7 The following table presents supplementary information about average historical claims duration as of December 31, 2024 based on the cumulative incurred and paid losses and allocated loss adjustment expenses presented above. Average Annual Percentage Payout of Incurred Losses by Age (in Years), Net of Reinsurance Unaudited 1 2 3 4 5 6 7 8 9 10 Insurance 18.7 % 20.9 % 13.1 % 10.8 % 8.5 % 6.1 % 4.8 % 2.9 % 2.7 % 1.2 % Reinsurance 9.6 % 14.4 % 12.9 % 10.1 % 9.5 % 7.4 % 6.5 % 4.9 % 3.8 % 2.7 % The following table reconciles the net incurred and paid loss development tables to the liability for losses and loss adjustment expenses on the consolidated balance sheet. (dollars in thousands) December 31, 2024 Net outstanding liabilities Insurance segment $ 11,550,516 Reinsurance segment 3,442,663 Other underwriting 62,903 Program services and ILS fronting 6,615 Markel CATCo Re (see note 17) 25,005 Liabilities for unpaid losses and loss adjustment expenses, net of reinsurance 15,087,702 Reinsurance recoverable on unpaid losses Insurance segment 4,129,856 Reinsurance segment 397,810 Other underwriting 84,079 Program services and ILS fronting 6,508,622 Total reinsurance recoverable on unpaid losses 11,120,367 Unallocated loss adjustment expenses 425,025 Total gross liability for unpaid losses and loss adjustment expenses $ 26,633,094 e) The Company has exposure to asbestos and environmental (A&E) claims primarily resulting from policies written by acquired insurance operations before their acquisition by the Company. The Company's exposure to A&E claims originated from umbrella, excess and commercial general liability insurance policies and assumed reinsurance contracts that were written on an occurrence basis from the 1970s to mid-1980s. Exposure also originated from claims-made policies that were designed to cover environmental risks provided that all other terms and conditions of the policy were met. A&E claims include property damage and clean-up costs related to pollution, as well as personal injury allegedly arising from exposure to hazardous materials. Development on A&E loss reserves is monitored separately from the Company's ongoing underwriting operations and is not included in a reportable segment. At December 31, 2024, A&E reserves were $122.1 million and $32.5 million on a gross and net basis, respectively. At December 31, 2023, A&E reserves were $132.5 million and $39.6 million on a gross and net basis, respectively. The Company's reserves for losses and loss adjustment expenses related to A&E exposures represent management's best estimate of ultimate settlement values based on statistical analysis of these reserves by the Company's actuaries. A&E exposures are subject to significant uncertainty due to potential loss severity and frequency resulting from the uncertain and unfavorable legal climate. A&E reserves could be subject to increases in the future, however, management believes the Company's gross and net A&E reserves at December 31, 2024 are adequate.

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2024
Reinsurance Disclosures [Abstract]
Reinsurance	12. Reinsurance In reinsurance and retrocession transactions, an insurance or reinsurance company transfers, or cedes, all or part of its exposure in return for a premium. The ceding of insurance does not legally discharge the Company from its primary liability for the full amount of the policies, and the Company will be required to pay the loss and bear collection risk if the reinsurer fails to meet its obligations under the reinsurance or retrocessional agreement. A credit risk exists with ceded reinsurance to the extent that any reinsurer is unable to meet the obligations assumed under the reinsurance or retrocessional contracts. Allowances are established for credit losses expected to be recognized over the life of the reinsurance recoverables. Within its underwriting operations, the Company uses reinsurance and retrocessional reinsurance to manage its net retention on individual risks and overall exposure to losses while providing it with the ability to offer policies with sufficient limits to meet policyholder needs. Within the Company's underwriting operations, at December 31, 2024, balances recoverable from the ten largest reinsurers, by group, represented 63% of the $5.0 billion reinsurance recoverables before considering reinsurance allowances and collateral. As of December 31, 2023, balances recoverable from the ten largest reinsurers, by group, represented 65% of the $4.0 billion reinsurance recoverables before considering reinsurance allowances and collateral. At December 31, 2024, the largest reinsurance balance was due from RenaissanceRe and represented 19% of reinsurance recoverables before considering reinsurance allowances and collateral. Within its program services and ILS fronting operations, the Company generally enters into quota share reinsurance agreements whereby the Company cedes to the capacity providers (reinsurers) substantially all of its gross liability under the policies issued by and on behalf of the Company by a general agent. However, there are certain programs that contain limits on the reinsurers' obligations to the Company that expose the Company to underwriting risk, including loss ratio caps, exclusions of the credit risk of producers and aggregate reinsurance limits that the Company believes are unlikely to be exceeded. The Company also remains exposed to the credit risk of the reinsurer, or the risk that one of its reinsurers becomes insolvent or otherwise unable or unwilling to pay policyholder claims. This credit risk is generally mitigated by either selecting well capitalized, highly rated authorized capacity providers or requiring that the capacity provider post substantial collateral to secure the reinsured risks, which, in some instances, exceeds the related reinsurance recoverable. Within the Company's program services business, at December 31, 2024, balances recoverable from the ten largest reinsurers, by group, represented 55% of the $6.0 billion reinsurance recoverables before considering reinsurance allowances and collateral. As of December 31, 2023, balances recoverable from the ten largest reinsurers, by group, represented 56% of the $4.9 billion reinsurance recoverables before considering reinsurance allowances and collateral. At December 31, 2024, the largest reinsurance balance was due from Lloyd's of London and represented 9% of reinsurance recoverables before considering reinsurance allowances and collateral. All of the Company's ILS fronting business is conducted by its Nephila ILS operations; therefore, substantially all of the reinsurance recoverables within these operations are attributable to entities managed by Nephila. See note 18. The following tables summarize the effect of reinsurance and retrocessional reinsurance on premiums written and earned. Year Ended December 31, 2024 (dollars in thousands) Direct Assumed Ceded Net Premiums Underwriting: Written $ 8,860,015 $ 1,691,858 $ (2,252,122) $ 8,299,751 Earned $ 8,801,477 $ 1,628,408 $ (1,993,895) $ 8,435,990 Fronting: Written 3,234,025 1,708,733 (4,946,334) (3,576) Earned 3,053,947 1,559,599 (4,617,124) (3,578) Consolidated: Written $ 12,094,040 $ 3,400,591 $ (7,198,456) $ 8,296,175 Earned $ 11,855,424 $ 3,188,007 $ (6,611,019) $ 8,432,412 Year Ended December 31, 2023 (dollars in thousands) Direct Assumed Ceded Net Premiums Underwriting: Written $ 8,657,266 $ 1,620,366 $ (1,878,844) $ 8,398,788 Earned $ 8,363,710 $ 1,616,630 $ (1,683,648) $ 8,296,692 Fronting: Written 2,649,217 1,075,388 (3,725,818) (1,213) Earned 2,636,179 937,400 (3,574,792) (1,213) Consolidated: Written $ 11,306,483 $ 2,695,754 $ (5,604,662) $ 8,397,575 Earned $ 10,999,889 $ 2,554,030 $ (5,258,440) $ 8,295,479 Year Ended December 31, 2022 (dollars in thousands) Direct Assumed Ceded Net Premiums Underwriting: Written $ 8,085,812 $ 1,761,726 $ (1,640,165) $ 8,207,373 Earned $ 7,379,766 $ 1,589,920 $ (1,378,191) $ 7,591,495 Fronting: Written 2,644,138 710,006 (3,358,127) (3,983) Earned 2,688,804 656,885 (3,349,392) (3,703) Consolidated: Written $ 10,729,950 $ 2,471,732 $ (4,998,292) $ 8,203,390 Earned $ 10,068,570 $ 2,246,805 $ (4,727,583) $ 7,587,792 Substantially all of the premiums written and earned in the Company's fronting operations for the years ended December 31, 2024, 2023 and 2022 were ceded. The percentage of consolidated ceded earned premiums to gross earned premiums was 44%, 39% and 38% for the years ended December 31, 2024, 2023 and 2022, respectively. The percentage of consolidated assumed earned premiums to net earned premiums was 38%, 31% and 30% for the years ended December 31, 2024, 2023 and 2022, respectively. Substantially all of the incurred losses and loss adjustment expenses in the Company's fronting operations were ceded. These losses totaled $3.5 billion, $2.5 billion, and $3.0 billion for the years ended December 31, 2024, 2023, and 2022 respectively. The following table summarizes the effect of reinsurance and retrocessional reinsurance on losses and loss adjustment expenses in the Company's underwriting operations. Years ended December 31, (dollars in thousands) 2024 2023 2022 Gross losses and loss adjustment expenses $ 6,970,871 $ 6,817,630 $ 5,281,424 Ceded losses and loss adjustment expenses (1,917,318) (1,496,265) (834,648) Net losses and loss adjustment expenses $ 5,053,553 $ 5,321,365 $ 4,446,776

Life And Annuity Benefits

Life And Annuity Benefits	12 Months Ended
	Dec. 31, 2024
Life And Annuity Benefits	13. 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. December 31, (dollars in thousands) 2024 2023 Liability for future policyholder benefits $ 491,370 $ 557,763 Deferred profit liability 51,482 52,287 Other 40,421 39,004 Total $ 583,273 $ 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. There were no changes to the cash flow assumptions used to measure the Company's life and annuity benefit reserves in 2024, 2023 and 2022. The following table presents a rollforward of the present value of the liability for future policyholder benefits. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Liability for future policyholder benefits, beginning of year $ 557,763 $ 554,366 $ 821,632 Liability for future policyholder benefits at original discount rate, beginning of year 642,877 667,761 745,313 Effect of changes in cash flow assumptions — — — Effect of actual variances from expected experience (4,745) (5,890) (3,859) Adjusted liability for future policyholder benefits, beginning of year 638,132 661,871 741,454 Interest accretion 13,996 14,889 15,625 Benefit payments (49,200) (52,588) (53,232) Effect of foreign currency rate changes (26,126) 18,705 (36,086) Liability for future policyholder benefits at original discount rate, end of year 576,802 642,877 667,761 Cumulative effect of changes in discount rate assumptions (85,432) (85,114) (113,395) Liability for future policyholder benefits, end of year $ 491,370 $ 557,763 $ 554,366 Liability for future policyholder benefits, undiscounted, end of year $ 737,575 $ 824,642 $ 861,264 The following table summarizes additional details for the Company's liability for future policyholder benefits. December 31, 2024 2023 Weighted-average interest rate: Interest accretion rate 2.3 % 2.3 % Current discount rate 4.0 % 3.8 % Weighted-average liability duration 8.3 years 8.6 years

Senior Long-Term Debt And Other

Senior Long-Term Debt And Other Debt	12 Months Ended
	Dec. 31, 2024
Debt Disclosure [Abstract]
Senior Long-Term Debt And Other Debt	14. Senior Long-Term Debt and Other Debt The following table summarizes the Company's senior long-term debt and other debt. December 31, (dollars in thousands) 2024 2023 3.50% unsecured senior notes, due November 1, 2027, interest payable semi-annually, net of unamortized discount of $592 in 2024 and $876 in 2023 $ 299,236 $ 298,869 3.35% unsecured senior notes, due September 17, 2029, interest payable semi-annually, net of unamortized discount of $1,174 in 2024 and $1,421 in 2023 298,590 298,294 7.35% unsecured senior notes, due August 15, 2034, interest payable semi-annually, net of unamortized discount of $663 in 2024 and $731 in 2023 129,148 129,076 5.0% unsecured senior notes, due March 30, 2043, interest payable semi-annually, net of unamortized discount of $4,087 in 2024 and $4,311 in 2023 245,687 245,451 5.0% unsecured senior notes, due April 5, 2046, interest payable semi-annually, net of unamortized discount of $5,202 in 2024 and $5,445 in 2023 494,135 493,860 4.30% unsecured senior notes, due November 1, 2047, interest payable semi-annually, net of unamortized discount of $3,364 in 2024 and $3,516 in 2023 296,049 295,870 5.0% unsecured senior notes, due May 20, 2049, interest payable semi-annually, net of unamortized discount of $6,378 in 2024 and $6,639 in 2023 592,538 592,233 4.15% unsecured senior notes, due September 17, 2050, interest payable semi-annually, net of unamortized discount of $4,563 in 2024 and $4,740 in 2023 494,749 494,546 3.45% unsecured senior notes, due May 7, 2052, interest payable semi-annually, net of unamortized discount of $7,626 in 2024 and $7,904 in 2023 591,316 591,000 6.00% unsecured senior notes, due May 16, 2054, interest payable semi-annually, net of unamortized discount of $7,240 in 2024 and $0 in 2023 591,511 — Other debt, with a weighted average interest rate of 5.4% in 2024 and 5.0% in 2023 297,382 340,597 Senior long-term debt and other debt $ 4,330,341 $ 3,779,796 In May 2024, the Company issued $600 million of 6.0% unsecured senior notes due May 2054. Net proceeds to the Company were $592.6 million, before expenses. The Company intends to use these proceeds for general corporate purposes, which may include the redemption, in whole or in part, of its outstanding Series A preferred shares. See note 19. In March 2023, the Company retired its $250 million 3.625% unsecured senior notes due March 30, 2023. The Company's 7.35% unsecured senior notes due August 15, 2034 are not redeemable. The Company's other unsecured senior notes are redeemable by the Company at any time, subject to payment of a make-whole premium to the noteholders. None of the Company's senior long-term debt is subject to any sinking fund requirements. The Company's other debt is comprised of debt associated with its Markel Ventures subsidiaries. As of December 31, 2024 and 2023, debt at the Company's Markel Ventures subsidiaries was $297.4 million and $339.0 million, respectively, which includes amounts outstanding on their respective credit facilities. The Markel Ventures debt is non-recourse to the holding company and generally is secured by the assets of those subsidiaries. Various of the Company's Markel Ventures subsidiaries maintain revolving credit facilities or lines of credit, which provide up to $692 million of aggregate capacity for working capital and other general operational purposes. A portion of the capacity on certain of these credit facilities may be used as security for letters of credit and other obligations. At December 31, 2024 and 2023, $150.0 million and $169.5 million, respectively, of borrowings were outstanding under these credit facilities. As of December 31, 2024, all of the Company's subsidiaries were in compliance with all covenants contained in their respective credit facilities. The estimated fair value of the Company's senior long-term debt and other debt was $3.8 billion and $3.4 billion at December 31, 2024 and 2023, respectively. The following table summarizes the future principal payments on senior long-term debt and other debt as of December 31, 2024. (dollars in thousands) Senior long-term debt Other debt Total Years Ending December 31, 2025 $ — $ 41,843 $ 41,843 2026 — 41,902 41,902 2027 300,000 158,376 458,376 2028 — 16,724 16,724 2029 300,000 15,182 315,182 2030 and thereafter 3,479,846 25,905 3,505,751 Total principal payments 4,079,846 299,932 4,379,778 Net unamortized discount (40,889) — (40,889) Net unamortized debt issuance costs (5,998) (2,550) (8,548) Total $ 4,032,959 $ 297,382 $ 4,330,341 Markel Group and certain insurance subsidiaries maintain a corporate revolving credit facility, which provides up to $300 million of capacity for future acquisitions, investments and stock repurchases, and for other working capital and general corporate purposes. At the Company's discretion, up to $200 million of the total capacity may be used for letters of credit. The Company may increase the capacity of the facility by up to $200 million subject to obtaining commitments for the increase and certain other terms and conditions. The Company pays interest on balances outstanding under the facility and a utilization fee for letters of credit issued under the facility. The Company also pays a commitment fee (0.20% at December 31, 2024) on the unused portion of the facility based on the Company's leverage ratio as calculated under the credit agreement. The credit agreement includes financial covenants that require that the Company not exceed a maximum debt to capitalization (leverage) ratio and maintain a minimum amount of consolidated net worth, as well as other customary covenants and events of default. Markel Group guarantees the obligations under the facility of the insurance subsidiaries that are also parties to the credit agreement. This facility expires in June 2028. The credit agreement for this revolving credit facility amended and restated the credit agreement for the Company's previous $300 million revolving credit facility. At December 31, 2024 and 2023, the Company had no borrowings outstanding under this revolving credit facility. As of December 31, 2024, the Company was in compliance with all covenants contained in its corporate revolving credit facility. To the extent that Markel Group or any of its subsidiaries are not in compliance with the covenants under their respective credit facilities, access to such credit facilities could be restricted. The Company paid $197.4 million, $187.8 million and $197.3 million in interest on its senior long-term debt and other debt during the years ended December 31, 2024, 2023 and 2022, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	15. Income Taxes Income (loss) before income taxes includes the following components, based on country of domicile. Years Ended December 31, (dollars in thousands) 2024 2023 2022 U.S. operations $ 2,428,694 $ 1,711,849 $ (109,311) Foreign operations 1,209,006 941,857 (42,255) Income (loss) before income taxes $ 3,637,700 $ 2,653,706 $ (151,566) Income tax expense (benefit) includes the following components, based on the taxing authority to which taxes are paid. The Company's most significant U.K. and Bermuda subsidiaries have elected to be taxed as domestic corporations for U.S. tax purposes. U.S. income taxes have not been recognized on any undistributed earnings of the Company's foreign subsidiaries that are considered indefinitely reinvested, the amount of which is not material to the consolidated financial statements. U.S. income tax includes applicable state income tax expense. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Current: U.S. income tax $ 271,801 $ 249,149 $ 222,074 Foreign income tax 123,933 69,669 12,042 Total current tax expense 395,734 318,818 234,116 Deferred: U.S. income tax 399,169 250,041 (301,423) Foreign income tax (4,609) (16,243) 19,098 Total deferred tax expense (benefit) 394,560 233,798 (282,325) Income tax expense (benefit) $ 790,294 $ 552,616 $ (48,209) The Company made net income tax payments of $382.5 million, $280.7 million and $251.5 million in 2024, 2023 and 2022, respectively. Income taxes payable were $40.3 million and $29.4 million at December 31, 2024 and 2023, respectively, and were included in other liabilities on the consolidated balance sheets. Income taxes receivable were $13.3 million and $0.3 million at December 31, 2024 and 2023, respectively, and were included in other assets on the consolidated balance sheets. The following table presents a reconciliation of the Company's income taxes using the U.S. corporate income tax rate to the Company's income tax expense (benefit). Years Ended December 31, (dollars in thousands) 2024 2023 2022 U.S. corporate tax rate $ 763,917 21.0 % $ 557,278 21.0 % $ (31,829) 21.0 % Increase (decrease) resulting from: State income taxes, net of U.S. federal income tax benefit 39,770 1.1 27,007 1.0 3,369 (2.2) Tax-exempt investment income (14,830) (0.4) (15,328) (0.6) (16,063) 10.6 Foreign operations 12,985 0.3 10,854 0.4 5,335 (3.5) Impairment of goodwill — — — — 16,800 (11.1) Markel CATCo Re income not subject to tax (12,201) (0.3) (15,013) (0.6) (18,871) 12.5 Other 653 0.0 (12,182) (0.4) (6,950) 4.5 Income tax expense (benefit) $ 790,294 21.7 % $ 552,616 20.8 % $ (48,209) 31.8 % The following table presents the components of domestic and foreign deferred tax assets and liabilities. December 31, (dollars in thousands) 2024 2023 Assets: Unpaid losses and loss adjustment expenses $ 233,583 $ 216,863 Lease liabilities 172,131 161,350 Unearned premiums 164,485 168,172 Accrued incentive compensation 51,943 52,853 Tax credit carryforwards 45,481 25,396 Net operating loss carryforwards 37,168 43,439 Life and annuity benefits 29,143 39,729 Other differences between financial reporting and tax bases 106,667 93,693 Total gross deferred tax assets 840,601 801,495 Less valuation allowance (33,292) (13,916) Total gross deferred tax assets, net of allowance 807,309 787,579 Liabilities: Investments 1,566,540 1,196,717 Deferred policy acquisition costs 173,742 176,382 Goodwill and other intangible assets 170,941 175,767 Right-of-use lease assets 162,628 152,939 Property, plant and equipment 160,615 152,149 Other differences between financial reporting and tax bases 113,873 104,024 Total gross deferred tax liabilities 2,348,339 1,957,978 Net deferred tax liability $ 1,541,030 $ 1,170,399 Deferred tax assets and liabilities are recorded on the consolidated balance sheets on a net basis by taxing jurisdiction. As of December 31, 2024 and 2023, the Company's consolidated balance sheets included net deferred tax liabilities of $1.6 billion and $1.2 billion, respectively, in other liabilities and net deferred tax assets of $40.0 million and $23.5 million, respectively, in other assets. At December 31, 2024, the Company had tax credit carryforwards of $45.5 million, substantially all of which related to foreign tax credits to be used against U.S. income tax. The Company expects to utilize all tax credit carryforwards before expiration. The earliest any of these credits will expire is 2034. At December 31, 2024, the Company had deferred tax assets of $28.9 million for U.S. state net operating loss carryforwards and $7.7 million for foreign net operating loss carryforwards, which are available to offset future taxable income in certain U.S. state and foreign jurisdictions, respectively. The Company's ability to benefit from the majority of these net operating loss carryforwards is not subject to expiration. As described below, the deferred tax assets related to losses at certain of the Company's subsidiaries and branches are offset by valuation allowances. At December 31, 2024, the Company had total gross deferred tax assets of $840.6 million. The Company has a valuation allowance of $33.3 million to offset gross deferred tax assets at certain of the Company's international subsidiaries and branches. The Company believes that it is more likely than not that it will realize the remaining $807.3 million of gross deferred tax assets through generating taxable income or the reversal of existing temporary differences attributable to the gross deferred tax liabilities. Additionally, the Company's net deferred tax liability for investments includes deferred tax assets attributed to its unrealized losses on fixed maturity securities. The Company has the ability and intent to execute a tax planning strategy such that it is more likely than not that all of these deferred tax assets will be realized. At December 31, 2024, the Company did not have any material unrecognized tax benefits. The Company does not anticipate any changes in unrecognized tax benefits during 2025 that would have a material impact on the Company's income tax provision. The Company is subject to income tax in the U.S. and in foreign jurisdictions. The Internal Revenue Service is currently examining the Company's 2017 U.S. federal income tax return. The Company believes its income tax liabilities are adequate as of December 31, 2024, however, these liabilities could be adjusted as a result of this examination. With few exceptions, including the 2017 U.S. federal income tax return, the Company is no longer subject to income tax examination by tax authorities for years ended before January 1, 2021.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2024
Postemployment Benefits [Abstract]
Employee Benefit Plans	16. Employee Benefit Plans a) The Company maintains a defined contribution plan for employees of its U.S. insurance operations in accordance with Section 401(k) of the U.S. Internal Revenue Code of 1986. The Company also provides various defined contribution plans for employees of its international insurance operations, which are in line with local market terms and conditions of employment. Employees of the Company's Markel Ventures subsidiaries are provided post-retirement benefits under separate defined contribution plans established by the individual companies. Expenses relating to the Company's defined contribution plans we re $72.4 million , $65.4 million and $57.9 million in 2024, 2023 and 2022, respectively. b) The Terra Nova Pension Plan is a defined benefit plan that covers certain employees in the Company's international insurance operations who meet the eligibility conditions set out in the plan. The plan has been closed to new participants since 2001, and employees have not accrued benefits for future service in the plan since 2012. The projected benefit obligations of the Terra Nova Pension Plan as of December 31, 2024 and 2023 were $105.4 million and $117.3 million, respectively, and the related fair value of plan assets was $168.8 million and $184.6 million, respectively. The corresponding net asset for pension benefits, also referred to as the funded status of the plan, at December 31, 2024 and 2023 was included in other assets on the Company's consolidated balance sheets.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	17. 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. (MCRe), 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 MCRe 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 MCRe. The underwriting results of MCRe are attributed to investors through its nonvoting preference shares. Both MCRe and the Markel CATCo Funds were placed into run-off in July 2019. In 2022, the Company completed a buy-out transaction with MCRe 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 MCRe. 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. In order to complete the transaction, the Company also made $101.9 million in additional payments, net of insurance proceeds, to or for the benefit of investors, which were recognized as an expense to the Company and included in services and other expenses in 2022. The Company has received a return of $24.9 million of the capital it provided, and the related preference shares were redeemed. In November 2024, following the commutation of certain reinsurance contracts, $117.2 million of collateral held by MCRe was released, which allowed for the redemption of the corresponding preferred shares held by Markel CATCo Funds. As of December 31, 2024 and 2023, the Company's investment in the remaining preference shares of MCRe totaled $20.1 million, which comprised 52% and 23%, respectively, of the equity of MCRe. Through that investment, the Company has exposure to adverse loss development on reinsurance contracts previously written by MCRe for loss events that occurred from 2014 to 2020. If loss reserves held by MCRe 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 MCRe, less operating expenses, will be distributed to the Markel CATCo Funds, and ultimately to investors in the Markel CATCo Funds. MCRe 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 MCRe as its primary beneficiary. Results attributed to the run-off of MCRe 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 years ended December 31, 2024, 2023, and 2022, there was $58.1 million, $71.5 million, and $89.9 million respectively, of favorable loss reserve development on the run-off of reinsurance contracts written by MCRe, all of which was included in services and other expenses and attributable to noncontrolling interests. During the years ended December 31, 2024, 2023, and 2022, $117.2 million, $62.6 million, and $22.3 million respectively, of preference shares of MCRe held by noncontrolling interests were redeemed. The Company's consolidated balance sheets include the following amounts attributable to MCRe. December 31, ( dollars in thousands ) 2024 2023 Assets Cash and cash equivalents $ 34,497 $ 91,301 Restricted cash and cash equivalents 28,701 173,800 Other assets and receivables due from cedents 329 19,292 Total Assets $ 63,527 $ 284,393 Liabilities and Equity Unpaid losses and loss adjustment expenses $ 25,005 $ 184,967 Other liabilities 66 1,842 Total Liabilities 25,071 186,809 Shareholders' equity 21,139 21,139 Noncontrolling interests 17,317 76,445 Total Equity 38,456 97,584 Total Liabilities and Equity $ 63,527 $ 284,393 In connection with the buy-out transaction, the Company also entered into a tail risk cover with MCRe 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 MCRe for loss exposures in excess of limits that the Company believes are unlikely to be exceeded.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2024
Related Party Transactions [Abstract]
Related Party Transactions [Text Block]	18. Related Party Transactions The Company engages in certain related party transactions in the normal course of business at arm's length. Fund Management 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 licensed reinsurers and as the managing agent to Lloyd's Syndicate 2357 and Lloyd's Syndicate 2358 (collectively, the Nephila Reinsurers). Neither the Nephila Funds nor the Nephila Reinsurers are consolidated by the Company. Nephila receives management fees for its investment and insurance management services based on either the net asset value of the accounts managed or gross premium volume for the underlying risks to which the investors subscribed. Nephila also may earn incentive fees from certain funds based on annual performance. For the years ended December 31, 2024, 2023 and 2022, total fund management revenues attributed to unconsolidated entities managed by Nephila were $94.6 million, $97.6 million and $74.3 million, respectively. Program Services and ILS Fronting Through the Company's program services and ILS fronting operations, the Company has programs with the Nephila Reinsurers through which the Company writes insurance policies that are fully ceded to the Nephila Reinsurers in exchange for fronting fees. Through these programs, Nephila utilizes certain of the Company's licensed insurance companies to write a portion of its portfolio of U.S. catastrophe-exposed property and specialty risks. A portion of this business is placed by Velocity, a managing general agent in which the Company has a minority interest. Gross premiums written through the Company's program services and ILS operations that were ceded to the Nephila Reinsurers were $1.3 billion, $1.1 billion and $1.0 billion for the years ended December 31, 2024, 2023 and 2022, respectively, for which the Company earned fronting fees totaling $39.4 million, $34.7 million and $37.0 million, respectively. As of December 31, 2024 and 2023, reinsurance recoverables on the consolidated balance sheets included $968.9 million and $794.3 million, respectively, due from Nephila Reinsurers. Under its programs with 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. Beginning in 2024, in order for the Nephila Reinsurers to obtain reinsurance protection for a portion of their exposures, the Company also fronted ceded reinsurance contracts, primarily in the form of industry loss warranties, for the Nephila Reinsurers. Through this arrangement, the underlying risk of the Nephila Reinsurers was retroceded back to the Company and then fully ceded to third-party reinsurers. In 2024, the Company's gross written premiums from the Nephila Reinsurers under this ILS fronting program were $168.0 million, all of which were ceded to third parties. 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. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Gross written premiums attributable to Hagerty $ 922,657 $ 805,673 $ 689,670 Premiums ceded to Hagerty Re $ 708,147 $ 616,491 $ 456,637 As of December 31, 2024 and 2023, reinsurance recoverables on the consolidated balance sheets included $308.8 million and $214.8 million, respectively, due from Hagerty Re.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2024
Stockholders' Equity Note [Abstract]
Shareholders' Equity	19. 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. Years Ended December 31, (in ones) 2024 2023 Issued and outstanding common shares, beginning of year 13,131,672 13,422,692 Issuance of common shares 28,479 30,740 Repurchase of common shares (370,034) (321,760) Issued and outstanding common shares, end of year 12,790,117 13,131,672 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 December 31, 2024 and 2023. The Company has the option to redeem the preferred shares: • in whole but not in part, at any time, within 90 days after the occurrence of a "rating agency event," at $1,020 per preferred share, plus accrued and unpaid dividends, • in whole but not in part, at any time, within 90 days after the occurrence of a "regulatory capital event" at $1,000 per preferred share, plus accrued and unpaid dividends, or • in whole or in part, on June 1, 2025, or every fifth anniversary of that date, at $1,000 per preferred share, plus accrued and unpaid dividends. A "rating agency event" means that any nationally recognized statistical rating organization that publishes a rating for the Company amends, clarifies or changes the criteria it uses to assign equity credit to securities like the preferred shares, which results in shortening the length of time that the preferred shares are assigned a particular level of equity credit or in the lowering of the equity credit assigned to the preferred shares. A "regulatory capital event" means that the Company becomes subject to capital adequacy supervision by a capital regulator and determines that, under such capital adequacy guidelines, the liquidation preference amount of the preferred shares would not qualify as capital. The preferred shares rank senior to the Company's common stock with respect to the payment of dividends and liquidation rights. Holders of the preferred shares are entitled to receive non-cumulative cash dividends, when, as and if declared by the Board of Directors, from the original issue date, semi-annually in arrears on the first day of June and December of each year. The Company accrues dividends when they are declared by the Board of Directors. To the extent declared, these dividends will accrue, on the liquidation preference of $1,000 per share, at a fixed annual rate of 6.00% from the original issue date to June 1, 2025. After June 1, 2025, the dividend rate will reset every five For both years ended December 31, 2024 and 2023, the Company declared and paid dividends on preferred shares of $36.0 million, or $60.00 per share. c) The following table presents net income (loss) per common share and diluted net income (loss) per common share. Years Ended December 31, (in thousands, except per share amounts) 2024 2023 2022 Net income (loss) to common shareholders $ 2,711,022 $ 1,960,060 $ (252,277) Adjustment of redeemable noncontrolling interests (111,700) 6,212 (69,896) Adjusted net income (loss) to common shareholders $ 2,599,322 $ 1,966,272 $ (322,173) Weighted average basic common shares outstanding 13,017 13,347 13,580 Weighted average dilutive potential common shares from restricted stock units and restricted stock (1) (2) 24 31 — Weighted average diluted common shares outstanding 13,041 13,378 13,580 Basic net income (loss) per common share $ 199.69 $ 147.32 $ (23.72) Diluted net income (loss) per common share (1) (2) $ 199.32 $ 146.98 $ (23.72) (1) The Company has issued grants and awards of restricted stock units to employees as performance, retention or hiring incentives, as well as awards of restricted stock to non-employee directors, under its equity incentive compensation plan. At December 31, 2024, there were 284,049 shares available for future awards under the Company's equity incentive compensation plan. (2) The impact of 33 thousand shares from restricted stock units and restricted stock was excluded from the computation of diluted net loss per common share for the year ended December 31, 2022 because the effect would have been anti-dilutive.

Other Comprehensive Income

Other Comprehensive Income	12 Months Ended
	Dec. 31, 2024
Other Comprehensive Income (Loss), Tax [Abstract]
Other Comprehensive Income	20. Other Comprehensive Income Other comprehensive income includes changes in net unrealized gains (losses) on available-for-sale investments, which is comprised of net holding gains (losses) arising during the period, changes in unrealized other-than-temporary impairment losses, if any, and reclassification adjustments for net realized gains included in net income. Other comprehensive income also includes changes in the discount rate for life and annuity benefits, changes in foreign currency translation adjustments and changes in net actuarial pension loss. The following table presents the change in accumulated other comprehensive income (loss) by component, net of noncontrolling interests. (dollars in thousands) Net unrealized gains (losses) on available-for-sale investments Life and annuity discount rate assumption Foreign currency Net actuarial pension loss Accumulated other comprehensive income (loss) December 31, 2021 $ 388,554 $ (60,291) $ (56,631) $ (49,624) $ 222,008 Total other comprehensive income (loss) before income taxes (1,463,876) 189,714 (9,677) 31,222 (1,252,617) Income tax (expense) benefit 309,046 (39,840) 401 (6,492) 263,115 Total other comprehensive income (loss) (1,154,830) 149,874 (9,276) 24,730 (989,502) December 31, 2022 $ (766,276) $ 89,583 $ (65,907) $ (24,894) $ (767,494) Total other comprehensive income (loss) before income taxes 390,558 (28,281) 4,650 94 367,021 Income tax (expense) benefit (83,655) 5,938 — (20) (77,737) Total other comprehensive income (loss) 306,903 (22,343) 4,650 74 289,284 December 31, 2023 $ (459,373) $ 67,240 $ (61,257) $ (24,820) $ (478,210) Total other comprehensive income (loss) before income taxes (165,423) 319 (3,883) (6,600) (175,587) Income tax (expense) benefit 35,128 (67) — 1,654 36,715 Total other comprehensive income (loss) (130,295) 252 (3,883) (4,946) (138,872) December 31, 2024 $ (589,668) $ 67,492 $ (65,140) $ (29,766) $ (617,082)

Commitments And Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	21. Commitments and 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.

Statutory Financial Information

Statutory Financial Information	12 Months Ended
	Dec. 31, 2024
Statutory Financial Information [Abstract]
Statutory Financial Information	22. Statutory Financial Information a) The following table summarizes statutory capital and surplus for the Company's insurance subsidiaries. December 31, (dollars in thousands) 2024 2023 United States $ 6,764,770 $ 5,958,801 United Kingdom $ 1,001,574 $ 977,604 Bermuda $ 2,414,364 $ 2,353,058 Germany $ 171,581 $ 166,403 As of December 31, 2024, the Company's actual statutory capital and surplus significantly exceeded the regulatory requirements. As a result, the amount of statutory capital and surplus necessary to satisfy regulatory requirements is not significant in relation to actual statutory capital and surplus. The following table summarizes statutory net income (loss) for the Company's insurance subsidiaries. Years Ended December 31, (dollars in thousands) 2024 2023 2022 United States $ 500,860 $ 196,952 $ 689,341 United Kingdom $ 62,084 $ 116,436 $ 35,719 Bermuda $ 614,056 $ 484,417 $ (144,239) Germany $ 10,075 $ 5,543 $ (2,471) Amounts presented for the Company's U.S. insurance subsidiaries have been calculated in accordance with prescribed statutory accounting rules. For the Company's international insurance subsidiaries, the regulations that govern the calculation of statutory capital and surplus do not provide requirements for the calculation of net income. Rather, such amounts are reported in accordance with a basis of accounting permitted by their respective regulator. Amounts presented for the Company's U.K., Bermuda and German insurance subsidiaries have been calculated in accordance with U.K. GAAP, U.S. GAAP and German GAAP, respectively. United States The laws of the domicile states of the Company's U.S. insurance subsidiaries govern the amount of dividends that may be paid to the holding company. Generally, statutes in the domicile states of the Company's U.S. insurance subsidiaries require prior approval for payment of extraordinary, as opposed to ordinary, dividends. As of December 31, 2024, the Company's U.S. insurance subsidiaries could pay up to $672.9 million to the holding company during the following 12 months under the ordinary dividend regulations. In converting from U.S. statutory accounting principles to U.S. GAAP, typical adjustments include deferral of policy acquisition costs, differences in the calculation of deferred income taxes and the inclusion of net unrealized gains or losses relating to fixed maturity securities in shareholders' equity. The Company does not use any permitted statutory accounting practices that are different from prescribed statutory accounting practices which impact statutory capital and surplus. United Kingdom The Company's U.K. insurance subsidiary, Markel International Insurance Company Limited (MIICL), and its Lloyd's managing agent, Markel Syndicate Management Limited (MSM), are authorized by the Prudential Regulation Authority (PRA) and regulated by both the PRA and the Financial Conduct Authority (FCA). The PRA oversees compliance with established periodic auditing and reporting requirements, minimum solvency margins and individual capital assessment requirements under the Solvency II Directive (Solvency II) and imposes dividend restrictions, while both the PRA and the FCA oversee compliance with risk assessment reviews and various other requirements. MIICL is required to give advance notice to the PRA for any transaction or proposed transaction with a connected or related person. MSM is required to satisfy the solvency requirements of Lloyd's. In addition, the Company's U.K. subsidiaries must comply with the United Kingdom Companies Act of 2006, which provides that dividends may only be paid out of profits available for that purpose. Earnings of the Company's U.K. insurance subsidiaries are available for distribution to the holding company to the extent not otherwise restricted. Bermuda The Company's Bermuda insurance subsidiary, Markel Bermuda Limited (MBL), is subject to enhanced capital requirements in addition to minimum solvency and liquidity requirements. The enhanced capital requirement is determined by reference to a risk-based capital model that determines a control threshold for statutory capital and surplus by taking into account the risk characteristics of different aspects of the insurer's business. At December 31, 2024, MBL satisfied both the enhanced capital requirements and the minimum solvency and liquidity requirements. Under the Bermuda Insurance Act, MBL is prohibited from paying or declaring dividends during a fiscal year if it is in breach of its enhanced capital requirement, solvency margin or minimum liquidity ratio or if the declaration or payment of the dividend would cause a breach of those requirements. If an insurer fails to meet its solvency margin or minimum liquidity ratio on the last day of any financial year, it is prohibited from declaring or paying any dividends during the next financial year without the approval of the Bermuda Monetary Authority (BMA). Further, MBL is prohibited from declaring or paying, in any financial year, dividends of more than 25% of its total statutory capital and surplus as set forth in its previous year's statutory balance sheet unless at least seven days before payment of those dividends it files with the BMA an affidavit stating that it will continue to meet its solvency margin and minimum liquidity ratio. MBL must obtain the BMA's prior approval for a reduction by 15% or more of the total statutory capital as set forth in its previous year's financial statements. In addition, as a long-term insurer, MBL may not declare or pay a dividend to any person other than a policyholder unless the value of the assets in its long-term business fund, as certified by MBL's approved actuary, exceeds the liabilities of its long-term business. The amount of the dividend cannot exceed the aggregate of that excess and any other funds legally available for the payment of the dividend. As of December 31, 2024, MBL could pay up to $603.6 million to the holding company during the following 12 months without making any additional filings with the BMA. Germany The Company's German insurance subsidiary, Markel Insurance SE, is regulated by the Federal Financial Conduct Authority in Germany and is also subject to capital and solvency requirements under Solvency II. b) Lloyd's sets the corporate members' required capital annually based on each syndicates' business plans, rating environment, reserving environment and input arising from Lloyd's discussions with, among others, regulatory and rating agencies. Such required capital is referred to as Funds at Lloyd's (FAL) and comprises cash and investments. The amount of cash and investments held as FAL as of December 31, 2024 was $913.7 million. Of this amount, $272.4 million was provided by the holding company and is not available for general use by the Company. The remaining amount, provided by the Company's insurance subsidiaries, is not available for distribution to the holding company. The Company's corporate member may also be required to maintain funds under the control of Lloyd's in excess of its capital requirements and such funds also may not be available for distribution to the holding company.

Markel Group (Parent Company On

Markel Group (Parent Company Only) Financial Information	12 Months Ended
	Dec. 31, 2024
Condensed Financial Information Disclosure [Abstract]
Markel Group (Parent Company Only) Financial Information	23. Markel Group Inc. (Parent Company Only) Financial Information The following parent company only condensed financial information reflects the financial position, results of operations and cash flows of Markel Group Inc. CONDENSED BALANCE SHEETS December 31, 2024 2023 (dollars in thousands) ASSETS Investments, at estimated fair value: Fixed maturity securities, available-for-sale (amortized cost of $130,983 in 2024 and $139,766 in 2023) $ 123,053 $ 131,544 Equity securities (cost of $1,084,814 in 2024 and $1,089,332 in 2023) 2,071,110 1,731,839 Short-term investments, available-for-sale (estimated fair value approximates cost) 1,410,830 1,032,118 Total Investments 3,604,993 2,895,501 Cash and cash equivalents 701,289 635,047 Restricted cash and cash equivalents 20,013 15,908 Investments in consolidated subsidiaries 16,699,125 14,928,756 Other assets 450,327 441,977 Total Assets $ 21,475,747 $ 18,917,189 LIABILITIES AND SHAREHOLDERS' EQUITY Senior long-term debt $ 4,032,960 $ 3,439,197 Income taxes payable 179,381 213,770 Net deferred tax liability 274,661 201,140 Other liabilities 72,847 79,154 Total Liabilities 4,559,849 3,933,261 Shareholders' equity: Preferred stock 591,891 591,891 Common stock 3,560,633 3,517,146 Retained earnings 13,380,456 11,353,101 Accumulated other comprehensive loss (617,082) (478,210) Total Shareholders' Equity 16,915,898 14,983,928 Total Liabilities and Shareholders' Equity $ 21,475,747 $ 18,917,189 CONDENSED STATEMENTS OF INCOME (LOSS) AND COMPREHENSIVE INCOME (LOSS) Years Ended December 31, 2024 2023 2022 (dollars in thousands) REVENUES Net investment income $ 86,583 $ 92,080 $ 34,781 Dividends on common stock of consolidated subsidiaries 575,008 310,000 278,557 Net investment gains (losses): Net realized investment gains (losses) 16,718 (515) 7,620 Change in fair value of equity securities 342,623 275,048 (397,906) Net investment gains (losses) 359,341 274,533 (390,286) Gain on sale of subsidiary — — 107,293 Other revenues (losses) 31,132 (28,718) (29,487) Total Revenues 1,052,064 647,895 858 EXPENSES Interest expense 179,626 156,953 172,125 Other expenses 12,061 19,716 111,848 Net foreign exchange losses (gains) (36,907) 9,038 (13,143) Total Expenses 154,780 185,707 270,830 Income (Loss) Before Equity in Undistributed Earnings (Losses) of Consolidated Subsidiaries and Income Taxes 897,284 462,188 (269,972) Equity in undistributed earnings (losses) of consolidated subsidiaries 1,941,339 1,580,347 (72,125) Income tax (expense) benefit (91,601) (46,475) 125,820 Net Income (Loss) to Shareholders 2,747,022 1,996,060 (216,277) Preferred stock dividends (36,000) (36,000) (36,000) Net Income (Loss) to Common Shareholders $ 2,711,022 $ 1,960,060 $ (252,277) OTHER COMPREHENSIVE INCOME (LOSS) TO SHAREHOLDERS Change in net unrealized gains (losses) on available-for-sale investments, net of taxes: Net holding gains (losses) arising during the period $ 109 $ 1,453 $ (24,465) Consolidated subsidiaries' net holding gains (losses) arising during the period (148,411) 276,910 (1,175,271) Reclassification adjustments for net gains (losses) included in net income (loss) to shareholders 365 (92) 1,965 Consolidated subsidiaries' reclassification adjustments for net losses included in net income (loss) to shareholders 17,642 28,632 42,941 Change in net unrealized gains (losses) on available-for-sale investments, net of taxes (130,295) 306,903 (1,154,830) Consolidated subsidiaries' change in discount rate for life and annuity benefits, net of taxes 252 (22,343) 149,874 Consolidated subsidiaries' change in foreign currency translation adjustments, net of taxes (3,883) 4,650 (9,276) Consolidated subsidiaries' change in net actuarial pension loss, net of taxes (4,946) 74 24,730 Total Other Comprehensive Income (Loss) to Shareholders (138,872) 289,284 (989,502) Comprehensive Income (Loss) to Shareholders $ 2,608,150 $ 2,285,344 $ (1,205,779) CONDENSED STATEMENTS OF CASH FLOWS Years Ended December 31, 2024 2023 2022 (dollars in thousands) OPERATING ACTIVITIES Net income (loss) to shareholders $ 2,747,022 $ 1,996,060 $ (216,277) Adjustments to reconcile net income (loss) to shareholders to net cash provided by operating activities (2,183,635) (1,664,382) 489,413 Net Cash Provided By Operating Activities 563,387 331,678 273,136 INVESTING ACTIVITIES Proceeds from sales, maturities, calls and prepayments of fixed maturity securities 14,459 72,834 13,047 Cost of fixed maturity securities purchased (6,516) (48,501) — Proceeds from sales of equity securities 3,662 24,237 65,379 Cost of equity securities purchased (310) (7,731) (16,660) Net change in short-term investments (315,622) 451,846 58,970 Decrease (increase) in notes receivable due from subsidiaries — — 75,645 Capital contributions to subsidiaries (174,002) (55,575) (94,585) Proceeds from sale of subsidiary — 16,090 165,615 Cost of equity method investments — (5,000) — Other 2,694 (12,691) 4,779 Net Cash Provided (Used) By Investing Activities (475,635) 435,509 272,190 FINANCING ACTIVITIES Repayment of senior long-term debt — (250,000) (350,000) Additions to senior long-term debt 592,596 — — Decrease in notes payable to subsidiaries — — (32,753) Repurchases of common stock (572,728) (445,479) (290,796) Dividends paid on preferred stock (36,000) (36,000) (36,000) Other (1,273) — — Net Cash Used By Financing Activities (17,405) (731,479) (709,549) Increase (decrease) in cash, cash equivalents, restricted cash and restricted cash equivalents 70,347 35,708 (164,223) Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of year 650,955 615,247 779,470 CASH, CASH EQUIVALENTS, RESTRICTED CASH AND RESTRICTED CASH EQUIVALENTS AT END OF YEAR $ 721,302 $ 650,955 $ 615,247 SUPPLEMENTAL CASH FLOW INFORMATION Cash dividends received from subsidiaries $ 575,000 $ 310,000 $ 245,102 Non-cash capital contributions to subsidiaries $ — $ 43,111 $ 923,980 Note to Condensed Financial Information of Markel Group Inc. (Parent Company Only) Basis of Presentation . The parent company financial information note should be read in conjunction with the consolidated financial statements and other notes included herein. For purposes of this condensed financial information, the Company's wholly owned and majority owned subsidiaries are recorded based upon its proportionate share of the subsidiaries' net assets. Debt . All of the Company's senior long-term debt was issued and is held by Markel Group. Markel Group also is party to a revolving credit facility. There were no borrowings outstanding under this revolving credit facility at December 31, 2024 and 2023. See note 14 for further details about Markel Group's revolving credit facility and senior long-term debt, including a five-year schedule of debt maturities. Guarantees . Markel Group has guaranteed intercompany loans to Markel Ventures, Inc. from certain insurance subsidiaries of Markel Group. The outstanding loan balances totaled $788.0 million and $738.0 million as of December 31, 2024 and 2023, respectively, all of which was eliminated in consolidation. Additionally, Markel Group guarantees any obligations under the revolving credit facility of its insurance subsidiaries that are parties to the related credit agreement, however, there were no borrowings outstanding at December 31, 2024 and 2023. Markel Group has also made certain guarantees on other financial obligations, including leases, for other subsidiaries, which, individually and in the aggregate, were not material to Markel Group.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2024
Subsequent Events [Abstract]
Subsequent Events	24 . Subsequent Event In January 2025, there was a series of wildfires in southern California. Based on information currently available, the Company estimates its range of underwriting losses, including the impact of reinstatement premiums, from these events to be between $90 million and $130 million, before income taxes. This estimated range of losses was derived based on a review of in-force contracts and an analysis of ceded reinsurance contracts, as well as preliminary industry loss estimates. Due to the inherent uncertainty associated with the nature of these wildfire events and limited claims activity, the Company's underwriting loss estimates are subject to a wide range of variability. The Company will refine its estimate of net losses, which will be recorded in the first quarter of 2025, as more details about these events and actual level of claims emerge.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net income (loss) to shareholders	$ 2,747,022	$ 1,996,060	$ (216,277)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Summary Of Significant Accoun_2

Summary Of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	a) Basis of Presentation. 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 any 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.
Use of Estimates	b) Use of Estimates. 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. Management periodically reviews its estimates and assumptions. Quarterly reviews include evaluating the adequacy of reserves for unpaid losses and loss adjustment expenses and contingencies. Estimates and assumptions for goodwill and intangible assets are reviewed in conjunction with an acquisition, and goodwill and indefinite-lived intangible assets are reassessed at least annually for impairment. Actual results may differ materially from the estimates and assumptions used in preparing the consolidated financial statements.
Investments	c) Investments. Available-for-sale investments and equity securities are recorded at estimated fair value. Available-for-sale investments include fixed maturity securities and short-term investments. Fixed maturity securities include government and municipal bonds and mortgage-backed securities with original maturities of more than one year. Short-term investments are primarily comprised of treasury bills with original maturities of one year or less. Realized investment gains or losses on available-for-sale investments are included in net income. Realized gains or losses from sales of available-for-sale investments are derived using the first-in, first-out method on the trade date. Unrealized gains and losses on available-for-sale investments, net of income taxes, are included in other comprehensive income. The Company completes a detailed analysis each quarter to assess declines in the fair value of its available-for-sale investments. Any credit-related impairment losses on the Company's available-for-sale investments are recorded as an allowance, subject to reversal, and recognized in net income. Realized and unrealized gains and losses on equity securities are included in net income as net investment gains or losses. Premiums and discounts are amortized or accreted over the lives of the related fixed maturity securities as an adjustment to the yield using the effective interest method. Dividend and interest income are recognized when earned. Accrued interest receivable is excluded from both the estimated fair value and the amortized cost basis of available-for-sale securities and included within other assets on the Company's consolidated balance sheets. Any uncollectible accrued interest receivable is written off in the period it is deemed uncollectible. See note 4 and note 5 for further details regarding the Company's investment portfolio.
Cash and Cash Equivalents	d) Cash and Cash Equivalents. The Company considers all investments with original maturities of 90 days or less to be cash equivalents, with the exception of treasury bills, which are classified as short-term investments. The carrying value of the Company's cash and cash equivalents approximates fair value.
Restricted Cash and Cash Equivalents	e) Restricted Cash and Cash Equivalents. Cash and cash equivalents that are restricted as to withdrawal or use are recorded as restricted cash and cash equivalents. The carrying value of the Company's restricted cash and cash equivalents approximates fair value.
Receivables	f) Receivables. Receivables include amounts receivable from agents, brokers and insureds, which represent premiums that are both currently due and amounts not yet due on insurance and reinsurance policies. Premiums for insurance policies are generally due at inception. Premiums for reinsurance policies generally become due over the period of coverage based on the policy terms. Changes in the estimate of reinsurance premiums written will result in an adjustment to premiums receivable in the period they are determined. Receivables also include amounts receivable from contracts with customers, which represent the Company's unconditional right to consideration for satisfying the performance obligations outlined in the contract. The Company monitors credit risk associated with receivables, taking into consideration the fact that in certain instances in the Company's insurance operations credit risk may be reduced by the Company's right to offset loss obligations or unearned premiums against premiums receivable. An allowance is established for credit losses expected to be incurred over the life of the receivable, which is recorded net of this allowance. The allowance is charged to net income in the period the receivable is recorded and revised in subsequent periods to reflect changes in the Company's estimate of expected credit losses. See note 7 for further details regarding receivables.
Reinsurance Recoverables	g) Reinsurance Recoverables. Amounts recoverable from reinsurers are estimated in a manner consistent with the claim liability associated with the reinsured business. The Company evaluates the financial condition of its reinsurers and monitors concentration of credit risk to minimize its exposure to significant losses from individual reinsurers. To further reduce credit exposure on reinsurance recoverables, the Company has received collateral, including letters of credit and trust accounts, from certain reinsurers. Cash collateral related to these reinsurance agreements is available, without restriction, when the Company pays losses covered by the reinsurance agreements. An allowance is established for credit losses expected to be incurred over the life of the reinsurance recoverable, which is recorded net of this allowance. The allowance is charged to net income in the period the recoverable is recorded and revised in subsequent periods to reflect changes in the Company's estimate of expected credit losses. As of December 31, 2024 and 2023, the allowance for credit losses associated with the Company's reinsurance recoverables was not material to the consolidated financial statements.
Deferred Policy Acquisition Costs	h) Deferred Policy Acquisition Costs. Costs directly related to the acquisition of insurance premiums are deferred and amortized over the related policy period, generally one year. The Company only defers acquisition costs incurred that are directly related to the successful acquisition of new or renewal insurance contracts, including commissions to agents and brokers, salaries and benefits and premium taxes. Commissions received related to reinsurance premiums ceded are netted against broker commissions in determining acquisition costs eligible for deferral. To the extent that future policy revenues on existing policies are not adequate to cover related costs and expenses, deferred policy acquisition costs are charged to earnings. The Company does not consider anticipated investment income in determining whether a premium deficiency exists. See note 2(a) and (g) for further details regarding policy acquisition costs.
Goodwill and Intangible Assets	i) Goodwill and Intangible Assets. Goodwill and intangible assets are recorded as a result of business acquisitions. Goodwill represents the excess of the amount paid to acquire a business over the net fair value of assets acquired and liabilities assumed at the date of acquisition. Indefinite-lived and other intangible assets are recorded at fair value as of the acquisition date. The determination of the fair value of certain assets acquired and liabilities assumed involves significant judgment and the use of valuation models and other estimates, which require assumptions that are inherently subjective. Goodwill and indefinite-lived intangible assets are tested for impairment at least annually. The Company completes an annual test during the fourth quarter of each year based upon the results of operations through September 30. Intangible assets with definite lives are amortized using the straight-line method over their estimated useful lives, generally five
Equity Method Investments	j) Equity Method Investments. The Company holds certain investments that are required to be accounted for under the equity method, whereby they initially are recorded at cost within other assets on the consolidated balance sheets and subsequently increased or decreased by the Company's proportionate share of the net income or loss of the investee and other transactions impacting the investee's equity. The Company records its proportionate share of net income or loss of the investee in services and other revenues. The Company records its proportionate share of other comprehensive income or loss of the investee as a component of other comprehensive income. Dividends or other equity distributions in excess of the Company's cumulative equity in earnings of the investee are recorded as a reduction of the investment. The Company reviews equity method investments for impairment when events or circumstances indicate that a decline in the fair value of the investment below its carrying value is other-than-temporary. See note 6 for further details regarding the Company's equity method investments.
Property and Equipment	k) Property and Equipment. Property and equipment is maintained primarily by certain of the Company's Markel Ventures businesses and is stated at cost less accumulated depreciation. Depreciation of property and equipment is calculated using the straight-line method over the estimated useful lives of the respective assets. Property and equipment, net of accumulated depreciation, was $1.4 billion and $1.3 billion as of December 31, 2024 and 2023, respectively, and is included in other assets on the Company's consolidated balance sheets.
Leases	l) Leases. The present value of future lease payments for the Company's leases with terms greater than 12 months is included on the consolidated balance sheets as lease liabilities and right-of-use lease assets within other liabilities and other assets, respectively. The Company's lease portfolio primarily consists of operating leases for real estate and equipment. Total expected lease payments are based on the lease payments specified in the contract and the stated term, including any options to extend or terminate that the Company is reasonably certain to exercise. The Company accounts for lease components and any associated non-lease components within a contract as a single lease component, and therefore allocates all of the expected lease payments to the lease component. The lease liability, which represents the Company's contractual obligation to make lease payments, is calculated based on the present value of expected lease payments over the remaining lease term, discounted using the Company's collateralized incremental borrowing rate at the lease commencement date. The lease liability is then adjusted for any prepaid rent, lease incentives received or capitalized initial direct costs to determine the lease asset, which represents the Company's right to use the underlying asset for the lease term. Total lease costs are primarily comprised of rental expense for operating leases, which is recognized on a straight line basis over the lease term. Rental expense attributable to the Company's underwriting operations is included in underwriting, acquisition and insurance expenses and rental expense attributable to the Company's other operations is included in products expenses and services and other expenses in the consolidated statements of income and comprehensive income. See note 9 for further details regarding leases.
Inventories	m) Inventories. Inventories are maintained at certain of the Company's Markel Ventures businesses and consist primarily of raw materials, work-in-process and finished goods. Inventories are generally valued based on the nature of the inventory, including the first-in-first-out, standard cost and specific identification methods, and stated at the lower of cost or net realizable value. Inventories were $631.5 million and $617.2 million as of December 31, 2024 and 2023, respectively, and are included in other assets on the Company's consolidated balance sheets.
Redeemable Noncontrolling Interests	n) Redeemable Noncontrolling Interests. The Company owns controlling interests in various companies through its Markel Ventures operations. In some cases, the Company has the option to acquire the remaining equity interests, and the remaining equity interests have the option to sell their interests to the Company, in the future. The redemption value of the remaining equity interests is generally based on the respective company's earnings in specified periods preceding the redemption date. The redeemable noncontrolling interests are redeemable in 2025 or become redeemable between 2026 and 2032. The Company recognizes changes in the redemption value that exceed the carrying value of redeemable noncontrolling interests to retained earnings as if the balance sheet date was also the redemption date. Changes in the redemption value also result in an adjustment to net income to common shareholders in the calculation of basic and diluted net income per common share. See note 19 for further details regarding the calculation of basic and diluted net income per common share.
Income Taxes	o) Income Taxes.
Unpaid Losses and Loss Adjustment Expenses	p) Unpaid Losses and Loss Adjustment Expenses. Unpaid losses and loss adjustment expenses on the Company's property and casualty insurance business are based on evaluations of reported claims and estimates for losses and loss adjustment expenses incurred but not reported (IBNR). Estimates for losses and loss adjustment expenses incurred but not reported are
Life and Annuity Benefits	q) Life and Annuity Benefits.
Revenue Recognition	r) Revenue Recognition. Property and Casualty Premiums Insurance premiums written are generally recorded at the inception of a policy and earned on a pro rata basis over the policy period, typically one year. The cost of reinsurance ceded is initially recorded as prepaid reinsurance premiums and is amortized over the reinsurance contract period in proportion to the amount of insurance protection provided. Premiums ceded are netted against premiums written. For multi-year contracts where insurance premiums are payable in annual installments, written premiums are recorded at the inception of the contract based on management's best estimate of total premiums to be received. For contracts where the cedent has the ability to unilaterally commute or cancel coverage within the term of the policy, written premiums are generally recorded on an annual basis or up to the contract cancellation point. The remaining premiums are estimated and included as written at each successive anniversary date within the multi-year term. Assumed reinsurance premiums are recorded at the inception of each contract based upon contract terms and information received from cedents and brokers and are earned on a pro rata basis over the coverage period, or for multi-year contracts, in proportion with the underlying risk exposure to the extent there is variability in the exposure through the coverage period. Changes in reinsurance premium estimates are expected and may result in significant adjustments in any period. These estimates change over time as additional information regarding changes in underlying exposures is obtained. Any subsequent differences arising on such estimates are recorded as premiums written in the period they are determined and are earned on a pro rata basis over the coverage period, or immediately if the coverage period has ended. The Company uses the periodic method to account for assumed reinsurance from foreign reinsurers as a result of the sufficiency of the information provided by the reinsurer, which is consistent with its accounting for assumed reinsurance from U.S. reinsurers. Certain contracts that the Company writes provide for reinstatement of coverage. Reinstatement premiums are the premiums for the restoration of the insurance or reinsurance limit of a contract to its full amount after a loss occurrence by the insured or reinsured. The Company accrues for reinstatement premiums resulting from losses recorded. Such accruals are based upon contractual terms and management judgment is involved with respect to the amount of losses recorded. Changes in estimates of losses recorded on contracts with reinstatement premium features will result in changes in reinstatement premiums based on contractual terms. Reinstatement premiums are recognized as premiums written at the time losses are recorded and are generally earned on a pro rata basis over the remaining coverage period. Other Revenues Other revenues primarily relate to the Company's Markel Ventures, program services and insurance-linked securities (ILS) operations and consist of revenues from the sale of products and services. Revenues are recognized when, or as, control of the promised goods or services is transferred to the Company's customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. Contracts with customers generally have an original term of one year or less. For contracts with customers that have an original term greater than one year, the Company recognizes revenue at the amount for which it has a right to invoice for the products delivered or services performed. Certain customers may receive volume rebates or credits for products and services, which are accounted for as variable consideration. The Company estimates these amounts based on the expected amount to be provided to the customer and reduces revenues recognized by a corresponding amount. The Company does not expect significant changes to its estimates of variable consideration over the term of the contracts. Payment terms for products and services vary by the type of product or service offered and the location of the customer, and payment is typically received at or shortly after the point of sale. For certain products, the Company requires partial payment in the form of a deposit before the products are delivered to the customer, which is included in other liabilities on the Company's consolidated balance sheets. Through its Markel Ventures operations, the Company has several different businesses that manufacture or produce a variety of products, including ornamental plants, precast concrete, equipment used in baking systems, over-the-road transportation equipment, portable dredges, residential homes and flooring for the trucking industry. Most of the Company's product revenues are recognized when the products are shipped to the customer or the products arrive at the agreed upon destination with the end customer. Certain of the Company's products revenues are recognized based on percentage of completion. Some of the Company's contracts include multiple performance obligations. For such arrangements, revenues are allocated to each performance obligation based on the relative standalone selling price, which is derived from amounts stated in the contract. Through its Markel Ventures operations, the Company also has several different businesses that provide various types of services, including distribution of exterior building products, fire protection and life safety services and consulting services. Service revenues are generally recognized either at a point-in-time when services are provided or over the term of the contracts based on hours incurred or as services are provided. The Company's Markel Ventures operations also include certain businesses that earn revenues through the leasing of equipment. The revenues from these leases are generally recognized on a straight-line basis over the term of the lease. The Company's other revenues also include fronting fees, or ceding fees, which are based on the gross premiums written on behalf of general agent and capacity provider clients. Ceding fees are earned in a manner consistent with the recognition of the gross premiums earned on the underlying insurance policies, generally on a pro rata basis over the terms of the underlying policies reinsured. The Company's other revenues also include investment management fee income. Investment management fee income is recognized over the period in which investment management services are provided and is calculated and recognized monthly, based on either the net asset value of the accounts managed or gross premium volume for the underlying risks. For certain accounts, the Company is also entitled to participate, on a fixed-percentage basis, in any net income generated in excess of an agreed-upon threshold as established by the underlying investment management agreements. In general, net income is calculated at the end of each calendar year and incentive fees are payable annually. Incentive fee income is recognized at the conclusion of the contractual performance period, when the uncertainty related to performance has been resolved. See note 10 for further details regarding products, services and other revenues.
Other Revenues	Other Revenues Other revenues primarily relate to the Company's Markel Ventures, program services and insurance-linked securities (ILS) operations and consist of revenues from the sale of products and services. Revenues are recognized when, or as, control of the promised goods or services is transferred to the Company's customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. Contracts with customers generally have an original term of one year or less. For contracts with customers that have an original term greater than one year, the Company recognizes revenue at the amount for which it has a right to invoice for the products delivered or services performed. Certain customers may receive volume rebates or credits for products and services, which are accounted for as variable consideration. The Company estimates these amounts based on the expected amount to be provided to the customer and reduces revenues recognized by a corresponding amount. The Company does not expect significant changes to its estimates of variable consideration over the term of the contracts. Payment terms for products and services vary by the type of product or service offered and the location of the customer, and payment is typically received at or shortly after the point of sale. For certain products, the Company requires partial payment in the form of a deposit before the products are delivered to the customer, which is included in other liabilities on the Company's consolidated balance sheets. Through its Markel Ventures operations, the Company has several different businesses that manufacture or produce a variety of products, including ornamental plants, precast concrete, equipment used in baking systems, over-the-road transportation equipment, portable dredges, residential homes and flooring for the trucking industry. Most of the Company's product revenues are recognized when the products are shipped to the customer or the products arrive at the agreed upon destination with the end customer. Certain of the Company's products revenues are recognized based on percentage of completion. Some of the Company's contracts include multiple performance obligations. For such arrangements, revenues are allocated to each performance obligation based on the relative standalone selling price, which is derived from amounts stated in the contract. Through its Markel Ventures operations, the Company also has several different businesses that provide various types of services, including distribution of exterior building products, fire protection and life safety services and consulting services. Service revenues are generally recognized either at a point-in-time when services are provided or over the term of the contracts based on hours incurred or as services are provided. The Company's Markel Ventures operations also include certain businesses that earn revenues through the leasing of equipment. The revenues from these leases are generally recognized on a straight-line basis over the term of the lease. The Company's other revenues also include fronting fees, or ceding fees, which are based on the gross premiums written on behalf of general agent and capacity provider clients. Ceding fees are earned in a manner consistent with the recognition of the gross premiums earned on the underlying insurance policies, generally on a pro rata basis over the terms of the underlying policies reinsured. The Company's other revenues also include investment management fee income. Investment management fee income is recognized over the period in which investment management services are provided and is calculated and recognized monthly, based on either the net asset value of the accounts managed or gross premium volume for the underlying risks. For certain accounts, the Company is also entitled to participate, on a fixed-percentage basis, in any net income generated in excess of an agreed-upon threshold as established by the underlying investment management agreements. In general, net income is calculated at the end of each calendar year and incentive fees are payable annually. Incentive fee income is recognized at the conclusion of the contractual performance period, when the uncertainty related to performance has been resolved. See note 10 for further details regarding products, services and other revenues.
Program Services	s) Program Services. In connection with its program services business, the Company enters into contractual agreements with both producing general agents and reinsurers, whereby the general agents and reinsurers are typically obligated to each other for payment of insurance amounts, including premiums, commissions and losses. To the extent these funds are not the obligation of the Company and are settled directly between the general agent and the reinsurer, no receivables or payables are recorded for these amounts. All obligations of the Company's insurance subsidiaries owed to or on behalf of their policyholders are recorded by the Company and, to the extent appropriate, offsetting reinsurance recoverables are recorded.
Foreign Currency Transactions	t) Foreign Currency Transactions. The U.S. Dollar is the Company's reporting currency and the primary functional currency of its foreign underwriting operations. The functional currencies of the Company's other foreign operations are the currencies of the primary economic environments in which the majority of their business is transacted. Foreign currency transaction gains and losses are the result of exchange rate changes on transactions denominated in currencies other than the functional currency at each foreign entity. Monetary assets and liabilities are remeasured to the functional currency at current exchange rates, with resulting gains and losses included in net foreign exchange gains within net income. Non-monetary assets and liabilities are remeasured to the functional currency at historic exchange rates. Available-for-sale securities are recorded at fair value with resulting gains and losses, including the portion attributable to movements in exchange rates, included in the change in net unrealized gains on available-for-sale investments, net of taxes within other comprehensive income. While the Company attempts to naturally hedge its exposure to foreign currency fluctuations by matching assets and liabilities in the same currencies, there is a financial statement mismatch between the gains or losses recorded in net income related to insurance reserves denominated in non-functional currencies and the gains or losses recorded in other comprehensive income related to the available-for-sale securities held in non-functional currencies supporting the reserves.
Comprehensive Income	u) Comprehensive Income. Comprehensive income represents all changes in equity that result from recognized transactions and other economic events during the period. Other comprehensive income refers to revenues, expenses, gains and losses that under U.S. GAAP are included in comprehensive income but excluded from net income, such as unrealized gains or losses on available-for-sale investments, changes in discount rate for life and annuity benefits, foreign currency translation adjustments and changes in net actuarial pension loss. See note 20 for further details regarding other comprehensive income.
Net Income Per Common Share	v) Net Income Per Common Share. Basic net income per common share is computed by dividing adjusted net income to shareholders by the weighted average number of common shares outstanding during the year. Diluted net income per common share is computed by dividing adjusted net income to shareholders by the sum of the weighted average number of common shares and dilutive potential common shares outstanding during the year. See note 19 for further details regarding the calculation of basic and diluted net income per common share.
Variable Interest Entities	w) Variable Interest Entities. The Company determines whether it has relationships with entities defined as VIEs in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 810, Consolidation . Under this guidance, a VIE is consolidated by the variable interest holder that is determined to be the primary beneficiary. An entity in which the Company holds a variable interest is a VIE if any of the following conditions exist: (a) the total equity investment at risk is not sufficient to permit the entity to finance its activities without additional subordinated financial support, (b) as a group, the holders of equity investment at risk lack either the direct or indirect ability through voting rights or similar rights to make decisions about an entity's activities that most significantly impact the entity's economic performance or the obligation to absorb the expected losses or right to receive the expected residual returns, or (c) the voting rights of some investors are disproportionate to their obligation to absorb the expected losses of the entity, their rights to receive the expected residual returns of the entity, or both and substantially all of the entity's activities either involve or are conducted on behalf of an investor with disproportionately few voting rights. The primary beneficiary is defined as the variable interest holder that is determined to have the controlling financial interest as a result of having both (a) the power to direct the activities of a VIE that most significantly impact the economic performance of the VIE and (b) the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE.
Recent Accounting Pronouncements	x) Recent Accounting Pronouncements. Accounting Standards Adopted in 2024 In November 2023, the 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 became effective for the Company's 2024 Annual Report on Form 10-K and was applied using a retrospective approach that required recasting of all prior periods presented. The standard only impacts required disclosures and does not impact the Company's financial position, results of operations or cash flows. The ASU did not result in significant changes to the Company's reportable segment disclosures. See note 2 for the Company's segment disclosures. Accounting Standards Not Yet Adopted 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 will not impact the Company's financial position, results of operations or cash flows. In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures.

Segment Reporting Disclosures (

Segment Reporting Disclosures (Tables)	12 Months Ended
	Dec. 31, 2024
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Company's Segment Disclosures	a) The following tables summarize the Company's segment disclosures. Year Ended December 31, 2024 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures Other insurance operations Corporate Consolidated Earned premiums $ 7,407,643 $ 1,028,201 $ — $ — $ (3,432) $ — $ 8,432,412 Net investment income — — 913,478 7,018 — — 920,496 Net investment gains — — 1,807,219 — — — 1,807,219 Products revenues — — — 2,635,659 — — 2,635,659 Services and other revenues — — 52,253 2,477,419 295,305 — 2,824,977 Total operating revenues 7,407,643 1,028,201 2,772,950 5,120,096 291,873 — 16,620,763 Losses and loss adjustment expenses: Current accident year - attritional (4,704,219) (733,191) — — — — (5,437,410) Current accident year - catastrophe (67,169) (3,480) — — — — (70,649) Prior accident years 451,016 12,344 — — (8,050) — 455,310 Underwriting, acquisition and insurance expenses: Amortization of policy acquisition costs (1,501,829) (252,312) — — — — (1,754,141) Other underwriting expenses (1,163,557) (56,925) — — (2,766) — (1,223,248) Products expenses — — — (2,272,219) — — (2,272,219) Services and other expenses — — — (2,327,795) (96,577) — (2,424,372) Amortization of acquired intangible assets (181,472) (181,472) Operating income (loss) $ 421,885 $ (5,363) $ 2,772,950 $ 520,082 $ 184,480 $ (181,472) $ 3,712,562 Interest expense (204,300) Net foreign exchange gains 129,438 Income before income taxes $ 3,637,700 Year Ended December 31, 2023 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures Other insurance operations Corporate Consolidated Earned premiums $ 7,282,705 $ 1,014,294 $ — $ — $ (1,520) $ — $ 8,295,479 Net investment income — — 729,219 5,313 — — 734,532 Net investment gains — — 1,524,054 — — — 1,524,054 Products revenues — — — 2,545,053 — — 2,545,053 Services and other revenues — — (11,854) 2,434,715 281,651 — 2,704,512 Total operating revenues 7,282,705 1,014,294 2,241,419 4,985,081 280,131 — 15,803,630 Losses and loss adjustment expenses: Current accident year - attritional (4,651,173) (669,314) — — — — (5,320,487) Current accident year - catastrophe (39,572) (500) — — — — (40,072) Prior accident years 104,743 (57,081) — — (9,112) — 38,550 Underwriting, acquisition and insurance expenses: Amortization of policy acquisition costs (1,508,169) (255,501) — — — — (1,763,670) Other underwriting expenses (1,026,358) (51,163) — — 457 — (1,077,064) Products expenses — — — (2,220,676) — — (2,220,676) Services and other expenses — — — (2,244,527) (66,242) — (2,310,769) Amortization of acquired intangible assets (180,614) (180,614) Operating income (loss) $ 162,176 $ (19,265) $ 2,241,419 $ 519,878 $ 205,234 $ (180,614) $ 2,928,828 Interest expense (185,077) Net foreign exchange losses (90,045) Income before income taxes $ 2,653,706 Year Ended December 31, 2022 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures Other insurance operations Corporate Consolidated Earned premiums $ 6,528,263 $ 1,063,347 $ — $ — $ (3,818) $ — $ 7,587,792 Net investment income — — 445,846 909 — — 446,755 Net investment losses — — (1,595,733) — — — (1,595,733) Products revenues — — — 2,427,096 — — 2,427,096 Services and other revenues — — (17,661) 2,329,522 497,564 — 2,809,425 Total operating revenues 6,528,263 1,063,347 (1,167,548) 4,757,527 493,746 — 11,675,335 Losses and loss adjustment expenses: Current accident year - attritional (3,867,195) (663,903) — — — — (4,531,098) Current accident year - events (1) (69,230) (12,707) — — — — (81,937) Prior accident years 142,924 26,052 — — (1,530) — 167,446 Underwriting, acquisition and insurance expenses: Amortization of policy acquisition costs (1,375,539) (279,567) — — — — (1,655,106) Other underwriting expenses (809,352) (49,363) — — (1,762) — (860,477) Products expenses — — — (2,241,736) — — (2,241,736) Services and other expenses — — — (2,111,510) (195,475) — (2,306,985) Amortization of acquired intangible assets (178,778) (178,778) Impairment of goodwill (80,000) (80,000) Operating income (loss) $ 549,871 $ 83,859 $ (1,167,548) $ 404,281 $ 294,979 $ (258,778) $ (93,336) Interest expense (196,062) Net foreign exchange gains 137,832 Loss before income taxes $ (151,566) (1) Includes losses and loss adjustment expenses attributed to catastrophes and the Russia-Ukraine conflict.
Summary of Additional Measures for Markel Ventures	b) The following amounts attributable to the Markel Ventures segment are also reviewed, or included in measures reviewed, by the Company's chief operating decision maker. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Depreciation expense $ 122,125 $ 108,605 $ 102,055 Capital expenditures $ 177,075 $ 221,036 $ 225,230
Reconciliation Of Segment Assets To The Company's Consolidated Balance Sheets	c) The following table reconciles segment assets to the Company's consolidated balance sheets. December 31, (dollars in thousands) 2024 2023 Segment assets: Investing $ 34,272,049 $ 30,542,282 Underwriting 10,784,528 9,897,689 Markel Ventures 5,824,229 5,519,542 Total segment assets 50,880,806 45,959,513 Other insurance operations 11,017,176 9,086,197 Total assets $ 61,897,982 $ 55,045,710
Underwriting Schedule Of Product Information	d) The following table summarizes earned premiums by major product grouping within each underwriting segment. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Insurance segment: General liability $ 2,063,827 $ 2,128,317 $ 1,927,721 Professional liability 1,655,848 1,798,882 1,739,983 Marine and energy 747,004 688,591 585,885 Personal lines 625,542 538,816 489,648 Property 609,453 532,337 428,563 Programs 576,444 509,866 384,952 Workers' compensation 374,371 393,011 385,054 Credit and surety 248,001 219,542 193,701 Other products 507,153 473,343 392,756 Total Insurance 7,407,643 7,282,705 6,528,263 Reinsurance segment: General liability 382,151 368,376 382,482 Professional liability 371,198 388,610 398,839 Specialty 269,021 245,126 275,033 Property 5,831 12,182 6,993 Total Reinsurance 1,028,201 1,014,294 1,063,347 Other (3,432) (1,520) (3,818) Total earned premiums $ 8,432,412 $ 8,295,479 $ 7,587,792 The Company does not manage products at this level of aggregation as it offers a diverse portfolio of products and manages these products in more disaggregated groupings within each underwriting segment.
Summary of Top Five Independent Brokers Concentration	The following table summarizes the percentage of gross written premiums placed by the top five independent brokers within the Company's underwriting operations, Insurance segment and Reinsurance segment. The top five independent brokers may vary among the segments and from year to year. Years Ended December 31, 2024 2023 2022 Insurance segment 32 % 33 % 34 % Reinsurance segment 90 % 95 % 99 % Total underwriting 38 % 37 % 40 %
Schedule of Gross Premium Volume and Net Written Premiums, by Segment	e) The following table summarizes gross and net written premiums by segment, including a reconciliation to total underwriting and consolidated amounts. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Gross written premium: Insurance segment $ 9,400,316 $ 9,217,150 $ 8,606,700 Reinsurance segment 1,150,780 1,046,539 1,229,851 Other underwriting 777 13,943 10,987 Total underwriting 10,551,873 10,277,632 9,847,538 Program services and ILS fronting 4,942,758 3,724,605 3,354,144 Total $ 15,494,631 $ 14,002,237 $ 13,201,682 Net written premium: Insurance segment $ 7,260,089 $ 7,432,062 $ 7,040,176 Reinsurance segment 1,039,372 967,799 1,167,312 Other underwriting 290 (1,073) (115) Total underwriting 8,299,751 8,398,788 8,207,373 Program services and ILS fronting (3,576) (1,213) (3,983) Total $ 8,296,175 $ 8,397,575 $ 8,203,390
Summary Of Deferred Policy Acquisition Costs, Unearned Premiums And Unpaid Losses And Loss Adjustment Expenses	f) The following table summarizes deferred policy acquisition costs, unearned premiums and unpaid losses and loss adjustment expenses by segment, including a reconciliation to total underwriting and consolidated amounts. (dollars in thousands) Deferred Policy Unearned Unpaid Losses and December 31, 2024 Insurance segment $ 648,969 $ 4,283,879 $ 16,073,355 Reinsurance segment 226,741 933,329 3,870,059 Other underwriting — 1,558 149,522 Total underwriting 875,710 5,218,766 20,092,936 Program services and ILS fronting — 1,845,190 6,515,153 Markel CATCo Re (see note 17) — — 25,005 Total $ 875,710 $ 7,063,956 $ 26,633,094 December 31, 2023 Insurance segment $ 708,128 $ 4,307,704 $ 14,221,258 Reinsurance segment 223,216 901,138 3,726,472 Other underwriting — 7,488 165,071 Total underwriting 931,344 5,216,330 18,112,801 Program services and ILS fronting — 1,426,096 5,185,553 Markel CATCo Re (see note 17) — — 184,967 Total $ 931,344 $ 6,642,426 $ 23,483,321
Markel Ventures Schedule Of Product Information	g) The following table summarizes total products revenues and services and other revenues by major product and service grouping within the Company's Markel Ventures segment. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Products: Consumer and building $ 1,606,353 $ 1,474,499 $ 1,510,130 Transportation-related 584,200 667,040 612,467 Equipment manufacturing 445,106 403,514 304,499 Total products revenues 2,635,659 2,545,053 2,427,096 Services and other: Construction 2,089,280 2,042,326 1,910,403 Consulting 283,343 297,115 326,549 Other 104,796 95,274 92,570 Total services and other revenues 2,477,419 2,434,715 2,329,522 Total products revenues and services and other revenues $ 5,113,078 $ 4,979,768 $ 4,756,618

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Available-For-Sale Investments	a) The following tables summarize the Company's available-for-sale investments. Agency 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. December 31, 2024 (dollars in thousands) Amortized Gross Gross Estimated Fixed maturity securities: U.S. Treasury securities $ 5,147,365 $ 8,962 $ (68,469) $ 5,087,858 U.S. government-sponsored enterprises 1,445,171 2,976 (101,911) 1,346,236 Obligations of states, municipalities and political subdivisions 3,813,146 5,866 (199,520) 3,619,492 Foreign governments, agencies and supranationals 2,909,561 4,264 (207,302) 2,706,523 Agency mortgage-backed securities 2,771,589 2,096 (123,872) 2,649,813 Non-agency mortgage-backed securities 122,373 — (4,343) 118,030 Corporate and university bonds 248,518 76 (31,007) 217,587 Total fixed maturity securities 16,457,723 24,240 (736,424) 15,745,539 Short-term investments 2,530,941 548 (6,579) 2,524,910 Investments, available-for-sale $ 18,988,664 $ 24,788 $ (743,003) $ 18,270,449 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, agencies and supranationals 2,554,874 34,352 (142,008) 2,447,218 Agency mortgage-backed securities 2,507,682 8,939 (135,611) 2,381,010 Non-agency mortgage-backed securities 355,673 — (22,603) 333,070 Corporate and university bonds 281,242 141 (26,781) 254,602 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	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. December 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 $ 1,593,711 $ (27,213) $ 1,444,869 $ (41,256) $ 3,038,580 $ (68,469) U.S. government-sponsored enterprises 415,333 (10,938) 691,781 (90,973) 1,107,114 (101,911) Obligations of states, municipalities and political subdivisions 1,133,275 (21,242) 2,024,298 (178,278) 3,157,573 (199,520) Foreign governments, agencies and supranationals 1,056,877 (29,890) 1,246,215 (177,412) 2,303,092 (207,302) Agency mortgage-backed securities 757,562 (13,880) 1,710,436 (109,992) 2,467,998 (123,872) Non-agency mortgage-backed securities — — 118,030 (4,343) 118,030 (4,343) Corporate and university bonds 2,107 (137) 212,404 (30,870) 214,511 (31,007) Total fixed maturity securities 4,958,865 (103,300) 7,448,033 (633,124) 12,406,898 (736,424) Short-term investments 163,503 (6,579) — — 163,503 (6,579) Total $ 5,122,368 $ (109,879) $ 7,448,033 $ (633,124) $ 12,570,401 $ (743,003) 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, agencies and supranationals 83,396 (394) 1,492,912 (141,614) 1,576,308 (142,008) Agency mortgage-backed securities 189,977 (1,872) 1,889,272 (133,739) 2,079,249 (135,611) Non-agency mortgage-backed securities — — 333,070 (22,603) 333,070 (22,603) Corporate and university bonds — — 236,205 (26,781) 236,205 (26,781) 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 Maturities By Contractual Maturity	c) The amortized cost and estimated fair value of fixed maturity securities at December 31, 2024 are shown below by contractual maturity. (dollars in thousands) Amortized Estimated Due in one year or less $ 1,593,149 $ 1,571,022 Due after one year through five years 6,071,013 5,901,682 Due after five years through ten years 4,647,538 4,406,225 Due after ten years 1,252,061 1,098,767 13,563,761 12,977,696 Mortgage-backed securities 2,893,962 2,767,843 Total fixed maturity securities $ 16,457,723 $ 15,745,539
Components Of Net Investment Income	d) The following table presents the components of net investment income. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Interest: Fixed maturity securities $ 510,044 $ 383,022 $ 294,417 Short-term investments 124,575 106,747 33,493 Cash and cash equivalents and restricted cash and cash equivalents 161,488 145,074 28,890 Dividends on equity securities 142,367 116,911 107,213 938,474 751,754 464,013 Investment expenses (17,978) (17,222) (17,258) Net investment income $ 920,496 $ 734,532 $ 446,755
Summary Of Net Realized Investment Gains (Losses) And The Change In Net Unrealized Gains On Investments	e) The following table presents the components of net investment gains (losses) included in net income (loss) and the pre-tax 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. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Fixed maturity securities, short-term investments and other investments: Net realized investment gains (losses) $ 4,423 $ (42,177) $ (40,983) Equity securities: Change in fair value of securities sold during the period (14,966) 34,684 (14,884) Change in fair value of securities held at the end of the period 1,817,762 1,531,547 (1,539,866) Total change in fair value 1,802,796 1,566,231 (1,554,750) Net investment gains (losses) $ 1,807,219 $ 1,524,054 $ (1,595,733) Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss): Fixed maturity securities $ (152,630) $ 389,498 $ (1,474,890) Short-term investments (12,793) 1,060 11,014 Net increase (decrease) $ (165,423) $ 390,558 $ (1,463,876)
Schedule of Restricted Assets	f) Total restricted assets are included on the Company's consolidated balance sheets as follows. December 31, (dollars in thousands) 2024 2023 Fixed maturity securities $ 3,027,863 $ 3,102,899 Equity securities 915,242 1,004,347 Short-term investments 704,201 807,138 Restricted cash and cash equivalents 499,581 584,974 Total $ 5,146,887 $ 5,499,358
Components Of Restricted Assets	The following table presents the components of restricted assets. December 31, (dollars in thousands) 2024 2023 Assets held in trust or on deposit to support underwriting activities $ 4,727,799 $ 5,048,857 Assets pledged as security for letters of credit 419,088 450,501 Total $ 5,146,887 $ 5,499,358

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 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. December 31, 2024 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments: Fixed maturity securities, available-for-sale: U.S. Treasury securities $ — $ 5,087,858 $ — $ 5,087,858 U.S. government-sponsored enterprises — 1,346,236 — 1,346,236 Obligations of states, municipalities and political subdivisions — 3,619,492 — 3,619,492 Foreign governments, agencies, and supranationals — 2,706,523 — 2,706,523 Agency mortgage-backed securities — 2,649,813 — 2,649,813 Non-agency mortgage-backed securities — 118,030 — 118,030 Corporate and university bonds — 217,587 — 217,587 Total fixed maturity securities, available-for-sale — 15,745,539 — 15,745,539 Equity securities: Insurance, banks and other financial institutions 4,968,736 — 1,384 4,970,120 Industrial, consumer and all other 6,814,401 — — 6,814,401 Total equity securities 11,783,137 — 1,384 11,784,521 Short-term investments, available-for-sale 2,363,736 161,174 — 2,524,910 Total investments $ 14,146,873 $ 15,906,713 $ 1,384 $ 30,054,970 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, agencies, and supranationals — 2,447,218 — 2,447,218 Agency mortgage-backed securities — 2,381,010 — 2,381,010 Non-agency mortgage-backed securities — 333,070 — 333,070 Corporate and university bonds — 254,602 — 254,602 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

Receivables (Tables)

Receivables (Tables)	12 Months Ended
	Dec. 31, 2024
Receivables [Abstract]
Components Of Receivables	The following table presents the components of receivables. December 31, (dollars in thousands) 2024 2023 Insurance Amounts receivable from agents, brokers and insureds $ 2,870,719 $ 2,686,199 Other insurance receivables 124,258 117,436 Markel Ventures 638,480 657,156 Other 26,651 25,604 3,660,108 3,486,395 Allowance for credit losses (33,309) (31,089) Receivables $ 3,626,799 $ 3,455,306

Goodwill And Intangible Assets

Goodwill And Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Rollforward of Components Of Goodwill	The following table presents a rollforward of the components of goodwill by reportable segment. (dollars in thousands) Insurance Reinsurance Markel Ventures Other insurance operations (1) Total January 1, 2023 $ 771,628 $ 122,745 $ 1,153,909 $ 590,556 $ 2,638,838 Adjustments to preliminary purchase price allocation — — (16,752) — (16,752) Foreign currency movements and other adjustments 1,195 — 497 971 2,663 December 31, 2023 (2) $ 772,823 $ 122,745 $ 1,137,654 $ 591,527 $ 2,624,749 Acquisitions (note 3) — — 114,589 — 114,589 Foreign currency movements and other adjustments (3,247) — (434) 210 (3,471) December 31, 2024 (2) $ 769,576 $ 122,745 $ 1,251,809 $ 591,737 $ 2,735,867 (1) Amounts included in other insurance operations reflect the Company's operations that are not included in a reportable segment and are primarily related to the Company's program services and insurance-linked securities operations. (2)
Rollforward of Components of Net Intangible Assets	The following table presents a rollforward of net intangible assets by reportable segment. (dollars in thousands) Underwriting (1) Markel Ventures Other insurance operations (2) Total January 1, 2023 $ 362,322 $ 796,297 $ 588,845 $ 1,747,464 Dispositions — — (2,000) (2,000) Amortization of acquired intangible assets (37,076) (82,370) (61,168) (180,614) Adjustments to preliminary purchase price allocation — 22,671 — 22,671 Foreign currency movements and other adjustments 98 119 946 1,163 December 31, 2023 $ 325,344 $ 736,717 $ 526,623 $ 1,588,684 Acquisitions (note 3) — 52,909 — 52,909 Amortization of acquired intangible assets (37,276) (81,317) (62,879) (181,472) Foreign currency movements and other adjustments (117) 154 (538) (501) December 31, 2024 $ 287,951 $ 708,463 $ 463,206 $ 1,459,620 (1) Amounts included in Underwriting reflect the intangible assets associated with the Company's underwriting segments, which are not allocated between the Insurance and Reinsurance segments. (2) Amounts included in other insurance operations reflect the Company's operations that are not included in a reportable segment and are primarily related to the Company's program services and insurance-linked securities operations.
Components of Intangible Assets	The following table presents the components of intangible assets. December 31, 2024 2023 (dollars in thousands) Gross Accumulated Gross Accumulated Customer relationships $ 1,488,796 $ (699,550) $ 1,450,503 $ (600,724) Investment management agreements 464,000 (178,727) 464,000 (149,560) Broker and agent relationships 295,694 (182,139) 297,693 (168,586) Trade names 305,381 (157,494) 293,270 (138,040) Technology 113,187 (107,727) 113,248 (100,781) Insurance licenses 72,333 — 72,333 — Other 159,603 (113,737) 169,681 (114,353) Total $ 2,898,994 $ (1,439,374) $ 2,860,728 $ (1,272,044)

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2024
Leases [Abstract]
Schedule Of Supplemental Balance Sheet Information Related to Leases	The following table summarizes details for the Company's operating leases recorded on the consolidated balance sheets. December 31, (dollars in thousands) 2024 2023 Right-of-use lease assets $ 681,405 $ 628,833 Lease liabilities $ 723,924 $ 657,217 Weighted average remaining lease term 9.0 years 9.8 years Weighted average discount rate 4.3 % 5.2 %
Maturities of Operating Lease Liabilities	The following table summarizes maturities of the Company's operating lease liabilities as of December 31, 2024, which reconciles to total operating lease liabilities included in other liabilities on the Company's consolidated balance sheet. Years Ending December 31, (dollars in thousands) 2025 $ 130,943 2026 116,324 2027 100,927 2028 88,473 2029 77,206 2030 and thereafter 368,468 Total lease payments 882,341 Less imputed interest (158,417) Total operating lease liabilities $ 723,924

Products, Services and Other _2

Products, Services and Other Revenues (Tables)	12 Months Ended
	Dec. 31, 2024
Revenue from Contract with Customer [Abstract]
Schedule Of Revenues From Contracts With Customers By Type	The following table presents revenues from contracts with customers by type, all of which are included in products revenues and services and other revenues in the consolidated statements of income (loss) and comprehensive income (loss), along with a reconciliation to total products revenues and services and other revenues. Years Ended December 31, 2024 2023 2022 (dollars in thousands) Markel Ventures Other Total Markel Ventures Other Total Markel Ventures Other Total Products $ 2,607,581 $ — $ 2,607,581 $ 2,487,054 $ — $ 2,487,054 $ 2,379,399 $ — $ 2,379,399 Services 2,315,822 10,193 2,326,015 2,262,861 10,341 2,273,202 2,184,196 43,875 2,228,071 Management fees — 97,226 97,226 — 99,509 99,509 — 79,209 79,209 Total revenues from contracts with customers 4,923,403 107,419 5,030,822 4,749,915 109,850 4,859,765 4,563,595 123,084 4,686,679 Leasing revenues 176,293 — 176,293 188,904 — 188,904 157,552 — 157,552 Fronting fees — 187,480 187,480 — 154,838 154,838 — 147,612 147,612 Equity method and other investments income (loss) 6,577 52,253 58,830 (1,744) (11,854) (13,598) 2,541 (17,661) (15,120) Disposition gains — — — — 16,923 16,923 — 225,828 225,828 Other 6,805 406 7,211 42,693 40 42,733 32,930 1,040 33,970 Total $ 5,113,078 $ 347,558 $ 5,460,636 $ 4,979,768 $ 269,797 $ 5,249,565 $ 4,756,618 $ 479,903 $ 5,236,521

Unpaid Losses And Loss Adjust_2

Unpaid Losses And Loss Adjustment Expenses (Tables)	12 Months Ended
	Dec. 31, 2024
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Reconciliation Of Consolidated Reserves For Losses And Loss Adjustment Expenses	a) The following table presents a reconciliation of consolidated beginning and ending reserves for losses and loss adjustment expenses. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Gross reserves for losses and loss adjustment expenses, beginning of year $ 23,483,321 $ 20,947,898 $ 18,178,894 Reinsurance recoverables on unpaid losses, beginning of year 8,820,567 7,994,884 6,876,317 Net reserves for losses and loss adjustment expenses, beginning of year 14,662,754 12,953,014 11,302,577 Effect of foreign currency rate changes on beginning of year balance (78,702) 70,344 (160,622) Adjusted net reserves for losses and loss adjustment expenses, beginning of year 14,584,052 13,023,358 11,141,955 Incurred losses and loss adjustment expenses: Current accident year 5,508,059 5,360,559 4,613,035 Prior accident years (455,310) (38,550) (167,446) Total incurred losses and loss adjustment expenses 5,052,749 5,322,009 4,445,589 Payments: Current accident year 720,178 729,895 580,537 Prior accident years 3,239,999 2,663,165 2,396,446 Total payments 3,960,177 3,393,060 2,976,983 Effect of foreign currency rate changes on current year activity (3,934) (1,532) (5,468) Change in net reserves for losses and loss adjustment expenses of Markel CATCo Re (see note 17) (159,963) (162,954) 347,921 Reinsurance recoverable on retroactive reinsurance transactions — (125,067) — Net reserves for losses and loss adjustment expenses, end of year 15,512,727 14,662,754 12,953,014 Reinsurance recoverables on unpaid losses, end of year 11,120,367 8,820,567 7,994,884 Gross reserves for losses and loss adjustment expenses, end of year $ 26,633,094 $ 23,483,321 $ 20,947,898
Prior Year Losses and Loss Adjustment Expenses Development by Segment and by Product Line	The following tables summarize, by segment, the product lines with the most significant changes in prior accident years loss reserves for the years ended December 31, 2024, 2023 and 2022, along with the corresponding accident years and the trends and factors that impacted management's best estimate of ultimate losses and loss adjustment expenses on underlying products in each of these product lines. The Company does not estimate losses at this level of aggregation as it offers a diverse portfolio of products and manages these products in more disaggregated groupings within each underwriting segment. As a result of the trends and factors described in the following tables, the Company's actuaries adjusted their estimates of the ultimate liability for unpaid losses and loss adjustment expenses. For those product lines with favorable development on prior accident years loss reserves, management has now given greater credibility to the favorable trends observed by the Company's actuaries and, upon incorporating these favorable trends into its best estimate, reduced prior years loss reserves accordingly. In 2023 and 2022, the unfavorable claims and loss trends experienced on the Company's U.S. general liability and professional liability product lines disrupted the development of the claims trend observed prior to 2022, reflecting broader market conditions, including the effects of economic and social inflation. In 2024, the Company's U.S. professional liability product lines continued to experience many of these same trends, while the U.S. general liability product lines began to stabilize, resulting in modest favorable development as management gave more credibility to the favorable trends observed by the Company's actuaries. Consistent with the Company's reserving philosophy, management is responding quickly to increase loss reserves following any indication of increased claims frequency or severity in excess of previous expectations, however in instances where trends have been more favorable than previously anticipated, management will wait to reduce loss reserves until those trends are observed over additional periods of time. Year Ended December 31, 2024 (dollars in millions) Loss Development Accident Years with Most Significant Development Trends and Factors Impacting Loss Estimates Insurance segment: Professional liability International $ (152.6) 2021 to 2023 Lower loss frequency and severity than previously anticipated, including on the cyber portfolio and middle market accounts U.S. 111.8 2017 to 2023 Unfavorable claims settlements and increased claim severity, primarily on the risk-managed directors and officers product line General liability (81.6) 2022 and 2023 More favorable loss experience within the U.S. business, as well as lower loss frequency and severity than previously anticipated on the international excess and umbrella product line Property (75.0) 2020 and 2023 Lower loss frequency and severity than previously anticipated across a number of subclasses in the U.S. and international portfolios Marine and energy (58.3) 2021 to 2023 More favorable loss experience than previously anticipated Programs (53.9) 2022 and 2023 Lower loss frequency and severity than previously anticipated on certain programs Credit and surety (51.4) 2021 to 2023 Lower loss frequency and severity than previously anticipated driven by the international trade credit product line Other products (90.0) Total Insurance (451.0) Reinsurance segment: Property (23.0) 2017 to 2020 Lower loss severity than previously anticipated and net favorable development on catastrophe events Workers' compensation (20.3) 2019, 2020 and 2023 Lower loss severity than previously anticipated and net favorable development on losses related to the COVID-19 pandemic Professional liability (17.1) 2021 to 2023 More favorable loss experience than previously anticipated Public entity 34.1 2017 to 2023 Increased frequency of large claims across the product line, which was discontinued in late 2024 Other products 18.0 Premium adjustments (4.0) Total Reinsurance (12.3) Other underwriting 8.0 Total decrease $ (455.3) Year Ended December 31, 2023 (dollars in millions) Loss Development Accident Years with Most Significant Development Trends and Factors Impacting Loss Estimates Insurance segment: General liability U.S. $ 274.0 2016 to 2021 Increased frequency of large claims and unfavorable loss cost trends, primarily on primary casualty contractors' liability and excess and umbrella product lines International (36.5) 2020 to 2022 Lower loss frequency and severity than previously anticipated Professional liability U.S. 56.8 Several Increased frequency of large claims and unfavorable loss cost trends, primarily on risk-managed errors and omissions product line International (102.2) 2020 Lower loss frequency and severity than previously anticipated Property (95.1) 2020 to 2022 Lower loss severity than previously anticipated and net favorable development on catastrophe events Marine and energy (76.5) 2021 and 2022 Lower loss severity than previously anticipated Personal lines (42.8) 2022 Lower loss frequency and severity than previously anticipated Workers' compensation (36.5) 2021 and 2022 Lower loss severity than previously anticipated Other products (45.9) Total Insurance (104.7) Reinsurance segment: General liability 95.5 2015 to 2021 Large reported claims and adverse loss development trends Public entity 53.7 2014 to 2019 Increased frequency of large claims on a segment of business that was discontinued in 2020 Premium adjustments 11.4 2021 and 2022 Recognition of additional exposures on prior accident years related to net favorable premium adjustments primarily on general liability, partially offset by reduced exposures recognized primarily on professional liability Property (21.6) 2017 to 2019 More favorable loss experience and lower loss severity than previously anticipated Workers' compensation (14.9) Several Lower loss frequency and severity than previously anticipated Other products (67.0) Total Reinsurance 57.1 Other underwriting 9.0 Total decrease $ (38.6) Year Ended December 31, 2022 (dollars in millions) Loss Development Accident Years with Most Significant Development Trends and Factors Impacting Loss Estimates Insurance segment: Professional liability 2018 and 2019 accident years $ 121.0 2018 and 2019 Unfavorable claims settlements and increased claim frequency and severity, primarily on directors and officers, errors and omissions and employment practices liability lines All other accident years (91.1) Several More favorable loss experience and lower loss severity than previously anticipated General liability 2016 to 2019 accident years 61.6 2016 to 2019 Unfavorable claims settlements and increased claim frequency and severity, primarily on contractors and excess and umbrella lines All other accident years (20.5) Several Lower loss frequency and severity than previously anticipated Workers' compensation (62.1) 2016 to 2021 Lower loss severity than previously anticipated Programs (48.3) 2020 and 2021 Lower than expected frequency of claims Property (48.1) 2020 and 2021 Lower loss severity than originally anticipated as well as favorable development on losses related to the COVID-19 pandemic Credit and surety (31.7) 2019 to 2021 Lower than expected frequency of claims Other products (23.7) Total Insurance (142.9) Reinsurance segment: Property (29.2) 2017 to 2019 Favorable development on catastrophe events Credit and surety (22.9) Several Favorable commutations on mortgage insurance contracts Premium adjustments 53.1 2020 and 2021 Recognition of additional exposures on prior accident years related to net favorable premium adjustments primarily on general liability, credit and surety and professional liability Other products (27.1) Total Reinsurance (26.1) Other 1.6 Total decrease $ (167.4)
Ultimate Incurred Losses And Cumulative Paid Losses And Allocated Loss Adjustment Expenses, Net Of Reinsurance	The Insurance segment table that follows also includes claim count information, by accident year. The Company defines a claim as a single claim incident, per policy, which may include multiple claimants and multiple coverages on a single policy. Claim counts include claims closed without a payment as well as claims where the Company is monitoring to determine if an exposure exists, even if a reserve has not been established. All of the business contained within the Company's Reinsurance segment represents treaty business that is assumed from other insurance or reinsurance companies, for which the Company does not have access to the underlying claim counts. Further, this business includes both quota share and excess of loss treaty reinsurance, through which only a portion of each reported claim results in losses to the Company. As such, the Company has excluded claim count information from the Reinsurance segment disclosures. Insurance Segment (dollars in millions) Ultimate Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance Total of Incurred-but-Not-Reported Liabilities, Net of Reinsurance Cumulative Number of Reported Claims Unaudited As of December 31, As of December 31, Accident Year 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 December 31, 2024 2015 $ 1,767.5 $ 1,693.8 $ 1,571.0 $ 1,517.0 $ 1,486.5 $ 1,454.7 $ 1,450.6 $ 1,440.9 $ 1,460.0 $ 1,457.1 $ 58.0 88,000 2016 1,856.3 1,852.8 1,753.6 1,700.3 1,674.7 1,667.4 1,678.4 1,732.9 1,718.1 77.2 100,000 2017 2,309.0 2,176.7 2,059.3 1,998.7 2,004.5 2,023.9 2,111.2 2,152.3 124.6 140,000 2018 2,429.0 2,320.8 2,199.2 2,058.8 2,151.2 2,331.6 2,417.1 177.8 193,000 2019 2,552.4 2,402.2 2,239.7 2,293.7 2,471.7 2,526.8 206.9 228,000 2020 3,185.1 2,972.1 2,914.2 2,858.5 2,771.6 434.3 183,000 2021 3,083.5 2,907.1 2,755.4 2,720.1 531.0 149,000 2022 3,746.8 3,365.5 3,342.6 1,098.3 159,000 2023 4,435.9 3,901.7 1,802.5 169,000 2024 4,532.5 3,271.7 149,000 Total $ 27,539.9 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance Unaudited As of December 31, As of December 31, Accident Year 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2015 $ 320.7 $ 660.0 $ 870.2 $ 1,032.9 $ 1,141.3 $ 1,208.4 $ 1,259.2 $ 1,291.7 $ 1,327.3 $ 1,344.7 2016 369.8 746.2 973.7 1,158.2 1,262.8 1,350.3 1,425.5 1,479.6 1,529.8 2017 434.9 982.7 1,274.3 1,462.0 1,619.2 1,739.8 1,839.6 1,909.5 2018 490.7 1,017.4 1,281.9 1,494.9 1,671.6 1,856.5 2,017.4 2019 524.1 991.1 1,262.9 1,576.4 1,910.9 2,104.4 2020 568.1 1,148.5 1,515.7 1,772.5 2,033.8 2021 473.4 985.8 1,357.5 1,751.1 2022 484.5 1,059.9 1,564.1 2023 596.9 1,396.6 2024 651.3 Total $ 16,302.7 All outstanding liabilities for unpaid losses and loss adjustment expenses before 2014, net of reinsurance 313.3 Total liabilities for unpaid losses and loss adjustment expenses, net of reinsurance $ 11,550.5 Reinsurance Segment Ultimate Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance Total of Incurred-but-Not-Reported Liabilities, Net of Reinsurance Unaudited As of December 31, (dollars in millions) As of December 31, Accident Year 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 December 31, 2024 2015 $ 523.0 $ 508.8 $ 524.6 $ 516.0 $ 504.8 $ 499.9 $ 487.8 $ 488.2 $ 500.0 $ 477.7 $ 56.6 2016 506.6 515.2 515.4 513.4 523.4 548.1 551.5 573.3 556.5 30.1 2017 894.4 927.6 933.2 934.9 907.3 919.7 931.0 931.3 44.2 2018 743.0 764.9 757.4 762.5 758.1 821.0 790.1 82.2 2019 654.4 668.4 683.1 691.0 719.0 730.4 129.1 2020 678.1 730.5 741.0 762.8 765.2 230.1 2021 731.9 733.6 754.7 753.9 303.8 2022 661.1 601.9 616.4 413.4 2023 658.3 665.3 506.7 2024 730.3 674.3 Total $ 7,017.1 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance Unaudited As of December 31, As of December 31, Accident Year 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2015 $ 63.3 $ 130.3 $ 201.0 $ 251.6 $ 298.6 $ 323.2 $ 342.8 $ 359.5 $ 375.6 $ 388.6 2016 78.6 166.7 236.4 292.7 344.4 377.9 418.0 451.6 475.7 2017 157.1 357.5 478.6 560.4 623.8 692.8 747.6 796.0 2018 86.9 235.1 334.9 404.4 474.4 543.6 613.9 2019 53.2 169.1 261.3 351.8 435.6 507.7 2020 93.2 202.9 308.7 381.8 463.0 2021 79.2 187.1 281.6 361.0 2022 24.1 66.6 138.4 2023 27.1 79.5 2024 23.9 Total $ 3,847.7 All outstanding liabilities for unpaid losses and loss adjustment expenses before 2014, net of reinsurance 273.3 Total liabilities for unpaid losses and loss adjustment expenses, net of reinsurance $ 3,442.7
Average Annual Percentage Payout Of Incurred Losses By Age (in Years), Net Of Reinsurance	The following table presents supplementary information about average historical claims duration as of December 31, 2024 based on the cumulative incurred and paid losses and allocated loss adjustment expenses presented above. Average Annual Percentage Payout of Incurred Losses by Age (in Years), Net of Reinsurance Unaudited 1 2 3 4 5 6 7 8 9 10 Insurance 18.7 % 20.9 % 13.1 % 10.8 % 8.5 % 6.1 % 4.8 % 2.9 % 2.7 % 1.2 % Reinsurance 9.6 % 14.4 % 12.9 % 10.1 % 9.5 % 7.4 % 6.5 % 4.9 % 3.8 % 2.7 %
Reconciliation Of Net Incurred And Paid Loss Development Tables, By Segment, To The Liability For Losses And Loss Adjustment Expenses In The Consolidated Balance Sheet	The following table reconciles the net incurred and paid loss development tables to the liability for losses and loss adjustment expenses on the consolidated balance sheet. (dollars in thousands) December 31, 2024 Net outstanding liabilities Insurance segment $ 11,550,516 Reinsurance segment 3,442,663 Other underwriting 62,903 Program services and ILS fronting 6,615 Markel CATCo Re (see note 17) 25,005 Liabilities for unpaid losses and loss adjustment expenses, net of reinsurance 15,087,702 Reinsurance recoverable on unpaid losses Insurance segment 4,129,856 Reinsurance segment 397,810 Other underwriting 84,079 Program services and ILS fronting 6,508,622 Total reinsurance recoverable on unpaid losses 11,120,367 Unallocated loss adjustment expenses 425,025 Total gross liability for unpaid losses and loss adjustment expenses $ 26,633,094

Reinsurance (Tables)

Reinsurance (Tables)	12 Months Ended
	Dec. 31, 2024
Reinsurance Disclosures [Abstract]
Effect Of Reinsurance And Retrocessional Reinsurance On Consolidated Premiums Written And Earned	The following tables summarize the effect of reinsurance and retrocessional reinsurance on premiums written and earned. Year Ended December 31, 2024 (dollars in thousands) Direct Assumed Ceded Net Premiums Underwriting: Written $ 8,860,015 $ 1,691,858 $ (2,252,122) $ 8,299,751 Earned $ 8,801,477 $ 1,628,408 $ (1,993,895) $ 8,435,990 Fronting: Written 3,234,025 1,708,733 (4,946,334) (3,576) Earned 3,053,947 1,559,599 (4,617,124) (3,578) Consolidated: Written $ 12,094,040 $ 3,400,591 $ (7,198,456) $ 8,296,175 Earned $ 11,855,424 $ 3,188,007 $ (6,611,019) $ 8,432,412 Year Ended December 31, 2023 (dollars in thousands) Direct Assumed Ceded Net Premiums Underwriting: Written $ 8,657,266 $ 1,620,366 $ (1,878,844) $ 8,398,788 Earned $ 8,363,710 $ 1,616,630 $ (1,683,648) $ 8,296,692 Fronting: Written 2,649,217 1,075,388 (3,725,818) (1,213) Earned 2,636,179 937,400 (3,574,792) (1,213) Consolidated: Written $ 11,306,483 $ 2,695,754 $ (5,604,662) $ 8,397,575 Earned $ 10,999,889 $ 2,554,030 $ (5,258,440) $ 8,295,479 Year Ended December 31, 2022 (dollars in thousands) Direct Assumed Ceded Net Premiums Underwriting: Written $ 8,085,812 $ 1,761,726 $ (1,640,165) $ 8,207,373 Earned $ 7,379,766 $ 1,589,920 $ (1,378,191) $ 7,591,495 Fronting: Written 2,644,138 710,006 (3,358,127) (3,983) Earned 2,688,804 656,885 (3,349,392) (3,703) Consolidated: Written $ 10,729,950 $ 2,471,732 $ (4,998,292) $ 8,203,390 Earned $ 10,068,570 $ 2,246,805 $ (4,727,583) $ 7,587,792
Effect of Reinsurance And Retrocessional Reinsurance on Incurred 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. Years ended December 31, (dollars in thousands) 2024 2023 2022 Gross losses and loss adjustment expenses $ 6,970,871 $ 6,817,630 $ 5,281,424 Ceded losses and loss adjustment expenses (1,917,318) (1,496,265) (834,648) Net losses and loss adjustment expenses $ 5,053,553 $ 5,321,365 $ 4,446,776

Life And Annuity Benefits (Tabl

Life And Annuity Benefits (Tables)	12 Months Ended
	Dec. 31, 2024
Schedule of Future Policyholder Benefits, Life and Annuity	The following table presents the components of the Company's liabilities for life and annuity benefits. December 31, (dollars in thousands) 2024 2023 Liability for future policyholder benefits $ 491,370 $ 557,763 Deferred profit liability 51,482 52,287 Other 40,421 39,004 Total $ 583,273 $ 649,054
Liability for Future Policy Benefit, Activity	The following table presents a rollforward of the present value of the liability for future policyholder benefits. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Liability for future policyholder benefits, beginning of year $ 557,763 $ 554,366 $ 821,632 Liability for future policyholder benefits at original discount rate, beginning of year 642,877 667,761 745,313 Effect of changes in cash flow assumptions — — — Effect of actual variances from expected experience (4,745) (5,890) (3,859) Adjusted liability for future policyholder benefits, beginning of year 638,132 661,871 741,454 Interest accretion 13,996 14,889 15,625 Benefit payments (49,200) (52,588) (53,232) Effect of foreign currency rate changes (26,126) 18,705 (36,086) Liability for future policyholder benefits at original discount rate, end of year 576,802 642,877 667,761 Cumulative effect of changes in discount rate assumptions (85,432) (85,114) (113,395) Liability for future policyholder benefits, end of year $ 491,370 $ 557,763 $ 554,366 Liability for future policyholder benefits, undiscounted, end of year $ 737,575 $ 824,642 $ 861,264
Schedule of Additional Details of Liability for Future Policyholder Benefits, Life and Annuity	The following table summarizes additional details for the Company's liability for future policyholder benefits. December 31, 2024 2023 Weighted-average interest rate: Interest accretion rate 2.3 % 2.3 % Current discount rate 4.0 % 3.8 % Weighted-average liability duration 8.3 years 8.6 years

Senior Long-Term Debt And Oth_2

Senior Long-Term Debt And Other Debt (Tables)	12 Months Ended
	Dec. 31, 2024
Debt Disclosure [Abstract]
Summary Of Senior Long-Term Debt And Other Debt	The following table summarizes the Company's senior long-term debt and other debt. December 31, (dollars in thousands) 2024 2023 3.50% unsecured senior notes, due November 1, 2027, interest payable semi-annually, net of unamortized discount of $592 in 2024 and $876 in 2023 $ 299,236 $ 298,869 3.35% unsecured senior notes, due September 17, 2029, interest payable semi-annually, net of unamortized discount of $1,174 in 2024 and $1,421 in 2023 298,590 298,294 7.35% unsecured senior notes, due August 15, 2034, interest payable semi-annually, net of unamortized discount of $663 in 2024 and $731 in 2023 129,148 129,076 5.0% unsecured senior notes, due March 30, 2043, interest payable semi-annually, net of unamortized discount of $4,087 in 2024 and $4,311 in 2023 245,687 245,451 5.0% unsecured senior notes, due April 5, 2046, interest payable semi-annually, net of unamortized discount of $5,202 in 2024 and $5,445 in 2023 494,135 493,860 4.30% unsecured senior notes, due November 1, 2047, interest payable semi-annually, net of unamortized discount of $3,364 in 2024 and $3,516 in 2023 296,049 295,870 5.0% unsecured senior notes, due May 20, 2049, interest payable semi-annually, net of unamortized discount of $6,378 in 2024 and $6,639 in 2023 592,538 592,233 4.15% unsecured senior notes, due September 17, 2050, interest payable semi-annually, net of unamortized discount of $4,563 in 2024 and $4,740 in 2023 494,749 494,546 3.45% unsecured senior notes, due May 7, 2052, interest payable semi-annually, net of unamortized discount of $7,626 in 2024 and $7,904 in 2023 591,316 591,000 6.00% unsecured senior notes, due May 16, 2054, interest payable semi-annually, net of unamortized discount of $7,240 in 2024 and $0 in 2023 591,511 — Other debt, with a weighted average interest rate of 5.4% in 2024 and 5.0% in 2023 297,382 340,597 Senior long-term debt and other debt $ 4,330,341 $ 3,779,796
Summary Of Future Principal Payments Due At Maturity On Senior Long-Term Debt And Other Debt	The following table summarizes the future principal payments on senior long-term debt and other debt as of December 31, 2024. (dollars in thousands) Senior long-term debt Other debt Total Years Ending December 31, 2025 $ — $ 41,843 $ 41,843 2026 — 41,902 41,902 2027 300,000 158,376 458,376 2028 — 16,724 16,724 2029 300,000 15,182 315,182 2030 and thereafter 3,479,846 25,905 3,505,751 Total principal payments 4,079,846 299,932 4,379,778 Net unamortized discount (40,889) — (40,889) Net unamortized debt issuance costs (5,998) (2,550) (8,548) Total $ 4,032,959 $ 297,382 $ 4,330,341

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Components Of Income Before Income Taxes	Income (loss) before income taxes includes the following components, based on country of domicile. Years Ended December 31, (dollars in thousands) 2024 2023 2022 U.S. operations $ 2,428,694 $ 1,711,849 $ (109,311) Foreign operations 1,209,006 941,857 (42,255) Income (loss) before income taxes $ 3,637,700 $ 2,653,706 $ (151,566)
Components Of Income Tax Expense (Benefit)	Income tax expense (benefit) includes the following components, based on the taxing authority to which taxes are paid. The Company's most significant U.K. and Bermuda subsidiaries have elected to be taxed as domestic corporations for U.S. tax purposes. U.S. income taxes have not been recognized on any undistributed earnings of the Company's foreign subsidiaries that are considered indefinitely reinvested, the amount of which is not material to the consolidated financial statements. U.S. income tax includes applicable state income tax expense. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Current: U.S. income tax $ 271,801 $ 249,149 $ 222,074 Foreign income tax 123,933 69,669 12,042 Total current tax expense 395,734 318,818 234,116 Deferred: U.S. income tax 399,169 250,041 (301,423) Foreign income tax (4,609) (16,243) 19,098 Total deferred tax expense (benefit) 394,560 233,798 (282,325) Income tax expense (benefit) $ 790,294 $ 552,616 $ (48,209)
Reconciliations Of United States Corporate Income Tax Rate To Effective Tax Rate On Income Before Income Taxes	The following table presents a reconciliation of the Company's income taxes using the U.S. corporate income tax rate to the Company's income tax expense (benefit). Years Ended December 31, (dollars in thousands) 2024 2023 2022 U.S. corporate tax rate $ 763,917 21.0 % $ 557,278 21.0 % $ (31,829) 21.0 % Increase (decrease) resulting from: State income taxes, net of U.S. federal income tax benefit 39,770 1.1 27,007 1.0 3,369 (2.2) Tax-exempt investment income (14,830) (0.4) (15,328) (0.6) (16,063) 10.6 Foreign operations 12,985 0.3 10,854 0.4 5,335 (3.5) Impairment of goodwill — — — — 16,800 (11.1) Markel CATCo Re income not subject to tax (12,201) (0.3) (15,013) (0.6) (18,871) 12.5 Other 653 0.0 (12,182) (0.4) (6,950) 4.5 Income tax expense (benefit) $ 790,294 21.7 % $ 552,616 20.8 % $ (48,209) 31.8 %
Components Of Domestic And Foreign Deferred Tax Assets And Liabilities	The following table presents the components of domestic and foreign deferred tax assets and liabilities. December 31, (dollars in thousands) 2024 2023 Assets: Unpaid losses and loss adjustment expenses $ 233,583 $ 216,863 Lease liabilities 172,131 161,350 Unearned premiums 164,485 168,172 Accrued incentive compensation 51,943 52,853 Tax credit carryforwards 45,481 25,396 Net operating loss carryforwards 37,168 43,439 Life and annuity benefits 29,143 39,729 Other differences between financial reporting and tax bases 106,667 93,693 Total gross deferred tax assets 840,601 801,495 Less valuation allowance (33,292) (13,916) Total gross deferred tax assets, net of allowance 807,309 787,579 Liabilities: Investments 1,566,540 1,196,717 Deferred policy acquisition costs 173,742 176,382 Goodwill and other intangible assets 170,941 175,767 Right-of-use lease assets 162,628 152,939 Property, plant and equipment 160,615 152,149 Other differences between financial reporting and tax bases 113,873 104,024 Total gross deferred tax liabilities 2,348,339 1,957,978 Net deferred tax liability $ 1,541,030 $ 1,170,399

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Amounts attributable to Markel CATCo Re in Markel Group's consolidated balance sheet	The Company's consolidated balance sheets include the following amounts attributable to MCRe. December 31, ( dollars in thousands ) 2024 2023 Assets Cash and cash equivalents $ 34,497 $ 91,301 Restricted cash and cash equivalents 28,701 173,800 Other assets and receivables due from cedents 329 19,292 Total Assets $ 63,527 $ 284,393 Liabilities and Equity Unpaid losses and loss adjustment expenses $ 25,005 $ 184,967 Other liabilities 66 1,842 Total Liabilities 25,071 186,809 Shareholders' equity 21,139 21,139 Noncontrolling interests 17,317 76,445 Total Equity 38,456 97,584 Total Liabilities and Equity $ 63,527 $ 284,393

Related Party Disclosures (Tabl

Related Party Disclosures (Tables)	12 Months Ended
	Dec. 31, 2024
Related Party Transactions [Abstract]
Hagerty Related Party [Table Text Block]	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. Years Ended December 31, (dollars in thousands) 2024 2023 2022 Gross written premiums attributable to Hagerty $ 922,657 $ 805,673 $ 689,670 Premiums ceded to Hagerty Re $ 708,147 $ 616,491 $ 456,637

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2024
Stockholders' Equity Note [Abstract]
Schedule of Common Stock Outstanding Roll Forward	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. Years Ended December 31, (in ones) 2024 2023 Issued and outstanding common shares, beginning of year 13,131,672 13,422,692 Issuance of common shares 28,479 30,740 Repurchase of common shares (370,034) (321,760) Issued and outstanding common shares, end of year 12,790,117 13,131,672
Schedule Of Net Income Per Common Share	c) The following table presents net income (loss) per common share and diluted net income (loss) per common share. Years Ended December 31, (in thousands, except per share amounts) 2024 2023 2022 Net income (loss) to common shareholders $ 2,711,022 $ 1,960,060 $ (252,277) Adjustment of redeemable noncontrolling interests (111,700) 6,212 (69,896) Adjusted net income (loss) to common shareholders $ 2,599,322 $ 1,966,272 $ (322,173) Weighted average basic common shares outstanding 13,017 13,347 13,580 Weighted average dilutive potential common shares from restricted stock units and restricted stock (1) (2) 24 31 — Weighted average diluted common shares outstanding 13,041 13,378 13,580 Basic net income (loss) per common share $ 199.69 $ 147.32 $ (23.72) Diluted net income (loss) per common share (1) (2) $ 199.32 $ 146.98 $ (23.72) (1) The Company has issued grants and awards of restricted stock units to employees as performance, retention or hiring incentives, as well as awards of restricted stock to non-employee directors, under its equity incentive compensation plan. At December 31, 2024, there were 284,049 shares available for future awards under the Company's equity incentive compensation plan. (2) The impact of 33 thousand shares from restricted stock units and restricted stock was excluded from the computation of diluted net loss per common share for the year ended December 31, 2022 because the effect would have been anti-dilutive.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2024
Other Comprehensive Income (Loss), Tax [Abstract]
Change In Accumulated Other Comprehensive Income By Component, Net Of Noncontrolling Interests	The following table presents the change in accumulated other comprehensive income (loss) by component, net of noncontrolling interests. (dollars in thousands) Net unrealized gains (losses) on available-for-sale investments Life and annuity discount rate assumption Foreign currency Net actuarial pension loss Accumulated other comprehensive income (loss) December 31, 2021 $ 388,554 $ (60,291) $ (56,631) $ (49,624) $ 222,008 Total other comprehensive income (loss) before income taxes (1,463,876) 189,714 (9,677) 31,222 (1,252,617) Income tax (expense) benefit 309,046 (39,840) 401 (6,492) 263,115 Total other comprehensive income (loss) (1,154,830) 149,874 (9,276) 24,730 (989,502) December 31, 2022 $ (766,276) $ 89,583 $ (65,907) $ (24,894) $ (767,494) Total other comprehensive income (loss) before income taxes 390,558 (28,281) 4,650 94 367,021 Income tax (expense) benefit (83,655) 5,938 — (20) (77,737) Total other comprehensive income (loss) 306,903 (22,343) 4,650 74 289,284 December 31, 2023 $ (459,373) $ 67,240 $ (61,257) $ (24,820) $ (478,210) Total other comprehensive income (loss) before income taxes (165,423) 319 (3,883) (6,600) (175,587) Income tax (expense) benefit 35,128 (67) — 1,654 36,715 Total other comprehensive income (loss) (130,295) 252 (3,883) (4,946) (138,872) December 31, 2024 $ (589,668) $ 67,492 $ (65,140) $ (29,766) $ (617,082)

Statutory Financial Informati_2

Statutory Financial Information (Tables)	12 Months Ended
	Dec. 31, 2024
Statutory Financial Information [Abstract]
Statutory Capital And Surplus	a) The following table summarizes statutory capital and surplus for the Company's insurance subsidiaries. December 31, (dollars in thousands) 2024 2023 United States $ 6,764,770 $ 5,958,801 United Kingdom $ 1,001,574 $ 977,604 Bermuda $ 2,414,364 $ 2,353,058 Germany $ 171,581 $ 166,403
Statutory Net Income (Loss)	The following table summarizes statutory net income (loss) for the Company's insurance subsidiaries. Years Ended December 31, (dollars in thousands) 2024 2023 2022 United States $ 500,860 $ 196,952 $ 689,341 United Kingdom $ 62,084 $ 116,436 $ 35,719 Bermuda $ 614,056 $ 484,417 $ (144,239) Germany $ 10,075 $ 5,543 $ (2,471)

Markel Group (Parent Company _2

Markel Group (Parent Company Only) Financial Information (Tables)	12 Months Ended
	Dec. 31, 2024
Condensed Financial Information Disclosure [Abstract]
Schedule Of Condensed Balance Sheets	CONDENSED BALANCE SHEETS December 31, 2024 2023 (dollars in thousands) ASSETS Investments, at estimated fair value: Fixed maturity securities, available-for-sale (amortized cost of $130,983 in 2024 and $139,766 in 2023) $ 123,053 $ 131,544 Equity securities (cost of $1,084,814 in 2024 and $1,089,332 in 2023) 2,071,110 1,731,839 Short-term investments, available-for-sale (estimated fair value approximates cost) 1,410,830 1,032,118 Total Investments 3,604,993 2,895,501 Cash and cash equivalents 701,289 635,047 Restricted cash and cash equivalents 20,013 15,908 Investments in consolidated subsidiaries 16,699,125 14,928,756 Other assets 450,327 441,977 Total Assets $ 21,475,747 $ 18,917,189 LIABILITIES AND SHAREHOLDERS' EQUITY Senior long-term debt $ 4,032,960 $ 3,439,197 Income taxes payable 179,381 213,770 Net deferred tax liability 274,661 201,140 Other liabilities 72,847 79,154 Total Liabilities 4,559,849 3,933,261 Shareholders' equity: Preferred stock 591,891 591,891 Common stock 3,560,633 3,517,146 Retained earnings 13,380,456 11,353,101 Accumulated other comprehensive loss (617,082) (478,210) Total Shareholders' Equity 16,915,898 14,983,928 Total Liabilities and Shareholders' Equity $ 21,475,747 $ 18,917,189
Schedule Of Condensed Statements Of Income (Loss) And Comprehensive Income (Loss)	CONDENSED STATEMENTS OF INCOME (LOSS) AND COMPREHENSIVE INCOME (LOSS) Years Ended December 31, 2024 2023 2022 (dollars in thousands) REVENUES Net investment income $ 86,583 $ 92,080 $ 34,781 Dividends on common stock of consolidated subsidiaries 575,008 310,000 278,557 Net investment gains (losses): Net realized investment gains (losses) 16,718 (515) 7,620 Change in fair value of equity securities 342,623 275,048 (397,906) Net investment gains (losses) 359,341 274,533 (390,286) Gain on sale of subsidiary — — 107,293 Other revenues (losses) 31,132 (28,718) (29,487) Total Revenues 1,052,064 647,895 858 EXPENSES Interest expense 179,626 156,953 172,125 Other expenses 12,061 19,716 111,848 Net foreign exchange losses (gains) (36,907) 9,038 (13,143) Total Expenses 154,780 185,707 270,830 Income (Loss) Before Equity in Undistributed Earnings (Losses) of Consolidated Subsidiaries and Income Taxes 897,284 462,188 (269,972) Equity in undistributed earnings (losses) of consolidated subsidiaries 1,941,339 1,580,347 (72,125) Income tax (expense) benefit (91,601) (46,475) 125,820 Net Income (Loss) to Shareholders 2,747,022 1,996,060 (216,277) Preferred stock dividends (36,000) (36,000) (36,000) Net Income (Loss) to Common Shareholders $ 2,711,022 $ 1,960,060 $ (252,277) OTHER COMPREHENSIVE INCOME (LOSS) TO SHAREHOLDERS Change in net unrealized gains (losses) on available-for-sale investments, net of taxes: Net holding gains (losses) arising during the period $ 109 $ 1,453 $ (24,465) Consolidated subsidiaries' net holding gains (losses) arising during the period (148,411) 276,910 (1,175,271) Reclassification adjustments for net gains (losses) included in net income (loss) to shareholders 365 (92) 1,965 Consolidated subsidiaries' reclassification adjustments for net losses included in net income (loss) to shareholders 17,642 28,632 42,941 Change in net unrealized gains (losses) on available-for-sale investments, net of taxes (130,295) 306,903 (1,154,830) Consolidated subsidiaries' change in discount rate for life and annuity benefits, net of taxes 252 (22,343) 149,874 Consolidated subsidiaries' change in foreign currency translation adjustments, net of taxes (3,883) 4,650 (9,276) Consolidated subsidiaries' change in net actuarial pension loss, net of taxes (4,946) 74 24,730 Total Other Comprehensive Income (Loss) to Shareholders (138,872) 289,284 (989,502) Comprehensive Income (Loss) to Shareholders $ 2,608,150 $ 2,285,344 $ (1,205,779)
Schedule Of Condensed Statements Of Cash Flows	CONDENSED STATEMENTS OF CASH FLOWS Years Ended December 31, 2024 2023 2022 (dollars in thousands) OPERATING ACTIVITIES Net income (loss) to shareholders $ 2,747,022 $ 1,996,060 $ (216,277) Adjustments to reconcile net income (loss) to shareholders to net cash provided by operating activities (2,183,635) (1,664,382) 489,413 Net Cash Provided By Operating Activities 563,387 331,678 273,136 INVESTING ACTIVITIES Proceeds from sales, maturities, calls and prepayments of fixed maturity securities 14,459 72,834 13,047 Cost of fixed maturity securities purchased (6,516) (48,501) — Proceeds from sales of equity securities 3,662 24,237 65,379 Cost of equity securities purchased (310) (7,731) (16,660) Net change in short-term investments (315,622) 451,846 58,970 Decrease (increase) in notes receivable due from subsidiaries — — 75,645 Capital contributions to subsidiaries (174,002) (55,575) (94,585) Proceeds from sale of subsidiary — 16,090 165,615 Cost of equity method investments — (5,000) — Other 2,694 (12,691) 4,779 Net Cash Provided (Used) By Investing Activities (475,635) 435,509 272,190 FINANCING ACTIVITIES Repayment of senior long-term debt — (250,000) (350,000) Additions to senior long-term debt 592,596 — — Decrease in notes payable to subsidiaries — — (32,753) Repurchases of common stock (572,728) (445,479) (290,796) Dividends paid on preferred stock (36,000) (36,000) (36,000) Other (1,273) — — Net Cash Used By Financing Activities (17,405) (731,479) (709,549) Increase (decrease) in cash, cash equivalents, restricted cash and restricted cash equivalents 70,347 35,708 (164,223) Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of year 650,955 615,247 779,470 CASH, CASH EQUIVALENTS, RESTRICTED CASH AND RESTRICTED CASH EQUIVALENTS AT END OF YEAR $ 721,302 $ 650,955 $ 615,247 SUPPLEMENTAL CASH FLOW INFORMATION Cash dividends received from subsidiaries $ 575,000 $ 310,000 $ 245,102 Non-cash capital contributions to subsidiaries $ — $ 43,111 $ 923,980

Summary Of Significant Accoun_3

Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Deferred policy acquisition cost amortization period	1 year
Property, plant and equipment, net	$ 1,400	$ 1,300
Inventory, net	$ 631.5	$ 617.2
Tax benefit greater than 50%	50%
Insurance premiums revenue recognition period	1 year

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Investments) (Details)	12 Months Ended
	Dec. 31, 2024
Minimum [Member] | Fixed maturities [Member]
Schedule of Investments [Line Items]
Investment maturity period	1 year
Maximum [Member] | Short-term investments [Member]
Schedule of Investments [Line Items]
Investment maturity period	1 year

Summary of Significant Accoun_5

Summary of Significant Accounting Policies (Cash and Cash Equivalents) (Details)	12 Months Ended
	Dec. 31, 2024
Maximum [Member]
Cash and Cash Equivalents [Line Items]
Investment maturity period, cash and cash equivalents	90 days

Summary of Significant Accoun_6

Summary of Significant Accounting Policies (Goodwill and Intangible Assets) (Details)	Dec. 31, 2024
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, estimated useful life	5 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, estimated useful life	20 years

Segment Reporting Disclosures_2

Segment Reporting Disclosures (Narrative) (Details) - segment	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Number of Reportable Segments	4
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]	Chief Executive Officer [Member]
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description	The chief operating decision maker uses segment operating income to assess the performance of each segment and determine how to allocate capital. The chief operating decision maker allocates capital where he believes it will earn an appropriate return.
Underwriting Operations [Member] | United States [Member]
Segment Reporting Information [Line Items]
Percentage of gross premiums written	75%	75%	75%
Markel Ventures [Member] | United States [Member]
Segment Reporting Information [Line Items]
Percentage of revenue attributable to U.S.	94%	95%	96%

Segment Reporting Disclosures_3

Segment Reporting Disclosures (Company's Segment Disclosures) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Earned premiums		$ 8,432,412	$ 8,295,479	$ 7,587,792
Net investment income		920,496	734,532	446,755
Net investment gains (losses)		1,807,219	1,524,054	(1,595,733)
Products revenues		2,635,659	2,545,053	2,427,096
Services and other revenues		2,824,977	2,704,512	2,809,425
Total operating revenues		16,620,763	15,803,630	11,675,335
Attritional Current Year Claims and Claims Adjustment Expense		5,437,410	5,320,487	4,531,098
Catastrophe Current Year Claims and Claims Adjustment Expense		70,649	40,072	81,937
Losses and loss adjustment expenses, prior accident years		455,310	38,550	167,446
Amortization of policy acquisition costs		(1,754,141)	(1,763,670)	(1,655,106)
Other underwriting expenses		(1,223,248)	(1,077,064)	(860,477)
Products expenses		(2,272,219)	(2,220,676)	(2,241,736)
Services and other expenses		(2,424,372)	(2,310,769)	(2,306,985)
Amortization of intangible assets		(181,472)	(180,614)	(178,778)
Goodwill, Impairment Loss		0	0	(80,000)
Segment profit (loss)		3,712,562	2,928,828	(93,336)
Interest expense		(204,300)	(185,077)	(196,062)
Net foreign exchange gains (losses)		129,438	(90,045)	137,832
Income (Loss) Before Income Taxes		3,637,700	2,653,706	(151,566)
Insurance [Member]
Segment Reporting Information [Line Items]
Earned premiums		7,407,643	7,282,705	6,528,263
Net investment income		0	0	0
Net investment gains (losses)		0	0	0
Products revenues		0	0	0
Services and other revenues		0	0	0
Total operating revenues		7,407,643	7,282,705	6,528,263
Attritional Current Year Claims and Claims Adjustment Expense		4,704,219	4,651,173	3,867,195
Catastrophe Current Year Claims and Claims Adjustment Expense		67,169	39,572	69,230
Losses and loss adjustment expenses, prior accident years		451,016	104,743	142,924
Amortization of policy acquisition costs		(1,501,829)	(1,508,169)	(1,375,539)
Other underwriting expenses		(1,163,557)	(1,026,358)	(809,352)
Products expenses		0	0	0
Services and other expenses		0	0	0
Segment profit (loss)		421,885	162,176	549,871
Reinsurance [Member]
Segment Reporting Information [Line Items]
Earned premiums		1,028,201	1,014,294	1,063,347
Net investment income		0	0	0
Net investment gains (losses)		0	0	0
Products revenues		0	0	0
Services and other revenues		0	0	0
Total operating revenues		1,028,201	1,014,294	1,063,347
Attritional Current Year Claims and Claims Adjustment Expense		733,191	669,314	663,903
Catastrophe Current Year Claims and Claims Adjustment Expense		3,480	500	12,707
Losses and loss adjustment expenses, prior accident years		12,344	(57,081)	26,052
Amortization of policy acquisition costs		(252,312)	(255,501)	(279,567)
Other underwriting expenses		(56,925)	(51,163)	(49,363)
Products expenses		0	0	0
Services and other expenses		0	0	0
Segment profit (loss)		(5,363)	(19,265)	83,859
Investing [Member]
Segment Reporting Information [Line Items]
Earned premiums		0	0	0
Net investment income		913,478	729,219	445,846
Net investment gains (losses)		1,807,219	1,524,054	(1,595,733)
Products revenues		0	0	0
Services and other revenues		52,253	(11,854)	(17,661)
Total operating revenues		2,772,950	2,241,419	(1,167,548)
Attritional Current Year Claims and Claims Adjustment Expense		0	0	0
Catastrophe Current Year Claims and Claims Adjustment Expense		0	0	0
Losses and loss adjustment expenses, prior accident years		0	0	0
Amortization of policy acquisition costs		0	0	0
Other underwriting expenses		0	0	0
Products expenses		0	0	0
Services and other expenses		0	0	0
Segment profit (loss)		2,772,950	2,241,419	(1,167,548)
Markel Ventures [Member]
Segment Reporting Information [Line Items]
Earned premiums		0	0	0
Net investment income		7,018	5,313	909
Net investment gains (losses)		0	0	0
Products revenues		2,635,659	2,545,053	2,427,096
Services and other revenues		2,477,419	2,434,715	2,329,522
Total operating revenues		5,120,096	4,985,081	4,757,527
Attritional Current Year Claims and Claims Adjustment Expense		0	0	0
Catastrophe Current Year Claims and Claims Adjustment Expense		0	0	0
Losses and loss adjustment expenses, prior accident years		0	0	0
Amortization of policy acquisition costs		0	0	0
Other underwriting expenses		0	0	0
Products expenses		(2,272,219)	(2,220,676)	(2,241,736)
Services and other expenses		(2,327,795)	(2,244,527)	(2,111,510)
Amortization of intangible assets		(81,317)	(82,370)
Segment profit (loss)		520,082	519,878	404,281
Other Insurance Operations
Segment Reporting Information [Line Items]
Earned premiums		(3,432)	(1,520)	(3,818)
Net investment income		0	0	0
Net investment gains (losses)		0	0	0
Products revenues		0	0	0
Services and other revenues		295,305	281,651	497,564
Total operating revenues		291,873	280,131	493,746
Attritional Current Year Claims and Claims Adjustment Expense		0	0	0
Catastrophe Current Year Claims and Claims Adjustment Expense		0	0	0
Losses and loss adjustment expenses, prior accident years		(8,050)	(9,112)	(1,530)
Amortization of policy acquisition costs		0	0	0
Other underwriting expenses		(2,766)	457	(1,762)
Products expenses		0	0	0
Services and other expenses		(96,577)	(66,242)	(195,475)
Amortization of intangible assets	[1]	(62,879)	(61,168)
Segment profit (loss)		184,480	205,234	294,979
Corporate Expense
Segment Reporting Information [Line Items]
Earned premiums		0	0	0
Net investment income		0	0	0
Net investment gains (losses)		0	0	0
Products revenues		0	0	0
Services and other revenues		0	0	0
Total operating revenues		0	0	0
Attritional Current Year Claims and Claims Adjustment Expense		0	0	0
Catastrophe Current Year Claims and Claims Adjustment Expense		0	0	0
Losses and loss adjustment expenses, prior accident years		0	0	0
Amortization of policy acquisition costs		0	0	0
Other underwriting expenses		0	0	0
Products expenses		0	0	0
Services and other expenses		0	0	0
Amortization of intangible assets		(181,472)	(180,614)	(178,778)
Goodwill, Impairment Loss				(80,000)
Segment profit (loss)		$ (181,472)	$ (180,614)	$ (258,778)
[1] Amounts included in other insurance operations reflect the Company's operations that are not included in a reportable segment and are primarily related to the Company's program services and insurance-linked securities operations.

Segment Reporting Disclosures_4

Segment Reporting Disclosures (Summary of Additional Measures for Markel Ventures) (Details) - Markel Ventures [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Depreciation	$ 122,125	$ 108,605	$ 102,055
Capital expenditure	$ 177,075	$ 221,036	$ 225,230

Segment Reporting Disclosures_5

Segment Reporting Disclosures (Reconciliation Of Segment Assets To The Company's Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Assets	$ 61,897,982	$ 55,045,710
Investing [Member]
Segment Reporting Information [Line Items]
Assets	34,272,049	30,542,282
Underwriting Operations [Member]
Segment Reporting Information [Line Items]
Assets	10,784,528	9,897,689
Markel Ventures [Member]
Segment Reporting Information [Line Items]
Assets	5,824,229	5,519,542
Other Insurance Operations
Segment Reporting Information [Line Items]
Assets	11,017,176	9,086,197
Segment Assets [Member]
Segment Reporting Information [Line Items]
Assets	$ 50,880,806	$ 45,959,513

Segment Reporting Disclosures_6

Segment Reporting Disclosures (Summary Of Segment Revenue By Product) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Product Information [Line Items]
Earned premiums	$ 8,432,412	$ 8,295,479	$ 7,587,792
Products revenues	2,635,659	2,545,053	2,427,096
Services and other revenues	2,824,977	2,704,512	2,809,425
Total products revenues and services and other revenues	5,460,636	5,249,565	5,236,521
Insurance [Member]
Product Information [Line Items]
Earned premiums	7,407,643	7,282,705	6,528,263
Products revenues	0	0	0
Services and other revenues	0	0	0
Insurance [Member] | General liability [Member]
Product Information [Line Items]
Earned premiums	2,063,827	2,128,317	1,927,721
Insurance [Member] | Professional liability [Member]
Product Information [Line Items]
Earned premiums	1,655,848	1,798,882	1,739,983
Insurance [Member] | Marine and energy [Member]
Product Information [Line Items]
Earned premiums	747,004	688,591	585,885
Insurance [Member] | Personal Lines [Member]
Product Information [Line Items]
Earned premiums	625,542	538,816	489,648
Insurance [Member] | Property [Member]
Product Information [Line Items]
Earned premiums	609,453	532,337	428,563
Insurance [Member] | Programs [Member]
Product Information [Line Items]
Earned premiums	576,444	509,866	384,952
Insurance [Member] | Workers' compensation [Member]
Product Information [Line Items]
Earned premiums	374,371	393,011	385,054
Insurance [Member] | Credit and surety [Member]
Product Information [Line Items]
Earned premiums	248,001	219,542	193,701
Insurance [Member] | Other products [Member]
Product Information [Line Items]
Earned premiums	507,153	473,343	392,756
Reinsurance [Member]
Product Information [Line Items]
Earned premiums	1,028,201	1,014,294	1,063,347
Products revenues	0	0	0
Services and other revenues	0	0	0
Reinsurance [Member] | General liability [Member]
Product Information [Line Items]
Earned premiums	382,151	368,376	382,482
Reinsurance [Member] | Professional liability [Member]
Product Information [Line Items]
Earned premiums	371,198	388,610	398,839
Reinsurance [Member] | Specialty [Member]
Product Information [Line Items]
Earned premiums	269,021	245,126	275,033
Reinsurance [Member] | Property [Member]
Product Information [Line Items]
Earned premiums	5,831	12,182	6,993
Other [Member]
Product Information [Line Items]
Earned premiums	(3,432)	(1,520)	(3,818)
Total products revenues and services and other revenues	347,558	269,797	479,903
Markel Ventures [Member]
Product Information [Line Items]
Earned premiums	0	0	0
Products revenues	2,635,659	2,545,053	2,427,096
Services and other revenues	2,477,419	2,434,715	2,329,522
Total products revenues and services and other revenues	5,113,078	4,979,768	4,756,618
Markel Ventures [Member] | Consumer and building
Product Information [Line Items]
Products revenues	1,606,353	1,474,499	1,510,130
Markel Ventures [Member] | Transportation-related
Product Information [Line Items]
Products revenues	584,200	667,040	612,467
Markel Ventures [Member] | Equipment manufacturing
Product Information [Line Items]
Products revenues	445,106	403,514	304,499
Markel Ventures [Member] | Construction
Product Information [Line Items]
Services and other revenues	2,089,280	2,042,326	1,910,403
Markel Ventures [Member] | Consulting
Product Information [Line Items]
Services and other revenues	283,343	297,115	326,549
Markel Ventures [Member] | Other services
Product Information [Line Items]
Services and other revenues	$ 104,796	$ 95,274	$ 92,570

Segment Reporting Disclosures_7

Segment Reporting Disclosures (Summary of Top Five Independent Brokers Concentration) (Details) - Top Five Independent Brokers	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Insurance [Member]
Summary of Top Five Independent Brokers Concentration [Line Items]
Percentage of gross premiums written	32%	33%	34%
Reinsurance [Member]
Summary of Top Five Independent Brokers Concentration [Line Items]
Percentage of gross premiums written	90%	95%	99%
Underwriting Operations [Member]
Summary of Top Five Independent Brokers Concentration [Line Items]
Percentage of gross premiums written	38%	37%	40%

Segment Reporting Disclosures_8

Segment Reporting Disclosures (Summary of Gross Premium Volume and Net Written Premiums) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of GWP and NWP, by Segment [Line Items]
Gross written premiums	$ 15,494,631	$ 14,002,237	$ 13,201,682
Net written premiums	8,296,175	8,397,575	8,203,390
Underwriting Operations [Member]
Schedule of GWP and NWP, by Segment [Line Items]
Gross written premiums	10,551,873	10,277,632	9,847,538
Net written premiums	8,299,751	8,398,788	8,207,373
Insurance [Member]
Schedule of GWP and NWP, by Segment [Line Items]
Gross written premiums	9,400,316	9,217,150	8,606,700
Net written premiums	7,260,089	7,432,062	7,040,176
Reinsurance [Member]
Schedule of GWP and NWP, by Segment [Line Items]
Gross written premiums	1,150,780	1,046,539	1,229,851
Net written premiums	1,039,372	967,799	1,167,312
Other underwriting [Member]
Schedule of GWP and NWP, by Segment [Line Items]
Gross written premiums	777	13,943	10,987
Net written premiums	290	(1,073)	(115)
Fronting [Member]
Schedule of GWP and NWP, by Segment [Line Items]
Gross written premiums	4,942,758	3,724,605	3,354,144
Net written premiums	$ (3,576)	$ (1,213)	$ (3,983)

Segment Reporting Disclosures_9

Segment Reporting Disclosures (Summary Of Deferred Policy Acquisition Costs, Unearned Premiums And Unpaid Losses And Loss Adjustment Expenses) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Deferred policy acquisition costs	$ 875,710	$ 931,344
Unearned premiums	7,063,956	6,642,426
Unpaid losses and loss adjustment expenses	26,633,094	23,483,321	$ 20,947,898	$ 18,178,894
Underwriting Operations [Member]
Segment Reporting Information [Line Items]
Deferred policy acquisition costs	875,710	931,344
Unearned premiums	5,218,766	5,216,330
Unpaid losses and loss adjustment expenses	20,092,936	18,112,801
Market CATCo Re
Segment Reporting Information [Line Items]
Unpaid losses and loss adjustment expenses	25,005	184,967
Insurance [Member]
Segment Reporting Information [Line Items]
Deferred policy acquisition costs	648,969	708,128
Unearned premiums	4,283,879	4,307,704
Unpaid losses and loss adjustment expenses	16,073,355	14,221,258
Reinsurance [Member]
Segment Reporting Information [Line Items]
Deferred policy acquisition costs	226,741	223,216
Unearned premiums	933,329	901,138
Unpaid losses and loss adjustment expenses	3,870,059	3,726,472
Other underwriting [Member]
Segment Reporting Information [Line Items]
Deferred policy acquisition costs	0	0
Unearned premiums	1,558	7,488
Unpaid losses and loss adjustment expenses	149,522	165,071
Fronting [Member]
Segment Reporting Information [Line Items]
Deferred policy acquisition costs	0	0
Unearned premiums	1,845,190	1,426,096
Unpaid losses and loss adjustment expenses	6,515,153	5,185,553
Market CATCo Re
Segment Reporting Information [Line Items]
Deferred policy acquisition costs	0	0
Unearned premiums	0	0
Unpaid losses and loss adjustment expenses	$ 25,005	$ 184,967

Acquisitions and Dispositions (

Acquisitions and Dispositions (Narrative) (Details) - USD ($) $ in Thousands					12 Months Ended
	Jun. 28, 2024	Jun. 01, 2023	Oct. 01, 2022	Feb. 01, 2022	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Sep. 12, 2024
Schedule of Business Dispositions, by Dispositions [Line Items]
Gain on sale of business					$ 0	$ 18,965	$ 225,832
Business Acquisition [Line Items]
Goodwill, Acquired During Period					114,589
Schedule of Equity Method Investments [Line Items]
Equity method investments					$ 862,500	$ 605,900
Educational Partners International [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage								68%
Equity method investments								$ 167,700
Volante [Member]
Schedule of Business Dispositions, by Dispositions [Line Items]
Total sale consideration			$ 181,900
Proceeds from sale of business			155,600
Gain on sale of business			$ 118,500
Velocity [Member]
Schedule of Business Dispositions, by Dispositions [Line Items]
Total sale consideration				$ 181,300
Gain on sale of business				$ 107,300
ISIC [Member]
Schedule of Business Dispositions, by Dispositions [Line Items]
Gain on sale of business		$ 16,900
Valor Environmental [Member]
Business Acquisition [Line Items]
Percentage acquired	98%
Total purchase consideration	$ 156,400
Cash consideration	156,400
Goodwill, Acquired During Period	107,500
Goodwill, tax deductible	0
Finite-lived intangible assets	$ 49,000

Investments (Narrative) (Detail

Investments (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($) securities	Dec. 31, 2023 USD ($) securities
Investments, Debt and Equity Securities [Abstract]
Available-for-sale fixed maturity securities in unrealized loss position, number of positions | securities	1,485	1,386
Available-for-sale fixed maturity securities in unrealized loss position, number of positions, 12 months or longer | securities	966	1,131
Available-for-sale fixed maturity securities, estimated fair value	$ 12,570,401	$ 9,982,329
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	743,003	661,282
Available-for-sale fixed maturity securities, estimated fair value, 12 months or longer	7,448,033	8,515,061
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 633,124	$ 650,461
Estimated average duration of fixed maturities	3 years 10 months 24 days
Percentage threshold of shareholders' equity used to define concentration of investments	10%	10%

Investments (Available-For-Sale

Investments (Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	$ 16,457,723
Available-for-sale fixed maturity investments, estimated fair value	15,745,539	$ 14,372,732
Short-term investments, available-for-sale, amortized cost basis	2,530,941	2,564,620
Short-term investments, available-for-sale, accumulated gross unrealized gain before tax	548	7,155
Short-term investments, available-for-sale, accumulated gross unrealized loss before tax	(6,579)	(393)
Short-term investments, available-for-sale	2,524,910	2,571,382
Investments, available-for-sale, amortized cost basis	18,988,664	17,496,906
Investments, available-for-sale, accumulated gross unrealized gain before tax	24,788	108,490
Investments, available-for-sale, accumulated gross unrealized loss before tax	(743,003)	(661,282)
Investments, available-for-sale	18,270,449	16,944,114
Investments, Available-for-sale, Allowance for Credit Loss	0	0
U.S. Treasury securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	5,147,365	3,811,293
Available-for-sale fixed maturity investments, gross unrealized holding gains	8,962	35,824
Available-for-sale fixed maturity investments, gross unrealized holding losses	(68,469)	(62,404)
Available-for-sale fixed maturity investments, estimated fair value	5,087,858	3,784,713
U.S. government-sponsored enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	1,445,171	1,225,426
Available-for-sale fixed maturity investments, gross unrealized holding gains	2,976	7,292
Available-for-sale fixed maturity investments, gross unrealized holding losses	(101,911)	(89,904)
Available-for-sale fixed maturity investments, estimated fair value	1,346,236	1,142,814
Obligations of states, municipalities and political subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	3,813,146	4,196,096
Available-for-sale fixed maturity investments, gross unrealized holding gains	5,866	14,787
Available-for-sale fixed maturity investments, gross unrealized holding losses	(199,520)	(181,578)
Available-for-sale fixed maturity investments, estimated fair value	3,619,492	4,029,305
Foreign governments [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	2,909,561	2,554,874
Available-for-sale fixed maturity investments, gross unrealized holding gains	4,264	34,352
Available-for-sale fixed maturity investments, gross unrealized holding losses	(207,302)	(142,008)
Available-for-sale fixed maturity investments, estimated fair value	2,706,523	2,447,218
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	2,771,589	2,507,682
Available-for-sale fixed maturity investments, gross unrealized holding gains	2,096	8,939
Available-for-sale fixed maturity investments, gross unrealized holding losses	(123,872)	(135,611)
Available-for-sale fixed maturity investments, estimated fair value	2,649,813	2,381,010
Non-agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	122,373	355,673
Available-for-sale fixed maturity investments, gross unrealized holding gains	0	0
Available-for-sale fixed maturity investments, gross unrealized holding losses	(4,343)	(22,603)
Available-for-sale fixed maturity investments, estimated fair value	118,030	333,070
Corporate bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	248,518	281,242
Available-for-sale fixed maturity investments, gross unrealized holding gains	76	141
Available-for-sale fixed maturity investments, gross unrealized holding losses	(31,007)	(26,781)
Available-for-sale fixed maturity investments, estimated fair value	217,587	254,602
Total fixed maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	16,457,723	14,932,286
Available-for-sale fixed maturity investments, gross unrealized holding gains	24,240	101,335
Available-for-sale fixed maturity investments, gross unrealized holding losses	(736,424)	(660,889)
Available-for-sale fixed maturity investments, estimated fair value	$ 15,745,539	$ 14,372,732

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	Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity securities, estimated fair value, less than 12 months	$ 5,122,368	$ 1,467,268
Available-for-sale fixed maturity securities, gross unrealized holding, less than 12 months	(109,879)	(10,821)
Available-for-sale fixed maturity securities, estimated fair value, 12 months or longer	7,448,033	8,515,061
Available-for-sale fixed maturity securities, gross unrealized holding losses, 12 months or longer	(633,124)	(650,461)
Available-for-sale fixed maturity securities, estimated fair value	12,570,401	9,982,329
Available-for-sale fixed maturity securities, gross unrealized holding losses	(743,003)	(661,282)
Short-term investments, available-for-sale, continuous unrealized loss position, less than 12 months	163,503	52,601
Short-term investments, available-for-sale, continuous unrealized loss position, less than 12 months, accumulated loss	(6,579)	(393)
Short-term investments, available-for-sale, continuous unrealized loss position, 12 months or longer	0	0
Short-term investments, available-for-sale, continuous unrealized loss position, 12 months or longer, accumulated loss	0	0
Short-term investments, available-for-sale, unrealized loss position, total	163,503	52,601
Short-term investments, available-for-sale, unrealized loss position, accumulated loss	(6,579)	(393)
U.S. Treasury securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity securities, estimated fair value, less than 12 months	1,593,711	317,027
Available-for-sale fixed maturity securities, gross unrealized holding, less than 12 months	(27,213)	(2,147)
Available-for-sale fixed maturity securities, estimated fair value, 12 months or longer	1,444,869	1,507,784
Available-for-sale fixed maturity securities, gross unrealized holding losses, 12 months or longer	(41,256)	(60,257)
Available-for-sale fixed maturity securities, estimated fair value	3,038,580	1,824,811
Available-for-sale fixed maturity securities, gross unrealized holding losses	(68,469)	(62,404)
U.S. government-sponsored enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity securities, estimated fair value, less than 12 months	415,333	145,143
Available-for-sale fixed maturity securities, gross unrealized holding, less than 12 months	(10,938)	(2,134)
Available-for-sale fixed maturity securities, estimated fair value, 12 months or longer	691,781	723,537
Available-for-sale fixed maturity securities, gross unrealized holding losses, 12 months or longer	(90,973)	(87,770)
Available-for-sale fixed maturity securities, estimated fair value	1,107,114	868,680
Available-for-sale fixed maturity securities, gross unrealized holding losses	(101,911)	(89,904)
Obligations of states, municipalities and political subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity securities, estimated fair value, less than 12 months	1,133,275	679,124
Available-for-sale fixed maturity securities, gross unrealized holding, less than 12 months	(21,242)	(3,881)
Available-for-sale fixed maturity securities, estimated fair value, 12 months or longer	2,024,298	2,332,281
Available-for-sale fixed maturity securities, gross unrealized holding losses, 12 months or longer	(178,278)	(177,697)
Available-for-sale fixed maturity securities, estimated fair value	3,157,573	3,011,405
Available-for-sale fixed maturity securities, gross unrealized holding losses	(199,520)	(181,578)
Foreign governments [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity securities, estimated fair value, less than 12 months	1,056,877	83,396
Available-for-sale fixed maturity securities, gross unrealized holding, less than 12 months	(29,890)	(394)
Available-for-sale fixed maturity securities, estimated fair value, 12 months or longer	1,246,215	1,492,912
Available-for-sale fixed maturity securities, gross unrealized holding losses, 12 months or longer	(177,412)	(141,614)
Available-for-sale fixed maturity securities, estimated fair value	2,303,092	1,576,308
Available-for-sale fixed maturity securities, gross unrealized holding losses	(207,302)	(142,008)
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity securities, estimated fair value, less than 12 months	757,562	189,977
Available-for-sale fixed maturity securities, gross unrealized holding, less than 12 months	(13,880)	(1,872)
Available-for-sale fixed maturity securities, estimated fair value, 12 months or longer	1,710,436	1,889,272
Available-for-sale fixed maturity securities, gross unrealized holding losses, 12 months or longer	(109,992)	(133,739)
Available-for-sale fixed maturity securities, estimated fair value	2,467,998	2,079,249
Available-for-sale fixed maturity securities, gross unrealized holding losses	(123,872)	(135,611)
Non-agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity securities, estimated fair value, less than 12 months	0	0
Available-for-sale fixed maturity securities, gross unrealized holding, less than 12 months	0	0
Available-for-sale fixed maturity securities, estimated fair value, 12 months or longer	118,030	333,070
Available-for-sale fixed maturity securities, gross unrealized holding losses, 12 months or longer	(4,343)	(22,603)
Available-for-sale fixed maturity securities, estimated fair value	118,030	333,070
Available-for-sale fixed maturity securities, gross unrealized holding losses	(4,343)	(22,603)
Corporate bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity securities, estimated fair value, less than 12 months	2,107	0
Available-for-sale fixed maturity securities, gross unrealized holding, less than 12 months	(137)	0
Available-for-sale fixed maturity securities, estimated fair value, 12 months or longer	212,404	236,205
Available-for-sale fixed maturity securities, gross unrealized holding losses, 12 months or longer	(30,870)	(26,781)
Available-for-sale fixed maturity securities, estimated fair value	214,511	236,205
Available-for-sale fixed maturity securities, gross unrealized holding losses	(31,007)	(26,781)
Total fixed maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity securities, estimated fair value, less than 12 months	4,958,865	1,414,667
Available-for-sale fixed maturity securities, gross unrealized holding, less than 12 months	(103,300)	(10,428)
Available-for-sale fixed maturity securities, estimated fair value, 12 months or longer	7,448,033	8,515,061
Available-for-sale fixed maturity securities, gross unrealized holding losses, 12 months or longer	(633,124)	(650,461)
Available-for-sale fixed maturity securities, estimated fair value	12,406,898	9,929,728
Available-for-sale fixed maturity securities, gross unrealized holding losses	$ (736,424)	$ (660,889)

Investments (Schedule Of Amorti

Investments (Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Due in one year or less, amortized cost	$ 1,593,149
Due after one year through five years, amortized cost	6,071,013
Due after five years through ten years, amortized cost	4,647,538
Due after ten years, amortized cost	1,252,061
Amortized cost, sub-total	13,563,761
Fixed maturities, amortized cost	16,457,723
Due in one year or less, estimated fair value	1,571,022
Due after one year through five years, estimated fair value	5,901,682
Due after five years through ten years, estimated fair value	4,406,225
Due after ten years, estimated fair value	1,098,767
Estimated fair value, sub-total	12,977,696
Available-for-sale fixed maturity investments, estimated fair value	15,745,539	$ 14,372,732
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost	2,893,962
Estimated fair value	$ 2,767,843

Investments (Components Of Net

Investments (Components Of Net Investment Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Dividends on equity securities	$ 142,367	$ 116,911	$ 107,213
Total investment income	938,474	751,754	464,013
Investment expenses	(17,978)	(17,222)	(17,258)
Net investment income	920,496	734,532	446,755
Fixed maturities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Interest income	510,044	383,022	294,417
Short-term investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Interest income	124,575	106,747	33,493
Cash and cash equivalents [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Interest income	$ 161,488	$ 145,074	$ 28,890

Investments (Net Investment Gai

Investments (Net Investment Gains (Losses) and Change in Net Unrealized Gains On Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	$ 4,423	$ (42,177)	$ (40,983)
Change in fair value of equity securities sold during the period	(14,966)	34,684	(14,884)
Change in fair value of equity securities held at the end of the period	1,817,762	1,531,547	(1,539,866)
Change in fair value of equity securities	1,802,796	1,566,231	(1,554,750)
Net investment gains (losses)	1,807,219	1,524,054	(1,595,733)
Change in net unrealized gains on investments included in other comprehensive income (loss)	(165,423)	390,558	(1,463,876)
Fixed maturities [Member]
Gain (Loss) on Securities [Line Items]
Change in net unrealized gains on investments included in other comprehensive income (loss)	(152,630)	389,498	(1,474,890)
Short-term investments [Member]
Gain (Loss) on Securities [Line Items]
Change in net unrealized gains on investments included in other comprehensive income (loss)	$ (12,793)	$ 1,060	$ 11,014

Investments (Schedule Of Restri

Investments (Schedule Of Restricted Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Restricted fixed maturity securities	$ 3,027,863	$ 3,102,899
Restricted equity securities	915,242	1,004,347
Restricted short-term investments	704,201	807,138
Restricted cash and cash equivalents	499,581	584,974
Total	$ 5,146,887	$ 5,499,358

Investments Investments (Compon

Investments Investments (Components Of Restricted Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Components Of Restricted Assets [Line Items]
Restricted assets	$ 5,146,887	$ 5,499,358
Assets held in trust or on deposit to support underwriting activities [Member]
Components Of Restricted Assets [Line Items]
Restricted assets	4,727,799	5,048,857
Assets pledged as security for letters of credit [Member]
Components Of Restricted Assets [Line Items]
Restricted assets	$ 419,088	$ 450,501

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - Fair Value, Nonrecurring [Member] - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 0	$ 0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 0	$ 0

Fair Value Measurements (Balanc

Fair Value Measurements (Balances Of Assets Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 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	$ 15,745,539	$ 14,372,732
Equity securities	11,784,521	9,577,871
Short-term investments	2,524,910	2,571,382
Investments	30,054,970	26,521,985
Fixed maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	15,745,539	14,372,732
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	5,087,858	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	1,346,236	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	3,619,492	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	2,706,523	2,447,218
Agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	2,649,813	2,381,010
Non-agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	118,030	333,070
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	217,587	254,602
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	11,784,521	9,577,871
Short-term investments	2,524,910	2,571,382
Investments	30,054,970	26,521,985
Fair Value, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	11,783,137	9,576,877
Short-term investments	2,363,736	2,402,099
Investments	14,146,873	11,978,976
Fair Value, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0	0
Short-term investments	161,174	169,283
Investments	15,906,713	14,542,015
Fair Value, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	1,384	994
Short-term investments	0	0
Investments	1,384	994
Fair Value, Recurring [Member] | Fixed maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	15,745,539	14,372,732
Fair Value, Recurring [Member] | Fixed maturities [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] | Fixed maturities [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	15,745,539	14,372,732
Fair Value, Recurring [Member] | Fixed maturities [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. 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	5,087,858	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	5,087,858	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	1,346,236	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	1,346,236	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	3,619,492	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	3,619,492	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	2,706,523	2,447,218
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	2,706,523	2,447,218
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] | Agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	2,649,813	2,381,010
Fair Value, Recurring [Member] | Agency mortgage-backed securities | 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] | Agency mortgage-backed securities | 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	2,649,813	2,381,010
Fair Value, Recurring [Member] | Agency mortgage-backed securities | 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] | Non-agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	118,030	333,070
Fair Value, Recurring [Member] | Non-agency mortgage-backed securities | 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] | Non-agency mortgage-backed securities | 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	118,030	333,070
Fair Value, Recurring [Member] | Non-agency mortgage-backed securities | 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	217,587	254,602
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	217,587	254,602
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	4,970,120	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	4,968,736	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	1,384	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	6,814,401	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	6,814,401	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	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 862.5	$ 605.9
Income (loss) from equity method investments	58.7	(2.1)	$ (22.9)
Hagerty [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 264.7	$ 237.4
Equity method investment, ownership percentage	23%	23%
Equity method investment, quoted market value	$ 753.7	$ 608.4

Receivables (Details)

Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	$ 3,660,108	$ 3,486,395
Allowance for credit losses	(33,309)	(31,089)
Receivables	3,626,799	3,455,306
Insurance operation
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amounts receivable from agents, brokers and insureds	2,870,719	2,686,199
Receivables, gross	124,258	117,436
Markel Ventures [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	638,480	657,156
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	$ 26,651	$ 25,604

Goodwill And Intangible Asset_2

Goodwill And Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024		Dec. 31, 2023		Dec. 31, 2022
Goodwill And Intangible Assets [Line Items]
Impairment of goodwill	$ 0		$ 0		$ 80,000
Impairment of intangible assets (excluding goodwill)	0		0		0
Goodwill, carrying value	2,735,867	[1]	2,624,749	[1]	2,638,838
Estimated amortization of intangible assets for 2025	172,700
Estimated amortization of intangible assets for 2026	165,500
Estimated amortization of intangible assets for 2027	154,900
Estimated amortization of intangible assets for 2028	146,100
Estimated amortization of intangible assets for 2029	142,000
Indefinite-lived intangible assets	$ 90,400		$ 90,400
Nephila Holdings Limited [Member]
Goodwill And Intangible Assets [Line Items]
Impairment of goodwill					80,000
Goodwill, carrying value					$ 221,800
[1] As of December 31, 2024 and 2023, goodwill was net of accumulated impairment losses of $190.6 million, of which $171.9 million was in other insurance operations and $18.7 million was in Markel Ventures.

Goodwill And Intangible Asset_3

Goodwill And Intangible Assets (Components Of Goodwill) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024		Dec. 31, 2023
Goodwill [Line Items]
Goodwill, beginning balance		$ 2,624,749	[1]	$ 2,638,838
Goodwill, Acquired During Period		114,589
Goodwill, Adjustments to preliminary purchase price allocation				(16,752)
Foreign currency movements and other adjustments		(3,471)		2,663
Goodwill, ending balance	[1]	2,735,867		2,624,749
Accumulated impairment losses	[1]	190,600		190,600
Insurance [Member]
Goodwill [Line Items]
Goodwill, beginning balance		772,823	[1]	771,628
Goodwill, Acquired During Period		0
Goodwill, Adjustments to preliminary purchase price allocation				0
Foreign currency movements and other adjustments		(3,247)		1,195
Goodwill, ending balance	[1]	769,576		772,823
Reinsurance [Member]
Goodwill [Line Items]
Goodwill, beginning balance		122,745	[1]	122,745
Goodwill, Acquired During Period		0
Goodwill, Adjustments to preliminary purchase price allocation				0
Foreign currency movements and other adjustments		0		0
Goodwill, ending balance	[1]	122,745		122,745
Markel Ventures [Member]
Goodwill [Line Items]
Goodwill, beginning balance		1,137,654	[1]	1,153,909
Goodwill, Acquired During Period		114,589
Goodwill, Adjustments to preliminary purchase price allocation				(16,752)
Foreign currency movements and other adjustments		(434)		497
Goodwill, ending balance	[1]	1,251,809		1,137,654
Accumulated impairment losses	[1]	18,700		18,700
Other Insurance Operations
Goodwill [Line Items]
Goodwill, beginning balance	[2]	591,527	[1]	590,556
Goodwill, Acquired During Period	[2]	0
Goodwill, Adjustments to preliminary purchase price allocation	[2]			0
Foreign currency movements and other adjustments	[2]	210		971
Goodwill, ending balance	[1],[2]	591,737		591,527
Accumulated impairment losses	[1]	$ 171,900		$ 171,900
[1] As of December 31, 2024 and 2023, goodwill was net of accumulated impairment losses of $190.6 million, of which $171.9 million was in other insurance operations and $18.7 million was in Markel Ventures. Amounts included in other insurance operations reflect the Company's operations that are not included in a reportable segment and are primarily related to the Company's program services and insurance-linked securities operations.

Goodwill And Intangible Asset_4

Goodwill And Intangible Assets Goodwill And Intangible Assets (Components of Net Intangible Assets) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Intangible [Line Items]
Net intangible assets, beginning balance		$ 1,588,684	$ 1,747,464
Intangible Assets Acquired During Period		52,909
Dispositions			(2,000)
Amortization of intangible assets		(181,472)	(180,614)	$ (178,778)
Adjustments to preliminary purchase price allocation			22,671
Foreign currency movements and other adjustments		(501)	1,163
Net intangible assets, ending balance		1,459,620	1,588,684	1,747,464
Underwriting [Member]
Intangible [Line Items]
Net intangible assets, beginning balance	[1]	325,344	362,322
Intangible Assets Acquired During Period	[1]	0
Dispositions			0
Amortization of intangible assets	[1]	37,276	37,076
Adjustments to preliminary purchase price allocation			0
Foreign currency movements and other adjustments	[1]	(117)	98
Net intangible assets, ending balance	[1]	287,951	325,344	362,322
Markel Ventures [Member]
Intangible [Line Items]
Net intangible assets, beginning balance		736,717	796,297
Intangible Assets Acquired During Period		52,909
Dispositions			0
Amortization of intangible assets		(81,317)	(82,370)
Adjustments to preliminary purchase price allocation			22,671
Foreign currency movements and other adjustments		154	119
Net intangible assets, ending balance		708,463	736,717	796,297
Other Insurance Operations
Intangible [Line Items]
Net intangible assets, beginning balance	[2]	526,623	588,845
Intangible Assets Acquired During Period	[2]	0
Dispositions			(2,000)
Amortization of intangible assets	[2]	(62,879)	(61,168)
Adjustments to preliminary purchase price allocation			0
Foreign currency movements and other adjustments	[2]	(538)	946
Net intangible assets, ending balance	[2]	$ 463,206	$ 526,623	$ 588,845
[1] Amounts included in Underwriting reflect the intangible assets associated with the Company's underwriting segments, which are not allocated between the Insurance and Reinsurance segments. Amounts included in other insurance operations reflect the Company's operations that are not included in a reportable segment and are primarily related to the Company's program services and insurance-linked securities operations.

Goodwill And Intangible Asset_5

Goodwill And Intangible Assets (Components Of Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Schedule of Indefinite-Lived And Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	$ 2,898,994	$ 2,860,728
Intangible assets, accumulated amortization	(1,439,374)	(1,272,044)
Customer Relationships [Member]
Schedule of Indefinite-Lived And Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	1,488,796	1,450,503
Intangible assets, accumulated amortization	(699,550)	(600,724)
Investment Management Agreements [Member]
Schedule of Indefinite-Lived And Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	464,000	464,000
Intangible assets, accumulated amortization	(178,727)	(149,560)
Broker and Agent Relationships [Member]
Schedule of Indefinite-Lived And Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	295,694	297,693
Intangible assets, accumulated amortization	(182,139)	(168,586)
Trade Names [Member]
Schedule of Indefinite-Lived And Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	305,381	293,270
Intangible assets, accumulated amortization	(157,494)	(138,040)
Technology [Member]
Schedule of Indefinite-Lived And Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	113,187	113,248
Intangible assets, accumulated amortization	(107,727)	(100,781)
Insurance Licenses [Member]
Schedule of Indefinite-Lived And Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	72,333	72,333
Intangible assets, accumulated amortization	0	0
Other [Member]
Schedule of Indefinite-Lived And Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	159,603	169,681
Intangible assets, accumulated amortization	$ (113,737)	$ (114,353)

Leases (Narrative) (Details)

Leases (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Maximum remaining term of noncancelable leases	18 years
Operating Lease, Expense	$ 169	$ 148.4	$ 126.3
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 111.3	$ 130.2	$ 64.4

Leases (Summary of Supplementar

Leases (Summary of Supplementary Balance Sheet Information) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Lessee, Lease, Description [Line Items]
Operating lease, right-of-use asset	$ 681,405	$ 628,833
Operating lease, liability	$ 723,924	$ 657,217
Operating lease, weighted average remaining lease term	9 years	9 years 9 months 18 days
Operating lease, weighted average discount rate, percent	4.30%	5.20%
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities	Other liabilities
Other Liabilities [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities

Leases (Maturities of Operating

Leases (Maturities of Operating Lease Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Leases [Abstract]
Lessee, operating lease, liability, payments, due next twelve months	$ 130,943
Lessee, operating lease, liability, payments, due year two	116,324
Lessee, operating lease, liability, payments, due year three	100,927
Lessee, operating lease, liability, payments, due year four	88,473
Lessee, operating lease, liability, payments, due year five	77,206
Lessee, operating lease, liability, payments, due after year five	368,468
Lessee, operating lease, liability, payments, due	882,341
Lessee, operating lease, liability, undiscounted excess amount	(158,417)
Operating lease, liability	723,924	$ 657,217
Lessee, Lease, Description [Line Items]
Operating lease, liability	$ 723,924	$ 657,217
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities	Other liabilities
Other Liabilities [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities

Products, Services and Other _3

Products, Services and Other Revenues (Schedule Of Revenues From Contracts With Customers By Type) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Leasing revenues	$ 176,293	$ 188,904	$ 157,552
Fronting fees	187,480	154,838	147,612
Equity method and other investments income (loss)	58,830	(13,598)	(15,120)
Disposition gains	0	16,923	225,828
Other	7,211	42,733	33,970
Total products revenues and services and other revenues	5,460,636	5,249,565	5,236,521
Markel Ventures [Member]
Disaggregation of Revenue [Line Items]
Leasing revenues	176,293	188,904	157,552
Fronting fees	0	0	0
Equity method and other investments income (loss)	6,577	(1,744)	2,541
Disposition gains	0	0	0
Other	6,805	42,693	32,930
Total products revenues and services and other revenues	5,113,078	4,979,768	4,756,618
Other [Member]
Disaggregation of Revenue [Line Items]
Leasing revenues	0	0	0
Fronting fees	187,480	154,838	147,612
Equity method and other investments income (loss)	52,253	(11,854)	(17,661)
Disposition gains	0	16,923	225,828
Other	406	40	1,040
Total products revenues and services and other revenues	347,558	269,797	479,903
Revenue from Contract with Customer [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5,030,822	4,859,765	4,686,679
Revenue from Contract with Customer [Member] | Products [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,607,581	2,487,054	2,379,399
Revenue from Contract with Customer [Member] | Services [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,326,015	2,273,202	2,228,071
Revenue from Contract with Customer [Member] | Management Fees [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	97,226	99,509	79,209
Revenue from Contract with Customer [Member] | Markel Ventures [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,923,403	4,749,915	4,563,595
Revenue from Contract with Customer [Member] | Markel Ventures [Member] | Products [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,607,581	2,487,054	2,379,399
Revenue from Contract with Customer [Member] | Markel Ventures [Member] | Services [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,315,822	2,262,861	2,184,196
Revenue from Contract with Customer [Member] | Markel Ventures [Member] | Management Fees [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Revenue from Contract with Customer [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	107,419	109,850	123,084
Revenue from Contract with Customer [Member] | Other [Member] | Products [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Revenue from Contract with Customer [Member] | Other [Member] | Services [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	10,193	10,341	43,875
Revenue from Contract with Customer [Member] | Other [Member] | Management Fees [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 97,226	$ 99,509	$ 79,209

Products, Services and Other _4

Products, Services and Other Revenues Products, Services and Other Revenues (Receivables Related To Contracts With Customers) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Receivables [Line Items]
Trade and other receivables	$ 3,660,108	$ 3,486,395
Contracts with customers [Member]
Receivables [Line Items]
Trade and other receivables	$ 593,800	$ 616,400

Unpaid Losses And Loss Adjust_3

Unpaid Losses And Loss Adjustment Expenses (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Jul. 02, 2024	Dec. 31, 2021
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss adjustment expenses	$ 5,508,059	$ 5,360,559	$ 4,613,035
Unpaid losses and loss adjustment expenses	26,633,094	23,483,321	20,947,898		$ 18,178,894
Reinsurance recoverables on unpaid losses, end of year	11,120,367	8,820,567	7,994,884		$ 6,876,317
Reinsurance Recoverable, Retroactive Reinsurance Transaction	$ 0	$ (125,067)	0
IBNR reserves as a percentage of total unpaid losses and loss adjustment expenses	71%	72%
Prior Year Claims and Claims Adjustment Expense	$ 455,300	$ 38,600	167,400
Insurance [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Unpaid losses and loss adjustment expenses	16,073,355	14,221,258
Prior Year Claims and Claims Adjustment Expense	451,000	104,700	142,900
Insurance [Member] | Accident Years 2014 and Prior [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense	50,100
Reinsurance [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Unpaid losses and loss adjustment expenses	3,870,059	3,726,472
Prior Year Claims and Claims Adjustment Expense	12,300	(57,100)	26,100
Reinsurance [Member] | 2023 U.K. Motor Retroactive Transaction
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Reinsurance Recoverable, Retroactive Reinsurance Transaction		(125,100)
Fronting [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Reinsurance recoverables	3,500,000	2,500,000	3,000,000
Unpaid losses and loss adjustment expenses	6,515,153	5,185,553
Asbestos [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Asbestos-related reserves, gross loss incurred	122,100	132,500
Asbestos-related reserves, net loss incurred	32,500	39,600
Casualty policy portfolio part of retroactive reinsurance contract | Fronting [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Unpaid losses and loss adjustment expenses				$ 302,600
Reinsurance recoverables on unpaid losses, end of year				$ 302,600
2024 Catastrophes
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss adjustment expenses	70,600
Reinsurance recoverables	$ 60,400
2023 Catastrophes | Insurance [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss adjustment expenses		40,100
Reinsurance recoverables		$ 9,300
Hurricane Ian
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss adjustment expenses			46,200
Reinsurance recoverables			115,300
Russia-Ukraine conflict
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss adjustment expenses			35,700
Reinsurance recoverables			$ 44,300

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	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
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	$ 18,178,894
Reinsurance recoverables on unpaid losses, beginning of year	8,820,567	7,994,884	6,876,317
Net reserves for losses and loss adjustment expenses, beginning of year	14,662,754	12,953,014	11,302,577
Effect of foreign currency rate changes on beginning of year balance	(78,702)	70,344	(160,622)
Adjusted net reserves for losses and loss adjustment expenses, beginning of year	14,584,052	13,023,358	11,141,955
Incurred losses and loss adjustment expenses, current accident year	5,508,059	5,360,559	4,613,035
Incurred losses and loss adjustment expenses, prior accident years (including deposit liability)	(455,310)	(38,550)	(167,446)
Total incurred losses and loss adjustment expenses	5,052,749	5,322,009	4,445,589
Payments, current accident year	720,178	729,895	580,537
Payments, prior accident years	3,239,999	2,663,165	2,396,446
Total payments	3,960,177	3,393,060	2,976,983
Effect of foreign currency rate changes on current year activity	(3,934)	(1,532)	(5,468)
Net reserves for losses and loss adjustment expenses of Markel CATCo Re	(159,963)	(162,954)	347,921
Reinsurance Recoverable, Retroactive Reinsurance Transaction	0	(125,067)	0
Net reserves for losses and loss adjustment expenses, end of year	15,512,727	14,662,754	12,953,014
Reinsurance recoverables on unpaid losses, end of year	11,120,367	8,820,567	7,994,884
Gross reserves for losses and loss adjustment expenses, end of year	$ 26,633,094	$ 23,483,321	$ 20,947,898

Unpaid Losses And Loss Adjust_5

Unpaid Losses And Loss Adjustment Expenses (Prior Year Losses and Loss Adjustment Expenses Development by Product Line) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	$ (455.3)	$ (38.6)	$ (167.4)
Insurance [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(451)	(104.7)	(142.9)
Insurance [Member] | Professional liability [Member] | U.S. [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	111.8	56.8
Insurance [Member] | Professional liability [Member] | International
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(152.6)	(102.2)
Insurance [Member] | Professional liability [Member] | Short-Duration Insurance Contracts, Accident Years 2018 and 2019
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years			121
Insurance [Member] | Professional liability [Member] | Short-Duration Insurance Contracts, Accident Years, all other
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years			(91.1)
Insurance [Member] | General liability [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(81.6)
Insurance [Member] | General liability [Member] | U.S. [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years		274
Insurance [Member] | General liability [Member] | International
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years		(36.5)
Insurance [Member] | General liability [Member] | Short-Duration Insurance Contracts, Accident Years 2016 to 2019
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years			61.6
Insurance [Member] | General liability [Member] | Short-Duration Insurance Contracts, Accident Years, all other
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years			(20.5)
Insurance [Member] | Property [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(75)	(95.1)	(48.1)
Insurance [Member] | Marine and energy [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(58.3)	(76.5)
Insurance [Member] | Personal Lines
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years		(42.8)
Insurance [Member] | Workers' compensation [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years		(36.5)	(62.1)
Insurance [Member] | Programs [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(53.9)		(48.3)
Insurance [Member] | Credit and surety [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(51.4)		(31.7)
Insurance [Member] | Other products [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(90)	(45.9)	(23.7)
Reinsurance [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(12.3)	57.1	(26.1)
Reinsurance [Member] | Professional liability [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(17.1)
Reinsurance [Member] | General liability [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years		95.5
Reinsurance [Member] | Property [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(23)	(21.6)	(29.2)
Reinsurance [Member] | Workers' compensation [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(20.3)	(14.9)
Reinsurance [Member] | Premium adjustments
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	(4)	11.4	53.1
Reinsurance [Member] | Credit and surety [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years			(22.9)
Reinsurance [Member] | Public entity
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	34.1	53.7
Reinsurance [Member] | Other products [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	18	(67)	(27.1)
Other [Member] | Other underwriting [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years	$ 8	$ 9	$ 1.6

Unpaid Losses And Loss Adjust_6

Unpaid Losses And Loss Adjustment Expenses (Ultimate Incurred Losses And Cumulative Paid Losses And Allocated Loss Adjustment Expenses, Net Of Reinsurance) (Details)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Claims Development [Line Items]
Total liabilities for unpaid losses and loss adjustment expenses, net of reinsurance	$ 15,087,702,000
Insurance [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	27,539,900,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	16,302,700,000
All outstanding liabilities for unpaid losses and loss adjustment expenses before 2014, net of reinsurance	313,300,000
Total liabilities for unpaid losses and loss adjustment expenses, net of reinsurance	11,550,516,000
Insurance [Member] | 2015 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	1,457,100,000	$ 1,460,000,000	$ 1,440,900,000	$ 1,450,600,000	$ 1,454,700,000	$ 1,486,500,000	$ 1,517,000,000	$ 1,571,000,000	$ 1,693,800,000	$ 1,767,500,000
Total of incurred-but-not-reported liabilities, net of reinsurance	$ 58,000,000
Cumulative number of reported claims	88,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 1,344,700,000	1,327,300,000	1,291,700,000	1,259,200,000	1,208,400,000	1,141,300,000	1,032,900,000	870,200,000	660,000,000	320,700,000
Insurance [Member] | 2016 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	1,718,100,000	1,732,900,000	1,678,400,000	1,667,400,000	1,674,700,000	1,700,300,000	1,753,600,000	1,852,800,000	1,856,300,000
Total of incurred-but-not-reported liabilities, net of reinsurance	$ 77,200,000
Cumulative number of reported claims	100,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 1,529,800,000	1,479,600,000	1,425,500,000	1,350,300,000	1,262,800,000	1,158,200,000	973,700,000	746,200,000	369,800,000
Insurance [Member] | 2017 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	2,152,300,000	2,111,200,000	2,023,900,000	2,004,500,000	1,998,700,000	2,059,300,000	2,176,700,000	2,309,000,000
Total of incurred-but-not-reported liabilities, net of reinsurance	$ 124,600,000
Cumulative number of reported claims	140,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 1,909,500,000	1,839,600,000	1,739,800,000	1,619,200,000	1,462,000,000	1,274,300,000	982,700,000	434,900,000
Insurance [Member] | 2018 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	2,417,100,000	2,331,600,000	2,151,200,000	2,058,800,000	2,199,200,000	2,320,800,000	2,429,000,000
Total of incurred-but-not-reported liabilities, net of reinsurance	$ 177,800,000
Cumulative number of reported claims	193,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 2,017,400,000	1,856,500,000	1,671,600,000	1,494,900,000	1,281,900,000	1,017,400,000	490,700,000
Insurance [Member] | 2019 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	2,526,800,000	2,471,700,000	2,293,700,000	2,239,700,000	2,402,200,000	2,552,400,000
Total of incurred-but-not-reported liabilities, net of reinsurance	$ 206,900,000
Cumulative number of reported claims	228,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 2,104,400,000	1,910,900,000	1,576,400,000	1,262,900,000	991,100,000	524,100,000
Insurance [Member] | 2020 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	2,771,600,000	2,858,500,000	2,914,200,000	2,972,100,000	3,185,100,000
Total of incurred-but-not-reported liabilities, net of reinsurance	$ 434,300,000
Cumulative number of reported claims	183,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 2,033,800,000	1,772,500,000	1,515,700,000	1,148,500,000	568,100,000
Insurance [Member] | 2021 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	2,720,100,000	2,755,400,000	2,907,100,000	3,083,500,000
Total of incurred-but-not-reported liabilities, net of reinsurance	$ 531,000,000
Cumulative number of reported claims	149,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 1,751,100,000	1,357,500,000	985,800,000	473,400,000
Insurance [Member] | 2022 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	3,342,600,000	3,365,500,000	3,746,800,000
Total of incurred-but-not-reported liabilities, net of reinsurance	$ 1,098,300,000
Cumulative number of reported claims	159,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 1,564,100,000	1,059,900,000	484,500,000
Insurance [Member] | 2023 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	3,901,700,000	4,435,900,000
Total of incurred-but-not-reported liabilities, net of reinsurance	$ 1,802,500,000
Cumulative number of reported claims	169,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 1,396,600,000	596,900,000
Insurance [Member] | 2024 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	4,532,500,000
Total of incurred-but-not-reported liabilities, net of reinsurance	$ 3,271,700,000
Cumulative number of reported claims	149,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 651,300,000
Reinsurance [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	7,017,100,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	3,847,700,000
All outstanding liabilities for unpaid losses and loss adjustment expenses before 2014, net of reinsurance	273,300,000
Total liabilities for unpaid losses and loss adjustment expenses, net of reinsurance	3,442,663,000
Reinsurance [Member] | 2015 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	477,700,000	500,000,000	488,200,000	487,800,000	499,900,000	504,800,000	516,000,000	524,600,000	508,800,000	523,000,000
Total of incurred-but-not-reported liabilities, net of reinsurance	56,600,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	388,600,000	375,600,000	359,500,000	342,800,000	323,200,000	298,600,000	251,600,000	201,000,000	130,300,000	$ 63,300,000
Reinsurance [Member] | 2016 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	556,500,000	573,300,000	551,500,000	548,100,000	523,400,000	513,400,000	515,400,000	515,200,000	506,600,000
Total of incurred-but-not-reported liabilities, net of reinsurance	30,100,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	475,700,000	451,600,000	418,000,000	377,900,000	344,400,000	292,700,000	236,400,000	166,700,000	$ 78,600,000
Reinsurance [Member] | 2017 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	931,300,000	931,000,000	919,700,000	907,300,000	934,900,000	933,200,000	927,600,000	894,400,000
Total of incurred-but-not-reported liabilities, net of reinsurance	44,200,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	796,000,000	747,600,000	692,800,000	623,800,000	560,400,000	478,600,000	357,500,000	$ 157,100,000
Reinsurance [Member] | 2018 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	790,100,000	821,000,000	758,100,000	762,500,000	757,400,000	764,900,000	743,000,000
Total of incurred-but-not-reported liabilities, net of reinsurance	82,200,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	613,900,000	543,600,000	474,400,000	404,400,000	334,900,000	235,100,000	$ 86,900,000
Reinsurance [Member] | 2019 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	730,400,000	719,000,000	691,000,000	683,100,000	668,400,000	654,400,000
Total of incurred-but-not-reported liabilities, net of reinsurance	129,100,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	507,700,000	435,600,000	351,800,000	261,300,000	169,100,000	$ 53,200,000
Reinsurance [Member] | 2020 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	765,200,000	762,800,000	741,000,000	730,500,000	678,100,000
Total of incurred-but-not-reported liabilities, net of reinsurance	230,100,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	463,000,000	381,800,000	308,700,000	202,900,000	$ 93,200,000
Reinsurance [Member] | 2021 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	753,900,000	754,700,000	733,600,000	731,900,000
Total of incurred-but-not-reported liabilities, net of reinsurance	303,800,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	361,000,000	281,600,000	187,100,000	$ 79,200,000
Reinsurance [Member] | 2022 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	616,400,000	601,900,000	661,100,000
Total of incurred-but-not-reported liabilities, net of reinsurance	413,400,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	138,400,000	66,600,000	$ 24,100,000
Reinsurance [Member] | 2023 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	665,300,000	658,300,000
Total of incurred-but-not-reported liabilities, net of reinsurance	506,700,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	79,500,000	$ 27,100,000
Reinsurance [Member] | 2024 Accident Year [Member]
Claims Development [Line Items]
Ultimate incurred losses and allocated loss adjustment expenses, net of reinsurance	730,300,000
Total of incurred-but-not-reported liabilities, net of reinsurance	674,300,000
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	$ 23,900,000

Unpaid Losses And Loss Adjust_7

Unpaid Losses And Loss Adjustment Expenses (Average Annual Percentage Payout Of Incurred Losses By Age (in Years), Net Of Reinsurance) (Details)	Dec. 31, 2024
Insurance [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Average annual percentage payout of incurred losses in year 1	18.70%
Average annual percentage payout of incurred losses in year 2	20.90%
Average annual percentage payout of incurred losses in year 3	13.10%
Average annual percentage payout of incurred losses in year 4	10.80%
Average annual percentage payout of incurred losses in year 5	8.50%
Average annual percentage payout of incurred losses in year 6	6.10%
Average annual percentage payout of incurred losses in year 7	4.80%
Average annual percentage payout of incurred losses in year 8	2.90%
Average annual percentage payout of incurred losses in year 9	2.70%
Average annual percentage payout of incurred losses in year 10	1.20%
Reinsurance [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Average annual percentage payout of incurred losses in year 1	9.60%
Average annual percentage payout of incurred losses in year 2	14.40%
Average annual percentage payout of incurred losses in year 3	12.90%
Average annual percentage payout of incurred losses in year 4	10.10%
Average annual percentage payout of incurred losses in year 5	9.50%
Average annual percentage payout of incurred losses in year 6	7.40%
Average annual percentage payout of incurred losses in year 7	6.50%
Average annual percentage payout of incurred losses in year 8	4.90%
Average annual percentage payout of incurred losses in year 9	3.80%
Average annual percentage payout of incurred losses in year 10	2.70%

Unpaid Losses And Loss Adjust_8

Unpaid Losses And Loss Adjustment Expenses (Reconciliation Of Net Incurred And Paid Loss Development Tables, By Segment, To The Liability For Losses And Loss Adjustment Expenses In The Consolidated Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Short-Duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for unpaid losses and loss adjustment expenses, net of reinsurance	$ 15,087,702
Reinsurance recoverable on unpaid losses	11,120,367
Unallocated loss adjustment expenses	425,025
Total gross liability for unpaid losses and loss adjustment expenses	26,633,094	$ 23,483,321	$ 20,947,898	$ 18,178,894
Market CATCo Re
Short-Duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for unpaid losses and loss adjustment expenses, net of reinsurance	25,005
Insurance [Member]
Short-Duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for unpaid losses and loss adjustment expenses, net of reinsurance	11,550,516
Reinsurance recoverable on unpaid losses	4,129,856
Total gross liability for unpaid losses and loss adjustment expenses	16,073,355	14,221,258
Reinsurance [Member]
Short-Duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for unpaid losses and loss adjustment expenses, net of reinsurance	3,442,663
Reinsurance recoverable on unpaid losses	397,810
Total gross liability for unpaid losses and loss adjustment expenses	3,870,059	3,726,472
Other underwriting [Member]
Short-Duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for unpaid losses and loss adjustment expenses, net of reinsurance	62,903
Reinsurance recoverable on unpaid losses	84,079
Total gross liability for unpaid losses and loss adjustment expenses	149,522	165,071
Fronting [Member]
Short-Duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for unpaid losses and loss adjustment expenses, net of reinsurance	6,615
Reinsurance recoverable on unpaid losses	6,508,622
Total gross liability for unpaid losses and loss adjustment expenses	$ 6,515,153	$ 5,185,553

Reinsurance (Narrative) (Detail

Reinsurance (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Reinsurance Disclosures [Line Items]
Percentage of ceded earned premiums to gross earned premiums	44%	39%	38%
Percentage of assumed earned premiums to net earned premiums	38%	31%	30%
Underwriting [Member]
Reinsurance Disclosures [Line Items]
Reinsurance recoverables	$ (1,917,318)	$ (1,496,265)	$ (834,648)
Reinsurance Recoverables, Gross	$ 5,000,000	$ 4,000,000
Underwriting [Member] | Ten Largest Reinsurers [Member]
Reinsurance Disclosures [Line Items]
Recoverable balances as a percentage of the total balance	63%	65%
Underwriting [Member] | RenaissanceRe
Reinsurance Disclosures [Line Items]
Recoverable balances as a percentage of the total balance	19%
Fronting [Member]
Reinsurance Disclosures [Line Items]
Reinsurance recoverables	$ 3,500,000	$ 2,500,000	$ 3,000,000
Program Services [Member]
Reinsurance Disclosures [Line Items]
Reinsurance Recoverables, Gross	$ 6,000,000	$ 4,900,000
Program Services [Member] | Ten Largest Reinsurers [Member]
Reinsurance Disclosures [Line Items]
Recoverable balances as a percentage of the total balance	55%	56%
Program Services [Member] | Knight Insurance Company
Reinsurance Disclosures [Line Items]
Recoverable balances as a percentage of the total balance	9%
ILS fronting [Member] | Nephila Reinsurers [Member]
Reinsurance Disclosures [Line Items]
Recoverable balances as a percentage of the total balance	100%

Reinsurance (Effect Of Reinsura

Reinsurance (Effect Of Reinsurance And Retrocessional Reinsurance On Premiums Written And Earned) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Effects of Reinsurance [Line Items]
Direct premiums written	$ 12,094,040	$ 11,306,483	$ 10,729,950
Direct premiums earned	11,855,424	10,999,889	10,068,570
Assumed premiums written	3,400,591	2,695,754	2,471,732
Assumed premiums earned	3,188,007	2,554,030	2,246,805
Ceded premiums written	(7,198,456)	(5,604,662)	(4,998,292)
Ceded premiums earned	(6,611,019)	(5,258,440)	(4,727,583)
Net premiums written	8,296,175	8,397,575	8,203,390
Net premiums earned	8,432,412	8,295,479	7,587,792
Underwriting [Member]
Effects of Reinsurance [Line Items]
Direct premiums written	8,860,015	8,657,266	8,085,812
Direct premiums earned	8,801,477	8,363,710	7,379,766
Assumed premiums written	1,691,858	1,620,366	1,761,726
Assumed premiums earned	1,628,408	1,616,630	1,589,920
Ceded premiums written	(2,252,122)	(1,878,844)	(1,640,165)
Ceded premiums earned	(1,993,895)	(1,683,648)	(1,378,191)
Net premiums written	8,299,751	8,398,788	8,207,373
Net premiums earned	8,435,990	8,296,692	7,591,495
Fronting [Member]
Effects of Reinsurance [Line Items]
Direct premiums written	3,234,025	2,649,217	2,644,138
Direct premiums earned	3,053,947	2,636,179	2,688,804
Assumed premiums written	1,708,733	1,075,388	710,006
Assumed premiums earned	1,559,599	937,400	656,885
Ceded premiums written	(4,946,334)	(3,725,818)	(3,358,127)
Ceded premiums earned	(4,617,124)	(3,574,792)	(3,349,392)
Net premiums written	(3,576)	(1,213)	(3,983)
Net premiums earned	$ (3,578)	$ (1,213)	$ (3,703)

Reinsurance Reinsurance (Effect

Reinsurance Reinsurance (Effect of Reinsurance and Retrocessional Reinsurance on Incurred Losses and Loss Adjustment Expenses) (Details) - Underwriting Operations [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Effects of Reinsurance [Line Items]
Gross losses and loss adjustment expenses	$ 6,970,871	$ 6,817,630	$ 5,281,424
Ceded losses and loss adjustment expenses	(1,917,318)	(1,496,265)	(834,648)
Net losses and loss adjustment expenses	$ 5,053,553	$ 5,321,365	$ 4,446,776

Life and Annuity Benefits (Sche

Life and Annuity Benefits (Schedule of Liability for Future Policyholder Benefits) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Liability for Future Policy Benefit, Activity [Line Items]
Liability for future policy holder benefits	$ 491,370	$ 557,763	$ 554,366	$ 821,632
Deferred profit liability	51,482	52,287
Other	40,421	39,004
Life and annuity benefits	$ 583,273	$ 649,054

Life And Annuity Benefits (Sc_2

Life And Annuity Benefits (Schedule of Liability for Future Policy Benefit, Activity) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Undiscounted liability for future policy benefits	$ 737,575	$ 824,642	$ 861,264
Liability for future policyholder benefits, beginning of year	557,763	554,366	821,632
Liability for future policyholder benefits at original discount rate, beginning of year	642,877	667,761	745,313
Effect of changes in cash flow assumptions		0	0	$ 0
Effect of actual variances from expected experience		(4,745)	(5,890)	(3,859)
Adjusted liability for future policyholder benefits, beginning of year		638,132	661,871	$ 741,454
Interest accretion	13,996	14,889	15,625
Benefit payments	(49,200)	(52,588)	(53,232)
Effect of foreign currency rate changes	(26,126)	18,705	(36,086)
Liability for future policyholder benefits at original discount rate, end of year	576,802	642,877	667,761
Cumulative effect of changes in discount rate assumptions	(85,432)	(85,114)	(113,395)
Liability for future policyholder benefits, end of year	$ 491,370	$ 557,763	$ 554,366

Life And Annuity Benefits (Sc_3

Life And Annuity Benefits (Schedule of Additional Details of Liability for Future Policyholder Benefits, Life and Annuity) (Details)	Dec. 31, 2024 Rate	Dec. 31, 2023 Rate
Interest accretion rate	2.30%	2.30%
Current discount rate	4%	3.80%
Weighted-average liability duration	8 years 3 months 18 days	8 years 7 months 6 days

Senior Long-Term Debt And Oth_3

Senior Long-Term Debt And Other Debt (Narrative) (Details) - USD ($) $ in Thousands		12 Months Ended
	May 15, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Senior long-term debt and other debt		$ 4,330,341	$ 3,779,796
Senior long-term debt and other debt, estimated fair value		$ 3,800,000	3,400,000
Line of credit facility, initiation date		Jun. 23, 2023
Line of credit facility, expiration date		Jun. 23, 2028
Interest on senior long-term debt and other debt		$ 197,400	187,800	$ 197,300
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, increase (decrease), net		$ 200,000
Line of credit facility, unused capacity, commitment fee percentage		0.20%
Borrowings outstanding under the facility		$ 0	0
Revolving Credit Facility [Member] | Markel Ventures [Member]
Debt Instrument [Line Items]
Line of credit facility, capacity available		692,000
Borrowings outstanding under the facility		150,000	169,500
Revolving Credit Facility [Member] | Secured Letters Of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, capacity available		200,000
Previous line of credit facility
Debt Instrument [Line Items]
Line of credit facility, capacity available		300,000
Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Senior long-term debt and other debt		4,032,959
Other Debt [Member]
Debt Instrument [Line Items]
Senior long-term debt and other debt		297,382	340,597
Other Debt [Member] | Markel Ventures [Member]
Debt Instrument [Line Items]
Senior long-term debt and other debt		$ 297,400	339,000
7.35% Unsecured Senior Notes Due August 15, 2034 [Member] | Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		7.35%
3.625% Unsecured Senior Notes Due March 30, 2023 [Member] | Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 250,000
Debt instrument, interest rate			3.625%
6.0% Unsecured Senior Notes due May 16 2054
Debt Instrument [Line Items]
Net proceeds from issuance of unsecured senior notes	$ 592,600
6.0% Unsecured Senior Notes due May 16 2054 | Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 600,000
Debt instrument, interest rate	6%	6%

Senior Long-Term Debt And Oth_4

Senior Long-Term Debt And Other Debt (Summary Of Senior Long-Term Debt And Other Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	May 15, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Senior long-term debt and other debt	$ 4,330,341		$ 3,779,796
Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Senior long-term debt and other debt	4,032,959
Unsecured Senior Notes [Member] | 3.50% Unsecured Senior Notes Due November 1, 2027 [Member]
Debt Instrument [Line Items]
Unsecured senior notes	$ 299,236		298,869
Debt instrument, interest rate	3.50%
Debt Instrument, Unamortized Discount	$ 592		876
Unsecured Senior Notes [Member] | 3.35% Unsecured Senior Notes Due September 17, 2029 [Member]
Debt Instrument [Line Items]
Unsecured senior notes	$ 298,590		298,294
Debt instrument, interest rate	3.35%
Debt Instrument, Unamortized Discount	$ 1,174		1,421
Unsecured Senior Notes [Member] | 7.35% Unsecured Senior Notes Due August 15, 2034 [Member]
Debt Instrument [Line Items]
Unsecured senior notes	$ 129,148		129,076
Debt instrument, interest rate	7.35%
Debt Instrument, Unamortized Discount	$ 663		731
Unsecured Senior Notes [Member] | 5.0% Unsecured Senior Notes Due March 30, 2043 [Member]
Debt Instrument [Line Items]
Unsecured senior notes	$ 245,687		245,451
Debt instrument, interest rate	5%
Debt Instrument, Unamortized Discount	$ 4,087		4,311
Unsecured Senior Notes [Member] | 5.0% Unsecured Senior Notes Due April 5, 2046 [Member]
Debt Instrument [Line Items]
Unsecured senior notes	$ 494,135		493,860
Debt instrument, interest rate	5%
Debt Instrument, Unamortized Discount	$ 5,202		5,445
Unsecured Senior Notes [Member] | 4.30% Unsecured Senior Notes Due November 1, 2047 [Member]
Debt Instrument [Line Items]
Unsecured senior notes	$ 296,049		295,870
Debt instrument, interest rate	4.30%
Debt Instrument, Unamortized Discount	$ 3,364		3,516
Unsecured Senior Notes [Member] | 5.0% Unsecured Senior Notes Due May 20, 2049 [Member] [Domain]
Debt Instrument [Line Items]
Unsecured senior notes	$ 592,538		592,233
Debt instrument, interest rate	5%
Debt Instrument, Unamortized Discount	$ 6,378		6,639
Unsecured Senior Notes [Member] | 4.15% Unsecured Senior Notes Due September 17 2050 [Member]
Debt Instrument [Line Items]
Unsecured senior notes	$ 494,749		494,546
Debt instrument, interest rate	4.15%
Debt Instrument, Unamortized Discount	$ 4,563		4,740
Unsecured Senior Notes [Member] | 3.45% Unsecured Senior Notes due May 7 2052
Debt Instrument [Line Items]
Unsecured senior notes	$ 591,316		591,000
Debt instrument, interest rate	3.45%
Debt Instrument, Unamortized Discount	$ 7,626		7,904
Unsecured Senior Notes [Member] | 6.0% Unsecured Senior Notes due May 16 2054
Debt Instrument [Line Items]
Unsecured senior notes	$ 591,511		0
Debt instrument, interest rate	6%	6%
Debt Instrument, Unamortized Discount	$ 7,240		0
Other Debt [Member]
Debt Instrument [Line Items]
Senior long-term debt and other debt	$ 297,382		$ 340,597
Other Debt [Member] | Other Debt [Member] | Weighted Average
Debt Instrument [Line Items]
Debt instrument, interest rate	5.40%		5%

Senior Long-Term Debt And Oth_5

Senior Long-Term Debt And Other Debt (Summary Of Future Principal Payments Due At Maturity On Senior Long-Term Debt And Other Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
2025	$ 41,843
2026	41,902
2027	458,376
2028	16,724
2029	315,182
2030 and thereafter	3,505,751
Total principal payments	4,379,778
Net unamortized discount	(40,889)
Net unamortized debt issuance costs	(8,548)
Senior long-term debt and other debt	4,330,341	$ 3,779,796
Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
2025	0
2026	0
2027	300,000
2028	0
2029	300,000
2030 and thereafter	3,479,846
Total principal payments	4,079,846
Net unamortized discount	(40,889)
Net unamortized debt issuance costs	(5,998)
Senior long-term debt and other debt	4,032,959
Other Debt [Member]
Debt Instrument [Line Items]
2025	41,843
2026	41,902
2027	158,376
2028	16,724
2029	15,182
2030 and thereafter	25,905
Total principal payments	299,932
Net unamortized discount	0
Net unamortized debt issuance costs	(2,550)
Senior long-term debt and other debt	$ 297,382	$ 340,597

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Line Items]
Income tax payments	$ 382,500,000	$ 280,700,000	$ 251,500,000
Income taxes payable	40,300,000	29,400,000
Income taxes receivable	13,300,000	300,000
Unrecognized tax benefits	0
Deferred tax liability, net	1,541,030,000	1,170,399,000
Tax credit carryforwards	45,481,000	25,396,000
Gross deferred tax assets	840,601,000	801,495,000
Valuation allowance	(33,292,000)	(13,916,000)
Estimated gross deferred tax assets including net operating losses realized through generating taxable income or reversal of existing temporary differences attributable to gross deferred tax liabilities	$ 807,300,000
Income Tax Examination, Year under Examination	2017
Earliest Tax Year [Member]
Income Tax Disclosure [Line Items]
Tax credit, expiration date	Dec. 31, 2034
U.S. State Operations
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 28,900,000
Certain Foreign Operations [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	7,700,000
Other Liabilities [Member]
Income Tax Disclosure [Line Items]
Deferred tax liability, net	1,600,000,000	1,200,000,000
Other Assets [Member]
Income Tax Disclosure [Line Items]
Net deferred tax assets	$ 40,000,000	$ 23,500,000

Income Taxes (Components Of Inc

Income Taxes (Components Of Income Before Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
U.S. operations	$ 2,428,694	$ 1,711,849	$ (109,311)
Foreign operations	1,209,006	941,857	(42,255)
Income (Loss) Before Income Taxes	$ 3,637,700	$ 2,653,706	$ (151,566)

Income Taxes (Components Of I_2

Income Taxes (Components Of Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
U.S., current	$ 271,801	$ 249,149	$ 222,074
Foreign, current	123,933	69,669	12,042
Total current tax expense	395,734	318,818	234,116
U.S., deferred	399,169	250,041	(301,423)
Foreign, deferred	(4,609)	(16,243)	19,098
Total deferred tax expense (benefit)	394,560	233,798	(282,325)
Income tax expense (benefit)	$ 790,294	$ 552,616	$ (48,209)

Income Taxes (Reconciliations O

Income Taxes (Reconciliations Of United States Corporate Income Tax Rate To Effective Tax Rate On Income Before Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
U.S. corporate tax rate	21%	21%	21%
State income taxes, net of U.S. federal income tax benefit, percent	1.10%	1%	(2.20%)
Tax-exempt investment income, percent	(0.40%)	(0.60%)	10.60%
Foreign operations, percent	0.30%	0.40%	(3.50%)
Impairment of goodwill, percent	0%	0%	(11.10%)
Markel CATCo Re income not subject to tax, percent	(0.30%)	(0.60%)	12.50%
Other, percent	0%	(0.40%)	4.50%
Effective tax rate	21.70%	20.80%	31.80%
Income taxes at U.S. corporate tax rate	$ 763,917	$ 557,278	$ (31,829)
State income taxes, net of U.S. federal income tax benefit	39,770	27,007	3,369
Tax-exempt investment income	(14,830)	(15,328)	(16,063)
Foreign operations	12,985	10,854	5,335
Impairment of goodwill	0	0	16,800
Markel CATCo Re income not subject to tax	(12,201)	(15,013)	(18,871)
Other	653	(12,182)	(6,950)
Income tax expense (benefit)	$ 790,294	$ 552,616	$ (48,209)

Income Taxes (Components Of Dom

Income Taxes (Components Of Domestic And Foreign Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Unpaid losses and loss adjustment expenses	$ 233,583	$ 216,863
Lease liabilities	172,131	161,350
Unearned premiums	164,485	168,172
Accrued incentive compensation	51,943	52,853
Tax credit carryforwards	45,481	25,396
Net operating loss carryforwards	37,168	43,439
Life and annuity benefits	29,143	39,729
Other differences between financial reporting and tax bases	106,667	93,693
Total gross deferred tax assets	840,601	801,495
Less valuation allowance	(33,292)	(13,916)
Total gross deferred tax assets, net of allowance	807,309	787,579
Investments	1,566,540	1,196,717
Deferred policy acquisition costs	173,742	176,382
Goodwill and other intangible assets	170,941	175,767
Right-of-use lease assets	162,628	152,939
Property, plant and equipment	160,615	152,149
Other differences between financial reporting and tax bases	113,873	104,024
Total gross deferred tax liabilities	2,348,339	1,957,978
Deferred tax liability, net	$ 1,541,030	$ 1,170,399

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Postemployment Benefits [Abstract]
Expenses relating to defined contribution plans	$ 72.4	$ 65.4	$ 57.9
Projected benefit plan obligations of Terra Nova Pension Plan	105.4	117.3
Fair value of Terra Nova Pension Plan assets	$ 168.8	$ 184.6

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Variable Interest Entity [Line Items]
Cash funding used to purchase Markel CATCo Funds' interests in Markel CATCo Re					$ 45,100
Additional payments made, net of insurance proceeds, to investors by Markel					$ 101,900
Returned capital from Markel CATCo Re	$ 24,900
Investment in Markel CATCo Re		$ 20,100	$ 20,100
Percentage of Markel CATCo Re net equity by the Company		52%	23%
Prior Year Claims and Claims Adjustment Expense		$ 455,300	$ 38,600	$ 167,400
Tail risk cover in proposed CATCo transaction		95,000
Noncontrolling Interests [Member]
Variable Interest Entity [Line Items]
Redemption of Markel CATCo Re noncontrolling interests		(117,227)	(62,646)	(22,261)
Market CATCo Re
Variable Interest Entity [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (58,100)	$ (71,500)	$ (89,900)

Variable Interest Entities (Det

Variable Interest Entities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 3,692,667	$ 3,747,060
Restricted cash and cash equivalents	499,581	584,974
Assets	61,897,982	55,045,710
Unpaid losses and loss adjustment expenses	26,633,094	23,483,321	$ 20,947,898	$ 18,178,894
Other liabilities	4,383,444	3,927,498
Total Liabilities	44,429,009	39,519,817
Shareholders' equity	16,915,898	14,983,928
Noncontrolling interests	13,041	72,280
Total Equity	16,928,939	15,056,208
Total Liabilities and Equity	61,897,982	55,045,710
Market CATCo Re
Variable Interest Entity [Line Items]
Cash and cash equivalents	34,497	91,301
Restricted cash and cash equivalents	28,701	173,800
Other assets and receivables due from cedents	329	19,292
Assets	63,527	284,393
Unpaid losses and loss adjustment expenses	25,005	184,967
Other liabilities	66	1,842
Total Liabilities	25,071	186,809
Shareholders' equity	21,139	21,139
Noncontrolling interests	17,317	76,445
Total Equity	38,456	97,584
Total Liabilities and Equity	$ 63,527	$ 284,393

Fund Management Related Party D

Fund Management Related Party Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Services and other revenues	$ 2,824,977	$ 2,704,512	$ 2,809,425
Insurance-linked Securities Operations [Member] | Unconsolidated entities managed by Nephila [Member]
Related Party Transaction [Line Items]
Services and other revenues	$ 94,600	$ 97,600	$ 74,300

Fronting Related Party Transact

Fronting Related Party Transactions (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Gross written premiums	$ 15,494,631	$ 14,002,237	$ 13,201,682
Ceded written premium	7,198,456	5,604,662	4,998,292
Fronting fees	187,480	154,838	147,612
Reinsurance recoverables	11,604,844	9,235,501
Nephila Reinsurers [Member]
Related Party Transaction [Line Items]
Reinsurance recoverables	968,900	794,300
Fronting [Member] | Nephila Reinsurers [Member]
Related Party Transaction [Line Items]
Gross written premiums	1,300,000	1,100,000	1,000,000
Ceded written premium	1,300,000	1,100,000	1,000,000
Fronting fees	39,400	$ 34,700	$ 37,000
Industry Loss Warranties (ILW) Program [Member] | Nephila Reinsurers [Member]
Related Party Transaction [Line Items]
Gross written premiums	168,000
Ceded written premium	$ 168,000

Hagerty Related Party Disclosur

Hagerty Related Party Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Gross written premiums	$ 15,494,631	$ 14,002,237	$ 13,201,682
Ceded written premium	7,198,456	5,604,662	4,998,292
Reinsurance recoverables	11,604,844	9,235,501
Hagerty [Member]
Related Party Transaction [Line Items]
Gross written premiums	922,657	805,673	689,670
Ceded written premium	708,147	616,491	$ 456,637
Reinsurance recoverables	$ 308,800	$ 214,800

Shareholders' Equity (Narrative

Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	May 27, 2020	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuer's Redemption Option, Period to Redeem After a Redemption Event	90 days
Preferred Stock, Redemption Price Per Share	$ 1,000
Earnings Per Share [Line Items]
Preferred stock, shares authorized		10,000,000
Preferred stock dividends		$ 36	$ 36
Preferred stock dividends, cash		$ 36	$ 36
Preferred Stock, Dividends Per Share, Declared		$ 60	$ 60
Preferred Stock, Dividends, Per Share, Cash Paid		60	$ 60
Rating Agency Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Redemption Price Per Share	1,020
Regulatory Capital Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Redemption Price Per Share	$ 1,000
Series A Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Dividend Rate, Reset Percentage	5.662%
Preferred Stock, Reset Period	5 years
Preferred Stock, Liquidation Preference Per Share	$ 1,000
Earnings Per Share [Line Items]
Preferred Stock, No Par Value		$ 0
Preferred stock, shares issued		600,000	600,000
Preferred stock, shares outstanding		600,000	600,000
Preferred Stock, Dividend Rate, Percentage	6%

Shareholders' Equity (Schedule

Shareholders' Equity (Schedule of Common Stock Outstanding Roll Forward) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Class of Stock [Line Items]
Common stock, shares authorized	50,000,000
Common stock, no par value	$ 0
Common Stock [Member]
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
Stock Repurchased During Period, Shares	(370,034)	(321,760)
Shares, Issued, Ending Balance	12,790,117	13,131,672
Shares, Outstanding, Ending Balance	12,790,117	13,131,672
Common Stock [Member] | Common Stock [Member]
Class of Stock [Line Items]
Issuance of common stock, shares	28,479	30,740

Shareholders' Equity (Schedul_2

Shareholders' Equity (Schedule Of Net Income Per Common Share) (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2024		Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Line Items]
Net income (loss) to common shareholders		$ 2,711,022		$ 1,960,060	$ (252,277)
Adjustment of redeemable noncontrolling interests		(111,700)		6,212	(69,896)
Adjusted net income (loss) to common shareholders		$ 2,599,322		$ 1,966,272	$ (322,173)
Basic common shares outstanding		13,017,000		13,347,000	13,580,000
Diluted common shares outstanding		13,041,000		13,378,000	13,580,000
Basic net income (loss) per common share		$ 199.69		$ 147.32	$ (23.72)
Diluted net income per common share		$ 199.32		$ 146.98	$ (23.72)	[1]
Number of shares available for future awards	[2]	284,049
Restricted Stock Units (RSUs) [Member]
Earnings Per Share [Line Items]
Dilutive potential common shares from restricted stock units and restricted stock		24,000	[2]	31,000	0	[1]
Potential incremental common shares attributable to share-based payment arrangements	[1]				33,000
[1] The impact of 33 thousand shares from restricted stock units and restricted stock was excluded from the computation of diluted net loss per common share for the year ended December 31, 2022 because the effect would have been anti-dilutive. The Company has issued grants and awards of restricted stock units to employees as performance, retention or hiring incentives, as well as awards of restricted stock to non-employee directors, under its equity incentive compensation plan. At December 31, 2024, there were 284,049 shares available for future awards under the Company's equity incentive compensation plan.

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Change In Accumulated Other Comprehensive Income By Component, Net Of Noncontrolling Interests) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	$ (478,210)
Income tax (expense) benefit	(790,294)	$ (552,616)	$ 48,209
Accumulated other comprehensive income (loss), ending balance	(617,082)	(478,210)
Unrealized Gains (Losses) On Available-For-Sale Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(459,373)	(766,276)	388,554
Total other comprehensive income (loss) before income taxes	(165,423)	390,558	(1,463,876)
Income tax (expense) benefit	35,128	(83,655)	309,046
Total other comprehensive income (loss)	(130,295)	306,903	(1,154,830)
Accumulated other comprehensive income (loss), ending balance	(589,668)	(459,373)	(766,276)
Accumulated Life and Annuity Discount Rate Assumption Adjustment Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	67,240	89,583	(60,291)
Total other comprehensive income (loss) before income taxes	319	(28,281)	189,714
Income tax (expense) benefit	(67)	5,938	(39,840)
Total other comprehensive income (loss)	252	(22,343)	149,874
Accumulated other comprehensive income (loss), ending balance	67,492	67,240	89,583
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(61,257)	(65,907)	(56,631)
Total other comprehensive income (loss) before income taxes	(3,883)	4,650	(9,677)
Income tax (expense) benefit	0	0	401
Total other comprehensive income (loss)	(3,883)	4,650	(9,276)
Accumulated other comprehensive income (loss), ending balance	(65,140)	(61,257)	(65,907)
Net Actuarial Pension Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(24,820)	(24,894)	(49,624)
Total other comprehensive income (loss) before income taxes	(6,600)	94	31,222
Income tax (expense) benefit	1,654	(20)	(6,492)
Total other comprehensive income (loss)	(4,946)	74	24,730
Accumulated other comprehensive income (loss), ending balance	(29,766)	(24,820)	(24,894)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(478,210)	(767,494)	222,008
Total other comprehensive income (loss) before income taxes	(175,587)	367,021	(1,252,617)
Income tax (expense) benefit	36,715	(77,737)	263,115
Total other comprehensive income (loss)	(138,872)	289,284	(989,502)
Accumulated other comprehensive income (loss), ending balance	$ (617,082)	$ (478,210)	$ (767,494)

Statutory Financial Informati_3

Statutory Financial Information (Narrative) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Statutory Accounting Practices [Line Items]
Amount of cash and investments held as funds at Lloyd's	$ 913.7
Parent Company [Member]
Statutory Accounting Practices [Line Items]
Amount of cash and investments held as funds at Lloyd's	272.4
United States [Member]
Statutory Accounting Practices [Line Items]
Amount available for dividend payment	672.9
Bermuda [Member]
Statutory Accounting Practices [Line Items]
Amount available for dividend payment	$ 603.6

Statutory Financial Informati_4

Statutory Financial Information (Actual Statutory Capital And Surplus) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
United States [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	$ 6,764,770	$ 5,958,801
United Kingdom [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	1,001,574	977,604
Bermuda [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	2,414,364	2,353,058
Germany [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	$ 171,581	$ 166,403

Statutory Financial Informati_5

Statutory Financial Information (Statutory Net Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
United States [Member]
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	$ 500,860	$ 196,952	$ 689,341
United Kingdom [Member]
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	62,084	116,436	35,719
Bermuda [Member]
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	614,056	484,417	(144,239)
Germany [Member]
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	$ 10,075	$ 5,543	$ (2,471)

Markel Group (Parent Company _3

Markel Group (Parent Company Only) Financial Information (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Revolving Credit Facility [Member]
Condensed Financial Statements, Captions [Line Items]
Borrowings outstanding under the facility	$ 0	$ 0
Markel Ventures [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Guaranteed by Parent	788	738
Markel Ventures [Member] | Revolving Credit Facility [Member]
Condensed Financial Statements, Captions [Line Items]
Borrowings outstanding under the facility	$ 150	$ 169.5

Markel Group (Parent Company _4

Markel Group (Parent Company Only) Financial Information (Schedule Of Condensed Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Condensed Financial Statements, Captions [Line Items]
Fixed maturity securities, available-for-sale (amortized cost of $130,983 in 2024 and $139,766 in 2023)	$ 15,745,539	$ 14,372,732
Equity securities (cost of $1,084,814 in 2024 and $1,089,332 in 2023)	11,784,521	9,577,871
Short-term investments, available-for-sale (estimated fair value approximates cost)	2,524,910	2,571,382
Investments	30,054,970	26,521,985
Cash and cash equivalents	3,692,667	3,747,060
Restricted cash and cash equivalents	499,581	584,974
Other assets	4,400,711	3,990,864
Total Assets	61,897,982	55,045,710
Senior long-term debt	4,330,341	3,779,796
Deferred tax liability, net	1,541,030	1,170,399
Other liabilities	4,383,444	3,927,498
Total Liabilities	44,429,009	39,519,817
Preferred stock	591,891	591,891
Common stock	3,560,633	3,517,146
Retained earnings	13,380,456	11,353,101
Accumulated other comprehensive loss	(617,082)	(478,210)
Shareholders' equity	16,915,898	14,983,928
Total Liabilities and Equity	61,897,982	55,045,710
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Fixed maturity securities, available-for-sale (amortized cost of $130,983 in 2024 and $139,766 in 2023)	123,053	131,544
Equity securities (cost of $1,084,814 in 2024 and $1,089,332 in 2023)	2,071,110	1,731,839
Short-term investments, available-for-sale (estimated fair value approximates cost)	1,410,830	1,032,118
Investments	3,604,993	2,895,501
Cash and cash equivalents	701,289	635,047
Restricted cash and cash equivalents	20,013	15,908
Investments in consolidated subsidiaries	16,699,125	14,928,756
Other assets	450,327	441,977
Total Assets	21,475,747	18,917,189
Senior long-term debt	4,032,960	3,439,197
Income taxes payable	179,381	213,770
Deferred tax liability, net	274,661	201,140
Other liabilities	72,847	79,154
Total Liabilities	4,559,849	3,933,261
Preferred stock	591,891	591,891
Common stock	3,560,633	3,517,146
Retained earnings	13,380,456	11,353,101
Accumulated other comprehensive loss	(617,082)	(478,210)
Shareholders' equity	16,915,898	14,983,928
Total Liabilities and Equity	$ 21,475,747	$ 18,917,189

Markel Group (Parent Company _5

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

Markel Group (Parent Company _6

Markel Group (Parent Company Only) Financial Information (Schedule Of Condensed Statements Of Income And Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Financial Statements, Captions [Line Items]
Net investment income	$ 920,496	$ 734,532	$ 446,755
Change in fair value of equity securities	1,802,796	1,566,231	(1,554,750)
Net investment gains (losses)	1,807,219	1,524,054	(1,595,733)
Gain on disposition of subsidiary	0	18,965	225,832
Other	7,211	42,733	33,970
Total operating revenues	16,620,763	15,803,630	11,675,335
Services and other expenses	2,424,372	2,310,769	2,306,985
Interest expense	204,300	185,077	196,062
Net foreign exchange losses (gains)	(129,438)	90,045	(137,832)
Total operating expenses	12,908,201	12,874,802	11,768,671
Income tax (expense) benefit	(790,294)	(552,616)	48,209
Net Income (Loss) to Shareholders	2,747,022	1,996,060	(216,277)
Preferred stock dividends	(36,000)	(36,000)	(36,000)
Net Income (Loss) to Common Shareholders	2,711,022	1,960,060	(252,277)
Net holding gains (losses) arising during the period	(148,302)	278,363	(1,199,736)
Reclassification adjustments for net gains (losses) included in net income (loss)	18,007	28,540	44,906
Change in net unrealized gains (losses) on available-for-sale investments, net of taxes	(130,295)	306,903	(1,154,830)
Total Other Comprehensive Income (Loss)	(138,754)	289,338	(989,485)
Comprehensive Income (Loss) to Shareholders	2,608,150	2,285,344	(1,205,779)
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net investment income	86,583	92,080	34,781
Dividends on common stock of consolidated subsidiaries	575,008	310,000	278,557
Net realized investment gains (losses)	16,718	(515)	7,620
Change in fair value of equity securities	342,623	275,048	(397,906)
Net investment gains (losses)	359,341	274,533	(390,286)
Gain on disposition of subsidiary	0	0	107,293
Other	31,132	(28,718)	(29,487)
Total operating revenues	1,052,064	647,895	858
Services and other expenses	12,061	19,716	111,848
Interest expense	179,626	156,953	172,125
Net foreign exchange losses (gains)	(36,907)	9,038	(13,143)
Total operating expenses	154,780	185,707	270,830
Income (Loss) Before Equity in Undistributed Earnings (Losses) of Consolidated Subsidiaries and Income Taxes	897,284	462,188	(269,972)
Equity in undistributed earnings (losses) of consolidated subsidiaries	1,941,339	1,580,347	(72,125)
Income tax (expense) benefit	(91,601)	(46,475)	125,820
Net Income (Loss) to Shareholders	2,747,022	1,996,060	(216,277)
Preferred stock dividends	(36,000)	(36,000)	(36,000)
Net Income (Loss) to Common Shareholders	2,711,022	1,960,060	(252,277)
Net holding gains (losses) arising during the period	109	1,453	(24,465)
Consolidated subsidiaries' net holding gains (losses) arising during the period	(148,411)	276,910	(1,175,271)
Reclassification adjustments for net gains (losses) included in net income (loss)	365	(92)	1,965
Consolidated subsidiaries' reclassification adjustments for net losses included in net income to shareholders	17,642	28,632	42,941
Change in net unrealized gains (losses) on available-for-sale investments, net of taxes	(130,295)	306,903	(1,154,830)
Consolidated Subsidiaries' Change in discount rate for life and annuity benefits, net of taxes	252	(22,343)	149,874
Consolidated subsidiaries' change in foreign currency translation adjustments, net of taxes	(3,883)	4,650	(9,276)
Consolidated subsidiaries' change in net actuarial pension loss, net of taxes	(4,946)	74	24,730
Total Other Comprehensive Income (Loss)	(138,872)	289,284	(989,502)
Comprehensive Income (Loss) to Shareholders	$ 2,608,150	$ 2,285,344	$ (1,205,779)

Markel Group (Parent Company _7

Markel Group (Parent Company Only) Financial Information (Schedule Of Condensed Statements Of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Financial Statements, Captions [Line Items]
Net income (loss) to shareholders	$ 2,747,022	$ 1,996,060	$ (216,277)
Net Cash Provided By Operating Activities	2,594,006	2,786,807	2,709,442
Proceeds from sales, maturities, calls and prepayments of fixed maturity securities	2,068,755	2,126,586	1,152,335
Cost of fixed maturity securities purchased	(3,588,989)	(4,302,864)	(2,112,066)
Proceeds from sales of equity securities	177,254	298,582	242,010
Cost of equity securities purchased	(571,096)	(638,306)	(442,991)
Net change in short-term investments	151,972	202,930	(846,019)
Cost of equity method investments	(205,937)	(192,715)	(20,051)
Other	32,167	23,081	28,345
Net Cash Used By Investing Activities	(2,398,618)	(2,703,607)	(1,670,204)
Repayment and retirement of senior long-term debt	(896,749)	(949,636)	(1,255,005)
Additions to senior long-term debt	1,434,205	624,972	1,034,052
Repurchases of common stock	(572,728)	(445,479)	(290,796)
Dividends paid on preferred stock	(36,000)	(36,000)	(36,000)
Other	(8,886)	(12,227)	(32,307)
Net Cash Used By Financing Activities	(297,878)	(999,716)	(595,311)
Increase (decrease) in cash, cash equivalents, restricted cash and restricted cash equivalents	(139,786)	(889,479)	340,566
Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of year	4,332,034	5,221,513	4,880,947
CASH, CASH EQUIVALENTS, RESTRICTED CASH AND RESTRICTED CASH EQUIVALENTS AT END OF YEAR	4,192,248	4,332,034	5,221,513
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss) to shareholders	2,747,022	1,996,060	(216,277)
Adjustments to reconcile net income (loss) to shareholders to net cash provided by operating activities	(2,183,635)	(1,664,382)	489,413
Net Cash Provided By Operating Activities	563,387	331,678	273,136
Proceeds from sales, maturities, calls and prepayments of fixed maturity securities	14,459	72,834	13,047
Cost of fixed maturity securities purchased	(6,516)	(48,501)	0
Proceeds from sales of equity securities	3,662	24,237	65,379
Cost of equity securities purchased	(310)	(7,731)	(16,660)
Net change in short-term investments	(315,622)	451,846	58,970
Decrease (increase) in notes receivable due from subsidiaries	0	0	75,645
Capital contributions to subsidiaries	(174,002)	(55,575)	(94,585)
Proceeds from sale of subsidiary	0	16,090	165,615
Cost of equity method investments	0	(5,000)	0
Other	2,694	(12,691)	4,779
Net Cash Used By Investing Activities	(475,635)	435,509	272,190
Repayment and retirement of senior long-term debt	0	(250,000)	(350,000)
Additions to senior long-term debt	592,596	0	0
Decrease in notes payable to subsidiaries	0	0	(32,753)
Repurchases of common stock	(572,728)	(445,479)	(290,796)
Dividends paid on preferred stock	(36,000)	(36,000)	(36,000)
Other	(1,273)	0	0
Net Cash Used By Financing Activities	(17,405)	(731,479)	(709,549)
Increase (decrease) in cash, cash equivalents, restricted cash and restricted cash equivalents	70,347	35,708	(164,223)
Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of year	650,955	615,247	779,470
CASH, CASH EQUIVALENTS, RESTRICTED CASH AND RESTRICTED CASH EQUIVALENTS AT END OF YEAR	721,302	650,955	615,247
Cash dividends received from subsidiaries, Parent Company	575,000	310,000	245,102
Noncash Capital Distribution to Subsidiaries, Parent Company	$ 0	$ 43,111	$ 923,980

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 07, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Subsequent Event [Line Items]
Net losses and loss adjustment expenses		$ 5,508,059	$ 5,360,559	$ 4,613,035
Minimum [Member] | Subsequent Event | California Wildfires (2025)
Subsequent Event [Line Items]
Net losses and loss adjustment expenses	$ 90,000
Maximum [Member] | Subsequent Event | California Wildfires (2025)
Subsequent Event [Line Items]
Net losses and loss adjustment expenses	$ 130,000