Markel (MKL) 10-Q 30 Oct 19 2019 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 22, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-15811
Entity Registrant Name	MARKEL CORPORATION
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	54-1959284
Entity Address, Address Line One	4521 Highwoods Parkway
Entity Address, City or Town	Glen Allen
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	23060-6148
City Area Code	804
Local Phone Number	747-0136
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	MKL
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		13,812,499
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001096343
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets [Abstract]
Fixed maturities, available-for-sale (amortized cost of $9,601,898 in 2019 and $9,950,773 in 2018)	$ 10,204,025	$ 10,043,188
Equity securities (cost of $3,204,316 in 2019 and $2,971,856 in 2018)	6,978,874	5,720,945
Short-term investments, available-for-sale (estimated fair value approximates cost	1,545,393	1,077,696
Total Investments	18,728,292	16,841,829
Cash and cash equivalents	2,715,455	2,014,168
Restricted cash and cash equivalents	484,314	382,264
Receivables	1,930,394	1,692,526
Reinsurance recoverables	5,372,156	5,221,947
Deferred policy acquisition costs	570,323	474,513
Prepaid reinsurance premiums	1,508,853	1,331,022
Goodwill	2,187,585	2,237,975
Intangible assets	1,659,129	1,726,196
Other assets	1,879,695	1,383,823
Total Assets	37,036,196	33,306,263
Liabilities and Equity [Abstract]
Unpaid losses and loss adjustment expenses	14,437,816	14,276,479
Life and annuity benefits	1,021,185	1,001,453
Unearned premiums	4,224,074	3,611,028
Payables to insurance and reinsurance companies	408,508	337,326
Senior long-term debt and other debt (estimated fair value of $4,257,000 in 2019 and $3,030,000 in 2018)	3,896,962	3,009,577
Other liabilities	2,247,179	1,796,036
Total Liabilities	26,235,724	24,031,899
Redeemable noncontrolling interests	165,602	174,062
Commitments and contingencies
Shareholders' equity:
Common stock	3,402,934	3,392,993
Retained earnings	6,988,888	5,782,310
Accumulated other comprehensive income (loss)	231,632	(94,650)
Total Shareholders' Equity	10,623,454	9,080,653
Noncontrolling interests	11,416	19,649
Total Equity	10,634,870	9,100,302
Total Liabilities and Equity	$ 37,036,196	$ 33,306,263

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fixed maturities, available-for-sale amortized cost	$ 9,601,898	$ 9,950,773
Equity securities, cost	3,204,316	2,971,856
Senior long-term debt and other debt (estimated fair value)	$ 4,257,000	$ 3,030,000

Consolidated Statements Of Inco

Consolidated Statements Of Income And Comprehensive Income - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019		Sep. 30, 2018
OPERATING REVENUES
Earned premiums	$ 1,300,032		$ 1,185,323		$ 3,703,470		$ 3,484,528
Net investment income	113,382		106,307		339,395		319,710
Net realized investment gains (losses)	150		(496)		764		(9,084)
Change in fair value of equity securities	31,994		426,571		1,069,224		417,410
Net investment gains	32,144		426,075		1,069,988		408,326
Products revenues	386,708		362,577		1,237,178		1,129,036
Services and other revenues	200,792		155,667		594,631		456,833
Total Operating Revenues	2,033,058		2,235,949		6,944,662		5,798,433
OPERATING EXPENSES
Losses and loss adjustment expenses	752,134		736,846		2,118,000		1,951,142
Underwriting, acquisition and insurance expenses	475,219		441,961		1,392,747		1,317,921
Products expenses	354,404		341,718		1,098,968		1,062,000
Services and other expenses	153,358		132,024		498,760		394,311
Amortization of intangible assets	35,695	[1]	27,795	[2]	112,663	[3]	86,259	[4]
Impairment of goodwill and intangible assets	0		0		0		14,904
Total Operating Expenses	1,770,810		1,680,344		5,221,138		4,826,537
Operating Income	262,248		555,605		1,723,524		971,896
Interest expense	47,465		37,961		129,022		114,722
Net foreign exchange gains	(53,850)		(1,383)		(57,001)		(65,427)
Loss on early extinguishment of debt	6,705		0		6,705		0
Income Before Income Taxes	261,928		519,027		1,644,798		922,601
Income tax expense	57,975		109,999		356,849		299,580
Net Income	203,953		409,028		1,287,949		623,021
Net income (loss) attributable to noncontrolling interests	(1,684)		(410)		8,587		(342)
Net Income to Shareholders	205,637		409,438		1,279,362		623,363
OTHER COMPREHENSIVE INCOME
Net holding gains (losses) arising during the period	48,315		(91,002)		329,113		(306,069)
Reclassification adjustments for net losses included in net income	203		10,573		760		5,496
Change in net unrealized gains (losses) on available-for-sale investments, net of taxes	48,518		(80,429)		329,873		(300,573)
Change in foreign currency translation adjustments, net of taxes	(4,606)		(14,471)		(5,978)		(19,968)
Change in net actuarial pension loss, net of taxes	462		509		2,338		1,741
Total Other Comprehensive Income (Loss)	44,374		(94,391)		326,233		(318,800)
Comprehensive Income (Loss)	248,327		314,637		1,614,182		304,221
Comprehensive income (loss) attributable to noncontrolling interests	(1,742)		(469)		8,538		(382)
Comprehensive Income to Shareholders	$ 250,069		$ 315,106		$ 1,605,644		$ 304,603
NET INCOME PER SHARE
Basic (in dollars per share)	$ 13.97		$ 28.56		$ 92.92		$ 44.29
Diluted (in dollars per share)	$ 13.95		$ 28.50		$ 92.84		$ 44.21
[1]	Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments.
[2]	Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments.
[3]	Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments.
[4]	Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments.

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Equity - USD ($) $ in Thousands	Total	Total Equity [Member]	Total Shareholders' Equity [Member]	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]	Redeemable Noncontrolling Interests [Member]	Nephila Holdings Limited [Member]Total Equity [Member]	Nephila Holdings Limited [Member]Noncontrolling Interests [Member]	Nephila Holdings Limited [Member]Redeemable Noncontrolling Interests [Member]
Balance at Dec. 31, 2017		$ 9,501,581	$ 9,504,148	$ 3,381,834	$ 3,776,743	$ 2,345,571	$ (2,567)
Balance, shares at Dec. 31, 2017				13,904,000
Balance, redeemable noncontrolling interests at Dec. 31, 2017								$ 166,269
Net income (loss)	$ 623,021	622,094	623,363		623,363	0	(1,269)	927
Total other comprehensive income (loss)	(318,800)	(318,760)	(318,760)		0	(318,760)	0	(40)
Comprehensive Income (Loss)	304,221	303,334	304,603				(1,269)	887
Issuance of common stock		2	2	$ 2	0	0	0	0
Issuance of common stock, shares				8,000
Repurchase of common stock		(30,829)	(30,829)	$ 0	(30,829)	0	0	0
Repurchase of common stock, shares				(28,000)
Restricted stock units expensed		15,521	15,521	$ 15,521	0	0	0	0
Restricted stock units expensed, shares				0
Adjustment of redeemable noncontrolling interests		(6,621)	(6,621)	$ 0	(6,621)	0	0	6,621
Adjustment of redeemable noncontrolling interests, shares				0
Purchase of noncontrolling interest		(4,986)	(4,986)	$ (4,986)	0	0	0	(7,104)
Purchase of noncontrolling interest, shares				0
Other		1,827	1,829	$ (49)	1,878	0	(2)	(7,934)
Other, shares				0
Balance at Sep. 30, 2018		9,780,154	9,783,992	$ 3,392,322	6,576,562	(184,892)	(3,838)
Balance, shares at Sep. 30, 2018				13,884,000
Balance, redeemable noncontrolling interests at Sep. 30, 2018								158,739
Balance at Jun. 30, 2018		9,477,414	9,480,860	$ 3,387,121	6,184,299	(90,560)	(3,446)
Balance, shares at Jun. 30, 2018				13,886,000
Balance, redeemable noncontrolling interests at Jun. 30, 2018								155,998
Net income (loss)	409,028	409,079	409,438		409,438	0	(359)	(51)
Total other comprehensive income (loss)	(94,391)	(94,332)	(94,332)		0	(94,332)	0	(59)
Comprehensive Income (Loss)	314,637	314,747	315,106				(359)	(110)
Issuance of common stock		0	0	$ 0	0	0	0	0
Issuance of common stock, shares				4,000
Repurchase of common stock		(6,572)	(6,572)	$ 0	(6,572)	0	0	0
Repurchase of common stock, shares				(6,000)
Restricted stock units expensed		3,292	3,292	$ 3,292	0	0	0	0
Restricted stock units expensed, shares				0
Adjustment of redeemable noncontrolling interests		(12,035)	(12,035)	$ 0	(12,035)	0	0	12,035
Adjustment of redeemable noncontrolling interests, shares				0
Purchase of noncontrolling interest		600	600	$ 600	0	0	0	(7,065)
Purchase of noncontrolling interest, shares				0
Other		2,708	2,741	$ 1,309	1,432	0	(33)	(2,119)
Other, shares				0
Balance at Sep. 30, 2018		9,780,154	9,783,992	$ 3,392,322	6,576,562	(184,892)	(3,838)
Balance, shares at Sep. 30, 2018				13,884,000
Balance, redeemable noncontrolling interests at Sep. 30, 2018								158,739
Balance at Dec. 31, 2018	9,100,302	9,100,302	9,080,653	$ 3,392,993	5,782,310	(94,650)	19,649
Balance, shares at Dec. 31, 2018				13,888,000
Balance, redeemable noncontrolling interests at Dec. 31, 2018	174,062							174,062
Net income (loss)	1,287,949	1,275,177	1,279,362		1,279,362	0	(4,185)	12,772
Total other comprehensive income (loss)	326,233	326,282	326,282		0	326,282	0	(49)
Comprehensive Income (Loss)	1,614,182	1,601,459	1,605,644				(4,185)	12,723
Issuance of common stock		43	43	$ 43	0	0	0	0
Issuance of common stock, shares				7,000
Repurchase of common stock	$ (81,100)	(81,998)	(81,998)	$ 0	(81,998)	0	0	0
Repurchase of common stock, shares	(77,991)			(80,000)
Restricted stock units expensed		14,282	14,282	$ 14,282	0	0	0	0
Restricted stock units expensed, shares				0
Adjustment to Nephila purchase price allocation			0	$ 0	0	0			$ (8,250)	$ (8,250)	$ 51
Adjustment to Nephila purchase price allocation, shares				0
Adjustment of redeemable noncontrolling interests		9,464	9,464	$ 0	9,464	0	0	(9,464)
Adjustment of redeemable noncontrolling interests, shares				0
Purchase of noncontrolling interest		(4,219)	(4,219)	$ (4,219)	0	0	0	(4,542)
Purchase of noncontrolling interest, shares				0
Other		3,787	(415)	$ (165)	(250)	0	4,202	(7,228)
Other, shares				0
Balance at Sep. 30, 2019	$ 10,634,870	10,634,870	10,623,454	$ 3,402,934	6,988,888	231,632	11,416
Balance, shares at Sep. 30, 2019				13,815,000
Balance, redeemable noncontrolling interests at Sep. 30, 2019	165,602							165,602
Balance at Jun. 30, 2019		10,413,081	10,396,365	$ 3,400,964	6,808,201	187,200	16,716
Balance, shares at Jun. 30, 2019				13,826,000
Balance, redeemable noncontrolling interests at Jun. 30, 2019								151,297
Net income (loss)	203,953	200,047	205,637		205,637	0	(5,590)	3,906
Total other comprehensive income (loss)	44,374	44,432	44,432		0	44,432	0	(58)
Comprehensive Income (Loss)	248,327	244,479	250,069				(5,590)	3,848
Issuance of common stock		43	43	$ 43	0	0	0	0
Issuance of common stock, shares				1,000
Repurchase of common stock		(12,732)	(12,732)	$ 0	(12,732)	0	0	0
Repurchase of common stock, shares				(12,000)
Restricted stock units expensed		2,410	2,410	$ 2,410	0	0	0	0
Restricted stock units expensed, shares				0
Adjustment of redeemable noncontrolling interests		(12,221)	(12,221)	$ 0	(12,221)	0	0	12,221
Adjustment of redeemable noncontrolling interests, shares				0
Purchase of noncontrolling interest		(483)	(483)	$ (483)	0	0	0	483
Purchase of noncontrolling interest, shares				0
Other		293	3	$ 0	3	0	290	(2,247)
Other, shares				0
Balance at Sep. 30, 2019	10,634,870	$ 10,634,870	$ 10,623,454	$ 3,402,934	$ 6,988,888	$ 231,632	$ 11,416
Balance, shares at Sep. 30, 2019				13,815,000
Balance, redeemable noncontrolling interests at Sep. 30, 2019	$ 165,602							$ 165,602

Condensed Consolidated Statemen

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
OPERATING ACTIVITIES
Net income	$ 1,287,949	$ 623,021
Adjustments to reconcile net income to net cash provided by operating activities	(575,991)	140,155
Net Cash Provided By Operating Activities	711,958	763,176
INVESTING ACTIVITIES
Proceeds from sales of fixed maturities and equity securities	326,304	361,768
Proceeds from maturities, calls and prepayments of fixed maturities	446,625	459,517
Cost of fixed maturities and equity securities purchased	(657,563)	(1,409,263)
Net change in short-term investments	(451,408)	257,288
Cost of equity method investments	(216,806)	(3,647)
Additions to property and equipment	(95,457)	(78,886)
Proceeds from disposals of fixed assets	15,949	1,528
Acquisitions, net of cash acquired	(25,627)	(11,314)
Other	825	(30,206)
Net Cash Used By Investing Activities	(657,158)	(453,215)
FINANCING ACTIVITIES
Additions to senior long-term debt and other debt	1,578,823	145,813
Repayment of senior long-term debt and other debt	(680,516)	(246,049)
Premiums and fees related to early extinguishment of debt	(10,086)	0
Repurchases of common stock	(81,998)	(30,829)
Payment of contingent consideration	(14,113)	(15,914)
Purchase of noncontrolling interests	(9,754)	(13,523)
Distributions to noncontrolling interests	(7,147)	(7,964)
Other	(4,565)	(3,303)
Net Cash Provided (Used) By Financing Activities	770,644	(171,769)
Effect of foreign currency rate changes on cash, cash equivalents, restricted cash and restricted cash equivalents	(22,107)	(12,096)
Increase in cash, cash equivalents, restricted cash and restricted cash equivalents	803,337	126,096
Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of period	2,396,432	2,500,846
CASH, CASH EQUIVALENTS, RESTRICTED CASH AND RESTRICTED CASH EQUIVALENTS AT END OF PERIOD	$ 3,199,769	$ 2,626,942

Summary Of Significant Accounti

Summary Of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Summary Of Significant Accounting Policies	Summary of Significant Accounting Policies Markel Corporation is a diverse financial holding company serving a variety of niche markets. Markel Corporation's principal business markets and underwrites specialty insurance products. Through its wholly owned subsidiary, Markel Ventures, Inc. (Markel Ventures), Markel Corporation also owns interests in various businesses that operate outside of the specialty insurance marketplace. a) Basis of Presentation. The consolidated balance sheet as of September 30, 2019 and the related consolidated statements of income and comprehensive income and changes in equity for the quarters and nine months ended September 30, 2019 and 2018 , and the consolidated statements of cash flows for the nine months ended September 30, 2019 and 2018 are unaudited. In the opinion of management, all adjustments necessary for fair presentation of such consolidated financial statements have been included. Such adjustments consist only of normal, recurring items. Interim results are not necessarily indicative of results of operations for the entire year. The consolidated balance sheet as of December 31, 2018 was derived from Markel Corporation's audited annual consolidated financial statements. The accompanying consolidated financial statements have been prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) and include the accounts of Markel Corporation 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 year amounts have been reclassified to conform to the current presentation. The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results may differ materially from the estimates and assumptions used in preparing the consolidated financial statements. The consolidated financial statements and notes are presented as permitted by Form 10-Q and do not contain certain information included in the Company's annual consolidated financial statements and notes. Readers are urged to review the Company's 2018 Annual Report on Form 10-K for a more complete description of the Company's business and accounting policies. b) Leases. Following the adoption of Financial Accounting Standards Board (FASB) Accounting Standards Update (ASU) No. 2016-02, Leases (Topic 842), effective January 1, 2019, the present value of future lease payments for the Company’s leases with terms greater than 12 months are included on the consolidated balance sheet as lease liabilities and right-of-use lease assets. The Company’s lease portfolio primarily consists of operating leases for real estate. 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 has elected the practical expedient to account for lease components and any associated non-lease components 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 obligation to make lease payments arising from the lease, 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 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. Lease liabilities and lease assets are included in other liabilities and other assets, respectively, on the consolidated balance sheet.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Effective January 1, 2019, the Company adopted FASB ASU No. 2016-02, Leases (Topic 842) and several other ASUs that were issued as amendments to ASU No. 2016-02, which require lessees to record most leases in their balance sheets as a lease liability with a corresponding right-of-use asset, but continue to recognize the related rent expense within net income. The Company elected to apply the optional transition method, under which an entity initially applies the new lease standard to existing leases at the beginning of the period of adoption. The Company continues to apply the previous guidance to 2018 and prior periods. The Company also elected the package of practical expedients permitted under the transition guidance within the new standard, which, among other things, allowed companies to carry forward their historical lease classification. As a result of adopting ASU No. 2016-02, the Company recorded a right-of-use lease asset and a lease liability of $243.7 million and $264.6 million , respectively as of January 1, 2019. ASU No. 2016-02 also requires expanded lease disclosures, which are included in note 12 . Adoption of this standard did not have a material impact on the Company’s results of operations or cash flows. The following ASU issued by the FASB is relevant to the Company's operations and was adopted effective January 1, 2019. This ASU did not have a material impact on the Company's financial position, results of operations or cash flows: • ASU No. 2017-08, Receivables—Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The FASB subsequently issued several ASUs as amendments to ASU No. 2016-13. The standard replaces the current incurred loss model used to measure impairment losses with a current expected credit loss (CECL) model for financial instruments measured at amortized cost, including reinsurance recoverables and trade receivables. For available-for-sale fixed maturities, which are measured at fair value, the ASU requires entities to record impairments as an allowance, rather than a reduction of the amortized cost, as is currently required under the other-than-temporary impairment model. ASU No. 2016-13 becomes effective for the Company during the first quarter of 2020 and will be applied using a modified retrospective approach through a cumulative-effect adjustment to retained earnings as of January 1, 2020. The Company is currently evaluating ASU No. 2016-13 to determine the potential impact that adopting this standard will have on its consolidated financial statements. Application of the CECL model will not impact the Company's investment portfolio, none of which is measured at amortized cost, but will impact certain of the Company's other financial assets, including its reinsurance recoverables and receivables. Upon adoption of this ASU, any impairment losses on the Company's available-for-sale fixed maturities will be recorded as an allowance, subject to reversal, rather than as a reduction in amortized cost. In August 2018, the FASB issued ASU No. 2018-12, Financial Services—Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts. The ASU requires insurance entities with long duration contracts to: (1) review and, if there is a change, update the assumptions used to measure cash flows at least annually, as well as update the discount rate assumption at each reporting date; (2) measure all market risk benefits associated with deposit (or account balance) contracts at fair value; and (3) disclose liability rollforwards and information about significant inputs, judgments, assumptions and methods used in measurement, including changes thereto and the effect of those changes on measurement. In August 2019, the FASB proposed an update to ASU No. 2018-12 to defer its effective date. The proposed update would make the ASU effective for the Company during the first quarter of 2022. ASU No. 2018-12 will, among other things, impact the discount rate used in estimating reserves for the Company’s life and annuity reinsurance portfolio, which is in runoff. Currently, the discount rate assumption is locked-in for the life of the contracts, unless there is a loss recognition event. The Company is currently evaluating ASU No. 2018-12 to determine the impact that adopting this standard will have on its consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The ASU aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software and hosting arrangements that include an internal-use software license. The ASU requires an entity to expense the implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement. Currently, such costs are generally expensed as incurred. ASU No. 2018-15 becomes effective for the Company during the first quarter of 2020 and may be applied on a prospective or retrospective basis. Early adoption is permitted. The Company is currently evaluating its information technology projects to determine the impact that adopting ASU No. 2018-15 will have on its consolidated financial statements. The following ASUs issued by the FASB are relevant to the Company's operations and are not yet effective. These ASUs are not expected to have a material impact on the Company's financial position, results of operations or cash flows: • ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement • ASU No. 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans • ASU No. 2018-17, Consolidation (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Acquisitions	Acquisitions The Hagerty Group, LLC In June 2019, the Company acquired a minority ownership interest in The Hagerty Group, LLC (Hagerty Group), a company that primarily operates as a managing general agent under the names Hagerty Insurance Agency and Hagerty Classic Marine Insurance Agency (collectively, Hagerty). Hagerty Group also includes Hagerty Re, a Bermuda Class 3 reinsurance company. Hagerty Group is a leading automotive lifestyle brand and provider of specialty insurance to automobile enthusiasts. Total consideration for the Company’s investment was $212.5 million . The Company's investment in Hagerty Group is accounted for under the equity method and is included in other assets on the Company’s consolidated balance sheet. Essentia Insurance Company, one of the Company’s insurance subsidiaries, is the exclusive insurance underwriter for Hagerty in the U.S., and a portion of this insurance is ceded to Hagerty Re. Gross written premiums attributable to Hagerty for the quarter and nine months ended September 30, 2019 were $120.8 million and $333.7 million , respectively, of which $57.7 million and $159.8 million were ceded to Hagerty Re. Brahmin Leather Works, LLC In October 2018, the Company acquired 90% of Brahmin Leather Works, LLC (Brahmin), a Massachusetts-based privately held creator of fashion leather handbags. Total consideration for the acquisition was $192.9 million , which included cash consideration of $172.3 million . Total consideration also includes the estimated fair value of contingent consideration the Company expects to pay based on Brahmin’s earnings as defined in the purchase agreement, for the period of 2019 through 2021. As of December 31, 2018, the purchase price was preliminarily allocated to the acquired assets and liabilities of Brahmin based on estimated fair value at the acquisition date. During the second quarter of 2019, the Company completed the process of determining the fair value of the assets and liabilities acquired with Brahmin. The Company recognized goodwill of $63.8 million , which is primarily attributable to expected future earnings and cash flow potential of Brahmin. The majority of the goodwill recognized is deductible for income tax purposes. The Company also recognized other intangible assets of $93.3 million , which includes $57.0 million of customer relationships, $35.0 million of trade names and $1.3 million of other intangible assets, which are being amortized over a weighted average period of 16 years , 16 years and 8 years , respectively. The Company also recognized redeemable noncontrolling interests of $19.6 million . Results attributable to Brahmin are included in the Company’s Markel Ventures segment. Nephila Holdings Ltd. In November 2018, the Company acquired all of the outstanding shares of Nephila Holdings Ltd. (Nephila), a Bermuda-based investment fund manager offering a broad range of investment products, including insurance-linked securities, catastrophe bonds, insurance swaps and weather derivatives. Nephila generates revenue primarily through management and incentive fees. Total consideration for the acquisition was $974.4 million , all of which was cash consideration. As of December 31, 2018, the purchase price was preliminarily allocated to the acquired assets and liabilities of Nephila based on estimated fair values at the acquisition date. During the third quarter of 2019, the Company completed the process of determining the fair value of the assets and liabilities acquired with Nephila. The Company recognized goodwill of $434.2 million , which is primarily attributable to expected future earnings and cash flow potential of Nephila. None of the goodwill recognized is deductible for income tax purposes. The Company also recognized other intangible assets of $551.0 million , which includes $468.0 million of investment management agreements, $32.0 million of broker relationships, $27.0 million of technology and $24.0 million of trade names, which are being amortized over a weighted average period of 17 years , 12 years , 6 years and 14 years , respectively. The Company also recognized noncontrolling interests of $15.1 million attributable to certain consolidated subsidiaries of Nephila that are not wholly-owned. Nephila operates as a separate business unit and its operating results are not included in a reportable segment.

Investments

Investments	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Investments	Investments a) The following tables summarize the Company's available-for-sale investments. Commercial and residential mortgage-backed securities include securities issued by U.S. government-sponsored enterprises and U.S. government agencies. September 30, 2019 (dollars in thousands) Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Estimated Fair Value Fixed maturities: U.S. Treasury securities $ 293,954 $ 3,201 $ (199 ) $ 296,956 U.S. government-sponsored enterprises 331,356 28,628 (11 ) 359,973 Obligations of states, municipalities and political subdivisions 4,047,517 272,703 (112 ) 4,320,108 Foreign governments 1,471,214 158,652 (14,252 ) 1,615,614 Commercial mortgage-backed securities 1,708,617 81,696 (230 ) 1,790,083 Residential mortgage-backed securities 868,317 42,015 (663 ) 909,669 Asset-backed securities 9,881 46 (3 ) 9,924 Corporate bonds 871,042 37,905 (7,249 ) 901,698 Total fixed maturities 9,601,898 624,846 (22,719 ) 10,204,025 Short-term investments 1,546,129 364 (1,100 ) 1,545,393 Investments, available-for-sale $ 11,148,027 $ 625,210 $ (23,819 ) $ 11,749,418 December 31, 2018 (dollars in thousands) Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Estimated Fair Value Fixed maturities: U.S. Treasury securities $ 248,286 $ 308 $ (1,952 ) $ 246,642 U.S. government-sponsored enterprises 357,765 5,671 (4,114 ) 359,322 Obligations of states, municipalities and political subdivisions 4,285,068 96,730 (28,868 ) 4,352,930 Foreign governments 1,482,826 98,356 (21,578 ) 1,559,604 Commercial mortgage-backed securities 1,691,572 3,154 (44,527 ) 1,650,199 Residential mortgage-backed securities 886,501 6,170 (12,499 ) 880,172 Asset-backed securities 19,614 7 (213 ) 19,408 Corporate bonds 979,141 13,234 (17,464 ) 974,911 Total fixed maturities 9,950,773 223,630 (131,215 ) 10,043,188 Short-term investments 1,080,027 443 (2,774 ) 1,077,696 Investments, available-for-sale $ 11,030,800 $ 224,073 $ (133,989 ) $ 11,120,884 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. September 30, 2019 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Fair Value Gross Unrealized Holding Losses Estimated Fair Value Gross Unrealized Holding Losses Estimated Fair Value Gross Unrealized Holding Losses Fixed maturities: U.S. Treasury securities $ 7,481 $ (6 ) $ 81,674 $ (193 ) $ 89,155 $ (199 ) U.S. government-sponsored enterprises — — 35,386 (11 ) 35,386 (11 ) Obligations of states, municipalities and political subdivisions 1,053 (13 ) 25,289 (99 ) 26,342 (112 ) Foreign governments 157,525 (5,764 ) 166,998 (8,488 ) 324,523 (14,252 ) Commercial mortgage-backed securities — — 34,144 (230 ) 34,144 (230 ) Residential mortgage-backed securities 2,105 (9 ) 71,317 (654 ) 73,422 (663 ) Asset-backed securities — — 2,242 (3 ) 2,242 (3 ) Corporate bonds 168,843 (5,862 ) 78,519 (1,387 ) 247,362 (7,249 ) Total fixed maturities 337,007 (11,654 ) 495,569 (11,065 ) 832,576 (22,719 ) Short-term investments 115,139 (1,100 ) — — 115,139 (1,100 ) Total $ 452,146 $ (12,754 ) $ 495,569 $ (11,065 ) $ 947,715 $ (23,819 ) At September 30, 2019 , the Company held 220 available-for-sale securities with a total estimated fair value of $947.7 million and gross unrealized losses of $23.8 million . Of these 220 securities, 162 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $495.6 million and gross unrealized losses of $11.1 million . The Company does not intend to sell or believe it will be required to sell these available-for-sale securities before recovery of their amortized cost. December 31, 2018 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Fair Value Gross Unrealized Holding Losses Estimated Fair Value Gross Unrealized Holding Losses Estimated Fair Value Gross Unrealized Holding Losses Fixed maturities: U.S. Treasury securities $ 2,922 $ (83 ) $ 156,352 $ (1,869 ) $ 159,274 $ (1,952 ) U.S. government-sponsored enterprises 88,854 (1,923 ) 96,337 (2,191 ) 185,191 (4,114 ) Obligations of states, municipalities and political subdivisions 656,573 (12,455 ) 453,736 (16,413 ) 1,110,309 (28,868 ) Foreign governments 419,764 (14,461 ) 84,776 (7,117 ) 504,540 (21,578 ) Commercial mortgage-backed securities 653,410 (10,128 ) 709,971 (34,399 ) 1,363,381 (44,527 ) Residential mortgage-backed securities 276,777 (3,685 ) 242,949 (8,814 ) 519,726 (12,499 ) Asset-backed securities 1,645 (11 ) 17,030 (202 ) 18,675 (213 ) Corporate bonds 313,164 (10,965 ) 222,761 (6,499 ) 535,925 (17,464 ) Total fixed maturities 2,413,109 (53,711 ) 1,983,912 (77,504 ) 4,397,021 (131,215 ) Short-term investments 197,643 (2,774 ) — — 197,643 (2,774 ) Total $ 2,610,752 $ (56,485 ) $ 1,983,912 $ (77,504 ) $ 4,594,664 $ (133,989 ) At December 31, 2018 , the Company held 1,005 securities with a total estimated fair value of $4.6 billion and gross unrealized losses of $134.0 million . Of these 1,005 securities, 541 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $2.0 billion and gross unrealized losses of $77.5 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 deemed other-than-temporary. 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 other-than-temporary impairment, including the length of time and the extent to which fair value has been below cost and the financial condition and near-term prospects of the issuer. For fixed maturities, the Company considers whether it intends to sell the security or if it is more likely than not that it will be required to sell the security before recovery, the implied yield-to-maturity, the credit quality of the issuer and the ability to recover all amounts outstanding when contractually due. For fixed maturities where the Company intends to sell the security or it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost, a decline in fair value is considered to be other-than-temporary and 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. If the decline in fair value of a fixed maturity below its amortized cost is considered to be other-than-temporary based upon other considerations, 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-related portion of the other-than-temporary impairment, which is recognized in net income, resulting in a new cost basis for the security. Any remaining decline in fair value represents the non-credit portion of the other-than-temporary impairment, which is recognized in other comprehensive income. c) The amortized cost and estimated fair value of fixed maturities at September 30, 2019 are shown below by contractual maturity. (dollars in thousands) Amortized Cost Estimated Fair Value Due in one year or less $ 491,999 $ 485,791 Due after one year through five years 1,285,281 1,310,381 Due after five years through ten years 2,081,192 2,197,791 Due after ten years 3,156,611 3,500,386 7,015,083 7,494,349 Commercial mortgage-backed securities 1,708,617 1,790,083 Residential mortgage-backed securities 868,317 909,669 Asset-backed securities 9,881 9,924 Total fixed maturities $ 9,601,898 $ 10,204,025 d) The following table presents the components of net investment income . Quarter Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2019 2018 2019 2018 Interest: Municipal bonds (tax-exempt) $ 17,456 $ 19,588 $ 54,167 $ 60,810 Municipal bonds (taxable) 18,442 18,634 55,634 54,487 Other taxable bonds 40,560 40,932 122,583 117,949 Short-term investments, including overnight deposits 14,294 13,719 38,259 36,224 Dividends on equity securities 25,493 21,721 73,486 66,202 Income (loss) from equity method investments 366 (3,556 ) 3,436 (3,268 ) Other 797 255 3,971 242 117,408 111,293 351,536 332,646 Investment expenses (4,026 ) (4,986 ) (12,141 ) (12,936 ) Net investment income $ 113,382 $ 106,307 $ 339,395 $ 319,710 e) The following table presents net investment gains and the change in net unrealized gains (losses) on available-for-sale investments. Quarter Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2019 2018 2019 2018 Realized gains: Sales and maturities of fixed maturities $ 856 $ 2,916 $ 2,660 $ 3,748 Sales and maturities of short-term investments 1,540 1,447 1,288 1,624 Other 124 171 584 1,008 Total realized gains 2,520 4,534 4,532 6,380 Realized losses: Sales and maturities of fixed maturities (198 ) (1,003 ) (1,109 ) (2,652 ) Sales and maturities of short-term investments (2,172 ) (3,997 ) (2,659 ) (10,044 ) Other — (30 ) — (2,768 ) Total realized losses (2,370 ) (5,030 ) (3,768 ) (15,464 ) Net realized investment gains (losses) 150 (496 ) 764 (9,084 ) Change in fair value of equity securities: Change in fair value of equity securities sold during the period (345 ) 151 35,786 10,230 Change in fair value of equity securities held at the end of the period 32,339 426,420 1,033,438 407,180 Change in fair value of equity securities 31,994 426,571 1,069,224 417,410 Net investment gains $ 32,144 $ 426,075 $ 1,069,988 $ 408,326 Change in net unrealized gains (losses) on available-for-sale investments included in other comprehensive income (loss): Fixed maturities $ 95,170 $ (103,083 ) $ 509,712 $ (384,176 ) Short-term investments (2,266 ) 1,417 1,595 239 Net increase (decrease) $ 92,904 $ (101,666 ) $ 511,307 $ (383,937 )

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Accounting Standards Codification (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 maturities and short-term investments. Short-term investments include certificates of deposit, commercial paper, discount notes and treasury bills with original maturities of one year or less. Fair value for available-for-sale investments and equity securities are 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 maturities and equity securities. In determining fair value, the Company generally does not adjust the prices obtained from the pricing service. The Company obtains an understanding of the pricing service's valuation methodologies and related inputs, which include, but are not limited to, reported trades, benchmark yields, issuer spreads, bids, offers, duration, credit ratings, estimated cash flows and prepayment speeds. The Company validates prices provided by the pricing service by reviewing prices from other pricing sources and analyzing pricing data in certain instances. The Company has evaluated the various types of securities in its investment portfolio to determine an appropriate fair value hierarchy level based upon trading activity and the observability of market inputs. Level 1 investments include those traded on an active exchange, such as the New York Stock Exchange. Level 2 investments include U.S. Treasury securities, U.S. government-sponsored enterprises, municipal bonds, foreign government bonds, commercial mortgage-backed securities, residential mortgage-backed securities, asset-backed securities and corporate debt securities. Level 3 investments include the Company's investments in certain insurance-linked securities funds managed by Markel CATCo Investment Management Ltd. (MCIM), a consolidated subsidiary, that are not traded on an active exchange, as further described and defined in note 14 (the Markel CATCo Funds), 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 maturities are classified as Level 2 investments. The fair value of fixed maturities is normally derived through recent reported trades for identical or similar securities, making adjustments through the reporting date based upon available market observable data described above. If there are no recent reported trades, the fair value of fixed maturities may be derived through the use of matrix pricing or model processes, where future cash flow expectations are developed based upon collateral performance and discounted at an estimated market rate. Significant inputs used to determine the fair value of obligations of states, municipalities and political subdivisions, corporate bonds and obligations of foreign governments include reported trades, benchmark yields, issuer spreads, bids, offers, credit information and estimated cash flows. Significant inputs used to determine the fair value of commercial mortgage-backed securities, residential mortgage-backed securities and asset-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. Due to the significance of unobservable inputs required in measuring the fair value of the Company's investments in the Markel CATCo Funds, these investments are classified as Level 3 within the fair value hierarchy. The fair value of the securities are derived using their reported net asset value (NAV) as the primary input, as well as other observable and unobservable inputs as deemed necessary by management. Management has obtained an understanding of the inputs, assumptions, process, and controls used to determine NAV, which is calculated by an independent third party. Unobservable inputs to the NAV calculations include assumptions around premium earnings patterns and loss reserve estimates for the underlying securitized reinsurance contracts in which the Markel CATCo Funds invest. Significant unobservable inputs used in the valuation of these investments include an adjustment to include the fair value of the equity that was issued by one of the Markel CATCo Funds in exchange for notes receivable, rather than cash, which is excluded from NAV. The determination of fair value of the securities also considers external market data, including the trading price relative to its NAV of CATCo Reinsurance Opportunities Fund Ltd. (CROF), a comparable security traded on a market operated by the London Stock Exchange and on the Bermuda Stock Exchange further described in note 14 . Generally, the Company's investments in the Markel CATCo Funds are redeemable annually as of January 1 st of each calendar year. However, in years with significant loss events on the underlying securitized reinsurance contracts, as was the case in 2018 and 2017, payment for the redemption of certain investments may be restricted for up to three years. The Company's valuation policies and procedures for Level 3 investments are determined by management. Fair value measurements are analyzed quarterly to ensure the change in fair value from prior periods is reasonable relative to management's understanding of the underlying investments, recent market trends and external market data. 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 for senior long-term debt and other debt is generally derived through recent reported trades for identical securities, 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. September 30, 2019 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments: Fixed maturities, available-for-sale: U.S. Treasury securities $ — $ 296,956 $ — $ 296,956 U.S. government-sponsored enterprises — 359,973 — 359,973 Obligations of states, municipalities and political subdivisions — 4,320,108 — 4,320,108 Foreign governments — 1,615,614 — 1,615,614 Commercial mortgage-backed securities — 1,790,083 — 1,790,083 Residential mortgage-backed securities — 909,669 — 909,669 Asset-backed securities — 9,924 — 9,924 Corporate bonds — 901,698 — 901,698 Total fixed maturities, available-for-sale — 10,204,025 — 10,204,025 Equity securities: Insurance, banks and other financial institutions 2,247,952 — 44,489 2,292,441 Industrial, consumer and all other 4,686,433 — — 4,686,433 Total equity securities 6,934,385 — 44,489 6,978,874 Short-term investments, available-for-sale 1,444,357 101,036 — 1,545,393 Total investments $ 8,378,742 $ 10,305,061 $ 44,489 $ 18,728,292 December 31, 2018 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments: Fixed maturities, available-for-sale: U.S. Treasury securities $ — $ 246,642 $ — $ 246,642 U.S. government-sponsored enterprises — 359,322 — 359,322 Obligations of states, municipalities and political subdivisions — 4,352,930 — 4,352,930 Foreign governments — 1,559,604 — 1,559,604 Commercial mortgage-backed securities — 1,650,199 — 1,650,199 Residential mortgage-backed securities — 880,172 — 880,172 Asset-backed securities — 19,408 — 19,408 Corporate bonds — 974,911 — 974,911 Total fixed maturities, available-for-sale — 10,043,188 — 10,043,188 Equity securities: Insurance, banks and other financial institutions 1,876,811 — 53,728 1,930,539 Industrial, consumer and all other 3,790,406 — — 3,790,406 Total equity securities 5,667,217 — 53,728 5,720,945 Short-term investments, available-for-sale 981,616 96,080 — 1,077,696 Total investments $ 6,648,833 $ 10,139,268 $ 53,728 $ 16,841,829 The following table summarizes changes in Level 3 investments measured at fair value on a recurring basis. Quarter Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2019 2018 2019 2018 Equity securities, beginning of period $ 37,988 $ 119,675 $ 53,728 $ 168,809 Purchases — — 500 28,900 Sales (857 ) — (7,726 ) (34,653 ) Net investment gains (losses) on Level 3 investments 7,358 2,418 (2,013 ) (40,963 ) Transfers into Level 3 — — — — Transfers out of Level 3 — — — — Equity securities, end of period $ 44,489 $ 122,093 $ 44,489 $ 122,093 There were no transfers into or out of Level 1 and Level 2 during the quarter and nine months ended September 30, 2019 and 2018 . The Company did not have any assets or liabilities measured at fair value on a non-recurring basis during the nine months ended September 30, 2019 and 2018 .

Segment Reporting Disclosures

Segment Reporting Disclosures	9 Months Ended
	Sep. 30, 2019
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Segment Reporting Disclosures	Segment Reporting Disclosures The Company's 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 its underwriting results, management 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 and facultative placements written across the Company. The Reinsurance segment includes all treaty reinsurance written across the Company. All investing activities related to the Company's underwriting operations are included in the Investing segment. The Markel Ventures segment primarily consists of controlling interests in a diverse portfolio of businesses that operate in various industries. The chief operating decision maker reviews and assesses Markel Ventures’ performance in the aggregate, as a single operating segment. The Company's other operations include the results of the Company's program services business and the results of the Company's insurance-linked securities operations attributable to MCIM and, beginning November 2018, Nephila. The Company's other operations also include results for underwriting 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 the Company's other operations are considered to be reportable segments. Segment profit for the Company's underwriting segments is measured by underwriting profit. The property and casualty insurance industry commonly defines underwriting profit as earned premiums net of losses and loss adjustment expenses and underwriting, acquisition and insurance expenses. Underwriting profit does not replace operating income or net income computed in accordance with U.S. GAAP as a measure of profitability. Underwriting profit or loss provides a basis for management to evaluate the Company's underwriting performance. Segment profit for the Investing segment is measured by net investment income and net investment gains. Segment profit for the Markel Ventures segment is measured by operating income. For management reporting purposes, the Company allocates assets to its investing and Markel Ventures segments and certain of its other operations, including its program services and insurance-linked securities operations. 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 attributed to the Company's other operations. Underwriting and investing assets are not allocated to the Company's underwriting segments since the Company does not manage its assets by underwriting segment. The Company does not allocate capital expenditures for long-lived assets to either of its underwriting segments for management reporting purposes. The following tables summarize the Company's segment disclosures. Quarter Ended September 30, 2019 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures (1) Other (2) Consolidated Gross premium volume $ 1,418,363 $ 226,387 $ — $ — $ 619,742 $ 2,264,492 Net written premiums 1,181,919 187,180 — — 1,285 1,370,384 Earned premiums 1,058,869 240,144 — — 1,019 1,300,032 Losses and loss adjustment expenses: Current accident year (722,172 ) (178,058 ) — — — (900,230 ) Prior accident years 135,029 13,800 — — (733 ) 148,096 Amortization of policy acquisition costs (218,710 ) (61,925 ) — — — (280,635 ) Other operating expenses (171,731 ) (20,436 ) — — (2,417 ) (194,584 ) Underwriting profit (loss) 81,285 (6,475 ) — — (2,131 ) 72,679 Net investment income — — 113,220 162 — 113,382 Net investment gains — — 32,144 — — 32,144 Products revenues — — — 386,708 — 386,708 Services and other revenues — — — 109,373 91,419 200,792 Products expenses — — — (354,404 ) — (354,404 ) Services and other expenses — — — (96,015 ) (57,343 ) (153,358 ) Amortization of intangible assets (3) — — — (10,357 ) (25,338 ) (35,695 ) Segment profit (loss) $ 81,285 $ (6,475 ) $ 145,364 $ 35,467 $ 6,607 $ 262,248 Interest expense (47,465 ) Net foreign exchange gains 53,850 Loss on early extinguishment of debt (6,705 ) Income before income taxes $ 261,928 U.S. GAAP combined ratio (4) 92 % 103 % NM (5) 94 % (1) Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $12.9 million for the quarter ended September 30, 2019 . (2) Other represents the total profit (loss) attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment. (3) Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments. (4) The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums. (5) NM - Ratio is not meaningful Quarter Ended September 30, 2018 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures (1) Other (2) Consolidated Gross premium volume $ 1,248,150 $ 234,360 $ — $ — $ 561,261 $ 2,043,771 Net written premiums 1,021,684 195,349 — — (762 ) 1,216,271 Earned premiums 961,062 225,277 — — (1,016 ) 1,185,323 Losses and loss adjustment expenses: Current accident year (674,529 ) (186,505 ) — — 48 (860,986 ) Prior accident years 111,117 12,681 — — 342 124,140 Amortization of policy acquisition costs (182,857 ) (58,991 ) — — — (241,848 ) Other operating expenses (172,340 ) (26,125 ) — — (1,648 ) (200,113 ) Underwriting profit (loss) 42,453 (33,663 ) — — (2,274 ) 6,516 Net investment income — — 106,164 143 — 106,307 Net investment gains — — 426,075 — — 426,075 Products revenues — — — 362,577 — 362,577 Services and other revenues — — — 106,694 48,973 155,667 Products expenses — — — (341,718 ) — (341,718 ) Services and other expenses — — — (94,924 ) (37,100 ) (132,024 ) Amortization of intangible assets (3) — — — (9,139 ) (18,656 ) (27,795 ) Segment profit (loss) $ 42,453 $ (33,663 ) $ 532,239 $ 23,633 $ (9,057 ) $ 555,605 Interest expense (37,961 ) Net foreign exchange gains 1,383 Income before income taxes $ 519,027 U.S. GAAP combined ratio (4) 96 % 115 % NM (5) 99 % (1) Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $13.0 million for the quarter ended September 30, 2018 . (2) Other represents the total loss attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment. (3) Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments. (4) The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums. (5) NM - Ratio is not meaningful Nine Months Ended September 30, 2019 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures (1) Other (2) Consolidated Gross premium volume $ 3,979,559 $ 963,145 $ — $ — $ 1,823,977 $ 6,766,681 Net written premiums 3,306,447 844,949 — — 1,719 4,153,115 Earned premiums 3,023,865 678,382 — — 1,223 3,703,470 Losses and loss adjustment expenses: Current accident year (1,998,042 ) (456,870 ) — — — (2,454,912 ) Prior accident years 309,324 20,695 — — 6,893 336,912 Amortization of policy acquisition costs (627,318 ) (178,209 ) — — — (805,527 ) Other operating expenses (526,884 ) (58,301 ) — — (2,035 ) (587,220 ) Underwriting profit 180,945 5,697 — — 6,081 192,723 Net investment income — — 338,783 612 — 339,395 Net investment gains — — 1,069,988 — — 1,069,988 Products revenues — — — 1,237,178 — 1,237,178 Services and other revenues — — — 330,653 263,978 594,631 Products expenses — — — (1,098,968 ) — (1,098,968 ) Services and other expenses — — — (290,745 ) (208,015 ) (498,760 ) Amortization of intangible assets (3) — — — (31,674 ) (80,989 ) (112,663 ) Segment profit (loss) $ 180,945 $ 5,697 $ 1,408,771 $ 147,056 $ (18,945 ) $ 1,723,524 Interest expense (129,022 ) Net foreign exchange gains 57,001 Loss on early extinguishment of debt (6,705 ) Income before income taxes $ 1,644,798 U.S. GAAP combined ratio (4) 94 % 99 % NM (5) 95 % (1) Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $40.4 million for the nine months ended September 30, 2019 . (2) Other represents the total profit (loss) attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment. (3) Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments. (4) The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums. (5) NM - Ratio is not meaningful Nine Months Ended September 30, 2018 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures (1) Other (2) Consolidated Gross premium volume $ 3,575,340 $ 935,498 $ — $ — $ 1,577,250 $ 6,088,088 Net written premiums 2,935,789 795,136 — — 754 3,731,679 Earned premiums 2,782,107 702,854 — — (433 ) 3,484,528 Losses and loss adjustment expenses: Current accident year (1,855,190 ) (485,678 ) — — — (2,340,868 ) Prior accident years 369,775 18,135 — — 1,816 389,726 Amortization of policy acquisition costs (554,185 ) (178,818 ) — — — (733,003 ) Other operating expenses (523,239 ) (59,433 ) — — (2,246 ) (584,918 ) Underwriting profit (loss) 219,268 (2,940 ) — — (863 ) 215,465 Net investment income — — 319,253 457 — 319,710 Net investment gains — — 408,326 — — 408,326 Products revenues — — — 1,129,036 — 1,129,036 Services and other revenues — — — 311,048 145,785 456,833 Products expenses — — — (1,062,000 ) — (1,062,000 ) Services and other expenses — — — (273,876 ) (120,435 ) (394,311 ) Amortization of intangible assets (3) — — — (29,332 ) (56,927 ) (86,259 ) Impairment of goodwill and intangible assets — — — (14,904 ) — (14,904 ) Segment profit (loss) $ 219,268 $ (2,940 ) $ 727,579 $ 60,429 $ (32,440 ) $ 971,896 Interest expense (114,722 ) Net foreign exchange gains 65,427 Income before income taxes $ 922,601 U.S. GAAP combined ratio (4) 92 % 100 % NM (5) 94 % (1) Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $38.5 million for the nine months ended September 30, 2018 . (2) Other represents the total loss attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment. (3) Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments. (4) The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums. (5) NM - Ratio is not meaningful b) The following table reconciles segment assets to the Company's consolidated balance sheets. (dollars in thousands) September 30, 2019 December 31, 2018 Segment assets: Investing $ 21,893,706 $ 19,100,790 Underwriting 6,896,240 6,451,984 Markel Ventures 2,257,878 2,124,506 Total segment assets 31,047,824 27,677,280 Other operations 5,988,372 5,628,983 Total assets $ 37,036,196 $ 33,306,263

Products, Services and Other Re

Products, Services and Other Revenues	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Products, Services and Other Revenues	Products, Services and Other Revenues The amount of revenues from contracts with customers was $535.7 million and $472.2 million for the quarters ended September 30, 2019 and 2018 , respectively, and $1.7 billion and $1.5 billion for the nine months ended September 30, 2019 and 2018 , respectively. The following table disaggregates 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 and comprehensive income . Quarter Ended September 30, 2019 2018 (dollars in thousands) Markel Ventures Other Total Markel Ventures Other Total Products $ 378,421 $ — $ 378,421 $ 350,981 $ — $ 350,981 Services 97,062 17,516 114,578 95,071 7,841 102,912 Investment management — 42,750 42,750 — 18,258 18,258 Total revenues from contracts with customers 475,483 60,266 535,749 446,052 26,099 472,151 Program services and other fronting arrangements — 30,775 30,775 — 22,478 22,478 Other 20,598 378 20,976 23,219 396 23,615 Total $ 496,081 $ 91,419 $ 587,500 $ 469,271 $ 48,973 $ 518,244 Nine Months Ended September 30, 2019 2018 (dollars in thousands) Markel Ventures Other Total Markel Ventures Other Total Products $ 1,198,124 $ — $ 1,198,124 $ 1,095,461 $ — $ 1,095,461 Services 291,617 64,142 355,759 276,548 25,737 302,285 Investment management — 113,738 113,738 — 52,965 52,965 Total revenues from contracts with customers 1,489,741 177,880 1,667,621 1,372,009 78,702 1,450,711 Program services and other fronting arrangements — 84,953 84,953 — 65,810 65,810 Other 78,090 1,145 79,235 68,075 1,273 69,348 Total $ 1,567,831 $ 263,978 $ 1,831,809 $ 1,440,084 $ 145,785 $ 1,585,869 The following table presents receivables and customer deposits related to contracts with customers. (dollars in thousands) September 30, 2019 December 31, 2018 Receivables $ 267,638 $ 247,532 Customer deposits $ 70,984 $ 48,238

Unpaid Losses And Loss Adjustme

Unpaid Losses And Loss Adjustment Expenses	9 Months Ended
	Sep. 30, 2019
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Unpaid Losses And Loss Adjustment Expenses	Unpaid Losses and Loss Adjustment Expenses The following table presents a reconciliation of consolidated beginning and ending reserves for losses and loss adjustment expenses. Nine Months Ended September 30, (dollars in thousands) 2019 2018 Net reserves for losses and loss adjustment expenses, beginning of year $ 9,214,443 $ 8,964,945 Foreign currency movements (51,544 ) (35,754 ) Adjusted net reserves for losses and loss adjustment expenses, beginning of year 9,162,899 8,929,191 Incurred losses and loss adjustment expenses: Current accident year 2,454,912 2,340,868 Prior accident years (336,942 ) (389,740 ) Total incurred losses and loss adjustment expenses 2,117,970 1,951,128 Payments: Current accident year 410,493 390,245 Prior accident years 1,597,117 1,438,224 Total payments 2,007,610 1,828,469 Effect of foreign currency rate changes (669 ) 368 Net reserves for losses and loss adjustment expenses, end of period 9,272,590 9,052,218 Reinsurance recoverables on unpaid losses 5,165,226 4,836,271 Gross reserves for losses and loss adjustment expenses, end of period $ 14,437,816 $ 13,888,489 For the nine months ended September 30, 2019 , incurred losses and loss adjustment expenses included $336.9 million of favorable development on prior years' loss reserves, which included $257.7 million of favorable development on the Company's general liability, workers' compensation and professional liability product lines within the Insurance segment, and aviation, auto and whole account product lines within the Reinsurance segment. In 2019 , underwriting results included $42.6 million of underwriting loss from Hurricane Dorian and Typhoon Faxai (2019 Catastrophes). The underwriting loss on the 2019 Catastrophes was comprised of $45.1 million of estimated losses and loss adjustment expenses partially offset by $2.5 million of net assumed reinstatement premiums. The estimated losses and loss adjustment expenses on the 2019 Catastrophes for the nine months ended September 30, 2019 were net of estimated ceded losses of $4.8 million . Both the gross and net loss estimates on the 2019 Catastrophes represent the Company's best estimate of losses based upon information currently available. The Company's estimate for these losses is based on preliminary industry loss estimates, output from both industry and proprietary models as well as a review of in-force contracts, and for Hurricane Dorian, claims received to date and detailed policy level reviews. Early industry loss estimates for Typhoon Faxai have a wide range of variability. While the Company believes its reserves for the 2019 Catastrophes as of September 30, 2019 are adequate, the Company continues to closely monitor industry loss estimates and reported claims and will adjust its estimates of gross and net losses as new information becomes available. For the nine months ended September 30, 2018 , incurred losses and loss adjustment expenses included $389.7 million of favorable development on prior years' loss reserves, which included $312.2 million of favorable development on the Company's general liability, workers' compensation, marine and energy and professional liability product lines within the Insurance segment and credit and surety and marine and energy product lines within the Reinsurance segment. In 2018 , underwriting results included $75.7 million of underwriting loss from Hurricane Florence and Typhoon Jebi (2018 Catastrophes). The underwriting loss on the 2018 Catastrophes was comprised of $77.8 million of estimated losses and loss adjustment expenses partially offset by $2.1 million of net assumed reinstatement premiums. The estimated losses and loss adjustment expenses on the 2018 Catastrophes for the nine months ended September 30, 2018 were net of estimated ceded losses of $28.6 million .

Reinsurance

Reinsurance	9 Months Ended
	Sep. 30, 2019
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance The following tables summarize the effect of reinsurance and retrocessional reinsurance on premiums written and earned. Quarter Ended September 30, 2019 2018 (dollars in thousands) Direct Assumed Ceded Net Premiums Direct Assumed Ceded Net Premiums Underwriting: Written $ 1,358,243 $ 282,506 $ (271,094 ) $ 1,369,655 $ 1,207,605 $ 274,898 $ (266,788 ) $ 1,215,715 Earned 1,219,103 327,431 (246,965 ) 1,299,569 1,113,763 313,378 (242,120 ) 1,185,021 Program services and other: Written 584,196 39,547 (623,014 ) 729 529,958 31,310 (560,712 ) 556 Earned 576,576 20,399 (596,512 ) 463 480,694 13,046 (493,438 ) 302 Consolidated: Written 1,942,439 322,053 (894,108 ) 1,370,384 1,737,563 306,208 (827,500 ) 1,216,271 Earned $ 1,795,679 $ 347,830 $ (843,477 ) $ 1,300,032 $ 1,594,457 $ 326,424 $ (735,558 ) $ 1,185,323 Nine Months Ended September 30, 2019 2018 (dollars in thousands) Direct Assumed Ceded Net Premiums Direct Assumed Ceded Net Premiums Underwriting: Written $ 3,808,759 $ 1,129,440 $ (786,704 ) $ 4,151,495 $ 3,429,666 $ 1,081,171 $ (781,126 ) $ 3,729,711 Earned 3,510,203 946,648 (754,505 ) 3,702,346 3,221,946 965,586 (703,785 ) 3,483,747 Program services and other: Written 1,754,613 73,869 (1,826,862 ) 1,620 1,537,412 39,839 (1,575,283 ) 1,968 Earned 1,629,659 49,672 (1,678,207 ) 1,124 1,374,443 16,784 (1,390,446 ) 781 Consolidated: Written 5,563,372 1,203,309 (2,613,566 ) 4,153,115 4,967,078 1,121,010 (2,356,409 ) 3,731,679 Earned $ 5,139,862 $ 996,320 $ (2,432,712 ) $ 3,703,470 $ 4,596,389 $ 982,370 $ (2,094,231 ) $ 3,484,528 Substantially all of the premiums written and earned in the Company's program services business for the quarter and nine months ended September 30, 2019 and 2018 was ceded. The percentage of consolidated ceded earned premiums to gross earned premiums was 39% and 40% for the quarter and nine months ended September 30, 2019 , respectively, and 38% for both the quarter and nine months ended September 30, 2018 . The percentage of consolidated assumed earned premiums to net earned premiums was 27% for both the quarter and nine months ended September 30, 2019 , and 28% for both the quarter and nine months ended September 30, 2018 . Substantially all of the incurred losses and loss adjustment expenses in the Company's program services business, which totaled $412.7 million and $1.1 billion for the quarter and nine months ended September 30, 2019 , respectively, and $329.9 million and $959.5 million for the quarter and nine months ended September 30, 2018 , respectively, were ceded. Incurred losses and loss adjustment expenses for the Company's underwriting operations were net of ceded incurred losses and loss adjustment expenses of $94.4 million and $443.8 million for the quarter and nine months ended September 30, 2019 , respectively, and $171.1 million and $394.9 million for the quarter and nine months ended September 30, 2018 , respectively.

Life and Annuity Benefits Life

Life and Annuity Benefits Life and Annuity Benefits	9 Months Ended
	Sep. 30, 2019
Liability for Future Policy Benefit, before Reinsurance [Abstract]
Liability for Future Policy Benefits and Unpaid Claims Disclosure [Text Block]	Life and Annuity Benefits Life and annuity benefits are compiled on a reinsurance contract-by-contract basis 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 must make estimates and assumptions based on cedent experience, industry mortality tables, and expense and investment experience, including a provision for adverse deviation. The assumptions used to determine policy benefit reserves are generally locked-in for the life of the contract unless an unlocking event occurs. Loss recognition testing is performed to determine if existing policy benefit reserves, together with the present value of future gross premiums and expected investment income earned thereon, are adequate to cover the present value of future benefits, settlement and maintenance costs. If the existing policy benefit reserves are not sufficient, the locked-in assumptions are revised to current best estimate assumptions and a charge to earnings for life and annuity benefits is recognized at that time. Life and annuity benefits are also adjusted to the extent unrealized gains on the investments supporting the policy benefit reserves would result in a reserve deficiency if those gains were realized. During the quarter and nine months ended September 30, 2019 , the Company recognized a reserve deficiency resulting from a decrease in the market yield on the investment portfolio supporting the policy benefit reserves by increasing life and annuity benefits by $31.3 million and $93.1 million , respectively, and decreasing the change in net unrealized holding gains included in other comprehensive income by a corresponding amount. As of September 30, 2019 , the cumulative adjustment to life and annuity benefits attributable to unrealized gains on the underlying investment portfolio totaled $93.1 million . No adjustment was required for the quarter or nine months ended September 30, 2018 .

Senior Long-Term Debt and Other

Senior Long-Term Debt and Other Debt Senior Long-Term Debt and Other Debt	9 Months Ended
	Sep. 30, 2019
Senior Long-Term Debt and Other Debt [Abstract]
Senior Long-Term Debt and Other Debt [Text Block]	Senior Long-Term Debt and Other Debt In April 2019 , the Company entered into a credit agreement for a new 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 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 leverage ratio and maintain a minimum amount of consolidated net worth, as well as other customary covenants and events of default. Markel Corporation, along with Alterra Finance LLC, guaranteed the obligations under the facility. This facility replaced the Company's previous $300 million revolving credit facility and is scheduled to expire in April 2024 . There were no borrowings outstanding on either credit facility as of September 30, 2019 or December 31, 2018 . In May 2019 , the Company issued $600 million of 5.0% unsecured senior notes due May 20, 2049 . Net proceeds to the Company were $592.2 million , before expenses. In September 2019, the Company used a portion of these proceeds to retire its 7.125% unsecured senior notes due September 30, 2019 ( $234.8 million aggregate principal outstanding at December 31, 2018). The Company expects to use the remainder of the proceeds for general corporate purposes. In September 2019 , the Company issued $300 million of 3.35% unsecured senior notes due September 17, 2029 and $500 million of 4.15% unsecured senior notes due September 17, 2050 . Net proceeds to the Company were $297.5 million and $494.5 million , respectively, before expenses. The Company used a portion of these proceeds to purchase $125.2 million of principal on its 6.25% unsecured senior notes due September 30, 2020 and $97.8 million of principal on its 5.35% unsecured senior notes due June 1, 2021 through a tender offer at a total purchase price of $130.1 million and $103.0 million , respectively. In connection with the tender offer and purchase, the Company recognized a loss on early extinguishment of debt of $6.7 million during the quarter and nine months ended September 30, 2019 . The Company used a portion of the remaining proceeds to redeem the remaining outstanding balance on its 6.25% and 5.35% unsecured senior notes, as described below, and expects to use the remainder for general corporate purposes. In October 2019 , the Company redeemed the remaining outstanding balance on its 6.25% unsecured senior notes due September 30, 2020 ( $224.8 million aggregate principal outstanding at September 30, 2019) and 5.35% unsecured senior notes due June 1, 2021 ( $152.2 million aggregate principal outstanding at September 30, 2019) for a total purchase price of $233.4 million and $160.2 million , respectively.

Leases Leases

Leases Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases of Lessee Disclosure [Text Block]	Leases The Company's leases primarily consist of operating leases for real estate and have remaining terms of up to 15 years . Total lease costs for operating leases were $14.0 million and $47.2 million for the quarter and nine months ended September 30, 2019, respectively. The following table summarizes details for the Company's operating leases recorded on the consolidated balance sheet as of September 30, 2019 . (dollars in thousands) Right-of-use lease assets $ 230,474 Lease liabilities $ 254,119 Weighted average remaining lease term 8.6 years Weighted average discount rate 3.4 % The table below summarizes maturities of the Company’s operating lease liabilities as of September 30, 2019 , which reconciles to total lease liabilities included in other liabilities in the Company’s consolidated balance sheet. Years Ending December 31, (dollars in thousands) 2019 $ 14,250 2020 45,536 2021 42,202 2022 36,483 2023 30,903 2024 and thereafter 124,176 Total lease payments 293,550 Less imputed interest (39,431 ) Total operating lease liabilities $ 254,119

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate was 22% and 32% for the nine months ended September 30, 2019 and 2018 , respectively. In 2018, the Company decided to elect to treat its two most significant United Kingdom subsidiaries as domestic corporations for U.S. tax purposes. As a result, the earnings and profits of those subsidiaries are no longer considered to be indefinitely reinvested, and during the nine months ended September 30, 2018 , the Company recorded a one-time deferred tax charge of $102.0 million related to the book and tax basis differences attributable to those subsidiaries. This tax charge represented 11% of the 2018 effective tax rate. The Company uses the estimated annual effective tax rate method for calculating its tax provision in interim periods. This method applies the Company's best estimate of the effective tax rate expected for the full year to year-to-date earnings before income taxes. Certain items, including those deemed to be unusual, infrequent or that cannot be reliably estimated (discrete items), such as the deferred tax charge described above, are excluded from the estimated annual effective tax rate and the related tax expense or benefit is reported in the same period as the related item. The Company's estimated annual effective tax rate was 21% and 20% for the nine months ended September 30, 2019 and 2018 , respectively. The Internal Revenue Service is currently examining the Company’s 2017 federal income tax return. The Company believes its income tax liabilities were adequate as of September 30, 2019 , however, these liabilities could be adjusted as a result of this examination.

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	Variable Interest Entities MCIM, a wholly-owned consolidated subsidiary of the Company, is an insurance-linked securities investment fund manager and reinsurance manager headquartered in Bermuda. Results attributable to MCIM are not included in a reportable segment. MCIM serves as the insurance manager for Markel CATCo Re Ltd. (Markel CATCo Re), a Bermuda Class 3 reinsurance company, and as the investment manager for Markel CATCo Reinsurance Fund Ltd., a Bermuda exempted mutual fund company comprised of multiple segregated accounts (Markel CATCo Funds). MCIM also serves as the investment manager to CATCo Reinsurance Opportunities Fund Ltd. (CROF), a limited liability closed-end Bermuda exempted mutual fund company which invests substantially all of its assets in Markel CATCo Reinsurance Fund Ltd. The Markel CATCo Funds issue multiple classes of nonvoting, redeemable preference shares to investors through its funds and the Markel CATCo Funds are primarily invested in nonvoting preference shares of Markel CATCo Re. The underwriting results of Markel CATCo Re are attributed to the Markel CATCo Funds through those nonvoting preference shares. Voting shares in Markel CATCo Reinsurance Fund Ltd. and Markel CATCo Re are held by MCIM. The Markel CATCo Funds and Markel CATCo Re are considered VIEs, as their preference shareholders have no voting rights. MCIM has the power to direct the activities that most significantly impact the economic performance of these entities, but does not have a variable interest in any of the entities. Except as described below, the Company is not the primary beneficiary of the Markel CATCo Funds or Markel CATCo Re, and therefore does not consolidate these entities, as the Company's involvement is generally limited to that of an investment or insurance manager, receiving fees that are at market and commensurate with the level of effort required. Investment management and incentive fees earned by the Company from unconsolidated Markel CATCo Funds were $10.0 million and $18.3 million for the quarters ended September 30, 2019 and 2018 , respectively, and $28.1 million and $53.0 million for the nine months ended September 30, 2019 and 2018 , respectively. The Company is the sole investor in one of the Markel CATCo Funds, the Markel Diversified Fund, and consolidates that fund as its primary beneficiary. The following table presents the balance sheets of the Markel Diversified Fund, which are included on the Company's consolidated balance sheets. (dollars in thousands) September 30, 2019 December 31, 2018 Assets Equity securities: Investment in unconsolidated Markel CATCo Fund $ 16,866 $ 27,547 Other 198 1,082 Total Assets $ 17,064 $ 28,629 Liabilities and Equity Note payable $ 24,875 $ 24,875 Other 65 200 Total Liabilities 24,940 25,075 Total Equity (7,876 ) 3,554 Total Liabilities and Equity $ 17,064 $ 28,629 The assets of th e Markel Diversified Fund are available for use only by the Markel Diversified Fund, and are not available for use by the Company. Equity securities for the Markel Diversified Fund represent an investment in one of the unconsolidated Markel CATCo Funds and represent 3% of the outstanding preference shares of that fund as of September 30, 2019 and 2% as of December 31, 2018 . The note payable was delivered as part of the consideration provided for the Markel Diversified Fund's investment in the unconsolidated Fund. This note payable is included in senior long-term debt and other debt on the Company's consolidated balance sheets. Negative equity as of September 30, 2019 reflects cumulative losses on the Company's investment in the unconsolidated Fund in excess of the portion that has been funded in cash. Other than the note payable, any liabilities held by the Markel Diversified Fund have no recourse to the Company's general credit. The Company also has an investment in another one of the Markel CATCo Funds ( $27.6 million and $26.2 million as of September 30, 2019 and December 31, 2018 , respectively) but does not have the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE, and therefore does not consolidate that fund. The Company's exposure to risk from the unconsolidated Markel CATCo Funds and Markel CATCo Re was historically limited to its investment and any earned but uncollected fees. Beginning in 2019, the Company also entered into various reinsurance contracts on behalf of Markel CATCo Re. See note 15 . The Company has not issued any investment performance guarantees to these VIEs or their investors. As of September 30, 2019 , net assets under management of MCIM for unconsolidated VIEs were $3.0 billion . See note 18 .

Related Party Transactions Rela

Related Party Transactions Related Party Transactions	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	Related Party Transactions The Company engages in certain related party transactions in the normal course of business at arm's length. Details of the Company's transactions with related parties in its insurance-linked securities operations are included below. Nephila In November 2018, the Company expanded its insurance-linked securities operations through the acquisition of Nephila, which serves as the investment manager to several Bermuda, Ireland and U.S. based private funds (the Nephila Funds). To provide access for the Nephila Funds to the insurance, reinsurance and weather markets, Nephila also provides managing general agent services and acts as an insurance manager to certain Bermuda Class 3 and 3A reinsurance companies and as both a service company coverholder and agent with binding authority for Lloyd’s Syndicate 2357 (Syndicate 2357) (collectively, the Nephila Reinsurers). Nephila receives management fees for its investment and insurance management services from the Nephila Funds based on the net asset value of the accounts managed, and, for certain funds, incentive fees based on the annual performance of the funds it manages. Nephila also receives commissions from the Nephila Reinsurers, which are based on the direct written premiums of the insurance contracts placed. Total revenues attributed to services provided to the Nephila Funds and the Nephila Reinsurers for the quarter and nine months ended September 30, 2019 were $42.7 million and $124.7 million , respectively. Within the Company’s program services business, the Company has a program with Nephila through which the Company writes insurance policies that are ceded to Syndicate 2357 and certain other Nephila Reinsurers. Through this arrangement, Nephila utilizes certain of the Company’s licensed insurance companies to write U.S. catastrophe exposed property risk that is then ceded to Nephila Reinsurers. For the quarter and nine months ended September 30, 2019 , gross premiums written through the Company’s program with Nephila were $126.4 million and $360.6 million , respectively, all of which were ceded to Nephila Reinsurers. As of September 30, 2019 and December 31, 2018 , reinsurance recoverables on the consolidated balance sheets included $229.8 million and $179.8 million , respectively, due from Nephila Reinsurers. Under this program, 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 this program exceed the prescribed limit, the Company is obligated to pay such losses to the cedents without recourse to the Nephila Reinsurers. While the Company believes losses under this program are unlikely, those losses, if incurred, could be material to the Company’s consolidated results of operations and financial condition. The Company has also entered into both 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. Markel CATCo During the first quarter of 2019, the Company entered into various reinsurance contracts with third parties on behalf of Markel CATCo Re, an unconsolidated subsidiary, in exchange for ceding fees. These reinsurance contracts primarily cover losses for events that may occur during 2019, however, in some instances, coverage is also provided for adverse development on 2018 and prior accident years’ loss events. Incurred losses on these contracts are fully ceded to Markel CATCo Re. The loss exposures on these contracts are fully collateralized by Markel CATCo Re up to an amount that the Company believes is unlikely to be exceeded. The Company has credit risk from Markel CATCo Re for any uncollateralized amounts. Markel CATCo Re's ability to pay losses in excess of the collateralized amounts depends on the availability of funds that are not otherwise needed to pay losses on other contracts. As of September 30, 2019 , the Company's maximum exposure to loss on these contracts, representing the net uncollateralized risks, was $191.6 million . Total ceding fees attributed to these contracts were $8.8 million , of which $2.2 million and $6.6 million was earned and included in services and other revenues in the Company's consolidated statements of income and other comprehensive income for the quarter and nine months ended September 30, 2019 , respectively. Results attributed to these contracts are not included in a reportable segment. Within the Company's reinsurance operations, the Company also enters into reinsurance contracts that are ceded to Markel CATCo Re. Under this program, the Company retains 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 this program exceed the prescribed limit, the Company is obligated to pay such losses to the cedents without recourse to Markel CATCo Re. Gross premiums written and ceded to Markel CATCo Re were $0.1 million and $5.5 million for the quarter and nine months ended September 30, 2019 , respectively, and $1.0 million and $10.6 million for the quarter and nine months ended September 30, 2018 , respectively. See note 14

Shareholders' Equity

Shareholders' Equity	9 Months Ended
	Sep. 30, 2019
Net Income (Loss) per Share [Abstract]
Earnings Per Share [Text Block]	Shareholders' Equity a) In August 2019, the Board of Directors approved a new share repurchase program (the 2019 Program) to replace the previous share repurchase program that was approved by the Board of Directors in May 2018 (the 2018 Program). Consistent with the 2018 Program, the 2019 Program provides for the repurchase of up to $300 million of common stock and has no expiration date but may be terminated by the Board of Directors at any time. During the nine months ended September 30, 2019 , the Company repurchased an aggregate of 77,991 shares of common stock at a cost of $81.1 million , including 73,371 shares repurchased under the 2018 Program at a cost of $75.8 million , and 4,620 shares repurchased under the 2019 program at a cost of $5.4 million . In total, the Company repurchased 93,036 shares of common stock under the 2018 Program at a cost of $97.2 million . b) Net income per share was determined by dividing adjusted net income to shareholders by the applicable weighted average shares outstanding. Diluted net income per share is computed by dividing adjusted net income to shareholders by the weighted average number of common shares and dilutive potential common shares outstanding during the period. Quarter Ended September 30, Nine Months Ended September 30, (in thousands, except per share amounts) 2019 2018 2019 2018 Net income to shareholders $ 205,637 $ 409,438 $ 1,279,362 $ 623,363 Adjustment of redeemable noncontrolling interests (12,221 ) (12,035 ) 9,464 (6,621 ) Adjusted net income to shareholders $ 193,416 $ 397,403 $ 1,288,826 $ 616,742 Basic common shares outstanding 13,849 13,917 13,870 13,925 Dilutive potential common shares from restricted stock units and restricted stock 15 26 12 24 Diluted shares outstanding 13,864 13,943 13,882 13,949 Basic net income per share $ 13.97 $ 28.56 $ 92.92 $ 44.29 Diluted net income per share $ 13.95 $ 28.50 $ 92.84 $ 44.21

Other Comprehensive Income

Other Comprehensive Income	9 Months Ended
	Sep. 30, 2019
Other Comprehensive Income (Loss), Tax [Abstract]
Other Comprehensive Income	Other Comprehensive Income Other comprehensive income includes net holding gains on available-for-sale investments arising during the period, changes in unrealized other-than-temporary impairment losses on fixed maturities arising during the period and reclassification adjustments for net gains included in net income. Other comprehensive income also includes 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 taxes and noncontrolling interests, for the nine months ended September 30, 2019 and 2018 . (dollars in thousands) Unrealized Holding Gains (Losses) on Available-for-Sale Securities Foreign Currency Net Actuarial Pension Loss Total December 31, 2017 $ 2,477,973 $ (74,003 ) $ (58,399 ) $ 2,345,571 Cumulative effect of adoption of ASU No. 2016-01 (2,615,734 ) 2,492 — (2,613,242 ) Cumulative effect of adoption of ASU No. 2018-02 401,539 — — 401,539 January 1, 2018 263,778 (71,511 ) (58,399 ) 133,868 Other comprehensive income (loss) before reclassifications (306,069 ) (19,928 ) 1,741 (324,256 ) Amounts reclassified from accumulated other comprehensive income 5,496 — — 5,496 Total other comprehensive income (loss) (300,573 ) (19,928 ) 1,741 (318,760 ) September 30, 2018 $ (36,795 ) $ (91,439 ) $ (56,658 ) $ (184,892 ) December 31, 2018 $ 48,060 $ (86,652 ) $ (56,058 ) $ (94,650 ) Other comprehensive income (loss) before reclassifications 329,113 (5,929 ) 2,338 325,522 Amounts reclassified from accumulated other comprehensive loss 760 — — 760 Total other comprehensive income (loss) 329,873 (5,929 ) 2,338 326,282 September 30, 2019 $ 377,933 $ (92,581 ) $ (53,720 ) $ 231,632 Effective January 1, 2018, the Company adopted ASU No. 2016-01 and as a result, equity securities are no longer classified as available-for-sale with unrealized gains and losses recognized in other comprehensive income. Rather, changes in the fair value of equity securities are now recognized in net income. Upon adoption of this ASU, cumulative net unrealized gains on equity securities of $2.6 billion , net of deferred income taxes, were reclassified from accumulated other comprehensive income into retained earnings. Effective January 1, 2018, the Company adopted ASU No. 2018-02, which provided an option to reclassify tax effects remaining in accumulated other comprehensive income as a result of the Tax Cuts and Jobs Act to retained earnings. As a result of adopting the ASU, the Company reclassified $401.5 million of previously recognized deferred taxes from accumulated other comprehensive income into retained earnings as of January 1, 2018. The following table summarizes the tax expense (benefit) associated with each component of other comprehensive income (loss) . Quarter Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2019 2018 2019 2018 Change in net unrealized gains (losses) on available-for-sale investments: Net holding gains (losses) arising during the period $ 13,018 $ (24,047 ) $ 88,168 $ (84,825 ) Reclassification adjustments for net losses included in net income 54 2,810 202 1,461 Change in net unrealized gains (losses) on available-for-sale investments 13,072 (21,237 ) 88,370 (83,364 ) Change in foreign currency translation adjustments — 6,594 — 3,072 Change in net actuarial pension loss 123 135 622 463 Total $ 13,195 $ (14,508 ) $ 88,992 $ (79,829 ) The following table presents the details of amounts reclassified from accumulated other comprehensive income (loss) into income , by component. Quarter Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2019 2018 2019 2018 Unrealized holding gains (losses) on available-for-sale investments: Net realized investment losses, excluding other-than-temporary impairment losses (257 ) (13,383 ) (962 ) (6,957 ) Income taxes 54 2,810 202 1,461 Reclassification of unrealized holding losses, net of taxes $ (203 ) $ (10,573 ) $ (760 ) $ (5,496 ) Net actuarial pension loss: Underwriting, acquisition and insurance expenses $ (585 ) $ (644 ) $ (2,960 ) $ (2,204 ) Income taxes 123 135 622 463 Reclassification of net actuarial pension loss, net of taxes $ (462 ) $ (509 ) $ (2,338 ) $ (1,741 )

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Loss Contingency [Abstract]
Commitments and Contingencies	Commitments and Contingencies a) Late in the fourth quarter of 2018, the Company was contacted by and received inquiries from the U.S. Department of Justice, U.S. Securities and Exchange Commission and Bermuda Monetary Authority (collectively, Governmental Authorities) into loss reserves recorded in late 2017 and early 2018 at Markel CATCo Re (the Markel CATCo Inquiries), an unconsolidated subsidiary managed by MCIM. As a result, the Company engaged outside counsel to conduct an internal review. The internal review was completed in April 2019 and found no evidence that MCIM personnel acted in bad faith in exercising business judgment in the setting of reserves and making related disclosures during late 2017 and early 2018. The Company’s outside counsel has met with the Governmental Authorities and reported the findings from the internal review. The Markel CATCo Inquiries are ongoing. The Company cannot currently predict the duration, scope or result of the Markel CATCo Inquiries. During the internal review, the Company discovered violations of Markel policies by two senior executives of MCIM. As a result, these two executives are no longer with the Company (the MCIM Executive Departures). Between January 11, 2019 and March 7, 2019, several related putative class actions were filed in the U.S. District Court for the Southern District of New York against Markel Corporation and certain present or former officers and directors alleging violations of the federal securities laws relating to the matters that are the subject of the Markel CATCo Inquiries (the Markel Securities Litigation). The actions were consolidated. On August 6, 2019, the Markel Securities Litigation was voluntarily dismissed. On February 21, 2019, Anthony Belisle and Alissa Fredricks, two senior executives who are no longer with MCIM, each separately filed suit against MCIM and Markel Corporation, which suits were amended on March 29, 2019 and March 28, 2019, respectively (the MCIM Executive Suits). As amended, Mr. Belisle's complaint alleged claims for, among other things, breach of contract, defamation, invasion of privacy, indemnification, intentional interference with contractual relations and deceptive and unfair acts and sought relief of, among other things, $66.0 million in incentive compensation, enhanced compensatory damages, consequential damages, damages for emotional distress and injury to reputation, exemplary damages and attorneys' fees. In June 2019, MCIM, Markel Corporation, and Mr. Belisle agreed to commence binding arbitration to finally, fully and confidentially resolve the claims and counterclaims alleged in the action, and the Belisle suit was dismissed with prejudice in July 2019. The arbitrators have been selected and the arbitration proceeding has commenced. The Company believes that Mr. Belisle's claims are without merit and any material loss resulting from the Belisle binding arbitration to be remote. As amended, Ms. Fredricks' complaint alleged claims for, among other things, breach of contract, defamation, invasion of privacy, indemnification, intentional interference with contractual relations and deceptive and unfair acts and sought relief of, among other things, $7.5 million in incentive compensation, consequential damages, damages for emotional distress and injury to reputation, exemplary damages and attorneys' fees. In June 2019, the action filed by Ms. Fredricks was settled by mutual agreement to the satisfaction of all parties. The Markel CATCo Inquiries, Markel Securities Litigation, MCIM Executive Departures and MCIM Executive Suits, as well as other related matters of which the Company is currently unaware, could result in additional claims, litigation, investigations, enforcement actions or proceedings. For example, additional litigation may be filed by investors in the Markel CATCo Funds. The Company also could become subject to increased regulatory scrutiny, investigations or proceedings in any of the jurisdictions where it operates. If any regulatory authority takes action against the Company or the Company enters into an agreement to settle a matter, the Company may incur sanctions or be required to pay substantial fines or implement remedial measures that could prove costly or disruptive to its businesses and operations. Costs associated with the Company's internal review, including legal and investigation costs, as well as legal costs incurred in connection with any existing or future litigation, are being expensed as incurred. An unfavorable outcome in one or more of these matters, and others the Company cannot anticipate, could have a material adverse effect on the Company’s results of operations and financial condition. In addition, the Company may take further steps to mitigate potential risks or liabilities that may arise from the Markel CATCo Inquiries and related developments and some of those steps may have a material impact on the Company’s results of operations or financial condition. Even if an unfavorable outcome does not materialize, these matters, and actions the Company may take in response, could have an adverse impact on the Company’s reputation and result in substantial expense and disruption. In December 2018, investors in the Markel CATCo Funds were offered an additional redemption opportunity (the Special Redemption). Under the Special Redemption, investors in the Markel CATCo Funds were offered the option, through March 29, 2019, to redeem any or all shares held as of June 30, 2019. Through both the Special Redemption and the annual redemption for January 1, 2019, substantially all of the capital in the Markel CATCo Funds was tendered for redemption. In July 2019, MCIM announced it would cease accepting new investments in the Markel CATCo Funds and would not write any new business in Markel CATCo Re. Both the Markel CATCo Funds and Markel CATCo Re have been placed into run-off, returning capital to investors as it becomes available. The process is expected to take approximately three years. Payment for the redemptions of shares is an obligation of the Markel CATCo Funds, not Markel Corporation or its subsidiaries. b) The Company has reviewed events at one of its Markel Ventures products businesses. Since becoming aware of a matter late in the first quarter of 2018 related to the business's manufacture of products, the Company has conducted an investigation, reviewed the business's operations and developed remediation plans. Upon completion of its review during 2018, the Company accrued an expense of $33.5 million in its results of operations. This amount represented management’s best estimate of amounts considered probable including: remediation costs associated with the manufacture of products, costs associated with the investigation of this matter, a write down of inventory on hand and settlement costs related to pre-existing litigation. Final resolution of this matter could ultimately result in additional remediation and other costs, the amount of which cannot be estimated at this time, but which could have a material impact on the Company’s income before income taxes. However, management does not expect this matter ultimately will have a material adverse effect on the Company’s results of operations or financial condition. If a determination is made that additional costs associated with this matter are considered probable, these additional costs will be recognized as an expense in the Company's results of operations. As of September 30, 2019 , $21.4 million remained accrued for ongoing remediation efforts. In addition, 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. c) In September 2019, the Company announced the launch of Lodgepine Capital Management Limited (Lodgepine), its new retrocessional insurance-linked securities fund manager in Bermuda. Lodgepine's initial product offering will be Lodgepine Fund Limited, a property catastrophe retrocessional investment fund, which is expected to launch by January 1, 2020. The Company has committed to invest up to $100 million

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events In October 2019, Japan sustained losses from Typhoon Hagibis. Based on information currently available, the Company estimates its range of net incurred losses and loss adjustment expenses on this event is between $60 million and $120 million before income taxes. This estimated range of losses was derived based on preliminary industry loss estimates and reviews of in-force contracts. However, early industry loss estimates for Typhoon Hagibis have a wide range of variability. The Company will refine its estimate of losses, which will be recorded in the fourth quarter of 2019, as more details about the actual level of claims emerge.

Summary Of Significant Accoun_2

Summary Of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation. The consolidated balance sheet as of September 30, 2019 and the related consolidated statements of income and comprehensive income and changes in equity for the quarters and nine months ended September 30, 2019 and 2018 , and the consolidated statements of cash flows for the nine months ended September 30, 2019 and 2018 are unaudited. In the opinion of management, all adjustments necessary for fair presentation of such consolidated financial statements have been included. Such adjustments consist only of normal, recurring items. Interim results are not necessarily indicative of results of operations for the entire year. The consolidated balance sheet as of December 31, 2018 was derived from Markel Corporation's audited annual consolidated financial statements. The accompanying consolidated financial statements have been prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) and include the accounts of Markel Corporation 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 year amounts have been reclassified to conform to the current presentation. The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results may differ materially from the estimates and assumptions used in preparing the consolidated financial statements. The consolidated financial statements and notes are presented as permitted by Form 10-Q and do not contain certain information included in the Company's annual consolidated financial statements and notes. Readers are urged to review the Company's 2018 Annual Report on Form 10-K for a more complete description of the Company's business and accounting policies.
Leases	Leases. Following the adoption of Financial Accounting Standards Board (FASB) Accounting Standards Update (ASU) No. 2016-02, Leases (Topic 842), effective January 1, 2019, the present value of future lease payments for the Company’s leases with terms greater than 12 months are included on the consolidated balance sheet as lease liabilities and right-of-use lease assets. The Company’s lease portfolio primarily consists of operating leases for real estate. 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 has elected the practical expedient to account for lease components and any associated non-lease components 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 obligation to make lease payments arising from the lease, 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 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. Lease liabilities and lease assets are included in other liabilities and other assets, respectively, on the consolidated balance sheet.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Available-For-Sale Investments	The following tables summarize the Company's available-for-sale investments. Commercial and residential mortgage-backed securities include securities issued by U.S. government-sponsored enterprises and U.S. government agencies. September 30, 2019 (dollars in thousands) Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Estimated Fair Value Fixed maturities: U.S. Treasury securities $ 293,954 $ 3,201 $ (199 ) $ 296,956 U.S. government-sponsored enterprises 331,356 28,628 (11 ) 359,973 Obligations of states, municipalities and political subdivisions 4,047,517 272,703 (112 ) 4,320,108 Foreign governments 1,471,214 158,652 (14,252 ) 1,615,614 Commercial mortgage-backed securities 1,708,617 81,696 (230 ) 1,790,083 Residential mortgage-backed securities 868,317 42,015 (663 ) 909,669 Asset-backed securities 9,881 46 (3 ) 9,924 Corporate bonds 871,042 37,905 (7,249 ) 901,698 Total fixed maturities 9,601,898 624,846 (22,719 ) 10,204,025 Short-term investments 1,546,129 364 (1,100 ) 1,545,393 Investments, available-for-sale $ 11,148,027 $ 625,210 $ (23,819 ) $ 11,749,418 December 31, 2018 (dollars in thousands) Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Estimated Fair Value Fixed maturities: U.S. Treasury securities $ 248,286 $ 308 $ (1,952 ) $ 246,642 U.S. government-sponsored enterprises 357,765 5,671 (4,114 ) 359,322 Obligations of states, municipalities and political subdivisions 4,285,068 96,730 (28,868 ) 4,352,930 Foreign governments 1,482,826 98,356 (21,578 ) 1,559,604 Commercial mortgage-backed securities 1,691,572 3,154 (44,527 ) 1,650,199 Residential mortgage-backed securities 886,501 6,170 (12,499 ) 880,172 Asset-backed securities 19,614 7 (213 ) 19,408 Corporate bonds 979,141 13,234 (17,464 ) 974,911 Total fixed maturities 9,950,773 223,630 (131,215 ) 10,043,188 Short-term investments 1,080,027 443 (2,774 ) 1,077,696 Investments, available-for-sale $ 11,030,800 $ 224,073 $ (133,989 ) $ 11,120,884
Summary Of Gross Unrealized Investment Losses By Length Of Time That Securities Have Continuously Been In An Unrealized Loss Position	The following tables summarize gross unrealized investment losses on available-for-sale investments by the length of time that securities have continuously been in an unrealized loss position. September 30, 2019 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Fair Value Gross Unrealized Holding Losses Estimated Fair Value Gross Unrealized Holding Losses Estimated Fair Value Gross Unrealized Holding Losses Fixed maturities: U.S. Treasury securities $ 7,481 $ (6 ) $ 81,674 $ (193 ) $ 89,155 $ (199 ) U.S. government-sponsored enterprises — — 35,386 (11 ) 35,386 (11 ) Obligations of states, municipalities and political subdivisions 1,053 (13 ) 25,289 (99 ) 26,342 (112 ) Foreign governments 157,525 (5,764 ) 166,998 (8,488 ) 324,523 (14,252 ) Commercial mortgage-backed securities — — 34,144 (230 ) 34,144 (230 ) Residential mortgage-backed securities 2,105 (9 ) 71,317 (654 ) 73,422 (663 ) Asset-backed securities — — 2,242 (3 ) 2,242 (3 ) Corporate bonds 168,843 (5,862 ) 78,519 (1,387 ) 247,362 (7,249 ) Total fixed maturities 337,007 (11,654 ) 495,569 (11,065 ) 832,576 (22,719 ) Short-term investments 115,139 (1,100 ) — — 115,139 (1,100 ) Total $ 452,146 $ (12,754 ) $ 495,569 $ (11,065 ) $ 947,715 $ (23,819 ) December 31, 2018 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Fair Value Gross Unrealized Holding Losses Estimated Fair Value Gross Unrealized Holding Losses Estimated Fair Value Gross Unrealized Holding Losses Fixed maturities: U.S. Treasury securities $ 2,922 $ (83 ) $ 156,352 $ (1,869 ) $ 159,274 $ (1,952 ) U.S. government-sponsored enterprises 88,854 (1,923 ) 96,337 (2,191 ) 185,191 (4,114 ) Obligations of states, municipalities and political subdivisions 656,573 (12,455 ) 453,736 (16,413 ) 1,110,309 (28,868 ) Foreign governments 419,764 (14,461 ) 84,776 (7,117 ) 504,540 (21,578 ) Commercial mortgage-backed securities 653,410 (10,128 ) 709,971 (34,399 ) 1,363,381 (44,527 ) Residential mortgage-backed securities 276,777 (3,685 ) 242,949 (8,814 ) 519,726 (12,499 ) Asset-backed securities 1,645 (11 ) 17,030 (202 ) 18,675 (213 ) Corporate bonds 313,164 (10,965 ) 222,761 (6,499 ) 535,925 (17,464 ) Total fixed maturities 2,413,109 (53,711 ) 1,983,912 (77,504 ) 4,397,021 (131,215 ) Short-term investments 197,643 (2,774 ) — — 197,643 (2,774 ) Total $ 2,610,752 $ (56,485 ) $ 1,983,912 $ (77,504 ) $ 4,594,664 $ (133,989 )
Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturity Securities By Contractual Maturity Date	The amortized cost and estimated fair value of fixed maturities at September 30, 2019 are shown below by contractual maturity. (dollars in thousands) Amortized Cost Estimated Fair Value Due in one year or less $ 491,999 $ 485,791 Due after one year through five years 1,285,281 1,310,381 Due after five years through ten years 2,081,192 2,197,791 Due after ten years 3,156,611 3,500,386 7,015,083 7,494,349 Commercial mortgage-backed securities 1,708,617 1,790,083 Residential mortgage-backed securities 868,317 909,669 Asset-backed securities 9,881 9,924 Total fixed maturities $ 9,601,898 $ 10,204,025
Components Of Net Investment Income	The following table presents the components of net investment income . Quarter Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2019 2018 2019 2018 Interest: Municipal bonds (tax-exempt) $ 17,456 $ 19,588 $ 54,167 $ 60,810 Municipal bonds (taxable) 18,442 18,634 55,634 54,487 Other taxable bonds 40,560 40,932 122,583 117,949 Short-term investments, including overnight deposits 14,294 13,719 38,259 36,224 Dividends on equity securities 25,493 21,721 73,486 66,202 Income (loss) from equity method investments 366 (3,556 ) 3,436 (3,268 ) Other 797 255 3,971 242 117,408 111,293 351,536 332,646 Investment expenses (4,026 ) (4,986 ) (12,141 ) (12,936 ) Net investment income $ 113,382 $ 106,307 $ 339,395 $ 319,710
Summary Of Net Investment Gains And The Change In Net Unrealized Gains (Losses) On Available-For-Sale Investments	The following table presents net investment gains and the change in net unrealized gains (losses) on available-for-sale investments. Quarter Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2019 2018 2019 2018 Realized gains: Sales and maturities of fixed maturities $ 856 $ 2,916 $ 2,660 $ 3,748 Sales and maturities of short-term investments 1,540 1,447 1,288 1,624 Other 124 171 584 1,008 Total realized gains 2,520 4,534 4,532 6,380 Realized losses: Sales and maturities of fixed maturities (198 ) (1,003 ) (1,109 ) (2,652 ) Sales and maturities of short-term investments (2,172 ) (3,997 ) (2,659 ) (10,044 ) Other — (30 ) — (2,768 ) Total realized losses (2,370 ) (5,030 ) (3,768 ) (15,464 ) Net realized investment gains (losses) 150 (496 ) 764 (9,084 ) Change in fair value of equity securities: Change in fair value of equity securities sold during the period (345 ) 151 35,786 10,230 Change in fair value of equity securities held at the end of the period 32,339 426,420 1,033,438 407,180 Change in fair value of equity securities 31,994 426,571 1,069,224 417,410 Net investment gains $ 32,144 $ 426,075 $ 1,069,988 $ 408,326 Change in net unrealized gains (losses) on available-for-sale investments included in other comprehensive income (loss): Fixed maturities $ 95,170 $ (103,083 ) $ 509,712 $ (384,176 ) Short-term investments (2,266 ) 1,417 1,595 239 Net increase (decrease) $ 92,904 $ (101,666 ) $ 511,307 $ (383,937 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
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. September 30, 2019 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments: Fixed maturities, available-for-sale: U.S. Treasury securities $ — $ 296,956 $ — $ 296,956 U.S. government-sponsored enterprises — 359,973 — 359,973 Obligations of states, municipalities and political subdivisions — 4,320,108 — 4,320,108 Foreign governments — 1,615,614 — 1,615,614 Commercial mortgage-backed securities — 1,790,083 — 1,790,083 Residential mortgage-backed securities — 909,669 — 909,669 Asset-backed securities — 9,924 — 9,924 Corporate bonds — 901,698 — 901,698 Total fixed maturities, available-for-sale — 10,204,025 — 10,204,025 Equity securities: Insurance, banks and other financial institutions 2,247,952 — 44,489 2,292,441 Industrial, consumer and all other 4,686,433 — — 4,686,433 Total equity securities 6,934,385 — 44,489 6,978,874 Short-term investments, available-for-sale 1,444,357 101,036 — 1,545,393 Total investments $ 8,378,742 $ 10,305,061 $ 44,489 $ 18,728,292 December 31, 2018 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments: Fixed maturities, available-for-sale: U.S. Treasury securities $ — $ 246,642 $ — $ 246,642 U.S. government-sponsored enterprises — 359,322 — 359,322 Obligations of states, municipalities and political subdivisions — 4,352,930 — 4,352,930 Foreign governments — 1,559,604 — 1,559,604 Commercial mortgage-backed securities — 1,650,199 — 1,650,199 Residential mortgage-backed securities — 880,172 — 880,172 Asset-backed securities — 19,408 — 19,408 Corporate bonds — 974,911 — 974,911 Total fixed maturities, available-for-sale — 10,043,188 — 10,043,188 Equity securities: Insurance, banks and other financial institutions 1,876,811 — 53,728 1,930,539 Industrial, consumer and all other 3,790,406 — — 3,790,406 Total equity securities 5,667,217 — 53,728 5,720,945 Short-term investments, available-for-sale 981,616 96,080 — 1,077,696 Total investments $ 6,648,833 $ 10,139,268 $ 53,728 $ 16,841,829
Summary Of Changes In Level 3 Investments Measured At Fair Value On A Recurring Basis	The following table summarizes changes in Level 3 investments measured at fair value on a recurring basis. Quarter Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2019 2018 2019 2018 Equity securities, beginning of period $ 37,988 $ 119,675 $ 53,728 $ 168,809 Purchases — — 500 28,900 Sales (857 ) — (7,726 ) (34,653 ) Net investment gains (losses) on Level 3 investments 7,358 2,418 (2,013 ) (40,963 ) Transfers into Level 3 — — — — Transfers out of Level 3 — — — — Equity securities, end of period $ 44,489 $ 122,093 $ 44,489 $ 122,093

Segment Reporting Disclosures (

Segment Reporting Disclosures (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Company's Segment Disclosures	The following tables summarize the Company's segment disclosures. Quarter Ended September 30, 2019 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures (1) Other (2) Consolidated Gross premium volume $ 1,418,363 $ 226,387 $ — $ — $ 619,742 $ 2,264,492 Net written premiums 1,181,919 187,180 — — 1,285 1,370,384 Earned premiums 1,058,869 240,144 — — 1,019 1,300,032 Losses and loss adjustment expenses: Current accident year (722,172 ) (178,058 ) — — — (900,230 ) Prior accident years 135,029 13,800 — — (733 ) 148,096 Amortization of policy acquisition costs (218,710 ) (61,925 ) — — — (280,635 ) Other operating expenses (171,731 ) (20,436 ) — — (2,417 ) (194,584 ) Underwriting profit (loss) 81,285 (6,475 ) — — (2,131 ) 72,679 Net investment income — — 113,220 162 — 113,382 Net investment gains — — 32,144 — — 32,144 Products revenues — — — 386,708 — 386,708 Services and other revenues — — — 109,373 91,419 200,792 Products expenses — — — (354,404 ) — (354,404 ) Services and other expenses — — — (96,015 ) (57,343 ) (153,358 ) Amortization of intangible assets (3) — — — (10,357 ) (25,338 ) (35,695 ) Segment profit (loss) $ 81,285 $ (6,475 ) $ 145,364 $ 35,467 $ 6,607 $ 262,248 Interest expense (47,465 ) Net foreign exchange gains 53,850 Loss on early extinguishment of debt (6,705 ) Income before income taxes $ 261,928 U.S. GAAP combined ratio (4) 92 % 103 % NM (5) 94 % (1) Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $12.9 million for the quarter ended September 30, 2019 . (2) Other represents the total profit (loss) attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment. (3) Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments. (4) The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums. (5) NM - Ratio is not meaningful Quarter Ended September 30, 2018 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures (1) Other (2) Consolidated Gross premium volume $ 1,248,150 $ 234,360 $ — $ — $ 561,261 $ 2,043,771 Net written premiums 1,021,684 195,349 — — (762 ) 1,216,271 Earned premiums 961,062 225,277 — — (1,016 ) 1,185,323 Losses and loss adjustment expenses: Current accident year (674,529 ) (186,505 ) — — 48 (860,986 ) Prior accident years 111,117 12,681 — — 342 124,140 Amortization of policy acquisition costs (182,857 ) (58,991 ) — — — (241,848 ) Other operating expenses (172,340 ) (26,125 ) — — (1,648 ) (200,113 ) Underwriting profit (loss) 42,453 (33,663 ) — — (2,274 ) 6,516 Net investment income — — 106,164 143 — 106,307 Net investment gains — — 426,075 — — 426,075 Products revenues — — — 362,577 — 362,577 Services and other revenues — — — 106,694 48,973 155,667 Products expenses — — — (341,718 ) — (341,718 ) Services and other expenses — — — (94,924 ) (37,100 ) (132,024 ) Amortization of intangible assets (3) — — — (9,139 ) (18,656 ) (27,795 ) Segment profit (loss) $ 42,453 $ (33,663 ) $ 532,239 $ 23,633 $ (9,057 ) $ 555,605 Interest expense (37,961 ) Net foreign exchange gains 1,383 Income before income taxes $ 519,027 U.S. GAAP combined ratio (4) 96 % 115 % NM (5) 99 % (1) Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $13.0 million for the quarter ended September 30, 2018 . (2) Other represents the total loss attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment. (3) Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments. (4) The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums. (5) NM - Ratio is not meaningful Nine Months Ended September 30, 2019 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures (1) Other (2) Consolidated Gross premium volume $ 3,979,559 $ 963,145 $ — $ — $ 1,823,977 $ 6,766,681 Net written premiums 3,306,447 844,949 — — 1,719 4,153,115 Earned premiums 3,023,865 678,382 — — 1,223 3,703,470 Losses and loss adjustment expenses: Current accident year (1,998,042 ) (456,870 ) — — — (2,454,912 ) Prior accident years 309,324 20,695 — — 6,893 336,912 Amortization of policy acquisition costs (627,318 ) (178,209 ) — — — (805,527 ) Other operating expenses (526,884 ) (58,301 ) — — (2,035 ) (587,220 ) Underwriting profit 180,945 5,697 — — 6,081 192,723 Net investment income — — 338,783 612 — 339,395 Net investment gains — — 1,069,988 — — 1,069,988 Products revenues — — — 1,237,178 — 1,237,178 Services and other revenues — — — 330,653 263,978 594,631 Products expenses — — — (1,098,968 ) — (1,098,968 ) Services and other expenses — — — (290,745 ) (208,015 ) (498,760 ) Amortization of intangible assets (3) — — — (31,674 ) (80,989 ) (112,663 ) Segment profit (loss) $ 180,945 $ 5,697 $ 1,408,771 $ 147,056 $ (18,945 ) $ 1,723,524 Interest expense (129,022 ) Net foreign exchange gains 57,001 Loss on early extinguishment of debt (6,705 ) Income before income taxes $ 1,644,798 U.S. GAAP combined ratio (4) 94 % 99 % NM (5) 95 % (1) Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $40.4 million for the nine months ended September 30, 2019 . (2) Other represents the total profit (loss) attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment. (3) Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments. (4) The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums. (5) NM - Ratio is not meaningful Nine Months Ended September 30, 2018 (dollars in thousands) Insurance Reinsurance Investing Markel Ventures (1) Other (2) Consolidated Gross premium volume $ 3,575,340 $ 935,498 $ — $ — $ 1,577,250 $ 6,088,088 Net written premiums 2,935,789 795,136 — — 754 3,731,679 Earned premiums 2,782,107 702,854 — — (433 ) 3,484,528 Losses and loss adjustment expenses: Current accident year (1,855,190 ) (485,678 ) — — — (2,340,868 ) Prior accident years 369,775 18,135 — — 1,816 389,726 Amortization of policy acquisition costs (554,185 ) (178,818 ) — — — (733,003 ) Other operating expenses (523,239 ) (59,433 ) — — (2,246 ) (584,918 ) Underwriting profit (loss) 219,268 (2,940 ) — — (863 ) 215,465 Net investment income — — 319,253 457 — 319,710 Net investment gains — — 408,326 — — 408,326 Products revenues — — — 1,129,036 — 1,129,036 Services and other revenues — — — 311,048 145,785 456,833 Products expenses — — — (1,062,000 ) — (1,062,000 ) Services and other expenses — — — (273,876 ) (120,435 ) (394,311 ) Amortization of intangible assets (3) — — — (29,332 ) (56,927 ) (86,259 ) Impairment of goodwill and intangible assets — — — (14,904 ) — (14,904 ) Segment profit (loss) $ 219,268 $ (2,940 ) $ 727,579 $ 60,429 $ (32,440 ) $ 971,896 Interest expense (114,722 ) Net foreign exchange gains 65,427 Income before income taxes $ 922,601 U.S. GAAP combined ratio (4) 92 % 100 % NM (5) 94 % (1) Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $38.5 million for the nine months ended September 30, 2018 . (2) Other represents the total loss attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment. (3) Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments. (4) The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums. (5) NM - Ratio is not meaningful
Reconciliation Of Segment Assets To The Company's Consolidated Balance Sheets	The following table reconciles segment assets to the Company's consolidated balance sheets. (dollars in thousands) September 30, 2019 December 31, 2018 Segment assets: Investing $ 21,893,706 $ 19,100,790 Underwriting 6,896,240 6,451,984 Markel Ventures 2,257,878 2,124,506 Total segment assets 31,047,824 27,677,280 Other operations 5,988,372 5,628,983 Total assets $ 37,036,196 $ 33,306,263

Products, Services and Other _2

Products, Services and Other Revenues (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Schedule Of Revenues From Contracts With Customers By Type	The following table disaggregates 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 and comprehensive income . Quarter Ended September 30, 2019 2018 (dollars in thousands) Markel Ventures Other Total Markel Ventures Other Total Products $ 378,421 $ — $ 378,421 $ 350,981 $ — $ 350,981 Services 97,062 17,516 114,578 95,071 7,841 102,912 Investment management — 42,750 42,750 — 18,258 18,258 Total revenues from contracts with customers 475,483 60,266 535,749 446,052 26,099 472,151 Program services and other fronting arrangements — 30,775 30,775 — 22,478 22,478 Other 20,598 378 20,976 23,219 396 23,615 Total $ 496,081 $ 91,419 $ 587,500 $ 469,271 $ 48,973 $ 518,244 Nine Months Ended September 30, 2019 2018 (dollars in thousands) Markel Ventures Other Total Markel Ventures Other Total Products $ 1,198,124 $ — $ 1,198,124 $ 1,095,461 $ — $ 1,095,461 Services 291,617 64,142 355,759 276,548 25,737 302,285 Investment management — 113,738 113,738 — 52,965 52,965 Total revenues from contracts with customers 1,489,741 177,880 1,667,621 1,372,009 78,702 1,450,711 Program services and other fronting arrangements — 84,953 84,953 — 65,810 65,810 Other 78,090 1,145 79,235 68,075 1,273 69,348 Total $ 1,567,831 $ 263,978 $ 1,831,809 $ 1,440,084 $ 145,785 $ 1,585,869
Schedule Of Receivables And Customer Deposits Related To Contracts With Customers	The following table presents receivables and customer deposits related to contracts with customers. (dollars in thousands) September 30, 2019 December 31, 2018 Receivables $ 267,638 $ 247,532 Customer deposits $ 70,984 $ 48,238

Unpaid Losses And Loss Adjust_2

Unpaid Losses And Loss Adjustment Expenses (Tables)	9 Months Ended
	Sep. 30, 2019
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Reconciliation Of Consolidated Reserves For Losses And Loss Adjustment Expenses	The following table presents a reconciliation of consolidated beginning and ending reserves for losses and loss adjustment expenses. Nine Months Ended September 30, (dollars in thousands) 2019 2018 Net reserves for losses and loss adjustment expenses, beginning of year $ 9,214,443 $ 8,964,945 Foreign currency movements (51,544 ) (35,754 ) Adjusted net reserves for losses and loss adjustment expenses, beginning of year 9,162,899 8,929,191 Incurred losses and loss adjustment expenses: Current accident year 2,454,912 2,340,868 Prior accident years (336,942 ) (389,740 ) Total incurred losses and loss adjustment expenses 2,117,970 1,951,128 Payments: Current accident year 410,493 390,245 Prior accident years 1,597,117 1,438,224 Total payments 2,007,610 1,828,469 Effect of foreign currency rate changes (669 ) 368 Net reserves for losses and loss adjustment expenses, end of period 9,272,590 9,052,218 Reinsurance recoverables on unpaid losses 5,165,226 4,836,271 Gross reserves for losses and loss adjustment expenses, end of period $ 14,437,816 $ 13,888,489

Reinsurance (Tables)

Reinsurance (Tables)	9 Months Ended
	Sep. 30, 2019
Reinsurance Disclosures [Abstract]
Effect Of Reinsurance And Retrocessional Reinsurance On Premiums Written And Earned	The following tables summarize the effect of reinsurance and retrocessional reinsurance on premiums written and earned. Quarter Ended September 30, 2019 2018 (dollars in thousands) Direct Assumed Ceded Net Premiums Direct Assumed Ceded Net Premiums Underwriting: Written $ 1,358,243 $ 282,506 $ (271,094 ) $ 1,369,655 $ 1,207,605 $ 274,898 $ (266,788 ) $ 1,215,715 Earned 1,219,103 327,431 (246,965 ) 1,299,569 1,113,763 313,378 (242,120 ) 1,185,021 Program services and other: Written 584,196 39,547 (623,014 ) 729 529,958 31,310 (560,712 ) 556 Earned 576,576 20,399 (596,512 ) 463 480,694 13,046 (493,438 ) 302 Consolidated: Written 1,942,439 322,053 (894,108 ) 1,370,384 1,737,563 306,208 (827,500 ) 1,216,271 Earned $ 1,795,679 $ 347,830 $ (843,477 ) $ 1,300,032 $ 1,594,457 $ 326,424 $ (735,558 ) $ 1,185,323 Nine Months Ended September 30, 2019 2018 (dollars in thousands) Direct Assumed Ceded Net Premiums Direct Assumed Ceded Net Premiums Underwriting: Written $ 3,808,759 $ 1,129,440 $ (786,704 ) $ 4,151,495 $ 3,429,666 $ 1,081,171 $ (781,126 ) $ 3,729,711 Earned 3,510,203 946,648 (754,505 ) 3,702,346 3,221,946 965,586 (703,785 ) 3,483,747 Program services and other: Written 1,754,613 73,869 (1,826,862 ) 1,620 1,537,412 39,839 (1,575,283 ) 1,968 Earned 1,629,659 49,672 (1,678,207 ) 1,124 1,374,443 16,784 (1,390,446 ) 781 Consolidated: Written 5,563,372 1,203,309 (2,613,566 ) 4,153,115 4,967,078 1,121,010 (2,356,409 ) 3,731,679 Earned $ 5,139,862 $ 996,320 $ (2,432,712 ) $ 3,703,470 $ 4,596,389 $ 982,370 $ (2,094,231 ) $ 3,484,528

Leases Leases (Tables)

Leases Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Schedule Of Supplemental Balance Sheet Information Related to Leases [Table Text Block]	The following table summarizes details for the Company's operating leases recorded on the consolidated balance sheet as of September 30, 2019 . (dollars in thousands) Right-of-use lease assets $ 230,474 Lease liabilities $ 254,119 Weighted average remaining lease term 8.6 years Weighted average discount rate 3.4 %
ScheduleofMaturitiesOfOperatingLeasesLiabilities [Table Text Block]	The table below summarizes maturities of the Company’s operating lease liabilities as of September 30, 2019 , which reconciles to total lease liabilities included in other liabilities in the Company’s consolidated balance sheet. Years Ending December 31, (dollars in thousands) 2019 $ 14,250 2020 45,536 2021 42,202 2022 36,483 2023 30,903 2024 and thereafter 124,176 Total lease payments 293,550 Less imputed interest (39,431 ) Total operating lease liabilities $ 254,119

Variable Interest Entities Vari

Variable Interest Entities Variable Interest Entities (Tables)	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Variable Interest Entities [Table Text Block]	The following table presents the balance sheets of the Markel Diversified Fund, which are included on the Company's consolidated balance sheets. (dollars in thousands) September 30, 2019 December 31, 2018 Assets Equity securities: Investment in unconsolidated Markel CATCo Fund $ 16,866 $ 27,547 Other 198 1,082 Total Assets $ 17,064 $ 28,629 Liabilities and Equity Note payable $ 24,875 $ 24,875 Other 65 200 Total Liabilities 24,940 25,075 Total Equity (7,876 ) 3,554 Total Liabilities and Equity $ 17,064 $ 28,629

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2019
Net Income (Loss) per Share [Abstract]
Schedule Of Net Income (Loss) Per Share	Net income per share was determined by dividing adjusted net income to shareholders by the applicable weighted average shares outstanding. Diluted net income per share is computed by dividing adjusted net income to shareholders by the weighted average number of common shares and dilutive potential common shares outstanding during the period. Quarter Ended September 30, Nine Months Ended September 30, (in thousands, except per share amounts) 2019 2018 2019 2018 Net income to shareholders $ 205,637 $ 409,438 $ 1,279,362 $ 623,363 Adjustment of redeemable noncontrolling interests (12,221 ) (12,035 ) 9,464 (6,621 ) Adjusted net income to shareholders $ 193,416 $ 397,403 $ 1,288,826 $ 616,742 Basic common shares outstanding 13,849 13,917 13,870 13,925 Dilutive potential common shares from restricted stock units and restricted stock 15 26 12 24 Diluted shares outstanding 13,864 13,943 13,882 13,949 Basic net income per share $ 13.97 $ 28.56 $ 92.92 $ 44.29 Diluted net income per share $ 13.95 $ 28.50 $ 92.84 $ 44.21

Other Comprehensive Income (Tab

Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2019
Other Comprehensive Income (Loss), Tax [Abstract]
Change In Accumulated Other Comprehensive Income (Loss) By Component, Net Of Taxes And Noncontrolling Interest	The following table presents the change in accumulated other comprehensive income (loss) by component, net of taxes and noncontrolling interests, for the nine months ended September 30, 2019 and 2018 . (dollars in thousands) Unrealized Holding Gains (Losses) on Available-for-Sale Securities Foreign Currency Net Actuarial Pension Loss Total December 31, 2017 $ 2,477,973 $ (74,003 ) $ (58,399 ) $ 2,345,571 Cumulative effect of adoption of ASU No. 2016-01 (2,615,734 ) 2,492 — (2,613,242 ) Cumulative effect of adoption of ASU No. 2018-02 401,539 — — 401,539 January 1, 2018 263,778 (71,511 ) (58,399 ) 133,868 Other comprehensive income (loss) before reclassifications (306,069 ) (19,928 ) 1,741 (324,256 ) Amounts reclassified from accumulated other comprehensive income 5,496 — — 5,496 Total other comprehensive income (loss) (300,573 ) (19,928 ) 1,741 (318,760 ) September 30, 2018 $ (36,795 ) $ (91,439 ) $ (56,658 ) $ (184,892 ) December 31, 2018 $ 48,060 $ (86,652 ) $ (56,058 ) $ (94,650 ) Other comprehensive income (loss) before reclassifications 329,113 (5,929 ) 2,338 325,522 Amounts reclassified from accumulated other comprehensive loss 760 — — 760 Total other comprehensive income (loss) 329,873 (5,929 ) 2,338 326,282 September 30, 2019 $ 377,933 $ (92,581 ) $ (53,720 ) $ 231,632
Summary Of Tax Expense (Benefit) Of Other Comprehensive Income (Loss)	The following table summarizes the tax expense (benefit) associated with each component of other comprehensive income (loss) . Quarter Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2019 2018 2019 2018 Change in net unrealized gains (losses) on available-for-sale investments: Net holding gains (losses) arising during the period $ 13,018 $ (24,047 ) $ 88,168 $ (84,825 ) Reclassification adjustments for net losses included in net income 54 2,810 202 1,461 Change in net unrealized gains (losses) on available-for-sale investments 13,072 (21,237 ) 88,370 (83,364 ) Change in foreign currency translation adjustments — 6,594 — 3,072 Change in net actuarial pension loss 123 135 622 463 Total $ 13,195 $ (14,508 ) $ 88,992 $ (79,829 )
Reclassifications From Accumulated Other Comprehensive Income (Loss) Into Income, By Component	The following table presents the details of amounts reclassified from accumulated other comprehensive income (loss) into income , by component. Quarter Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2019 2018 2019 2018 Unrealized holding gains (losses) on available-for-sale investments: Net realized investment losses, excluding other-than-temporary impairment losses (257 ) (13,383 ) (962 ) (6,957 ) Income taxes 54 2,810 202 1,461 Reclassification of unrealized holding losses, net of taxes $ (203 ) $ (10,573 ) $ (760 ) $ (5,496 ) Net actuarial pension loss: Underwriting, acquisition and insurance expenses $ (585 ) $ (644 ) $ (2,960 ) $ (2,204 ) Income taxes 123 135 622 463 Reclassification of net actuarial pension loss, net of taxes $ (462 ) $ (509 ) $ (2,338 ) $ (1,741 )

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset	$ 230,474	$ 243,700
Operating lease, liability	$ 254,119	$ 264,600

Acquisitions (Narrative) (Detai

Acquisitions (Narrative) (Details) - USD ($) $ in Thousands	Jun. 20, 2019	Nov. 14, 2018	Oct. 01, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Gross premium volume				$ 2,264,492	$ 2,043,771	$ 6,766,681	$ 6,088,088
Ceded premiums written				894,108	$ 827,500	2,613,566	$ 2,356,409
Hagerty Group, LLC [Member]
Business Acquisition [Line Items]
Total purchase consideration	$ 212,500
Brahmin [Member]
Business Acquisition [Line Items]
Percentage acquired			90.00%
Total purchase consideration			$ 192,900
Cash consideration			172,300
Goodwill recognized			63,800
Intangible Assets			93,300
Noncontrolling Interest			19,600
Brahmin [Member] | Customer relationships [Member]
Business Acquisition [Line Items]
Finite-lived intangible assets			$ 57,000
Definite-lived intangible assets, weighted-average amortization period			16 years
Brahmin [Member] | Trade names [Member]
Business Acquisition [Line Items]
Finite-lived intangible assets			$ 35,000
Definite-lived intangible assets, weighted-average amortization period			16 years
Brahmin [Member] | Other intangible assets [Member]
Business Acquisition [Line Items]
Finite-lived intangible assets			$ 1,300
Definite-lived intangible assets, weighted-average amortization period			8 years
Nephila Holdings Limited [Member]
Business Acquisition [Line Items]
Percentage acquired		100.00%
Total purchase consideration		$ 974,400
Cash consideration		974,400
Goodwill recognized		434,200
Intangible Assets		551,000
Goodwill, tax deductible		0
Noncontrolling Interest		15,100
Nephila Holdings Limited [Member] | Investment management agreements [Member]
Business Acquisition [Line Items]
Finite-lived intangible assets		$ 468,000
Definite-lived intangible assets, weighted-average amortization period		17 years
Nephila Holdings Limited [Member] | Broker relationships [Member]
Business Acquisition [Line Items]
Finite-lived intangible assets		$ 32,000
Definite-lived intangible assets, weighted-average amortization period		12 years
Nephila Holdings Limited [Member] | Technology-based intangible assets [Member]
Business Acquisition [Line Items]
Finite-lived intangible assets		$ 27,000
Definite-lived intangible assets, weighted-average amortization period		6 years
Nephila Holdings Limited [Member] | Trade names [Member]
Business Acquisition [Line Items]
Finite-lived intangible assets		$ 24,000
Definite-lived intangible assets, weighted-average amortization period		14 years
Hagerty Group, LLC [Member] | Hagerty Group, LLC [Member]
Business Acquisition [Line Items]
Gross premium volume				120,800		333,700
Ceded premiums written				$ 57,700		$ 159,800

Investments (Narrative) (Detail

Investments (Narrative) (Details) $ in Thousands	Sep. 30, 2019USD ($)securities	Dec. 31, 2018USD ($)securities
Schedule of Investments [Line Items]
Available-for-sale fixed maturity securities in unrealized loss position, number of positions | securities	220	1,005
Available-for-sale securities, estimated fair value	$ 947,715	$ 4,594,664
Available-for-sale securities, gross unrealized holding losses	$ (23,819)	$ (133,989)
Number of available-for-sale fixed maturity securities positions in a continuous unrealized loss position for one year or longer at period end | securities	162	541
Available-for-sale securities, estimated fair value, 12 months or longer	$ 495,569	$ 1,983,912
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(11,065)	(77,504)
Fixed Maturities [Member]
Schedule of Investments [Line Items]
Available-for-sale securities, estimated fair value	832,576	4,397,021
Available-for-sale securities, gross unrealized holding losses	(22,719)	(131,215)
Available-for-sale securities, estimated fair value, 12 months or longer	495,569	1,983,912
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	$ (11,065)	$ (77,504)

Investments (Available-For-Sale

Investments (Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Document Period End Date	Sep. 30, 2019
Available-for-sale fixed maturity investments, amortized cost	$ 9,601,898	$ 9,950,773
Available-for-sale fixed maturity investments, gross unrealized holding gains	624,846	223,630
Available-for-sale fixed maturity investments, gross unrealized holding losses	(22,719)	(131,215)
Available-for-sale fixed maturity investments, estimated fair value	10,204,025	10,043,188
Short-term Investments, Available-for-Sale, Amortized Cost Basis	1,546,129	1,080,027
Short-term Investments, Available-for-Sale, Accumulated Gross Unrealized Gain Before Tax	364	443
Short-term Investments, Available-for-Sale, Accumulated Gross Unrealized Loss Before Tax	(1,100)	(2,774)
Short-term Investments, Available-for-Sale	1,545,393	1,077,696
Investments, Available-for-Sale, Amortized Cost Basis	11,148,027	11,030,800
Investments, Available-for-Sale, Accumulated Gross Unrealized Gain Before Tax	625,210	224,073
Investments, Available-for-Sale, Accumulated Gross Unrealized Loss Before Tax	23,819	133,989
Investments, Available-for-Sale	11,749,418	11,120,884
U.S. Treasury securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity investments, amortized cost	293,954	248,286
Available-for-sale fixed maturity investments, gross unrealized holding gains	3,201	308
Available-for-sale fixed maturity investments, gross unrealized holding losses	(199)	(1,952)
Available-for-sale fixed maturity investments, estimated fair value	296,956	246,642
U.S. government-sponsored enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity investments, amortized cost	331,356	357,765
Available-for-sale fixed maturity investments, gross unrealized holding gains	28,628	5,671
Available-for-sale fixed maturity investments, gross unrealized holding losses	(11)	(4,114)
Available-for-sale fixed maturity investments, estimated fair value	359,973	359,322
Obligations of states, municipalities and political subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity investments, amortized cost	4,047,517	4,285,068
Available-for-sale fixed maturity investments, gross unrealized holding gains	272,703	96,730
Available-for-sale fixed maturity investments, gross unrealized holding losses	(112)	(28,868)
Available-for-sale fixed maturity investments, estimated fair value	4,320,108	4,352,930
Foreign governments [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity investments, amortized cost	1,471,214	1,482,826
Available-for-sale fixed maturity investments, gross unrealized holding gains	158,652	98,356
Available-for-sale fixed maturity investments, gross unrealized holding losses	(14,252)	(21,578)
Available-for-sale fixed maturity investments, estimated fair value	1,615,614	1,559,604
Commercial mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity investments, amortized cost	1,708,617	1,691,572
Available-for-sale fixed maturity investments, gross unrealized holding gains	81,696	3,154
Available-for-sale fixed maturity investments, gross unrealized holding losses	(230)	(44,527)
Available-for-sale fixed maturity investments, estimated fair value	1,790,083	1,650,199
Residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity investments, amortized cost	868,317	886,501
Available-for-sale fixed maturity investments, gross unrealized holding gains	42,015	6,170
Available-for-sale fixed maturity investments, gross unrealized holding losses	(663)	(12,499)
Available-for-sale fixed maturity investments, estimated fair value	909,669	880,172
Asset-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity investments, amortized cost	9,881	19,614
Available-for-sale fixed maturity investments, gross unrealized holding gains	46	7
Available-for-sale fixed maturity investments, gross unrealized holding losses	(3)	(213)
Available-for-sale fixed maturity investments, estimated fair value	9,924	19,408
Corporate bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale fixed maturity investments, amortized cost	871,042	979,141
Available-for-sale fixed maturity investments, gross unrealized holding gains	37,905	13,234
Available-for-sale fixed maturity investments, gross unrealized holding losses	(7,249)	(17,464)
Available-for-sale fixed maturity investments, estimated fair value	$ 901,698	$ 974,911

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	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Document Period End Date	Sep. 30, 2019
Available-for-sale securities, estimated fair value, less than 12 months	$ 452,146	$ 2,610,752
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(12,754)	(56,485)
Available-for-sale securities, estimated fair value, 12 months or longer	495,569	1,983,912
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(11,065)	(77,504)
Available-for-sale securities, estimated fair value	947,715	4,594,664
Available-for-sale securities, gross unrealized holding losses	(23,819)	(133,989)
Short-term Investments, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	115,139	197,643
Short-term Investments, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,100)	(2,774)
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	115,139	197,643
Short-term Investments, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(1,100)	(2,774)
U.S. Treasury securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	7,481	2,922
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(6)	(83)
Available-for-sale securities, estimated fair value, 12 months or longer	81,674	156,352
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(193)	(1,869)
Available-for-sale securities, estimated fair value	89,155	159,274
Available-for-sale securities, gross unrealized holding losses	(199)	(1,952)
U.S. government-sponsored enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	0	88,854
Available-for-sale securities, gross unrealized holding losses, less than 12 months	0	(1,923)
Available-for-sale securities, estimated fair value, 12 months or longer	35,386	96,337
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(11)	(2,191)
Available-for-sale securities, estimated fair value	35,386	185,191
Available-for-sale securities, gross unrealized holding losses	(11)	(4,114)
Obligations of states, municipalities and political subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	1,053	656,573
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(13)	(12,455)
Available-for-sale securities, estimated fair value, 12 months or longer	25,289	453,736
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(99)	(16,413)
Available-for-sale securities, estimated fair value	26,342	1,110,309
Available-for-sale securities, gross unrealized holding losses	(112)	(28,868)
Foreign governments [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	157,525	419,764
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(5,764)	(14,461)
Available-for-sale securities, estimated fair value, 12 months or longer	166,998	84,776
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(8,488)	(7,117)
Available-for-sale securities, estimated fair value	324,523	504,540
Available-for-sale securities, gross unrealized holding losses	(14,252)	(21,578)
Commercial mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	0	653,410
Available-for-sale securities, gross unrealized holding losses, less than 12 months	0	(10,128)
Available-for-sale securities, estimated fair value, 12 months or longer	34,144	709,971
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(230)	(34,399)
Available-for-sale securities, estimated fair value	34,144	1,363,381
Available-for-sale securities, gross unrealized holding losses	(230)	(44,527)
Residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	2,105	276,777
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(9)	(3,685)
Available-for-sale securities, estimated fair value, 12 months or longer	71,317	242,949
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(654)	(8,814)
Available-for-sale securities, estimated fair value	73,422	519,726
Available-for-sale securities, gross unrealized holding losses	(663)	(12,499)
Asset-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	0	1,645
Available-for-sale securities, gross unrealized holding losses, less than 12 months	0	(11)
Available-for-sale securities, estimated fair value, 12 months or longer	2,242	17,030
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(3)	(202)
Available-for-sale securities, estimated fair value	2,242	18,675
Available-for-sale securities, gross unrealized holding losses	(3)	(213)
Corporate bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	168,843	313,164
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(5,862)	(10,965)
Available-for-sale securities, estimated fair value, 12 months or longer	78,519	222,761
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(1,387)	(6,499)
Available-for-sale securities, estimated fair value	247,362	535,925
Available-for-sale securities, gross unrealized holding losses	(7,249)	(17,464)
Total fixed maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	337,007	2,413,109
Available-for-sale securities, gross unrealized holding losses, less than 12 months	(11,654)	(53,711)
Available-for-sale securities, estimated fair value, 12 months or longer	495,569	1,983,912
Available-for-sale securities, gross unrealized holding losses, 12 months or longer	(11,065)	(77,504)
Available-for-sale securities, estimated fair value	832,576	4,397,021
Available-for-sale securities, gross unrealized holding losses	$ (22,719)	$ (131,215)

Investments (Schedule Of Amorti

Investments (Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturity Securities By Contractual Maturity Date) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Document Period End Date	Sep. 30, 2019
Due in one year or less, amortized cost	$ 491,999
Due after one year through five years, amortized cost	1,285,281
Due after five years through ten years, amortized cost	2,081,192
Due after ten years, amortized cost	3,156,611
Amortized cost, sub-total	7,015,083
Total fixed maturities, amortized cost	9,601,898	$ 9,950,773
Due in one year or less, estimated fair value	485,791
Due after one year through five years, estimated fair value	1,310,381
Due after five years through ten years, estimated fair value	2,197,791
Due after ten years, estimated fair value	3,500,386
Estimated fair value, sub-total	7,494,349
Total fixed maturities, estimated fair value	10,204,025	10,043,188
Commercial mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	1,708,617
Total fixed maturities, amortized cost	1,708,617	1,691,572
Fixed maturities, estimated fair value	1,790,083
Total fixed maturities, estimated fair value	1,790,083	1,650,199
Residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	868,317
Total fixed maturities, amortized cost	868,317	886,501
Fixed maturities, estimated fair value	909,669
Total fixed maturities, estimated fair value	909,669	880,172
Asset-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, amortized cost	9,881
Total fixed maturities, amortized cost	9,881	19,614
Fixed maturities, estimated fair value	9,924
Total fixed maturities, estimated fair value	$ 9,924	$ 19,408

Investments (Components Of Net

Investments (Components Of Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Document Period End Date			Sep. 30, 2019
Municipal bonds (tax-exempt)	$ 17,456	$ 19,588	$ 54,167	$ 60,810
Short-term investments, including overnight deposits	14,294	13,719	38,259	36,224
Dividends on equity securities	25,493	21,721	73,486	66,202
Income from equity method investments	366	(3,556)	3,436	(3,268)
Other	797	255	3,971	242
Total investment income	117,408	111,293	351,536	332,646
Investment expenses	(4,026)	(4,986)	(12,141)	(12,936)
Net investment income	113,382	106,307	339,395	319,710
Taxable Municipal Bonds [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Taxable bonds	18,442	18,634	55,634	54,487
Other Taxable Bonds [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Taxable bonds	$ 40,560	$ 40,932	$ 122,583	$ 117,949

Investments (Summary Of Net Inv

Investments (Summary Of Net Investment Gains (Losses) And The Change In Net Unrealized Gains On Investments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Gain (Loss) on Securities [Line Items]
Document Period End Date			Sep. 30, 2019
Realized gains	$ 2,520	$ 4,534	$ 4,532	$ 6,380
Realized losses	(2,370)	(5,030)	(3,768)	(15,464)
Net realized investment gains (losses)	150	(496)	764	(9,084)
Change in fair value of equity securities sold during the period	(345)	151	35,786	10,230
Change in fair value of equity securities held at the end of the period	32,339	426,420	1,033,438	407,180
Change in fair value of equity securities	31,994	426,571	1,069,224	417,410
Net investment gains	32,144	426,075	1,069,988	408,326
Change in net unrealized gains on available-for-sale investments included in other comprehensive income (loss)	92,904	(101,666)	511,307	(383,937)
Sales of fixed maturities [Member]
Gain (Loss) on Securities [Line Items]
Realized gains	856	2,916	2,660	3,748
Realized losses	(198)	(1,003)	(1,109)	(2,652)
Sales of short-term investments [Member]
Gain (Loss) on Securities [Line Items]
Short-term investments, available-for-sale, realized gain	1,540	1,447	1,288	1,624
Short-term investments, available-for-sale, realized loss	(2,172)	(3,997)	(2,659)	(10,044)
Other [Member]
Gain (Loss) on Securities [Line Items]
Realized gains	124	171	584	1,008
Realized losses	0	(30)	0	(2,768)
Fixed Maturities [Member]
Gain (Loss) on Securities [Line Items]
Change in net unrealized gains on available-for-sale investments included in other comprehensive income (loss)	95,170	(103,083)	509,712	(384,176)
Short-term investments [Member]
Gain (Loss) on Securities [Line Items]
Change in net unrealized gains on available-for-sale investments included in other comprehensive income (loss)	$ (2,266)	$ 1,417	$ 1,595	$ 239

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net investment gains (losses)	$ 32,144	$ 426,075	$ 1,069,988	$ 408,326
Equity securities	6,978,874		6,978,874		$ 5,720,945
Fair value, recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, level 1 to level 2 transfers, amount			0	0
Fair value, level 2 to level 1 transfers, amount			0	0
Equity securities	6,978,874		6,978,874		$ 5,720,945
Fair value, nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on a nonrecurring basis	0	0	0	0
Liabilities measured at fair value on a nonrecurring basis	$ 0	$ 0	$ 0	$ 0

Fair Value Measurements (Balanc

Fair Value Measurements (Balances Of Assets Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	$ 10,204,025	$ 10,043,188
Equity securities	6,978,874	5,720,945
Short-term investments, available-for-sale	1,545,393	1,077,696
Total Investments	18,728,292	16,841,829
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	296,956	246,642
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	359,973	359,322
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	4,320,108	4,352,930
Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,615,614	1,559,604
Commercial mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,790,083	1,650,199
Residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	909,669	880,172
Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	9,924	19,408
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	901,698	974,911
Fair value, recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	10,204,025	10,043,188
Equity securities	6,978,874	5,720,945
Short-term investments, available-for-sale	1,545,393	1,077,696
Total Investments	18,728,292	16,841,829
Fair value, recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Equity securities	6,934,385	5,667,217
Short-term investments, available-for-sale	1,444,357	981,616
Total Investments	8,378,742	6,648,833
Fair value, recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	10,204,025	10,043,188
Equity securities	0	0
Short-term investments, available-for-sale	101,036	96,080
Total Investments	10,305,061	10,139,268
Fair value, recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Equity securities	44,489	53,728
Short-term investments, available-for-sale	0	0
Total Investments	44,489	53,728
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	296,956	246,642
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	296,956	246,642
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	359,973	359,322
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	359,973	359,322
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	4,320,108	4,352,930
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	4,320,108	4,352,930
Fair value, recurring [Member] | Obligations of states, municipalities and political subdivisions [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,615,614	1,559,604
Fair value, recurring [Member] | Foreign governments [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Foreign governments [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,615,614	1,559,604
Fair value, recurring [Member] | Foreign governments [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Commercial mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,790,083	1,650,199
Fair value, recurring [Member] | Commercial mortgage-backed securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Commercial mortgage-backed securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	1,790,083	1,650,199
Fair value, recurring [Member] | Commercial mortgage-backed securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	909,669	880,172
Fair value, recurring [Member] | Residential mortgage-backed securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Residential mortgage-backed securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	909,669	880,172
Fair value, recurring [Member] | Residential mortgage-backed securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	9,924	19,408
Fair value, recurring [Member] | Asset-backed securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Asset-backed securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	9,924	19,408
Fair value, recurring [Member] | Asset-backed securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	0	0
Fair value, recurring [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity investments, estimated fair value	901,698	974,911
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	901,698	974,911
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	2,292,441	1,930,539
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	2,247,952	1,876,811
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	44,489	53,728
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	4,686,433	3,790,406
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	4,686,433	3,790,406
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

Fair Value Measurements (Summar

Fair Value Measurements (Summary Of Changes In Level 3 Investments Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, beginning of period	$ 37,988	$ 119,675	$ 53,728	$ 168,809
Purchases	0	0	500	28,900
Sales	(857)	0	(7,726)	(34,653)
Total gains (losses) included in net income (loss)	7,358	2,418	(2,013)	(40,963)
Transfers into level 3	0	0	0	0
Transfers out of level 3	0	0	0	0
Equity securities, end of period	$ 44,489	$ 122,093	$ 44,489	$ 122,093

Segment Reporting Disclosures_2

Segment Reporting Disclosures (Company's Segment Disclosures) (Details) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2019USD ($)		Sep. 30, 2018USD ($)		Sep. 30, 2019USD ($)segment		Sep. 30, 2018USD ($)
Segment Reporting Information [Line Items]
Number of reportable ongoing underwriting segments | segment						2
Gross premium volume		$ 2,264,492		$ 2,043,771		$ 6,766,681		$ 6,088,088
Net written premiums		1,370,384		1,216,271		4,153,115		3,731,679
Earned premiums		1,300,032		1,185,323		3,703,470		3,484,528
Losses and loss adjustment expenses, current accident year		(900,230)		(860,986)		(2,454,912)		(2,340,868)
Losses and loss adjustment expenses, prior accident years		148,096		124,140		336,912		389,726
Amortization of policy acquisition costs		(280,635)		(241,848)		(805,527)		(733,003)
Other operating expenses		(194,584)		(200,113)		(587,220)		(584,918)
Underwriting profit		72,679		6,516		192,723		215,465
Net investment income		113,382		106,307		339,395		319,710
Net investment gains (losses)		32,144		426,075		1,069,988		408,326
Products revenues		386,708		362,577		1,237,178		1,129,036
Services and other revenues		200,792		155,667		594,631		456,833
Products expenses		(354,404)		(341,718)		(1,098,968)		(1,062,000)
Services and other expenses		(153,358)		(132,024)		(498,760)		(394,311)
Amortization of intangible assets		(35,695)	[1]	(27,795)	[2]	(112,663)	[3]	(86,259)	[4]
Impairment of goodwill and intangible assets		0		0		0		(14,904)
Segment profit (loss)		262,248		555,605		1,723,524		971,896
Interest expense		(47,465)		(37,961)		(129,022)		(114,722)
Net foreign exchange losses (gains)		53,850		1,383		57,001		65,427
Loss on early extinguishment of debt		(6,705)		0		(6,705)		0
Income before income taxes		$ 261,928		$ 519,027		$ 1,644,798		$ 922,601
U.S. GAAP combined ratio		94.00%	[5]	99.00%	[6]	95.00%	[7]	94.00%	[8]
Insurance [Member]
Segment Reporting Information [Line Items]
Gross premium volume		$ 1,418,363		$ 1,248,150		$ 3,979,559		$ 3,575,340
Net written premiums		1,181,919		1,021,684		3,306,447		2,935,789
Earned premiums		1,058,869		961,062		3,023,865		2,782,107
Losses and loss adjustment expenses, current accident year		(722,172)		(674,529)		(1,998,042)		(1,855,190)
Losses and loss adjustment expenses, prior accident years		135,029		111,117		309,324		369,775
Amortization of policy acquisition costs		(218,710)		(182,857)		(627,318)		(554,185)
Other operating expenses		(171,731)		(172,340)		(526,884)		(523,239)
Underwriting profit		81,285		42,453		180,945		219,268
Net investment income		0		0		0		0
Net investment gains (losses)		0		0		0		0
Products revenues		0		0		0		0
Services and other revenues		0		0		0		0
Products expenses		0		0		0		0
Services and other expenses		0		0		0		0
Amortization of intangible assets		0	[1]	0	[2]	0	[3]	0	[4]
Impairment of goodwill and intangible assets								0
Segment profit (loss)		$ 81,285		$ 42,453		$ 180,945		$ 219,268
U.S. GAAP combined ratio		92.00%	[5]	96.00%	[6]	94.00%	[7]	92.00%	[8]
Reinsurance [Member]
Segment Reporting Information [Line Items]
Gross premium volume		$ 226,387		$ 234,360		$ 963,145		$ 935,498
Net written premiums		187,180		195,349		844,949		795,136
Earned premiums		240,144		225,277		678,382		702,854
Losses and loss adjustment expenses, current accident year		(178,058)		(186,505)		(456,870)		(485,678)
Losses and loss adjustment expenses, prior accident years		13,800		12,681		20,695		18,135
Amortization of policy acquisition costs		(61,925)		(58,991)		(178,209)		(178,818)
Other operating expenses		(20,436)		(26,125)		(58,301)		(59,433)
Underwriting profit		(6,475)		(33,663)		5,697		(2,940)
Net investment income		0		0		0		0
Net investment gains (losses)		0		0		0		0
Products revenues		0		0		0		0
Services and other revenues		0		0		0		0
Products expenses		0		0		0		0
Services and other expenses		0		0		0		0
Amortization of intangible assets		0	[1]	0	[2]	0	[3]	0	[4]
Impairment of goodwill and intangible assets								0
Segment profit (loss)		$ (6,475)		$ (33,663)		$ 5,697		$ (2,940)
U.S. GAAP combined ratio		103.00%	[5]	115.00%	[6]	99.00%	[7]	100.00%	[8]
Investing [Member]
Segment Reporting Information [Line Items]
Gross premium volume		$ 0		$ 0		$ 0		$ 0
Net written premiums		0		0		0		0
Earned premiums		0		0		0		0
Losses and loss adjustment expenses, current accident year		0		0		0		0
Losses and loss adjustment expenses, prior accident years		0		0		0		0
Amortization of policy acquisition costs		0		0		0		0
Other operating expenses		0		0		0		0
Underwriting profit		0		0		0		0
Net investment income		113,220		106,164		338,783		319,253
Net investment gains (losses)		32,144		426,075		1,069,988		408,326
Products revenues		0		0		0		0
Services and other revenues		0		0		0		0
Products expenses		0		0		0		0
Services and other expenses		0		0		0		0
Amortization of intangible assets		0	[1]	0	[2]	0	[3]	0	[4]
Impairment of goodwill and intangible assets								0
Segment profit (loss)		145,364		532,239		1,408,771		727,579
Markel Ventures [Member]
Segment Reporting Information [Line Items]
Gross premium volume		0	[9]	0	[10]	0	[11]	0	[12]
Net written premiums		0	[9]	0	[10]	0	[11]	0	[12]
Earned premiums		0	[9]	0	[10]	0	[11]	0	[12]
Losses and loss adjustment expenses, current accident year		0	[9]	0	[10]	0	[11]	0	[12]
Losses and loss adjustment expenses, prior accident years		0	[9]	0	[10]	0	[11]	0	[12]
Amortization of policy acquisition costs		0	[9]	0	[10]	0	[11]	0	[12]
Other operating expenses		0	[9]	0	[10]	0	[11]	0	[12]
Underwriting profit		0	[9]	0	[10]	0	[11]	0	[12]
Net investment income		162	[9]	143	[10]	612	[11]	457	[12]
Net investment gains (losses)		0	[9]	0	[10]	0	[11]	0	[12]
Products revenues		386,708	[9]	362,577	[10]	1,237,178	[11]	1,129,036	[12]
Services and other revenues		109,373	[9]	106,694	[10]	330,653	[11]	311,048	[12]
Products expenses		(354,404)	[9]	(341,718)	[10]	(1,098,968)	[11]	(1,062,000)	[12]
Services and other expenses		(96,015)	[9]	(94,924)	[10]	(290,745)	[11]	(273,876)	[12]
Amortization of intangible assets		(10,357)	[1],[9]	(9,139)	[2],[10]	(31,674)	[3],[11]	(29,332)	[4],[12]
Impairment of goodwill and intangible assets								(14,904)
Segment profit (loss)		35,467	[9]	23,633	[10]	147,056	[11]	60,429	[12]
Depreciation expense		(12,900)		(13,000)		(40,400)		(38,500)
Other [Member]
Segment Reporting Information [Line Items]
Gross premium volume		619,742	[13]	561,261	[14]	1,823,977	[15]	1,577,250	[16]
Net written premiums		1,285	[13]	(762)	[14]	1,719	[15]	754	[16]
Earned premiums		1,019	[13]	(1,016)	[14]	1,223	[15]	(433)	[16]
Losses and loss adjustment expenses, current accident year		0	[13]	48	[14]	0	[15]	0	[16]
Losses and loss adjustment expenses, prior accident years		(733)	[13]	342	[14]	6,893	[15]	1,816	[16]
Amortization of policy acquisition costs		0	[13]	0	[14]	0	[15]	0	[16]
Other operating expenses		(2,417)	[13]	(1,648)	[14]	(2,035)	[15]	(2,246)	[16]
Underwriting profit		(2,131)	[13]	(2,274)	[14]	6,081	[15]	(863)	[16]
Net investment income		0	[13]	0	[14]	0	[15]	0	[16]
Net investment gains (losses)		0	[13]	0	[14]	0	[15]	0	[16]
Products revenues		0	[13]	0	[14]	0	[15]	0	[16]
Services and other revenues		91,419	[13]	48,973	[14]	263,978	[15]	145,785	[16]
Products expenses		0	[13]	0	[14]	0	[15]	0	[16]
Services and other expenses		(57,343)	[13]	(37,100)	[14]	(208,015)	[15]	(120,435)	[16]
Amortization of intangible assets		(25,338)	[1],[13]	(18,656)	[2],[14]	(80,989)	[3],[15]	(56,927)	[4],[16]
Impairment of goodwill and intangible assets	[16]							0
Segment profit (loss)		$ 6,607	[13]	$ (9,057)	[14]	$ (18,945)	[15]	$ (32,440)	[12]
U.S. GAAP combined ratio - not meaniningful		NM	[5],[13],[17]	NM	[6],[14],[18]	NM	[7],[15],[19]	NM	[8],[16],[20]
[1]	Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments.
[2]	Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments.
[3]	Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments.
[4]	Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments.
[5]	The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums.
[6]	The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums.
[7]	The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums.
[8]	The U.S. GAAP combined ratio is a measure of underwriting performance and represents the relationship of incurred losses, loss adjustment expenses and underwriting, acquisition and insurance expenses to earned premiums.
[9]	Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $12.9 million for the quarter ended September 30, 2019 .
[10]	Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $13.0 million for the quarter ended September 30, 2018 .
[11]	Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $40.4 million for the nine months ended September 30, 2019 .
[12]	Products expenses and services and other expenses for the Markel Ventures segment include depreciation expense of $38.5 million for the nine months ended September 30, 2018 .
[13]	Other represents the total profit (loss) attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment.
[14]	Other represents the total loss attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment.
[15]	Other represents the total profit (loss) attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment.
[16]	Other represents the total loss attributable to the Company's operations that are not included in a reportable segment as well as any amortization of intangible assets that are not allocated to a reportable segment.
[17]	NM - Ratio is not meaningful
[18]	NM - Ratio is not meaningful
[19]	NM - Ratio is not meaningful
[20]	NM - Ratio is not meaningful

Segment Reporting Disclosures_3

Segment Reporting Disclosures (Reconciliation Of Segment Assets To The Company's Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets	$ 37,036,196	$ 33,306,263
Other [Member]
Segment Reporting Information [Line Items]
Assets	5,988,372	5,628,983
Segment assets [Member]
Segment Reporting Information [Line Items]
Assets	31,047,824	27,677,280
Segment assets [Member] | Investing [Member]
Segment Reporting Information [Line Items]
Assets	21,893,706	19,100,790
Segment assets [Member] | Underwriting [Member]
Segment Reporting Information [Line Items]
Assets	6,896,240	6,451,984
Segment assets [Member] | Markel Ventures [Member]
Segment Reporting Information [Line Items]
Assets	$ 2,257,878	$ 2,124,506

Products, Services and Other _3

Products, Services and Other Revenues (Schedule Of Revenues From Contracts With Customers By Type) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Other revenues	$ 587,500	$ 518,244	$ 1,831,809	$ 1,585,869
Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	535,749	472,151	1,667,621	1,450,711
Products [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	378,421	350,981	1,198,124	1,095,461
Services [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	114,578	102,912	355,759	302,285
Investment management [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	42,750	18,258	113,738	52,965
Program services and other fronting arrangements [Member]
Disaggregation of Revenue [Line Items]
Other revenues	30,775	22,478	84,953	65,810
Other [Member]
Disaggregation of Revenue [Line Items]
Other revenues	20,976	23,615	79,235	69,348
Other [Member]
Disaggregation of Revenue [Line Items]
Other revenues	91,419	48,973	263,978	145,785
Other [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	60,266	26,099	177,880	78,702
Other [Member] | Products [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	0	0	0	0
Other [Member] | Services [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	17,516	7,841	64,142	25,737
Other [Member] | Investment management [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	42,750	18,258	113,738	52,965
Other [Member] | Program services and other fronting arrangements [Member]
Disaggregation of Revenue [Line Items]
Other revenues	30,775	22,478	84,953	65,810
Other [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Other revenues	378	396	1,145	1,273
Markel Ventures [Member]
Disaggregation of Revenue [Line Items]
Other revenues	496,081	469,271	1,567,831	1,440,084
Markel Ventures [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	475,483	446,052	1,489,741	1,372,009
Markel Ventures [Member] | Products [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	378,421	350,981	1,198,124	1,095,461
Markel Ventures [Member] | Services [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	97,062	95,071	291,617	276,548
Markel Ventures [Member] | Investment management [Member] | Revenue from contracts with customers [Member]
Disaggregation of Revenue [Line Items]
Other revenues	0	0	0	0
Markel Ventures [Member] | Program services and other fronting arrangements [Member]
Disaggregation of Revenue [Line Items]
Other revenues	0	0	0	0
Markel Ventures [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Other revenues	$ 20,598	$ 23,219	$ 78,090	$ 68,075

Products, Services and Other _4

Products, Services and Other Revenues (Schedule Of Receivables And Customer Deposits Related To Contracts With Customers) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Receivables and Customer Deposits [Line Items]
Receivables	$ 1,930,394	$ 1,692,526
Contracts with customers [Member]
Receivables and Customer Deposits [Line Items]
Receivables	267,638	247,532
Customer deposits	$ 70,984	$ 48,238

Unpaid Losses And Loss Adjust_3

Unpaid Losses And Loss Adjustment Expenses (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable (adverse) development on prior years' loss reserves			$ 336,942	$ 389,740
Net losses and loss adjustment expenses	$ 900,230	$ 860,986	2,454,912	2,340,868
Reinsurance recoverables	$ 94,400	$ 171,100	443,800	394,900
Gen liab, workers comp and professional liab lines Insurance segment, and aviation, auto and whole account Reinsurance segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable (adverse) development on prior years' loss reserves			(257,700)
Gen liab, workers comp, marine & energy and prof liab Insurance segment and credit and surety and marine and energy Reinsurance segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable (adverse) development on prior years' loss reserves				(312,200)
2019 Catastrophes [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss adjustment expenses, net of assumed reinstatement premiums			42,600
Net losses and loss adjustment expenses			45,100
Net assumed reinstatement premiums			(2,500)
Reinsurance recoverables			$ 4,800
2018 Catastrophes [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss adjustment expenses, net of assumed reinstatement premiums				75,700
Net losses and loss adjustment expenses				77,800
Net assumed reinstatement premiums				(2,100)
Reinsurance recoverables				$ 28,600

Unpaid Losses And Loss Adjust_4

Unpaid Losses And Loss Adjustment Expenses (Reconciliation Of Consolidated Reserves For Losses And Loss Adjustment Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Net reserves for losses and loss adjustment expenses, beginning of year			$ 9,214,443	$ 8,964,945
Foreign currency movements	$ (51,544)	$ (35,754)	(51,544)	(35,754)
Adjusted net reserves for losses and loss adjustment expenses, beginning of year			9,162,899	8,929,191
Net losses and loss adjustment expenses	900,230	860,986	2,454,912	2,340,868
Incurred losses and loss adjustment expenses, prior accident years			(336,942)	(389,740)
Total incurred losses and loss adjustment expenses			2,117,970	1,951,128
Payments, current accident year			410,493	390,245
Payments, prior accident years			1,597,117	1,438,224
Total payments			2,007,610	1,828,469
Effect of foreign currency rate changes			(669)	368
Net reserves for losses and loss adjustment expenses, end of period	9,272,590	9,052,218	9,272,590	9,052,218
Reinsurance recoverable on unpaid losses	5,165,226	4,836,271	5,165,226	4,836,271
Gross reserves for losses and loss adjustment expenses, end of period	$ 14,437,816	$ 13,888,489	$ 14,437,816	$ 13,888,489

Reinsurance (Narrative) (Detail

Reinsurance (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Percentage of ceded earned premiums to gross earned premiums	39.00%	38.00%	40.00%	38.00%
Percentage of assumed earned premiums to net earned premiums	27.00%	28.00%	27.00%	28.00%
Reinsurance recoverables	$ 94.4	$ 171.1	$ 443.8	$ 394.9
Program services [Member]
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance recoverables	$ 412.7	$ 329.9	$ 1,100	$ 959.5

Reinsurance (Effect Of Reinsura

Reinsurance (Effect Of Reinsurance And Retrocessional Reinsurance On Premiums Written And Earned) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Effects of Reinsurance [Line Items]
Direct premiums written	$ 1,942,439	$ 1,737,563	$ 5,563,372	$ 4,967,078
Direct premiums earned	1,795,679	1,594,457	5,139,862	4,596,389
Assumed premiums written	322,053	306,208	1,203,309	1,121,010
Assumed premiums earned	347,830	326,424	996,320	982,370
Ceded premiums written	(894,108)	(827,500)	(2,613,566)	(2,356,409)
Ceded premiums earned	(843,477)	(735,558)	(2,432,712)	(2,094,231)
Net premiums written	1,370,384	1,216,271	4,153,115	3,731,679
Net premiums earned	1,300,032	1,185,323	3,703,470	3,484,528
Underwriting [Member]
Effects of Reinsurance [Line Items]
Direct premiums written	1,358,243	1,207,605	3,808,759	3,429,666
Direct premiums earned	1,219,103	1,113,763	3,510,203	3,221,946
Assumed premiums written	282,506	274,898	1,129,440	1,081,171
Assumed premiums earned	327,431	313,378	946,648	965,586
Ceded premiums written	(271,094)	(266,788)	(786,704)	(781,126)
Ceded premiums earned	(246,965)	(242,120)	(754,505)	(703,785)
Net premiums written	1,369,655	1,215,715	4,151,495	3,729,711
Net premiums earned	1,299,569	1,185,021	3,702,346	3,483,747
Program services and other [Member]
Effects of Reinsurance [Line Items]
Direct premiums written	584,196	529,958	1,754,613	1,537,412
Direct premiums earned	576,576	480,694	1,629,659	1,374,443
Assumed premiums written	39,547	31,310	73,869	39,839
Assumed premiums earned	20,399	13,046	49,672	16,784
Ceded premiums written	(623,014)	(560,712)	(1,826,862)	(1,575,283)
Ceded premiums earned	(596,512)	(493,438)	(1,678,207)	(1,390,446)
Net premiums written	729	556	1,620	1,968
Net premiums earned	$ 463	$ 302	$ 1,124	$ 781

Life and Annuity Benefits Lif_2

Life and Annuity Benefits Life and Annuity Benefits (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Liability for Future Policy Benefit, before Reinsurance [Abstract]
Increase in life and annuity benefits	$ 31.3	$ 0	$ 93.1	$ 0
Cumulative adjustment to life and annuity benefits	$ 93.1		$ 93.1

Senior Long-Term Debt and Oth_2

Senior Long-Term Debt and Other Debt Senior Long-Term Debt and Other Debt (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Debt instrument, fair value disclosure	$ 4,257,000,000		$ 4,257,000,000			$ 3,030,000,000
Line of credit facility, expiration date	Apr. 10, 2024
Loss on early extinguishment of debt	$ 6,705,000	$ 0	6,705,000	$ 0
Revolving credit facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	300,000,000		300,000,000		$ 300,000,000
Line of credit facility borrowing capacity increase			200,000,000
Long-term line of credit	0		0			$ 0
Secured letters of credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 200,000,000		$ 200,000,000

Senior Long-Term Debt and Oth_3

Senior Long-Term Debt and Other Debt Senior Long-Term Debt (Narrative) (Details) - USD ($) $ in Thousands	Oct. 18, 2019	Sep. 17, 2019	May 20, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Debt instrument, fair value disclosure				$ 4,257,000		$ 4,257,000		$ 3,030,000
Loss on early extinguishment of debt				$ 6,705	$ 0	$ 6,705	$ 0
Five point zero percent unsecured senior notes due May 20 2049 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 600,000
Debt Instrument, interest rate, stated percentage			5.00%
Proceeds from debt, net of issuance costs			$ 592,200
Seven point one two five percent unsecured senior notes due September 30 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, interest rate, stated percentage				7.125%		7.125%
Debt instrument, fair value disclosure								$ 234,800
Three point three five percent unsecured senior notes due September 17 2029 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 300,000
Debt Instrument, interest rate, stated percentage		3.35%
Proceeds from debt, net of issuance costs		$ 297,500
Four point one five percent unsecured senior notes due September 17 2050 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 500,000
Debt Instrument, interest rate, stated percentage		4.15%
Proceeds from debt, net of issuance costs		$ 494,500
Six point two five percent unsecured senior notes due September 30, 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, interest rate, stated percentage				6.25%		6.25%
Early repayment of senior debt		130,100
Debt instrument, repurchased face amount				$ 125,200		$ 125,200
Debt instrument, fair value disclosure				$ 224,800		$ 224,800
Five point three five percent unsecured senior notes due June 1, 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, interest rate, stated percentage				5.35%		5.35%
Early repayment of senior debt		$ 103,000
Debt instrument, repurchased face amount				$ 97,800		$ 97,800
Debt instrument, fair value disclosure				$ 152,200		$ 152,200
Subsequent event [Member] | Six point two five percent unsecured senior notes due September 30, 2020 [Member]
Debt Instrument [Line Items]
Early repayment of senior debt	$ 233,400
Subsequent event [Member] | Five point three five percent unsecured senior notes due June 1, 2021 [Member]
Debt Instrument [Line Items]
Early repayment of senior debt	$ 160,200

Leases Leases (Narrative) (Deta

Leases Leases (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Lease of facilities and furniture maximum duration		15 years
Operating lease, right-of-use asset	$ 230,474	$ 230,474	$ 243,700
Operating leases, rent expense, net	$ 14,000	$ 47,200
Operating lease, weighted average discount rate, percent	3.40%	3.40%
Operating lease, weighted average remaining lease term	8 years 7 months 6 days	8 years 7 months 6 days
Lease liability payments due within twelve months	$ 14,250	$ 14,250
Lessee, operating lease, liability, payments, due year two	45,536	45,536
Lessee, operating lease, liability, payments, due year three	42,202	42,202
Lessee, operating lease, liability, payments, due year four	36,483	36,483
Lessee, operating lease, liability, payments, due year five	30,903	30,903
Lessee, operating lease, liability, payments, due after year five	124,176	124,176
Lessee, operating lease, liability, payments, due	293,550	293,550
Lessee, operating lease, liability, undiscounted excess amount	(39,431)	(39,431)
Operating lease, liability	$ 254,119	$ 254,119	$ 264,600

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Effective tax rate	22.00%	32.00%
Provision for deferred U.S. income taxes		$ 102
Effective tax rate attributable to U.K. subsidiaries being taxed as domestic corporations		(11.00%)
Estimated annual effective tax rate	21.00%	20.00%
Income tax examination, year under examination	2017

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Variable Interest Entity [Line Items]
Investment management fees earned by the Company from unconsolidated Funds	$ 587,500	$ 518,244	$ 1,831,809	$ 1,585,869
Equity securities	$ 6,978,874		$ 6,978,874		$ 5,720,945
Unconsolidated Markel CATCo Fund 1 [Member]
Variable Interest Entity [Line Items]
Percentage of total assets of the Markel Diversified Fund invested in one of the unconsolidated Funds	3.00%		3.00%		2.00%
Unconsolidated Markel CATCo Fund 2 [Member]
Variable Interest Entity [Line Items]
Variable interest entity, consolidated, carrying amount, investment in one of the unconsolidated funds	$ 27,600		$ 27,600		$ 26,200
Revenue from contracts with customers [Member]
Variable Interest Entity [Line Items]
Investment management fees earned by the Company from unconsolidated Funds	535,749	472,151	1,667,621	1,450,711
Other [Member]
Variable Interest Entity [Line Items]
Investment management fees earned by the Company from unconsolidated Funds	91,419	48,973	263,978	145,785
Other [Member] | Revenue from contracts with customers [Member]
Variable Interest Entity [Line Items]
Investment management fees earned by the Company from unconsolidated Funds	60,266	26,099	177,880	78,702
Investment management [Member] | Revenue from contracts with customers [Member]
Variable Interest Entity [Line Items]
Investment management fees earned by the Company from unconsolidated Funds	42,750	18,258	113,738	52,965
Investment management [Member] | Other [Member] | Revenue from contracts with customers [Member]
Variable Interest Entity [Line Items]
Investment management fees earned by the Company from unconsolidated Funds	42,750	18,258	113,738	52,965
Unconsolidated Markel CATCo Funds [Member]
Variable Interest Entity [Line Items]
Investment management fees earned by the Company from unconsolidated Funds	10,000	$ 18,300	28,100	$ 53,000
Net assets of unconsolidated variable interest entities under management	$ 3,000,000		$ 3,000,000

Variable Interest Entities Sche

Variable Interest Entities Schedule of Variable Interest Entities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Other assets	$ 1,879,695	$ 1,383,823
Other liabilities	2,247,179	1,796,036
Markel Diversified Fund [Member]
Variable Interest Entity [Line Items]
Variable interest entity, consolidated, carrying amount, investment in one of the unconsolidated funds	16,866	27,547
Other assets	198	1,082
Variable interest entity, consolidated, carrying amount, Assets	17,064	28,629
Other liabilities	65	200
Variable interest entity, consolidated, carrying amount, Liabilities	24,940	25,075
Variable interest entity, consolidated, carrying amount, Equity	(7,876)	3,554
Variable interest entity, consolidated, carrying amount, Liabilities and Equity	17,064	28,629
Other debt [Member] | Markel Diversified Fund [Member]
Variable Interest Entity [Line Items]
Variable interest entity, consolidated, carrying amount, Note payable	$ 24,875	$ 24,875

Related Party Transactions Re_2

Related Party Transactions Related Party Transactions (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Gross premium volume	$ 2,264,492	$ 2,043,771	$ 6,766,681	$ 6,088,088
Ceded premiums written	894,108	827,500	2,613,566	2,356,409
Reinsurance recoverables	5,372,156		5,372,156		$ 5,221,947
Nephila Funds and Nephila Reinsurers [Member]
Related Party Transaction [Line Items]
Revenues attributable to management contracts with Nephila Funds and the Nephila Reinsurers	42,700		124,700
Syndicate 2357 and certain other Nephila Reinsurers [Member]
Related Party Transaction [Line Items]
Gross premium volume	126,400		360,600
Ceded premiums written	126,400		360,600
Reinsurance recoverables	229,800		229,800		$ 179,800
Markel CATCo Re. related party transaction 2 [Member]
Related Party Transaction [Line Items]
Ceding fees			8,800
Ceding fees, earned	2,200		6,600
Loss exposure on certain contracts	191,600		191,600
Markel CATCo Re. related party transaction 1 [Member]
Related Party Transaction [Line Items]
Gross written premiums on behalf of Markel CATCo Re.	100	1,000	5,500	10,600
Ceded premiums on behalf of Markel CATCo Re.	$ 100	$ 1,000	$ 5,500	$ 10,600

Shareholders' Equity (Narrative

Shareholders' Equity (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares repurchased | shares	77,991
Stock repurchased value	$ 81.1
August 2019 share repurchase program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program, authorized amount	$ 300
Number of common stock shares repurchased | shares	4,620
Stock repurchased value	$ 5.4
May 2018 share repurchase program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares repurchased | shares	73,371
Stock repurchased value	$ 75.8
Cumulative stock repurchased shares | shares	93,036
Cumulative stock repurchased value	$ 97.2

Shareholders' Equity (Schedule

Shareholders' Equity (Schedule Of Net Income (Loss) Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Line Items]
Net income to shareholders	$ 205,637	$ 409,438	$ 1,279,362	$ 623,363
Adjustment of redeemable noncontrolling interests	(12,221)	(12,035)	9,464	(6,621)
Adjusted net income to shareholders	$ 193,416	$ 397,403	$ 1,288,826	$ 616,742
Basic common shares outstanding	13,849	13,917	13,870	13,925
Diluted shares outstanding	13,864	13,943	13,882	13,949
Basic net income per share	$ 13.97	$ 28.56	$ 92.92	$ 44.29
Diluted net income per share	$ 13.95	$ 28.50	$ 92.84	$ 44.21
Restricted Stock Units (RSUs) [Member]
Earnings Per Share [Line Items]
Dilutive potential common shares	15	26	12	24

Other Comprehensive Income Othe

Other Comprehensive Income Other Comprehensive Income (Narrative) (Details) $ in Thousands	Jan. 01, 2018USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes	$ (2,613,242)
Cumulative effect of adoption of ASU No 2018-02	401,539
Unrealized holding gains on available-for-sale securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes	(2,615,734)
Cumulative effect of adoption of ASU No 2018-02	$ 401,539

Other Comprehensive Income (Cha

Other Comprehensive Income (Change In Accumulated Other Comprehensive Income (Loss) By Component, Net Of Taxes And Noncontrolling Interest) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2018
Accumulated Other Comprehensive Income [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes			$ (2,613,242)
Cumulative effect of adoption of ASU No 2018-02			401,539
Accumulated other comprehensive income, beginning balance	$ (94,650)	$ 2,345,571
Other comprehensive income (loss) before reclassifications	325,522	(324,256)
Amounts reclassified from accumulated other comprehensive income (loss)	760	5,496
Total other comprehensive income (loss)	326,282	(318,760)
Accumulated other comprehensive income, ending balance	231,632	(184,892)
Accumulated other comprehensive income (loss), net of tax, adjusted			133,868
Unrealized Holding Gains On Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes			(2,615,734)
Cumulative effect of adoption of ASU No 2018-02			401,539
Accumulated other comprehensive income, beginning balance	48,060	2,477,973
Other comprehensive income (loss) before reclassifications	329,113	(306,069)
Amounts reclassified from accumulated other comprehensive income (loss)	760	5,496
Total other comprehensive income (loss)	329,873	(300,573)
Accumulated other comprehensive income, ending balance	377,933	(36,795)
Accumulated other comprehensive income (loss), net of tax, adjusted			263,778
Foreign Currency [Member]
Accumulated Other Comprehensive Income [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes			2,492
Cumulative effect of adoption of ASU No 2018-02			0
Accumulated other comprehensive income, beginning balance	(86,652)	(74,003)
Other comprehensive income (loss) before reclassifications	(5,929)	(19,928)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	(5,929)	(19,928)
Accumulated other comprehensive income, ending balance	(92,581)	(91,439)
Accumulated other comprehensive income (loss), net of tax, adjusted			(71,511)
Net Actuarial Pension Loss [Member]
Accumulated Other Comprehensive Income [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes			0
Cumulative effect of adoption of ASU No 2018-02			0
Accumulated other comprehensive income, beginning balance	(56,058)	(58,399)
Other comprehensive income (loss) before reclassifications	2,338	1,741
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	2,338	1,741
Accumulated other comprehensive income, ending balance	$ (53,720)	$ (56,658)
Accumulated other comprehensive income (loss), net of tax, adjusted			$ (58,399)

Other Comprehensive Income (Sum

Other Comprehensive Income (Summary Of Tax Expense (Benefit) Of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other Comprehensive Income (Loss), Tax [Abstract]
Net holding gains (losses) arising during the period	$ 13,018	$ (24,047)	$ 88,168	$ (84,825)
Reclassification adjustments for net losses included in net income (loss)	54	2,810	202	1,461
Change in net unrealized gains (losses) on available-for-sale investments	13,072	(21,237)	88,370	(83,364)
Change in foreign currency translation adjustments	0	6,594	0	3,072
Change in net actuarial pension loss	123	135	622	463
Total	$ 13,195	$ (14,508)	$ 88,992	$ (79,829)

Other Comprehensive Income (Rec

Other Comprehensive Income (Reclassifications From Accumulated Other Comprehensive Income (Loss) Into Income, By Component) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Net realized investment losses	$ 150	$ (496)	$ 764	$ (9,084)
Income Before Income Taxes	261,928	519,027	1,644,798	922,601
Underwriting, acquisition and insurance expenses	(475,219)	(441,961)	(1,392,747)	(1,317,921)
Income taxes	(57,975)	(109,999)	(356,849)	(299,580)
Net Income	203,953	409,028	1,287,949	623,021
Reclassification out of accumulated other comprehensive income [Member] | Unrealized holding gains on available-for-sale securities [Member]
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Net realized investment losses	(257)	(13,383)	(962)	(6,957)
Income taxes	54	2,810	202	1,461
Net Income	(203)	(10,573)	(760)	(5,496)
Reclassification out of accumulated other comprehensive income [Member] | Net actuarial pension loss [Member]
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Underwriting, acquisition and insurance expenses	(585)	(644)	(2,960)	(2,204)
Income taxes	123	135	622	463
Net Income	$ (462)	$ (509)	$ (2,338)	$ (1,741)

Commitments and Contingencies (

Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Feb. 21, 2019	Dec. 31, 2018
Markel Ventures [Member] | Industrial products [Member]
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss	$ 21.4		$ 33.5
Anthony Belisle v. Markel CATCo Investment Management Ltd and Markel Corp. [Member]
Loss Contingencies [Line Items]
Asserted claims		$ 66
Alissa Fredricks v. Markel CATCo Investment Management Ltd. and Markel Corp. [Member]
Loss Contingencies [Line Items]
Asserted claims		$ 7.5
Lodgepine Fund Limited [Member]
Loss Contingencies [Line Items]
Other commitment	$ 100

Subsequent Events Subsequent _2

Subsequent Events Subsequent Events (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 29, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Subsequent Event [Line Items]
Policyholder benefits and claims incurred, net, property, casualty and liability		$ 752,134	$ 736,846	$ 2,118,000	$ 1,951,142
Minimum [Member] | Typhoon Hagibis [Member] | Subsequent event [Member]
Subsequent Event [Line Items]
Policyholder benefits and claims incurred, net, property, casualty and liability	$ 60,000
Maximum [Member] | Typhoon Hagibis [Member] | Subsequent event [Member]
Subsequent Event [Line Items]
Policyholder benefits and claims incurred, net, property, casualty and liability	$ 120,000

Uncategorized Items - mkl093020

Label	Element	Value
AOCI Attributable to Parent [Member]
Cumulative Effect of Adoption of ASU No 2014-09, Net of Taxes	mkl_CumulativeEffectofAdoptionofASUNo201409NetofTaxes	$ 0
Cumulative Effect of Adoption of ASU No 2018-02	mkl_CumulativeEffectofAdoptionofASUNo201802	401,539,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	133,868,000
Cumulative Effect of Adoption of ASU No. 2016-01, Net of Tax	mkl_CumulativeEffectofAdoptionofASUNo.201601NetofTax	$ (2,613,242,000)
Common Stock [Member]
Shares, Issued	us-gaap_SharesIssued	13,904,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	$ 3,381,834,000
Noncontrolling Interest [Member]
Cumulative Effect of Adoption of ASU No 2014-09, Net of Taxes	mkl_CumulativeEffectofAdoptionofASUNo201409NetofTaxes	0
Cumulative Effect of Adoption of ASU No 2018-02	mkl_CumulativeEffectofAdoptionofASUNo201802	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	(2,567,000)
Cumulative Effect of Adoption of ASU No. 2016-01, Net of Tax	mkl_CumulativeEffectofAdoptionofASUNo.201601NetofTax	0
Parent [Member]
Cumulative Effect of Adoption of ASU No 2014-09, Net of Taxes	mkl_CumulativeEffectofAdoptionofASUNo201409NetofTaxes	325,000
Cumulative Effect of Adoption of ASU No 2018-02	mkl_CumulativeEffectofAdoptionofASUNo201802	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	9,504,473,000
Cumulative Effect of Adoption of ASU No. 2016-01, Net of Tax	mkl_CumulativeEffectofAdoptionofASUNo.201601NetofTax	0
Retained Earnings [Member]
Cumulative Effect of Adoption of ASU No 2014-09, Net of Taxes	mkl_CumulativeEffectofAdoptionofASUNo201409NetofTaxes	325,000
Cumulative Effect of Adoption of ASU No 2018-02	mkl_CumulativeEffectofAdoptionofASUNo201802	(401,539,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	5,988,771,000
Cumulative Effect of Adoption of ASU No. 2016-01, Net of Tax	mkl_CumulativeEffectofAdoptionofASUNo.201601NetofTax	2,613,242,000
Redeemable Noncontrolling Interests, Temporary Equity [Member]
Cumulative Effect of Adoption of ASU No 2014-09, Net of Taxes	mkl_CumulativeEffectofAdoptionofASUNo201409NetofTaxes	0
Cumulative Effect of Adoption of ASU No 2018-02	mkl_CumulativeEffectofAdoptionofASUNo201802	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	166,269,000
Cumulative Effect of Adoption of ASU No. 2016-01, Net of Tax	mkl_CumulativeEffectofAdoptionofASUNo.201601NetofTax	0
Total Equity [Member]
Cumulative Effect of Adoption of ASU No 2014-09, Net of Taxes	mkl_CumulativeEffectofAdoptionofASUNo201409NetofTaxes	325,000
Cumulative Effect of Adoption of ASU No 2018-02	mkl_CumulativeEffectofAdoptionofASUNo201802	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	9,501,906,000
Cumulative Effect of Adoption of ASU No. 2016-01, Net of Tax	mkl_CumulativeEffectofAdoptionofASUNo.201601NetofTax	$ 0