Markel (MKL) 10-Q 2 Aug 16 2016 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Jul. 26, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
Entity Registrant Name	MARKEL CORP
Entity Central Index Key	1,096,343
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		13,990,839

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
ASSETS
Fixed maturities (amortized cost of $9,590,337 in 2016 and $9,038,158 in 2015)	$ 10,399,629	$ 9,394,468
Equity securities (cost of $2,390,184 in 2016 and $2,208,834 in 2015)	4,395,569	4,074,475
Short-term investments (estimated fair value approximates cost)	1,995,491	1,642,261
Total Investments	16,790,689	15,111,204
Cash and cash equivalents	2,007,938	2,630,009
Restricted cash and cash equivalents	353,900	440,132
Receivables	1,427,092	1,113,703
Reinsurance recoverable on unpaid losses	2,038,687	2,016,665
Reinsurance recoverable on paid losses	57,940	50,123
Deferred policy acquisition costs	415,700	352,756
Prepaid reinsurance premiums	362,865	322,362
Goodwill	1,167,861	1,167,844
Intangible assets	753,191	792,372
Other assets	959,765	941,945
Total Assets	26,335,628	24,939,115
LIABILITIES AND EQUITY
Unpaid losses and loss adjustment expenses	10,199,899	10,251,953
Life and annuity benefits	1,152,676	1,123,275
Unearned premiums	2,529,540	2,166,105
Payables to insurance and reinsurance companies	260,599	224,921
Senior long-term debt and other debt (estimated fair value of $2,842,000 in 2016 and $2,403,000 in 2015)	2,602,432	2,239,271
Other liabilities	1,078,708	1,030,023
Total Liabilities	17,823,854	17,035,548
Redeemable noncontrolling interests	66,201	62,958
Commitments and contingencies
Shareholders' equity:
Common stock	3,360,830	3,342,357
Retained earnings	3,355,262	3,137,285
Accumulated other comprehensive income	1,722,277	1,354,508
Total Shareholders' Equity	8,438,369	7,834,150
Noncontrolling interests	7,204	6,459
Total Equity	8,445,573	7,840,609
Total Liabilities and Equity	$ 26,335,628	$ 24,939,115

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 9,590,337	$ 9,038,158
Equity securities, cost	2,390,184	2,208,834
Senior long-term debt and other debt, estimated fair value	$ 2,842,000	$ 2,403,000

Consolidated Statements Of Inco

Consolidated Statements Of Income And Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
OPERATING REVENUES
Earned premiums	$ 950,859	$ 957,557	$ 1,908,545	$ 1,901,207
Net investment income	94,996	90,586	186,290	183,461
Other-than-temporary impairment losses	(3,675)	0	(12,080)	(5,092)
Net realized investment gains, excluding other-than-temporary impairment losses	20,916	6,105	50,500	16,768
Net realized investment gains	17,241	6,105	38,420	11,676
Other revenues	312,841	250,357	618,864	510,415
Total Operating Revenues	1,375,937	1,304,605	2,752,119	2,606,759
OPERATING EXPENSES
Losses and loss adjustment expenses	511,556	536,194	985,520	983,189
Underwriting, acquisition and insurance expenses	375,580	379,652	740,268	720,337
Amortization of intangible assets	17,204	16,949	34,464	31,589
Other expenses	277,909	242,236	553,002	473,237
Total Operating Expenses	1,182,249	1,175,031	2,313,254	2,208,352
Operating Income	193,688	129,574	438,865	398,407
Interest expense	33,697	29,288	64,538	58,600
Loss on early extinguishment of debt	44,100	0	44,100	0
Income Before Income Taxes	115,891	100,286	330,227	339,807
Income tax expense	35,218	7,833	85,908	53,348
Net Income	80,673	92,453	244,319	286,459
Net income attributable to noncontrolling interests	1,876	1,084	5,152	4,098
Net Income to Shareholders	78,797	91,369	239,167	282,361
OTHER COMPREHENSIVE INCOME (LOSS)
Net holding gains (losses) arising during the period	149,406	(230,142)	388,296	(109,120)
Change in unrealized other-than-temporary impairment losses on fixed maturities arising during the period	44	(48)	(23)	119
Reclassification adjustments for net gains included in net income	(10,567)	(4,984)	(23,550)	(14,037)
Change in net unrealized gains on investments, net of taxes	138,883	(235,174)	364,723	(123,038)
Change in foreign currency translation adjustments, net of taxes	(8,121)	10,385	2,208	(11,429)
Change in net actuarial pension loss, net of taxes	394	469	857	932
Total Other Comprehensive Income (Loss)	131,156	(224,320)	367,788	(133,535)
Comprehensive Income (Loss)	211,829	(131,867)	612,107	152,924
Comprehensive income attributable to noncontrolling interests	1,887	1,058	5,171	4,042
Comprehensive Income (Loss) to Shareholders	$ 209,942	$ (132,925)	$ 606,936	$ 148,882
NET INCOME PER SHARE
Basic (in dollars per share)	$ 5.44	$ 6.76	$ 16.65	$ 20.33
Diluted (in dollars per share)	$ 5.41	$ 6.72	$ 16.55	$ 20.21

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Equity - USD ($) shares in Thousands, $ in Thousands	Total	Total Equity [Member]	Total Shareholders' Equity [Member]	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Noncontrolling Interests [Member]	Redeemable Noncontrolling Interests [Member]
Balance at Dec. 31, 2014		$ 7,602,002	$ 7,594,818	$ 3,308,395	$ 2,581,866	$ 1,704,557	$ 7,184
Balance, shares at Dec. 31, 2014				13,962
Balance, redeemable noncontrolling interests at Dec. 31, 2014								$ 61,048
Net income	$ 286,459	283,138	282,361		282,361	0	777	3,321
Other comprehensive income (loss)	(133,535)	(133,479)	(133,479)		0	(133,479)	0	(56)
Comprehensive Income (Loss)	152,924	149,659	148,882				777	3,265
Issuance of common stock		3,609	3,609	$ 3,609	0	0	0	0
Issuance of common stock, shares				15
Repurchase of common stock		(22,670)	(22,670)	$ 0	(22,670)	0	0	0
Repurchase of common stock, shares				(27)
Restricted stock units expensed		14,968	14,968	$ 14,968	0	0	0	0
Restricted stock units expensed, shares				0
Adjustment of redeemable noncontrolling interests		1,715	1,715	$ 0	1,715	0	0	(1,715)
Adjustment of redeemable noncontrolling interests, shares				0
Purchase of noncontrolling interest		(1,447)	(1,447)	$ (1,447)	0	0	0	(8,224)
Purchase of noncontrolling interest, shares				0
Other		2,040	1,995	$ 1,964	31	0	45	(2,482)
Other, shares				0
Balance at Jun. 30, 2015		7,749,876	7,741,870	$ 3,327,489	2,843,303	1,571,078	8,006
Balance, shares at Jun. 30, 2015				13,950
Balance, redeemable noncontrolling interests at Jun. 30, 2015								51,892
Balance at Dec. 31, 2015	7,840,609	7,840,609	7,834,150	$ 3,342,357	3,137,285	1,354,508	6,459
Balance, shares at Dec. 31, 2015				13,959
Balance, redeemable noncontrolling interests at Dec. 31, 2015	62,958							62,958
Net income	244,319	239,957	239,167		239,167	0	790	4,362
Other comprehensive income (loss)	367,788	367,769	367,769		0	367,769	0	19
Comprehensive Income (Loss)	612,107	607,726	606,936				790	4,381
Issuance of common stock		4,101	4,101	$ 4,101	0	0	0	0
Issuance of common stock, shares				48
Repurchase of common stock		(15,206)	(15,206)	$ 0	(15,206)	0	0	0
Repurchase of common stock, shares				(16)
Restricted stock units expensed		13,473	13,473	$ 13,473	0	0	0	0
Restricted stock units expensed, shares				0
Adjustment of redeemable noncontrolling interests		(5,981)	(5,981)	$ 0	(5,981)	0	0	5,981
Adjustment of redeemable noncontrolling interests, shares				0
Purchase of noncontrolling interest		899	899	$ 899	0	0	0	(3,977)
Purchase of noncontrolling interest, shares				0
Other		(48)	(3)	$ 0	(3)	0	(45)	(3,142)
Other, shares				0
Balance at Jun. 30, 2016	8,445,573	$ 8,445,573	$ 8,438,369	$ 3,360,830	$ 3,355,262	$ 1,722,277	$ 7,204
Balance, shares at Jun. 30, 2016				13,991
Balance, redeemable noncontrolling interests at Jun. 30, 2016	$ 66,201							$ 66,201

Condensed Consolidated Statemen

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
OPERATING ACTIVITIES
Net income	$ 244,319	$ 286,459
Adjustments to reconcile net income to net cash provided (used) by operating activities	(174,105)	(48,424)
Net Cash Provided By Operating Activities	70,214	238,035
INVESTING ACTIVITIES
Proceeds from sales of fixed maturities and equity securities	226,492	99,908
Proceeds from maturities, calls and prepayments of fixed maturities	471,907	810,934
Cost of fixed maturities and equity securities purchased	(1,324,755)	(556,934)
Net change in short-term investments	(348,335)	(595,971)
Proceeds from sales of equity method investments	6,479	21,365
Cost of equity method investments	(1,126)	(19,424)
Change in restricted cash and cash equivalents	90,003	(9,748)
Additions to property and equipment	(34,634)	(38,942)
Acquisitions, net of cash acquired	5,762	0
Other	(605)	489
Net Cash Used By Investing Activities	(920,336)	(288,323)
FINANCING ACTIVITIES
Additions to senior long-term debt and other debt	533,235	41,230
Repayment of senior long-term debt and other debt	(228,836)	(43,044)
Premiums and fees related to early extinguishment of debt	(43,691)	0
Repurchases of common stock	(15,206)	(22,670)
Issuance of common stock	4,101	3,609
Purchase of noncontrolling interests	(3,078)	(12,474)
Distributions to noncontrolling interests	(3,187)	(2,490)
Other	(13,428)	(12,454)
Net Cash Provided (Used) By Financing Activities	229,910	(48,293)
Effect of foreign currency rate changes on cash and cash equivalents	(1,859)	(8,644)
Decrease in cash and cash equivalents	(622,071)	(107,225)
Cash and cash equivalents at beginning of period	2,630,009	1,960,169
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 2,007,938	$ 1,852,944

Summary Of Significant Accounti

Summary Of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies a) Basis of Presentation. Markel Corporation is a diverse financial holding company serving a variety of niche markets. Markel Corporation's principal business markets and underwrites specialty insurance products and programs. Through its wholly-owned subsidiary, Markel Ventures, Inc. (Markel Ventures), Markel Corporation also owns interests in various industrial and service businesses that operate outside of the specialty insurance marketplace. The consolidated balance sheet as of June 30, 2016 , the related consolidated statements of income and comprehensive income (loss) for the quarters and six months ended June 30, 2016 and 2015 , and the consolidated statements of changes in equity and cash flows for the six months ended June 30, 2016 and 2015 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, 2015 was derived from Markel Corporation's audited annual consolidated financial statements. The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and include the accounts of Markel Corporation and 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. 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. In addition to the policies set forth below, readers are urged to review the Company's 2015 Annual Report on Form 10-K for a more complete description of the Company's business and accounting policies. b) Variable Interest Entities. The Company determines whether it has relationships with entities defined as VIEs in accordance with Accounting Standards Codification (ASC) Topic 810, Consolidation . Under this guidance, a VIE is consolidated by the variable interest holder that is determined to be the primary beneficiary. An entity in which the Company holds a variable interest is a VIE if any of the following conditions exist: (a) the total equity investment at risk is not sufficient to permit the entity to finance its activities without additional subordinated financial support, (b) as a group, the holders of equity investment at risk lack either the direct or indirect ability through voting rights or similar rights to make decisions about an entity's activities that most significantly impact the entity’s economic performance or the obligation to absorb the expected losses or right to receive the expected residual returns, or (c) the voting rights of some investors are disproportionate to their obligation to absorb the expected losses of the entity, their rights to receive the expected residual returns of the entity, or both and substantially all of the entity's activities either involve or are conducted on behalf of an investor with disproportionately few voting rights. The primary beneficiary is defined as the variable interest holder that is determined to have the controlling financial interest as a result of having both (a) the power to direct the activities of a VIE that most significantly impact the economic performance of the VIE and (b) the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. The Company determines whether an entity is a VIE at the inception of our variable interest in the entity and upon the occurrence of certain reconsideration events. The Company continually reassesses whether it is the primary beneficiary of VIEs in which it holds a variable interest. c) Revenue Recognition. Investment Management and Performance Fees Investment management fee income is recognized over the period in which investment management services are provided and is calculated and billed monthly based on the net asset value of the accounts managed. Performance fee arrangements entitle the Company to participate, on a fixed-percentage basis, in any net income generated in excess of an agreed-upon threshold as established by the underlying investment management agreements. In general, net income is calculated at the end of each calendar year and performance fees are payable annually. Following the preferred method identified in the ASC Topic 605, Revenue Recognition , such performance fee income is recorded at the conclusion of the contractual performance period, when all contingencies are resolved.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	6 Months Ended
	Jun. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Effective January 1, 2016, the Company adopted Financial Accounting Standards Board (FASB) Accounting Standards Update (ASU) No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis , which changes the way reporting enterprises evaluate whether (a) they should consolidate limited partnerships and similar entities, (b) fees paid to a decision maker or service provider are variable interests in a VIE, and (c) variable interests in a VIE held by related parties of the reporting enterprise require the reporting enterprise to consolidate the VIE. It also eliminates the VIE consolidation model based on majority exposure to variability that applied to certain investment companies and similar entities. The ASU also significantly changes how to evaluate voting rights for entities that are not similar to limited partnerships when determining whether the entity is a VIE, which may affect entities for which the decision making rights are conveyed through a contractual arrangement. The adoption of this guidance did not result in any changes to our previous consolidation conclusions. Effective January 1, 2016, the Company adopted FASB ASU No. 2015-03, Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs . ASU No. 2015-03 requires that debt issuance costs related to a recognized debt liability be presented on the balance sheet as a direct deduction from the debt liability, similar to the presentation of debt discounts. The cost of issuing debt is no longer recorded as a separate asset on the balance sheet. The amortization of debt issuance costs continues to be included in interest expense. ASU No. 2015-03 was applied retrospectively to all periods presented. As a result, debt issuance costs totaling $2.2 million were reclassified from other assets to senior long-term debt and other debt as of December 31, 2015. The adoption of this ASU did not have an impact on the Company's results of operations or cash flows. Effective January 1, 2016, the Company adopted FASB ASU No. 2015-05, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer's Accounting for Fees Paid in a Cloud Computing Arrangement , which clarifies that software licenses contained in a cloud computing arrangement should be capitalized if the customer has the right to take possession of the software and the ability to run the software outside of the cloud computing arrangement. The adoption of this ASU did not have an impact on the Company's financial position, results of operations or cash flows. Effective January 1, 2016, the Company adopted FASB ASU No. 2015-16, Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments . ASU No. 2015-16 eliminates the requirement to retrospectively adjust the financial statements for measurement-period adjustments that occur in periods after a business combination is consummated. The adoption of this ASU did not have an impact on the Company's financial position, results of operations or cash flows and will be applied on a prospective basis, as applicable. During the second quarter of 2016, the Company early adopted FASB ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting , which changes several aspects of the accounting for share-based payment award transactions. Under the new guidance, all excess tax benefits or deficiencies associated with share-based payment award transactions are required to be recognized as an income tax benefit or expense in net income when the awards vest or are settled, with the corresponding cash flows recognized as an operating activity in the statement of cash flows. Excess tax benefits and deficiencies are no longer recognized in additional paid-in-capital. The new guidance also allows an employer to repurchase more of an employee's shares for tax witholding purposes without triggering liability accounting and to make a policy election to account for forfeitures as they occur, rather than estimating forfeitures upon issuance of the award. Upon adoption of ASU No. 2016-09, the Company elected to account for forfeitures as they occur, which had no impact on the consolidated financial statements. The provisions of ASU No. 2016-09 were adopted as of January 1, 2016 on a prospective basis and did not have a material impact on the Company's financial position, results of operations or cash flows. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) , which creates a new comprehensive revenue recognition standard that will serve as a single source of revenue guidance for all companies in all industries. The guidance applies to all companies that either enter into contracts with customers to transfer goods or services or enter into contracts for the transfer of nonfinancial assets, unless those contracts are within the scope of other standards, such as insurance contracts. ASU No. 2014-09's core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under the current guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606), Deferral of the Effective Date , which deferred the original effective date of ASU No. 2014-09 by one year. As a result, ASU No. 2014-09 becomes effective for the Company during the first quarter of 2018 and may be applied retrospectively or under a modified retrospective method where the cumulative effect is recognized at the date of initial application. Early application is permitted, but not before the first quarter of 2017. ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Consideration (Reporting Revenue Gross versus Net), ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing and ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients were issued in March, April and May 2016, respectively, as amendments to ASU No. 2014-09. These amendments will be evaluated and adopted in conjunction with ASU No. 2014-09. The Company is currently evaluating ASU No. 2014-09, and the related amendments, to determine the potential impact that adopting this standard will have on its consolidated financial statements. Adoption of this ASU is not expected to have a material impact on the Company's insurance operations, but may have a material impact on the Company's non-insurance operations. In May 2015, the FASB issued ASU No. 2015-09, Financial Services-Insurance (Topic 944): Disclosures about Short-Duration Contracts . The ASU requires significant new disclosures for insurers relating to short-duration insurance contract claims and the unpaid claims liability rollforward for long and short-duration contracts. The guidance requires annual tabular disclosure, on a disaggregated basis, of undiscounted incurred and paid claim and allocated claim adjustment expense development by accident year, on a net basis after reinsurance, for up to 10 years. Tables must also include the total incurred but not reported claims liabilities, plus expected development on reported claims, and claims frequency for each accident year. A description of estimation methodologies and any significant changes in methodologies and assumptions used to calculate the liability and frequency is also required. Based on the disaggregated claims information in the tables, disclosure of historical average annual percentage payout of incurred claims is also required. Interim period disclosures must include a tabular rollforward and related qualitative information for the liability for unpaid losses and loss adjustment expenses. Annual disclosures required by ASU No. 2015-09 become effective for the Company during 2016, with interim disclosures required beginning in the first quarter of 2017. The ASU must be applied retrospectively by providing comparative disclosures for each period presented. Early application is permitted. The adoption of this ASU will not have an impact on the Company's financial position, results of operations or cash flows, but will expand the nature and extent of its insurance contract disclosures, as described above. In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory . The ASU changes the measurement principle for inventory from the lower of cost or market to lower of cost and net realizable value and eliminates the requirement to consider replacement cost or net realizable value less an approximately normal profit margin when measuring inventory. ASU No. 2015-11 becomes effective for the Company during the first quarter of 2017 and will be applied prospectively. Adoption of this ASU is not expected to have a material impact on the Company's financial position, results of operations or cash flows. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments (Topic 825): Recognition and Measurement of Financial Assets and Financial Liabilities . The ASU significantly changes the income statement impact of equity investments and the recognition of changes in fair value of financial liabilities attributable to an entity's own credit risk when the fair value option is elected. The ASU requires equity instruments that do not result in consolidation and are not accounted for under the equity method to be measured at fair value and to recognize any changes in fair value in net income rather than other comprehensive income (loss). ASU No. 2016-01 becomes effective for the Company during the first quarter of 2018 and will be applied using a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. The provisions related to equity investments without a readily determinable fair value will be applied prospectively to equity investments as of the adoption date. Early adoption is permitted for certain provisions of the ASU. The Company is currently evaluating ASU No. 2016-01 to determine the potential impact that adopting this standard will have on the consolidated financial statements. Adoption of this ASU is not expected to have a material impact on the Company's financial position, cash flows, or total comprehensive income (loss), but will have a significant impact on the Company's results of operations as changes in fair value will be presented in net income rather than other comprehensive income (loss). In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) . The ASU requires lessees to put most leases on their balance sheets as a lease liability with a corresponding right-of-use asset, but continue to recognize the related leasing expense within net income. The guidance also eliminates the real estate-specific provisions for all entities. For lessors, the guidance modifies the classification criteria and the accounting for sales-type and direct financing leases. ASU No. 2016-02 becomes effective for the Company during the first quarter of 2019 and will be applied under a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. Early adoption is permitted. The Company is currently evaluating ASU No. 2016-02 to determine the potential impact that adopting this standard will have on the consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-07, Investments - Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to the Equity Method of Accounting. The ASU eliminates the requirement for an investor to retroactively apply the equity method when its increase in ownership interest or degree of influence in an investee triggers equity method accounting. ASU No. 2016-07 becomes effective for the Company during the first quarter of 2017 and will be applied prospectively. Early adoption is permitted. Adoption of this ASU is not expected to have an impact on the Company's financial position, results of operations or cash flows. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The ASU replaces the current incurred loss model used to measure impairment losses with an expected loss model for trade, reinsurance, and other receivables as well as financial instruments measured at amortized cost. For available-for-sale debt securities, 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 the beginning of the first reporting period in which the guidance is effective. The Company is currently evaluating ASU No. 2016-13 to determine the potential impact that adopting this standard will have on the consolidated financial statements.

Acquisitions

Acquisitions	6 Months Ended
	Jun. 30, 2016
Business Combinations [Abstract]
Acquisitions	Acquisitions In December 2015, the Company acquired 80% of the outstanding shares of CapTech Ventures, Inc. (CapTech), a privately held company headquartered in Richmond, Virginia. CapTech is a management and IT consulting firm, providing services and solutions to a wide array of customers. Total consideration for the CapTech acquisition was $60.6 million . As of December 31, 2015, the purchase price was preliminarily allocated to the acquired assets and liabilities based on the estimated fair values at the acquisition date. During the first quarter of 2016, the Company completed the process of determining the fair value of the assets and liabilities acquired with CapTech. There were no material adjustments to the provisional estimates recorded as of December 31, 2015. Results attributable to this acquisition are included with the Company's non-insurance operations, which are not included in a reportable segment.

Investments

Investments	6 Months Ended
	Jun. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Investments	Investments a) The following tables summarize the Company's available-for-sale investments. June 30, 2016 (dollars in thousands) Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Unrealized Other-Than- Temporary Impairment Losses Estimated Fair Value Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ 674,801 $ 25,489 $ (9 ) $ — $ 700,281 Obligations of states, municipalities and political subdivisions 4,193,114 370,264 (2,329 ) — 4,561,049 Foreign governments 1,349,640 233,884 (305 ) — 1,583,219 Commercial mortgage-backed securities 975,606 48,531 (533 ) — 1,023,604 Residential mortgage-backed securities 805,631 57,100 (529 ) (2,258 ) 859,944 Asset-backed securities 28,232 127 (17 ) — 28,342 Corporate bonds 1,563,313 82,823 (1,293 ) (1,653 ) 1,643,190 Total fixed maturities 9,590,337 818,218 (5,015 ) (3,911 ) 10,399,629 Equity securities: Insurance, banks and other financial institutions 835,144 769,505 (12,641 ) — 1,592,008 Industrial, consumer and all other 1,555,040 1,270,474 (21,953 ) — 2,803,561 Total equity securities 2,390,184 2,039,979 (34,594 ) — 4,395,569 Short-term investments 1,995,368 124 (1 ) — 1,995,491 Investments, available-for-sale $ 13,975,889 $ 2,858,321 $ (39,610 ) $ (3,911 ) $ 16,790,689 December 31, 2015 (dollars in thousands) Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Unrealized Other-Than- Temporary Impairment Losses Estimated Fair Value Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ 695,652 $ 9,836 $ (4,781 ) $ — $ 700,707 Obligations of states, municipalities and political subdivisions 3,817,136 204,302 (8,225 ) — 4,013,213 Foreign governments 1,302,329 115,809 (1,681 ) — 1,416,457 Commercial mortgage-backed securities 657,670 6,867 (4,999 ) — 659,538 Residential mortgage-backed securities 837,964 22,563 (4,022 ) (2,258 ) 854,247 Asset-backed securities 36,462 15 (406 ) — 36,071 Corporate bonds 1,690,945 41,123 (16,209 ) (1,624 ) 1,714,235 Total fixed maturities 9,038,158 400,515 (40,323 ) (3,882 ) 9,394,468 Equity securities: Insurance, banks and other financial institutions 651,002 690,271 (6,551 ) — 1,334,722 Industrial, consumer and all other 1,557,832 1,227,052 (45,131 ) — 2,739,753 Total equity securities 2,208,834 1,917,323 (51,682 ) — 4,074,475 Short-term investments 1,642,103 167 (9 ) — 1,642,261 Investments, available-for-sale $ 12,889,095 $ 2,318,005 $ (92,014 ) $ (3,882 ) $ 15,111,204 b) The following tables summarize gross unrealized investment losses by the length of time that securities have continuously been in an unrealized loss position. June 30, 2016 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ 7,537 $ (7 ) $ 8,529 $ (2 ) $ 16,066 $ (9 ) Obligations of states, municipalities and political subdivisions 2,789 (2 ) 47,301 (2,327 ) 50,090 (2,329 ) Foreign governments 42,255 (304 ) 5,026 (1 ) 47,281 (305 ) Commercial mortgage-backed securities 23,518 (142 ) 63,738 (391 ) 87,256 (533 ) Residential mortgage-backed securities 6,584 (2,304 ) 104,340 (483 ) 110,924 (2,787 ) Asset-backed securities — — 6,316 (17 ) 6,316 (17 ) Corporate bonds 37,222 (1,664 ) 104,194 (1,282 ) 141,416 (2,946 ) Total fixed maturities 119,905 (4,423 ) 339,444 (4,503 ) 459,349 (8,926 ) Equity securities: Insurance, banks and other financial institutions 77,737 (12,641 ) — — 77,737 (12,641 ) Industrial, consumer and all other 191,170 (19,887 ) 27,819 (2,066 ) 218,989 (21,953 ) Total equity securities 268,907 (32,528 ) 27,819 (2,066 ) 296,726 (34,594 ) Short-term investments 99,977 (1 ) — — 99,977 (1 ) Total $ 488,789 $ (36,952 ) $ 367,263 $ (6,569 ) $ 856,052 $ (43,521 ) At June 30, 2016 , the Company held 216 securities with a total estimated fair value of $856.1 million and gross unrealized losses of $43.5 million . Of these 216 securities, 126 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $367.3 million and gross unrealized losses of $6.6 million . Of these securities, 119 securities were fixed maturities and seven were equity securities. The Company does not intend to sell or believe it will be required to sell these fixed maturities before recovery of their amortized cost. The Company has the ability and intent to hold these equity securities for a period of time sufficient to allow for the anticipated recovery of their fair value. December 31, 2015 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ 427,003 $ (3,648 ) $ 92,552 $ (1,133 ) $ 519,555 $ (4,781 ) Obligations of states, municipalities and political subdivisions 169,362 (4,864 ) 70,101 (3,361 ) 239,463 (8,225 ) Foreign governments 51,328 (249 ) 40,345 (1,432 ) 91,673 (1,681 ) Commercial mortgage-backed securities 289,058 (3,600 ) 95,843 (1,399 ) 384,901 (4,999 ) Residential mortgage-backed securities 78,814 (2,858 ) 137,100 (3,422 ) 215,914 (6,280 ) Asset-backed securities 6,228 (54 ) 24,315 (352 ) 30,543 (406 ) Corporate bonds 470,694 (9,509 ) 343,737 (8,324 ) 814,431 (17,833 ) Total fixed maturities 1,492,487 (24,782 ) 803,993 (19,423 ) 2,296,480 (44,205 ) Equity securities: Insurance, banks and other financial institutions 63,873 (6,384 ) 6,247 (167 ) 70,120 (6,551 ) Industrial, consumer and all other 344,857 (44,879 ) 2,907 (252 ) 347,764 (45,131 ) Total equity securities 408,730 (51,263 ) 9,154 (419 ) 417,884 (51,682 ) Short-term investments 129,473 (9 ) — — 129,473 (9 ) Total $ 2,030,690 $ (76,054 ) $ 813,147 $ (19,842 ) $ 2,843,837 $ (95,896 ) At December 31, 2015 , the Company held 659 securities with a total estimated fair value of $2.8 billion and gross unrealized losses of $95.9 million . Of these 659 securities, 271 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $813.1 million and gross unrealized losses of $19.8 million . Of these securities, 264 securities were fixed maturities and seven were equity securities. 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 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 equity securities, the ability and intent to hold the security for a period of time sufficient to allow for anticipated recovery is considered. 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 equity securities, a decline in fair value that is considered to be other-than-temporary 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. 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 (loss). The discount rate used to calculate the estimated present value of the cash flows expected to be collected is the effective interest rate implicit for the security at the date of purchase. When assessing whether it intends to sell a fixed maturity or if it is likely to be required to sell a fixed maturity before recovery of its amortized cost, the Company evaluates facts and circumstances including decisions to reposition the investment portfolio, potential sales of investments to meet cash flow needs and, ultimately, current market prices. c) The amortized cost and estimated fair value of fixed maturities at June 30, 2016 are shown below by contractual maturity. (dollars in thousands) Amortized Cost Estimated Fair Value Due in one year or less $ 720,305 $ 726,444 Due after one year through five years 1,386,900 1,441,314 Due after five years through ten years 1,654,425 1,802,966 Due after ten years 4,019,238 4,517,015 7,780,868 8,487,739 Commercial mortgage-backed securities 975,606 1,023,604 Residential mortgage-backed securities 805,631 859,944 Asset-backed securities 28,232 28,342 Total fixed maturities $ 9,590,337 $ 10,399,629 d) The following table presents the components of net investment income. Quarter Ended June 30, Six Months Ended June 30, (dollars in thousands) 2016 2015 2016 2015 Interest: Municipal bonds (tax-exempt) $ 22,563 $ 24,293 $ 44,485 $ 50,145 Municipal bonds (taxable) 16,222 14,150 32,110 28,250 Other taxable bonds 36,959 34,013 72,278 69,151 Short-term investments, including overnight deposits 2,654 1,116 4,945 2,367 Dividends on equity securities 16,758 18,633 34,410 37,657 Income from equity method investments 3,921 1,712 3,668 3,056 Other 190 479 2,674 540 99,267 94,396 194,570 191,166 Investment expenses (4,271 ) (3,810 ) (8,280 ) (7,705 ) Net investment income $ 94,996 $ 90,586 $ 186,290 $ 183,461 e) The following table presents net realized investment gains and the change in net unrealized gains on investments. Quarter Ended June 30, Six Months Ended June 30, (dollars in thousands) 2016 2015 2016 2015 Realized gains: Sales of fixed maturities $ 699 $ 770 $ 967 $ 2,338 Sales of equity securities 17,798 7,000 45,526 22,956 Other 353 1,739 773 2,413 Total realized gains 18,850 9,509 47,266 27,707 Realized losses: Sales of fixed maturities (142 ) (97 ) (555 ) (221 ) Sales of equity securities (1,780 ) (113 ) (2,498 ) (272 ) Other-than-temporary impairments (3,675 ) — (12,080 ) (5,092 ) Other (718 ) (16 ) (2,996 ) (227 ) Total realized losses (6,315 ) (226 ) (18,129 ) (5,812 ) Gains (losses) on securities measured at fair value through net income 4,706 (3,178 ) 9,283 (10,219 ) Net realized investment gains $ 17,241 $ 6,105 $ 38,420 $ 11,676 Change in net unrealized gains on investments included in other comprehensive income (loss): Fixed maturities $ 213,026 $ (286,551 ) $ 452,982 $ (180,213 ) Equity securities 42,786 (64,792 ) 139,744 (6,447 ) Short-term investments 32 11 (35 ) (9 ) Net increase (decrease) $ 255,844 $ (351,332 ) $ 592,691 $ (186,669 ) For the quarter ended June 30, 2016, other-than-temporary impairment losses recognized in net income and included in net realized investment gains totaled $3.7 million and were attributable to 12 equity securities. The write downs for the quarter included $3.0 million related to equities in industrial, consumer, or other types of businesses and $0.6 million related to equities in insurance, banks, and other financial institutions. For the six months ended June 30, 2016 , other-than-temporary impairment losses recognized in net income and included in net realized investment gains totaled $12.1 million and were attributable to 21 equity securities. The write downs for the six-month period included $10.8 million related to equities in industrial, consumer, or other types of businesses and $1.3 million related to equities in insurance, banks, and other financial institutions. For the six months ended June 30, 2015 , other-than-temporary impairment losses recognized in net income and included in net realized investment gains totaled $5.1 million and were attributable to 10 equity securities. The write downs for the six-month period included $4.5 million related to equities in industrial, consumer, or other types of businesses and $0.6 million related to equities in insurance, banks, and other financial institutions.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements FASB ASC 820-10, 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 FASB 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. Investments available-for-sale. Investments available-for-sale are recorded at fair value on a recurring basis and include fixed maturities, equity securities 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 investments available-for-sale is determined by the Company after considering various sources of information, including information provided by a third party pricing service. The pricing service provides prices for substantially all of the Company's fixed 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 and obligations of U.S. government agencies, 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 insurance-linked securities funds (the ILS Funds), as further described in note 12 , which are not traded on an active exchange and are valued using unobservable inputs. Fair value for investments available-for-sale 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 ILS Funds, these investments are classified as Level 3 within the fair value hierarchy. Changes in fair value of the ILS Funds are included in net realized gains (losses) in net income. 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 ILS 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 ILS Funds in exchange for notes receivable, rather than cash, which is excluded from NAV. The Company's investments in the ILS Funds are redeemable annually as of January 1 st of each calendar year. 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, which includes the price of a comparable security and an insurance-linked security index. 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 and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy. June 30, 2016 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments available-for-sale: Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ — $ 700,281 $ — $ 700,281 Obligations of states, municipalities and political subdivisions — 4,561,049 — 4,561,049 Foreign governments — 1,583,219 — 1,583,219 Commercial mortgage-backed securities — 1,023,604 — 1,023,604 Residential mortgage-backed securities — 859,944 — 859,944 Asset-backed securities — 28,342 — 28,342 Corporate bonds — 1,643,190 — 1,643,190 Total fixed maturities — 10,399,629 — 10,399,629 Equity securities: Insurance, banks and other financial institutions 1,408,485 — 183,523 1,592,008 Industrial, consumer and all other 2,803,561 — — 2,803,561 Total equity securities 4,212,046 — 183,523 4,395,569 Short-term investments 1,877,297 118,194 — 1,995,491 Total investments available-for-sale $ 6,089,343 $ 10,517,823 $ 183,523 $ 16,790,689 December 31, 2015 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments available-for-sale: Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ — $ 700,707 $ — $ 700,707 Obligations of states, municipalities and political subdivisions — 4,013,213 — 4,013,213 Foreign governments — 1,416,457 — 1,416,457 Commercial mortgage-backed securities — 659,538 — 659,538 Residential mortgage-backed securities — 854,247 — 854,247 Asset-backed securities — 36,071 — 36,071 Corporate bonds — 1,714,235 — 1,714,235 Total fixed maturities — 9,394,468 — 9,394,468 Equity securities: Insurance, banks and other financial institutions 1,334,722 — — 1,334,722 Industrial, consumer and all other 2,739,753 — — 2,739,753 Total equity securities 4,074,475 — — 4,074,475 Short-term investments 1,529,924 112,337 — 1,642,261 Total investments available-for-sale $ 5,604,399 $ 9,506,805 $ — $ 15,111,204 The following table summarizes changes in Level 3 investments measured at fair value on a recurring basis. Quarter Ended June 30, Six Months Ended June 30, (dollars in thousands) 2016 2015 2016 2015 Equity securities, beginning of period $ 176,942 $ — $ — $ — Purchases 25,000 — 195,250 — Sales (25,000 ) — (25,000 ) — Total gains included in: Net income 6,581 — 13,273 — Other comprehensive income (loss) — — — — Transfers into Level 3 — — — — Transfers out of Level 3 — — — — Equity securities, end of period $ 183,523 $ — $ 183,523 $ — Net unrealized gains included in net income relating to assets held at June 30, 2016 and 2015 (1) $ 6,581 $ — $ 13,273 $ — (1) Included in net realized investment gains in the consolidated statements of income and comprehensive income (loss). There were no transfers into or out of Level 1 and Level 2 during the quarter and six months ended June 30, 2016 and 2015 . The Company did not have any assets or liabilities measured at fair value on a non-recurring basis during the six months ended June 30, 2016 and 2015 .

Segment Reporting Disclosures

Segment Reporting Disclosures	6 Months Ended
	Jun. 30, 2016
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Segment Reporting Disclosures	Segment Reporting Disclosures The Company monitors and reports its ongoing underwriting operations in the following three segments: U.S. Insurance, International Insurance and Reinsurance. In determining how to aggregate and monitor its underwriting results, the Company considers many factors, including the geographic location and regulatory environment of the insurance entity underwriting the risk, the nature of the insurance product sold, the type of account written and the type of customer served. The U.S. Insurance segment includes all direct business and facultative placements written by the Company's insurance subsidiaries domiciled in the United States. The International Insurance segment includes all direct business and facultative placements written by the Company's insurance subsidiaries domiciled outside of the United States, including the Company's syndicate at Lloyd's of London. The Reinsurance segment includes all treaty reinsurance written across the Company. Results for lines of business discontinued prior to, or in conjunction with, acquisitions, including the results attributable to the run-off of life and annuity reinsurance business, are reported in the Other Insurance (Discontinued Lines) segment. All investing activities related to the Company's insurance operations are included in the Investing segment. The Company's non-insurance operations include the Company's Markel Ventures operations, which primarily consist of controlling interests in various industrial and service businesses. The Company's non-insurance operations also include the results of the Company's legal and professional consulting services, and, effective December 8, 2015, the results of the Company's investment management services attributable to Markel CATCo Investment Management Ltd. For purposes of segment reporting, the Company's non-insurance operations are not considered to be a reportable segment. Segment profit for the Investing segment is measured by net investment income and net realized investment gains or losses. Segment profit or loss for each of the Company's underwriting segments is measured by underwriting profit or loss. The property and casualty insurance industry commonly defines underwriting profit or loss as earned premiums net of losses and loss adjustment expenses and underwriting, acquisition and insurance expenses. Underwriting profit or loss 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 or loss for the Company's underwriting segments also includes other revenues and other expenses, primarily related to the run-off of managing general agent operations that were discontinued in conjunction with acquisitions. Other revenues and other expenses in the Other Insurance (Discontinued Lines) segment are comprised of the results attributable to the run-off of life and annuity reinsurance business. For management reporting purposes, the Company allocates assets to its underwriting, investing and non-insurance operations. Underwriting assets are all assets not specifically allocated to the Investing segment or to the Company's non-insurance operations. Underwriting and investing assets are not allocated to the U.S. Insurance, International Insurance, Reinsurance or Other Insurance (Discontinued Lines) segments since the Company does not manage its assets by underwriting segment. The Company does not allocate capital expenditures for long-lived assets to any of its underwriting segments for management reporting purposes. a) The following tables summarize the Company's segment disclosures. Quarter Ended June 30, 2016 (dollars in thousands) U.S. Insurance International Insurance Reinsurance Other Insurance (Discontinued Lines) Investing Consolidated Gross premium volume $ 689,468 $ 318,581 $ 269,604 $ (4 ) $ — $ 1,277,649 Net written premiums 579,233 244,636 226,681 (4 ) — 1,050,546 Earned premiums 533,328 203,052 214,514 (35 ) — 950,859 Losses and loss adjustment expenses: Current accident year (352,092 ) (146,453 ) (152,693 ) — — (651,238 ) Prior accident years 66,332 39,002 34,644 (296 ) — 139,682 Underwriting, acquisition and insurance expenses (212,915 ) (96,562 ) (66,143 ) 40 — (375,580 ) Underwriting profit (loss) 34,653 (961 ) 30,322 (291 ) — 63,723 Net investment income — — — — 94,996 94,996 Net realized investment gains — — — — 17,241 17,241 Other revenues (insurance) 958 609 — 446 — 2,013 Other expenses (insurance) (684 ) (2,137 ) — (7,199 ) — (10,020 ) Segment profit (loss) $ 34,927 $ (2,489 ) $ 30,322 $ (7,044 ) $ 112,237 $ 167,953 Other revenues (non-insurance) 310,828 Other expenses (non-insurance) (267,889 ) Amortization of intangible assets (17,204 ) Interest expense (33,697 ) Loss on early extinguishment of debt (44,100 ) Income before income taxes $ 115,891 U.S. GAAP combined ratio (1) 94 % 100 % 86 % NM (2) 93 % Quarter Ended June 30, 2015 (dollars in thousands) U.S. Insurance International Insurance Reinsurance Other Insurance (Discontinued Lines) Investing Consolidated Gross premium volume $ 668,853 $ 338,159 $ 258,745 $ 29 $ — $ 1,265,786 Net written premiums 554,638 264,129 215,520 57 — 1,034,344 Earned premiums 520,446 223,941 213,140 30 — 957,557 Losses and loss adjustment expenses: Current accident year (341,335 ) (168,896 ) (154,623 ) — — (664,854 ) Prior accident years 68,620 43,373 15,118 1,549 — 128,660 Underwriting, acquisition and insurance expenses (211,856 ) (94,617 ) (73,170 ) (9 ) — (379,652 ) Underwriting profit 35,875 3,801 465 1,570 — 41,711 Net investment income — — — — 90,586 90,586 Net realized investment gains — — — — 6,105 6,105 Other revenues (insurance) 2,203 915 469 350 — 3,937 Other expenses (insurance) (1,284 ) (1,318 ) — (3,348 ) — (5,950 ) Segment profit (loss) $ 36,794 $ 3,398 $ 934 $ (1,428 ) $ 96,691 $ 136,389 Other revenues (non-insurance) 246,420 Other expenses (non-insurance) (236,286 ) Amortization of intangible assets (16,949 ) Interest expense (29,288 ) Income before income taxes $ 100,286 U.S. GAAP combined ratio (1) 93 % 98 % 100 % NM (2) 96 % (1) 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. (2) NM – Ratio is not meaningful. Six Months Ended June 30, 2016 (dollars in thousands) U.S. Insurance International Insurance Reinsurance Other Insurance (Discontinued Lines) Investing Consolidated Gross premium volume $ 1,337,258 $ 609,985 $ 723,090 $ (21 ) $ — $ 2,670,312 Net written premiums 1,131,978 471,035 629,407 86 — 2,232,506 Earned premiums 1,065,796 418,397 424,133 219 — 1,908,545 Losses and loss adjustment expenses: Current accident year (668,425 ) (291,929 ) (283,169 ) — — (1,243,523 ) Prior accident years 104,986 68,654 71,005 13,358 — 258,003 Underwriting, acquisition and insurance expenses (410,378 ) (185,168 ) (144,648 ) (74 ) — (740,268 ) Underwriting profit 91,979 9,954 67,321 13,503 — 182,757 Net investment income — — — — 186,290 186,290 Net realized investment gains — — — — 38,420 38,420 Other revenues (insurance) 2,377 4,730 — 941 — 8,048 Other expenses (insurance) (1,408 ) (3,691 ) — (15,200 ) — (20,299 ) Segment profit (loss) $ 92,948 $ 10,993 $ 67,321 $ (756 ) $ 224,710 $ 395,216 Other revenues (non-insurance) 610,816 Other expenses (non-insurance) (532,703 ) Amortization of intangible assets (34,464 ) Interest expense (64,538 ) Loss on early extinguishment of debt (44,100 ) Income before income taxes $ 330,227 U.S. GAAP combined ratio (1) 91 % 98 % 84 % NM (2) 90 % Six Months Ended June 30, 2015 (dollars in thousands) U.S. Insurance International Insurance Reinsurance Other Insurance (Discontinued Lines) Investing Consolidated Gross premium volume $ 1,254,218 $ 627,386 $ 636,582 $ 73 $ — $ 2,518,259 Net written premiums 1,050,807 486,837 531,732 398 — 2,069,774 Earned premiums 1,035,000 429,902 435,894 411 — 1,901,207 Losses and loss adjustment expenses: Current accident year (658,092 ) (317,740 ) (303,363 ) — — (1,279,195 ) Prior accident years 136,201 120,023 41,505 (1,723 ) — 296,006 Underwriting, acquisition and insurance expenses (397,116 ) (173,411 ) (149,723 ) (87 ) — (720,337 ) Underwriting profit (loss) 115,993 58,774 24,313 (1,399 ) — 197,681 Net investment income — — — — 183,461 183,461 Net realized investment gains — — — — 11,676 11,676 Other revenues (insurance) 3,605 6,302 892 327 — 11,126 Other expenses (insurance) (2,189 ) (2,722 ) — (10,697 ) — (15,608 ) Segment profit (loss) $ 117,409 $ 62,354 $ 25,205 $ (11,769 ) $ 195,137 $ 388,336 Other revenues (non-insurance) 499,289 Other expenses (non-insurance) (457,629 ) Amortization of intangible assets (31,589 ) Interest expense (58,600 ) Income before income taxes $ 339,807 U.S. GAAP combined ratio (1) 89 % 86 % 94 % NM (2) 90 % (1) 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. (2) NM – Ratio is not meaningful. b) The following table reconciles segment assets to the Company's consolidated balance sheets. (dollars in thousands) June 30, 2016 December 31, 2015 Segment assets: Investing $ 18,976,263 $ 18,056,947 Underwriting 5,822,696 5,385,126 Total segment assets 24,798,959 23,442,073 Non-insurance operations 1,536,669 1,497,042 Total assets $ 26,335,628 $ 24,939,115

Senior Long-Term Debt

Senior Long-Term Debt	6 Months Ended
	Jun. 30, 2016
Debt Disclosure [Abstract]
Senior Long-Term Debt	Senior Long-Term Debt On April 5, 2016, the Company issued $400 million of 5.0% unsecured senior notes due April 5, 2046. Net proceeds to the Company were $392.3 million . In April 2016, the Company used a portion of these proceeds to purchase $70.2 million of principal on its 7.35% Senior Notes due 2034 and $108.8 million of principal on its 7.125% Senior Notes due 2019 through a tender offer at a total purchase price of $95.0 million and $126.4 million , respectively. The Company also expects to use the proceeds from the April 2016 issuance to retire its 7.20% unsecured senior notes, when they come due April 14, 2017 ( $90.6 million aggregate principal amount of those notes was outstanding at June 30, 2016 ), and the remainder for general corporate purposes. On May 5, 2016, the Company issued an additional $100 million of 5.0% unsecured senior notes due April 5, 2046. Net proceeds to the Company were $100.8 million . The Company expects to use the proceeds for general corporate purposes. In connection with the tender offer and purchase, we recognized a loss on early extinguishment of debt of $44.1 million during the quarter and six months ended June 30, 2016.

Other Revenues And Other Expens

Other Revenues And Other Expenses	6 Months Ended
	Jun. 30, 2016
Other Income and Expenses [Abstract]
Other Revenues And Other Expenses	Other Revenues and Other Expenses The following tables summarize the components of other revenues and other expenses. Quarter Ended June 30, 2016 2015 (dollars in thousands) Other Revenues Other Expenses Other Revenues Other Expenses Insurance: Managing general agent operations $ 1,567 $ 2,821 $ 3,118 $ 2,602 Life and annuity 446 7,199 350 3,348 Other — — 469 — 2,013 10,020 3,937 5,950 Non-Insurance: Markel Ventures: Manufacturing 193,152 159,227 174,141 168,580 Markel Ventures: Non-Manufacturing 104,602 91,685 65,412 63,013 Investment management 7,350 10,836 — — Other 5,724 6,141 6,867 4,693 310,828 267,889 246,420 236,286 Total $ 312,841 $ 277,909 $ 250,357 $ 242,236 Six Months Ended June 30, 2016 2015 (dollars in thousands) Other Revenues Other Expenses Other Revenues Other Expenses Insurance: Managing general agent operations $ 7,107 $ 5,099 $ 8,988 $ 4,911 Life and annuity 941 15,200 327 10,697 Other — — 1,811 — 8,048 20,299 11,126 15,608 Non-Insurance: Markel Ventures: Manufacturing 385,843 319,593 351,903 320,380 Markel Ventures: Non-Manufacturing 198,430 180,118 133,093 126,843 Investment management 14,523 20,766 — — Other 12,020 12,226 14,293 10,406 610,816 532,703 499,289 457,629 Total $ 618,864 $ 553,002 $ 510,415 $ 473,237 The Company's Markel Ventures operations primarily consist of controlling interests in various industrial and service businesses and are viewed by management as separate and distinct from the Company's insurance operations. While each of the companies is operated independently from one another, management aggregates financial results into two industry groups: manufacturing and non-manufacturing.

Reinsurance

Reinsurance	6 Months Ended
	Jun. 30, 2016
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance The following tables summarize the effect of reinsurance and retrocessional reinsurance on premiums written and earned. Quarter Ended June 30, 2016 2015 (dollars in thousands) Written Earned Written Earned Direct $ 957,244 $ 865,943 $ 951,885 $ 875,376 Assumed 320,405 295,868 313,901 304,324 Ceded (227,103 ) (210,952 ) (231,442 ) (222,143 ) Net premiums $ 1,050,546 $ 950,859 $ 1,034,344 $ 957,557 Six Months Ended June 30, 2016 2015 (dollars in thousands) Written Earned Written Earned Direct $ 1,836,332 $ 1,733,387 $ 1,753,465 $ 1,719,946 Assumed 833,980 585,931 764,794 617,159 Ceded (437,806 ) (410,773 ) (448,485 ) (435,898 ) Net premiums $ 2,232,506 $ 1,908,545 $ 2,069,774 $ 1,901,207 The percentage of ceded earned premiums to gross earned premiums was 18% and 19% , respectively, for the quarters and six months ended June 30, 2016 and 2015 . The percentage of assumed earned premiums to net earned premiums was 31% and 32% , respectively, for the quarters and six months ended June 30, 2016 and 2015 . Incurred losses and loss adjustment expenses were net of reinsurance recoverables (ceded incurred losses and loss adjustment expenses) of $75.5 million and $143.3 million , respectively, for the quarters ended June 30, 2016 and 2015 and $206.1 million and $232.1 million , respectively, for the six months ended June 30, 2016 and 2015 .

Life And Annuity Benefits

Life And Annuity Benefits	6 Months Ended
	Jun. 30, 2016
Liability for Future Policy Benefits [Abstract]
Life And Annuity Benefits	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 six months ended June 30, 2016, 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 $47.9 million and decreasing the change in net unrealized holding gains included in other comprehensive income by a corresponding amount. As of June 30, 2016, the cumulative adjustment to life and annuity benefits attributable to unrealized gains on the underlying investment portfolio totaled $47.9 million .

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate was 26% and 16% for the six months ended June 30, 2016 and 2015 , respectively. For the six months ended June 30, 2016 , the effective tax rate differs from the U.S. statutory tax rate of 35% primarily as a result of tax-exempt investment income. For the six months ended June 30, 2015 , the effective tax rate differs from the U.S. statutory tax rate of 35% primarily as a result of foreign tax credits for foreign taxes paid and tax-exempt investment income. The Company's recognition of foreign tax credits in 2015 had a favorable impact on its effective tax rate for the six months ended June 30, 2015 of 12% . The increase in the effective tax rate in 2016 compared to 2015 was primarily due to the 2015 impact of foreign tax credits described above, partially offset by an increase in estimated annual earnings attributable to foreign operations that are taxed at a lower rate in 2016 compared to 2015. During the first quarter of 2016, the Internal Revenue Service completed its examination of the Company’s 2012 federal income tax return. There were no adjustments to our income tax liabilities as a result of this examination.

Variable Interest Entities

Variable Interest Entities	6 Months Ended
	Jun. 30, 2016
Variable Interest Entities [Abstract]
Variable Interest Entities	Variable Interest Entities In December 2015, the Company formed Markel CATCo Investment Management Ltd. (MCIM), a wholly-owned consolidated subsidiary. MCIM is an insurance-linked securities investment fund manager and insurance manager headquartered in Bermuda. Results attributable to MCIM are included with the Company's non-insurance operations, which are not included in a reportable segment. In December 2015, the Company also formed a mutual fund company and reinsurance company, both of which were organized under Bermuda law and are managed by MCIM. The mutual fund company issues multiple classes of nonvoting, redeemable preference shares to investors through its funds (the Funds) and the Funds are primarily invested in nonvoting shares of the reinsurance company. The underwriting results of the reinsurance company are attributed to the Funds through the issuance of nonvoting preference shares. The Funds and the reinsurance company 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 Funds or the reinsurance company, 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. The Company is the sole investor in one of the Funds, the Markel Diversified Fund, and consolidates that fund as its primary beneficiary. The Company also holds an investment in another one of the Funds ( $25.2 million as of June 30, 2016) but does not have the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE, and therefore does not consolidate that Fund. As of June 30, 2016 , total assets of the Markel Diversified Fund were $161.8 million and total liabilities were $63.9 million . The assets of the Markel Diversified Fund are available for use only by the Markel Diversified Fund, and are not available for use by the Company. Total assets of the Markel Diversified Fund include an investment in one of the unconsolidated Funds totaling $158.3 million , which represents 6% of the outstanding preference shares of that fund. This investment is included in equity securities (available-for-sale) on the Company’s consolidated balance sheet. Total liabilities of the Markel Diversified Fund include a $62.5 million note payable delivered as part of the consideration provided for its investment. This note payable is included in senior long-term debt and other debt on the Company’s consolidated balance sheet. Other than the note payable, any liabilities held by the Markel Diversified Fund have no recourse to the Company’s general credit. The Company’s exposure to risk from the unconsolidated Funds and reinsurance company is generally limited to its investment and any earned but uncollected fees. The Company has not issued any investment performance guarantees to these VIEs or their investors. As of June 30, 2016 , total investment and insurance assets under management of MCIM for unconsolidated VIEs were $3.4 billion .

Net Income Per Share

Net Income Per Share	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Net Income Per Share	Net Income 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 June 30, Six Months Ended June 30, (in thousands, except per share amounts) 2016 2015 2016 2015 Net income to shareholders $ 78,797 $ 91,369 $ 239,167 $ 282,361 Adjustment of redeemable noncontrolling interests (2,529 ) 3,062 (5,981 ) 1,715 Adjusted net income to shareholders $ 76,268 $ 94,431 $ 233,186 $ 284,076 Basic common shares outstanding 14,012 13,975 14,003 13,973 Dilutive potential common shares from conversion of options 4 9 5 10 Dilutive potential common shares from conversion of restricted stock 72 68 79 74 Diluted shares outstanding 14,088 14,052 14,087 14,057 Basic net income per share $ 5.44 $ 6.76 $ 16.65 $ 20.33 Diluted net income per share $ 5.41 $ 6.72 $ 16.55 $ 20.21

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2016
Other Comprehensive Income (Loss), Tax [Abstract]
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Other comprehensive income (loss) includes net holding gains (losses) 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 (loss) 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 by component, net of taxes and noncontrolling interests, for the six months ended June 30, 2016 and 2015 . (dollars in thousands) Unrealized Holding Gains on Available-for-Sale Securities Foreign Currency Net Actuarial Pension Loss Total December 31, 2014 $ 1,793,254 $ (43,491 ) $ (45,206 ) $ 1,704,557 Other comprehensive loss before reclassifications (109,001 ) (11,373 ) — (120,374 ) Amounts reclassified from accumulated other comprehensive income (14,037 ) — 932 (13,105 ) Total other comprehensive income (loss) (123,038 ) (11,373 ) 932 (133,479 ) June 30, 2015 $ 1,670,216 $ (54,864 ) $ (44,274 ) $ 1,571,078 December 31, 2015 $ 1,472,762 $ (72,696 ) $ (45,558 ) $ 1,354,508 Other comprehensive income before reclassifications 388,273 2,189 — 390,462 Amounts reclassified from accumulated other comprehensive income (23,550 ) — 857 (22,693 ) Total other comprehensive income 364,723 2,189 857 367,769 June 30, 2016 $ 1,837,485 $ (70,507 ) $ (44,701 ) $ 1,722,277 The following table summarizes the tax expense (benefit) associated with each component of other comprehensive income (loss). Quarter Ended June 30, Six Months Ended June 30, (dollars in thousands) 2016 2015 2016 2015 Change in net unrealized gains on investments: Net holding gains (losses) arising during the period $ 71,381 $ (113,579 ) $ 187,880 $ (57,997 ) Change in unrealized other-than-temporary impairment losses on fixed maturities arising during the period 9 (3 ) (6 ) 38 Reclassification adjustments for net gains included in net income (2,333 ) (2,576 ) (7,810 ) (5,672 ) Change in net unrealized gains on investments 69,057 (116,158 ) 180,064 (63,631 ) Change in foreign currency translation adjustments (1,618 ) 1,872 (1,695 ) 833 Change in net actuarial pension loss 86 117 188 233 Total $ 67,525 $ (114,169 ) $ 178,557 $ (62,565 ) The following table presents the details of amounts reclassified from accumulated other comprehensive income into income, by component. Quarter Ended June 30, Six Months Ended June 30, (dollars in thousands) 2016 2015 2016 2015 Unrealized holding gains on available-for-sale securities: Other-than-temporary impairment losses $ (3,675 ) $ — $ (12,080 ) $ (5,092 ) Net realized investment gains, excluding other-than-temporary impairment losses 16,575 7,560 43,440 24,801 Total before taxes 12,900 7,560 31,360 19,709 Income taxes (2,333 ) (2,576 ) (7,810 ) (5,672 ) Reclassification of unrealized holding gains, net of taxes $ 10,567 $ 4,984 $ 23,550 $ 14,037 Net actuarial pension loss: Underwriting, acquisition and insurance expenses $ (480 ) $ (586 ) $ (1,045 ) $ (1,165 ) Income taxes 86 117 188 233 Reclassification of net actuarial pension loss, net of taxes $ (394 ) $ (469 ) $ (857 ) $ (932 )

Contingencies

Contingencies	6 Months Ended
	Jun. 30, 2016
Loss Contingency [Abstract]
Contingencies	Contingencies Contingencies arise in the normal course of the Company's operations and are not expected to have a material impact on the Company's financial condition or results of operations.

Summary Of Significant Accoun22

Summary Of Significant Accounting Policies (Policy)	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation. Markel Corporation is a diverse financial holding company serving a variety of niche markets. Markel Corporation's principal business markets and underwrites specialty insurance products and programs. Through its wholly-owned subsidiary, Markel Ventures, Inc. (Markel Ventures), Markel Corporation also owns interests in various industrial and service businesses that operate outside of the specialty insurance marketplace. The consolidated balance sheet as of June 30, 2016 , the related consolidated statements of income and comprehensive income (loss) for the quarters and six months ended June 30, 2016 and 2015 , and the consolidated statements of changes in equity and cash flows for the six months ended June 30, 2016 and 2015 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, 2015 was derived from Markel Corporation's audited annual consolidated financial statements. The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and include the accounts of Markel Corporation and 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. 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. In addition to the policies set forth below, readers are urged to review the Company's 2015 Annual Report on Form 10-K for a more complete description of the Company's business and accounting policies.
Variable Interest Entities	Variable Interest Entities. The Company determines whether it has relationships with entities defined as VIEs in accordance with Accounting Standards Codification (ASC) Topic 810, Consolidation . Under this guidance, a VIE is consolidated by the variable interest holder that is determined to be the primary beneficiary. An entity in which the Company holds a variable interest is a VIE if any of the following conditions exist: (a) the total equity investment at risk is not sufficient to permit the entity to finance its activities without additional subordinated financial support, (b) as a group, the holders of equity investment at risk lack either the direct or indirect ability through voting rights or similar rights to make decisions about an entity's activities that most significantly impact the entity’s economic performance or the obligation to absorb the expected losses or right to receive the expected residual returns, or (c) the voting rights of some investors are disproportionate to their obligation to absorb the expected losses of the entity, their rights to receive the expected residual returns of the entity, or both and substantially all of the entity's activities either involve or are conducted on behalf of an investor with disproportionately few voting rights. The primary beneficiary is defined as the variable interest holder that is determined to have the controlling financial interest as a result of having both (a) the power to direct the activities of a VIE that most significantly impact the economic performance of the VIE and (b) the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. The Company determines whether an entity is a VIE at the inception of our variable interest in the entity and upon the occurrence of certain reconsideration events. The Company continually reassesses whether it is the primary beneficiary of VIEs in which it holds a variable interest.
Revenue Recognition	Revenue Recognition. Investment Management and Performance Fees Investment management fee income is recognized over the period in which investment management services are provided and is calculated and billed monthly based on the net asset value of the accounts managed. Performance fee arrangements entitle the Company to participate, on a fixed-percentage basis, in any net income generated in excess of an agreed-upon threshold as established by the underlying investment management agreements. In general, net income is calculated at the end of each calendar year and performance fees are payable annually. Following the preferred method identified in the ASC Topic 605, Revenue Recognition , such performance fee income is recorded at the conclusion of the contractual performance period, when all contingencies are resolved.

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Available-For-Sale Investments	The following tables summarize the Company's available-for-sale investments. June 30, 2016 (dollars in thousands) Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Unrealized Other-Than- Temporary Impairment Losses Estimated Fair Value Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ 674,801 $ 25,489 $ (9 ) $ — $ 700,281 Obligations of states, municipalities and political subdivisions 4,193,114 370,264 (2,329 ) — 4,561,049 Foreign governments 1,349,640 233,884 (305 ) — 1,583,219 Commercial mortgage-backed securities 975,606 48,531 (533 ) — 1,023,604 Residential mortgage-backed securities 805,631 57,100 (529 ) (2,258 ) 859,944 Asset-backed securities 28,232 127 (17 ) — 28,342 Corporate bonds 1,563,313 82,823 (1,293 ) (1,653 ) 1,643,190 Total fixed maturities 9,590,337 818,218 (5,015 ) (3,911 ) 10,399,629 Equity securities: Insurance, banks and other financial institutions 835,144 769,505 (12,641 ) — 1,592,008 Industrial, consumer and all other 1,555,040 1,270,474 (21,953 ) — 2,803,561 Total equity securities 2,390,184 2,039,979 (34,594 ) — 4,395,569 Short-term investments 1,995,368 124 (1 ) — 1,995,491 Investments, available-for-sale $ 13,975,889 $ 2,858,321 $ (39,610 ) $ (3,911 ) $ 16,790,689 December 31, 2015 (dollars in thousands) Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Unrealized Other-Than- Temporary Impairment Losses Estimated Fair Value Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ 695,652 $ 9,836 $ (4,781 ) $ — $ 700,707 Obligations of states, municipalities and political subdivisions 3,817,136 204,302 (8,225 ) — 4,013,213 Foreign governments 1,302,329 115,809 (1,681 ) — 1,416,457 Commercial mortgage-backed securities 657,670 6,867 (4,999 ) — 659,538 Residential mortgage-backed securities 837,964 22,563 (4,022 ) (2,258 ) 854,247 Asset-backed securities 36,462 15 (406 ) — 36,071 Corporate bonds 1,690,945 41,123 (16,209 ) (1,624 ) 1,714,235 Total fixed maturities 9,038,158 400,515 (40,323 ) (3,882 ) 9,394,468 Equity securities: Insurance, banks and other financial institutions 651,002 690,271 (6,551 ) — 1,334,722 Industrial, consumer and all other 1,557,832 1,227,052 (45,131 ) — 2,739,753 Total equity securities 2,208,834 1,917,323 (51,682 ) — 4,074,475 Short-term investments 1,642,103 167 (9 ) — 1,642,261 Investments, available-for-sale $ 12,889,095 $ 2,318,005 $ (92,014 ) $ (3,882 ) $ 15,111,204
Summary Of Gross Unrealized Investment Losses By Length Of Time That Securities Have Continuously Been In An Unrealized Loss Position	December 31, 2015 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ 427,003 $ (3,648 ) $ 92,552 $ (1,133 ) $ 519,555 $ (4,781 ) Obligations of states, municipalities and political subdivisions 169,362 (4,864 ) 70,101 (3,361 ) 239,463 (8,225 ) Foreign governments 51,328 (249 ) 40,345 (1,432 ) 91,673 (1,681 ) Commercial mortgage-backed securities 289,058 (3,600 ) 95,843 (1,399 ) 384,901 (4,999 ) Residential mortgage-backed securities 78,814 (2,858 ) 137,100 (3,422 ) 215,914 (6,280 ) Asset-backed securities 6,228 (54 ) 24,315 (352 ) 30,543 (406 ) Corporate bonds 470,694 (9,509 ) 343,737 (8,324 ) 814,431 (17,833 ) Total fixed maturities 1,492,487 (24,782 ) 803,993 (19,423 ) 2,296,480 (44,205 ) Equity securities: Insurance, banks and other financial institutions 63,873 (6,384 ) 6,247 (167 ) 70,120 (6,551 ) Industrial, consumer and all other 344,857 (44,879 ) 2,907 (252 ) 347,764 (45,131 ) Total equity securities 408,730 (51,263 ) 9,154 (419 ) 417,884 (51,682 ) Short-term investments 129,473 (9 ) — — 129,473 (9 ) Total $ 2,030,690 $ (76,054 ) $ 813,147 $ (19,842 ) $ 2,843,837 $ (95,896 ) The following tables summarize gross unrealized investment losses by the length of time that securities have continuously been in an unrealized loss position. June 30, 2016 Less than 12 months 12 months or longer Total (dollars in thousands) Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Estimated Fair Value Gross Unrealized Holding and Other-Than- Temporary Impairment Losses Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ 7,537 $ (7 ) $ 8,529 $ (2 ) $ 16,066 $ (9 ) Obligations of states, municipalities and political subdivisions 2,789 (2 ) 47,301 (2,327 ) 50,090 (2,329 ) Foreign governments 42,255 (304 ) 5,026 (1 ) 47,281 (305 ) Commercial mortgage-backed securities 23,518 (142 ) 63,738 (391 ) 87,256 (533 ) Residential mortgage-backed securities 6,584 (2,304 ) 104,340 (483 ) 110,924 (2,787 ) Asset-backed securities — — 6,316 (17 ) 6,316 (17 ) Corporate bonds 37,222 (1,664 ) 104,194 (1,282 ) 141,416 (2,946 ) Total fixed maturities 119,905 (4,423 ) 339,444 (4,503 ) 459,349 (8,926 ) Equity securities: Insurance, banks and other financial institutions 77,737 (12,641 ) — — 77,737 (12,641 ) Industrial, consumer and all other 191,170 (19,887 ) 27,819 (2,066 ) 218,989 (21,953 ) Total equity securities 268,907 (32,528 ) 27,819 (2,066 ) 296,726 (34,594 ) Short-term investments 99,977 (1 ) — — 99,977 (1 ) Total $ 488,789 $ (36,952 ) $ 367,263 $ (6,569 ) $ 856,052 $ (43,521 )
Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturities By Contractual Maturity Date	The amortized cost and estimated fair value of fixed maturities at June 30, 2016 are shown below by contractual maturity. (dollars in thousands) Amortized Cost Estimated Fair Value Due in one year or less $ 720,305 $ 726,444 Due after one year through five years 1,386,900 1,441,314 Due after five years through ten years 1,654,425 1,802,966 Due after ten years 4,019,238 4,517,015 7,780,868 8,487,739 Commercial mortgage-backed securities 975,606 1,023,604 Residential mortgage-backed securities 805,631 859,944 Asset-backed securities 28,232 28,342 Total fixed maturities $ 9,590,337 $ 10,399,629
Components Of Net Investment Income	The following table presents the components of net investment income. Quarter Ended June 30, Six Months Ended June 30, (dollars in thousands) 2016 2015 2016 2015 Interest: Municipal bonds (tax-exempt) $ 22,563 $ 24,293 $ 44,485 $ 50,145 Municipal bonds (taxable) 16,222 14,150 32,110 28,250 Other taxable bonds 36,959 34,013 72,278 69,151 Short-term investments, including overnight deposits 2,654 1,116 4,945 2,367 Dividends on equity securities 16,758 18,633 34,410 37,657 Income from equity method investments 3,921 1,712 3,668 3,056 Other 190 479 2,674 540 99,267 94,396 194,570 191,166 Investment expenses (4,271 ) (3,810 ) (8,280 ) (7,705 ) Net investment income $ 94,996 $ 90,586 $ 186,290 $ 183,461
Summary Of Net Realized Investment Gains And The Change In Net Unrealized Gains On Investments	The following table presents net realized investment gains and the change in net unrealized gains on investments. Quarter Ended June 30, Six Months Ended June 30, (dollars in thousands) 2016 2015 2016 2015 Realized gains: Sales of fixed maturities $ 699 $ 770 $ 967 $ 2,338 Sales of equity securities 17,798 7,000 45,526 22,956 Other 353 1,739 773 2,413 Total realized gains 18,850 9,509 47,266 27,707 Realized losses: Sales of fixed maturities (142 ) (97 ) (555 ) (221 ) Sales of equity securities (1,780 ) (113 ) (2,498 ) (272 ) Other-than-temporary impairments (3,675 ) — (12,080 ) (5,092 ) Other (718 ) (16 ) (2,996 ) (227 ) Total realized losses (6,315 ) (226 ) (18,129 ) (5,812 ) Gains (losses) on securities measured at fair value through net income 4,706 (3,178 ) 9,283 (10,219 ) Net realized investment gains $ 17,241 $ 6,105 $ 38,420 $ 11,676 Change in net unrealized gains on investments included in other comprehensive income (loss): Fixed maturities $ 213,026 $ (286,551 ) $ 452,982 $ (180,213 ) Equity securities 42,786 (64,792 ) 139,744 (6,447 ) Short-term investments 32 11 (35 ) (9 ) Net increase (decrease) $ 255,844 $ (351,332 ) $ 592,691 $ (186,669 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Balances Of Assets And Liabilities Measured At Fair Value On A Recurring Basis	The following tables present the balances of assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy. June 30, 2016 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments available-for-sale: Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ — $ 700,281 $ — $ 700,281 Obligations of states, municipalities and political subdivisions — 4,561,049 — 4,561,049 Foreign governments — 1,583,219 — 1,583,219 Commercial mortgage-backed securities — 1,023,604 — 1,023,604 Residential mortgage-backed securities — 859,944 — 859,944 Asset-backed securities — 28,342 — 28,342 Corporate bonds — 1,643,190 — 1,643,190 Total fixed maturities — 10,399,629 — 10,399,629 Equity securities: Insurance, banks and other financial institutions 1,408,485 — 183,523 1,592,008 Industrial, consumer and all other 2,803,561 — — 2,803,561 Total equity securities 4,212,046 — 183,523 4,395,569 Short-term investments 1,877,297 118,194 — 1,995,491 Total investments available-for-sale $ 6,089,343 $ 10,517,823 $ 183,523 $ 16,790,689 December 31, 2015 (dollars in thousands) Level 1 Level 2 Level 3 Total Assets: Investments available-for-sale: Fixed maturities: U.S. Treasury securities and obligations of U.S. government agencies $ — $ 700,707 $ — $ 700,707 Obligations of states, municipalities and political subdivisions — 4,013,213 — 4,013,213 Foreign governments — 1,416,457 — 1,416,457 Commercial mortgage-backed securities — 659,538 — 659,538 Residential mortgage-backed securities — 854,247 — 854,247 Asset-backed securities — 36,071 — 36,071 Corporate bonds — 1,714,235 — 1,714,235 Total fixed maturities — 9,394,468 — 9,394,468 Equity securities: Insurance, banks and other financial institutions 1,334,722 — — 1,334,722 Industrial, consumer and all other 2,739,753 — — 2,739,753 Total equity securities 4,074,475 — — 4,074,475 Short-term investments 1,529,924 112,337 — 1,642,261 Total investments available-for-sale $ 5,604,399 $ 9,506,805 $ — $ 15,111,204
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 June 30, Six Months Ended June 30, (dollars in thousands) 2016 2015 2016 2015 Equity securities, beginning of period $ 176,942 $ — $ — $ — Purchases 25,000 — 195,250 — Sales (25,000 ) — (25,000 ) — Total gains included in: Net income 6,581 — 13,273 — Other comprehensive income (loss) — — — — Transfers into Level 3 — — — — Transfers out of Level 3 — — — — Equity securities, end of period $ 183,523 $ — $ 183,523 $ — Net unrealized gains included in net income relating to assets held at June 30, 2016 and 2015 (1) $ 6,581 $ — $ 13,273 $ — (1) Included in net realized investment gains in the consolidated statements of income and comprehensive income (loss).

Segment Reporting Disclosures (

Segment Reporting Disclosures (Tables)	6 Months Ended
	Jun. 30, 2016
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Company's Segment Disclosures	The following tables summarize the Company's segment disclosures. Quarter Ended June 30, 2016 (dollars in thousands) U.S. Insurance International Insurance Reinsurance Other Insurance (Discontinued Lines) Investing Consolidated Gross premium volume $ 689,468 $ 318,581 $ 269,604 $ (4 ) $ — $ 1,277,649 Net written premiums 579,233 244,636 226,681 (4 ) — 1,050,546 Earned premiums 533,328 203,052 214,514 (35 ) — 950,859 Losses and loss adjustment expenses: Current accident year (352,092 ) (146,453 ) (152,693 ) — — (651,238 ) Prior accident years 66,332 39,002 34,644 (296 ) — 139,682 Underwriting, acquisition and insurance expenses (212,915 ) (96,562 ) (66,143 ) 40 — (375,580 ) Underwriting profit (loss) 34,653 (961 ) 30,322 (291 ) — 63,723 Net investment income — — — — 94,996 94,996 Net realized investment gains — — — — 17,241 17,241 Other revenues (insurance) 958 609 — 446 — 2,013 Other expenses (insurance) (684 ) (2,137 ) — (7,199 ) — (10,020 ) Segment profit (loss) $ 34,927 $ (2,489 ) $ 30,322 $ (7,044 ) $ 112,237 $ 167,953 Other revenues (non-insurance) 310,828 Other expenses (non-insurance) (267,889 ) Amortization of intangible assets (17,204 ) Interest expense (33,697 ) Loss on early extinguishment of debt (44,100 ) Income before income taxes $ 115,891 U.S. GAAP combined ratio (1) 94 % 100 % 86 % NM (2) 93 % Quarter Ended June 30, 2015 (dollars in thousands) U.S. Insurance International Insurance Reinsurance Other Insurance (Discontinued Lines) Investing Consolidated Gross premium volume $ 668,853 $ 338,159 $ 258,745 $ 29 $ — $ 1,265,786 Net written premiums 554,638 264,129 215,520 57 — 1,034,344 Earned premiums 520,446 223,941 213,140 30 — 957,557 Losses and loss adjustment expenses: Current accident year (341,335 ) (168,896 ) (154,623 ) — — (664,854 ) Prior accident years 68,620 43,373 15,118 1,549 — 128,660 Underwriting, acquisition and insurance expenses (211,856 ) (94,617 ) (73,170 ) (9 ) — (379,652 ) Underwriting profit 35,875 3,801 465 1,570 — 41,711 Net investment income — — — — 90,586 90,586 Net realized investment gains — — — — 6,105 6,105 Other revenues (insurance) 2,203 915 469 350 — 3,937 Other expenses (insurance) (1,284 ) (1,318 ) — (3,348 ) — (5,950 ) Segment profit (loss) $ 36,794 $ 3,398 $ 934 $ (1,428 ) $ 96,691 $ 136,389 Other revenues (non-insurance) 246,420 Other expenses (non-insurance) (236,286 ) Amortization of intangible assets (16,949 ) Interest expense (29,288 ) Income before income taxes $ 100,286 U.S. GAAP combined ratio (1) 93 % 98 % 100 % NM (2) 96 % (1) 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. (2) NM – Ratio is not meaningful. Six Months Ended June 30, 2016 (dollars in thousands) U.S. Insurance International Insurance Reinsurance Other Insurance (Discontinued Lines) Investing Consolidated Gross premium volume $ 1,337,258 $ 609,985 $ 723,090 $ (21 ) $ — $ 2,670,312 Net written premiums 1,131,978 471,035 629,407 86 — 2,232,506 Earned premiums 1,065,796 418,397 424,133 219 — 1,908,545 Losses and loss adjustment expenses: Current accident year (668,425 ) (291,929 ) (283,169 ) — — (1,243,523 ) Prior accident years 104,986 68,654 71,005 13,358 — 258,003 Underwriting, acquisition and insurance expenses (410,378 ) (185,168 ) (144,648 ) (74 ) — (740,268 ) Underwriting profit 91,979 9,954 67,321 13,503 — 182,757 Net investment income — — — — 186,290 186,290 Net realized investment gains — — — — 38,420 38,420 Other revenues (insurance) 2,377 4,730 — 941 — 8,048 Other expenses (insurance) (1,408 ) (3,691 ) — (15,200 ) — (20,299 ) Segment profit (loss) $ 92,948 $ 10,993 $ 67,321 $ (756 ) $ 224,710 $ 395,216 Other revenues (non-insurance) 610,816 Other expenses (non-insurance) (532,703 ) Amortization of intangible assets (34,464 ) Interest expense (64,538 ) Loss on early extinguishment of debt (44,100 ) Income before income taxes $ 330,227 U.S. GAAP combined ratio (1) 91 % 98 % 84 % NM (2) 90 % Six Months Ended June 30, 2015 (dollars in thousands) U.S. Insurance International Insurance Reinsurance Other Insurance (Discontinued Lines) Investing Consolidated Gross premium volume $ 1,254,218 $ 627,386 $ 636,582 $ 73 $ — $ 2,518,259 Net written premiums 1,050,807 486,837 531,732 398 — 2,069,774 Earned premiums 1,035,000 429,902 435,894 411 — 1,901,207 Losses and loss adjustment expenses: Current accident year (658,092 ) (317,740 ) (303,363 ) — — (1,279,195 ) Prior accident years 136,201 120,023 41,505 (1,723 ) — 296,006 Underwriting, acquisition and insurance expenses (397,116 ) (173,411 ) (149,723 ) (87 ) — (720,337 ) Underwriting profit (loss) 115,993 58,774 24,313 (1,399 ) — 197,681 Net investment income — — — — 183,461 183,461 Net realized investment gains — — — — 11,676 11,676 Other revenues (insurance) 3,605 6,302 892 327 — 11,126 Other expenses (insurance) (2,189 ) (2,722 ) — (10,697 ) — (15,608 ) Segment profit (loss) $ 117,409 $ 62,354 $ 25,205 $ (11,769 ) $ 195,137 $ 388,336 Other revenues (non-insurance) 499,289 Other expenses (non-insurance) (457,629 ) Amortization of intangible assets (31,589 ) Interest expense (58,600 ) Income before income taxes $ 339,807 U.S. GAAP combined ratio (1) 89 % 86 % 94 % NM (2) 90 % (1) 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. (2) 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) June 30, 2016 December 31, 2015 Segment assets: Investing $ 18,976,263 $ 18,056,947 Underwriting 5,822,696 5,385,126 Total segment assets 24,798,959 23,442,073 Non-insurance operations 1,536,669 1,497,042 Total assets $ 26,335,628 $ 24,939,115

Other Revenues And Other Expe26

Other Revenues And Other Expenses (Tables)	6 Months Ended
	Jun. 30, 2016
Other Income and Expenses [Abstract]
Summary Of Other Revenues And Other Expenses By Component	The following tables summarize the components of other revenues and other expenses. Quarter Ended June 30, 2016 2015 (dollars in thousands) Other Revenues Other Expenses Other Revenues Other Expenses Insurance: Managing general agent operations $ 1,567 $ 2,821 $ 3,118 $ 2,602 Life and annuity 446 7,199 350 3,348 Other — — 469 — 2,013 10,020 3,937 5,950 Non-Insurance: Markel Ventures: Manufacturing 193,152 159,227 174,141 168,580 Markel Ventures: Non-Manufacturing 104,602 91,685 65,412 63,013 Investment management 7,350 10,836 — — Other 5,724 6,141 6,867 4,693 310,828 267,889 246,420 236,286 Total $ 312,841 $ 277,909 $ 250,357 $ 242,236 Six Months Ended June 30, 2016 2015 (dollars in thousands) Other Revenues Other Expenses Other Revenues Other Expenses Insurance: Managing general agent operations $ 7,107 $ 5,099 $ 8,988 $ 4,911 Life and annuity 941 15,200 327 10,697 Other — — 1,811 — 8,048 20,299 11,126 15,608 Non-Insurance: Markel Ventures: Manufacturing 385,843 319,593 351,903 320,380 Markel Ventures: Non-Manufacturing 198,430 180,118 133,093 126,843 Investment management 14,523 20,766 — — Other 12,020 12,226 14,293 10,406 610,816 532,703 499,289 457,629 Total $ 618,864 $ 553,002 $ 510,415 $ 473,237

Reinsurance (Tables)

Reinsurance (Tables)	6 Months Ended
	Jun. 30, 2016
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 June 30, 2016 2015 (dollars in thousands) Written Earned Written Earned Direct $ 957,244 $ 865,943 $ 951,885 $ 875,376 Assumed 320,405 295,868 313,901 304,324 Ceded (227,103 ) (210,952 ) (231,442 ) (222,143 ) Net premiums $ 1,050,546 $ 950,859 $ 1,034,344 $ 957,557 Six Months Ended June 30, 2016 2015 (dollars in thousands) Written Earned Written Earned Direct $ 1,836,332 $ 1,733,387 $ 1,753,465 $ 1,719,946 Assumed 833,980 585,931 764,794 617,159 Ceded (437,806 ) (410,773 ) (448,485 ) (435,898 ) Net premiums $ 2,232,506 $ 1,908,545 $ 2,069,774 $ 1,901,207

Net Income Per Share (Tables)

Net Income Per Share (Tables)	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Schedule Of Net Income 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 June 30, Six Months Ended June 30, (in thousands, except per share amounts) 2016 2015 2016 2015 Net income to shareholders $ 78,797 $ 91,369 $ 239,167 $ 282,361 Adjustment of redeemable noncontrolling interests (2,529 ) 3,062 (5,981 ) 1,715 Adjusted net income to shareholders $ 76,268 $ 94,431 $ 233,186 $ 284,076 Basic common shares outstanding 14,012 13,975 14,003 13,973 Dilutive potential common shares from conversion of options 4 9 5 10 Dilutive potential common shares from conversion of restricted stock 72 68 79 74 Diluted shares outstanding 14,088 14,052 14,087 14,057 Basic net income per share $ 5.44 $ 6.76 $ 16.65 $ 20.33 Diluted net income per share $ 5.41 $ 6.72 $ 16.55 $ 20.21

Other Comprehensive Income (L29

Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2016
Other Comprehensive Income (Loss), Tax [Abstract]
Change In Accumulated Other Comprehensive Income By Component, Net Of Taxes And Noncontrolling Interest	The following table presents the change in accumulated other comprehensive income by component, net of taxes and noncontrolling interests, for the six months ended June 30, 2016 and 2015 . (dollars in thousands) Unrealized Holding Gains on Available-for-Sale Securities Foreign Currency Net Actuarial Pension Loss Total December 31, 2014 $ 1,793,254 $ (43,491 ) $ (45,206 ) $ 1,704,557 Other comprehensive loss before reclassifications (109,001 ) (11,373 ) — (120,374 ) Amounts reclassified from accumulated other comprehensive income (14,037 ) — 932 (13,105 ) Total other comprehensive income (loss) (123,038 ) (11,373 ) 932 (133,479 ) June 30, 2015 $ 1,670,216 $ (54,864 ) $ (44,274 ) $ 1,571,078 December 31, 2015 $ 1,472,762 $ (72,696 ) $ (45,558 ) $ 1,354,508 Other comprehensive income before reclassifications 388,273 2,189 — 390,462 Amounts reclassified from accumulated other comprehensive income (23,550 ) — 857 (22,693 ) Total other comprehensive income 364,723 2,189 857 367,769 June 30, 2016 $ 1,837,485 $ (70,507 ) $ (44,701 ) $ 1,722,277
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 June 30, Six Months Ended June 30, (dollars in thousands) 2016 2015 2016 2015 Change in net unrealized gains on investments: Net holding gains (losses) arising during the period $ 71,381 $ (113,579 ) $ 187,880 $ (57,997 ) Change in unrealized other-than-temporary impairment losses on fixed maturities arising during the period 9 (3 ) (6 ) 38 Reclassification adjustments for net gains included in net income (2,333 ) (2,576 ) (7,810 ) (5,672 ) Change in net unrealized gains on investments 69,057 (116,158 ) 180,064 (63,631 ) Change in foreign currency translation adjustments (1,618 ) 1,872 (1,695 ) 833 Change in net actuarial pension loss 86 117 188 233 Total $ 67,525 $ (114,169 ) $ 178,557 $ (62,565 )
Reclassifications From Accumulated Other Comprehensive Income Into Income, By Component	The following table presents the details of amounts reclassified from accumulated other comprehensive income into income, by component. Quarter Ended June 30, Six Months Ended June 30, (dollars in thousands) 2016 2015 2016 2015 Unrealized holding gains on available-for-sale securities: Other-than-temporary impairment losses $ (3,675 ) $ — $ (12,080 ) $ (5,092 ) Net realized investment gains, excluding other-than-temporary impairment losses 16,575 7,560 43,440 24,801 Total before taxes 12,900 7,560 31,360 19,709 Income taxes (2,333 ) (2,576 ) (7,810 ) (5,672 ) Reclassification of unrealized holding gains, net of taxes $ 10,567 $ 4,984 $ 23,550 $ 14,037 Net actuarial pension loss: Underwriting, acquisition and insurance expenses $ (480 ) $ (586 ) $ (1,045 ) $ (1,165 ) Income taxes 86 117 188 233 Reclassification of net actuarial pension loss, net of taxes $ (394 ) $ (469 ) $ (857 ) $ (932 )

Recent Accounting Pronounceme30

Recent Accounting Pronouncements (Narrative) (Details) $ in Millions	Dec. 31, 2015USD ($)
Accounting Standards Update 2015-03 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance costs reclassified from other assets to senior long-term debt and other debt	$ 2.2

Acquisitions (Narrative) (Detai

Acquisitions (Narrative) (Details) - CapTech Ventures Inc [Member] - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Dec. 31, 2015	Mar. 31, 2016
Business Acquisition [Line Items]
Percentage acquired	80.00%
Total consideration	$ 60.6
Material adjustments to the provisional estimates recorded		$ 0

Investments (Narrative) (Detail

Investments (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016USD ($)securities	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)securities	Jun. 30, 2015USD ($)securities	Dec. 31, 2015USD ($)securities
Schedule of Investments [Line Items]
Available-for-sale securities in unrealized loss position, number of positions | securities	216		216		659
Available-for-sale securities, estimated fair value	$ 856,052		$ 856,052		$ 2,843,837
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	$ (43,521)		$ (43,521)		$ (95,896)
Number of available-for-sale securities positions in a continuous unrealized loss position for one year or longer at period end | securities	126		126		271
Available-for-sale securities, estimated fair value, 12 months or longer	$ 367,263		$ 367,263		$ 813,147
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(6,569)		(6,569)		(19,842)
Other-than-temporary impairment losses recognized in net income	(3,675)	$ 0	(12,080)	$ (5,092)
Fixed Maturities [Member]
Schedule of Investments [Line Items]
Available-for-sale securities, estimated fair value	459,349		459,349		2,296,480
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	$ (8,926)		$ (8,926)		$ (44,205)
Number of available-for-sale securities positions in a continuous unrealized loss position for one year or longer at period end | securities	119		119		264
Available-for-sale securities, estimated fair value, 12 months or longer	$ 339,444		$ 339,444		$ 803,993
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(4,503)		(4,503)		(19,423)
Equity Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale securities, estimated fair value	296,726		296,726		417,884
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	$ (34,594)		$ (34,594)		$ (51,682)
Number of available-for-sale securities positions in a continuous unrealized loss position for one year or longer at period end | securities	7		7		7
Available-for-sale securities, estimated fair value, 12 months or longer	$ 27,819		$ 27,819		$ 9,154
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(2,066)		(2,066)		(419)
Other-than-temporary impairment losses recognized in net income	$ (3,700)		$ (12,100)	$ (5,100)
Other than temporary impairment losses recognized in earnings, number of investment positions | securities	12		21	10
Industrial, Consumer And All Other [Member]
Schedule of Investments [Line Items]
Available-for-sale securities, estimated fair value	$ 218,989		$ 218,989		347,764
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(21,953)		(21,953)		(45,131)
Available-for-sale securities, estimated fair value, 12 months or longer	27,819		27,819		2,907
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(2,066)		(2,066)		(252)
Other-than-temporary impairment losses recognized in net income	(3,000)		(10,800)	$ (4,500)
Insurance, Banks And Other Financial Institutions [Member]
Schedule of Investments [Line Items]
Available-for-sale securities, estimated fair value	77,737		77,737		70,120
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(12,641)		(12,641)		(6,551)
Available-for-sale securities, estimated fair value, 12 months or longer	0		0		6,247
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	0		0		$ (167)
Other-than-temporary impairment losses recognized in net income	$ (600)		$ (1,300)	$ (600)

Investments (Available-For-Sale

Investments (Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	$ 13,975,889	$ 12,889,095
Available-for-sale investments, gross unrealized holding gains	2,858,321	2,318,005
Available-for-sale investments, gross unrealized holding losses	(39,610)	(92,014)
Available-for-sale investments, unrealized other-than-temporary impairment losses	(3,911)	(3,882)
Available-for-sale investments, estimated fair value	16,790,689	15,111,204
U.S. Treasury Securities And Obligations Of U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	674,801	695,652
Available-for-sale investments, gross unrealized holding gains	25,489	9,836
Available-for-sale investments, gross unrealized holding losses	(9)	(4,781)
Available-for-sale investments, unrealized other-than-temporary impairment losses	0	0
Available-for-sale investments, estimated fair value	700,281	700,707
Obligations Of States, Municipalities And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	4,193,114	3,817,136
Available-for-sale investments, gross unrealized holding gains	370,264	204,302
Available-for-sale investments, gross unrealized holding losses	(2,329)	(8,225)
Available-for-sale investments, unrealized other-than-temporary impairment losses	0	0
Available-for-sale investments, estimated fair value	4,561,049	4,013,213
Foreign Governments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	1,349,640	1,302,329
Available-for-sale investments, gross unrealized holding gains	233,884	115,809
Available-for-sale investments, gross unrealized holding losses	(305)	(1,681)
Available-for-sale investments, unrealized other-than-temporary impairment losses	0	0
Available-for-sale investments, estimated fair value	1,583,219	1,416,457
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	975,606	657,670
Available-for-sale investments, gross unrealized holding gains	48,531	6,867
Available-for-sale investments, gross unrealized holding losses	(533)	(4,999)
Available-for-sale investments, unrealized other-than-temporary impairment losses	0	0
Available-for-sale investments, estimated fair value	1,023,604	659,538
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	805,631	837,964
Available-for-sale investments, gross unrealized holding gains	57,100	22,563
Available-for-sale investments, gross unrealized holding losses	(529)	(4,022)
Available-for-sale investments, unrealized other-than-temporary impairment losses	(2,258)	(2,258)
Available-for-sale investments, estimated fair value	859,944	854,247
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	28,232	36,462
Available-for-sale investments, gross unrealized holding gains	127	15
Available-for-sale investments, gross unrealized holding losses	(17)	(406)
Available-for-sale investments, unrealized other-than-temporary impairment losses	0	0
Available-for-sale investments, estimated fair value	28,342	36,071
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	1,563,313	1,690,945
Available-for-sale investments, gross unrealized holding gains	82,823	41,123
Available-for-sale investments, gross unrealized holding losses	(1,293)	(16,209)
Available-for-sale investments, unrealized other-than-temporary impairment losses	(1,653)	(1,624)
Available-for-sale investments, estimated fair value	1,643,190	1,714,235
Total Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	9,590,337	9,038,158
Available-for-sale investments, gross unrealized holding gains	818,218	400,515
Available-for-sale investments, gross unrealized holding losses	(5,015)	(40,323)
Available-for-sale investments, unrealized other-than-temporary impairment losses	(3,911)	(3,882)
Available-for-sale investments, estimated fair value	10,399,629	9,394,468
Insurance, Banks And Other Financial Institutions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	835,144	651,002
Available-for-sale investments, gross unrealized holding gains	769,505	690,271
Available-for-sale investments, gross unrealized holding losses	(12,641)	(6,551)
Available-for-sale investments, unrealized other-than-temporary impairment losses	0	0
Available-for-sale investments, estimated fair value	1,592,008	1,334,722
Industrial, Consumer And All Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	1,555,040	1,557,832
Available-for-sale investments, gross unrealized holding gains	1,270,474	1,227,052
Available-for-sale investments, gross unrealized holding losses	(21,953)	(45,131)
Available-for-sale investments, unrealized other-than-temporary impairment losses	0	0
Available-for-sale investments, estimated fair value	2,803,561	2,739,753
Total Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	2,390,184	2,208,834
Available-for-sale investments, gross unrealized holding gains	2,039,979	1,917,323
Available-for-sale investments, gross unrealized holding losses	(34,594)	(51,682)
Available-for-sale investments, unrealized other-than-temporary impairment losses	0	0
Available-for-sale investments, estimated fair value	4,395,569	4,074,475
Short-Term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments, amortized cost	1,995,368	1,642,103
Available-for-sale investments, gross unrealized holding gains	124	167
Available-for-sale investments, gross unrealized holding losses	(1)	(9)
Available-for-sale investments, unrealized other-than-temporary impairment losses	0	0
Available-for-sale investments, estimated fair value	$ 1,995,491	$ 1,642,261

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	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	$ 488,789	$ 2,030,690
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(36,952)	(76,054)
Available-for-sale securities, estimated fair value, 12 months or longer	367,263	813,147
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(6,569)	(19,842)
Available-for-sale securities, estimated fair value	856,052	2,843,837
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(43,521)	(95,896)
U.S. Treasury Securities And Obligations Of U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	7,537	427,003
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(7)	(3,648)
Available-for-sale securities, estimated fair value, 12 months or longer	8,529	92,552
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(2)	(1,133)
Available-for-sale securities, estimated fair value	16,066	519,555
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(9)	(4,781)
Obligations Of States, Municipalities And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	2,789	169,362
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(2)	(4,864)
Available-for-sale securities, estimated fair value, 12 months or longer	47,301	70,101
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(2,327)	(3,361)
Available-for-sale securities, estimated fair value	50,090	239,463
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(2,329)	(8,225)
Foreign Governments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	42,255	51,328
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(304)	(249)
Available-for-sale securities, estimated fair value, 12 months or longer	5,026	40,345
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(1)	(1,432)
Available-for-sale securities, estimated fair value	47,281	91,673
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(305)	(1,681)
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	23,518	289,058
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(142)	(3,600)
Available-for-sale securities, estimated fair value, 12 months or longer	63,738	95,843
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(391)	(1,399)
Available-for-sale securities, estimated fair value	87,256	384,901
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(533)	(4,999)
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	6,584	78,814
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(2,304)	(2,858)
Available-for-sale securities, estimated fair value, 12 months or longer	104,340	137,100
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(483)	(3,422)
Available-for-sale securities, estimated fair value	110,924	215,914
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(2,787)	(6,280)
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	0	6,228
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	0	(54)
Available-for-sale securities, estimated fair value, 12 months or longer	6,316	24,315
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(17)	(352)
Available-for-sale securities, estimated fair value	6,316	30,543
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(17)	(406)
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	37,222	470,694
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(1,664)	(9,509)
Available-for-sale securities, estimated fair value, 12 months or longer	104,194	343,737
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(1,282)	(8,324)
Available-for-sale securities, estimated fair value	141,416	814,431
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(2,946)	(17,833)
Total Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	119,905	1,492,487
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(4,423)	(24,782)
Available-for-sale securities, estimated fair value, 12 months or longer	339,444	803,993
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(4,503)	(19,423)
Available-for-sale securities, estimated fair value	459,349	2,296,480
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(8,926)	(44,205)
Insurance, Banks And Other Financial Institutions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	77,737	63,873
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(12,641)	(6,384)
Available-for-sale securities, estimated fair value, 12 months or longer	0	6,247
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	0	(167)
Available-for-sale securities, estimated fair value	77,737	70,120
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(12,641)	(6,551)
Industrial, Consumer And All Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	191,170	344,857
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(19,887)	(44,879)
Available-for-sale securities, estimated fair value, 12 months or longer	27,819	2,907
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(2,066)	(252)
Available-for-sale securities, estimated fair value	218,989	347,764
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(21,953)	(45,131)
Total Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	268,907	408,730
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(32,528)	(51,263)
Available-for-sale securities, estimated fair value, 12 months or longer	27,819	9,154
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	(2,066)	(419)
Available-for-sale securities, estimated fair value	296,726	417,884
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	(34,594)	(51,682)
Short-Term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, estimated fair value, less than 12 months	99,977	129,473
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, less than 12 months	(1)	(9)
Available-for-sale securities, estimated fair value, 12 months or longer	0	0
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses, 12 months or longer	0	0
Available-for-sale securities, estimated fair value	99,977	129,473
Available-for-sale securities, gross unrealized holding and other-than-temporary impairment losses	$ (1)	$ (9)

Investments (Schedule Of Amorti

Investments (Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturities By Contractual Maturity Date) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, amortized cost	$ 720,305
Due after one year through five years, amortized cost	1,386,900
Due after five years through ten years, amortized cost	1,654,425
Due after ten years, amortized cost	4,019,238
Amortized cost, sub-total	7,780,868
Total fixed maturities, amortized cost	9,590,337	$ 9,038,158
Due in one year or less, estimated fair value	726,444
Due after one year through five years, estimated fair value	1,441,314
Due after five years through ten years, estimated fair value	1,802,966
Due after ten years, estimated fair value	4,517,015
Estimated fair value, sub-total	8,487,739
Total fixed maturities, estimated fair value	10,399,629	$ 9,394,468
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, amortized cost	975,606
Fixed maturities, estimated fair value	1,023,604
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, amortized cost	805,631
Fixed maturities, estimated fair value	859,944
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, amortized cost	28,232
Fixed maturities, estimated fair value	$ 28,342

Investments (Components Of Net

Investments (Components Of Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Municipal bonds (tax-exempt)	$ 22,563	$ 24,293	$ 44,485	$ 50,145
Short-term investments, including overnight deposits	2,654	1,116	4,945	2,367
Dividends on equity securities	16,758	18,633	34,410	37,657
Income from equity method investments	3,921	1,712	3,668	3,056
Other	190	479	2,674	540
Total investment income	99,267	94,396	194,570	191,166
Investment expenses	(4,271)	(3,810)	(8,280)	(7,705)
Net investment income	94,996	90,586	186,290	183,461
Taxable Municipal Bonds [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Taxable bonds	16,222	14,150	32,110	28,250
Other Taxable Bonds [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Taxable bonds	$ 36,959	$ 34,013	$ 72,278	$ 69,151

Investments (Summary Of Net Rea

Investments (Summary Of Net Realized Investment Gains (Losses) And The Change In Net Unrealized Gains On Investments) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Gain (Loss) on Investments [Line Items]
Realized gains	$ 18,850	$ 9,509	$ 47,266	$ 27,707
Realized losses	(6,315)	(226)	(18,129)	(5,812)
Gains (losses) on securities measured at fair value through net income	4,706	(3,178)	9,283	(10,219)
Other-than-temporary impairment losses recognized in net income	(3,675)	0	(12,080)	(5,092)
Net realized investment gains	17,241	6,105	38,420	11,676
Change in net unrealized gains on investments	255,844	(351,332)	592,691	(186,669)
Sales Of Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Realized gains	699	770	967	2,338
Realized losses	(142)	(97)	(555)	(221)
Sales Of Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Realized gains	17,798	7,000	45,526	22,956
Realized losses	(1,780)	(113)	(2,498)	(272)
Other [Member]
Gain (Loss) on Investments [Line Items]
Realized gains	353	1,739	773	2,413
Realized losses	(718)	(16)	(2,996)	(227)
Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Change in net unrealized gains on investments	213,026	(286,551)	452,982	(180,213)
Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Other-than-temporary impairment losses recognized in net income	(3,700)		(12,100)	(5,100)
Change in net unrealized gains on investments	42,786	(64,792)	139,744	(6,447)
Short-Term Investments [Member]
Gain (Loss) on Investments [Line Items]
Change in net unrealized gains on investments	$ 32	$ 11	$ (35)	$ (9)

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair value, level 1 to level 2 transfers, amount	$ 0	$ 0	$ 0	$ 0
Fair value, level 2 to level 1 transfers, amount	0	0	0	0
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 And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	$ 10,399,629	$ 9,394,468
Total equity securities	4,395,569	4,074,475
Short-term investments	1,995,491	1,642,261
Available-for-sale investments, estimated fair value	16,790,689	15,111,204
Fixed Maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	10,399,629	9,394,468
U.S. Treasury Securities And Obligations Of U.S. Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	700,281	700,707
Obligations Of States, Municipalities And Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	4,561,049	4,013,213
Foreign Governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	1,583,219	1,416,457
Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	1,023,604	659,538
Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	859,944	854,247
Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	28,342	36,071
Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	1,643,190	1,714,235
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	4,395,569	4,074,475
Insurance, Banks And Other Financial Institutions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	1,592,008	1,334,722
Industrial, Consumer And All Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments, estimated fair value	2,803,561	2,739,753
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	10,399,629	9,394,468
Total equity securities	4,395,569	4,074,475
Short-term investments	1,995,491	1,642,261
Available-for-sale investments, estimated fair value	16,790,689	15,111,204
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Total equity securities	4,212,046	4,074,475
Short-term investments	1,877,297	1,529,924
Available-for-sale investments, estimated fair value	6,089,343	5,604,399
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	10,399,629	9,394,468
Total equity securities	0	0
Short-term investments	118,194	112,337
Available-for-sale investments, estimated fair value	10,517,823	9,506,805
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Total equity securities	183,523	0
Short-term investments	0	0
Available-for-sale investments, estimated fair value	183,523	0
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities And Obligations Of U.S. Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	700,281	700,707
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities And Obligations Of U.S. Government Agencies [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities And Obligations Of U.S. Government Agencies [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	700,281	700,707
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities And Obligations Of U.S. Government Agencies [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Obligations Of States, Municipalities And Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	4,561,049	4,013,213
Fair Value, Measurements, 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]
Total fixed maturities	0	0
Fair Value, Measurements, 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]
Total fixed maturities	4,561,049	4,013,213
Fair Value, Measurements, 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]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Foreign Governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	1,583,219	1,416,457
Fair Value, Measurements, Recurring [Member] | Foreign Governments [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Foreign Governments [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	1,583,219	1,416,457
Fair Value, Measurements, Recurring [Member] | Foreign Governments [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	1,023,604	659,538
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	1,023,604	659,538
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	859,944	854,247
Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	859,944	854,247
Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	28,342	36,071
Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	28,342	36,071
Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	1,643,190	1,714,235
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	1,643,190	1,714,235
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturities	0	0
Fair Value, Measurements, Recurring [Member] | Insurance, Banks And Other Financial Institutions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	1,592,008	1,334,722
Fair Value, Measurements, 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]
Total equity securities	1,408,485	1,334,722
Fair Value, Measurements, 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]
Total equity securities	0	0
Fair Value, Measurements, 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]
Total equity securities	183,523	0
Fair Value, Measurements, Recurring [Member] | Industrial, Consumer And All Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	2,803,561	2,739,753
Fair Value, Measurements, Recurring [Member] | Industrial, Consumer And All Other [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	2,803,561	2,739,753
Fair Value, Measurements, Recurring [Member] | Industrial, Consumer And All Other [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Industrial, Consumer And All Other [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total 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		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Equity securities, beginning of period		$ 176,942	$ 0	$ 0	$ 0
Purchases		25,000	0	195,250	0
Sales		(25,000)	0	(25,000)	0
Total gains included in net income		6,581	0	13,273	0
Total gains included in other comprehensive income (loss)		0	0	0	0
Transfers into level 3		0	0	0	0
Transfers out of level 3		0	0	0	0
Equity securities, end of period		183,523	0	183,523	0
Net unrealized gains included in net income relating to assets held at June 30, 2016 and 2015	[1]	$ 6,581	$ 0	$ 13,273	$ 0
[1]	Included in net realized investment gains in the consolidated statements of income and comprehensive income (loss).

Segment Reporting Disclosures41

Segment Reporting Disclosures (Company's Segment Disclosures) (Details) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)segment	Jun. 30, 2015USD ($)
Segment Reporting Information [Line Items]
Number of reportable ongoing underwriting segments | segment				3
Gross premium volume		$ 1,277,649	$ 1,265,786	$ 2,670,312	$ 2,518,259
Net written premiums		1,050,546	1,034,344	2,232,506	2,069,774
Earned premiums		950,859	957,557	1,908,545	1,901,207
Losses and loss adjustment expenses, current accident year		(651,238)	(664,854)	(1,243,523)	(1,279,195)
Losses and loss adjustment expenses, prior accident years		139,682	128,660	258,003	296,006
Underwriting, acquisition and insurance expenses		(375,580)	(379,652)	(740,268)	(720,337)
Underwriting profit (loss)		63,723	41,711	182,757	197,681
Net investment income		94,996	90,586	186,290	183,461
Net realized investment gains		17,241	6,105	38,420	11,676
Other revenues (insurance)		2,013	3,937	8,048	11,126
Other expenses (insurance)		(10,020)	(5,950)	(20,299)	(15,608)
Segment profit (loss)		167,953	136,389	395,216	388,336
Other revenues (non-insurance)		310,828	246,420	610,816	499,289
Other expenses (non-insurance)		(267,889)	(236,286)	(532,703)	(457,629)
Amortization of intangible assets		(17,204)	(16,949)	(34,464)	(31,589)
Interest expense		(33,697)	(29,288)	(64,538)	(58,600)
Loss on early extinguishment of debt		(44,100)	0	(44,100)	0
Income Before Income Taxes		$ 115,891	$ 100,286	$ 330,227	$ 339,807
U.S. GAAP combined ratio	[1]	93.00%	96.00%	90.00%	90.00%
U.S. Insurance [Member]
Segment Reporting Information [Line Items]
Gross premium volume		$ 689,468	$ 668,853	$ 1,337,258	$ 1,254,218
Net written premiums		579,233	554,638	1,131,978	1,050,807
Earned premiums		533,328	520,446	1,065,796	1,035,000
Losses and loss adjustment expenses, current accident year		(352,092)	(341,335)	(668,425)	(658,092)
Losses and loss adjustment expenses, prior accident years		66,332	68,620	104,986	136,201
Underwriting, acquisition and insurance expenses		(212,915)	(211,856)	(410,378)	(397,116)
Underwriting profit (loss)		34,653	35,875	91,979	115,993
Net investment income		0	0	0	0
Net realized investment gains		0	0	0	0
Other revenues (insurance)		958	2,203	2,377	3,605
Other expenses (insurance)		(684)	(1,284)	(1,408)	(2,189)
Segment profit (loss)		$ 34,927	$ 36,794	$ 92,948	$ 117,409
U.S. GAAP combined ratio	[1]	94.00%	93.00%	91.00%	89.00%
International Insurance [Member]
Segment Reporting Information [Line Items]
Gross premium volume		$ 318,581	$ 338,159	$ 609,985	$ 627,386
Net written premiums		244,636	264,129	471,035	486,837
Earned premiums		203,052	223,941	418,397	429,902
Losses and loss adjustment expenses, current accident year		(146,453)	(168,896)	(291,929)	(317,740)
Losses and loss adjustment expenses, prior accident years		39,002	43,373	68,654	120,023
Underwriting, acquisition and insurance expenses		(96,562)	(94,617)	(185,168)	(173,411)
Underwriting profit (loss)		(961)	3,801	9,954	58,774
Net investment income		0	0	0	0
Net realized investment gains		0	0	0	0
Other revenues (insurance)		609	915	4,730	6,302
Other expenses (insurance)		(2,137)	(1,318)	(3,691)	(2,722)
Segment profit (loss)		$ (2,489)	$ 3,398	$ 10,993	$ 62,354
U.S. GAAP combined ratio	[1]	100.00%	98.00%	98.00%	86.00%
Reinsurance [Member]
Segment Reporting Information [Line Items]
Gross premium volume		$ 269,604	$ 258,745	$ 723,090	$ 636,582
Net written premiums		226,681	215,520	629,407	531,732
Earned premiums		214,514	213,140	424,133	435,894
Losses and loss adjustment expenses, current accident year		(152,693)	(154,623)	(283,169)	(303,363)
Losses and loss adjustment expenses, prior accident years		34,644	15,118	71,005	41,505
Underwriting, acquisition and insurance expenses		(66,143)	(73,170)	(144,648)	(149,723)
Underwriting profit (loss)		30,322	465	67,321	24,313
Net investment income		0	0	0	0
Net realized investment gains		0	0	0	0
Other revenues (insurance)		0	469	0	892
Other expenses (insurance)		0	0	0	0
Segment profit (loss)		$ 30,322	$ 934	$ 67,321	$ 25,205
U.S. GAAP combined ratio	[1]	86.00%	100.00%	84.00%	94.00%
Other Insurance (Discontinued Lines) [Member]
Segment Reporting Information [Line Items]
Gross premium volume		$ (4)	$ 29	$ (21)	$ 73
Net written premiums		(4)	57	86	398
Earned premiums		(35)	30	219	411
Losses and loss adjustment expenses, current accident year		0	0	0	0
Losses and loss adjustment expenses, prior accident years		(296)	1,549	13,358	(1,723)
Underwriting, acquisition and insurance expenses		40	(9)	(74)	(87)
Underwriting profit (loss)		(291)	1,570	13,503	(1,399)
Net investment income		0	0	0	0
Net realized investment gains		0	0	0	0
Other revenues (insurance)		446	350	941	327
Other expenses (insurance)		(7,199)	(3,348)	(15,200)	(10,697)
Segment profit (loss)		$ (7,044)	$ (1,428)	$ (756)	$ (11,769)
U.S. GAAP combined ratio - not meaniningful	[1],[2]	NM	NM	NM	NM
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
Underwriting, acquisition and insurance expenses		0	0	0	0
Underwriting profit (loss)		0	0	0	0
Net investment income		94,996	90,586	186,290	183,461
Net realized investment gains		17,241	6,105	38,420	11,676
Other revenues (insurance)		0	0	0	0
Other expenses (insurance)		0	0	0	0
Segment profit (loss)		$ 112,237	$ 96,691	$ 224,710	$ 195,137
[1]	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.
[2]	NM – Ratio is not meaningful.

Segment Reporting Disclosures42

Segment Reporting Disclosures (Reconciliation Of Segment Assets To The Company's Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Assets	$ 26,335,628	$ 24,939,115
Non-Insurance Operations [Member]
Segment Reporting Information [Line Items]
Assets	1,536,669	1,497,042
Segment Assets [Member]
Segment Reporting Information [Line Items]
Assets	24,798,959	23,442,073
Segment Assets [Member] | Investing [Member]
Segment Reporting Information [Line Items]
Assets	18,976,263	18,056,947
Segment Assets [Member] | Underwriting [Member]
Segment Reporting Information [Line Items]
Assets	$ 5,822,696	$ 5,385,126

Senior Long-Term Debt (Narrativ

Senior Long-Term Debt (Narrative) (Details) - USD ($) $ in Thousands	May 05, 2016	Apr. 05, 2016	Apr. 30, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Debt Instrument [Line Items]
Loss on early extinguishment of debt				$ (44,100)	$ 0	$ (44,100)	$ 0
5.0% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 100,000	$ 400,000
Debt instrument, interest rate	5.00%	5.00%
Net proceeds from issuance of unsecured senior notes	$ 100,800	$ 392,300
7.35% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate			7.35%
Debt instrument, repurchased face amount			$ 70,200
Early repayment of senior debt			$ 95,000
7.125% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate			7.125%
Debt instrument, repurchased face amount			$ 108,800
Early repayment of senior debt			$ 126,400
7.20% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate				7.20%		7.20%
Debt instrument, principal amount outstanding				$ 90,600		$ 90,600

Other Revenues And Other Expe44

Other Revenues And Other Expenses (Summary Of Other Revenues And Other Expenses By Component) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Other Revenues and Other Expenses [Line Items]
Other revenues	$ 312,841	$ 250,357	$ 618,864	$ 510,415
Other expenses	277,909	242,236	553,002	473,237
Insurance Operations [Member]
Other Revenues and Other Expenses [Line Items]
Other revenues	2,013	3,937	8,048	11,126
Other expenses	10,020	5,950	20,299	15,608
Non-Insurance Operations [Member]
Other Revenues and Other Expenses [Line Items]
Other revenues	310,828	246,420	610,816	499,289
Other expenses	267,889	236,286	532,703	457,629
Managing General Agent Operations [Member] | Insurance Operations [Member]
Other Revenues and Other Expenses [Line Items]
Other revenues	1,567	3,118	7,107	8,988
Other expenses	2,821	2,602	5,099	4,911
Life And Annuity [Member] | Insurance Operations [Member]
Other Revenues and Other Expenses [Line Items]
Other revenues	446	350	941	327
Other expenses	7,199	3,348	15,200	10,697
Other Insurance [Member] | Insurance Operations [Member]
Other Revenues and Other Expenses [Line Items]
Other revenues	0	469	0	1,811
Other expenses	0	0	0	0
Manufacturing [Member] | Non-Insurance Operations [Member] | Markel Ventures Operations [Member]
Other Revenues and Other Expenses [Line Items]
Other revenues	193,152	174,141	385,843	351,903
Other expenses	159,227	168,580	319,593	320,380
Non-Manufacturing [Member] | Non-Insurance Operations [Member] | Markel Ventures Operations [Member]
Other Revenues and Other Expenses [Line Items]
Other revenues	104,602	65,412	198,430	133,093
Other expenses	91,685	63,013	180,118	126,843
Investment Management [Member] | Non-Insurance Operations [Member]
Other Revenues and Other Expenses [Line Items]
Other revenues	7,350	0	14,523	0
Other expenses	10,836	0	20,766	0
Other Non-Insurance [Member] | Non-Insurance Operations [Member]
Other Revenues and Other Expenses [Line Items]
Other revenues	5,724	6,867	12,020	14,293
Other expenses	$ 6,141	$ 4,693	$ 12,226	$ 10,406

Reinsurance (Narrative) (Detail

Reinsurance (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reinsurance Disclosures [Abstract]
Percentage of ceded earned premiums to gross earned premiums	18.00%	19.00%	18.00%	19.00%
Percentage of assumed earned premiums to net earned premiums	31.00%	32.00%	31.00%	32.00%
Reinsurance recoverables	$ 75.5	$ 143.3	$ 206.1	$ 232.1

Reinsurance (Effect Of Reinsura

Reinsurance (Effect Of Reinsurance And Retrocessional Reinsurance On Premiums Written And Earned) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reinsurance Disclosures [Abstract]
Direct premiums written	$ 957,244	$ 951,885	$ 1,836,332	$ 1,753,465
Direct premiums earned	865,943	875,376	1,733,387	1,719,946
Assumed premiums written	320,405	313,901	833,980	764,794
Assumed premiums earned	295,868	304,324	585,931	617,159
Ceded premiums written	(227,103)	(231,442)	(437,806)	(448,485)
Ceded premiums earned	(210,952)	(222,143)	(410,773)	(435,898)
Net premiums written	1,050,546	1,034,344	2,232,506	2,069,774
Net premiums earned	$ 950,859	$ 957,557	$ 1,908,545	$ 1,901,207

Life And Annuity Benefits (Narr

Life And Annuity Benefits (Narrative) (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2016USD ($)	Jun. 30, 2016USD ($)
Liability for Future Policy Benefits [Abstract]
Increase in life and annuity benefits	$ 47.9	$ 47.9
Cumulative adjustment to life and annuity benefits	$ 47.9	$ 47.9

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details)	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Income Tax Disclosure [Abstract]
Effective tax rate	26.00%	16.00%
U.S. statutory tax rate	35.00%	35.00%
Favorable impact due to recognition of foreign tax credits		12.00%

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details) $ in Millions	Jun. 30, 2016USD ($)
Variable Interest Entity [Line Items]
Total investment and insurance assets under management of MCIM for unconsolidated VIEs	$ 3,400
Other Fund [Member]
Variable Interest Entity [Line Items]
Investment in one of the unconsolidated Funds	25.2
Markel Diversified Fund [Member]
Variable Interest Entity [Line Items]
Total assets of the Markel Diversified Fund	161.8
Total liabilities of the Markel Diversified Fund	63.9
Investment in one of the unconsolidated Funds	$ 158.3
Percentage of total assets of the Markel Diversified Fund invested in one of the unconsolidated Funds	6.00%
Note payable included in total liabilities of the Markel Diversified Fund delivered as part of the consideration provided for its investment	$ 62.5

Net Income Per Share (Schedule

Net Income Per Share (Schedule Of Net Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Line Items]
Net income to shareholders	$ 78,797	$ 91,369	$ 239,167	$ 282,361
Adjustment of redeemable noncontrolling interests	(2,529)	3,062	(5,981)	1,715
Adjusted net income to shareholders	$ 76,268	$ 94,431	$ 233,186	$ 284,076
Basic common shares outstanding	14,012	13,975	14,003	13,973
Diluted shares outstanding	14,088	14,052	14,087	14,057
Basic net income per share	$ 5.44	$ 6.76	$ 16.65	$ 20.33
Diluted net income per share	$ 5.41	$ 6.72	$ 16.55	$ 20.21
Stock Options [Member]
Earnings Per Share [Line Items]
Dilutive potential common shares	4	9	5	10
Restricted Stock Units (RSUs) [Member]
Earnings Per Share [Line Items]
Dilutive potential common shares	72	68	79	74

Other Comprehensive Income (L51

Other Comprehensive Income (Loss) (Change In Accumulated Other Comprehensive Income By Component, Net Of Taxes And Noncontrolling Interest) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income, beginning balance	$ 1,354,508	$ 1,704,557
Other comprehensive income (loss) before reclassifications	390,462	(120,374)
Amounts reclassified from accumulated other comprehensive income	(22,693)	(13,105)
Total other comprehensive income (loss)	367,769	(133,479)
Accumulated other comprehensive income, ending balance	1,722,277	1,571,078
Unrealized Holding Gains On Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income, beginning balance	1,472,762	1,793,254
Other comprehensive income (loss) before reclassifications	388,273	(109,001)
Amounts reclassified from accumulated other comprehensive income	(23,550)	(14,037)
Total other comprehensive income (loss)	364,723	(123,038)
Accumulated other comprehensive income, ending balance	1,837,485	1,670,216
Foreign Currency [Member]
Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income, beginning balance	(72,696)	(43,491)
Other comprehensive income (loss) before reclassifications	2,189	(11,373)
Amounts reclassified from accumulated other comprehensive income	0	0
Total other comprehensive income (loss)	2,189	(11,373)
Accumulated other comprehensive income, ending balance	(70,507)	(54,864)
Net Actuarial Pension Loss [Member]
Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income, beginning balance	(45,558)	(45,206)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income	857	932
Total other comprehensive income (loss)	857	932
Accumulated other comprehensive income, ending balance	$ (44,701)	$ (44,274)

Other Comprehensive Income (L52

Other Comprehensive Income (Loss) (Summary Of Tax Expense (Benefit) Of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Other Comprehensive Income (Loss), Tax [Abstract]
Net holding gains (losses) arising during the period	$ 71,381	$ (113,579)	$ 187,880	$ (57,997)
Change in unrealized other-than-temporary impairment losses on fixed maturities arising during the period	9	(3)	(6)	38
Reclassification adjustments for net gains included in net income	(2,333)	(2,576)	(7,810)	(5,672)
Change in net unrealized gains on investments	69,057	(116,158)	180,064	(63,631)
Change in foreign currency translation adjustments	(1,618)	1,872	(1,695)	833
Change in net actuarial pension loss	86	117	188	233
Total	$ 67,525	$ (114,169)	$ 178,557	$ (62,565)

Other Comprehensive Income (L53

Other Comprehensive Income (Loss) (Reclassifications From Accumulated Other Comprehensive Income Into Income, By Component) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairment losses recognized in net income	$ (3,675)	$ 0	$ (12,080)	$ (5,092)
Net realized investment gains, excluding other-than-temporary impairment losses	20,916	6,105	50,500	16,768
Income Before Income Taxes	115,891	100,286	330,227	339,807
Underwriting, acquisition and insurance expenses	(375,580)	(379,652)	(740,268)	(720,337)
Income taxes	(35,218)	(7,833)	(85,908)	(53,348)
Net Income	80,673	92,453	244,319	286,459
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]
Other-than-temporary impairment losses recognized in net income	(3,675)	0	(12,080)	(5,092)
Net realized investment gains, excluding other-than-temporary impairment losses	16,575	7,560	43,440	24,801
Income Before Income Taxes	12,900	7,560	31,360	19,709
Income taxes	(2,333)	(2,576)	(7,810)	(5,672)
Net Income	10,567	4,984	23,550	14,037
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	(480)	(586)	(1,045)	(1,165)
Income taxes	86	117	188	233
Net Income	$ (394)	$ (469)	$ (857)	$ (932)