Consolidated Statements Of Income (Loss) And Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021		Mar. 31, 2020
OPERATING REVENUES
Earned premiums	$ 1,497,695		$ 1,330,709
Net investment income	96,570		88,243
Net investment gains (losses)	526,871		(1,681,441)
Products revenues	328,832		352,161
Services and other revenues	450,226		245,994
Total Operating Revenues	2,900,194		335,666
OPERATING EXPENSES
Losses and loss adjustment expenses	879,918		1,076,348
Underwriting, acquisition and insurance expenses	526,743		495,163
Products expenses	296,526		314,071
Services and other expenses	412,097		217,556
Amortization of intangible assets	39,553	[1]	37,858	[2]
Total Operating Expenses	2,154,837		2,140,996
Operating Income	745,357		(1,805,330)
Interest expense	(42,389)		(45,030)
Net foreign exchange gains	25,084		78,301
Income (Loss) Before Income Taxes	728,052		(1,772,059)
Income tax (expense) benefit	(148,371)		370,683
Net Income (Loss)	579,681		(1,401,376)
Net income attributable to noncontrolling interests	(5,987)		(4,387)
Net Income (Loss) to Shareholders	573,694		(1,405,763)
Preferred stock dividends	0		0
Net Income (Loss) to Common Stockholders	573,694		(1,405,763)
OTHER COMPREHENSIVE INCOME
Net holding gains (losses) arising during the period	(214,376)		64,377
Reclassification adjustments for net gains (losses) included in net income (loss)	(88)		1,187
Change in net unrealized gains on available-for-sale investments, net of taxes	(214,464)		65,564
Change in foreign currency translation adjustments, net of taxes	(808)		(12,734)
Change in net actuarial pension loss, net of taxes	592		0
Total Other Comprehensive Income (Loss)	(214,680)		52,830
Comprehensive Income (Loss)	365,001		(1,348,546)
Comprehensive income attributable to noncontrolling interests	(6,004)		(4,263)
Comprehensive Income (Loss) to Shareholders	$ 358,997		$ (1,352,809)
NET INCOME (LOSS) PER COMMON SHARE
Basic (in dollars per share)	$ 42.09		$ (100.60)
Diluted (in dollars per share)	$ 42.02		$ (100.60)

[1] Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to the Company's Insurance and Reinsurance segments.

[2] Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to the Company's Insurance and Reinsurance segments.