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Goodwill And Intangible Assets Goodwill And Intangible Assets (Components of Net Intangible Assets) (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Intangible [Line Items] |  |  |  |  |  |  |
Net intangible assets, beginning balance |  | $ 1,747,464 |  | $ 1,822,486 |  |  |
Acquisitions |  |  |  | 21,614 |  |  |
Dispositions |  | (2,000) |  | (2,716) |  |  |
Amortization of intangible assets |  | (180,614) | [1] | (178,778) | [2] | $ (160,539) | [3]
Adjustments to preliminary purchase price allocation |  | 22,671 |  | 86,773 |  |  |
Foreign currency movements and other adjustments |  | 1,163 |  | (1,915) |  |  |
Net intangible assets, ending balance |  | 1,588,684 |  | 1,747,464 |  | 1,822,486 |
Underwriting [Member] |  |  |  |  |  |  |
Intangible [Line Items] |  |  |  |  |  |  |
Net intangible assets, beginning balance | [4] | 362,322 |  | 401,255 |  |  |
Acquisitions | [4] |  |  | 0 |  |  |
Dispositions |  | 0 | [4] | 0 |  |  |
Amortization of intangible assets |  | 37,076 | [4] | 38,533 | [4] | 41,200 |
Adjustments to preliminary purchase price allocation |  | 0 | [4] | 0 |  |  |
Foreign currency movements and other adjustments | [4] | 98 |  | (400) |  |  |
Net intangible assets, ending balance | [4] | 325,344 |  | 362,322 |  | 401,255 |
Markel Ventures [Member] |  |  |  |  |  |  |
Intangible [Line Items] |  |  |  |  |  |  |
Net intangible assets, beginning balance |  | 796,297 |  | 766,179 |  |  |
Acquisitions |  |  |  | 21,614 |  |  |
Dispositions |  | 0 |  | 0 |  |  |
Amortization of intangible assets |  | (82,370) | [1] | (79,043) | [2] | (57,568) | [3]
Adjustments to preliminary purchase price allocation |  | 22,671 |  | 86,773 |  |  |
Foreign currency movements and other adjustments |  | 119 |  | 774 |  |  |
Net intangible assets, ending balance |  | 736,717 |  | 796,297 |  | 766,179 |
Other Operations [Member] |  |  |  |  |  |  |
Intangible [Line Items] |  |  |  |  |  |  |
Net intangible assets, beginning balance | [5] | 588,845 |  | 655,052 |  |  |
Acquisitions | [5] |  |  | 0 |  |  |
Dispositions |  | (2,000) | [5] | (2,716) |  |  |
Amortization of intangible assets | [5] | (61,168) |  | (61,202) |  |  |
Adjustments to preliminary purchase price allocation |  | 0 | [5] | 0 |  |  |
Foreign currency movements and other adjustments | [5] | 946 |  | (2,289) |  |  |
Net intangible assets, ending balance | [5] | $ 526,623 |  | $ 588,845 |  | $ 655,052 |
[1] | Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets attributable to the Company's underwriting segments, included in Other, was $37.1 million for the year ended December 31, 2023.
[2] | Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets attributable to the Company's underwriting segments, included in Other, was $38.5 million for the year ended December 31, 2022.
[3] | Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets attributable to the Company's underwriting segments, included in Other, was $41.2 million for the year ended December 31, 2021.
[4] | Amounts included in Underwriting reflect the intangible assets associated with the Company's underwriting segments, which are not allocated between the Insurance and Reinsurance segments.
[5] | Amounts included in Other reflect the Company's operations that are not included in a reportable segment and are primarily related to the Company's program services and insurance-linked securities operations.

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