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Reinsurance (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Feb. 05, 2021
Ceded Credit Risk [Line Items] |  |  |  |
Funds held under reinsurance agreements, liability | $ 3,700 | $ 4,000 |  | $ 690
Largest recoverable from single reinsurer | 5,416 | 5,463 |  |
Reinsurance recoveries reported in insurance claims and policyholders' benefits reported on the Consolidated Statement of Operations | 2,631 | 3,058 | $ 3,158 |
Subsidiaries of Berkshire Hathaway Group |  |  |  |
Ceded Credit Risk [Line Items] |  |  |  |
Largest recoverable from single reinsurer | 1,900 |  |  |
Cavello Bay Reinsurance Limited |  |  |  |
Ceded Credit Risk [Line Items] |  |  |  |
Largest recoverable from single reinsurer | 598 |  |  |
Gateway Rivers Insurance Company |  |  |  |
Ceded Credit Risk [Line Items] |  |  |  |
Largest recoverable from single reinsurer | 446 |  |  |
Significant Captive Program |  |  |  |
Ceded Credit Risk [Line Items] |  |  |  |
Direct and ceded earned premiums | 3,270 | 3,638 | 3,543 |
Reinsurance recoveries reported in insurance claims and policyholders' benefits reported on the Consolidated Statement of Operations | $ 1,796 | $ 2,003 | $ 2,375 |

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- Definition Amount of reduction of provision for policy benefits and costs incurred for policies ceded. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI https://asc.fasb.org/extlink&oid=99397103&loc=d3e6811-158387 + Details
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- Definition Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(6)) -URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 5 -URI https://asc.fasb.org/extlink&oid=99397103&loc=d3e6824-158387 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 45 -Paragraph 5 -URI https://asc.fasb.org/extlink&oid=99404803&loc=d3e21409-158489 + Details
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