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Reinsurance (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Ceded Credit Risk [Line Items] |  |  |
Funds held under reinsurance agreements, liability | $ 2,900 | $ 3,000 |
Reinsurance recoveries reported in insurance claims and policyholders' benefits reported on the Consolidated Statement of Operations | 3,085 | 3,016 | $ 2,601
Subsidiaries of Berkshire Hathaway Group |  |  |
Ceded Credit Risk [Line Items] |  |  |
Largest recoverables from single reinsurer | 2,100 |  |
Gateway Rivers Insurance Company |  |  |
Ceded Credit Risk [Line Items] |  |  |
Largest recoverables from single reinsurer | 395 |  |
Subsidiaries of Wilton Re |  |  |
Ceded Credit Risk [Line Items] |  |  |
Largest recoverables from single reinsurer | 230 |  |
Significant Captive Program |  |  |
Ceded Credit Risk [Line Items] |  |  |
Direct and ceded earned premiums | 3,864 | 3,865 | 3,344
Reinsurance recoveries reported in insurance claims and policyholders' benefits reported on the Consolidated Statement of Operations | $ 2,541 | $ 2,621 | $ 2,282

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- Definition Direct and ceded earned premiums related to business that is one hundred percent reinsured as a result of a significant captive program + References No definition available. + Details
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- Definition Largest Recoverables from Single Reinsurer + References No definition available. + Details
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- Definition Amount of funds held as security for payments to be received under reinsurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.13(c)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition Amount of reduction of provision for policy benefits and costs incurred for policies ceded. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6811-158387 + Details
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