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Reinsurance (Reinsurance Recoverable by Category and Listing of Largest Reinsurers) (Details) - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Ceded Credit Risk [Line Items] |  |
Gross reinsurance recoverable | $ 15,497 |
Provision | $ 316 | $ 323
% of Gross | 2.00% |
Largest reinsurers |  |
Ceded Credit Risk [Line Items] |  |
Gross reinsurance recoverable | $ 6,594 |
Provision | $ 72 |
% of Gross | 1.10% |
Other reinsurers balances rated A- or better |  |
Ceded Credit Risk [Line Items] |  |
Gross reinsurance recoverable | $ 4,624 |
Provision | $ 55 |
% of Gross | 1.20% |
Other reinsurers balances with ratings lower than A- or not rated |  |
Ceded Credit Risk [Line Items] |  |
Gross reinsurance recoverable | $ 478 |
Provision | $ 70 |
% of Gross | 14.60% |
Other pools and government agencies |  |
Ceded Credit Risk [Line Items] |  |
Gross reinsurance recoverable | $ 379 |
Provision | $ 15 |
% of Gross | 4.00% |
Structured settlements |  |
Ceded Credit Risk [Line Items] |  |
Gross reinsurance recoverable | $ 535 |
Provision | $ 15 |
% of Gross | 2.80% |
Other captives |  |
Ceded Credit Risk [Line Items] |  |
Gross reinsurance recoverable | $ 2,647 |
Provision | $ 20 |
% of Gross | 0.80% |
Other |  |
Ceded Credit Risk [Line Items] |  |
Gross reinsurance recoverable | $ 240 |
Provision | $ 69 |
% of Gross | 28.80% |

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- Definition Amount of allowance for credit loss on reinsurance recoverable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118955202&loc=SL82895884-210446 + Details
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- Definition Amount before valuation allowance recoverable 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 No definition available. + Details
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