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Third-Party Reinsurance - Remaining Gross and Net Reinsurance Recoverables (Details) - All Entities Except TCP Providers - USD ($) $ in Millions | Mar. 31, 2023 | Dec. 31, 2022
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Reinsurance [Line Items] |  |
Reinsurance recoverables |  | $ 372.0
Reinsurance Recoverables, Collateral |  | 103.2
Net Reinsurance Recoverables |  | $ 268.8
Percent of reinsurance recoverables from insurers that are collateralized |  | 100.00%
A+ or better |  |
Reinsurance [Line Items] |  |
Reinsurance recoverables | $ 173.8 |
Reinsurance Recoverables, Collateral | 0.0 |
Net Reinsurance Recoverables | $ 173.8 |
Percent of reinsurance recoverables from insurers that are collateralized | 64.70% |
A- to A |  |
Reinsurance [Line Items] |  |
Reinsurance recoverables | $ 77.9 |
Reinsurance Recoverables, Collateral | 0.0 |
Net Reinsurance Recoverables | $ 77.9 |
Percent of reinsurance recoverables from insurers that are collateralized | 29.00% |
B++ or lower and not rated |  |
Reinsurance [Line Items] |  |
Reinsurance recoverables | $ 120.3 |
Reinsurance Recoverables, Collateral | 103.2 |
Net Reinsurance Recoverables | $ 17.1 |
Percent of reinsurance recoverables from insurers that are collateralized | 6.30% |

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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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919253-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953401-111524 + Details
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