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Schedule V - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Premiums receivable from underwriting activities |  |  |
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] |  |  |
Balance at Beginning of Year | $ 23.0 | $ 16.2 | $ 5.2
Charged to Costs and Expenses | 11.0 | 6.8 | 11.0
Charged to Other Accounts | 0.0 | 0.0 | 0.0
Deductions | 0.0 | 0.0 | 0.0
Balance at End of Year | 34.0 | 23.0 | 16.2
Reinsurance |  |  |
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] |  |  |
Balance at Beginning of Year | 0.0 | 0.0 | 0.0
Charged to Costs and Expenses | 0.0 |  |
Charged to Other Accounts | 0.0 | 0.0 | 0.0
Deductions | 0.0 | 0.0 | 0.0
Balance at End of Year | $ 0.0 | $ 0.0 | $ 0.0

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- Definition Amount of valuation and qualifying accounts and reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
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