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SCHEDULE VI SUPPLEMENTAL INFORMATION FOR PROPERTY AND CASUALTY INSURANCE UNDERWRITERS | 12 Months Ended
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Dec. 31, 2022
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Abstract] |
SCHEDULE VI SUPPLEMENTAL INFORMATION FOR PROPERTY AND CASUALTY INSURANCE UNDERWRITERS | WHITE MOUNTAINS INSURANCE GROUP, LTD. SUPPLEMENTAL INFORMATION FOR PROPERTY AND CASUALTY INSURANCE UNDERWRITERS (Millions)
Column A |  | Column B |  | Column C |  | Column D |  | Column E |  | Column F |  | Column G |  | Column H |  | Column I |  | Column J |  | Column K
|  | Deferred acquisition costs |  | Reserves for Unpaid Claims and Claims Adjustment Expenses |  | Discount, if any, deducted in Column C |  | Unearned Premiums |  | Earned Premiums |  | Net investment income |  | Claims and Claims Adjustment Expenses Incurred Related to |  | Amortization of deferred policy acquisition costs |  | Paid Claims and Claims Adjustment Expenses |  | Premiums written
Affiliation with registrant |  |  |  |  |  |  |  | Current Year |  | Prior Year |  |  |
Ark: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2022 |  | $ | 127.2 |  |  | $ | 1,296.5 |  |  | — |  |  | $ | 623.2 |  |  | $ | 1,043.4 |  |  | $ | 16.3 |  |  | $ | 588.1 |  |  | $ | (51.7) |  |  | $ | 238.3 |  |  | $ | 257.5 |  |  | $ | 1,195.2 |
2021 |  | 100.8 |  |  | 894.7 |  |  | — |  |  | 495.9 |  |  | 637.3 |  |  | 2.9 |  |  | 336.3 |  |  | (21.5) |  |  | 111.3 |  |  | — |  |  | 859.1 |

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- Definition The entire disclosure of supplemental information for registrant, its subsidiary and 50-percent-or-less-owned equity basis investee, with liability for property-casualty insurance claim. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12 -Subsection 18 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-18) -URI https://asc.fasb.org/extlink&oid=120401096&loc=d3e575016-122915 + Details
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- References No definition available. + Details
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