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Unpaid Loss and Loss Adjustment Expense - Additional Information (Details) - USD ($) |  |  | 1 Months Ended | 3 Months Ended
--- | --- | --- | --- | ---
Jul. 01, 2024 | Jul. 01, 2023 | Mar. 31, 2025 | Mar. 31, 2025 | Mar. 31, 2024
Effects of Reinsurance [Line Items] |  |  |  |  |
Favorable development on net loss and LAE reserves |  |  |  | $ (10,400,000) | $ (6,500,000)
Current accident year incurred loss and LAE |  |  |  | 95,800,000 | $ 72,400,000
Reinsurance, excess retention, amount reinsured, per event | $ 10,000,000 | $ 5,000,000 |  |  |
Reinsurance, per risk limit, amount |  | 750,000 |  |  |
Reinsurance Contract [Axis]: Excess of Loss Reinsurance Contract |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |
Reinsurance, excess retention, amount reinsured, per event |  | 80,000,000 |  |  |
Initial limit for each loss occurrence |  | 50,000,000,000,000 |  |  |
Reinsurance Contract [Axis]: Property Per Risk Excess of Loss Reinsurance |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |
Reinsurance, excess retention, amount reinsured, per policy |  | $ 2,250,000 |  |  |
Reinsurance, excess retention, percentage |  | 100.00% |  |  |
Reinsurance Contract [Axis]: Proportional Reinsurance Contracts |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |
Percent of contracts subject to participation through reinsurance |  | 55.00% |  |  |
Lemonade Insurance Company | Reinsurance Contract [Axis]: Automatic Facultative Property Per Risk Excess of Loss |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |
Reinsurance, excess retention, amount reinsured, per policy |  | $ 3,000,000 |  |  |
Lemonade Insurance Company | Reinsurance Contract [Axis]: Automatic Facultative Property Per Risk Excess of Loss Reinsurance |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |
Reinsurance, excess retention, amount reinsured, per policy |  | $ 10,000,000 |  |  |
Reinsurance, excess retention, percentage |  | 100.00% |  |  |
Maximum | Reinsurance Contract [Axis]: Property Per Risk Excess of Loss Reinsurance |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |
Reinsurance, excess retention, amount reinsured, per policy |  | $ 750,000 |  |  |
California Wildfires |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |
Current accident year incurred loss and LAE |  |  |  | $ 16,800,000 |
Reduction in net unpaid losses |  |  | $ 4,200,000 |  |

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- Definition Amount, after effects of reinsurance, of increase (decrease) in the liability for unpaid claims and claims adjustment expense. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-3 + Details
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