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Weighted-Average Exercise Price Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] United States Treasury securities and agencies US Treasury and Government [Member] Schedule of Restricted Cash and Restricted Cash Equivalents Restrictions on Cash and Cash Equivalents [Table Text Block] Entity Address, State or Province Entity Address, State or Province Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Security, Excluded EPS Calculation [Table] Effects of Reinsurance [Line Items] Effects of Reinsurance [Line Items] Balances held in the trust Regulatory Asset Requirement, Special Deposits, Held In Trust Regulatory Asset Requirement, Special Deposits, Held In Trust Individual: Individual [Axis] Vesting [Axis] Vesting [Axis] Root Reinsurance Company, Ltd. 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[Member] Root Reinsurance Company, Ltd. 2020 Equity Incentive Plan 2020 Equity Incentive Plan [Member] 2020 Equity Incentive Plan Investments: Investments [Abstract] Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Insurance Disclosure [Text Block] Document Fiscal Year Focus Document Fiscal Year Focus Schedule of Direct Premiums Written Schedule of Gross Premiums Written Effects of Reinsurance [Table Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Effective income tax rate (as percent) 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