| Pay vs Performance Disclosure | 12 Months Ended |
| Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) |
| Pay vs Performance Disclosure [Table] | | | |
| Pay vs Performance [Table Text Block] | Year Summary Compensation Table Total for PEO (1) Compensation Actually Paid to PEO (1)(2) Average Summary Compensation Table Total for Non-PEO NEOs (3) Average Compensation Actually Paid to Non-PEO NEOs (2)(3) Value of Initial Fixed $100 Investment Based On: Net Income Growth in Fully Diluted Book Value per Share (5) Total Shareholder Return Peer Group Total Shareholder Return (4) (a) (b) (c) (d) (e) (f) (g) (h) (i) 2022 $2,610,610 $2,916,755 $841,738 $912,266 $80.61 $150.34 $25,342 4.3% 2021 $3,114,210 $2,974,247 $1,173,382 $1,175,567 $77.55 $126.38 $17,578 4.2% 2020 $1,928,110 $1,751,462 $898,007 $625,415 $72.30 $106.61 $3,866 4.2% | | |
| Company Selected Measure Name | Growth in Fully Diluted Book Value per Share(5) | | |
| Named Executive Officers, Footnote [Text Block] | Mr. Burton was our PEO for each 2022, 2021, and 2020. For 2020, the non-PEO NEOs were Laura Accurso, Tim Courtis and Messrs. Curnock, Greenspan and O’Brien. For 2021, the non-PEO NEOs were Ms. Accurso, and Messrs. Curnock, Greenspan, and O’Brien. For 2022, the non-PEO NEOs were Messrs. Curnock, Greenspan, Romer, and O’Brien. | | |
| Peer Group Issuers, Footnote [Text Block] | Our Peer Group is the S&P Property and Casualty Insurance Index, which is included in the performance graph in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022.5)The Company has identified Growth in Fully Diluted Book Value per Share as the company-selected measure for the pay-versus-performance disclosure, as it represents the most important financial performance measure used to link compensation actually paid to the CEO and Other NEOs in 2022 to the Company's performance. Fully Diluted Book Value per Share is a non-GAAP measure. Please refer to Annex 1 for definition of non-GAAP measures. | | |
| PEO Total Compensation Amount | $ 2,610,610 | $ 3,114,210 | $ 1,928,110 |
| PEO Actually Paid Compensation Amount | $ 2,916,755 | 2,974,247 | 1,751,462 |
| Adjustment To PEO Compensation, Footnote [Text Block] | The dollar amounts reported represent the amount of CAP to the applicable NEO, as computed in accordance with Item 402(v) of Regulation S-K. The dollar amounts do not reflect the actual amount of compensation earned by or paid during the applicable year. In accordance with the requirements of Item 402(v) of Regulation S-K, the following adjustments were made total compensation, as reported in the Summary Compensation Table, for each year to determine the compensation actually paid: Year Executive(s) Summary Compensation Table Total($) Subtract Stock Awards($) Add Year-End Fair Value of Equity Awards Granted in the Year that are Outstanding and Unvested ($) Add Amount Equal to Change as of the End of Fiscal Year from End of Prior Fiscal Year in Fair Value of Awards Granted in any Prior Fiscal Year that are Outstanding and Unvested Equity Awards($ Add Amount Equal to Change as of the Vesting Date from the End of Prior Fiscal Year in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year($) Subtract Fair Value as of the End of the Prior Year of any Equity Awards Granted in a Prior Year that Failed to Meet Vesting Conditions in the Year($) Total Equity Award Adjustments ($) CAP($) 2022 PEO 2,610,610 (1,600,000) 1,912,023 6,123 (12,000) — 306,145 2,916,755 Other NEOs 841,738 (322,702) 385,634 18,349 (10,752) — 70,528 912,266 2021 PEO 3,114,210 (1,200,000) 1,024,837 (9,600) 44,800 — (139,963) 2,974,247 Other NEOs 1,173,382 (270,000) 230,586 26,759 14,839 — 2,185 1,175,567 2020 PEO 1,928,110 (487,500) — (112,800) 423,652 — (176,649) 1,751,462 Other NEOs 898,007 (230,000) 202,874 (52,176) — 193,291 (272,592) 625,415 | | |
| Non-PEO NEO Average Total Compensation Amount | $ 841,738 | 1,173,382 | 898,007 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 912,266 | 1,175,567 | 625,415 |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | The dollar amounts reported represent the amount of CAP to the applicable NEO, as computed in accordance with Item 402(v) of Regulation S-K. The dollar amounts do not reflect the actual amount of compensation earned by or paid during the applicable year. In accordance with the requirements of Item 402(v) of Regulation S-K, the following adjustments were made total compensation, as reported in the Summary Compensation Table, for each year to determine the compensation actually paid: Year Executive(s) Summary Compensation Table Total($) Subtract Stock Awards($) Add Year-End Fair Value of Equity Awards Granted in the Year that are Outstanding and Unvested ($) Add Amount Equal to Change as of the End of Fiscal Year from End of Prior Fiscal Year in Fair Value of Awards Granted in any Prior Fiscal Year that are Outstanding and Unvested Equity Awards($ Add Amount Equal to Change as of the Vesting Date from the End of Prior Fiscal Year in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year($) Subtract Fair Value as of the End of the Prior Year of any Equity Awards Granted in a Prior Year that Failed to Meet Vesting Conditions in the Year($) Total Equity Award Adjustments ($) CAP($) 2022 PEO 2,610,610 (1,600,000) 1,912,023 6,123 (12,000) — 306,145 2,916,755 Other NEOs 841,738 (322,702) 385,634 18,349 (10,752) — 70,528 912,266 2021 PEO 3,114,210 (1,200,000) 1,024,837 (9,600) 44,800 — (139,963) 2,974,247 Other NEOs 1,173,382 (270,000) 230,586 26,759 14,839 — 2,185 1,175,567 2020 PEO 1,928,110 (487,500) — (112,800) 423,652 — (176,649) 1,751,462 Other NEOs 898,007 (230,000) 202,874 (52,176) — 193,291 (272,592) 625,415 | | |
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | The charts below show, for the past three years, the relationship of TSR relative to the Peer Group TSR, as well as the relationships between PEO and non-PEO NEO average CAP and (i) TSR and (ii) net income. | | |
| Compensation Actually Paid vs. Net Income [Text Block] | | | |
| Tabular List [Table Text Block] | Most Important Performance Measures • Growth in Fully Diluted Book Value Per Share • Underwriting Combined Ratio • Adjusted Operating Profit Growth in Fully Diluted Book Value Per Share. Our primary financial goal is to increase fully diluted book value per share over the long term. We use growth in fully diluted book value per share as performance condition in our long-term incentive compensation. We believe that long-term growth in fully diluted book value per share is the most relevant measure of our financial performance because it provides management and investors a yardstick to monitor the shareholder value generated. Fully diluted book value per share may also help our investors, shareholders, and other interested parties form a basis of comparison with other companies within the property and casualty reinsurance industry. Fully diluted book value per share represents basic book value per share combined with any dilutive impact of in-the-money stock options, unvested service-based RSUs, and the earned portion of unvested performance-based RSUs granted. Fully diluted book value per share also includes the dilutive effect, if any, of ordinary shares expected to be issued upon settlement of our convertible notes. Fully diluted book value per share is a non-GAAP financial measure. Please refer to Annex 1 for definitions of non-GAAP financial measures and reconciliations of GAAP to non-GAAP financial measures. Underwriting Combined Ratio. We evaluate our underwriting performance based on the underwriting combined ratio. We use achievement of underwriting combined ratio as a performance condition in our long-term incentive compensation. Underwriting combined ratio is calculated as 1 minus (the net underwriting income (loss) divided by the net earned premium). We do not use premiums written as a measure of performance. We use net underwriting income (loss) as a performance measure to evaluate the fundamentals underlying the Company’s underwriting operations. We believe that the use of net underwriting income (loss) enables investors and other users of the Company’s financial information to analyze our performance in a manner similar to how management analyzes performance. We believes this measure follows industry practice and allows the users of financial information to compare the Company’s performance with that of our industry peer group. We calculate net underwriting income (loss) as net premiums earned, plus other income relating to reinsurance and deposit-accounted contracts, less deposit interest expense, less net loss and loss adjustment expenses, acquisition costs, and underwriting expenses. Net underwriting income (loss) is a non-GAAP measure. Please refer to Annex 1 for definitions of non-GAAP financial measures and reconciliations of GAAP to non-GAAP financial measures. Adjusted Operating Profit. We also measure our performance based on adjusted operating profit, or AOP, as this measure reflects management’s contribution to long term profitability and operational efficiency. AOP is calculated as the sum of (i) the underwriting income and (ii) the strategic investments income (net of tax), less (iii) corporate innovations-related expense, as a percentage of book value. We use AOP as a performance measure in our short-term incentive compensation. AOP is a non-GAAP performance measure. Please refer to Annex 1 for definitions of non-GAAP financial measures and reconciliations of GAAP to non-GAAP financial measures. | | |
| Total Shareholder Return Amount | $ 80.61 | 77.55 | 72.3 |
| Peer Group Total Shareholder Return Amount | 150.34 | 126.38 | 106.61 |
| Net Income (Loss) | $ 25,342,000 | $ 17,578,000 | $ 3,866,000 |
| Company Selected Measure Amount | 4.3 | 4.2 | 4.2 |
| PEO Name | Mr. Burton | | |
| PEO [Member] | Stock Awards [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | $ 1,600,000 | $ 1,200,000 | $ 487,500 |
| PEO [Member] | Equity Awards Granted in the Year that are Outstanding and Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 1,912,023 | 1,024,837 | 0 |
| PEO [Member] | Equity Awards Granted in any Prior Fiscal Year that are Outstanding and Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 6,123 | 9,600 | 112,800 |
| PEO [Member] | Equity Awards Granted in Prior Years that Vested in the Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 12,000 | 44,800 | 423,652 |
| PEO [Member] | Equity Awards Granted in a Prior Year that Failed to Meet Vesting Conditions in the Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 0 | 0 | 0 |
| PEO [Member] | Equity Award Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 306,145 | 139,963 | 176,649 |
| Non-PEO NEO [Member] | Stock Awards [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 322,702 | 270,000 | 230,000 |
| Non-PEO NEO [Member] | Equity Awards Granted in the Year that are Outstanding and Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 385,634 | 230,586 | 202,874 |
| Non-PEO NEO [Member] | Equity Awards Granted in any Prior Fiscal Year that are Outstanding and Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 18,349 | 26,759 | 52,176 |
| Non-PEO NEO [Member] | Equity Awards Granted in Prior Years that Vested in the Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 10,752 | 14,839 | 0 |
| Non-PEO NEO [Member] | Equity Awards Granted in a Prior Year that Failed to Meet Vesting Conditions in the Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 0 | 0 | 193,291 |
| Non-PEO NEO [Member] | Equity Award Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ 70,528 | $ 2,185 | $ 272,592 |
