| Pay vs Performance Disclosure | 3 Months Ended | 9 Months Ended | 12 Months Ended |
| Mar. 31, 2021 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) |
| Pay vs Performance Disclosure | | | | | | |
| Pay vs Performance Disclosure, Table | | | Pay Versus Performance As required by Section 953(a) of the Dodd-Frank Wall Street Reform and Consumer Protection Act and Item 402(v) of Regulation S-K, we are providing the following information about the relationship between executive compensation actually paid (as defined by SEC rules) and certain financial performance measures of the Company. The Compensation Committee did not consider the pay versus performance disclosure when making its incentive compensation decisions. The following tables set forth information regarding compensation for our principal executive officers (PEOs) and average compensation related to our Non-PEO NEOs versus our Company performance for 2023, 2022, 2021, and 2020. Year Douglas D. Dirks (PEO) (1) Katherine H. Antonello (PEO) (1) Non-PEO NEOs (2) Summary Compensation Table Total for PEO ($) (1) Compensation Actually Paid to PEO ($) (3) Summary Compensation Table Total for PEO ($) (1) Compensation Actually Paid to PEO ($) (3) Average Summary Compensation Table Total for Non-PEO NEOs ($) (2,3) Average Compensation Actually Paid to Non-PEO NEOs ($) (2,3) 2023 $ — $ — $ 3,727,106 $ 3,498,957 $ 1,290,919 $ 1,012,519 2022 $ — $ — $ 2,518,681 $ 2,649,349 $ 1,078,779 $ 1,139,759 2021 $ 2,315,871 $ 2,373,415 $ 2,570,729 $ 2,971,888 $ 1,183,048 $ 1,402,493 2020 $ 3,662,640 $ 2,091,105 $ — $ — $ 1,440,715 $ 974,288 Value of Initial Fixed $100 Investment Based on: Company Selected Measure (5) Year Total Shareholder Return (4) Peer Group Total Shareholder Return (4) Net Income Adjusted GAAP Calendar Year 2023 $ 110.83 $ 168.05 $ 118.1 94.7 % 2022 $ 118.02 $ 151.65 $ 48.4 97.0 % 2021 $ 104.79 $ 127.58 $ 119.3 97.6 % 2020 $ 79.46 $ 106.96 $ 119.8 95.4 % (1) The dollar amounts reported in this column reflect the total compensation presented in the 2023 Summary Compensation Table for each fiscal year shown. Mr. Dirks served as our President and CEO (PEO) for all of 2020 and in 2021 until he retired on April 1, 2021. Effective April 1, 2021, Ms. Antonello was promoted to President and CEO. She served as our PEO for the remainder of 2021 and throughout 2022 and 2023. (2) The dollar amounts reported in this column reflect the average amounts of total compensation reported for our Non-PEO NEOs presented in the 2023 Summary Compensation Table for each fiscal year shown. During 2023, our Non-PEO NEOs consisted of Messrs. Paquette, Mutschink, and Shaw and Ms. Brown. During 2022 and 2021, our Non-PEO NEOs consisted of Mr. Paquette, Christopher Laws, Mr. Shaw and Ms. Brown. During 2020, our Non-PEO NEOs consisted of Mr. Paquette, Stephen Festa, Tracey Berg and Ms. Antonello. (3) The amounts calculated in these columns are in accordance with Item 402(v) of Regulation S-K. See the table below for detail of amounts added to and deducted from the total compensation presented in the 2023 Summary Compensation Table for each applicable fiscal year to calculate compensation actually paid. Note that there were no stock awards granted in any fiscal year that vested within such fiscal year. 2023 2022 PEO($) Average of Non-PEO NEOs($) PEO($) Average of Non-PEO NEOs($) Total Compensation reported on Summary Compensation Table 3,727,106 1,290,919 2,518,681 1,078,779 (Less) Fair Value of stock awards reported on Summary Compensation Table (1,699,905) (419,422) (594,057) (249,053) Fair Value of stock awards granted in fiscal year shown, valued at year-end, that were outstanding and unvested at end of fiscal year shown 1,628,008 316,941 632,010 264,965 Change in fair value from end of prior fiscal year to end of fiscal year shown for awards previously granted that were outstanding and unvested at end of fiscal year shown (115,817) (34,446) 70,648 33,126 Change in fair value from end of prior fiscal year to vesting date for awards previously granted in prior fiscal years that vested during fiscal year shown (40,435) (6,659) 22,067 11,942 (Less) Fair Value as of prior fiscal year for any awards granted in any prior fiscal year that fail to meet applicable vesting conditions during the covered fiscal year — (134,814) — — Compensation Actually Paid 3,498,957 1,012,519 2,649,349 1,139,759 2021 2020 PEO - PEO - Antonello($) Average of Non-PEO NEOs($) PEO($) Average of Non-PEO NEOs($) Total Compensation reported on Summary Compensation Table 2,315,871 2,570,729 1,183,048 3,662,640 1,440,715 (Less) Fair Value of stock awards reported on Summary Compensation Table (1,184,664) (922,733) (428,545) (1,848,909) (615,414) Fair Value of stock awards granted in fiscal year shown, valued at year-end, that were outstanding and unvested at end of fiscal year shown — 1,017,120 469,622 1,574,091 508,039 Change in fair value from end of prior fiscal year to end of fiscal year shown for awards previously granted that were outstanding and unvested at end of fiscal year shown — 161,193 106,363 (695,315) (219,737) Change in fair value from end of prior fiscal year to vesting date for awards previously granted in prior fiscal years that vested during fiscal year shown 1,242,208 145,579 72,005 (601,402) (139,315) Compensation Actually Paid 2,373,415 2,971,888 1,402,493 2,091,105 974,288 (4) Total Shareholder Return assumes an initial fixed investment of $100 as of December 31, 2019, which was established by the market close on the last trading day prior to the beginning of the Company's fourth preceding fiscal year. Total shareholder return also includes reinvestment of all dividends. The Peer Group Total Shareholder Return is based on the Standard & Poor's 500 Property & Casualty Insurance Index as identified in the Stock Performance Graph included in our Annual Reports on Form 10-K for fiscal years 2023, 2022, 2021, and 2020. (5) The Company has determined that the most important financial performance measure, or Company Selected Measure, the Company used to align pay and performance by linking compensation actually paid to our NEOs for fiscal year 2023 was the Adjusted GAAP Calendar Year Combined Ratio. Adjusted GAAP Calendar Year Combined Ratio = (Losses + loss adjustment expenses + commission expense - amortization of the deferred gain +/- impact of the LPT reserve adjustment +/- impact of the loss portfolio transfer contingent commission adjustment) / net premiums earned plus (underwriting expenses + general and administrative expenses) / net premiums written. | | | |
| Company Selected Measure Name | | | Adjusted GAAP Calendar Year Combined Ratio | | | |
| Named Executive Officers, Footnote | | | The dollar amounts reported in this column reflect the average amounts of total compensation reported for our Non-PEO NEOs presented in the 2023 Summary Compensation Table for each fiscal year shown. During 2023, our Non-PEO NEOs consisted of Messrs. Paquette, Mutschink, and Shaw and Ms. Brown. During 2022 and 2021, our Non-PEO NEOs consisted of Mr. Paquette, Christopher Laws, Mr. Shaw and Ms. Brown. During 2020, our Non-PEO NEOs consisted of Mr. Paquette, Stephen Festa, Tracey Berg and Ms. Antonello. | | | |
| Peer Group Issuers, Footnote | | | The Peer Group Total Shareholder Return is based on the Standard & Poor's 500 Property & Casualty Insurance Index as identified in the Stock Performance Graph included in our Annual Reports on Form 10-K for fiscal years 2023, 2022, 2021, and 2020. | | | |
| Adjustment To PEO Compensation, Footnote | | | The amounts calculated in these columns are in accordance with Item 402(v) of Regulation S-K. See the table below for detail of amounts added to and deducted from the total compensation presented in the 2023 Summary Compensation Table for each applicable fiscal year to calculate compensation actually paid. Note that there were no stock awards granted in any fiscal year that vested within such fiscal year. 2023 2022 PEO($) Average of Non-PEO NEOs($) PEO($) Average of Non-PEO NEOs($) Total Compensation reported on Summary Compensation Table 3,727,106 1,290,919 2,518,681 1,078,779 (Less) Fair Value of stock awards reported on Summary Compensation Table (1,699,905) (419,422) (594,057) (249,053) Fair Value of stock awards granted in fiscal year shown, valued at year-end, that were outstanding and unvested at end of fiscal year shown 1,628,008 316,941 632,010 264,965 Change in fair value from end of prior fiscal year to end of fiscal year shown for awards previously granted that were outstanding and unvested at end of fiscal year shown (115,817) (34,446) 70,648 33,126 Change in fair value from end of prior fiscal year to vesting date for awards previously granted in prior fiscal years that vested during fiscal year shown (40,435) (6,659) 22,067 11,942 (Less) Fair Value as of prior fiscal year for any awards granted in any prior fiscal year that fail to meet applicable vesting conditions during the covered fiscal year — (134,814) — — Compensation Actually Paid 3,498,957 1,012,519 2,649,349 1,139,759 2021 2020 PEO - PEO - Antonello($) Average of Non-PEO NEOs($) PEO($) Average of Non-PEO NEOs($) Total Compensation reported on Summary Compensation Table 2,315,871 2,570,729 1,183,048 3,662,640 1,440,715 (Less) Fair Value of stock awards reported on Summary Compensation Table (1,184,664) (922,733) (428,545) (1,848,909) (615,414) Fair Value of stock awards granted in fiscal year shown, valued at year-end, that were outstanding and unvested at end of fiscal year shown — 1,017,120 469,622 1,574,091 508,039 Change in fair value from end of prior fiscal year to end of fiscal year shown for awards previously granted that were outstanding and unvested at end of fiscal year shown — 161,193 106,363 (695,315) (219,737) Change in fair value from end of prior fiscal year to vesting date for awards previously granted in prior fiscal years that vested during fiscal year shown 1,242,208 145,579 72,005 (601,402) (139,315) Compensation Actually Paid 2,373,415 2,971,888 1,402,493 2,091,105 974,288 | | | |
| Non-PEO NEO Average Total Compensation Amount | | | $ 1,290,919 | $ 1,078,779 | $ 1,183,048 | $ 1,440,715 |
| Non-PEO NEO Average Compensation Actually Paid Amount | | | $ 1,012,519 | 1,139,759 | 1,402,493 | 974,288 |
| Adjustment to Non-PEO NEO Compensation Footnote | | | The amounts calculated in these columns are in accordance with Item 402(v) of Regulation S-K. See the table below for detail of amounts added to and deducted from the total compensation presented in the 2023 Summary Compensation Table for each applicable fiscal year to calculate compensation actually paid. Note that there were no stock awards granted in any fiscal year that vested within such fiscal year. 2023 2022 PEO($) Average of Non-PEO NEOs($) PEO($) Average of Non-PEO NEOs($) Total Compensation reported on Summary Compensation Table 3,727,106 1,290,919 2,518,681 1,078,779 (Less) Fair Value of stock awards reported on Summary Compensation Table (1,699,905) (419,422) (594,057) (249,053) Fair Value of stock awards granted in fiscal year shown, valued at year-end, that were outstanding and unvested at end of fiscal year shown 1,628,008 316,941 632,010 264,965 Change in fair value from end of prior fiscal year to end of fiscal year shown for awards previously granted that were outstanding and unvested at end of fiscal year shown (115,817) (34,446) 70,648 33,126 Change in fair value from end of prior fiscal year to vesting date for awards previously granted in prior fiscal years that vested during fiscal year shown (40,435) (6,659) 22,067 11,942 (Less) Fair Value as of prior fiscal year for any awards granted in any prior fiscal year that fail to meet applicable vesting conditions during the covered fiscal year — (134,814) — — Compensation Actually Paid 3,498,957 1,012,519 2,649,349 1,139,759 2021 2020 PEO - PEO - Antonello($) Average of Non-PEO NEOs($) PEO($) Average of Non-PEO NEOs($) Total Compensation reported on Summary Compensation Table 2,315,871 2,570,729 1,183,048 3,662,640 1,440,715 (Less) Fair Value of stock awards reported on Summary Compensation Table (1,184,664) (922,733) (428,545) (1,848,909) (615,414) Fair Value of stock awards granted in fiscal year shown, valued at year-end, that were outstanding and unvested at end of fiscal year shown — 1,017,120 469,622 1,574,091 508,039 Change in fair value from end of prior fiscal year to end of fiscal year shown for awards previously granted that were outstanding and unvested at end of fiscal year shown — 161,193 106,363 (695,315) (219,737) Change in fair value from end of prior fiscal year to vesting date for awards previously granted in prior fiscal years that vested during fiscal year shown 1,242,208 145,579 72,005 (601,402) (139,315) Compensation Actually Paid 2,373,415 2,971,888 1,402,493 2,091,105 974,288 | | | |
| Compensation Actually Paid vs. Total Shareholder Return | | | The following graphical comparisons illustrate the relationships between certain amounts included in the Pay Versus Performance table for fiscal years 2023, 2022, 2021, and 2020, including: (i) a comparison of Compensation Actually Paid Versus Cumulative Total Shareholder Return; (ii) a comparison of Compensation Actually Paid Versus Net Income; and (iii) a comparison of Compensation Actually Paid Versus Adjusted GAAP Calendar Year Combined Ratio. | | | |
| Compensation Actually Paid vs. Net Income | | | | | | |
| Compensation Actually Paid vs. Company Selected Measure | | | | | | |
| Tabular List, Table | | | As described in the above "Compensation Discussion and Analysis," the Company's executive compensation program uses financial performance measures used in our industry and measures that are viewed as key financial drivers of our stock price to align pay and performance. The most important financial performance measures used to link executive compensation actually paid with the Company's performance include the following: Most Important Financial Performance Measures for Fiscal Year 2023 ◦ Adjusted GAAP Calendar Year Combined Ratio ◦ Change in Adjusted Book Value Per Share (ABVPS) | | | |
| Total Shareholder Return Amount | | | $ 110.83 | 118.02 | 104.79 | 79.46 |
| Peer Group Total Shareholder Return Amount | | | 168.05 | 151.65 | 127.58 | 106.96 |
| Net Income (Loss) | | | $ 118,100,000 | $ 48,400,000 | $ 119,300,000 | $ 119,800,000 |
| Company Selected Measure Amount | | | 0.947 | 0.970 | 0.976 | 0.954 |
| PEO Name | | | Ms. Antonello | | | Mr. Dirks |
| Measure:: 1 | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Name | | | ◦Adjusted GAAP Calendar Year Combined Ratio | | | |
| Measure:: 2 | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Name | | | ◦Change in Adjusted Book Value Per Share (ABVPS) | | | |
| Douglas Dirks, CEO [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| PEO Total Compensation Amount | $ 2,315,871 | | $ 0 | $ 0 | | $ 3,662,640 |
| PEO Actually Paid Compensation Amount | 2,373,415 | | 0 | 0 | | 2,091,105 |
| Katherine Antonello, CEO [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| PEO Total Compensation Amount | | $ 2,570,729 | 3,727,106 | 2,518,681 | | 0 |
| PEO Actually Paid Compensation Amount | | 2,971,888 | 3,498,957 | 2,649,349 | | 0 |
| PEO | Douglas Dirks, CEO [Member] | FV of Stock Awards Reported in Summary Comp Table [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | (1,184,664) | | | | | (1,848,909) |
| PEO | Douglas Dirks, CEO [Member] | FV of Stock Awards Granted in CY valued at YE [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | 0 | | | | | 1,574,091 |
| PEO | Douglas Dirks, CEO [Member] | Change in FV from End of Prior FY to end of Current FY for Awards Granted Prior that were Outstanding and Unvested at Current FY [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | 0 | | | | | (695,315) |
| PEO | Douglas Dirks, CEO [Member] | Change in FV from End of Prior FY to Vesting Date for Awards Granted in Prior FY that Vested during Current FY [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | $ 1,242,208 | | | | | (601,402) |
| PEO | Katherine Antonello, CEO [Member] | FV of Stock Awards Reported in Summary Comp Table [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | | (922,733) | (1,699,905) | (594,057) | | |
| PEO | Katherine Antonello, CEO [Member] | FV of Stock Awards Granted in CY valued at YE [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | | 1,017,120 | 1,628,008 | 632,010 | | |
| PEO | Katherine Antonello, CEO [Member] | Change in FV from End of Prior FY to end of Current FY for Awards Granted Prior that were Outstanding and Unvested at Current FY [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | | 161,193 | (115,817) | 70,648 | | |
| PEO | Katherine Antonello, CEO [Member] | Change in FV from End of Prior FY to Vesting Date for Awards Granted in Prior FY that Vested during Current FY [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | | $ 145,579 | (40,435) | 22,067 | | |
| PEO | Katherine Antonello, CEO [Member] | FV as of End of Prior FY for Awards Granted in Prior FY that Forfeited during Current FY [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | | | 0 | 0 | | |
| Non-PEO NEO | FV of Stock Awards Reported in Summary Comp Table [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | | | (419,422) | (249,053) | $ (428,545) | (615,414) |
| Non-PEO NEO | FV of Stock Awards Granted in CY valued at YE [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | | | 316,941 | 264,965 | 469,622 | 508,039 |
| Non-PEO NEO | Change in FV from End of Prior FY to end of Current FY for Awards Granted Prior that were Outstanding and Unvested at Current FY [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | | | (34,446) | 33,126 | 106,363 | (219,737) |
| Non-PEO NEO | Change in FV from End of Prior FY to Vesting Date for Awards Granted in Prior FY that Vested during Current FY [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | | | (6,659) | 11,942 | $ 72,005 | $ (139,315) |
| Non-PEO NEO | FV as of End of Prior FY for Awards Granted in Prior FY that Forfeited during Current FY [Member] | | | | | | |
| Pay vs Performance Disclosure | | | | | | |
| Adjustment to Compensation, Amount | | | $ (134,814) | $ 0 | | |
