| Pay vs Performance Disclosure | 3 Months Ended | 10 Months Ended | 12 Months Ended | 14 Months Ended |
| Oct. 31, 2022 | Oct. 31, 2022 | Dec. 31, 2023 USD ($) $ / shares | Dec. 31, 2022 USD ($) $ / shares | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2023 |
| Pay vs Performance Disclosure | | | | | | | |
| Pay vs Performance Disclosure, Table | | | Value of Initial Fixed $100 Invested Based On: Year Summary Compen- sation Table Total for PEO - Charles N. Funk (1) Summary Compen-sation Table Total for PEO - Charles N. Reeves (2) Summary Compen-sation Table Total for PEO - Len D. Devaisher (3) Compen-sation Actually Paid to PEO - Charles N. Funk (1) Compen-sation Actually Paid to PEO - Charles N. Reeves (2) Compen-sation Actually Paid to PEO - Len D. Devaisher (3) Avg. Summary Compen-sation Table Total for Non-PEO NEOs (4) Avg. Compen-sation Actually Paid to Non-PEO NEOs (4) Company TSR Peer Group TSR (5) Net Income in millions CSM 2023 $ — $ 1,463,067 $ — $ — $ 1,286,192 $ — $ 567,529 $ 440,616 $ 85.8 $ 100.1 $ 20.9 $ 1.33 2022 1,034,428 424,261 981,987 1,033,562 399,968 985,874 538,102 537,760 96.9 98.0 60.8 3.87 2021 1,156,260 — — 1,435,821 — — 583,656 695,448 95.8 113.6 69.5 4.37 2020 951,134 — — 682,861 — — 464,897 377,901 70.4 86.0 6.6 0.41 | | | | |
| Company Selected Measure Name | | | Diluted Earnings Per Share | | | | |
| Named Executive Officers, Footnote | | | Mr. Funk served as our PEO for the period 2020 through 2022. Mr. Funk stepped down as Chief Executive Officer of the Company, effective November 1, 2022, and served as a Special Advisor to the CEO until April 27, 2023, at which time he retired from employment with the Company. (2) Mr. Reeves was appointed Chief Executive Officer of the Company, effective November 1, 2022. (3) Mr. Devaisher served as the interim Chief Executive Officer in addition to President & Chief Operating Officer while Mr. Funk was recuperating from August 12, 2022 until November 1, 2022. (4) The Other NEOs represent the following individuals for years 2023, 2021, and 2020: Messrs. Devaisher, Ray, Sims and Lindstrom and for the year 2022: Messrs. Ray, Sims and Lindstrom. | | | | |
| Peer Group Issuers, Footnote | | | The peer group index is the S&P U.S. BMI Banks - Midwest Region, which is included in Item 5, “Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities,” found on page 27, of the Company’s Form 10-K for the year ended December 31, 2023 . | | | | |
| Adjustment To PEO Compensation, Footnote | | | PEO - Mr. Funk SCT Total to CAP Reconciliation (3) Year SCT-PEO Change in Fair Value of Equity Awards Granted in the Year (1) Change in Fair Value of Outstanding Unvested Equity Awards Granted in Prior Years (1) Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year Value of Dividends or Other Earnings Paid on Equity Awards (2) CAP 2022 $ 1,034,428 $ 3,537 $ 1,499 $ — $ (5,244) $ — $ (658) $ 1,033,562 2021 1,156,260 53,478 202,594 — 15,824 — 7,665 1,435,821 2020 951,134 (155,215) (87,975) — (19,600) — (5,483) 682,861 (1) The change in the fair value of the equity awards granted in 2020 reflects that the Company would not achieve a threshold level of performance over the three-year performance measurement period for the PSU awards. In 2021, the fair value of the 2020 awards was restored based upon the projected level of performance determined at that time, which is reflected in the change in fair value of the outstanding unvested equity awards granted in the prior year. (2) Includes the cumulative change in the fair value of dividend equivalents that were granted, vested, and outstanding. Such dividend equivalent units are subject to the same vesting, payment and other terms and conditions as the underlying RSUs and PSUs to which they relate. (3) Mr. Funk served as our PEO for the period 2020 through 2022. Mr. Funk stepped down as Chief Executive Officer of the Company, effective November 1, 2022, and served as a Special Advisor to the CEO until April 27, 2023, at which time he retired from employment with the Company. PEO - Mr. Reeves SCT Total to CAP Reconciliation (1) Year SCT-PEO Change in Fair Value of Equity Awards Granted in the Year Change in Fair Value of Outstanding Unvested Equity Awards Granted in Prior Years Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year Value of Dividends or Other Earnings Paid on Equity Awards CAP 2023 $ 1,463,067 $ (127,324) $ (22,956) $ — $ (22,742) $ — $ (3,853) $ 1,286,192 2022 424,261 (24,118) — — — — (175) 399,968 (1) Mr. Reeves was appointed Chief Executive Officer of the Company, effective November 1, 2022. PEO - Mr. Devaisher SCT Total to CAP Reconciliation (1) Year SCT-PEO Change in Fair Value of Equity Awards Granted in the Year Change in Fair Value of Outstanding Unvested Equity Awards Granted in Prior Years Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year Value of Dividends or Other Earnings Paid on Equity Awards CAP 2022 $ 981,987 $ 1,887 $ 2,665 $ — $ (359) $ — $ (306) $ 985,874 | | | | |
| Non-PEO NEO Average Total Compensation Amount | | | $ 567,529 | $ 538,102 | $ 583,656 | $ 464,897 | |
| Non-PEO NEO Average Compensation Actually Paid Amount | | | $ 440,616 | 537,760 | 695,448 | 377,901 | |
| Adjustment to Non-PEO NEO Compensation Footnote | | | Average Non-PEO NEOs SCT Total to CAP Reconciliation Year SCT-NEO Change in Fair Value of Equity Awards Granted in the Year (1) Change in Fair Value of Outstanding Unvested Equity Awards Granted in Prior Years (1) Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year Value of Dividends or Other Earnings Paid on Equity Awards (2) CAP 2023 $ 567,529 $ (57,786) $ (53,399) $ — $ (11,339) $ — $ (4,389) $ 440,616 2022 538,102 1,277 185 — (1,597) — (207) 537,760 2021 583,656 21,658 81,366 — 5,774 — 2,994 695,448 2020 464,897 (47,790) (21,994) — (16,370) — (842) 377,901 (1) The change in the fair value of the equity awards granted in 2020 reflects that the Company would not achieve a threshold level of performance over the three-year performance measurement period for the PSU awards. In 2021, the fair value of the 2020 awards was restored based upon the projected level of performance determined at that time, which is reflected in the change in fair value of the outstanding unvested equity awards granted in the prior year. | | | | |
| Compensation Actually Paid vs. Total Shareholder Return | | | As shown in the chart below, the PEOs’ CAP and Other NEOs’ average CAP amounts are directionally aligned with the Company’s TSR. This is due primarily to the Company’s use of equity incentives, the value of which moves in line with our TSR, in addition to the Company’s financial performance. | | | | |
| Compensation Actually Paid vs. Net Income | | | As shown in the chart below, the PEOs’ CAP and Other NEOs’ average CAP amounts are directionally aligned with changes in the Company’s net income. This is due in large part to the significant emphasis the Company places on equity incentives, the value of which are affected by our TSR. The Company does not use net income to determine compensation levels or incentive plan payouts. | | | | |
| Compensation Actually Paid vs. Company Selected Measure | | | As shown in the chart below, the PEOs’ CAP and Other NEOs’ average CAP amounts are directionally aligned with changes in the Company’s diluted earnings per share. | | | | |
| Total Shareholder Return Vs Peer Group | | | The following chart presents the cumulative total shareholder return, assuming reinvestment of dividends, over the four-year period for the Company and the S&P U.S. BMI Banks - Midwest Region Index (S&P Bank Index). As the table demonstrates, the Company’s four-year cumulative TSR is below our peer group index. | | | | |
| Tabular List, Table | | | The table below lists the most important financial metrics used to link 2023 CAP to Company performance. Diluted earnings per share, return on average tangible equity and the efficiency ratio are further described in our Compensation Discussion and Analysis (“CD&A”) within the sections titled “Annual Cash Incentive Awards” and “Long-Term Incentive Awards (Equity Awards).” Most Important Performance Measures Diluted Earnings Per Share Return on Average Tangible Equity Efficiency Ratio | | | | |
| Total Shareholder Return Amount | | | $ 85.8 | 96.9 | 95.8 | 70.4 | |
| Peer Group Total Shareholder Return Amount | | | 100.1 | 98 | 113.6 | 86 | |
| Net Income (Loss) | | | $ 20,900,000 | $ 60,800,000 | $ 69,500,000 | $ 6,600,000 | |
| Company Selected Measure Amount | | | 1.33 | 3.87 | 4.37 | 0.41 | |
| PEO Name | Mr. Devaisher | Mr. Funk | | | Mr. Funk | Mr. Funk | Mr. Reeves |
| Measure:: 1 | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Name | | | Diluted Earnings Per Share | | | | |
| Measure:: 2 | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Name | | | Return on Average Tangible Equity | | | | |
| Measure:: 3 | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Name | | | Efficiency Ratio | | | | |
| Charles Funk [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| PEO Total Compensation Amount | | | $ 0 | $ 1,034,428 | $ 1,156,260 | $ 951,134 | |
| PEO Actually Paid Compensation Amount | | | 0 | 1,033,562 | 1,435,821 | 682,861 | |
| Charles Reeves [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| PEO Total Compensation Amount | | | 1,463,067 | 424,261 | | | |
| PEO Actually Paid Compensation Amount | | | 1,286,192 | 399,968 | | | |
| Len D Devaisher [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| PEO Total Compensation Amount | | | 0 | 981,987 | | | |
| PEO Actually Paid Compensation Amount | | | 0 | 985,874 | | | |
| PEO | Charles Funk [Member] | Change in Fair Value of Equity Awards Granted in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | 3,537 | 53,478 | (155,215) | |
| PEO | Charles Funk [Member] | Change in Fair Value of Outstanding Unvested Equity Awards Granted in Prior Years [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | 1,499 | 202,594 | (87,975) | |
| PEO | Charles Funk [Member] | Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | 0 | 0 | 0 | |
| PEO | Charles Funk [Member] | Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | (5,244) | 15,824 | (19,600) | |
| PEO | Charles Funk [Member] | Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | 0 | 0 | 0 | |
| PEO | Charles Funk [Member] | Value of Dividends or Other Earnings Paid on Equity Awards [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | (658) | 7,665 | (5,483) | |
| PEO | Charles Reeves [Member] | Change in Fair Value of Equity Awards Granted in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | (127,324) | (24,118) | | | |
| PEO | Charles Reeves [Member] | Change in Fair Value of Outstanding Unvested Equity Awards Granted in Prior Years [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | (22,956) | 0 | | | |
| PEO | Charles Reeves [Member] | Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | 0 | 0 | | | |
| PEO | Charles Reeves [Member] | Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | (22,742) | 0 | | | |
| PEO | Charles Reeves [Member] | Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | 0 | 0 | | | |
| PEO | Charles Reeves [Member] | Value of Dividends or Other Earnings Paid on Equity Awards [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | (3,853) | (175) | | | |
| PEO | Len D Devaisher [Member] | Change in Fair Value of Equity Awards Granted in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | 1,887 | | | |
| PEO | Len D Devaisher [Member] | Change in Fair Value of Outstanding Unvested Equity Awards Granted in Prior Years [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | 2,665 | | | |
| PEO | Len D Devaisher [Member] | Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | 0 | | | |
| PEO | Len D Devaisher [Member] | Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | (359) | | | |
| PEO | Len D Devaisher [Member] | Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | 0 | | | |
| PEO | Len D Devaisher [Member] | Value of Dividends or Other Earnings Paid on Equity Awards [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | | (306) | | | |
| Non-PEO NEO | Change in Fair Value of Equity Awards Granted in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | (57,786) | 1,277 | 21,658 | (47,790) | |
| Non-PEO NEO | Change in Fair Value of Outstanding Unvested Equity Awards Granted in Prior Years [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | (53,399) | 185 | 81,366 | (21,994) | |
| Non-PEO NEO | Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | 0 | 0 | 0 | 0 | |
| Non-PEO NEO | Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | (11,339) | (1,597) | 5,774 | (16,370) | |
| Non-PEO NEO | Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | 0 | 0 | 0 | 0 | |
| Non-PEO NEO | Value of Dividends or Other Earnings Paid on Equity Awards [Member] | | | | | | | |
| Pay vs Performance Disclosure | | | | | | | |
| Adjustment to Compensation, Amount | | | $ (4,389) | $ (207) | $ 2,994 | $ (842) | |
