Cover Page
| Cover Page - USD ($) $ in Millions | 12 Months Ended | ||
| Dec. 31, 2021 | Mar. 31, 2022 | Jun. 30, 2021 | |
| Cover [Abstract] | |||
| Document Type | 10-K/A | ||
| Document Period End Date | Dec. 31, 2021 | ||
| Amendment Flag | true | ||
| Document Fiscal Year Focus | 2021 | ||
| Document Fiscal Period Focus | FY | ||
| Trading Symbol | BCOW | ||
| Entity Registrant Name | 1895 Bancorp of Wisconsin, Inc. | ||
| Entity Central Index Key | 0001847360 | ||
| Current Fiscal Year End Date | --12-31 | ||
| Entity Current Reporting Status | Yes | ||
| Entity Shell Company | false | ||
| Entity Filer Category | Non-accelerated Filer | ||
| Entity Small Business | true | ||
| Entity Emerging Growth Company | true | ||
| Entity Ex Transition Period | false | ||
| Entity Address, State or Province | WI | ||
| Entity Interactive Data Current | Yes | ||
| Title of 12(b) Security | Common stock | ||
| Security Exchange Name | NASDAQ | ||
| Entity Common Stock, Shares Outstanding | 6,371,198 | ||
| Entity File Number | 001-40609 | ||
| Entity Tax Identification Number | 61-1993378 | ||
| Entity Address, Address Line One | 7001 West Edgerton Avenue | ||
| Entity Address, City or Town | Greenfield | ||
| Entity Address, Postal Zip Code | 53220 | ||
| City Area Code | 414 | ||
| Local Phone Number | 421-8200 | ||
| Entity Incorporation, State or Country Code | MD | ||
| Document Annual Report | true | ||
| Document Transition Report | false | ||
| Entity Public Float | $ 86.4 | ||
| Entity Well-known Seasoned Issuer | No | ||
| Entity Voluntary Filers | No | ||
| ICFR Auditor Attestation Flag | false | ||
| Amendment Description | This Amendment No. 1 to the Annual Report on Form 10-K (this “Amendment”) amends the Annual Report on Form 10-K for the fiscal year ended December 31, 2021 originally filed with the Securities and Exchange Commission on March 29, 2022 (the “Original Filing”) by 1895 Bancorp of Wisconsin, Inc., a Maryland corporation (“1895 Bancorp” or the “Company”). 1895 Bancorp is filing this Amendment to present the information required by Part III of Form 10-K as the Company will not file its definitive proxy statement within 120 days of the end of its fiscal year ended December 31, 2021. Except as described above, no other changes have been made to the Original Filing. The Original Filing continues to speak as of the date of the Original Filing, and the Company has not updated the disclosures contained therein to reflect any events which occurred at a date subsequent to the filing of the Original Filing. 1895 Bancorp was formed to serve as the stock holding company for PyraMax Bank, FSB (“PyraMax Bank”) as part of the mutual-to-stock conversion of 1895 Bancorp of Wisconsin, MHC (the “MHC”). Upon completion of the conversion, which occurred on July 14, 2021, the MHC and 1895 Bancorp of Wisconsin, Inc., a federal corporation (“Old 1895 Bancorp”), ceased to exist and the Company became the successor corporation to Old 1895 Bancorp. The conversion was accomplished by the merger of the MHC with and into Old 1895 Bancorp, followed by the merger of Old 1895 Bancorp with and into the Company. On July 14, 2021, public stockholders of Old 1895 Bancorp received 1.3163 shares of the Company’s common stock in exchange for each of their shares of Old 1895 Bancorp. Prior to the completion of the conversion on July 14, 2021, the Company had no assets or liabilities and had not conducted any business activities other than organizational activities. Accordingly, the information contained in this Amendment relate to the MHC, Old 1895 Bancorp and PyraMax Bank for any period prior to July 14, 2021, and relate to the Company and PyraMax Bank for periods after July 14, 2021. | ||
| Documents Incorporated by Reference | DOCUMENTS INCORPORATED BY REFERENCE: None. | ||
| Auditor Name | Wipfli LLP | ||
| Auditor Firm ID | 344 | ||
| Auditor Location | Eau Claire, Wisconsin |