Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2022
Accounting Policies [Abstract]
Nature of Operations and Principles of Consolidation	Nature of Operations and Principles of Consolidation: The consolidated financial statements of Cullman Bancorp, Inc. (“the Bancorp”) include the accounts of its wholly owned subsidiary, Cullman Savings Bank (“the Bank”), together referred to as “the Company”. The Company provides financial services through its offices in Cullman County, Alabama. Its primary deposit products are checking, savings, and term certificate accounts, and its primary lending products are residential mortgage, commercial, and installment loans. Substantially all loans are secured by specific items of collateral including business assets, consumer assets, and commercial and residential real estate. Commercial loans are expected to be repaid from cash flow from operations of businesses. There are no significant concentrations of loans to any one industry or customer. However, the customers' ability to repay their loans is dependent on the real estate and general economic conditions in the area. Effective July 15, 2021, the Bancorp became the stock holding company for the Bank as part of the mutual-to-stock conversion of Cullman Savings Bank, MHC. As a result of the conversion, Cullman Savings Bank, MHC and Cullman Bancorp, Inc. a federal corporation (Cullman Federal) ceased to exist and the Bancorp became the successor corporation to Cullman Federal. In the conversion, 3,929,776 shares of common stock were sold at a price of $10.00 per share is the subscription offering, which included 354,599 shares sold to the Employee Stock Ownership Plan. The Bancorp additionally issued 148,210 shares to The Cullman Foundation, a charitable foundation that was formed in connection with the stock offering and is dedicated to supporting charitable organizations operating in the Bank's local community. The exchange ratio for previously held shares of Cullman Federal was 2.8409 as applied in the conversion offering. Share amounts related to the periods prior to the conversion have been restated to give retroactive recognition to the exchange ratio.
Risk and Uncertainties	Risk and Uncertainties: On March 11, 2020, the World Health Organization declared COVID-19, the disease caused by the novel coronavirus, a pandemic as a result of the global spread of the coronavirus illness. The outlook has continued to improve in regards to COVID-19; however, there are concerns such as supply chain and labor shortages that continue to persist. There continues to be uncertainty regarding the long term effect of the global economy which could have an adverse impact on the Company's business operations.
Recent Accounting Pronouncements and Accounting Changes	As an “emerging growth company” under the Jumpstart Our Business Startups Act of 2012 (“JOBS Act”), the Company is permitted an extended transition period for complying with new or revised accounting standards affecting public companies. We will remain an emerging growth company until the earliest of (i) the end of the fiscal year during which we have total annual gross revenues of $1.07 billion or more, (ii) the end of the fiscal year following the fifth anniversary of the completion of our initial public offering (December 31, 2026), (iii) the date on which we have, during the previous three year period, issued more than $1.0 billion in non-convertible debt and (iv) the end of the fiscal year in which the market value of our equity securities that are held by non-affiliates exceeds $700 million as of June 30 of that year. We have elected to take advantage of this extended transition period, which means that the financial statements included herein, as well as any financial statements that we file in the future, will not be subject to all new or revised accounting standards generally applicable to public companies for the transition period for so long as we remain an emerging growth company or until we affirmatively and irrevocably opt out of the extended transition period under the JOBS Act. If we do so, we will prominently disclose this decision in the first periodic report following our decision, and such decision is irrevocable. As a filer under the JOBS Act, we will implement new accounting standards subject to the effective dates required for non-public entities. FASB ASU 2016-13 (Topic 326), “Measurement of Credit Losses on Financial Instruments” Issued in June 2016, Accounting Standards Update (ASU) 2016-13 significantly changes how companies measure and recognize credit impairment for many financial assets. This ASU requires businesses and other organizations to measure the current expected credit losses (“CECL”) on financial assets, such as loans, net investments in leases, certain debt securities, bond insurance and other receivables. The amendments affect entities holding financial assets and net investments in leases that are not accounted for at fair value through net income. Current GAAP requires an incurred loss methodology for recognizing credit losses that delays recognition until it is probable a loss has been incurred. The amendments in this ASU replace the incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonableness and supportable information to inform credit loss estimates. An entity should apply the amendments through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective (modified retrospective approach). Acquired credit impaired loans for which the guidance in Accounting Standards Codification (ASC) Topic 310-30 has been previously applied should prospectively apply the guidance in this ASU. NOTE 1 - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Continued) A prospective transition approach is required for debt securities for which an other-than-temporary impairment has been recognized before the effective date. In October 2019, the FASB approved a delay for the implementation of the ASU. Accordingly, as an emerging growth company, the Corporation’s effective date for the implementation of the ASU will be January 1, 2023. Key project implementation activities for 2022 and 2021 have focused on execution and implementation, processes and control, policies, disclosures, and data resolution. At this time the Corporation cannot yet estimate the impact to the consolidated financial statements.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2022

Nature of Operations and Principles of Consolidation

Nature of Operations and Principles of Consolidation: The consolidated financial statements of Cullman Bancorp, Inc. (“the Bancorp”) include the accounts of its wholly owned subsidiary, Cullman Savings Bank (“the Bank”), together referred to as “the Company”.

The Company provides financial services through its offices in Cullman County, Alabama. Its primary deposit products are checking, savings, and term certificate accounts, and its primary lending products are residential mortgage, commercial, and installment loans. Substantially all loans are secured by specific items of collateral including business assets, consumer assets, and commercial and residential real estate. Commercial loans are expected to be repaid from cash flow from operations of businesses. There are no significant concentrations of loans to any one industry or customer. However, the customers' ability to repay their loans is dependent on the real estate and general economic conditions in the area.

Effective July 15, 2021, the Bancorp became the stock holding company for the Bank as part of the mutual-to-stock conversion of Cullman Savings Bank, MHC. As a result of the conversion, Cullman Savings Bank, MHC and Cullman Bancorp, Inc. a federal corporation (Cullman Federal) ceased to exist and the Bancorp became the successor corporation to Cullman Federal. In the conversion, 3,929,776 shares of common stock were sold at a price of $10.00 per share is the subscription offering, which included 354,599 shares sold to the Employee Stock Ownership Plan. The Bancorp additionally issued 148,210 shares to The Cullman Foundation, a charitable foundation that was formed in connection with the stock offering and is dedicated to supporting charitable organizations operating in the Bank's local community. The exchange ratio for previously held shares of Cullman Federal was 2.8409 as applied in the conversion offering. Share amounts related to the periods prior to the conversion have been restated to give retroactive recognition to the exchange ratio.

Risk and Uncertainties

Risk and Uncertainties: On March 11, 2020, the World Health Organization declared COVID-19, the disease caused by the novel coronavirus, a pandemic as a result of the global spread of the coronavirus illness. The outlook has continued to improve in regards to COVID-19; however, there are concerns such as supply chain and labor shortages that continue to persist. There continues to be uncertainty regarding the long term effect of the global economy which could have an adverse impact on the Company's business operations.

Recent Accounting Pronouncements and Accounting Changes

As an “emerging growth company” under the Jumpstart Our Business Startups Act of 2012 (“JOBS Act”), the Company is permitted an extended transition period for complying with new or revised accounting standards affecting public companies. We will remain an emerging growth company until the earliest of (i) the end of the fiscal year during which we have total annual gross revenues of $1.07 billion or more, (ii) the end of the fiscal year following the fifth anniversary of the completion of our initial public offering (December 31, 2026), (iii) the date on which we have, during the previous three year period, issued more than $1.0 billion in non-convertible debt and (iv) the end of the fiscal year in which the market value of our equity securities that are held by non-affiliates exceeds $700 million as of June 30 of that year. We have elected to take advantage of this extended transition period, which means that the financial statements included herein, as well as any financial statements that we file in the future, will not be subject to all new or revised accounting standards generally applicable to public companies for the transition period for so long as we remain an emerging growth company or until we affirmatively and irrevocably opt out of the extended transition period under the JOBS Act. If we do so, we will prominently disclose this decision in the first periodic report following our decision, and such decision is irrevocable. As a filer under the JOBS Act, we will implement new accounting standards subject to the effective dates required for non-public entities.

FASB ASU 2016-13 (Topic 326), “Measurement of Credit Losses on Financial Instruments”

Issued in June 2016, Accounting Standards Update (ASU) 2016-13 significantly changes how companies measure and recognize credit impairment for many financial assets. This ASU requires businesses and other organizations to measure the current expected credit losses (“CECL”) on financial assets, such as loans, net investments in leases, certain debt securities, bond insurance and other receivables. The amendments affect entities holding financial assets and net investments in leases that are not accounted for at fair value through net income. Current GAAP requires an incurred loss methodology for recognizing credit losses that delays recognition until it is probable a loss has been incurred. The amendments in this ASU replace the incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonableness and supportable information to inform credit loss estimates. An entity should apply the amendments through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective (modified retrospective approach). Acquired credit impaired loans for which the guidance in Accounting Standards Codification (ASC) Topic 310-30 has been previously applied should prospectively apply the guidance in this ASU.

NOTE 1 - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Continued)

A prospective transition approach is required for debt securities for which an other-than-temporary impairment has been recognized before the effective date. In October 2019, the FASB approved a delay for the implementation of the ASU. Accordingly, as an emerging growth company, the Corporation’s effective date for the implementation of the ASU will be January 1, 2023. Key project implementation activities for 2022 and 2021 have focused on execution and implementation, processes and control, policies, disclosures, and data resolution. At this time the Corporation cannot yet estimate the impact to the consolidated financial statements.