Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2017
Accounting Policies [Abstract]
Nature of Operations [Policy Text Block]	Nature of Operations: Consumers Bancorp, Inc. (the Corporation) is a bank holding company headquartered in Minerva, Ohio that provides, through its banking subsidiary, Consumers National Bank (the Bank), a broad array of products and services throughout its primary market area of Carroll, Columbiana, Jefferson, Stark, Summit, Wayne and contiguous counties in Ohio. The Bank’s business involves attracting deposits from businesses and individual customers and using such deposits to originate commercial, mortgage and consumer loans in its primary market area.
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation : The consolidated financial statements for interim periods are unaudited and reflect all adjustments (consisting of only normal recurring adjustments), which, in the opinion of management, are necessary to present fairly the financial position and results of operations and cash flows for the periods presented. The unaudited financial statements are presented in accordance with the requirements of Form 10 -Q and do not include all disclosures normally required by accounting principles generally accepted in the United States of America. The financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Corporation’s Form 10 -K for the year ended June 30, 2017. The results of operations for the interim period disclosed herein are not necessarily indicative of the results that may be expected for a full year. The consolidated financial statements include the accounts of the Corporation and the Ban k. All significant inter-company transactions and accounts have been eliminated in consolidation.
Segment Reporting, Policy [Policy Text Block]	Segment Information: The Corporation is a bank holding company engaged in the business of commercial and retail banking, which accounts for substantially all of the revenues, operating income, and assets. Accordingly, all of its operations are recorded in one segment, banking.
Reclassification, Policy [Policy Text Block]	Reclassifications: Certain items in prior financial statements have been reclassified to conform to the current presentation. Any reclassifications had no impact on prior year net income or shareholders’ equity.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Pronouncements Not Yet Effective: In May 2014, FASB issued Accounting Standards Update (ASU) 2014 - 09, Revenue from Contracts with Customers (Topic 606 ). The ASU creates a new topic, Topic 606, to provide guidance on revenue recognition for entities that enter into contracts with customers to transfer goods or services or enter into contracts for the transfer of nonfinancial assets. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Additional disclosures are required to provide quantitative and qualitative information regarding the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2017. The adoption of ASU 2014 - 09 as it relates to non-interest income, such as service charges and debit card interchange income, is not expected to have a material effect on the Corporation’s financial statements. In January 2016, the FASB issued ASU 2016 - 01, Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities. The main provisions of ASU 2016 - 01 address the valuation and impairment of certain equity investments along with simplified disclosures about those investments. Equity securities with readily determinable fair values will be treated in the same manner as other financial instruments. ASU 2016 - 01 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The adoption of ASU 2016 - 01 is not expected to have a material impact on the Corporation's financial statements. In June 2016, FASB Is sued ASU 2016 - 13, Financial Instruments—Credit Losses (Topic 326 ): Measurement of Credit Losses on Financial Instruments. This ASU adds a new Topic 326 to the codification and removes the thresholds that companies apply to measure credit losses on financial instruments measured at amortized cost, such as loans, receivables, and held-to-maturity debt securities. Under current U.S. GAAP, companies generally recognize credit losses when it is probable that the loss has been incurred. The revised guidance will remove all current loss recognition thresholds and will require companies to recognize an allowance for credit losses for the difference between the amortized cost basis of a financial instrument and the amount of amortized cost that the corporation expects to collect over the instrument’s contractual life. ASU 2016 - 13 also amends the credit loss measurement guidance for available-for-sale debt securities and beneficial interests in securitized financial assets. The guidance in ASU 2016 - 13 is effective for “public business entities,” as defined, that are SEC filers for fiscal years and for interim periods with those fiscal years beginning after December 15, 2019. Early adoption of the guidance is permitted for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Management is currently evaluating the impact of the adoption of this guidance on the Corporation’s consolidated financial statements, and are in the midst of gathering critical data to evaluate the impact. However, it is too early to estimate the impact. In February 2016, the FASB issued ASU 2016 - 02 - Leases (Topic 842 ). The ASU will require all organizations that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. Additional qualitative and quantitative disclosures will be required so that users can understand more about the nature of an entity’s leasing activities. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted. Management is currently evaluating the impact of the adoption of this guidance on the Corporation’s consolidated financial statements and expects to recognize an increase in other assets and other liabilities for the rights and obligations created by leasing of branch offices. Management also expects minimal impact in the income statement with respect to occupancy expense related to leases.