Significant Accounting Policies (Policies)	3 Months Ended
Significant Accounting Policies (Policies)	Mar. 31, 2020
Accounting Policies [Abstract]
Consolidation, Policy [Policy Text Block]	Principles of Consolidation and Basis of Presentation The accompanying consolidated financial statements include the accounts of CB Financial Services, Inc. (“CB Financial”) and its wholly owned subsidiary, Community Bank (the “Bank”), and the Bank’s wholly-owned subsidiary, Exchange Underwriters, Inc. (“Exchange Underwriters” or “EU”). CB Financial and the Bank are collectively referred to as the “Company”. All intercompany transactions and balances have been eliminated in consolidation. The accompanying unaudited interim financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) and in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading in any material respect. In preparing financial statements in conformity with GAAP, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and income and expenses during the reporting period. Actual results could differ significantly from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to determination of the allowance for losses on loans, the valuation of real estate acquired in connection with foreclosures or in satisfaction of loans, evaluation of securities for other-than-temporary impairment including related cash flow projections, goodwill and intangible assets impairment, and the valuation of deferred tax assets. In the opinion of management, the accompanying unaudited interim financial statements include all adjustments considered necessary for a fair presentation of the Company’s financial position and results of operations at the dates and for the periods presented. All these adjustments are of a normal, recurring nature, and they are the only adjustments included in the accompanying unaudited interim financial statements. These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto in the Company’s Annual Report on Form 10 -K for the year ended December 31, 2019. Interim results are not necessarily indicative of results for a full year. The Company evaluated subsequent events through the date the consolidated financial statements were filed with the SEC and incorporated into the consolidated financial statements the effect of all material known events determined by Accounting Standards Codification ("ASC”) 855, Subsequent Events , to be recognizable events.
Nature of Operations [Policy Text Block]	Nature of Operations The Company derives substantially all its income from banking and bank-related services which include interest earnings on commercial, commercial mortgage, residential real estate and consumer loan financing, as well as interest earnings on investment securities and fees generated from deposit services to its customers. The Company provides banking services through its subsidiary, Community Bank, a Pennsylvania-chartered commercial bank headquartered in Carmichaels, Pennsylvania. The Bank operates from twenty offices in Greene, Allegheny, Washington, Fayette and Westmoreland Counties in southwestern Pennsylvania, seven offices in Brooke, Marshall, Ohio, Upshur and Wetzel Counties in West Virginia, and one office in Belmont County in Ohio. The Bank is a community-oriented institution offering residential and commercial real estate loans, commercial and industrial loans, and consumer loans as well as a variety of deposit products for individuals and businesses in its market area. Property and casualty, commercial liability, surety and other insurance products are offered through Exchange Underwriters, a full-service, independent insurance agency.
Reclassification, Comparability Adjustment [Policy Text Block]	Reclassifications Certain comparative amounts for the prior year have been reclassified to conform to the current year presentation. Such reclassifications did not affect net income or stockholders’ equity.
Goodwill and Intangible Assets, Policy [Policy Text Block]	Goodwill Goodwill represents the excess of the cost of an acquisition over the fair value of the net assets acquired. At March 31, 2020 and December 31, 2019, the carrying value of goodwill was $28.4 million. Goodwill is subject to impairment testing at the reporting unit level, which is conducted at least annually on October 31 or more frequently if triggering events occur or impairment indicators exist. The Company operates two reporting units – Community Banking segment and Insurance Brokerage Services segment. The Company has assigned 100% of the goodwill to the Community Banking reporting unit. In 2019, the Company adopted Accounting Standards Update (“ASU”) 2017 - 04 whereby the Company applies a one -step quantitative test and records the amount of goodwill impairment as the excess of a reporting unit's carrying amount over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. The Company has the option of performing a qualitative assessment to determine whether any further quantitative testing for impairment is necessary. The option of whether or not to perform a qualitative assessment is made annually. The quantitative test primarily utilizes market comparisons and recent merger and acquisition transactions to determine whether there is goodwill impairment. The COVID- 19 pandemic that has impacted the U.S. and most of the world and government response to curtail the spread of the virus through shelter-in-place orders and mandatory closures of all but essential businesses beginning in March 2020 has significantly impacted our market area and the activities of individuals. These restrictions have resulted in significant adverse effects on macroeconomic conditions, and stock market valuations have decreased substantially for most companies, including banks. The ultimate effect of COVID- 19 on the local or broader economy is not known nor is the ultimate length of the restrictions described and any accompanying effects. In light of the adverse circumstances resulting from COVID- 19, management determined it was necessary to evaluate goodwill for impairment at March 31, 2020. Determining the fair value of a reporting unit under a quantitative goodwill impairment test is judgmental and often involves the use of significant estimates and assumptions. The Company utilized a market approach to determine the fair value of the Community Banking reporting unit. Significant assumptions inherent in the valuation methodologies for goodwill are employed and include, but are not limited to, current and prospective financial information of the Bank, most recent performance of the Bank’s peers, including common banking industry performance measures and ratios, and comparable multiples from publicly traded companies in our industry. The valuation was primarily based on observable price to tangible book value bank merger and acquisition multiples for similar size community banks, which is the most widely used valuation metric in the community banking industry. As part of its analysis, the Company considered bank transactions of target banks that were comparable in asset size, risk and profitability and efficiency metrics during the “Great Recession” period from 2008 to 2010 when bank stock values were depressed and the stock market decline was similar with the current sudden and unexpected events caused by the COVID- 19 pandemic. Based on the analysis, management determined that goodwill was not impaired as of March 31, 2020. Future events, particularly worsening business, profitability and economic conditions as of a result of the COVID- 19 pandemic, could cause additional triggering events and require management to further evaluate goodwill for impairment.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Standards In March 2020, the Financial Accounting Standard Board (“FASB”) issued ASU2020 - 04, Reference Rate Reform (Topic 848 ): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. This ASU provides temporary optional guidance to ease the potential burden in accounting for reference rate reform. The new guidance provides optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference the London Inter-bank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued. The elective guidance in the ASU applies to modifications of contract terms that will directly replace, or have the potential to replace, an affected rate with another interest rate index, as well as certain contemporaneous modifications of other contract terms related to the replacement of an affected rate. The ASU notes that changes in contract terms that are made to effect the reference rate reform transition are considered related to the replacement of a reference rate if they are not the result of a business decision that is separate from or in addition to changes to the terms of a contract to effect that transition. The optional expedient allows companies to account for the modification as if it was not substantial (i.e., do not treat as an extinguishment of debt). The ASU is intended to help stakeholders during the global market-wide reference rate transition period. ASU 2020 - 04 is effective for all entities as of March 12, 2020 through December 31, 2022. While the LIBOR reform may require extensive changes to the contracts that govern LIBOR based products, as well as our systems and processes, we cannot yet determine whether the Company will be able to use the optional expedient for the changes to contract terms that may be required by LIBOR reform and therefore, the Company cannot yet determine the magnitude of the impact or the overall impact of the new guidance on the Company’s consolidated financial condition or results of operation. In August 2018, the FASB issued ASU 2018 - 15 , Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350 - 40 ) . ASU 2018 - 15 was issued to help entities evaluate the accounting for fees paid by a customer in a cloud computing arrangement (hosting arrangement) by providing guidance for determining when the arrangement includes a software license. The amendments align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by the amendments. This guidance became effective for the Company beginning in the first quarter 2020 and the adoption of this ASU did not have a material impact on the Company's consolidated statement of financial condition or results of operations. In August 2018, the FASB issued ASU 2018 - 13, Fair Value Measurement (Topic 820 ) . ASU 2018 - 13 modifies disclosure requirements on fair value measurements. This ASU removes requirements to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, the policy for timing of transfers between levels and the valuation processes for Level 3 fair value measurements. ASU 2018 - 13 clarifies that disclosure regarding measurement uncertainty is intended to communicate information about the uncertainty in measurement as of the reporting date. ASU 2018 - 13 adds certain disclosure requirements, including disclosure of changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The amendments in this ASU were effective for the Company beginning in the first quarter 2020. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively, while all other amendments should be applied retrospectively for all periods presented. The adoption of this ASU did not have a material impact on the Company's consolidated statement of financial condition or results of operations. In January 2017, the FASB issued ASU 2017 - 04, Intangibles - Goodwill and Other (Topic 350 ): Simplifying the Test for Goodwill Impairment . ASU 2017 - 04 simplifies the accounting for goodwill impairments by eliminating the second step of the goodwill impairment test. Instead, an entity applies a one -step quantitative test and records the amount of goodwill impairment as the excess of a reporting unit's carrying amount over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. The new guidance does not amend the optional qualitative assessment of goodwill impairment. ASU 2017 - 04 is effective for public business entities for annual periods beginning after December 15, 2019, and interim periods within those annual periods, with early adoption permitted, and is to be applied on a prospective basis. The Company elected to early adopt the provisions of ASU 2017 - 04 effective October 31, 2019 and the adoption did not have a material impact on the Company's consolidated statement of financial condition or results of operations. In September 2016, the FASB issued ASU 2016 - 13, Financial Instruments – Credit Losses (Topic 326 ): Measurement of Credit Losses on Financial Instruments . ASU 2016 - 13 amends guidance on reporting credit losses for assets held at amortized cost basis and available for sale debt securities. For assets held at amortized cost basis, ASU 2016 - 13 eliminates the probable initial recognition threshold in current GAAP; and instead requires an entity to reflect its current estimate of all expected credit losses. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial assets to present the net amount expected to be collected. For available-for-sale debt securities, credit losses should be measured in a manner similar to current GAAP, however this ASU requires that credit losses be presented as an allowance rather than as a write-down. ASU 2016 - 13 affects companies holding financial assets and net investment in leases that are not accounted for at fair value through net income. The ASU 2016 - 13 amendments affect loans, debt securities, trade receivables, net investments in leases, off balance-sheet credit exposures, reinsurance receivables, and any other financial assets not excluded from the scope that have the contractual right to receive cash. ASU 2016 - 13 was originally effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted. In November 2019, the FASB approved a delay of the required implementation date of ASU 2016 - 13 for smaller reporting companies, including the Company, resulting in a required implementation date for the Company of January 1, 2023. Early adoption will continue to be permitted. The Company is evaluating the impact of this ASU and expects to recognize a one -time adjustment to the allowance for loan losses upon adoption, but we cannot yet determine the magnitude of the one -time adjustment or the overall impact of the new guidance on the Company’s consolidated financial condition or results of operation.