v3.26.1

Cover - USD ($)	12 Months Ended
Cover - USD ($)	Dec. 31, 2025	Mar. 11, 2026	Jun. 30, 2025
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2025
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2025
Current Fiscal Year End Date	--12-31
Entity File Number	0-16540
Entity Registrant Name	UNITED BANCORP, INC.
Entity Central Index Key	0000731653
Entity Tax Identification Number	34-1405357
Entity Incorporation, State or Country Code	OH
Entity Address, Address Line One	201 South Fourth Street
Entity Address, City or Town	Martins Ferry
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	43935
City Area Code	(740)
Local Phone Number	633-0445
Title of 12(b) Security	Common Stock, Par Value $1.00
Trading Symbol	UBCP
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 66,087,390
Entity Common Stock, Shares Outstanding		5,756,852
Documents Incorporated by Reference [Text Block]	Portions of the proxy statement for the Annual Shareholders meeting to be held April 22, 2026 are incorporated by reference into Part III. Portions of the Annual Report to Shareholders for the year ended December 31, 2025 are incorporated by reference into Parts I and II.
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Auditor Name	S. R. Snodgrass, P.C.
Auditor Location	Cranberry, PA
Auditor Firm ID	74

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Indicate number of shares or other units outstanding of each of registrant's classes of capital or common stock or other ownership interests, if and as stated on cover of related periodic report. Where multiple classes or units exist define each class/interest by adding class of stock items such as Common Class A [Member], Common Class B [Member] or Partnership Interest [Member] onto the Instrument [Domain] of the Entity Listings, Instrument.

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Indicate 'Yes' or 'No' whether registrants (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that registrants were required to file such reports), and (2) have been subject to such filing requirements for the past 90 days. This information should be based on the registrant's current or most recent filing containing the related disclosure.

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Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

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Boolean flag that is true when the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

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The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

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Indicate 'Yes' or 'No' if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Is used on Form Type: 10-K, 10-Q, 8-K, 20-F, 6-K, 10-K/A, 10-Q/A, 20-F/A, 6-K/A, N-CSR, N-Q, N-1A.

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Local phone number for entity.

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UNITED BANCORP INC /OH/ 10-K/A