Loans and Allowance for Loan Losses - Schedule of Troubled Debt Restructurings on Financing Receivables (Details) $ in Thousands	3 Months Ended
Mar. 31, 2021 USD ($) contract	Mar. 31, 2020 USD ($) contract
Commercial loans
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	1	2
Pre- Modification Outstanding Recorded Investment	$ 86	$ 83
Post-Modification Outstanding Recorded Investment	67	83
Interest Only	0	0
Term	67	83
Combination	0	0
Total Modification	$ 67	$ 83
Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	0	0
Pre- Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	0	0
Interest Only	0	0
Term	0	0
Combination	0	0
Total Modification	$ 0	$ 0
Residential real estate
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	0	0
Pre- Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	0	0
Interest Only	0	0
Term	0	0
Combination	0	0
Total Modification	$ 0	$ 0
Installment loans
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	0	0
Pre- Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	0	0
Consumer
Financing Receivable, Modifications [Line Items]
Interest Only	0	0
Term	0	0
Combination	0	0
Total Modification	$ 0	$ 0

Financing receivable, modifications combination

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Financing receivable modifications interest only

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Financing receivable, modifications term

+ References

No definition available.

+ Details

Name:	ubcp_FinancingReceivableModificationsTerm
Namespace Prefix:	ubcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The total amount of modifications made to financing receivables.

+ References

No definition available.

+ Details

Name:	ubcp_FinancingReceivableTotalModifications
Namespace Prefix:	ubcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableModificationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, before troubled debt restructuring, of financing receivable to be modified.

+ References

+ Details

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- Details

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- Details

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- Details

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- Details

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