Description of Business and Summary of Significant Accounting Policies, Allowance for Credit Losses on Loans (Details)	12 Months Ended
Dec. 31, 2023
Description of Business and Summary of Significant Accounting Policies [Abstract]
Term of reasonable and supportable economic forecast period	1 year
Term of straight line reversion period	1 year

Reasonable and supportable economic forecast period, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

No definition available.

Name:	opof_TermOfReasonableAndSupportableEconomicForecastPeriod
Namespace Prefix:	opof_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration