Description of Business and Summary of Significant Accounting Policies, Allowance for Credit Losses on Loans (Details)	3 Months Ended
Mar. 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