Schedule of Debt Securities Available for Sale with Gross Unrealized Losses, by Investment Category (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Impairment Effects on Earnings Per Share [Line Items]
Available for Sale, Securities Position Over 12 Months, Gross unrealized Losses	$ (7,091)	$ (7,748)
Available for Sale, Securities Position Over 12 Months, Fair Value	24,232	24,569
Available for Sale, Securities Position Less than 12 Month, Gross unrealized Losses	(15)	(39)
Available for Sale, Securities Position Less than 12 Month, Fair Value	123	373
Available for Sale, Securities Position Over 12 Months, Gross unrealized Losses	7,091	7,748
Available for Sale, Securities Position Less than 12 Month, Gross unrealized Losses	15	39
Taxable Municipal Bonds [Member]
Impairment Effects on Earnings Per Share [Line Items]
Available for Sale, Securities Position Over 12 Months, Gross unrealized Losses	(4,480)	(5,109)
Available for Sale, Securities Position Over 12 Months, Fair Value	12,210	11,620
Available for Sale, Securities Position Less than 12 Month, Gross unrealized Losses
Available for Sale, Securities Position Less than 12 Month, Fair Value
Available for Sale, Securities Position Over 12 Months, Gross unrealized Losses	4,480	5,109
Available for Sale, Securities Position Less than 12 Month, Gross unrealized Losses
SBA Pool Securities [Member]
Impairment Effects on Earnings Per Share [Line Items]
Available for Sale, Securities Position Over 12 Months, Gross unrealized Losses	(16)	(18)
Available for Sale, Securities Position Over 12 Months, Fair Value	690	657
Available for Sale, Securities Position Less than 12 Month, Gross unrealized Losses
Available for Sale, Securities Position Less than 12 Month, Fair Value
Available for Sale, Securities Position Over 12 Months, Gross unrealized Losses	16	18
Available for Sale, Securities Position Less than 12 Month, Gross unrealized Losses
Collateralized Mortgage Obligations [Member]
Impairment Effects on Earnings Per Share [Line Items]
Available for Sale, Securities Position Over 12 Months, Gross unrealized Losses
Available for Sale, Securities Position Over 12 Months, Fair Value
Available for Sale, Securities Position Less than 12 Month, Gross unrealized Losses	(15)	(15)
Available for Sale, Securities Position Less than 12 Month, Fair Value	123	130
Available for Sale, Securities Position Over 12 Months, Gross unrealized Losses
Available for Sale, Securities Position Less than 12 Month, Gross unrealized Losses	15	15
Collateralized Mortgage-Backed Securities [Member]
Impairment Effects on Earnings Per Share [Line Items]
Available for Sale, Securities Position Over 12 Months, Gross unrealized Losses	(2,595)	(2,621)
Available for Sale, Securities Position Over 12 Months, Fair Value	11,332	12,292
Available for Sale, Securities Position Less than 12 Month, Gross unrealized Losses		(24)
Available for Sale, Securities Position Less than 12 Month, Fair Value		243
Available for Sale, Securities Position Over 12 Months, Gross unrealized Losses	2,595	2,621
Available for Sale, Securities Position Less than 12 Month, Gross unrealized Losses		$ 24

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 320
-Name Accounting Standards Codification
-Section 50
-Paragraph 3A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480832/942-320-50-3A

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 320
-Name Accounting Standards Codification
-Section 50
-Paragraph 3A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480832/942-320-50-3A

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479106/326-30-50-5

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_TaxableMunicipalBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=OPHC_SBAPoolSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: