LOANS AND ALLOWANCE FOR LOAN LOSSES - Summary of Average Recorded Investment in Impaired Loans and Related Interest Income (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	$ 7,130	$ 15,118	$ 14,346
Interest Income Recognized	66	33	174
Commercial real estate \| Owner-occupied
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	1,000	1,758	2,613
Interest Income Recognized	6	0	0
Commercial real estate \| Non-owner occupied
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	392	6,831	3,470
Interest Income Recognized	0	0	0
Commercial real estate \| Multi-family
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	182	216	402
Interest Income Recognized	0	0	0
Commercial real estate \| Non-owner occupied residential
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	418	645	1,020
Interest Income Recognized	0	0	0
Acquisition and development \| 1-4 family residential construction
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	154	0	0
Interest Income Recognized	0	0	0
Acquisition and development \| Commercial and land development
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	0	3	266
Interest Income Recognized	0	0	137
Commercial and industrial
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	413	575	1,208
Interest Income Recognized	0	0	0
Residential mortgage \| First lien
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	4,012	4,525	4,644
Interest Income Recognized	58	33	37
Residential mortgage \| Home equity – term
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	61	98	130
Interest Income Recognized	0	0	0
Residential mortgage \| Home equity lines of credit
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	488	455	571
Interest Income Recognized	2	0	0
Installment and other loans
Financing Receivable, Impaired [Line Items]
Average Impaired Balance	10	12	22
Interest Income Recognized	$ 0	$ 0	$ 0

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.

No definition available.

+ Details

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

- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=orrf_OwnerOccupiedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=orrf_NonOwnerOccupiedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_MultifamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=orrf_NonOwnerOccupiedResidentialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=orrf_AcquisitionAndDevelopmentPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=orrf_OneToFourFamilyResidentialConstructionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=orrf_CommercialAndLandDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=orrf_CommercialAndIndustrialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=orrf_FirstLienMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=orrf_HomeEquityTermMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=orrf_InstallmentandOtherLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: