| Cover | Jul. 20, 2021 | Aug. 10, 2020 |
| Cover [Abstract] | ||
| Document Type | 8-K | |
| Document Period End Date | Jul. 20, 2021 | |
| Entity Registrant Name | ORRSTOWN FINANCIAL SERVICES, INC. | |
| Entity Incorporation, State or Country Code | PA | |
| Entity File Number | 001-34292 | |
| Entity Tax Identification Number | 23-2530374 | |
| Entity Address, Address Line One | 77 East King Street, | |
| Entity Address, Address Line Two | P. O. Box 250 | |
| Entity Address, City or Town | Shippensburg, | |
| Entity Address, State or Province | PA | |
| Entity Address, Postal Zip Code | 17257 | |
| City Area Code | (717) | |
| Local Phone Number | 532-6114 | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Entity Emerging Growth Company | false | |
| Title of 12(b) Security | Common Stock, no par value | |
| Trading Symbol | ORRF | |
| Security Exchange Name | NASDAQ | |
| Entity Central Index Key | 0000826154 | |
| Amendment Flag | false |
