| Cover | Aug. 10, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Apr. 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 |
