SHARE-BASED COMPENSATION PLANS - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2025 USD ($) plan shares	Dec. 31, 2024 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-based compensation plans | plan	2
Number of shares reserved to be issued (in shares)	1,045,000
Number of shares available to be issued under employee stock purchase plan (in shares)	665,000
Unrecognized compensation expense, recognition period	1 year 9 months 18 days
Orrstown Financial Services, Inc. 2025 Incentive Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved to be issued (in shares)	440,000
Number of shares available to be issued under employee stock purchase plan (in shares)	370,647
Orrstown 2011 Incentive Stock Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense | $	$ 4.7	$ 3.6
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved to be issued (in shares)	350,000
Number of shares available to be issued under employee stock purchase plan (in shares)	122,980
Maximum shares that can be purchased, as percentage of annual salary	10.00%
Percentage of value of the shares on the semi-annual offering	95.00%