FAIR VALUE - Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Investment securities:
Investment securities	$ 952,740	$ 829,711
U.S. Treasury securities
Investment securities:
Investment securities	14,211	18,063
U.S. government agencies
Investment securities:
Investment securities	1,796	3,053
States and political subdivisions
Investment securities:
Investment securities	202,148	200,028
GSE residential MBSs
Investment securities:
Investment securities	234,103	151,548
GSE residential CMOs
Investment securities:
Investment securities	354,003	324,692
Non-agency CMOs
Investment securities:
Investment securities	59,823	33,284
Asset-backed
Investment securities:
Investment securities	78,250	88,103
Corporate debt
Investment securities:
Investment securities	1,992	1,954
Other
Investment securities:
Investment securities	243	194
Fair Value, Measurements, Recurring
Investment securities:
Loans held for sale	6,090	6,614
Totals	973,506	849,776
Fair Value, Measurements, Recurring \| Interest rate swaps
Investment securities:
Derivatives	14,676	13,451
Financial Liabilities
Derivatives	15,138	12,575
Fair Value, Measurements, Recurring \| U.S. Treasury securities
Investment securities:
Investment securities	14,211	18,063
Fair Value, Measurements, Recurring \| U.S. government agencies
Investment securities:
Investment securities	1,796	3,053
Fair Value, Measurements, Recurring \| States and political subdivisions
Investment securities:
Investment securities	202,148	200,028
Fair Value, Measurements, Recurring \| GSE residential MBSs
Investment securities:
Investment securities	234,103	151,548
Fair Value, Measurements, Recurring \| GSE Commercial MBSs
Investment securities:
Investment securities	6,171	8,792
Fair Value, Measurements, Recurring \| GSE residential CMOs
Investment securities:
Investment securities	354,003	324,692
Fair Value, Measurements, Recurring \| Non-agency CMOs
Investment securities:
Investment securities	59,823	33,284
Fair Value, Measurements, Recurring \| Asset-backed
Investment securities:
Investment securities	78,250	88,103
Fair Value, Measurements, Recurring \| Corporate debt
Investment securities:
Investment securities	1,992	1,954
Fair Value, Measurements, Recurring \| Other
Investment securities:
Investment securities	243	194
Fair Value, Measurements, Recurring \| Level 1
Investment securities:
Loans held for sale	0	0
Totals	14,454	18,257
Fair Value, Measurements, Recurring \| Level 1 \| Interest rate swaps
Investment securities:
Derivatives	0	0
Financial Liabilities
Derivatives	0	0
Fair Value, Measurements, Recurring \| Level 1 \| U.S. Treasury securities
Investment securities:
Investment securities	14,211	18,063
Fair Value, Measurements, Recurring \| Level 1 \| U.S. government agencies
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| States and political subdivisions
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| GSE residential MBSs
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| GSE Commercial MBSs
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| GSE residential CMOs
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Non-agency CMOs
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Asset-backed
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Corporate debt
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Other
Investment securities:
Investment securities	243	194
Fair Value, Measurements, Recurring \| Level 2
Investment securities:
Loans held for sale	6,090	6,614
Totals	943,686	814,579
Fair Value, Measurements, Recurring \| Level 2 \| Interest rate swaps
Investment securities:
Derivatives	14,638	13,431
Financial Liabilities
Derivatives	15,138	12,575
Fair Value, Measurements, Recurring \| Level 2 \| U.S. Treasury securities
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 2 \| U.S. government agencies
Investment securities:
Investment securities	1,796	3,053
Fair Value, Measurements, Recurring \| Level 2 \| States and political subdivisions
Investment securities:
Investment securities	196,482	193,756
Fair Value, Measurements, Recurring \| Level 2 \| GSE residential MBSs
Investment securities:
Investment securities	234,103	151,548
Fair Value, Measurements, Recurring \| Level 2 \| GSE Commercial MBSs
Investment securities:
Investment securities	6,171	8,792
Fair Value, Measurements, Recurring \| Level 2 \| GSE residential CMOs
Investment securities:
Investment securities	354,003	324,692
Fair Value, Measurements, Recurring \| Level 2 \| Non-agency CMOs
Investment securities:
Investment securities	50,161	22,636
Fair Value, Measurements, Recurring \| Level 2 \| Asset-backed
Investment securities:
Investment securities	78,250	88,103
Fair Value, Measurements, Recurring \| Level 2 \| Corporate debt
Investment securities:
Investment securities	1,992	1,954
Fair Value, Measurements, Recurring \| Level 2 \| Other
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 3
Investment securities:
Loans held for sale	0	0
Totals	15,366	16,940
Fair Value, Measurements, Recurring \| Level 3 \| Interest rate swaps
Investment securities:
Derivatives	38	20
Financial Liabilities
Derivatives	0	0
Fair Value, Measurements, Recurring \| Level 3 \| U.S. Treasury securities
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| U.S. government agencies
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| States and political subdivisions
Investment securities:
Investment securities	5,666	6,272
Fair Value, Measurements, Recurring \| Level 3 \| GSE residential MBSs
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| GSE Commercial MBSs
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| GSE residential CMOs
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Non-agency CMOs
Investment securities:
Investment securities	9,662	10,648
Fair Value, Measurements, Recurring \| Level 3 \| Asset-backed
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Corporate debt
Investment securities:
Investment securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Other
Investment securities:
Investment securities	$ 0	$ 0

ORRSTOWN FINANCIAL SERVICES INC 10-K