SEGMENT INFORMATION - Segment income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
INTEREST INCOME
Total interest income	$ 3,779	$ 3,414	$ 10,811	$ 9,889
INTEREST EXPENSE
Total interest expense	1,553	1,325	4,226	3,935
Net interest income	2,226	2,089	6,585	5,954
Provision for credit losses available-for-sale securities
Provision for credit losses loans receivable	80		701	15
Net interest income after provision for credit losses	2,146	2,089	5,884	5,939
NONINTEREST INCOME
Gain on sale of fixed assets				6
Earnings on bank-owned life insurance	26	4	78	26
Net gains on sale of residential mortgage loans	63	51	128	73
Total noninterest income	595	531	1,612	1,406
NONINTEREST EXPENSE
Compensation and employee benefits	1,365	1,227	4,038	3,622
Core processing	435	390	1,146	1,120
Premises and equipment	217	187	662	568
Professional fees	102	56	265	187
Postage & office supplies	23	31	81	87
FDIC premiums	38	30	105	90
Advertising	74	87	257	267
Director fees	38	36	123	124
Other	225	204	649	576
Total noninterest expense	2,517	2,248	7,326	6,641
Income before provision for income taxes	224	372	170	704
PROVISION FOR INCOME TAXES	39	44	33	94
Net income	185	328	137	610
Service fees
NONINTEREST INCOME
Non-interest income	33	30	98	91
Income from financial services
NONINTEREST INCOME
Non-interest income	245	244	709	667
Fee income
NONINTEREST INCOME
Non-interest income	254	206	599	543
Operating Segments | Seneca Savings
INTEREST INCOME
Total interest income	3,779	3,414	10,811	9,889
INTEREST EXPENSE
Total interest expense	1,553	1,325	4,226	3,935
Net interest income	2,226	2,089	6,585	5,954
Provision for credit losses loans receivable	80		701	15
Net interest income after provision for credit losses	2,146	2,089	5,884	5,939
NONINTEREST INCOME
Gain on sale of fixed assets				6
Earnings on bank-owned life insurance			78	26
Net gains on sale of residential mortgage loans	63	51	128	73
Total noninterest income	342	279	879	715
NONINTEREST EXPENSE
Compensation and employee benefits	1,248	1,116	3,686	3,304
Core processing	435	390	1,146	1,120
Premises and equipment	211	181	644	550
Professional fees	77	56	240	187
Postage & office supplies	23	30	80	86
FDIC premiums	38	30	105	90
Advertising	72	86	251	261
Director fees	38	36	122	121
Other	173	151	496	425
Total noninterest expense	2,315	2,076	6,770	6,144
Income before provision for income taxes	173	292	(7)	510
PROVISION FOR INCOME TAXES	39	44	33	94
Net income	134	248	(40)	416
Operating Segments | Seneca Savings | Service fees
NONINTEREST INCOME
Non-interest income	33	30	98	91
Operating Segments | Seneca Savings | Fee income
NONINTEREST INCOME
Non-interest income	246	198	575	519
Operating Segments | Financial Quest
NONINTEREST INCOME
Total noninterest income	253	252	733	691
NONINTEREST EXPENSE
Compensation and employee benefits	117	111	352	318
Premises and equipment	6	6	18	18
Professional fees	25		25
Postage & office supplies		1	1	1
Advertising	2	1	6	6
Director fees			1	3
Other	52	53	153	151
Total noninterest expense	202	172	556	497
Income before provision for income taxes	51	80	177	194
Net income	51	80	177	194
Operating Segments | Financial Quest | Income from financial services
NONINTEREST INCOME
Non-interest income	245	244	709	667
Operating Segments | Financial Quest | Fee income
NONINTEREST INCOME
Non-interest income	$ 8	$ 8	$ 24	$ 24