ALLOWANCE FOR CREDIT LOSSES - Aging of the Recorded Investment in Loans by Past Due Category and Class of Loan (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	$ 4,071,879	$ 3,852,432
Commercial
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	2,705,713	2,514,917
Commercial & Industrial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	646,742	570,638
Financing Receivable Recorded Investment	648,914	572,966
Farmland \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	125,856	129,934
Financing Receivable Recorded Investment	128,983	132,986
Non Farm, Non Residential \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	910,336	810,392
Financing Receivable Recorded Investment	913,197	812,871
Agriculture \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	138,798	146,054
Financing Receivable Recorded Investment	141,818	149,289
All Other Commercial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	553,612	539,333
Financing Receivable Recorded Investment	557,053	542,397
First Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	448,389	450,232
Financing Receivable Recorded Investment	449,913	451,681
Home Equity \| Residential
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	106,787	89,498
Financing Receivable Recorded Investment	107,118	89,839
Junior Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	72,553	64,712
Financing Receivable Recorded Investment	72,784	64,901
Multifamily \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	330,369	318,566
Multifamily \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	331,837	319,711
All Other Residential \| Residential
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	28,857	44,378
Financing Receivable Recorded Investment	28,986	44,610
Motor Vehicle \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	659,666	636,572
Financing Receivable Recorded Investment	662,657	639,538
All Other Consumer \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Loans receivable	28,469	31,486
Financing Receivable Recorded Investment	28,619	31,643
30-59 Days Past Due
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	15,007	20,844
30-59 Days Past Due \| Commercial & Industrial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	883	746
30-59 Days Past Due \| Farmland \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	320	598
30-59 Days Past Due \| Non Farm, Non Residential \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	1,060	1,619
30-59 Days Past Due \| Agriculture \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	63	0
30-59 Days Past Due \| All Other Commercial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	17	1,297
30-59 Days Past Due \| First Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	3,852	4,304
30-59 Days Past Due \| Home Equity \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	618	639
30-59 Days Past Due \| Junior Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	403	356
30-59 Days Past Due \| Multifamily \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	187	529
30-59 Days Past Due \| All Other Residential \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	26	25
30-59 Days Past Due \| Motor Vehicle \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	7,186	10,176
30-59 Days Past Due \| All Other Consumer \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	392	555
60-89 Days Past Due
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	9,116	4,170
60-89 Days Past Due \| Commercial & Industrial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	3,937	768
60-89 Days Past Due \| Farmland \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	0	0
60-89 Days Past Due \| Non Farm, Non Residential \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	1,772	0
60-89 Days Past Due \| Agriculture \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	71	0
60-89 Days Past Due \| All Other Commercial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	0	152
60-89 Days Past Due \| First Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	1,151	1,361
60-89 Days Past Due \| Home Equity \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	234	157
60-89 Days Past Due \| Junior Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	126	101
60-89 Days Past Due \| Multifamily \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	265	74
60-89 Days Past Due \| All Other Residential \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	0	0
60-89 Days Past Due \| Motor Vehicle \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	1,457	1,435
60-89 Days Past Due \| All Other Consumer \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	103	122
90 Days and Greater Past Due
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	4,643	5,460
90 Days and Greater Past Due \| Commercial & Industrial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	1,640	208
90 Days and Greater Past Due \| Farmland \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	0	806
90 Days and Greater Past Due \| Non Farm, Non Residential \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	85	0
90 Days and Greater Past Due \| Agriculture \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	343	642
90 Days and Greater Past Due \| All Other Commercial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	175	0
90 Days and Greater Past Due \| First Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	779	1,224
90 Days and Greater Past Due \| Home Equity \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	566	906
90 Days and Greater Past Due \| Junior Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	266	290
90 Days and Greater Past Due \| Multifamily \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	68	345
90 Days and Greater Past Due \| All Other Residential \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	24	108
90 Days and Greater Past Due \| Motor Vehicle \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	629	808
90 Days and Greater Past Due \| All Other Consumer \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	68	123
Total Past Due
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	28,766	30,474
Total Past Due \| Commercial & Industrial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	6,460	1,722
Total Past Due \| Farmland \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	320	1,404
Total Past Due \| Non Farm, Non Residential \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	2,917	1,619
Total Past Due \| Agriculture \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	477	642
Total Past Due \| All Other Commercial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	192	1,449
Total Past Due \| First Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	5,782	6,889
Total Past Due \| Home Equity \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	1,418	1,702
Total Past Due \| Junior Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	795	747
Total Past Due \| Multifamily \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	520	948
Total Past Due \| All Other Residential \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	50	133
Total Past Due \| Motor Vehicle \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	9,272	12,419
Total Past Due \| All Other Consumer \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	563	800
Current
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	4,043,113	3,821,958
Current \| Commercial & Industrial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	642,454	571,244
Current \| Farmland \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	128,663	131,582
Current \| Non Farm, Non Residential \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	910,280	811,252
Current \| Agriculture \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	141,341	148,647
Current \| All Other Commercial \| Commercial
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	556,861	540,948
Current \| First Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	444,131	444,792
Current \| Home Equity \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	105,700	88,137
Current \| Junior Liens \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	71,989	64,154
Current \| Multifamily \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	331,317	318,763
Current \| All Other Residential \| Residential
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	28,936	44,477
Current \| Motor Vehicle \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	653,385	627,119
Current \| All Other Consumer \| Consumer
Aging of recorded investment in loans by past due category and class of loans
Financing Receivable Recorded Investment	$ 28,056	$ 30,843

FIRST FINANCIAL CORP /IN/ 10-K