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RETIREMENT AND POSTRETIREMENT PLANS (Tables) | 12 Months Ended
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Dec. 31, 2024
Other Postretirement Benefits Plan [Member] |
Defined Benefit Plan Disclosure |
Schedule of funded status of defined benefit plan | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year Ended December 31,
(In thousands) |  | 2024 |  | 2023
Reconciliation of projected benefit obligation: | ​ |  |  | ​ |  |
Projected benefit obligation at beginning of year | ​ | $ | 18,721 | ​ | $ | 19,021
Interest cost | ​ |  | 847 | ​ |  | 900
Actuarial (gain) loss | ​ |  | (1,101) | ​ |  | 384
Benefit payments | ​ |  | (1,649) | ​ |  | (1,584)
Projected benefit obligation at end of year | ​ |  | 16,818 | ​ |  | 18,721
​ | ​ |  |  | ​ |  |
Plan assets at fair value (investments in trust funds managed by trustee) | ​ |  |  | ​ |  |
Balance at beginning of year | ​ |  | 21,303 | ​ |  | 22,593
Return on plan assets | ​ |  | (448) | ​ |  | 294
Benefit payments | ​ |  | (1,649) | ​ |  | (1,584)
Balance at end of year | ​ |  | 19,206 | ​ |  | 21,303
Funded status at end of year | ​ | $ | 2,388 | ​ | $ | 2,582
Schedule of components of net periodic (credit) benefit cost included in other non-interest expense | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year Ended December 31,
(In thousands) | ​ | 2024 |  | 2023 |  | 2022
Interest cost | ​ | $ | 847 | ​ | $ | 900 | ​ | $ | 622
Expected return on plan assets | ​ |  | (1,429) | ​ |  | (1,521) | ​ |  | (1,949)
Amortization of unrealized loss | ​ |  | 854 | ​ |  | 572 | ​ |  | 261
Net periodic benefit (credit) cost | ​ | $ | 272 | ​ | $ | (49) | ​ | $ | (1,066)
Schedule of change in accumulated other comprehensive loss | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year Ended December 31,
(In thousands) |  | 2024 |  | 2023
Balance at beginning of period | ​ | $ | (6,363) | ​ | $ | (5,323)
Amortization of unrealized loss | ​ |  | 854 | ​ |  | 572
Loss recognized during the year | ​ |  | (776) | ​ |  | (1,612)
Balance at the end of the period | ​ | $ | (6,285) | ​ | $ | (6,363)
Period end component of accumulated other comprehensive loss, net of tax | ​ | $ | 4,356 | ​ | $ | 4,343
Schedule of major assumptions utilized to determine the net periodic cost of Plan benefit obligations | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | At or for the Year Ended December 31, | ​
​ |  | 2024 | ​ | ​ | 2023 | ​ | ​ | 2022 | ​
Discount rate used for net periodic benefit cost |  | 4.70 | % | ​ | 4.90 | % | ​ | 2.55 | %
Discount rate used to determine benefit obligation at period end |  | 5.40 |  | ​ | 4.70 |  | ​ | 4.90 | ​
Expected long-term return on plan assets used for net periodic benefit cost |  | 7.00 |  | ​ | 7.00 |  | ​ | 7.00 | ​
Expected long-term return on plan assets used to determine benefit obligation at period end |  | 7.00 |  | ​ | 7.00 |  | ​ | 7.00 | ​
Summary of plan asset allocation by asset category | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31, | ​
​ |  | 2024 | ​ | ​ | 2023 | ​
Asset category: |  |  |  | ​ |  | ​
Debt securities |  | 99 | % | ​ | 100 | %
Cash equivalents |  | 1 |  | ​ | — | ​
Total |  | 100 | % | ​ | 100 | %
Summary of fair values of the plan assets | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31, 2024
​ | ​ | Fair Value Measurements Using:
​ | ​ | Quoted | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Prices in | ​ | Significant | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Active Markets for | ​ | Other | ​ | Significant | ​ | ​ | ​
​ | ​ | Identical | ​ | Observable | ​ | Unobservable | ​ | ​ | ​
(In thousands) |  | Assets (Level 1) |  | Inputs (Level 2) |  | Inputs (Level 3) |  | Total
Description: | ​ |  | ​ | ​ | ​ | ​ | ​ |  | ​ | ​ |  | ​
Cash and cash equivalents | ​ | $ | — | ​ | $ | 136 | ​ | $ | — | ​ | $ | 136
Fixed income securities: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Government | ​ | ​ | 19,070 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | 19,070
Total Plan Assets | ​ | $ | 19,070 | ​ | $ | 136 | ​ | $ | — | ​ | $ | 19,206
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31, 2023
​ | ​ | Fair Value Measurements Using:
​ | ​ | Quoted | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Prices in | ​ | Significant | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Active Markets for | ​ | Other | ​ | Significant | ​ | ​ | ​
​ | ​ | Identical | ​ | Observable | ​ | Unobservable | ​ | ​ | ​
(In thousands) |  | Assets (Level 1) |  | Inputs (Level 2) |  | Inputs (Level 3) |  | Total
Description: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Cash and cash equivalents | ​ | $ | — | ​ | $ | 58 | ​ | $ | — | ​ | $ | 58
Fixed income securities: | ​ |  | ​ | ​ |  | ​ | ​ |  | ​ | ​ |  | ​
Government | ​ |  | 21,245 | ​ |  | — | ​ |  | — | ​ |  | 21,245
Total Plan Assets | ​ | $ | 21,245 | ​ | $ | 58 | ​ | $ | — | ​ | $ | 21,303
Schedule of expected benefit payments maturities | ​
​ | ​ | ​ | ​
(In thousands) | ​ | ​
2025 | ​ | $ | 1,502
2026 | ​ |  | 1,462
2027 | ​ |  | 1,431
2028 | ​ |  | 1,393
2029 | ​ |  | 1,353
2030 to 2034 | ​ |  | 6,514
Pension Plan [Member] |
Defined Benefit Plan Disclosure |
Schedule of funded status of defined benefit plan | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year Ended December 31,
(In thousands) |  | 2024 |  | 2023
Reconciliation of projected benefit obligation: | ​ |  |  | ​ | ​ | ​
Projected benefit obligation at beginning of year | ​ | $ | 27,282 | ​ | $ | 27,920
Service cost | ​ |  | — | ​ |  | 564
Interest cost | ​ |  | 1,265 | ​ |  | 1,263
Actuarial gain | ​ | ​ | (1,575) | ​ | ​ | (883)
Curtailment | ​ | ​ | — | ​ | ​ | (446)
Impact of settlement | ​ | ​ | (5,481) | ​ | ​ | —
Benefit payments | ​ |  | (1,040) | ​ |  | (1,136)
Projected benefit obligation at end of year | ​ |  | 20,451 | ​ |  | 27,282
​ | ​ |  |  | ​ |  |
Plan assets at fair value (investments in trust funds managed by trustee) | ​ |  |  | ​ |  |
Balance at beginning of year | ​ |  | 38,170 | ​ |  | 38,572
Return on plan assets | ​ |  | (1,542) | ​ |  | 734
Impact of settlement | ​ | ​ | (5,481) | ​ | ​ | —
Benefit payments | ​ |  | (1,040) | ​ |  | (1,136)
Balance at end of year | ​ |  | 30,107 | ​ |  | 38,170
Funded status at end of year | ​ | $ | 9,656 | ​ | $ | 10,888
Schedule of components of net periodic (credit) benefit cost included in other non-interest expense | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year Ended December 31,
(In thousands) | ​ | 2024 |  | 2023
Service cost | ​ | $ | — | ​ | $ | 564
Interest cost | ​ | ​ | 1,265 | ​ | ​ | 1,263
Expected return on plan assets | ​ |  | (2,726) | ​ |  | (2,760)
Net periodic benefit credit | ​ | $ | (1,461) | ​ | $ | (933)
Settlement loss recognized | ​ | ​ | 1,215 | ​ | ​ | —
Total benefit cost | ​ | $ | (246) | ​ | $ | (933)
Schedule of change in accumulated other comprehensive loss | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year Ended December 31,
(In thousands) |  | 2024 |  | 2023
Balance at beginning of period | ​ | $ | (3,056) | ​ | $ | (2,358)
Recognition of gain as a result of settlement | ​ | ​ | 1,215 | ​ | ​ | —
Loss recognized during the year | ​ |  | (2,693) | ​ |  | (698)
Balance at the end of the period | ​ | $ | (4,534) | ​ | $ | (3,056)
Period end component of accumulated other comprehensive income, net of tax | ​ | $ | 3,143 | ​ | $ | 2,087
Schedule of major assumptions utilized to determine the net periodic cost of Plan benefit obligations | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | At or for the Year Ended December 31,
​ |  | 2024 | ​ | ​ | 2023 | ​
Discount rate used for net periodic benefit cost |  | 4.79 | % | ​ | 4.98 | %
Discount rate used to determine benefit obligation at period end |  | 5.47 |  | ​ | 4.79 | ​
Expected long-term return on plan assets used for net periodic benefit cost |  | 7.25 |  | ​ | 7.25 | ​
Expected long-term return on plan assets used to determine benefit obligation at period end |  | 7.25 |  | ​ | 7.25 | ​
Summary of plan asset allocation by asset category | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31, | ​
​ |  | 2024 | ​ | ​ | 2023 | ​
Asset category: |  |  |  | ​ |  |
Debt securities |  | 96 | % | ​ | 99 | %
Cash equivalents |  | 4 |  | ​ | 1 |
Total |  | 100 | % | ​ | 100 | %
Summary of fair values of the plan assets | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Fair Value Measurements
​ | ​ | at December 31, 2024
​ | ​ | Quoted | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Prices in | ​ | Significant | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Active Markets for | ​ | Other | ​ | Significant | ​ | ​ | ​
​ | ​ | Identical | ​ | Observable | ​ | Unobservable | ​ | ​ | ​
(In thousands) |  | Assets (Level 1) |  | Inputs (Level 2) |  | Inputs (Level 3) |  | Total
Description: | ​ |  | ​ | ​ | ​ | ​ | ​ |  | ​ | ​ |  | ​
Cash and cash equivalents | ​ | $ | — | ​ | $ | 1,062 | ​ | $ | — | ​ | $ | 1,062
Fixed income securities: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Government | ​ | ​ | 29,045 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | 29,045
Total Plan Assets | ​ | $ | 29,045 | ​ | $ | 1,062 | ​ | $ | — | ​ | $ | 30,107
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | Fair Value Measurements
​ | ​ | at December 31, 2023
​ | ​ | Quoted | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Prices in | ​ | Significant | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Active Markets for | ​ | Other | ​ | Significant | ​ | ​ | ​
​ | ​ | Identical | ​ | Observable | ​ | Unobservable | ​ | ​ | ​
(In thousands) |  | Assets (Level 1) |  | Inputs (Level 2) |  | Inputs (Level 3) |  | Total
Description: | ​ |  | ​ | ​ |  | ​ | ​ |  | ​ | ​ |  | ​
Cash and cash equivalents | ​ | $ | — | ​ | $ | 317 | ​ | $ | — | ​ | $ | 317
Fixed income securities: | ​ |  | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Government | ​ |  | 37,853 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | 37,853
Total Plan Assets | ​ | $ | 37,853 | ​ | $ | 317 | ​ | $ | — | ​ | $ | 38,170
Schedule of expected benefit payments maturities | ​
​ | ​ | ​ | ​
(In thousands) | ​ | ​
2025 | ​ | $ | 1,128
2026 | ​ |  | 1,302
2027 | ​ |  | 1,207
2028 | ​ |  | 1,294
2029 | ​ |  | 1,300
2030 to 2034 | ​ |  | 7,689

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