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Investment Securities (Tables) | 3 Months Ended
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Mar. 31, 2024
Investment Securities |
Schedule of amortized cost of investment securities to estimated fair values | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | March 31, 2024
​ | ​ | Amortized | ​ | Unrealized | ​ | Unrealized | ​ | Allowance for | ​ | Fair
(dollars in thousands) |  | Cost | ​ | Gains | ​ | Losses | ​ | Credit Losses |  | Value
Available-for-sale | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. Treasury and agencies | ​ | $ | 839 | ​ | $ | 2 | ​ | $ | (3) | ​ | $ | — | ​ | $ | 838
Mortgage backed securities | ​ |  |  | ​ |  | ​ | ​ |  | ​ | ​ | ​ | ​ | ​ |  | ​
Residential agency | ​ |  | 513,409 | ​ |  | — | ​ |  | (92,516) | ​ | ​ | — | ​ |  | 420,893
Commercial | ​ |  | 1,471 | ​ |  | — | ​ |  | (120) | ​ | ​ | — | ​ |  | 1,351
Asset backed securities | ​ |  | 23 | ​ |  | — | ​ |  | (1) | ​ | ​ | — | ​ |  | 22
Corporate bonds | ​ |  | 57,991 | ​ |  | — | ​ |  | (8,823) | ​ | ​ | — | ​ |  | 49,168
Total available-for-sale investment securities | ​ | ​ | 573,733 | ​ | ​ | 2 | ​ | ​ | (101,463) | ​ | ​ | — | ​ | ​ | 472,272
Held-to-maturity | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Obligations of state and political agencies | ​ | ​ | 124,971 | ​ |  | — | ​ |  | (12,985) | ​ | ​ | 110 | ​ |  | 111,986
Mortgage backed securities | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Residential agency | ​ | ​ | 167,168 | ​ |  | — | ​ |  | (29,347) | ​ | ​ | 97 | ​ |  | 137,821
Total held-to-maturity investment securities | ​ | ​ | 292,139 | ​ | ​ | — | ​ | ​ | (42,332) | ​ | ​ | 207 | ​ | ​ | 249,807
Total investment securities | ​ | $ | 865,872 | ​ | $ | 2 | ​ | $ | (143,795) | ​ | $ | 207 | ​ | $ | 722,079
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31, 2023
​ | ​ | Amortized | ​ | Unrealized | ​ | Unrealized | ​ | Allowance for | ​ | Fair
(dollars in thousands) |  | Cost | ​ | Gains | ​ | Losses | ​ | Credit Losses |  | Value
Available-for-sale | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. Treasury and agencies | ​ | $ | 1,119 | ​ | $ | 4 | ​ | $ | (3) | ​ | ​ | — | ​ | $ | 1,120
Mortgage backed securities | ​ |  |  | ​ |  | ​ | ​ |  | ​ | ​ | ​ | ​ | ​ |  |
Residential agency | ​ |  | 524,140 | ​ |  | 1 | ​ |  | (88,547) | ​ | ​ | — | ​ |  | 435,594
Commercial | ​ |  | 1,476 | ​ |  | — | ​ |  | (123) | ​ | ​ | — | ​ |  | 1,353
Asset backed securities | ​ |  | 26 | ​ |  | — | ​ |  | (1) | ​ | ​ | — | ​ |  | 25
Corporate bonds | ​ |  | 57,993 | ​ |  | — | ​ |  | (9,349) | ​ | ​ | — | ​ |  | 48,644
Total available-for-sale investment securities | ​ | ​ | 584,754 | ​ | ​ | 5 | ​ | ​ | (98,023) | ​ | ​ | — | ​ | ​ | 486,736
Held-to-maturity | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Obligations of state and political agencies | ​ | ​ | 129,603 | ​ |  | — | ​ |  | (12,613) | ​ | ​ | 114 | ​ | ​ | 116,990
Mortgage backed securities | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Residential agency | ​ | ​ | 170,125 | ​ |  | — | ​ |  | (28,498) | ​ | ​ | 99 | ​ | ​ | 141,627
Total held-to-maturity investment securities | ​ | ​ | 299,728 | ​ | ​ | — | ​ | ​ | (41,111) | ​ | ​ | 213 | ​ | ​ | 258,617
Total investment securities | ​ | $ | 884,482 | ​ | $ | 5 | ​ | $ | (139,134) | ​ | $ | 213 | ​ | $ | 745,353
Schedule of investment securities with gross unrealized losses | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | March 31, 2024
​ | ​ | ​ | ​ | Less than 12 Months | ​ | Over 12 Months | ​ | Total
​ | ​ | Number of | ​ | Unrealized | ​ | Fair | ​ | Unrealized | ​ | Fair | ​ | Unrealized | ​ | Fair
(dollars in thousands) |  | Holdings | ​ | Losses |  | Value |  | Losses |  | Value |  | Losses |  | Value
Available-for-sale | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. Treasury and agencies | ​ | 1 | ​ | $ | (3) | ​ | $ | 454 | ​ | $ | — | ​ | $ | — | ​ | $ | (3) | ​ | $ | 454
Mortgage backed securities | ​ | ​ | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |
Residential agency | ​ | 111 | ​ |  | — | ​ |  | 35 | ​ |  | (92,516) | ​ |  | 420,815 | ​ |  | (92,516) | ​ |  | 420,850
Commercial | ​ | 1 | ​ |  | — | ​ |  | — | ​ |  | (120) | ​ |  | 1,351 | ​ |  | (120) | ​ |  | 1,351
Asset backed securities | ​ | 3 | ​ |  | — | ​ |  | — | ​ |  | (1) | ​ |  | 22 | ​ |  | (1) | ​ |  | 22
Corporate bonds | ​ | 12 | ​ |  | — | ​ |  | — | ​ |  | (8,823) | ​ |  | 49,168 | ​ |  | (8,823) | ​ |  | 49,168
Total available-for-sale investment securities | ​ | 128 | ​ | $ | (3) | ​ | $ | 489 | ​ | $ | (101,460) | ​ | $ | 471,356 | ​ | $ | (101,463) | ​ | $ | 471,845
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | December 31, 2023
​ | ​ | ​ | ​ | Less than 12 Months | ​ | Over 12 Months | ​ | Total
​ | ​ | Number of | ​ | Unrealized | ​ | Fair | ​ | Unrealized | ​ | Fair | ​ | Unrealized | ​ | Fair
(dollars in thousands) |  | Holdings | ​ | Losses |  | Value |  | Losses |  | Value |  | Losses |  | Value
Available-for-sale | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. Treasury and agencies | ​ | 1 | ​ | $ | (3) | ​ | $ | 489 | ​ | $ | — | ​ | $ | — | ​ | $ | (3) | ​ | $ | 489
Mortgage backed securities | ​ | ​ | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |
Residential agency | ​ | 112 | ​ |  | — | ​ |  | 43 | ​ |  | (88,547) | ​ |  | 435,505 | ​ |  | (88,547) | ​ |  | 435,548
Commercial | ​ | 1 | ​ |  | — | ​ |  | — | ​ |  | (123) | ​ |  | 1,353 | ​ |  | (123) | ​ |  | 1,353
Asset backed securities | ​ | 3 | ​ |  | — | ​ |  | — | ​ |  | (1) | ​ |  | 25 | ​ |  | (1) | ​ |  | 25
Corporate bonds | ​ | 12 | ​ |  | — | ​ |  | — | ​ |  | (9,349) | ​ |  | 48,644 | ​ |  | (9,349) | ​ |  | 48,644
Total available-for-sale investment securities | ​ | 129 | ​ | $ | (3) | ​ | $ | 532 | ​ | $ | (98,020) | ​ | $ | 485,527 | ​ | $ | (98,023) | ​ | $ | 486,059
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Schedule of amortized cost and fair value of investment securities by contractual maturity | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Held-to-maturity | ​ | Available-for-sale
​ | ​ | Carrying | ​ | Fair | ​ | Amortized | ​ | Fair
(dollars in thousands) |  | Value | ​ | Value | ​ | Cost |  | Value
Due within one year or less | ​ | $ | 8,161 | ​ | $ | 7,974 | ​ | $ | — | ​ | $ | —
Due after one year through five years | ​ |  | 47,376 | ​ |  | 43,614 | ​ |  | 473 | ​ |  | 470
Due after five years through ten years | ​ |  | 57,248 | ​ |  | 49,662 | ​ |  | 59,467 | ​ |  | 50,524
Due after 10 years | ​ |  | 12,186 | ​ |  | 10,736 | ​ |  | 384 | ​ |  | 385
​ | ​ | ​ | 124,971 | ​ | ​ | 111,986 | ​ | ​ | 60,324 | ​ | ​ | 51,379
Mortgage-backed securities | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Residential agency | ​ | ​ | 167,168 | ​ | ​ | 137,821 | ​ | ​ | 513,409 | ​ | ​ | 420,893
Total investment securities | ​ | $ | 292,139 | ​ | $ | 249,807 | ​ | $ | 573,733 | ​ | $ | 472,272
Schedule of carrying value of stock | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | March 31, | ​ | December 31,
(dollars in thousands) |  | 2024 |  | 2023
Federal Reserve | ​ | $ | 4,623 | ​ | $ | 4,623
FHLB | ​ |  | 11,491 | ​ |  | 16,566

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