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Investment Securities (Tables) | 12 Months Ended
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Dec. 31, 2022
Investment Securities |
Schedule of amortized cost of investment securities to estimated fair values | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31, 2022
​ | ​ | Amortized | ​ | Unrealized | ​ | Unrealized | ​ | Fair
(dollars in thousands) |  | Cost | ​ | Gains | ​ | Losses |  | Value
Available-for-sale | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. Treasury and agencies | ​ | $ | 3,518 | ​ | $ | 19 | ​ | $ | (17) | ​ | $ | 3,520
Mortgage backed securities | ​ |  |  | ​ |  | ​ | ​ |  | ​ | ​ |  | ​
Residential agency | ​ |  | 705,845 | ​ |  | 2 | ​ |  | (118,168) | ​ |  | 587,679
Commercial | ​ |  | 70,669 | ​ |  | — | ​ |  | (7,111) | ​ |  | 63,558
Asset backed securities | ​ |  | 34 | ​ |  | — | ​ |  | — | ​ |  | 34
Corporate bonds | ​ |  | 69,501 | ​ |  | — | ​ |  | (6,968) | ​ |  | 62,533
Total available-for-sale investment securities | ​ | ​ | 849,567 | ​ | ​ | 21 | ​ | ​ | (132,264) | ​ | ​ | 717,324
Held-to-maturity | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Obligations of state and political agencies | ​ | ​ | 137,787 | ​ |  | — | ​ |  | (17,736) | ​ |  | 120,051
Mortgage backed securities | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Residential agency | ​ | ​ | 184,115 | ​ |  | — | ​ |  | (33,254) | ​ |  | 150,861
Total held-to-maturity investment securities | ​ | ​ | 321,902 | ​ | ​ | — | ​ | ​ | (50,990) | ​ | ​ | 270,912
Total investment securities | ​ | $ | 1,171,469 | ​ | $ | 21 | ​ | $ | (183,254) | ​ | $ | 988,236
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31, 2021
​ | ​ | Amortized | ​ | Unrealized | ​ | Unrealized | ​ | Fair
(dollars in thousands) |  | Cost | ​ | Gains | ​ | Losses |  | Value
Available-for-sale | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. Treasury and agencies | ​ | $ | 5,028 | ​ | $ | 75 | ​ | $ | — | ​ | $ | 5,103
Mortgage backed securities | ​ |  |  | ​ |  | ​ | ​ |  | ​ | ​ |  |
Residential agency | ​ |  | 717,781 | ​ |  | 1,213 | ​ |  | (11,837) | ​ |  | 707,157
Commercial | ​ |  | 88,362 | ​ |  | 2,674 | ​ |  | (123) | ​ |  | 90,913
Asset backed securities | ​ |  | 52 | ​ | ​ | 2 | ​ |  | — | ​ |  | 54
Corporate bonds | ​ |  | 49,035 | ​ |  | 1,398 | ​ |  | (11) | ​ |  | 50,422
Total available-for-sale investment securities | ​ | ​ | 860,258 | ​ | ​ | 5,362 | ​ | ​ | (11,971) | ​ | ​ | 853,649
Held-to-maturity | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Obligations of state and political agencies | ​ | ​ | 144,543 | ​ | ​ | 1,110 | ​ | ​ | (349) | ​ | ​ | 145,304
Mortgage backed securities | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Residential agency | ​ | ​ | 207,518 | ​ | ​ | — | ​ | ​ | (3,145) | ​ | ​ | 204,373
Total held-to-maturity investment securities | ​ | ​ | 352,061 | ​ | ​ | 1,110 | ​ | ​ | (3,494) | ​ | ​ | 349,677
Total investment securities | ​ | $ | 1,212,319 | ​ | $ | 6,472 | ​ | $ | (15,465) | ​ | $ | 1,203,326
​
Schedule of contractual maturity of amortized cost and estimated fair value | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Held-to-maturity | ​ | Available-for-sale
​ | ​ | Carrying | ​ | Fair | ​ | Amortized | ​ | Fair
(dollars in thousands) |  | Value | ​ | Value | ​ | Cost |  | Value
Due within one year or less | ​ | $ | 6,554 | ​ | $ | 6,522 | ​ | $ | 4 | ​ | $ | 4
Due after one year through five years | ​ |  | 40,317 | ​ |  | 37,146 | ​ |  | 21,256 | ​ |  | 19,863
Due after five years through ten years | ​ |  | 69,992 | ​ |  | 59,138 | ​ |  | 87,961 | ​ |  | 79,697
Due after 10 years | ​ |  | 205,039 | ​ |  | 168,106 | ​ |  | 740,346 | ​ |  | 617,760
Total investment securities | ​ | $ | 321,902 | ​ | $ | 270,912 | ​ | $ | 849,567 | ​ | $ | 717,324
​
Schedule of proceeds from the sale of available for sale securities | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year ended
​ | ​ | December 31,
(dollars in thousands) |  | 2022 |  | 2021 |  | 2020
Proceeds | ​ | $ | — | ​ | $ | 13,189 | ​ | $ | 75,647
Realized gains | ​ |  | — | ​ |  | 114 | ​ | ​ | 2,737
Realized losses | ​ |  | — | ​ |  | — | ​ | ​ | —
​
Schedule of proceeds from the call of held-to-maturity investment securities | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year ended
​ | ​ | December 31,
(dollars in thousands) |  | 2022 |  | 2021 |  | 2020
Proceeds | ​ | $ | 963 | ​ | $ | 1,772 | ​ | $ | —
Realized gains | ​ |  | — | ​ |  | 11 | ​ | ​ | —
Realized losses | ​ |  | — | ​ |  | — | ​ | ​ | —
​
Schedule of investment securities with gross unrealized losses | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31, 2022
​ | ​ | Less than 12 Months | ​ | Over 12 Months | ​ | Total
​ | ​ | Unrealized | ​ | Fair | ​ | Unrealized | ​ | Fair | ​ | Unrealized | ​ | Fair
(dollars in thousands) |  | Losses |  | Value |  | Losses |  | Value |  | Losses |  | Value
Available-for-sale | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. Treasury and agencies | ​ | $ | (17) | ​ | $ | 509 | ​ | $ | — | ​ | $ | — | ​ | $ | (17) | ​ | $ | 509
Mortgage backed securities | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |
Residential agency | ​ |  | (10,457) | ​ |  | 79,693 | ​ |  | (107,711) | ​ |  | 507,418 | ​ |  | (118,168) | ​ |  | 587,111
Commercial | ​ |  | (4,835) | ​ |  | 50,437 | ​ |  | (2,276) | ​ |  | 13,120 | ​ |  | (7,111) | ​ |  | 63,557
Asset backed securities | ​ |  | — | ​ |  | 32 | ​ |  | — | ​ |  | 2 | ​ |  | — | ​ |  | 34
Corporate bonds | ​ |  | (4,452) | ​ |  | 48,048 | ​ |  | (2,516) | ​ |  | 14,484 | ​ |  | (6,968) | ​ |  | 62,532
Total available-for-sale investment securities | ​ | ​ | (19,761) | ​ | ​ | 178,719 | ​ | ​ | (112,503) | ​ | ​ | 535,024 | ​ | ​ | (132,264) | ​ | ​ | 713,743
Held-to-maturity | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Obligations of state and political agencies | ​ | ​ | (3,336) | ​ | ​ | 18,788 | ​ | ​ | (14,400) | ​ | ​ | 98,762 | ​ | ​ | (17,736) | ​ | ​ | 117,550
Mortgage backed securities | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Residential agency | ​ | ​ | — | ​ | ​ | — | ​ | ​ | (33,254) | ​ | ​ | 150,861 | ​ | ​ | (33,254) | ​ | ​ | 150,861
Total held-to-maturity investment securities | ​ | ​ | (3,336) | ​ | ​ | 18,788 | ​ | ​ | (47,654) | ​ | ​ | 249,623 | ​ | ​ | (50,990) | ​ | ​ | 268,411
Total investment securities | ​ | $ | (23,097) | ​ | $ | 197,507 | ​ | $ | (160,157) | ​ | $ | 784,647 | ​ | $ | (183,254) | ​ | $ | 982,154
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31, 2021
​ | ​ | Less than 12 Months | ​ | Over 12 Months | ​ | Total
​ | ​ | Unrealized | ​ | Fair | ​ | Unrealized | ​ | Fair | ​ | Unrealized | ​ | Fair
(dollars in thousands) |  | Losses |  | Value |  | Losses |  | Value |  | Losses |  | Value
Available-for-sale | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. Treasury and agencies | ​ | $ | — | ​ | $ | — | ​ | $ | — | ​ | $ | — | ​ | $ | — | ​ | $ | —
Mortgage backed securities | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |
Residential agency | ​ |  | (10,156) | ​ |  | 554,811 | ​ |  | (1,681) | ​ |  | 55,082 | ​ |  | (11,837) | ​ |  | 609,893
Commercial | ​ |  | (123) | ​ |  | 17,470 | ​ |  | — | ​ |  | — | ​ |  | (123) | ​ |  | 17,470
Asset backed securities | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | 2 | ​ |  | — | ​ |  | 2
Corporate bonds | ​ |  | (11) | ​ |  | 5,989 | ​ |  | — | ​ |  | — | ​ |  | (11) | ​ |  | 5,989
Total available-for-sale investment securities | ​ | ​ | (10,290) | ​ | ​ | 578,270 | ​ | ​ | (1,681) | ​ | ​ | 55,084 | ​ | ​ | (11,971) | ​ | ​ | 633,354
Held-to-maturity | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Obligations of state and political agencies | ​ | ​ | (349) | ​ | ​ | 53,210 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | (349) | ​ | ​ | 53,210
Mortgage backed securities | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Residential agency | ​ | ​ | (3,145) | ​ | ​ | 204,373 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | (3,145) | ​ | ​ | 204,373
Total held-to-maturity investment securities | ​ | ​ | (3,494) | ​ | ​ | 257,583 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | (3,494) | ​ | ​ | 257,583
Total investment securities | ​ | $ | (13,784) | ​ | $ | 835,853 | ​ | $ | (1,681) | ​ | $ | 55,084 | ​ | $ | (15,465) | ​ | $ | 890,937
​
Schedule of federal home loan bank | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31, | ​ | December 31,
(dollars in thousands) |  | 2022 |  | 2021
Federal Reserve | ​ | $ | 4,595 | ​ | $ | 2,675
FHLB | ​ |  | 19,362 | ​ |  | 3,806
​

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