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Securities (Tables) | 9 Months Ended
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Sep. 30, 2021
Securities |
Schedule of amortized cost and estimated fair value of debt securities | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | Mortgage-backed | ​ | Collateralized | ​ | ​ | ​
​ | ​ | U.S. government | ​ | Municipal | ​ | residential | ​ | mortgage | ​ | Total available-for-
September 30, 2021 |  | agency obligations |  | obligations |  | obligations |  | obligations |  | sale
​ |  | (Dollars in thousands)
1 year or less | ​ | $ | — |  | $ | 1,231 |  | $ | 456 |  | $ | 1,071 | ​ | $ | 2,758
1 to 5 years | ​ |  | 3,938 |  | ​ | 3,777 |  | ​ | 31,185 |  | ​ | 17,535 | ​ |  | 56,435
5 to 10 years | ​ |  | 6,507 |  | ​ | 2,867 |  | ​ | 13,837 |  | ​ | 9,984 | ​ |  | 33,195
After 10 years | ​ |  | — |  | ​ | 2,970 |  | ​ | — |  | ​ | 1,636 | ​ |  | 4,606
Fair value | ​ |  | 10,445 |  | ​ | 10,845 |  | ​ | 45,478 |  | ​ | 30,226 | ​ |  | 96,994
Gross unrealized gains | ​ |  | 163 |  | ​ | 464 |  | ​ | 426 |  | ​ | 441 | ​ |  | 1,494
Gross unrealized losses | ​ |  | (39) |  | ​ | (12) |  | ​ | (309) |  | ​ | (259) | ​ |  | (619)
Amortized cost | ​ | $ | 10,321 | ​ | $ | 10,393 | ​ | $ | 45,361 | ​ | $ | 30,044 | ​ | $ | 96,119
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | Mortgage-backed | ​ | Collateralized | ​ | ​ | ​
​ | ​ | U.S. government | ​ | Municipal | ​ | residential | ​ | mortgage | ​ | Total available-for-
December 31, 2020 |  | agency obligations |  | obligations |  | obligations |  | obligations |  | sale
​ |  | (Dollars in thousands)
1 year or less | ​ | $ | 1,000 |  | $ | 768 |  | $ | 1,443 |  | $ | 383 | ​ | $ | 3,594
1 to 5 years | ​ |  | 4,862 |  | ​ | 3,726 |  | ​ | 34,486 |  | ​ | 14,452 | ​ |  | 57,526
5 to 10 years | ​ |  | 1,285 |  | ​ | 4,354 |  | ​ | 7,165 |  | ​ | 5,564 | ​ |  | 18,368
After 10 years | ​ |  | — |  | ​ | 2,132 |  | ​ | — |  | ​ | — | ​ |  | 2,132
Fair value | ​ |  | 7,147 |  | ​ | 10,980 |  | ​ | 43,094 |  | ​ | 20,399 | ​ |  | 81,620
Gross unrealized gains | ​ |  | 154 |  | ​ | 518 |  | ​ | 884 |  | ​ | 534 | ​ |  | 2,090
Gross unrealized losses | ​ |  | (17) |  | ​ | (18) |  | ​ | (22) |  | ​ | (66) | ​ |  | (123)
Amortized cost | ​ | $ | 7,010 |  | $ | 10,480 |  | $ | 42,232 |  | $ | 19,931 | ​ | $ | 79,653
Schedule of securities with gross unrealized losses | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Less than 12 Months | ​ | 12 Months or Longer | ​ | Total
​ | ​ | (Dollars in thousands)
​ | ​ | Fair | ​ | Unrealized | ​ | Fair | ​ | Unrealized | ​ | Fair | ​ | Unrealized
​ |  | Value |  | Losses |  | Value |  | Losses |  | Value |  | Losses
September 30, 2021 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. government agency obligations | ​ | $ | 2,383 |  | $ | 23 |  | $ | 1,154 |  | $ | 16 |  | $ | 3,537 | ​ | $ | 39
Municipal obligations | ​ |  | — |  | ​ | — |  | ​ | 242 |  | ​ | 12 |  | ​ | 242 | ​ |  | 12
Mortgage-backed residential obligations | ​ |  | 19,537 |  | ​ | 284 |  | ​ | 2,213 |  | ​ | 25 |  | ​ | 21,750 | ​ |  | 309
Collateralized mortgage obligations | ​ |  | 18,762 |  | ​ | 259 |  | ​ | — |  | ​ | — |  | ​ | 18,762 | ​ |  | 259
Total | ​ | $ | 40,682 |  | $ | 566 |  | $ | 3,609 |  | $ | 53 |  | $ | 44,291 | ​ | $ | 619
December 31, 2020 | ​ |  |  |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  | ​ |  |
U.S. government agency obligations | ​ | $ | 1,284 |  | $ | 17 |  | $ | — |  | $ | — |  | $ | 1,284 | ​ | $ | 17
Municipal obligations | ​ |  | — |  | ​ | — |  | ​ | 238 |  | ​ | 18 |  | ​ | 238 | ​ |  | 18
Mortgage-backed residential obligations | ​ |  | 5,265 |  | ​ | 17 |  | ​ | 1,170 |  | ​ | 5 |  | ​ | 6,435 | ​ |  | 22
Collateralized mortgage obligations | ​ |  | 8,694 |  | ​ | 66 |  | ​ | 241 |  | ​ | — |  | ​ | 8,935 | ​ |  | 66
Total | ​ | $ | 15,243 |  | $ | 100 |  | $ | 1,649 |  | $ | 23 |  | $ | 16,892 | ​ | $ | 123
Schedule of proceeds from sales of securities available-for-sale, as well as gross gains and losses | The following table provides a summary of the proceeds from sales of securities available-for-sale, as well as gross gains and losses, for the periods presented. ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Three months ended September 30, | ​ | Nine months ended September 30,
​ |  | 2021 |  | 2020 |  | 2021 |  | 2020
​ | ​ | (Dollars in thousands)
Proceeds from sales of securities available-for-sale | ​ | $ | 6,769 | ​ | $ | — | ​ | $ | 6,769 | ​ | $ | 12,112
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Gross realized gains | ​ |  | 131 | ​ |  | — | ​ |  | 131 | ​ |  | 114
Gross realized losses | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | (55)

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- Definition Tabular disclosure of fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) and unrealized loss in unrealized loss position , without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References No definition available. + Details
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- Definition Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -URI http://asc.fasb.org/topic&trid=2196928 + Details
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- Definition Tabular disclosure of the proceeds from sales of available-for-sale securities and the gross realized gains and gross realized losses that have been included in earnings as a result of those sales. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27357-111563 + Details
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