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Allowance for Loan Losses (the Allowance) - Allowance allocated by portfolio segment (Details) - USD ($) $ in Thousands | Mar. 31, 2021 | Dec. 31, 2020 | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | --- | --- | ---
Impaired Loans |  |  |  |
Allowance on loans and leases individually evaluated for impairment | $ 2,018 | $ 1,645 |  |
Allowance on loans and leases collectively evaluated for impairment | 16,358 | 16,122 |  |
Total | 18,376 | 17,767 | $ 11,098 | $ 9,513
Carrying value of loans and leases individually evaluated for impairment | 10,226 | 10,380 |  |
Carrying value of loans and leases collectively evaluated for impairment | 1,335,232 | 1,267,194 |  |
Total | 1,345,458 | 1,277,574 |  |
Commercial mortgage |  |  |  |
Impaired Loans |  |  |  |
Allowance on loans and leases collectively evaluated for impairment | 7,655 | 7,451 |  |
Total | 7,655 | 7,451 | 4,112 | 3,426
Carrying value of loans and leases individually evaluated for impairment | 730 | 1,606 |  |
Carrying value of loans and leases collectively evaluated for impairment | 516,691 | 483,497 |  |
Total | 517,421 | 485,103 |  |
Home equity lines and loans |  |  |  |
Impaired Loans |  |  |  |
Allowance on loans and leases individually evaluated for impairment | 8 | 9 |  |
Allowance on loans and leases collectively evaluated for impairment | 302 | 425 |  |
Total | 310 | 434 | 484 | 342
Carrying value of loans and leases individually evaluated for impairment | 919 | 921 |  |
Carrying value of loans and leases collectively evaluated for impairment | 54,659 | 64,066 |  |
Total | 55,578 | 64,987 |  |
Residential mortgage |  |  |  |
Impaired Loans |  |  |  |
Allowance on loans and leases individually evaluated for impairment | 72 | 73 |  |
Allowance on loans and leases collectively evaluated for impairment | 242 | 312 |  |
Total | 314 | 385 | 219 | 179
Carrying value of loans and leases individually evaluated for impairment | 1,814 | 1,817 |  |
Carrying value of loans and leases collectively evaluated for impairment | 33,681 | 38,455 |  |
Total | 35,495 | 40,272 |  |
Construction |  |  |  |
Impaired Loans |  |  |  |
Allowance on loans and leases collectively evaluated for impairment | 2,311 | 2,421 |  |
Total | 2,311 | 2,421 | 2,381 | 2,362
Carrying value of loans and leases individually evaluated for impairment | 1,206 | 1,206 |  |
Carrying value of loans and leases collectively evaluated for impairment | 133,395 | 139,040 |  |
Total | 134,601 | 140,246 |  |
Commercial and industrial, including leases |  |  |  |
Impaired Loans |  |  |  |
Allowance on loans and leases individually evaluated for impairment | 1,562 | 1,563 |  |
Allowance on loans and leases collectively evaluated for impairment | 3,724 | 3,868 |  |
Total | 5,286 | 5,431 | 3,169 | 2,684
Carrying value of loans and leases individually evaluated for impairment | 4,339 | 4,645 |  |
Carrying value of loans and leases collectively evaluated for impairment | 257,082 | 257,105 |  |
Total | 261,421 | 261,750 |  |
Small business loans |  |  |  |
Impaired Loans |  |  |  |
Allowance on loans and leases individually evaluated for impairment | 376 |  |  |
Allowance on loans and leases collectively evaluated for impairment | 1,544 | 1,259 |  |
Total | 1,920 | 1,259 | 725 | 509
Carrying value of loans and leases individually evaluated for impairment | 1,087 | 185 |  |
Carrying value of loans and leases collectively evaluated for impairment | 61,286 | 49,357 |  |
Total | 62,373 | 49,542 |  |
Paycheck Protection Program loans ("PPP") |  |  |  |
Impaired Loans |  |  |  |
Carrying value of loans and leases collectively evaluated for impairment | 230,847 | 203,543 |  |
Total | 230,847 | 203,543 |  |
MainStreet Lending Program Loans ("PPP") |  |  |  |
Impaired Loans |  |  |  |
Carrying value of loans and leases collectively evaluated for impairment | 583 | 580 |  |
Total | 583 | 580 |  |
Consumer |  |  |  |
Impaired Loans |  |  |  |
Allowance on loans and leases collectively evaluated for impairment | 4 | 4 |  |
Total | 4 | 4 | 4 | 6
Carrying value of loans and leases collectively evaluated for impairment | 469 | 511 |  |
Total | 469 | 511 |  |
Leases |  |  |  |
Impaired Loans |  |  |  |
Allowance on loans and leases collectively evaluated for impairment | 576 | 382 |  |
Total | 576 | 382 | $ 4 | $ 5
Carrying value of loans and leases individually evaluated for impairment | 131 |  |  |
Carrying value of loans and leases collectively evaluated for impairment | 46,539 | 31,040 |  |
Total | $ 46,670 | $ 31,040 |  |

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- Definition The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 + Details
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