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Securities Securities - Allowance for Credit Losses on Held to Maturity Securities (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019 | Jun. 30, 2020 | Jan. 01, 2020 | Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items] |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss | $ 160 |  | $ 160 |  |  |  | $ 0
Impact of adopting ASC 326 | 0 | $ 0 | 39,377 | $ 0 |  |  |
Debt Securities [Member] |  |  |  |  |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss | 160 |  | 160 |  | $ 172 |  | 0
Impact of adopting ASC 326 | 0 |  | 215 |  |  |  |
Credit loss expense (benefit) | (12) |  | (55) |  |  |  |
Debt Securities [Member] | Impact of Adoption [Member] |  |  |  |  |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  |  |  |  | $ 215 |
States and political subdivisions [Member] |  |  |  |  |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss | $ 160 |  | $ 160 |  |  |  | $ 0
States and political subdivisions [Member] | Impact of Adoption [Member] |  |  |  |  |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  |  |  |  | $ 215 |

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- Definition Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aaa) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details
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