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Investment Securities - Narrative (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Investment Securities [Member] |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |
Proceeds from Sale of Available-for-sale Securities | $ 0 | $ 10,218 | $ 186,769
Proceeds from Sale of Debt Securities, Available-for-sale |  | 10,200 | 186,800
Available-for-sale Securities, Gross Realized Losses | $ 0 | 0 | 100
Available-for-sale Securities, Gross Realized Gains |  | $ 100 | $ 100
Fixed Interest Rate [Member] | Government/GSE Guaranteed Mortgage Backed Securities [Member] |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |
Held-to-Maturity Securities, Debt Maturities, Weighted-Average Yield | 3.50% | 2.50% |
Debt Securities, Held-to-maturity, Amortized Cost, before Other-than-temporary Impairment | $ 45,032 | $ 45,032 |
Debt Securities, Held-to-maturity, Fair Value | $ 45,594 | $ 45,564 |

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- Definition Amount of realized gain on 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/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
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- Definition Amount of realized loss on 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/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
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