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Investment Securities - Schedule Of Investments Within The Available For Sale Portfolio That Had Unrealized Losses (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Schedule of Investments [Line Items] |  |
Less than 12 months | $ 1,541,140 | $ 655,820
12 months or longer | 0 | 553,979
Total fair value | 1,541,140 | 1,209,799
Unrealized Losses |  |
Less than 12 months | (3,610) | (3,616)
12 months or longer | 0 | (7,288)
Total unrealized losses | (3,610) | (10,904)
U.S. treasuries |  |
Schedule of Investments [Line Items] |  |
Less than 12 months | 299,934 | 0
12 months or longer | 0 | 100
Total fair value | 299,934 | 100
Unrealized Losses |  |
Less than 12 months | (3) | 0
12 months or longer | 0 | 0
Total unrealized losses | (3) | 0
Government agency issued MBS |  |
Schedule of Investments [Line Items] |  |
Less than 12 months | 568,733 | 174,983
12 months or longer | 0 | 192,755
Total fair value | 568,733 | 367,738
Unrealized Losses |  |
Less than 12 months | (2,158) | (495)
12 months or longer | 0 | (2,061)
Total unrealized losses | (2,158) | (2,556)
Government agency issued CMO |  |
Schedule of Investments [Line Items] |  |
Less than 12 months | 636,386 | 378,815
12 months or longer | 0 | 361,124
Total fair value | 636,386 | 739,939
Unrealized Losses |  |
Less than 12 months | (1,439) | (1,970)
12 months or longer | 0 | (5,227)
Total unrealized losses | (1,439) | (7,197)
Other U.S. government agencies |  |
Schedule of Investments [Line Items] |  |
Less than 12 months | 30,896 | 98,471
12 months or longer | 0 | 0
Total fair value | 30,896 | 98,471
Unrealized Losses |  |
Less than 12 months | (4) | (1,121)
12 months or longer | 0 | 0
Total unrealized losses | (4) | (1,121)
States and municipalities |  |
Schedule of Investments [Line Items] |  |
Less than 12 months | 5,191 | 3,551
12 months or longer | 0 | 0
Total fair value | 5,191 | 3,551
Unrealized Losses |  |
Less than 12 months | (6) | (30)
12 months or longer | 0 | 0
Total unrealized losses | $ (6) | $ (30)

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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922890-210455 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27337-111563 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=121590138&loc=SL82922954-210456 + Details
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