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Investment Securities - Schedule Of Investments Within The Available For Sale Portfolio That Had Unrealized Losses (Details) - USD ($) $ in Millions | Sep. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Schedule of Investments [Line Items] |  |
Less than 12 months | $ 3,946 | $ 1,400
12 months or longer | 278 | 0
Total fair value | 4,224 | 1,400
Unrealized Losses |  |
Less than 12 months | (71) | (6)
12 months or longer | (10) | 0
Total unrealized losses | (81) | (6)
U.S. treasuries |  |
Schedule of Investments [Line Items] |  |
Less than 12 months |  | 307
12 months or longer |  | 0
Total fair value |  | 307
Unrealized Losses |  |
Less than 12 months |  | 0
12 months or longer |  | 0
Total unrealized losses |  | 0
Government agency issued MBS |  |
Schedule of Investments [Line Items] |  |
Less than 12 months | 2,101 | 426
12 months or longer | 99 | 0
Total fair value | 2,200 | 426
Unrealized Losses |  |
Less than 12 months | (33) | (2)
12 months or longer | (4) | 0
Total unrealized losses | (37) | (2)
Government agency issued CMO |  |
Schedule of Investments [Line Items] |  |
Less than 12 months | 1,243 | 586
12 months or longer | 179 | 0
Total fair value | 1,422 | 586
Unrealized Losses |  |
Less than 12 months | (25) | (3)
12 months or longer | (6) | 0
Total unrealized losses | (31) | (3)
Other U.S. government agencies |  |
Schedule of Investments [Line Items] |  |
Less than 12 months | 495 | 80
12 months or longer | 0 | 0
Total fair value | 495 | 80
Unrealized Losses |  |
Less than 12 months | (12) | (1)
12 months or longer | 0 | 0
Total unrealized losses | (12) | (1)
States and municipalities |  |
Schedule of Investments [Line Items] |  |
Less than 12 months | 107 | 1
12 months or longer | 0 | 0
Total fair value | 107 | 1
Unrealized Losses |  |
Less than 12 months | (1) | 0
12 months or longer | 0 | 0
Total unrealized losses | $ (1) | $ 0

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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=124269663&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=123581744&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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