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Securities - Narrative (Details) | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2022 USD ($) security | Mar. 31, 2022 USD ($) | Sep. 30, 2021 USD ($) | Sep. 30, 2022 USD ($) security | Sep. 30, 2021 USD ($) | Dec. 31, 2021 USD ($) security
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |  |  |  |  |
Fair value of debt securities from AFS to HTM |  | $ 3,010,000,000.00 |  |  |  |
Unrealized losses, net of tax, from transfer of AFS to HTM |  | $ 113,000,000 |  |  |  |
AFS and HTM, accrued interest | $ 33,800,000 |  |  | $ 33,800,000 |  | $ 33,100,000
Available-for-sale debt securities fair value, Total | $ 5,768,304,000 |  |  | $ 5,768,304,000 |  | $ 7,711,952,000
Number of available-for-sale debt securities in an unrealized loss position | security | 557 |  |  | 557 |  | 431
Debt Securities, AFS, allowance for credit loss | $ 0 |  |  | $ 0 |  | $ 0
Provision (reversal of provision) for credit losses | 0 |  | $ 0 | 0 | $ 0 |
HTM securities allowance for credit loss | 0 |  |  | 0 |  |
AFS and HTM debt securities carrying value | 9,784,021,000 |  |  | 9,784,021,000 |  |
Asset Pledged as Collateral |  |  |  |  |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |  |  |  |  |
AFS and HTM debt securities carrying value | $ 1,220,000,000 |  |  | $ 1,220,000,000 |  | $ 803,900,000
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities |  |  |  |  |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |  |  |  |  |
Number of available-for-sale debt securities in an unrealized loss position | security | 262 |  |  | 262 |  | 180
Non-agency mortgage-backed securities |  |  |  |  |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |  |  |  |  |
Number of available-for-sale debt securities in an unrealized loss position | security | 100 |  |  | 100 |  |
Corporate debt securities |  |  |  |  |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |  |  |  |  |
Available-for-sale debt securities fair value, Total | $ 529,565,000 |  |  | $ 529,565,000 |  | $ 435,410,000
Number of available-for-sale debt securities in an unrealized loss position | security | 68 |  |  | 68 |  | 30
U.S. government-sponsored enterprises debt securities |  |  |  |  |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |  |  |  |  |
Available-for-sale debt securities fair value, Total | $ 260,424,000 |  |  | $ 260,424,000 |  | $ 1,176,554,000
Number of available-for-sale debt securities in an unrealized loss position | security |  |  |  |  |  | 50
U.S. Treasury securities |  |  |  |  |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |  |  |  |  |
Available-for-sale debt securities fair value, Total | $ 600,677,000 |  |  | $ 600,677,000 |  | $ 983,657,000
Number of available-for-sale debt securities in an unrealized loss position | security |  |  |  |  |  | 21

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