Investment Securities - Narrative (Details) shares in Thousands, $ in Millions	3 Months Ended
Mar. 31, 2022 USD ($) security shares	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Schedule of Investments [Line Items]
Debt securities, available-for-sale, accrued Interest	$ 26.0		$ 22.0
Debt Securities, held-to-maturity, accrued interest	16.0		7.0
Write off of accrued interest receivable	0.0	$ 0.0
Investment securities, aggregate carrying value, pledged as collateral	$ 5,900.0		5,700.0
Debt securities, held-to-maturity, threshold period past due	30 days
Securities past due	$ 10,074.0		3,809.0
Held-to-maturity securities, nonaccrual	0.0		0.0
Federal Home Loan Bank stock	39.0		40.0
Equity securities without readily determinable fair value, amount	67.0		10.0
Amortization method qualified affordable housing project investments	$ 533.0		$ 156.0
Visa, Inc \| Class B Common Stock
Schedule of Investments [Line Items]
Investment owned (in shares) \| shares	354
Residential Mortgage Backed Securities or Government Agency Securities
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, number of positions \| security	55

Debt Securities, Write Off Of Accrued Interest Receivable

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Amount of investment in qualified affordable housing projects.

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Amount, after allowance for credit loss, of accrued interest on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without an allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount, after allowance for credit loss, of accrued interest on investment in debt security measured at amortized cost (held-to-maturity).

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Amount excluding accrued interest, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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Amount of investment in debt security measured at amortized cost (held-to-maturity) on nonaccrual status.

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Threshold period for when investment in debt security measured at amortized cost (held-to-maturity) is considered past due, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Excludes threshold period past due to write off as uncollectible.

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Amount of investment in equity security without readily determinable fair value.

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Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

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Balance held at close of period in number of shares.

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Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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