Investment Securities - Narrative (Details) shares in Thousands, $ in Millions	3 Months Ended
Mar. 31, 2023 USD ($) security shares	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Schedule of Investments [Line Items]
Debt securities, available-for-sale, accrued Interest	$ 30.0		$ 33.0
Debt Securities, held-to-maturity, accrued interest	17.0		19.0
Write off of accrued interest receivable	$ 0.0	$ 0.0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, number of positions \| security	337
Investment securities available for sale, allowance for credit loss	$ 4.0
Debt securities, held-to-maturity, threshold period past due	30 days
Securities past due	$ 10,381.0		10,279.0
Held-to-maturity securities, nonaccrual	0.0		0.0
Federal Home Loan Bank stock	393.0		197.0
Nonmarketable equity securities	62.0		58.0
Amortization method qualified affordable housing project investments	1,660.0		598.0
Total Past Due
Schedule of Investments [Line Items]
Securities past due	0.0		0.0
Asset Pledged as Collateral
Schedule of Investments [Line Items]
Investment securities, aggregate carrying value, pledged as collateral	$ 4,160.0		$ 4,200.0
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	315
Corporate bonds
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, number of positions \| security	22

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