Investment Securities - Narrative (Details) shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($) security shares	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) security shares	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Schedule of Investments [Line Items]
Debt securities, available-for-sale, accrued Interest	$ 35.0		$ 35.0		$ 33.0
Debt Securities, held-to-maturity, accrued interest	18.0		18.0		19.0
Write off of accrued interest receivable	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, number of positions | security	389		389
Investment securities available for sale, allowance for credit loss	$ 3.0		$ 3.0
Debt securities, held-to-maturity, threshold period past due	30 days		30 days
Securities past due	$ 10,201.0		$ 10,201.0		10,279.0
Held-to-maturity securities, nonaccrual	0.0		0.0		0.0
Federal Home Loan Bank stock	119.0		119.0		197.0
Nonmarketable equity securities	58.0		58.0		58.0
Amortization method qualified affordable housing project investments	1,810.0		1,810.0		598.0
Provision for credit losses	151.0	42.0	934.0	506.0
Available-for-Sale Securities
Schedule of Investments [Line Items]
Provision for credit losses	(1.0)	$ 0.0	3.0	$ 0.0
Total Past Due
Schedule of Investments [Line Items]
Securities past due	0.0		0.0		0.0
Asset Pledged as Collateral
Schedule of Investments [Line Items]
Investment securities, aggregate carrying value, pledged as collateral	$ 4,030.0		$ 4,030.0		$ 4,200.0
Visa, Inc | Class B Common Stock
Schedule of Investments [Line Items]
Investment owned (in shares) | shares	354		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	345		345
Corporate bonds
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, number of positions | security	44		44