Investment Securities - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Summary of Investment Holdings [Line Items]
Securities pledged to secure public and other funds, carrying value	$ 8,400,000,000	$ 6,100,000,000
Transfers from available-for-sale to held-to-maturity	127,600,000	148,900,000
Allowance for credit losses for available-for-sale debt securities	$ 0	$ 0
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest
Allowance for securities held-to-maturity	$ (150,000)	$ (150,000)
Accrued interest receivable	$ 50,300,000	50,900,000
Number of securities in security portfolio | security	2,920
Number of securities in unrealized loss position | security	2,588
Equity securities, at fair value	$ 80,372,000	52,507,000
(Losses) gains on equity securities	21,500,000	(4,900,000)	$ 200,000
Downward adjustments on equity securities without readily determinable fair value	0	0	0
Impairments on equity securities without readily determinable fair value	0	0	$ 0
Other Assets
Summary of Investment Holdings [Line Items]
Equity securities without readily determinable fair value	449,300,000	$ 396,800,000
Other Assets | Partnership Interest
Summary of Investment Holdings [Line Items]
Equity securities without readily determinable fair value	252,200,000
Other Assets | Initiatives in Low-to-Moderate Income Neighborhoods
Summary of Investment Holdings [Line Items]
Equity securities without readily determinable fair value	197,100,000
Indiana
Summary of Investment Holdings [Line Items]
Investment securities issued by states and political subdivisions, market value	$ 600,900,000
State and political subdivision investment, equity percentage	10.80%
Percentage of municipal bonds rated A or better	99.60%
Percentage of non rated local interest bonds	0.40%