Investment Securities - Narrative (Details)	3 Months Ended
	Mar. 31, 2024 USD ($) investment_security	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) investment_security
Summary of Investment Holdings [Line Items]
Net carrying amount of securities transferred from available-for-sale to held-to-maturity	$ 0	$ 360,347,000
Accumulated other comprehensive loss, net of tax	(95,716,000)		$ (99,625,000)
Investments held-to-maturity, allowance for credit losses	115,000		126,000
Allowance for credit losses	0		$ 0
Available-for-sale securities, provision for credit losses	$ 0	0
Available-for-sale and held-to-maturity securities in nonaccrual status | investment_security	0		0
Available-for-sale and held-to-maturity securities purchased with deterioration in credit quality | investment_security	0		0
Available-for-sale and held-to-maturity collateral dependent | investment_security	0		0
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent
Summary of Investment Holdings [Line Items]
Accumulated other comprehensive loss before tax amount	$ (34,000,000)		$ (36,000,000)
Accumulated other comprehensive loss, net of tax	(24,400,000)		(25,800,000)
AOCI, Accumulated Gain (Loss), Debt Securities Transferred To Held-To-Maturity, Available-For-Sale, Parent
Summary of Investment Holdings [Line Items]
Accumulated other comprehensive loss before tax amount	(99,400,000)		(102,900,000)
Accumulated other comprehensive loss, net of tax	(71,300,000)		(73,900,000)
Public deposits, Other Borrowings, and Other Purposes | Asset Pledged as Collateral
Summary of Investment Holdings [Line Items]
Investments at carrying value	2,360,000,000		2,800,000,000
Federal Reserve Discount Window | Asset Pledged as Collateral
Summary of Investment Holdings [Line Items]
Investments at carrying value	2,170,000,000		1,410,000,000
Mortgage-backed securities
Summary of Investment Holdings [Line Items]
Securities transferred from available-for-sale to held-to-maturity		410,700,000
Net carrying amount of securities transferred from available-for-sale to held-to-maturity		360,300,000
Debt securities, held-to-maturity, transfer, unrealized loss		$ (50,400,000)
Investments held-to-maturity, allowance for credit losses	$ 0		$ 0
U.S. Treasury, U.S. Government Agency, and U.S. Government-Sponsored Enterprise Securities
Summary of Investment Holdings [Line Items]
Percentage of total debt securities, available for sale	62.00%