Securities Available for Sale and Held to Maturity - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Reclassification of Securities available for sale to securities held to maturity		$ 766,000,000
Net unrealized holding loss on AFS Securities at date of transfer		(91,900,000)
Net unrealized holding losses on AFS Securities, net of tax at date of transfer		(68,900,000)
Net unamortized, unrealized loss on transfer of securities	$ (57,600,000)	(69,200,000)
Credit loss recognized	0	0
Potential credit loss exposure	340,000	4,500,000
Securities held to maturity	1,426,279,000	1,494,514,000
Pledged to collateralize public deposits and securities sold under repurchase agreements and for other purposes as permitted by law	2,321,000,000	2,693,000,000
Pledged securities providing additional contingency funding	0	0
30 Days or More Past Due [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities held to maturity	0	0
Securities Available for Sale [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Accrued interest receivable	3,700,000	4,000,000
Securities Held to Maturity [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Accrued interest receivable	2,600,000	2,700,000
Reserve for credit loss	0	0
Held-to-maturity nonnaccrual	$ 0	$ 0