Investment Securities Available for Sale - Narrative (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2023 USD ($) security	Dec. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Financing Receivable, Impaired [Line Items]
Securities in a loss position for less than twelve months | security	12	12
Investment securities in a loss position for twelve months or longer | security	343	343
Proceeds from sales of investment securities available for sale	$ 1,300,000,000	$ 1,301,520,000	$ 0	$ 565,400,000
Debt securities, available-for-sale, realized loss	77,700,000	81,859,000	0	1,990,000
Payments to acquire investment securities available for sale	1,280,000,000	2,150,430,000	2,287,318,000	$ 6,877,712,000
Allowance for credit loss	0	0
Collateral Pledged
Financing Receivable, Impaired [Line Items]
Pledged to secure deposits	$ 5,190,000,000	$ 5,190,000,000	$ 4,470,000,000