Borrowings - Short-term Borrowings (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Federal Reserve Bank Borrowings
Short-Term Debt [Line Items]
Pledged collateral	$ 4,900,000	$ 4,900,000
Federal Home Loan Bank Advances
Short-Term Debt [Line Items]
Pledged collateral	754,000	754,000
Repurchase Agreements
Short-Term Debt [Line Items]
Short-term debt	27	2,600
Federal Reserve Bank Borrowings
Short-Term Debt [Line Items]
Available borrowing capacity	3,800,000	3,800,000
Federal Home Loan Bank Advances
Short-Term Debt [Line Items]
Available borrowing capacity	$ 605,500	$ 605,500