Investment Securities - Securities Pledged (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Realized gains and losses and the proceeds from sales of securities
Amortized cost	$ 677,578	$ 685,728
Debt Securities, Held-to-Maturity, Pledged Status [Extensible Enumeration]	Asset Pledged as Collateral with Right [Member]
Debt Securities, Held-to-Maturity, Pledging Purpose [Extensible Enumeration]	Amortized cost
Asset Pledged as Collateral with Right [Member] | Deposits [Member]
Realized gains and losses and the proceeds from sales of securities
Amortized cost	$ 549,700	555,800
Asset Pledged as Collateral with Right [Member] | Federal Reserve Bank discount window [Member]
Realized gains and losses and the proceeds from sales of securities
Amortized cost	220,900	74,000
Asset Pledged as Collateral with Right [Member] | Federal Reserve Bank Bank Term Funding Program [Member]
Realized gains and losses and the proceeds from sales of securities
Amortized cost	$ 52,600	$ 202,100