Summary of Significant Accounting Policies - Revenue from Contracts with Customers (Details) $ in Thousands, contract in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) contract	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Summary of Significant Accounting Policies
Number of active contracts | contract	1.1
Transferred at Point in Time
Summary of Significant Accounting Policies
Revenue from contract with customers	$ 237,300	$ 266,800	$ 255,400
Transferred over Time
Summary of Significant Accounting Policies
Revenue from contract with customers	20,900	20,200	19,900
Interchange and debit card transaction fees
Summary of Significant Accounting Policies
Transaction fees	41,300	40,700	38,300
Network costs	20,700	18,500	20,300
Revenue from contract with customers	20,600	22,200	18,000
Trust and investment services income
Summary of Significant Accounting Policies
Revenue from contract with customers	39,447	39,019	36,981
Deposit account services
Summary of Significant Accounting Policies
Revenue from contract with customers	$ 134,600	$ 129,700	$ 107,300