Summary of Significant Accounting Policies - Revenue from Contracts with Customers (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) contract	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Summary of Significant Accounting Policies
Number of active contracts | contract	731,000
Transferred at Point in Time
Summary of Significant Accounting Policies
Revenue from contract with customers	$ 104,300	$ 113,600
Transferred over Time
Summary of Significant Accounting Policies
Revenue from contract with customers	19,000	19,200
Interchange and debit card transaction fees
Summary of Significant Accounting Policies
Revenue from contract with customers	12,600	20,900	$ 26,500
Interchange and debit card transaction fees | Before 606
Summary of Significant Accounting Policies
Transaction fees	24,500	33,000	35,600
Network costs	11,900	12,100	9,100
Trust and investment services income
Summary of Significant Accounting Policies
Revenue from contract with customers	29,244	30,229	$ 25,401
Deposit account services
Summary of Significant Accounting Policies
Revenue from contract with customers	$ 76,400	$ 82,600