Derivative Instruments and Hedge Activities - Summary of Derivative Financial Instruments and Classification on Consolidated Statements of Financial Condition (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Derivatives Fair Value [Line Items]
Notional Amount	$ 382,435,000	$ 341,358,000
Other Assets	19,133,000	7,960,000
Other Liabilities	20,327,000	8,519,000
Other Interest Rate Derivatives
Derivatives Fair Value [Line Items]
Notional Amount	373,782,000
Other Assets	19,133,000
Other Liabilities	20,307,000
Derivatives Not Designated As Hedging Instruments | Other Credit Derivatives
Derivatives Fair Value [Line Items]
Notional Amount	8,653,000	9,302,000
Other Liabilities	20,000	12,000
Derivatives Not Designated As Hedging Instruments | Other Interest Rate Derivatives
Derivatives Fair Value [Line Items]
Notional Amount	373,782,000	332,056,000
Other Assets	19,133,000	7,960,000
Other Liabilities	$ 20,307,000	$ 8,507,000