Commitments and Contingent Liabilities - Summary of Contract or Notional Amount of Outstanding Loan and Lease Commitments (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Commitments And Contingencies Liabilities [Line Items]
Fixed Rate	$ 86,466	$ 56,576
Variable Rate	1,024,410	973,896
Total	1,110,876	1,030,472
Commitments to Extend Credit
Commitments And Contingencies Liabilities [Line Items]
Fixed Rate	85,886	55,852
Variable Rate	962,547	908,382
Total	1,048,433	964,234
Letters of Credit
Commitments And Contingencies Liabilities [Line Items]
Fixed Rate	580	724
Variable Rate	61,863	65,514
Total	$ 62,443	$ 66,238