Borrowings and Subordinated Debt (Components of Long-term Debt and Short-term Borrowings) (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019	Dec. 18, 2019	Dec. 21, 2015
Short-term Debt [Line Items]
Total short-term borrowings	$ 187,000	$ 65,851,000
Total short-term borrowings, weighted average rate	0.30%	1.62%
Debt Instrument [Line Items]
Total long-term debt, amount	$ 261,177,000	$ 190,814,000
Total long-term debt, weighted average rate	1.71%	2.04%
Total short-term and long-term borrowings	$ 261,364,000	$ 256,665,000
Total short-term and long-term borrowings, weighted average rate	1.71%	1.93%
FHLB advances	$ 181,000,000.0
FHLB advances, purchase accounting premiums	202,000
Secured borrowing due in 2022 | Secured borrowing due in 2022
Debt Instrument [Line Items]
Total long-term debt, amount	$ 1,322,000	$ 1,374,000
Total long-term debt, weighted average rate	1.00%	1.00%
Fixed interest rate	1.00%
FHLB Advances | FHLB advances due in 2022 to 2029
Debt Instrument [Line Items]
Total long-term debt, amount	$ 181,202,000	$ 145,000,000
Total long-term debt, weighted average rate	1.09%	1.06%
Unsecured Debt | FRB borrowings
Debt Instrument [Line Items]
Total long-term debt, amount	$ 34,098,000	$ 0
Total long-term debt, weighted average rate	0.35%	0.00%
Fixed interest rate	0.35%
Subordinated notes
Debt Instrument [Line Items]
Fixed interest rate			4.75%	6.375%
Long-term debt gross			$ 30,000,000.0	$ 15,000,000.0
Subordinated notes | Subordinated notes due in 2025 and 2029
Debt Instrument [Line Items]
Total long-term debt, amount	$ 44,555,000	$ 44,440,000
Total long-term debt, weighted average rate	5.29%	5.29%
Minimum | FHLB Advances | FHLB advances due in 2022 to 2029
Debt Instrument [Line Items]
Fixed interest rate	0.42%
Maximum | FHLB Advances | FHLB advances due in 2022 to 2029
Debt Instrument [Line Items]
Fixed interest rate	2.93%
FHLB Advances
Short-term Debt [Line Items]
Total short-term borrowings	$ 0	$ 60,000,000
Total short-term borrowings, weighted average rate	0.00%	1.61%
Securities sold under agreements to repurchase
Short-term Debt [Line Items]
Total short-term borrowings	$ 187,000	$ 851,000
Total short-term borrowings, weighted average rate	0.30%	0.30%
Federal funds purchased
Short-term Debt [Line Items]
Total short-term borrowings	$ 0	$ 5,000,000
Total short-term borrowings, weighted average rate	0.00%	1.90%