Derivative Instruments and Hedging Activities - Cash Flow Derivatives (Details) - Cash flow hedge - Designated as Hedging Instrument - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Cash Flow Hedging Derivatives
Amount expected to be reclassified from AOCI into earnings	$ (1,455,000)
Interest Rate Swap
Cash Flow Hedging Derivatives
Notional Amount	$ 125,000,000	$ 111,000,000
Weighted Average Pay Rate	1.27%	1.26%
Weighted Average Receive Rate	0.14%	0.22%
Derivative Weighted Average Maturity	4 years 7 days	3 years 11 months 12 days
Net Unrealized Gain (Loss)	$ (683,000)	$ (3,410,000)
Interest Rate Cap
Cash Flow Hedging Derivatives
Notional Amount	95,000,000	95,000,000
Initial premium paid	2,465	$ 2,689,000
Amortization of interest rate cap premiums	$ 212,000
Weighted Average Strike Rate	0.89%
Weighted average maturity	8 years 8 months 23 days