Revolving Credit Facility (Details) - Line of Credit - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Weighted average interest rate	2.88%	2.64%
Allowable indebtedness for acquisition		$ 36,000,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility, borrowing capacity			$ 100,000,000
Line of credit facility, remaining borrowing capacity	$ 87,400,000		66,000,000
Commitment fee	100,000	100,000
Deferred financing costs incurred					$ 600,000
Deferred financing costs net of accumulated amortization	$ 300,000		$ 400,000
Letter of Credit
Line of Credit Facility [Line Items]
Letter of credit		$ 40,000,000		$ 15,000,000
Letter of Credit | Minimum
Line of Credit Facility [Line Items]
Commitment fee percentage	0.15%
Letter of Credit | Maximum
Line of Credit Facility [Line Items]
Commitment fee percentage	0.30%