Long-Term Debt (Credit Facility) (Narrative) (Details) - USD ($)	3 Months Ended	9 Months Ended
	Mar. 31, 2021	Sep. 30, 2021	Mar. 17, 2021	Dec. 31, 2020
Line of Credit Facility [Line Items]
Payments of financing costs	$ 500,000	$ 539,000
Net deferred financing fees		1,521,000		$ 1,151,000
Amortization of deferred financing costs		100,000
PNC Bank [Member]
Line of Credit Facility [Line Items]
Minimum secured borrowing capacity		$ 11,000,000.0
Minimum fixed charge coverage ratio		110.00%
Amended and Restated Prior Credit Agreement [Member] | PNC Bank [Member]
Line of Credit Facility [Line Items]
Debt instrument, expiration date		Mar. 17, 2026
Revolving Credit Facility [Member] | PNC Bank [Member]
Line of Credit Facility [Line Items]
Commitment fee on the daily unused portion of the Revolver		0.25%
Net deferred financing fees		$ 900,000
Revolving Credit Facility [Member] | PNC Bank [Member] | LIBOR [Member]
Line of Credit Facility [Line Items]
Debt instrument, effective interest rate		2.59%
Revolving Credit Facility [Member] | Amended and Restated Prior Credit Agreement [Member] | PNC Bank [Member]
Line of Credit Facility [Line Items]
Maximum secured borrowing capacity			$ 105,000,000.0
Term Loan [Member] | PNC Bank [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Frequency of Periodic Payment		quarterly
Quarterly term loan payments		$ 500,000
Term Loan [Member] | PNC Bank [Member] | LIBOR [Member]
Line of Credit Facility [Line Items]
Debt instrument, effective interest rate		3.09%
Term Loan [Member] | Amended and Restated Prior Credit Agreement [Member] | PNC Bank [Member]
Line of Credit Facility [Line Items]
Maximum secured borrowing capacity			$ 15,000,000.0