Net Income (Loss) Per Common Share (Narrative) (Details) - Stock Compensation Plan [Member] - $ / shares	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	680,550	821,025	700,550	791,025
Weighted average price of anti-dilutive options outstanding	$ 22.15	$ 21.71	$ 21.83	$ 22.23
Exercise of stock options excluded		510		4,803

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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