Net Income (Loss) Per Share (Narrative) (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive effect of outstanding stock options and shares associated with long-term incentive compensation plans	0	179,709
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive effect of outstanding stock options and shares associated with long-term incentive compensation plans	0
Shares not included in the computation of diluted earnings per share	485,108	632,114
Performance Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares not included in the computation of diluted earnings per share	0	117,688