Earnings (Loss) per Share	9 Months Ended
Sep. 30, 2021
Earnings Per Share [Abstract]
Earnings (Loss) per Share	3. Earnings (Loss) per Share Basic earnings (loss) per share is calculated by dividing net income (loss) by the weighted-average number of common shares outstanding during the period, without consideration of potential common shares. Diluted earnings (loss) per share is calculated by dividing net income (loss) by the weighted-average number of common shares outstanding plus potential common shares. Convertible preferred stock and stock options are considered potential common shares and are included in the calculation of diluted earnings (loss) per share using the treasury stock method when their effect is dilutive. Potential common shares are excluded from the calculation of diluted earnings (loss) per share when their effect is anti-dilutive. For the three months ended September 30, 2021, there were 6.7 million of potential common shares that were excluded from the calculation of diluted loss per share because their effect was anti-dilutive. For the nine months ended September 30, 2021, there were 6.7 million potential common shares that were included in the calculation of diluted earnings per share, which consists of: (i) 6.7 million shares of common stock issuable upon conversion of existing convertible preferred stock; and (ii) 9,000 stock options. For the three and nine months ended September 30, 2020, there were 10.0 million of potential common shares that were excluded from the calculation of diluted loss per share because their effect was anti-dilutive.

Earnings (Loss) per Share

9 Months Ended

Sep. 30, 2021

3. Earnings (Loss) per Share

Basic earnings (loss) per share is calculated by dividing net income (loss) by the weighted-average number of common shares outstanding during the period, without consideration of potential common shares. Diluted earnings (loss) per share is calculated by dividing net income (loss) by the weighted-average number of common shares outstanding plus potential common shares. Convertible preferred stock and stock options are considered potential common shares and are included in the calculation of diluted earnings (loss) per share using the treasury stock method when their effect is dilutive. Potential common shares are excluded from the calculation of diluted earnings (loss) per share when their effect is anti-dilutive. For the three months ended September 30, 2021, there were 6.7 million of potential common shares that were excluded from the calculation of diluted loss per share because their effect was anti-dilutive. For the nine months ended September 30, 2021, there were 6.7 million potential common shares that were included in the calculation of diluted earnings per share, which consists of: (i) 6.7 million shares of common stock issuable upon conversion of existing convertible preferred stock; and (ii) 9,000 stock options. For the three and nine months ended September 30, 2020, there were 10.0 million of potential common shares that were excluded from the calculation of diluted loss per share because their effect was anti-dilutive.