(3) Net Income (Loss) Per Common and Common Equivalent Share	6 Months Ended
Jun. 30, 2018
Earnings Per Share [Abstract]
(3) Net Income (Loss) Per Common and Common Equivalent Share	(3) Net Income (Loss) Per Common and Common Equivalent Share Basic net income (loss) per common share is calculated by dividing net income (loss) by the weighted average number of common shares outstanding during the period. Diluted net income (loss) per common share is calculated by dividing net income (loss) by the sum of the weighted average number of common shares plus additional common shares that would have been outstanding if potential dilutive common shares had been issued for granted stock options and stock purchase rights. Common stock equivalents are excluded from the diluted calculations when a net loss is incurred as they would be anti-dilutive.

(3) Net Income (Loss) Per Common and Common Equivalent Share

6 Months Ended

Jun. 30, 2018

(3) Net Income (Loss) Per Common and Common Equivalent Share

Basic net income (loss) per common share is calculated by dividing net income (loss) by the weighted average number of common shares outstanding during the period. Diluted net income (loss) per common share is calculated by dividing net income (loss) by the sum of the weighted average number of common shares plus additional common shares that would have been outstanding if potential dilutive common shares had been issued for granted stock options and stock purchase rights. Common stock equivalents are excluded from the diluted calculations when a net loss is incurred as they would be anti-dilutive.