Earnings Per Share Earnings Per Share (Policies)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Earnings Per Share, Policy [Policy Text Block]

Basic and diluted earnings per share are based on the weighted-average number of shares of common stock and potential common stock outstanding during the period. Potential common stock, for purposes of determining diluted earnings per share, includes the effects of dilutive restricted stock units, stock options and convertible securities. The effect of such potential common stock is computed using the treasury stock method or the if-converted method, as applicable.