Common Equity and Earnings per Share	3 Months Ended
Mar. 31, 2019
Earnings Per Share [Abstract]
Common Equity and Earnings per Share	(10) Common Equity and Earnings per Share The Company has two classes of common stock: class A common stock and class B common stock. Holders of class A common stock generally have the same rights, including rights to dividends, as holders of class B common stock, except that holders of class A common stock have one vote per share while holders of class B common stock have 10 votes per share. Each share of class B common stock is convertible at any time, at the option of the holder, into one share of class A common stock. As such, basic and fully diluted earnings per share for class A common stock and for class B common stock are the same. The Company has never declared or paid any cash dividends on either class A or class B common stock. As of March 31, 2019 and December 31, 2018, there were no shares of preferred stock issued or outstanding. Potential shares of common stock are included in the diluted earnings per share calculation when dilutive. Potential shares of common stock, consisting of common stock issuable upon exercise of outstanding stock options, are calculated using the treasury stock method. For the three months ended March 31, 2019 and 2018, stock options issued under the 2013 Equity Plan to purchase a weighted average of approximately 1,471,000 and 721,000 shares of class A common stock, respectively, were excluded from the diluted earnings per share calculation because their impact would have been anti-dilutive.

Common Equity and Earnings per Share

3 Months Ended

Mar. 31, 2019

(10) Common Equity and Earnings per Share

The Company has two classes of common stock: class A common stock and class B common stock. Holders of class A common stock generally have the same rights, including rights to dividends, as holders of class B common stock, except that holders of class A common stock have one vote per share while holders of class B common stock have 10 votes per share. Each share of class B common stock is convertible at any time, at the option of the holder, into one share of class A common stock. As such, basic and fully diluted earnings per share for class A common stock and for class B common stock are the same. The Company has never declared or paid any cash dividends on either class A or class B common stock. As of March 31, 2019 and December 31, 2018, there were no shares of preferred stock issued or outstanding.

Potential shares of common stock are included in the diluted earnings per share calculation when dilutive. Potential shares of common stock, consisting of common stock issuable upon exercise of outstanding stock options, are calculated using the treasury stock method.

For the three months ended March 31, 2019 and 2018, stock options issued under the 2013 Equity Plan to purchase a weighted average of approximately 1,471,000 and 721,000 shares of class A common stock, respectively, were excluded from the diluted earnings per share calculation because their impact would have been anti-dilutive.