Basic earnings per share represent net earnings divided by the weighted average number of common shares outstanding for the period. Diluted earnings per share, in addition to the weighted average determined for basic earnings per share, includes potential dilutive common shares using the treasury stock method.

The Company has two classes of issued and outstanding common stock: Class A Common Stock and Class B Common Stock. Holders of Class A Common Stock and holders of Class B Common Stock have substantially identical rights, including rights with respect to any declared dividends or distributions of cash or property and the right to receive proceeds on liquidation or dissolution of the Company after payment of the Company’s indebtedness. The two classes have different voting rights, with holders of Class A Common Stock entitled to one vote per share while holders of Class B Common Stock are entitled to ten votes per share on all matters submitted to a vote of stockholders. The Company uses the two-class method for calculating net earnings per share. Basic and diluted net earnings per share of Class A Common Stock and Class B Common Stock are identical. The shares of Class B Common Stock are convertible at any time at the option of the holder into shares of Class A Common Stock on a share-for-share basis. In addition, shares of Class B Common Stock will be automatically converted into a like number of shares of Class A Common Stock upon transfer to any person or entity who is not a permitted transferee.

The following is a reconciliation of net earnings and weighted average common shares outstanding for purposes of calculating basic earnings per share (in thousands, except per share amounts):

The following is a reconciliation of net earnings and weighted average common shares outstanding for purposes of calculating diluted earnings per share (in thousands, except per share amounts):

There were 195,041 shares excluded from the computation of diluted earnings per share for the three and six months ended June 30, 2018 because they are antidilutive. There were 19,932 and 52,732 shares excluded from the computation of diluted earnings per share for the three and six months ended June 30, 2017 because they are antidilutive.