5. Earnings Per Share

The Company reports earnings per share in accordance with ASC Topic 260, “Earnings Per Share,” which establishes standards for computing and presenting earnings per share. Basic earnings per share is computed by dividing net income available to common shareholders by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed by dividing net income available to common shareholders by the weighted-average number of common shares and dilutive common share equivalents then outstanding. Potential common share equivalents consist of restricted stock awards and the incremental common shares issuable upon the exercise of stock options. Under the treasury stock method, unexercised “in-the-money” stock options and warrants are assumed to be exercised at the beginning of the period or at issuance, if later. The assumed proceeds are then used to purchase common shares at the average market price during the period. Share-based payment awards that entitle their holders to receive non-forfeitable dividends before vesting are considered participating securities and are considered in the calculation of basic and diluted earnings per share. There were no such participating securities outstanding during the three-month periods ended March 31, 2018 and 2017.

Basic and diluted weighted average shares outstanding were as follows:


	Three months ended March 31,
	2018		2017
Basic weighted average common shares outstanding		43,621,270		33,891,702
Effect of dilutive securities:
Stock options and restricted stock awards		389,702		490,620
Convertible senior notes		315,760		—

Weighted average common shares, assuming dilution		44,326,732		34,382,322

At March 31, 2018, there were outstanding options to purchase 1,109,353 shares of the Company’s common stock at a weighted average exercise price of $25.34 per share and 703,076 restricted stock units. For the three months ended March 31, 2018, 593,874 options to purchase shares of the Company’s common stock were excluded from the calculation of diluted earnings per share because the exercise prices of the stock options were greater than or equal to the average price of the common shares, and were therefore anti-dilutive.

At March 31, 2017, there were outstanding options to purchase 805,903 shares of the Company’s common stock at a weighted average exercise price of $19.68 per share and 404,781 restricted stock units. For the three months ended March 31, 2017, 458,685 options to purchase shares of the Company’s common stock were excluded from the calculation of diluted earnings per share because the exercise prices of the stock options were greater than or equal to the average price of the common shares, and were therefore anti-dilutive.

As provided by the terms of the indenture underlying the Company’s 2.125% Convertible Senior Notes due 2021 (the “Notes”), the Company has a choice to settle the conversion obligation for the Notes in cash, shares or any combination of the two. The Company currently intends to settle the par value of the Notes in cash and any excess conversion premium in shares. The Company applies the provisions of ASC 260, Earnings Per Share, Subsection 10-45-44, to determine the diluted weighted average shares outstanding as it relates to the conversion spread on its convertible notes. Accordingly, the par value of the Notes will not be included in the calculation of diluted income per share, but the dilutive effect of the conversion premium will be considered in the calculation of diluted net income per share using the treasury stock method. The dilutive impact of the Company’s convertible notes is based on the difference between the Company’s current period average stock price and the conversion price of the convertible notes, provided there is a premium. Pursuant to this accounting standard, there is no dilution from the accreted principal of the Notes as of March 31, 2018 and March 31, 2017.