Earnings Per Common Share

Basic earnings per common share is calculated by dividing net income by the weighted average number of common shares outstanding during the period. Diluted earnings per common share adjusts basic earnings per common share for the effects of potentially dilutive common shares. Potentially dilutive common shares include the dilutive effects of shares issuable under our equity compensation plans, including stock options and restricted shares, each using the treasury stock method.

Because we expect to settle the principal amount of the outstanding 2.0% convertible senior notes due 2023 ("2023 Convertible Notes") in cash, we use the treasury stock method for calculating the potential dilutive effect of the conversion feature on earnings per common share, if applicable. The conversion feature will have a dilutive impact on earnings per common share when the average market price of our common stock for a given period exceeds the conversion price of $101.38 per share. As we did not meet this threshold during the three months ended March 31, 2019, any shares of common stock potentially issuable upon conversion of the 2023 Convertible Notes are excluded from the calculation of diluted earnings per share.



	Three Months Ended March 31,
	2019		2018
Numerator — basic and diluted
Net income	$	62,645	$	38,945
Denominator
Weighted average number of common shares outstanding — basic	36,981		36,700
Effect of dilutive stock options	431		303
Effect of dilutive restricted shares	807		609
Weighted average number of common shares outstanding — diluted	38,219		37,612
Earnings per common share — basic	$	1.69	$	1.06
Earnings per common share — diluted	$	1.64	$	1.04
Antidilutive stock options and restricted shares	49		613