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 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 year ended December 31, 2018, any shares of common stock potentially issuable upon conversion of the 2023 Convertible Notes are excluded from the calculation of diluted earnings per share.



	Year Ended December 31,
	2018		2017		2016
Numerator — basic and diluted
Net income	$	150,611	$	107,962	$	85,520
Denominator
Weighted average number of common shares outstanding — basic	37,098		38,697		40,943
Effect of dilutive stock options	491		117		281
Effect of dilutive restricted shares	729		378		485
Weighted average number of common shares outstanding — diluted	38,318		39,192		41,709
Earnings per common share — basic	$	4.06	$	2.79	$	2.09
Earnings per common share — diluted	$	3.93	$	2.75	$	2.05
Antidilutive stock options and restricted shares	175		1,561		1,404