Earnings per Common Share

12 Months Ended

Dec. 31, 2020

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 (restricted share awards, restricted stock units and performance stock units), 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 had a dilutive impact on earnings per common share for the years ended December 31, 2020 and 2019, as the average market price per share of our common stock for the periods exceeded the conversion price of $101.38 per share. See Note 14, "Debt" for additional information about the 2023 Convertible Notes.


	Year Ended December 31,
	2020		2019		2018
Numerator — basic and diluted
Net income	$	210,682	$	216,726	$	150,611
Denominator
Weighted average number of common shares outstanding — basic	35,602		36,774		37,098
Effect of dilutive restricted shares	763		820		729
Effect of dilutive stock options	419		455		491
Effect of dilutive convertible notes	365		62		—
Weighted average number of common shares outstanding — diluted	37,149		38,111		38,318
Earnings per common share — basic	$	5.92	$	5.89	$	4.06
Earnings per common share — diluted	$	5.67	$	5.69	$	3.93
Antidilutive stock options and restricted shares	66		19		175