Earnings per Common Share

9 Months Ended

Sep. 30, 2021

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 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 had a dilutive impact on earnings per common share for the three and nine months ended September 30, 2021 and 2020, 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 9, "Debt" for additional information about the 2023 Convertible Notes.


	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
Numerator — basic and diluted
Net income	$	69,480	$	50,172	$	196,758	$	155,093
Denominator
Weighted average number of common shares outstanding — basic	33,495		35,639		33,478		36,073
Effect of dilutive restricted shares	662		708		697		774
Effect of dilutive stock options	363		402		369		436
Effect of dilutive convertible notes	842		337		721		425
Weighted average number of common shares outstanding — diluted	35,362		37,086		35,265		37,708
Earnings per common share — basic	$	2.07	$	1.41	$	5.88	$	4.30
Earnings per common share — diluted	$	1.96	$	1.35	$	5.58	$	4.11
Antidilutive stock options and restricted shares	2		83		5		50