Earnings Per Share

12 Months Ended

Dec. 31, 2023

Earnings per Share

We compute basic and diluted earnings per share using the two-class method, which is an earnings allocation calculation that determines EPS for each class of common stock and participating security. Our vested and exercisable stock options contain non-forfeitable rights to dividends or dividend equivalents and are classified as participating securities in the calculation of EPS. Our unvested stock options, restricted stock units, performance shares and non-employee director awards do not contain nonforfeitable rights to dividends or dividend equivalents and are therefore not classified as participating securities. See "Note 3. Significant Accounting Policies" for more detail of our EPS calculation methodology.

The following table shows the computation of our basic and diluted earnings per common share for the years ended December 31 (in millions, except per share amounts):


	2023		2022		2021
Basic earnings per share:
Net income	$	259.2	$	155.9	$	143.1
Less: Net income allocated to participating securities	(4.9)		—		—
Net income available to common shareholders	$	254.3	$	155.9	$	143.1
Weighted-average shares outstanding - basic	35.7		35.4		35.4
Basic earnings per share	$	7.13	$	4.41	$	4.04

Diluted earnings per share:
Net income	$	259.2	$	155.9	$	143.1
Less: Net income allocated to participating securities	(4.9)		—		—
Net income available to common shareholders	$	254.3	$	155.9	$	143.1
Weighted-average shares outstanding - basic	35.7		35.4		35.4
Effect of dilutive securities:
Equity compensation plans	0.1		0.5		0.6
Weighted-average shares outstanding - diluted *	35.7		35.9		36.0
Diluted earnings per share	$	7.12	$	4.35	$	3.98

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(*) Sum of individual components may not be additive due to rounding.