Earnings per share (Tables)

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Schedule of Net Income Per Share, Basic and Diluted

The following table presents the calculation of basic and diluted net income per share:

	Year Ended December 31,
(in millions, except per share data)	2021		2020		2019
Numerator:
Net income	$	230.9	$	305.1	$	54.5
Denominator:
Weighted-average number of shares-basic	53.5		52.7		51.5
Dilutive effect of employee incentive plans	0.6		1.1		0.9
Weighted-average number of shares-diluted	54.1		53.8		52.4
Net income per share-basic	$	4.32	$	5.79	$	1.06
Net income per share-diluted	$	4.27	5.67		$	1.04

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

The following table presents the share-based awards that are not considered in the diluted net income per share calculation generally because the exercise price of the awards was greater than the average per share closing price during the year ending December 31, 2021, 2020 and 2019. In certain instances awards may be anti-dilutive even if the average market price exceeds the exercise price when the sum of the assumed proceeds exceeds the difference between the market price and the exercise price.

	Year Ended December 31,
	2021	2020	2019
Anti-dilutive stock awards	1.0	—	$	0.9