Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan

The following table summarizes our stock-based compensation expense (including stock options, restricted stock units ("RSUs") and performance stock units ("PSUs")) for the three months ended March 31, 2022 and 2021:

		Three Months Ended March 31,
(in millions)		2022			2021
Stock option compensation expense	$		2.1	$		1.7
RSU compensation expense			2.1			2.5
PSU compensation expense			0.7			0.6
Total stock-based compensation expense	$		4.9	$		4.8

Schedule of Unrecognized Compensation Cost, Nonvested Awards

The following table summarizes our unrecognized compensation expense and the weighted-average period over which the expense will be recognized as of March 31, 2022:

	March 31, 2022
(in millions, except weighted average years)	Unrecognized Compensation Expense	Weighted Average Years Expense To Be Recognized Over
Stock options	$5.3	2.6
RSUs	$5.4	2.5
PSUs	$9.1	2.1