Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

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, 2020 and 2019:

	Three Months Ended March 31,
(in millions)	2020			2019
Stock option compensation expense	$	0.8		$	0.5
RSU compensation expense	1.0			1.0
PSU compensation expense	(0.9		)	0.5
Total stock-based compensation expense	$	0.9		$	2.0

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, 2020:

	March 31, 2020
	Unrecognized	Weighted Average
	Compensation	Years Expense To Be
(in millions, except weighted average years)	Expense	Recognized Over
Stock options	$6.9	2.4
RSUs	$9.3	2.3
PSUs	$3.2	2.5