Stock-Based Compensation

9 Months Ended

Sep. 30, 2021

Share-based Payment Arrangement [Abstract]

The Company's stock-based compensation expense for the three and nine months ended September 30, 2021 and 2020 included PRSUs, non-qualified stock options, RSUs and deferred stock units ("DSUs"). A summary of the Company's stock-based compensation expense is presented in the following table:


	Three Months Ended September 30,				Nine Months Ended September 30,
(in millions)	2021		2020		2021		2020
PRSU expense	$	10.3	$	65.0	$	29.6	$	66.2
Option expense	0.4		1.3		1.2		3.7
RSU/DSU expense	5.4		5.5		15.5		16.7
Total stock-based compensation expense	$	16.1	$	71.8	$	46.3	$	86.6

The Company grants PRSUs to executive officers and certain members of management. Actual payout under the PRSUs is dependent upon the achievement of certain financial goals. During the first quarter of 2021, the Company granted PRSUs as a component of the long-term incentive plan ("2021 PRSUs"). The Company has recorded stock-based compensation expense related to the 2021 PRSUs during the three and nine months ended September 30, 2021, as it was probable that the Company would achieve the specified performance target for the performance period.