Stock Based Compensation (Tables)

6 Months Ended

Jun. 30, 2021

Share-based Payment Arrangement [Abstract]

Summary of Stock Based Compensation Activity

The following table shows a summary of RSU activity during the three and six months ended June 30, 2021 and 2020:

	Three Months Ended June 30,				Six Months Ended June 30,
	2021		2020		2021		2020
RSU compensation expense	$	8.1	$	7.3	$	14.7	$	13.6
Income tax benefit	(1.5)		(1.3)		(2.7)		(2.4)
RSU compensation expense, net of tax	$	6.6	$	6.0	$	12.0	$	11.2
RSUs granted	29,798		33,538		198,393		261,950
Weighted average grant date fair value per unit	$	139.58	$	100.62	$	139.08	$	90.99
Total fair value of vested RSUs	$	2.3	$	15.5	$	32.3	$	24.4

The following table shows a summary of PSU activity during the three and six months ended June 30, 2021 and 2020:

	Three Months Ended June 30,				Six Months Ended June 30,
	2021		2020		2021		2020
PSU compensation expense	$	8.6	$	7.3	$	14.8	$	12.1
Income tax benefit	(1.2)		(0.8)		(1.8)		(1.3)
PSU compensation expense, net of tax	$	7.4	$	6.5	$	13.0	$	10.8
PSUs granted	6,578		—		208,040		302,274
Weighted average grant date fair value per unit	$	148.04	$	—	$	148.04	$	87.36
Total fair value of vested PSUs	$	—	$	—	$	22.5	$	24.4