Stock-Based Compensation (Tables)

3 Months Ended

Aug. 31, 2021

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 stock-based compensation expense included in Selling, general and administrative expenses for the periods indicated: 

	Three months ended
	August 31,		August 31,
	2021		2020
Stock option expense	$	0.7	$	0.3
Restricted stock unit expense		0.7		0.2
Management stock purchase plan		0.0		—
Employee stock purchase plan		0.1		0.1
Total stock-based compensation expense	$	1.5	$	0.6

Schedule of Shares Issued Pursuant to Share-based Compensation Activity

The following table sets forth Common Stock issued pursuant to stock-based compensation plans for the periods indicated:

	Three months ended
	August 31,	August 31,
	2021	2020
Common Stock issued pursuant to stock-based compensation plans (in millions)	0.1	0.0