Stock-Based Compensation (Tables)

9 Months Ended

Feb. 29, 2020

Disclosure of Compensation Related Costs, Share-based Payments [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		Nine months ended
	February 29,	February 28,	February 29,	February 28,
	2020	2019	2020	2019
Stock option expense	$0.4	$0.7	$1.4	$4.3
Restricted stock unit expense	0.3	0.7	1.5	2.0
Management stock purchase plan	0.0	0.0	0.0	0.2
Employee stock purchase plan	0.0	0.2	0.2	0.3
Total stock-based compensation expense	$0.7	$1.6	$3.1	$6.8

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		Nine months ended
	February 29,	February 28,	February 29,	February 28,
	2020	2019	2020	2019
Common Stock issued pursuant to stock-based compensation plans (in millions)	0.0	0.1	0.1	0.4