Stock-Based Compensation (Tables)

6 Months Ended

Nov. 30, 2019

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 November 30,		Six months ended November 30,
	2019	2018	2019	2018
Stock option expense	$0.4	$2.8	$1.0	$3.6
Restricted stock unit expense	0.4	0.7	1.2	1.3
Management stock purchase plan	0.0	0.2	0.0	0.2
Employee stock purchase plan	0.1	0.0	0.2	0.1
Total stock-based compensation expense	$0.9	$3.7	$2.4	$5.2

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 November 30,		Six months ended November 30,
	2019	2018	2019	2018
Common Stock issued pursuant to stock-based compensation plans (in millions)	0.1	0.2	0.1	0.3