Stock-Based Compensation

6 Months Ended

Nov. 30, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

STOCK-BASED COMPENSATION

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,
	2018		2017		2018		2017
Stock option expense	$	2.8	$	4.6	$	3.6	$	5.4
Restricted stock unit expense	0.7		0.8		1.3		1.4
Management stock purchase plan	0.2		0.6		0.2		0.6
Employee stock purchase plan	0.0		0.0		0.1		0.1
Total stock-based compensation expense	$	3.7	$	6.0	$	5.2	$	7.5

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,
	2018	2017	2018	2017
Common Stock issued pursuant to stock-based compensation plans (in millions)	0.2	0.1	0.3	0.2