Stock-Based Compensation

9 Months Ended

Feb. 28, 2015

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

Disclosure of Compensation Related Costs, Share-based Payments

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   February 28,				Nine months ended   February 28,
	2015		2014		2015		2014
Stock option expense	$	0.8	$	0.8	$	5.4	$	5.4
Restricted stock unit expense	0.6		0.2		1.9		2.1
Management stock purchase plan	0.1		0.0		0.7		0.1
Employee stock purchase plan	0.1		0.1		0.2		0.2
Total stock-based compensation expense	$	1.6	$	1.1	$	8.2	$	7.8

During the three month periods ended February 28, 2015 and 2014, respectively, approximately 0.1 million and 0.1 million shares of Common Stock were issued by the Corporation pursuant to its stock-based compensation plans. For the nine month periods ended February 28, 2015 and 2014, respectively, approximately 0.6 million and 0.4 million shares of Common Stock were issued by the Corporation pursuant to its stock-based compensation plans.