XML 44 R32.htm IDEA: XBRL DOCUMENT v3.3.1.900
Stock-Based Compensation (Tables)
 6 Months Ended
Nov. 30, 2015
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,
 
2015
 
2014
 
2015
 
2014
Stock option expense
$
3.8

 
$
3.8

 
$
4.4

 
$
4.6

Restricted stock unit expense
0.7

 
0.6

 
1.4

 
1.3

Management stock purchase plan
0.6

 
0.6

 
0.6

 
0.6

Employee stock purchase plan
0.0

 
0.1

 
0.1

 
0.1

Total stock-based compensation expense
$
5.1

 
$
5.1

 
$
6.5

 
$
6.6