Stock-Based Compensation

6 Months Ended

Nov. 30, 2011

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

10. 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,
	2011		2010		2011		2010
Stock option expense	$	3.4	$	1.6	$	4.8	$	5.4
Restricted stock unit expense		2.0		0.9		2.6		2.3
Management stock purchase plan		0.2		0.5		0.2		0.5
Employee stock purchase plan		0.1		0.1		0.2		0.2
Total stock-based compensation expense	$	5.7	$	3.1	$	7.8	$	8.4

During each of the three and six-month periods ended November 30, 2011 and 2010, shares of Common Stock issued by the Corporation pursuant to its stock-based compensation plans were not material.