Stock-Based Compensation (Tables)

3 Months Ended

Aug. 31, 2011

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]

	Three months ended August 31,
	2011		2010
Stock option expense	$	1.5	$	3.8
Restricted stock unit expense		0.7		1.4
Management stock purchase plan expense		0.0		0.0
Employee stock purchase plan expense		0.0		0.1
Total stock-based compensation expense	$	2.2	$	5.3