Stock-Based Compensation (Tables)

9 Months Ended

Feb. 29, 2012

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

	Three months ended				Nine months ended
	February 29, 2012		February 28, 2011		February 29, 2012		February 28, 2011
Stock option expense	$	1.2	$	1.7	$	6.0	$	7.1
Restricted stock unit expense		1.0		0.9		3.6		3.2
Management stock purchase plan		0.0		0.1		0.2		0.6
Employee stock purchase plan		0.0		0.0		0.2		0.2
Total stock-based compensation expense	$	2.2	$	2.7	$	10.0	$	11.1