Employee Benefit Plans (Details) - Schedule of change in benefit obligations (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Pension Plan, Defined Benefit [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	$ 182.2	$ 173.9
Service cost			0.3
Interest cost	6.9	8.4	8.9
Actuarial losses (gains)	7.4	11.1
Foreign currency translation	(0.8)	(1.9)
Benefits paid, including expenses	(10.1)	(9.3)
Benefit obligation at end of year	185.6	182.2	173.9
Other Postretirement Benefit Plan, Defined Benefit [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	39.6	38.3
Service cost	0	0
Interest cost	1.4	1.7	1.9
Plan participants’ contributions	0.4	0.4
Actuarial losses (gains)	(2.8)	1.7
Benefits paid, including expenses	(2.4)	(2.5)
Benefit obligation at end of year	$ 36.2	$ 39.6	$ 38.3