Employee Benefit Plans (Details) - Schedule of change in fair value of plan assets (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012
Change in plan assets:
Fair value of plan assets at end of year	$ 173.8	$ 145.8
Pension Plan, Defined Benefit [Member]
Change in plan assets:
Fair value of plan assets at beginning of year	145.8	146.7
Actual return on plan assets	29.9	(0.2)
Employer contributions	8.8	9.9
Benefits paid, including expenses	(10.1)	(9.3)
Foreign currency translation	(0.6)	(1.3)
Fair value of plan assets at end of year	173.8	145.8
Other Postretirement Benefit Plan, Defined Benefit [Member]
Change in plan assets:
Employer contributions	2.0	2.2
Benefits paid, including expenses	(2.4)	(2.6)
Plan participants’ contributions	$ 0.4	$ 0.4