Pension Plans and Other Benefits - Changes in Defined Benefit Obligations and Plan Assets (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2010
Amounts recognized in the consolidated balance sheets:
Unfunded pension obligations in noncurrent liabilities	$ (142.2)	$ (117.1)
Amounts recognized in accumulated other comprehensive (income) loss:
Accumulated benefit obligation for the defined benefit pension plans	736.2	686.2
North American Pension Plans [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	694.3	635.5
Service cost	5.6	5.0	3.7
Interest cost	34.5	36.2	37.3
Plan amendments	0	5.8
Actuarial loss (gain)	59.3	28.4
Currency fluctuations	(15.5)	18.4
Employee contribution	0	0
Benefits paid	(34.9)	(35.0)
Benefit obligation at end of year	743.3	694.3	635.5
Change in plan assets:
Fair value at beginning of year	630.0	522.4
Currency fluctuations	(12.9)	14.6
Actual return	45.4	85.6
Company contribution	26.8	42.4
Employee contribution	0	0
Benefits paid	(34.9)	(35.0)
Fair value at end of year	654.4	630.0	522.4
Funded status of the plans at May 31	(88.9)	(64.3)
Amounts recognized in the consolidated balance sheets:
Unfunded pension obligations in current liabilities	(0.6)	(0.7)
Unfunded pension obligations in noncurrent liabilities	(88.3)	(63.6)
Amounts recognized in accumulated other comprehensive (income) loss:
Prior service costs	13.2	15.2
Actuarial (gain)/loss	131.3	99.5
Accumulated benefit obligation for the defined benefit pension plans	54.0	(10.3)	62.1
North American Postretirement Benefit Plans [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	60.1	99.7
Service cost	0.3	0.4	0.7
Interest cost	2.6	3.1	5.5
Plan amendments	0	0
Actuarial loss (gain)	4.0	(38.7)
Currency fluctuations	(0.9)	1.1
Employee contribution	0.1	0.1
Benefits paid	(6.3)	(5.6)
Benefit obligation at end of year	59.9	60.1	99.7
Change in plan assets:
Fair value at beginning of year	0
Currency fluctuations	0	0
Actual return	0	0
Company contribution	6.2	5.5
Employee contribution	0.1	0.1
Benefits paid	(6.3)	(5.6)
Fair value at end of year	0	0
Funded status of the plans at May 31	(59.9)	(60.1)
Amounts recognized in the consolidated balance sheets:
Unfunded pension obligations in current liabilities	(6.3)	(7.0)
Unfunded pension obligations in noncurrent liabilities	(53.6)	(53.1)
Amounts recognized in accumulated other comprehensive (income) loss:
Prior service costs	(4.9)	(6.6)
Actuarial (gain)/loss	(8.9)	(14.5)
Accumulated benefit obligation for the defined benefit pension plans	$ 6.9	$ (35.2)	$ 24.8