Fair Value Measurements - Fair Value of Assets and Liabilities Measured on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Aug. 31, 2012	May 31, 2012
Assets:
Total assets, Fair Value	$ 637.2	$ 454.8
Liabilities:
Total liabilities, Fair Value	80.5	76.4
Money market funds [Member]
Assets:
Total assets, Fair Value	481.7	303.1
Time deposit [Member]
Assets:
Total assets, Fair Value	36.4	36.3
Greek bonds [Member]
Assets:
Total assets, Fair Value	7.0	6.3
Pension plan assets [Member]
Assets:
Total assets, Fair Value	111.6	108.7
Foreign currency exchange contracts [Member]
Assets:
Total assets, Fair Value	0.1	0.2
Liabilities:
Total liabilities, Fair Value	0.1	0.2
Other [Member]
Assets:
Total assets, Fair Value	0.4	0.2
Interest rate swaps [Member]
Liabilities:
Total liabilities, Fair Value	80.4	76.2
Level 1 [Member]
Assets:
Total assets, Fair Value	481.9	303.1
Level 1 [Member] | Money market funds [Member]
Assets:
Total assets, Fair Value	481.7	303.1
Level 1 [Member] | Other [Member]
Assets:
Total assets, Fair Value	0.2
Level 2 [Member]
Assets:
Total assets, Fair Value	155.1	151.5
Liabilities:
Total liabilities, Fair Value	80.5	76.4
Level 2 [Member] | Time deposit [Member]
Assets:
Total assets, Fair Value	36.4	36.3
Level 2 [Member] | Greek bonds [Member]
Assets:
Total assets, Fair Value	7.0	6.3
Level 2 [Member] | Pension plan assets [Member]
Assets:
Total assets, Fair Value	111.6	108.7
Level 2 [Member] | Foreign currency exchange contracts [Member]
Assets:
Total assets, Fair Value	0.1	0.2
Liabilities:
Total liabilities, Fair Value	0.1	0.2
Level 2 [Member] | Interest rate swaps [Member]
Liabilities:
Total liabilities, Fair Value	80.4	76.2
Level 3 [Member]
Assets:
Total assets, Fair Value	0.2	0.2
Level 3 [Member] | Other [Member]
Assets:
Total assets, Fair Value	$ 0.2	$ 0.2