Asset Acquired and Liabilities Assumed on Acquisition (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	May 31, 2012	May 31, 2011
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Business acquisition cash acquired	$ 12.3	$ 0.8

The amount of cash and cash equivalents acquired in a business combination.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsCashAndCashEquivalents
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant