Contingencies and Other Accrued Losses - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Increase (decrease) in net income due to restatement effect	$ 18.0	$ (10.8)	$ (7.2)
Litigation settlement amount				$ 6.5

Resulting effect of restatement to correct an error, after tax effects, on the net income of prior periods for the year in which any adjustments are first made. In statements containing more than one period, discloses the effects for each period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22644-107794

Name:	us-gaap_RestatementOfPriorYearIncomeNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration