Long-Term Debt - Carrying Amounts of Liability and Equity Components (Detail) (USD $) In Millions, unless otherwise specified	May 31, 2013	Nov. 30, 2012	Nov. 30, 2011
Proforma Debt Instrument [Line Items]
Carrying amount of equity component, net of equity issuance costs		$ 44.1
Principal amount of 2 1/4% Debentures	200.2	200.2	200.2
Unamortized debt discount
Carrying amount of liability component		0.2
Convertible subordinated debentures, bearing interest at 2.25% maturing in November 2024 [Member]
Proforma Debt Instrument [Line Items]
Principal amount of 2 1/4% Debentures	$ 0.2	$ 0.2	$ 0.2

Carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Convertible Notes Payable, excluding current portion. Convertible Notes Payable is a written promise to pay a note which can be exchanged for a specified amount of another, related security, at the option of the issuer and the holder.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_ConvertibleLongTermNotesPayable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant