Long-term Debt - Narrative - Convertible Subordinated Debentures (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Aug. 31, 2014	Nov. 30, 2013
Debt Instrument [Line Items]
Convertible subordinated notes	$ 133.6	$ 193.2
4.0625% Convertible Subordinated Debentures [Member]
Debt Instrument [Line Items]
Principal amount repurchased	59.6
Convertible subordinated notes	$ 133.6	$ 193.2
Convertible debentures into shares of common stock (in shares)	14.8
4.0625% Convertible Subordinated Debentures [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debentures price range	195.00%
4.0625% Convertible Subordinated Debentures [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debentures price range	212.00%