Financial Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	May 31, 2013	Nov. 30, 2012
Fair Value, Inputs, Level 1
Fair Value, Measurement Inputs, Disclosure [Line Items]
Money market funds	$ 57.6
Fair Value, Inputs, Level 2
Fair Value, Measurement Inputs, Disclosure [Line Items]
Long-term debt excluding credit facilities, fair value	296.5	301.2
Long-term debt excluding credit facilities, carrying amount	$ 276.6	$ 276.9