Financial Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Feb. 28, 2013	Nov. 30, 2012
Fair Value, Inputs, Level 1
Fair Value, Measurement Inputs, Disclosure [Line Items]
Money market funds	$ 57.7
Fair Value, Inputs, Level 2
Fair Value, Measurement Inputs, Disclosure [Line Items]
Long-term debt excluding credit facilities, fair value	300.8	301.2
Long-term debt excluding credit facilities, carrying amount	$ 276.8	$ 276.9