Financial Instruments - Additional Information (Detail) (USD $) In Millions	Aug. 31, 2011	Nov. 30, 2010
Fair Value, Inputs, Level 1
Fair Value, Measurement Inputs, Disclosure [Line Items]
Money market funds	$ 69.4
Fair Value, Inputs, Level 2
Fair Value, Measurement Inputs, Disclosure [Line Items]
Long-term debt excluding credit facilities, fair value	266.9	203.6
Long-term debt excluding credit facilities, carrying amount	$ 267.7	$ 204.3