Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Feb. 29, 2012
Income Taxes [Line Items]
Liability for uncertain tax positions, inclusive of tax, interest, and penalties	$ 2.7
If the accrued liability for uncertain tax positions was de-recognized, the amount that would reduce the effective tax rate	1.8
Tax deductions with uncertain timing	0.7
If the tax benefits with uncertain timing were de-recognized, effect on effective income tax rate	0
Accrued interest related to uncertain tax positions	0.5
Accrued penalties related to uncertain tax positions	0.2
If the accrued interest and penalties related to uncertain tax positions were de-recognized, amount that would reduce effective tax rate	0.3
Effective income tax rate	36.10%
State
Income Taxes [Line Items]
Liability for uncertain tax positions, inclusive of tax, interest, and penalties	2.0
Expected timing of payments to finalize settlements	12
State | Maximum
Income Taxes [Line Items]
Expected payments to finalize settlements	$ 0.5