Retirement and Savings Plans - Additional Information (Detail) (USD $)	12 Months Ended							1 Months Ended	3 Months Ended		3 Months Ended		1 Months Ended
	Feb. 28, 2013 CompensationPlan	Feb. 29, 2012	Feb. 28, 2011	Feb. 28, 2013 Equity Securities	Feb. 28, 2013 Fixed Income Securities	Feb. 28, 2013 Maximum	Feb. 28, 2013 Minimum	Nov. 30, 2010 Other Postretirement Benefit Plans, Defined Benefit	Nov. 30, 2010 Other Postretirement Benefit Plans, Defined Benefit	Feb. 28, 2013 Other Postretirement Benefit Plans, Defined Benefit	Nov. 30, 2010 Other Postretirement Benefit Plans, Defined Benefit Prior Fiscal Years	Nov. 30, 2010 Other Postretirement Benefit Plans, Defined Benefit Error Correction	Nov. 30, 2010 Other Postretirement Benefit Plans, Defined Benefit Amendment	Nov. 30, 2010 Other Postretirement Benefit Plans, Defined Benefit Other adjustments	Feb. 28, 2013 Pension Plans, Defined Benefit	Feb. 28, 2013 Pension Plans, Defined Benefit Minimum
Employee Benefit And Retirement Plans [Line Items]
Number of defined contribution retirement plans	1
Maximum participants contribution percentage of annual compensation	85.00%
Defined contribution plan employer matching contribution percentage	6.00%
Saving and investment plan cost	$ 600,000	$ 500,000	$ 500,000
Reduction in expense									400,000		200,000
Reduction in accrued liability	174,000	(280,000)	(1,879,000)					2,400,000				600,000	1,500,000	300,000
Effect of one percentage point increase in estimated discount rate on net pension expense	100,000
Effect of one percentage point increase in estimated discount rate on estimated pension liability	1,500,000
Effect of one percentage point decrease in discount rate on net pension expense	100,000
Effect of one percentage point decrease in discount rate on estimated pension liability	1,800,000
Effect of one percentage point increase or decrease in estimated future return on plan assets on net pension expense	100,000
Estimated future return on plan assets	6.60%
Assumed health care cost annual increases trend						7.00%	5.00%
Effect of a 1% increase in assumed health care cost trend rate on service and interest cost	100,000
Effect of a 1% increase in assumed health care cost trend rate on accumulated postretirement obligation	100,000
Effect of a 1% decrease in assumed health care cost trend rate on service and interest cost	100,000
Effect of a 1% decrease in assumed health care cost trend rate on accumulated postretirement obligation	100,000
Percentage of targeted asset allocation				61.00%	39.00%
Benefit plan expected future contribution in next fiscal year										100,000					3,100,000	1,100,000
Benefit plan additional expected future contribution in next fiscal year															$ 2,000,000