Summary of Long-Term Debt (Parenthetical) (Detail)	Aug. 31, 2011 5.4 percent Senior Notes	Nov. 30, 2010 5.4 percent Senior Notes	Aug. 31, 2011 4.6 percent Senior Notes	Jan. 31, 2011 4.6 percent Senior Notes	Aug. 31, 2011 4.8 percent Revenue Bonds	Nov. 30, 2010 4.8 percent Revenue Bonds	Aug. 31, 2011 6.8 percent Revenue Bonds	Nov. 30, 2010 6.8 percent Revenue Bonds	Aug. 31, 2011 6.3 percent Term Loan	Nov. 30, 2010 6.3 percent Term Loan
Debt Instrument [Line Items]
Debt, interest rate	5.40%	5.40%	4.60%	4.60%	4.80%	4.80%	6.80%	6.80%	6.30%	6.30%