Weighted Average Assumptions Used to Determine Benefit Obligations and Net Periodic Benefit Cost (Detail)	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Assumptions for benefit obligations:
Assumptions for benefit obligations, discount rate	3.90%	5.00%	4.60%
Assumptions for net periodic benefit cost:
Assumptions for net periodic benefit cost, discount rate	5.00%	4.60%	5.60%
Assumptions for net periodic benefit cost, expected return on plan assets	7.90%	8.00%	8.25%