Pensions and Other Postretirement Benefits - Components of Accumulated Other Comprehensive Loss Unrecognized (Detail) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2013	Aug. 31, 2012
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized prior service cost (credit)	$ 1,288	$ 1,529
Unrecognized net actuarial loss	10,091	22,976
Total	11,379	24,505
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized prior service cost (credit)	(155)	(307)
Unrecognized net actuarial loss	(318)	3,594
Total	$ (473)	$ 3,287