Condensed Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Nov. 30, 2012	Nov. 30, 2011
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 1,707	$ 592
Other comprehensive income (loss) net of tax:
Change in fair value of derivatives, net of tax benefit (expense) of $(189) and $168	309	(273)
Loss (gain) from derivative transactions reclassified into earnings, net of tax benefit (expense) of $(1,339) and $(368)	(2,186)	(600)
Amortization of prior service cost, net of taxes of $8	14
Amortization of actuarial loss, net of taxes of $209	341
Other comprehensive loss	(1,522)	(873)
Total comprehensive income (loss)	$ 185	$ (281)