Condensed Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2013	May 31, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 2,058	$ (5,452)	$ 4,956	$ (5,200)
Other comprehensive income (loss) net of tax:
Change in fair value of derivatives, net of tax benefit (expense) of $10, $408, $(147), and $272, respectively	(17)	(667)	239	(444)
Gain from derivative transactions reclassified into earnings, net of tax expense of $(92), $(14), $(1526), and $(586), respectively	(149)	(22)	(2,490)	(957)
Amortization of prior service cost, net of taxes of $8, $0, $25, and $0, respectively	13		41
Amortization of actuarial loss, net of taxes of $209, $0, $627, and $0, respectively	341		1,023
Other comprehensive income (loss)	188	(689)	(1,187)	(1,401)
Total comprehensive income (loss)	$ 2,246	$ (6,141)	$ 3,769	$ (6,601)