Quarterly Financial Data (Unaudited) - Summary of Quarterly Financial Data (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2013	Aug. 31, 2012	Aug. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Sales	$ 117,427	$ 121,719	$ 110,082	$ 118,022	$ 110,223	$ 111,283	$ 103,477	$ 108,168	$ 467,250	$ 433,151	$ 373,763
Cost of sales	109,830	108,528	99,081	104,764	98,976	99,829	94,076	96,360	422,203	389,241	339,928
Gross margin	7,597	13,191	11,001	13,258	11,247	11,454	9,401	11,808	45,047	43,910	33,835
Net income (loss)	$ (949)	$ 2,058	$ 1,191	$ 1,707	$ (4,366)	$ (5,452)	$ (340)	$ 592	$ 4,007	$ (9,566)	$ (5,117)
Earnings (loss) per common share:
Basic	$ (0.08)	$ 0.17	$ 0.10	$ 0.14	$ (0.35)	$ (0.44)	$ (0.03)	$ 0.05	$ 0.32	$ (0.78)	$ (0.42)
Diluted	$ (0.08)	$ 0.16	$ 0.10	$ 0.14	$ (0.35)	$ (0.44)	$ (0.03)	$ 0.05	$ 0.32	$ (0.78)	$ (0.42)
Dividends declared