Summary of Quarterly Financial Data (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2011	Feb. 28, 2011	Nov. 30, 2010	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Quarterly Financial Data [Line Items]
Sales	$ 91,505	$ 92,924	$ 86,188	$ 90,746	$ 83,638	$ 85,233	$ 74,304	$ 72,266	$ 361,363	$ 315,441	$ 254,274
Cost of sales	80,258	81,470	76,787	78,938	76,321	74,815	67,461	63,009	317,453	281,606	230,820
Gross margin	11,247	11,454	9,401	11,808	7,317	10,418	6,843	9,257	43,910	33,835	23,454
Net income (loss)	$ (4,366)	$ (5,452)	$ (340)	$ 592	$ (3,169)	$ (709)	$ (1,575)	$ 336	$ (9,566)	$ (5,117)	$ 6,683
Earnings (loss) per common share:
Basic	$ (0.35)	$ (0.44)	$ (0.03)	$ 0.05	$ (0.26)	$ (0.06)	$ (0.13)	$ 0.03	$ (0.78)	$ (0.42)
Diluted	$ (0.35)	$ (0.44)	$ (0.03)	$ 0.05	$ (0.26)	$ (0.06)	$ (0.13)	$ 0.03	$ (0.78)	$ (0.42)
Dividends declared