Quarterly Financial Data - Schedule of Quarterly Financial Data (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of quarterly financial data
Net sales	$ 108,545	$ 133,072	$ 152,747	$ 153,293	$ 132,894	$ 140,973	$ 155,955	$ 134,163	$ 547,657	$ 563,985	$ 450,745
Gross profit	2,143	10,092	16,570	16,073	3,048	11,273	16,220	13,429	44,878	43,970	32,827
Net income	$ 657	$ 4,981	$ 7,321	$ 7,265	$ 5,613	$ 6,916	$ 9,719	$ 7,963	$ 20,224	$ 30,211	$ 12,014
Basic and diluted net income per share	$ 0.05	$ 0.41	$ 0.60	$ 0.60	$ 0.46	$ 0.57	$ 0.80	$ 0.66	$ 1.67	$ 2.50	$ 0.99