Quarterly Results of Operations (Unaudited) Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 91,092	$ 90,477	$ 91,249	$ 86,631	$ 81,203	$ 73,172	$ 74,948	$ 67,432	$ 359,449	$ 296,755	$ 257,462
Gross profit	42,145	41,054	42,484	39,785	36,358	31,247	32,458	28,435	165,468	128,498	108,802
Income from operations	5,626	6,507	10,847	10,210	5,523	(3,442)	8,777	6,346	32,875	16,788	33,094
Income Tax Expense (Benefit)	806	2,120	3,746	3,159	921	(1,539)	3,124	1,822	9,831	4,328	10,564
Net income	$ 4,970	$ 4,563	$ 6,872	$ 6,639	$ 4,210	$ (1,973)	$ 5,715	$ 4,508	$ 23,044	$ 12,460	$ 22,530
Earnings Per Share, Basic	$ 0.12	$ 0.11	$ 0.19	$ 0.19	$ 0.12	$ (0.06)	$ 0.16	$ 0.13	$ 0.59	$ 0.35	$ 0.64
Earnings Per Share, Diluted	$ 0.12	$ 0.11	$ 0.18	$ 0.18	$ 0.12	$ (0.06)	$ 0.16	$ 0.13	$ 0.58	$ 0.35	$ 0.63