Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 136,134		$ 142,389		$ 136,109		$ 114,722		$ 117,783		$ 124,871		$ 116,704		$ 103,732		$ 529,354	$ 463,090	$ 468,630
Gross profit	40,628		40,449		37,836		32,549		35,702		36,438		32,970		28,327		151,462	133,437	130,061
Operating income	7,812		10,471		9,976		3,895		7,890		9,534		6,466		2,312		32,154	26,202	26,576
Net income	$ 5,553		$ 8,623		$ 5,841		$ 2,946		$ 2,918		$ 6,850		$ 5,153		$ 1,632		$ 22,963	$ 16,553	$ 19,946
Earnings per share:
Basic (in dollars per share)	$ 0.36	[1]	$ 0.56	[1]	$ 0.39	[1]	$ 0.20	[1]	$ 0.19	[1]	$ 0.46	[1]	$ 0.35	[1]	$ 0.11	[1]	$ 1.51	$ 1.11	$ 1.34
Diluted (in dollars per share)	$ 0.35	[1]	$ 0.55	[1]	$ 0.38	[1]	$ 0.19	[1]	$ 0.19	[1]	$ 0.45	[1]	$ 0.34	[1]	$ 0.11	[1]	$ 1.47	$ 1.10	$ 1.31
Shares used in computing earnings per share:
Basic (in shares)	15,602		15,324		15,098		14,965		15,016		14,984		14,933		14,871		15,248	14,952	14,912
Diluted (in shares)	16,011		15,743		15,419		15,225		15,180		15,099		15,048		15,108		15,601	15,110	15,213

[1] The earnings per common share calculations for each of the quarters were based upon the weighted average number of shares and share equivalents outstanding during each period, and the sum of the quarters may not be equal to the full year earnings per share amounts.