CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]
NET SALES	$ 128,865	$ 109,875	$ 248,101	$ 213,823
COST OF SALES	73,241	62,890	140,434	123,845
GROSS PROFIT	55,624	46,985	107,667	89,978
OPERATING EXPENSES:
Selling, general, and administrative	38,599	31,557	75,373	63,685
Research and development	9,641	8,648	18,421	17,756
Total operating expenses	48,240	40,205	93,794	81,441
INCOME FROM OPERATIONS	7,384	6,780	13,873	8,537
OTHER INCOME (EXPENSE):
Interest income	79	74	146	131
Interest (expense)	(2,353)	(1,842)	(4,959)	(3,381)
Other (expense) — net	(28)	(7)	(92)	(70)
Other (expense) — net	(2,302)	(1,775)	(4,905)	(3,320)
INCOME BEFORE INCOME TAXES	5,082	5,005	8,968	5,217
INCOME TAX EXPENSE	1,366	1,253	2,429	794
NET INCOME	$ 3,716	$ 3,752	$ 6,539	$ 4,423
EARNINGS PER COMMON SHARE:
Basic (in dollars per share)	$ 0.09	$ 0.09	$ 0.15	$ 0.10
Diluted (in dollars per share)	$ 0.09	$ 0.09	$ 0.15	$ 0.10
AVERAGE COMMON SHARES:
Basic (in shares)	43,061	42,562	42,963	42,541
Diluted (in shares)	43,310	42,670	43,272	42,753