CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
NET SALES	$ 255,532	$ 224,810	$ 493,881	$ 427,844
COST OF SALES	143,568	124,801	277,281	239,779
GROSS PROFIT	111,964	100,009	216,600	188,065
OPERATING EXPENSES:
Selling, general and administrative	79,977	69,095	158,247	134,007
Research and development	16,332	15,316	32,375	29,638
Intangible asset impairment charge	548	0	548	0
Contingent consideration expense	2,406	178	3,181	219
Acquired in-process research and development	500	306	525	306
Total operating expenses	99,763	84,895	194,876	164,170
INCOME FROM OPERATIONS	12,201	15,114	21,724	23,895
OTHER INCOME (EXPENSE):
Interest income	342	342	698	487
Interest expense	(3,115)	(3,338)	(5,879)	(5,736)
Other expense - net	(429)	(553)	(698)	(721)
Total other expense — net	(3,202)	(3,549)	(5,879)	(5,970)
INCOME BEFORE INCOME TAXES	8,999	11,565	15,845	17,925
INCOME TAX EXPENSE	2,140	624	2,791	1,715
NET INCOME	$ 6,859	$ 10,941	$ 13,054	$ 16,210
EARNINGS PER COMMON SHARE:
Basic (in dollars per share)	$ 0.12	$ 0.22	$ 0.24	$ 0.32
Diluted (in dollars per share)	$ 0.12	$ 0.21	$ 0.23	$ 0.31
AVERAGE COMMON SHARES:
Basic (in shares)	55,017	50,473	54,967	50,376
Diluted (in shares)	56,555	52,154	56,523	52,033