CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
NET SALES	$ 727,852,000	$ 603,838,000	$ 542,149,000
COST OF SALES	401,599,000	338,813,000	306,368,000
GROSS PROFIT	326,253,000	265,025,000	235,781,000
OPERATING EXPENSES:
Selling, general and administrative	229,134,000	184,398,000	156,348,000
Research and development	51,403,000	45,229,000	40,810,000
Intangible asset impairment charges	809,000	0	0
Contingent consideration expense (benefit)	(298,000)	61,000	80,000
Acquired in-process research and development	12,136,000	461,000	1,000,000
Total operating expenses	293,184,000	230,149,000	198,238,000
INCOME FROM OPERATIONS	33,069,000	34,876,000	37,543,000
OTHER INCOME (EXPENSE):
Interest income	381,000	81,000	272,000
Interest expense	(7,736,000)	(8,798,000)	(6,229,000)
Gain on bargain purchase	11,039,000	0	0
Other income (expense) - net	(872,000)	(773,000)	(386,000)
Other income (expense) — net	2,812,000	(9,490,000)	(6,343,000)
INCOME BEFORE INCOME TAXES	35,881,000	25,386,000	31,200,000
INCOME TAX EXPENSE	8,358,000	5,265,000	7,398,000
NET INCOME	$ 27,523,000	$ 20,121,000	$ 23,802,000
EARNINGS PER COMMON SHARE:
Basic (in dollars per share)	$ 0.56	$ 0.45	$ 0.54
Diluted (in dollars per share)	$ 0.55	$ 0.45	$ 0.53
AVERAGE COMMON SHARES:
Basic (in shares)	48,805	44,408	44,036
Diluted (in shares)	50,101	44,862	44,511