Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Total revenues	$ 126,492	$ 117,399	$ 382,712	$ 389,697
Cost of sales	50,633	47,757	156,747	156,116
Gross profit	75,859	69,642	225,965	233,581
Research and development	11,976	13,103	37,629	39,008
Sales and marketing	26,599	26,504	83,114	82,607
General and administrative	12,146	10,620	38,453	32,652
Acquisition and integration costs	4,456	2,521	9,116	10,923
Total operating expenses	55,177	52,748	168,312	165,190
Operating income	20,682	16,894	57,653	68,391
Interest expense, net	(3,152)	(4,786)	(12,239)	(19,475)
Loss on extinguishment of debt	0	(1,297)	(748)	(8,262)
Total other expense, net	(3,152)	(6,083)	(12,987)	(27,737)
Income before income taxes	17,530	10,811	44,666	40,654
Provision (benefit) for income taxes	1,349	(11)	2,371	(1,050)
Net income	$ 16,181	$ 10,822	$ 42,295	$ 41,704
Basic (loss) earnings per share (in USD per share)	$ 0.39	$ 0.28	$ 1.04	$ 1.11
Diluted (loss) earnings per share (in USD per share)	$ 0.38	$ 0.27	$ 1.02	$ 1.08
Shares used in basic per share calculation (in shares)	41,642	39,290	40,520	37,490
Shares used in diluted per share calculation (in shares)	43,206	42,889	43,051	42,467