CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenues	$ 121,116	$ 114,830	$ 303,358	$ 317,628
Costs and expenses:
Cost of revenues	73,603	70,458	185,445	191,387
Sales and marketing	24,555	24,310	73,403	73,703
Research and development	9,744	9,236	28,958	28,305
General and administrative	12,099	17,643	39,457	44,101
Change in fair value of contingent consideration	1,562	999	5,788	1,052
Total costs and expenses	121,563	122,646	333,051	338,548
Loss from operations	(447)	(7,816)	(29,693)	(20,920)
Interest expense	(3,646)	(3,507)	(10,830)	(10,416)
Other income (expense), net	(59)	1,175	708	4,214
Loss before income taxes	(4,152)	(10,148)	(39,815)	(27,122)
Provision for income taxes	66	215	261	375
Net loss	$ (4,218)	$ (10,363)	$ (40,076)	$ (27,497)
Net loss per share, basic and diluted (in USD per share)	$ (0.05)	$ (0.12)	$ (0.44)	$ (0.30)
Weighted-average number of common shares used in computing net loss per share, basic and diluted (in shares)	90,585	88,789	90,113	91,850