Condensed Consolidated Statements Of Operations - 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]
Revenue	$ 141,860	$ 132,517	$ 281,977	$ 265,630
Cost of revenue	40,187	36,365	73,882	73,385
Gross profit	101,673	96,152	208,095	192,245
Operating expenses:
Sales and marketing	58,691	59,821	113,196	119,066
Research and development	24,337	16,325	52,083	32,309
General and administrative	22,239	22,101	45,179	44,086
Restructuring	0	1,000	0	8,725
Total operating expenses	105,267	99,247	210,458	204,186
Income (loss) from operations	(3,594)	(3,095)	(2,363)	(11,941)
Other income (expense):
Interest income	2,186	2,665	4,176	4,484
Interest expense	(5,378)	(8,791)	(10,744)	(17,491)
Other, net	(1,105)	(2,250)	(1,702)	(2,206)
Other income (expense), net	(4,297)	(8,376)	(8,270)	(15,213)
Loss before income tax provision	(7,891)	(11,471)	(10,633)	(27,154)
Income tax provision	(914)	(536)	(1,636)	(1,069)
Net loss	$ (8,805)	$ (12,007)	$ (12,269)	$ (28,223)
Net loss per share, basic and diluted (USD per share)	$ (0.15)	$ (0.21)	$ (0.21)	$ (0.49)
Weighted average common shares outstanding, basic and diluted (in shares)	59,715	57,844	59,430	57,635