CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Total revenues	$ 225,699	$ 224,211	$ 626,312	$ 635,822
Cost of revenues	77,335	78,191	215,212	228,479
Gross profit	148,364	146,020	411,100	407,343
Operating expenses:
Research and development	90,916	83,611	271,755	236,969
Sales and marketing	37,829	34,408	111,696	98,212
General and administrative	13,039	13,501	38,034	54,933
Total operating expenses	141,784	131,520	421,485	390,114
Income (loss) from operations	6,580	14,500	(10,385)	17,229
Interest expense	(2,016)	(2,195)	(6,005)	(5,408)
Other income, net	956	606	2,466	982
Interest and other, net	(1,060)	(1,589)	(3,539)	(4,426)
Income (loss) before taxes on income	5,520	12,911	(13,924)	12,803
Provision for taxes on income	2,117	874	2,908	3,280
Net income (loss)	$ 3,403	$ 12,037	$ (16,832)	$ 9,523
Net income (loss) per share - basic (in USD per share)	$ 0.07	$ 0.25	$ (0.34)	$ 0.20
Net income (loss) per share - diluted (in USD per share)	$ 0.07	$ 0.24	$ (0.34)	$ 0.19
Shares used in computing net income (loss) per share:
Basic (in shares)	50,587	48,385	49,999	47,883
Diluted (in shares)	51,575	49,494	49,999	49,232