CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Total revenues	$ 857,498	$ 658,140	$ 463,649
Cost of revenues	301,986	189,209	148,672
Gross profit	555,512	468,931	314,977
Operating expenses:
Research and development	322,620	252,175	208,877
Sales and marketing	133,780	97,438	76,860
General and administrative	68,522	44,212	36,431
Total operating expenses	524,922	393,825	322,168
Income (loss) from operations	30,590	75,106	(7,191)
Interest expense	(7,352)	0	0
Other income (loss), net	1,090	(524)	1,449
Interest and other, net	(6,262)	(524)	1,449
Income (loss) before taxes on income	24,328	74,582	(5,742)
Provision for (benefit from) taxes on income	(5,810)	18,312	(18,267)
Net income (loss)	$ 18,518	$ 92,894	$ (24,009)
Net income (loss) per share - basic (in USD per share)	$ 0.38	$ 2.00	$ (0.54)
Net income (loss) per share - diluted (in USD per share)	$ 0.37	$ 1.94	$ (0.54)
Shares used in computing income (loss) per share:
Basic (in shares)	48,145	46,365	44,831
Diluted (in shares)	49,526	47,778	44,831