Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Revenue		$ 239,866	$ 228,691
Cost of revenue	[1]	120,759	105,161
Gross profit		119,107	123,530
Operating expenses:
Research and development	[1]	38,279	39,627
Sales and marketing	[1]	46,680	43,035
General and administrative	[1]	19,421	21,029
Restructuring and other (Note 11)		4,654	918
Amortization of identified intangibles		12,138	10,778
Total operating expenses		121,172	115,387
Income (loss) from operations		(2,065)	8,143
Interest expense		(4,954)	(4,660)
Interest income and other income, net of expenses		1,289	287
Income (loss) before income taxes		(5,730)	3,770
Benefit from income taxes		2,135	1,017
Net income (loss)		$ (3,595)	$ 4,787
Net income (loss) per basic common share		$ (0.08)	$ 0.10
Net income (loss) per diluted common share		$ (0.08)	$ 0.10
Shares used in basic per-share calculation		45,030	46,551
Shares used in diluted per-share calculation		45,030	47,208

[1] Includes stock-based compensation expense as follows: Three months ended March 31, 2018 2017 Cost of revenue $ 768 $ 834 Research and development 2,355 3,570 Sales and marketing 1,799 2,295 General and administrative 1,848 3,581