Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total		Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2015	$ 240,201		$ 3	$ 448,069	$ (206,540)	$ (1,331)
Beginning balance, shares at Dec. 31, 2015			31,837,144
Issuance of common stock under employee equity plans, net of repurchases	8,106			8,106
Issuance of common stock under employee equity plans, net of repurchases, shares			790,023
Issuance of holdback shares in connection with acquisitions, shares			206,499
Stock-based compensation	42,612			42,612
Income tax deficiencies from employee stock option exercises	(29)			(29)
Shares withheld for tax withholding on vesting of restricted stock units	(6,520)			(6,520)
Components of other comprehensive income (loss), net of tax
Change in unrealized gain (loss) on investments	76					76
Change in unrealized gain (loss) on hedging instruments	486					486
Net income (loss)	(60,461)				(60,461)
Comprehensive income (loss)	(59,899)
Ending balance at Sep. 30, 2016	224,471		$ 3	492,238	(267,001)	(769)
Ending balance, shares at Sep. 30, 2016			32,833,666
Beginning balance at Jun. 30, 2016						(863)
Components of other comprehensive income (loss), net of tax
Change in unrealized gain (loss) on investments	(130)
Change in unrealized gain (loss) on hedging instruments	224
Net income (loss)	(11,738)
Comprehensive income (loss)	(11,644)
Ending balance at Sep. 30, 2016	224,471		$ 3	492,238	(267,001)	(769)
Ending balance, shares at Sep. 30, 2016			32,833,666
Beginning balance at Dec. 31, 2016	231,963	[1]	$ 3	510,257	(276,819)	(1,478)
Beginning balance, shares at Dec. 31, 2016			33,088,990
Cumulative effect of a change in accounting principle	14			2,601	(2,587)
Issuance of common stock under employee equity plans, net of repurchases	17,915			17,915
Issuance of common stock under employee equity plans, net of repurchases, shares			924,350
Stock-based compensation	36,588			36,588
Shares withheld for tax withholding on vesting of restricted stock units	(8,217)			(8,217)
Components of other comprehensive income (loss), net of tax
Change in unrealized gain (loss) on investments	105					105
Change in unrealized gain (loss) on hedging instruments	1,161					1,161
Net income (loss)	19,223				19,223
Comprehensive income (loss)	20,489
Ending balance at Sep. 30, 2017	298,752		$ 3	559,144	(260,183)	(212)
Ending balance, shares at Sep. 30, 2017			34,013,340
Beginning balance at Jun. 30, 2017						720
Components of other comprehensive income (loss), net of tax
Change in unrealized gain (loss) on investments	55
Change in unrealized gain (loss) on hedging instruments	(987)
Net income (loss)	(370)
Comprehensive income (loss)	(1,302)
Ending balance at Sep. 30, 2017	$ 298,752		$ 3	$ 559,144	$ (260,183)	$ (212)
Ending balance, shares at Sep. 30, 2017			34,013,340

[1] The Condensed Consolidated Balance Sheet as of December 31, 2016 has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements.