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, 2014	$ 97,243		$ 2	$ 256,388	$ (157,658)	$ (1,489)
Beginning balance, shares at Dec. 31, 2014			26,895,480
Proceeds from follow-on public offering, net of offering costs	127,854		$ 1	127,853
Proceeds from follow-on public offering, net of offering costs, shares			3,450,000
Issuance of common stock under employee equity plans, net of repurchases	1,618			1,618
Issuance of common stock under employee equity plans, net of repurchases, shares			248,240
Vesting of restricted stock	27			27
Stock-based compensation	12,546			12,546
Income tax (deficiencies) benefit from employee stock option exercises	43			43
Shares withheld for tax withholding on vesting of restricted stock units	(2,137)			(2,137)
Components of other comprehensive income (loss), net of tax
Change in unrealized gain (loss) on investments	44					44
Change in unrealized gain (loss) on derivatives	(130)					(130)
Net loss	(20,030)				(20,030)
Comprehensive loss	(20,116)
Ending balance at Mar. 31, 2015	217,078		$ 3	396,338	(177,688)	(1,575)
Ending balance, shares at Mar. 31, 2015			30,593,720
Beginning balance at Dec. 31, 2015	240,201	[1]	$ 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	590			590
Issuance of common stock under employee equity plans, net of repurchases, shares			215,958
Issuance of holdback shares in connection with acquisitions, shares			402,983
Stock-based compensation	15,655			15,655
Income tax (deficiencies) benefit from employee stock option exercises	(4)			(4)
Shares withheld for tax withholding on vesting of restricted stock units	(2,352)			(2,352)
Components of other comprehensive income (loss), net of tax
Change in unrealized gain (loss) on investments	169					169
Change in unrealized gain (loss) on derivatives	916					916
Net loss	(24,007)				(24,007)
Comprehensive loss	(22,922)
Ending balance at Mar. 31, 2016	$ 231,168		$ 3	$ 461,958	$ (230,547)	$ (246)
Ending balance, shares at Mar. 31, 2016			32,259,601

[1] The Condensed Consolidated Balance Sheet as of December 31, 2015 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.