CONSOLIDATED STATEMENT OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock Private Placement [Member]	Common Stock Follow On Public Offering [Member]	Common Stock	Additional Paid-In Capital Private Placement [Member]	Additional Paid-In Capital Follow On Public Offering [Member]	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Private Placement [Member]	Follow On Public Offering [Member]	Total
Balance at Dec. 31, 2013											$ 23,000
Balance (in shares) at Dec. 31, 2013											20,890,000
Increase (Decrease) in Temporary Equity
Issuance of convertible preferred stock, net of issuance costs											$ 11,623
Issuance of convertible preferred stock (in shares)											6,451,057
Accretion of convertible preferred stock to redemption value											$ 2,054
Balance at Dec. 31, 2014											$ 36,677
Balance (in shares) at Dec. 31, 2014											27,341,057
Balance at Dec. 31, 2013							$ 3	$ (9,166)			$ (9,163)
Balance (in shares) at Dec. 31, 2013			2,730,427
Increase (Decrease) in Stockholders' Equity
Unrealized gain (loss) on marketable securities, net of tax of $0							(9)				(9)
Equity Impact of Purchase Put Option								(1,039)			(1,039)
Stock-based compensation expense						$ 27					27
Accretion of convertible preferred stock, APIC effect						(27)
Accretion of convertible preferred stock, equity effect								(2,027)			(2,054)
Net loss								(8,517)			(8,517)
Balance at Dec. 31, 2014							(6)	(20,749)			(20,755)
Balance (in shares) at Dec. 31, 2014			2,730,427
Increase (Decrease) in Temporary Equity
Issuance of convertible preferred stock, net of issuance costs											$ 39,864
Issuance of convertible preferred stock (in shares)											12,944,984
Accretion of convertible preferred stock to redemption value											$ 1,764
Issuance of common stock upon conversion of convertible preferred stock											$ (78,305)
Conversion of convertible preferred stock into permanent equity (in shares)											(40,286,041)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock						56,550					$ 56,550
Number of shares issued			5,750,000
Issuance of stock upon conversion						78,305					78,305
Issuance of stock upon conversion, shares			11,677,076
Unrealized gain (loss) on marketable securities, net of tax of $0							(148)				(148)
Foreign currency translation adjustment							5				5
Stock-based compensation expense						891					891
Accretion of convertible preferred stock, APIC effect						(243)
Accretion of convertible preferred stock, equity effect								(1,521)			(1,764)
Net loss								(20,563)			(20,563)
Balance at Dec. 31, 2015						135,503	(149)	(42,833)			$ 92,521
Balance (in shares) at Dec. 31, 2015			20,157,503								20,157,503
Increase (Decrease) in Stockholders' Equity
Issuance of common stock in connection with Vixen acquisition						2,355					$ 2,355
Issuance of common stock in connection with Vixen acquisition, shares			159,420
Issuance of common stock				$ 18,547	$ 98,158				$ 18,547	$ 98,158
Number of shares issued	1,081,082	4,600,000
Exercise of stock options and vesting of RSUs						4					$ 4
Exercise of stock options and vesting of RSUs, shares			61,176								51,980
Unrealized gain (loss) on marketable securities, net of tax of $0							105				$ 105
Foreign currency translation adjustment							(225)				(225)
Stock-based compensation expense						6,104					6,104
Net loss								(48,079)			(48,079)
Balance at Dec. 31, 2016						$ 260,671	$ (269)	$ (90,912)			$ 169,490
Balance (in shares) at Dec. 31, 2016			26,059,181								26,059,181