Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholder's Equity (Deficit) - USD ($) $ in Thousands		Total	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	IPO	IPO Additional Paid-In Capital	Redeemable Convertible Preferred Stock	Redeemable Convertible Preferred Stock IPO	Class A and B Common Stock Common Stock		Class A and B Common Stock IPO Common Stock
Balance at Dec. 31, 2014		$ (124,925)	$ 0	$ (132)	$ (124,793)					$ 0	[1]
Balance (in shares) at Dec. 31, 2014	[1]									11,189,360
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of restricted stock award liability to common stock		88	88
Deemed dividend—preferred stock modification		1,748			1,748			$ (1,748)
Accretion of redeemable convertible preferred stock to redemption value		(9,862)	(4,613)		(5,249)			9,862
Issuance of common stock upon initial public offering, net of offering costs of $4,024						$ 89,069	$ 89,069
Issuance of common stock upon initial public offering, net of offering costs of $4,024 (in shares)	[1]											7,150,000
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering						174,562	174,562		$ (174,562)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering (in shares)									(20,454,489)			20,673,680	[1]
Reclassification of preferred stock warrant liability to equity in connection with initial public offering						1,213	1,213
Stock-based compensation expense		8,375	8,375
Issuance of common stock for equity awards, net of tax withholdings		242	242
Issuance of common stock for equity awards, net of tax witholdings (in shares)	[1]									34,140
Issuance of common stock upon net exercise of warrants (in shares)	[1]									76,565
Issuance of stock for business acquisition		1,500	1,500
Issuance of stock for business acquisition (in shares)	[1]									103,617
Other comprehensive income (loss)		(139)		(139)
Net loss		(36,088)			(36,088)
Balance at Dec. 31, 2015		105,783	270,436	(271)	(164,382)					$ 0	[1]
Balance (in shares) at Dec. 31, 2015	[1]									39,227,362
Balance, redeemable convertible preferred stock at Dec. 31, 2014								$ 166,448
Balance, redeemable convertible preferred stock (in shares) at Dec. 31, 2014								20,454,489
Increase (Decrease) in Temporary Equity [Roll Forward]
Deemed dividend—preferred stock modification		1,748			1,748			$ (1,748)
Accretion of redeemable convertible preferred stock to redemption value		(9,862)	(4,613)		(5,249)			9,862
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering						$ 174,562	$ 174,562		$ (174,562)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering (in shares)									(20,454,489)			20,673,680	[1]
Balance, redeemable convertible preferred stock at Dec. 31, 2015								$ 0
Balance, redeemable convertible preferred stock (in shares) at Dec. 31, 2015								0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Deemed dividend—preferred stock modification								$ 1,748
Stock-based compensation expense		6,606	6,606
Issuance of common stock for contingent consideration payment (in shares)	[1]									207,234
Issuance of common stock for equity awards, net of tax withholdings		5,059	5,059
Issuance of common stock for equity awards, net of tax witholdings (in shares)	[1]									679,801
Issuance of common stock under employee stock purchase plan		3,040
Issuance of stock for business acquisition		500	500
Issuance of stock for business acquisition (in shares)										28,959
Other comprehensive income (loss)		24		24
Net loss		(19,039)			(19,039)
Balance at Sep. 30, 2016		$ 101,973	$ 285,641	$ (247)	$ (183,421)					$ 0	[1]
Balance (in shares) at Sep. 30, 2016	[1]									40,420,571
Increase (Decrease) in Temporary Equity [Roll Forward]
Deemed dividend—preferred stock modification								1,748
Balance, redeemable convertible preferred stock at Sep. 30, 2016								$ 0
Balance, redeemable convertible preferred stock (in shares) at Sep. 30, 2016								0

[1] The activity through June 24, 2015 reflects the sole class of common stock authorized through the closing of the IPO on June 24, 2015, at which point the Company’s certificate of incorporation was amended and restated to authorize Class A and Class B common stock. All capital stock outstanding prior to the IPO was reclassified into Class B common stock and Class A common stock was issued in the IPO.