Capitalization - Additional Information (Detail) $ / shares in Units, $ in Thousands				12 Months Ended
	May 15, 2015 USD ($) $ / shares shares	Jan. 13, 2015 USD ($) $ / shares shares	Sep. 16, 2014	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares
Schedule of Capitalization [Line Items]
Common stock, shares authorized | shares				100,000,000	100,000,000
Common stock, par value | $ / shares				$ 0.0001	$ 0.0001
Preferred stock, shares authorized | shares				10,000,000	10,000,000
Preferred stock, par value | $ / shares				$ 0.0001	$ 0.0001
Convertible preferred stock, issuance cost				$ 60
Net gain on extinguishment of convertible preferred stock					$ 759
Closing date of IPO				Sep. 22, 2015
Outstanding convertible preferred stock into common stock | shares				16,298,045
Series C Convertible Preferred Stock [Member]
Schedule of Capitalization [Line Items]
Convertible preferred stock, shares sale and issuance | shares		4,631,774
Convertible preferred stock, par value | $ / shares		$ 0.000001
Convertible preferred stock, per share price | $ / shares		$ 6.477
Gross proceeds from sale and issuance of convertible preferred stock		$ 30,000			26,021
Proceeds from exercise of stock options		26,000
Convertible preferred stock, issuance cost		200
Convertible preferred stock, conversion of other debt		$ 3,800
Series A Convertible Preferred Stock [Member]
Schedule of Capitalization [Line Items]
Net gain on extinguishment of convertible preferred stock					(1,300)
Series B Convertible Preferred Stock [Member]
Schedule of Capitalization [Line Items]
Net gain on extinguishment of convertible preferred stock					2,100
Series D Convertible Preferred Stock [Member]
Schedule of Capitalization [Line Items]
Convertible preferred stock, shares sale and issuance | shares	7,366,849
Convertible preferred stock, par value | $ / shares	$ 0.0001
Convertible preferred stock, per share price | $ / shares	$ 9.5699
Gross proceeds from sale and issuance of convertible preferred stock	$ 68,000				$ 67,998
Convertible preferred stock, issuance cost	$ 2,500
Convertible Preferred Stock [Member]
Schedule of Capitalization [Line Items]
Convertible preferred stock, shares outstanding | shares				0	0
Conversion to C-corporation [Member]
Schedule of Capitalization [Line Items]
Reverse stock split conversion ratio			0.02