Warrants - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended					3 Months Ended	6 Months Ended		12 Months Ended
	Aug. 22, 2016	Jan. 31, 2017	Sep. 30, 2016	Aug. 31, 2016	Aug. 31, 2015	Jul. 31, 2015	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2013
Common Stock Warrants [Line Items]
Proceed from private placement and equity issuances, gross								$ 65,600
(Gain) loss related to change in fair value								9,032	$ 0
Fair value of warrants							$ 15,128	15,128		$ 2,723
2015 Placement Common Stock Warrants | Insiders
Common Stock Warrants [Line Items]
Warrants issued					198,760	198,760
Exercise price					$ 5.00	$ 5.00
Common stock warrants, expiry term					5 years	5 years
2016 Placement Warrant
Common Stock Warrants [Line Items]
Warrants issued			1,380,745	1,380,745
Exercise price			$ 2.95	$ 2.95
Common stock warrants, expiry term			7 years	7 years
Proceed from private placement and equity issuances, gross			$ 13,800					$ 13,800
Fair value of warrants upon issuance under Private Placement	$ 2,700
Expected term (in years)	7 years							6 years 2 months 12 days		6 years 8 months 12 days
Expected volatility	61.60%							65.80%		63.60%
Risk-free interest rate	1.40%							2.00%		2.30%
Expected dividend yield	0.00%							0.00%		0.00%
(Gain) loss related to change in fair value							(2,800)	$ 4,000
Fair value of warrants							6,700	$ 6,700		$ 2,700
2017 Placement Warrants Liability
Common Stock Warrants [Line Items]
Warrants issued		1,720,512
Exercise price		$ 3.17
Common stock warrants, expiry term		7 years
Proceed from private placement and equity issuances, gross		$ 26,100
Fair value of warrants upon issuance under Private Placement		$ 3,400
Expected term (in years)		7 years						6 years 7 months 6 days
Expected volatility		62.90%						65.90%
Risk-free interest rate		2.20%						2.00%
Expected dividend yield		0.00%						0.00%
(Gain) loss related to change in fair value							(3,400)	$ 5,000
Fair value of warrants							$ 8,400	$ 8,400
Warrants exercisable term		6 months
Common Stock Warrant
Common Stock Warrants [Line Items]
Warrants issued											128,231
Exercise price											$ 5.84
Common stock warrants, expiration date								Dec. 16, 2023