Stockholders' Equity - Common Stock - Additional Information (Detail) - USD ($)						2 Months Ended	3 Months Ended	6 Months Ended		12 Months Ended
	Feb. 16, 2017	Dec. 15, 2016	Aug. 03, 2016	Jul. 25, 2016	Apr. 15, 2016	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Aug. 04, 2017	Mar. 10, 2017	Mar. 03, 2017	Feb. 22, 2017
Sale Of Stock [Line Items]
Common stock, shares issued								15,388,325		12,350,360
Proceeds from issuance of common stock, net								$ 7,332,239	$ 358,023
July 2016 Financing [Member]
Sale Of Stock [Line Items]
Common stock, shares issued				1,804,512
Purchase price of common stock				$ 2.49375
Warrant exercise price per share	$ 2.41
Unregistered warrants to purchase of common stock	526,315							2,449,129
Aggregate gross proceeds from sale of common stock and warrants				$ 4,500,000
Aggregate net proceeds from sale of common stock and warrants				$ 4,000,000
Reclassification of warrant liability to Additional Paid-in Capital	$ 1,400,000
Common stock shares issued upon conversion of warrants	211,860
July Warrants [Member]
Sale Of Stock [Line Items]
Warrants exercisable, stock issued				0.75
Warrant exercise price per share				$ 2.41
Warrants expiration date				Jan. 25, 2022
Unregistered warrants to purchase of common stock				1,353,384
July Wainwright Warrants [Member]
Sale Of Stock [Line Items]
Warrant exercise price per share				$ 3.1172
Warrants expiration date				Jul. 21, 2021
Unregistered warrants to purchase of common stock				90,226
August 2016 Financing [Member]
Sale Of Stock [Line Items]
Common stock, shares issued			3,244,120
Purchase price of common stock			$ 3.0825
Aggregate gross proceeds from sale of common stock and warrants			$ 10,000,000
Aggregate net proceeds from sale of common stock and warrants			$ 9,200,000
August Warrants [Member]
Sale Of Stock [Line Items]
Warrants exercisable, stock issued			0.5
Warrant exercise price per share			$ 3.03
Warrants expiration date			Feb. 03, 2022
Unregistered warrants to purchase of common stock			1,622,060
August Wainwright Warrants [Member]
Sale Of Stock [Line Items]
Warrant exercise price per share			$ 3.853125
Warrants expiration date			Jul. 29, 2021
Unregistered warrants to purchase of common stock			162,206
2016 Financings [Member]
Sale Of Stock [Line Items]
Common stock, shares issued							5,048,632
Aggregate gross proceeds from sale of common stock and warrants							$ 14,500,000
2016 Financings [Member] | Warrant Liability [Member]
Sale Of Stock [Line Items]
Total initial fair value of warrants issued								$ 4,899,459
Warrant Amendments [Member]
Sale Of Stock [Line Items]
Unregistered warrants to purchase of common stock		252,432
Amendment Date		Dec. 15, 2016
Reclassification of warrant liability to Additional Paid-in Capital		$ 207,000
Underwritten Public Offering [Member]
Sale Of Stock [Line Items]
Purchase price of common stock													$ 2.90	$ 2.90
Issuance of common stock, shares						2,775,861
Gross proceeds from public offering of common stock						$ 8,000,000
Proceeds from issuance of common stock, net						$ 7,300,000
FBR Sales Agreement [Member]
Sale Of Stock [Line Items]
Common stock, shares issued										56,000
Issuance of common stock, shares								0
Proceeds from issuance of common stock, net										$ 296,000
Common stock, shares issuable					649,074
Common stock , weighted average price per share										$ 5.45
FBR Sales Agreement [Member] | Subsequent Event [Member]
Sale Of Stock [Line Items]
Entity public float											$ 29,500,000
Entity public float, common stock shares											12,846,511
Common stock, closing price											$ 2.30
FBR Sales Agreement [Member] | Maximum [Member]
Sale Of Stock [Line Items]
Common stock, value of shares issuable												$ 20,000,000