Quarterly report pursuant to Section 13 or 15(d)

Capital Structure - Additional Information (Detail)

Capital Structure - Additional Information (Detail) - USD ($)							3 Months Ended	13 Months Ended
	Mar. 31, 2018	Jul. 25, 2017	Jul. 27, 2016	Nov. 02, 2015	Jun. 12, 2015	Aug. 01, 2014	Mar. 31, 2018	Jun. 30, 2014	Dec. 31, 2017
Class of Stock [Line Items]
Common stock, shares authorized	200,000,000						200,000,000		200,000,000
Common stock, par value	$ 0.0001						$ 0.0001		$ 0.0001
Net proceeds from initial public offering						$ 35,000,000
Initial public offering, closing date							Aug. 01, 2014
Initial public offering, units description							In August 2014, the Company completed an initial public offering (“IPO”), raising net proceeds of $35.0 million after underwriting discounts, commissions and offering expenses payable by us, through the issuance and sale of our units, which consisted of one share of common stock, one Class A Warrant to purchase one share of common stock at an exercise price of $4.80 per share and one Class B Warrant to purchase one-half share of common stock at an exercise price of $4.00 per full share (“Units”).
Proceeds from exercise of warrants							$ 3,875
Number of warrants or rights outstanding	36,267,603						36,267,603		36,270,103
Common stock, voting rights							The holders of shares of common stock are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings.
Dividends declared or paid	$ 0
8.00% Convertible Notes due May 31, 2015 [Member]
Class of Stock [Line Items]
Convertible Notes, principal amount								$ 15,000,000
Convertible Notes, interest rate								8.00%
Convertible Notes, due date								May 31, 2015
2016 Warrants [Member]
Class of Stock [Line Items]
Number of warrants or rights outstanding	14,000,000						14,000,000		14,000,000
2017 Warrants [Member]
Class of Stock [Line Items]
Number of warrants or rights outstanding	15,997,500						15,997,500		16,000,000
Private Placement [Member]
Class of Stock [Line Items]
Number of shares issued					4,728,128
Warrants to purchase shares of common stock	189,126				2,364,066		189,126
Net proceeds received					$ 18,300,000
Warrant exercise price per share	$ 4.65				$ 8.00		$ 4.65
Warrants expiration period					3 years
Warrant expiration date							Jun. 11, 2020
Initial Public Offering [Member]
Class of Stock [Line Items]
Conversion of Convertible Notes together with accrued and unpaid interest into common stock, shares						5,109,988
Follow-on Offering [Member]
Class of Stock [Line Items]
Number of shares issued		32,000,000	14,000,000
Warrants to purchase shares of common stock	2,500						2,500
Aggregate gross sales proceeds from common stock		$ 40,000,000	$ 35,000,000
Net proceeds received		$ 37,100,000	$ 32,000,000
Follow-on Offering [Member] \| CMPO Warrants [Member]
Class of Stock [Line Items]
Warrants to purchase shares of common stock		16,000,000	14,000,000
Follow-on Offering [Member] \| 2016 Warrants [Member]
Class of Stock [Line Items]
Warrant exercise price per share			$ 3.00
Warrant expiration term			5 years
Fair value of warrants			$ 18,600,000
Issuance costs allocated to warrants			$ 1,600,000
Follow-on Offering [Member] \| 2017 Warrants [Member]
Class of Stock [Line Items]
Warrant exercise price per share		$ 1.55
Warrant expiration term		5 years
Fair value of warrants		$ 12,400,000
Issuance costs allocated to warrants		$ 900,000
Note Warrants [Member]
Class of Stock [Line Items]
Warrant exercise price per share						$ 3.00
Warrants expiration period							5 years
Number of warrants or rights outstanding	3,315,878					3,321,416	3,315,878		3,315,878
Class B Warrants [Member]
Class of Stock [Line Items]
Warrant expiration date							Nov. 02, 2015
Warrants exercised				4,812,328
Common stock shares issued upon exercise of warrants				2,406,164
Proceeds from exercise of warrants				$ 9,600,000
Class B Warrants [Member] \| Initial Public Offering [Member]
Class of Stock [Line Items]
Warrant exercise price per share						$ 4.00
Representative's Warrant [Member]
Class of Stock [Line Items]
Warrants to purchase shares of common stock	206,410						206,410
Warrant exercise price per share	$ 7.50						$ 7.50
Warrant expiration date							Jul. 28, 2019
Class of warrant purchase percentage	3.00%						3.00%
Warrant exercisable period							180 days
Number of warrants or rights outstanding	206,410						206,410		206,410
Class A Warrants [Member]
Class of Stock [Line Items]
Warrant expiration date							Feb. 01, 2017
Class A Warrants [Member] \| Initial Public Offering [Member]
Class of Stock [Line Items]
Warrant exercise price per share						$ 4.80