Warrants - Summary of Warrant Activity (Detail) - $ / shares
 1 Months Ended 12 Months Ended
Nov. 18, 2015
Apr. 01, 2015
Oct. 08, 2013
Oct. 07, 2013
Sep. 30, 2013
Jul. 06, 2013
Apr. 10, 2013
Jul. 31, 2014
Mar. 31, 2014
Feb. 28, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Nov. 12, 2015
Nov. 11, 2015
Feb. 11, 2013
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 6.78          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     1,136,000 1,797,000 1,102,000      
Warrants Issued (shares)     10,680 10,680 15,721 3,928   84,106 5,270 3,320 3,450,000   9,000      
Warrants Exercised (shares)                     0 (190,000) (118,000)      
Warrants Expired (shares) (14,665) (19,138)                 (154,000) (471,000) (36,000)      
Warrant Adjustments (shares)             838,889       0   840,000      
Warrants Outstanding, Ending Balance (shares)                     4,432,000 1,136,000 1,797,000      
Common stock issued upon closing initial public offering fair value (usd per share)             $ 10.00                  
Common shares issuable upon exercise of warrants or rights (shares)             838,889                  
Number of warrants effected with adjusted exercise price (shares)             1,656,860                  
Amended exercise price per warrant (usd per share) $ 4.00                         $ 4.00 $ 10.00  
Warrant Issued With | Non-Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 6.82          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     1,061,000 1,706,000 294,000      
Warrants Issued (shares)                     3,450,000   0      
Warrants Exercised (shares)                     0 (174,000) (84,000)      
Warrants Expired (shares)                     (139,000) (471,000) (36,000)      
Warrant Adjustments (shares)                     0   1,532,000      
Warrants Outstanding, Ending Balance (shares)                     4,372,000 1,061,000 1,706,000      
Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 4.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     75,000 91,000 808,000      
Warrants Issued (shares)                     0   9,000      
Warrants Exercised (shares)                     0 (16,000) (34,000)      
Warrants Expired (shares)                     (15,000) 0 0      
Warrant Adjustments (shares)                     0   (692,000)      
Warrants Outstanding, Ending Balance (shares)                     60,000 75,000 91,000      
Debt Guarantee | Warrant Issued With | Non-Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 4.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 174,000 228,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 (174,000) (54,000)      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   0      
Warrants Outstanding, Ending Balance (shares)                     0 0 174,000      
Debt Guarantee | Warrant Issued With | Non-Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 10.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 238,000 0      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 (238,000) 0      
Warrant Adjustments (shares)                     0   238,000      
Warrants Outstanding, Ending Balance (shares)                     0 0 238,000      
Debt Guarantee | Warrant Issued With | Non-Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 15.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     353,000 586,000 0      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     (120,000) (233,000) 0      
Warrant Adjustments (shares)                     0   586,000      
Warrants Outstanding, Ending Balance (shares)                     233,000 353,000 586,000      
Debt Guarantee | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 10.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 13,000 0      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 (13,000) 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   13,000      
Warrants Outstanding, Ending Balance (shares)                     0 0 13,000      
Debt Guarantee | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 25.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 212,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (212,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Debt Guarantee | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 25.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 100,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (100,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Debt Guarantee | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 32.45          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 40,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (40,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Debt Guarantee | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 42.50          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 38,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (38,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Debt Guarantee | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 42.50          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 37,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (37,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Series A Preferred Stock | Warrant Issued With | Non-Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 14.10          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 66,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 (30,000)      
Warrants Expired (shares)                     0 0 (36,000)      
Warrant Adjustments (shares)                     0   0      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Series B Preferred Stock | Instrument Type One | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 4.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 0      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     (15,000) 0 0      
Warrant Adjustments (shares)                     15,000   0      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Series B Preferred Stock | Instrument Type Two | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 10.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     15,000 18,000 0      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 (3,000) (34,000)      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     (15,000)   52,000      
Warrants Outstanding, Ending Balance (shares)                     0 15,000 18,000      
Series B Preferred Stock | Instrument Type Three | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 25.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 52,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (52,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Financing | Warrant Issued With | Non-Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 10.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     243,000 243,000 0      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   243,000      
Warrants Outstanding, Ending Balance (shares)                     243,000 243,000 243,000      
Financing | Warrant Issued With | Non-Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 15.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     436,000 436,000 0      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   436,000      
Warrants Outstanding, Ending Balance (shares)                     436,000 436,000 436,000      
Consulting | Warrant Issued With | Non-Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 10.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     29,000 29,000 0      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     (19,000) 0 0      
Warrant Adjustments (shares)                     0   29,000      
Warrants Outstanding, Ending Balance (shares)                     10,000 29,000 29,000      
Financing | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 4.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 0      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     60,000   0      
Warrants Outstanding, Ending Balance (shares)                     60,000 0 0      
Financing | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 10.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     60,000 60,000 0      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     (60,000)   60,000      
Warrants Outstanding, Ending Balance (shares)                     0 60,000 60,000      
Financing | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 25.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 60,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (60,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Financing | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 42.50          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 75,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (75,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Financing | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 42.50          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 55,000      
Warrants Issued (shares)                     0   3,000      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (58,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Financing | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 42.50          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 121,000      
Warrants Issued (shares)                     0   6,000      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (127,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Consulting | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 12.50          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 4,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (4,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Consulting | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 14.10          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 10,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (10,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
Consulting | Warrant Issued For | Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 25.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 4,000      
Warrants Issued (shares)                     0   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   (4,000)      
Warrants Outstanding, Ending Balance (shares)                     0 0 0      
IPO                                
Class of Warrants Outstanding [Roll Forward]                                
Price of warrants issued to related party adjustment for IPO (usd per share)                               $ 15.00
Class of warrant issued (in shares)                               530,022
2015 Offering                                
Class of Warrants Outstanding [Roll Forward]                                
Amended exercise price per warrant (usd per share)                           $ 5.00    
2015 Offering | Warrant Issued With | Non-Derivative Warrants                                
Class of Warrant or Right [Line Items]                                
Warrants exercise price (usd per share)                     $ 5.00          
Class of Warrants Outstanding [Roll Forward]                                
Warrants Outstanding, Beginning Balance (shares)                     0 0 0      
Warrants Issued (shares)                     3,450,000   0      
Warrants Exercised (shares)                     0 0 0      
Warrants Expired (shares)                     0 0 0      
Warrant Adjustments (shares)                     0   0      
Warrants Outstanding, Ending Balance (shares)                     3,450,000 0 0