Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Detail)	Dec. 31, 2016 shares
Class Of Stock [Line Items]
Common stock reserved for future issuance	7,740,340
Private Placement [Member] | Warrant [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	4,153,620
Underwriters Agreement [Member] | Warrant [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	182,600
Loan and Security Agreement [Member] | Warrant [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	65,892
Cambridge Securities Agreement [Member] | Warrant [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	1,224,138
Hercules Securities Agreement [Member] | Warrant [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	306,748
Non-Employee Director Plan [Member] | Employee Stock Option [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	3,200
2009 Stock Incentive Plan [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	1,414,226
Assignment Agreement [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	80,000
BDL [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	309,916