Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail)

v3.19.1
Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares
 3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Summary Of Significant Accounting Policies [Line Items]    
Total potentially dilutive securities 7,601,654 7,420,048
Financing Warrant to Purchase Common Stock [Member]    
Summary Of Significant Accounting Policies [Line Items]    
Total potentially dilutive securities   13,889
Warrant Issued to Private Investors [Member]    
Summary Of Significant Accounting Policies [Line Items]    
Total potentially dilutive securities 4,702,354 3,035,688
Employee Stock Option [Member]    
Summary Of Significant Accounting Policies [Line Items]    
Total potentially dilutive securities 576,293 857,507
Restricted Stock Units (RSUs) [Member]    
Summary Of Significant Accounting Policies [Line Items]    
Total potentially dilutive securities 2,323,007 2,641,405
Performance Share Units [Member]    
Summary Of Significant Accounting Policies [Line Items]    
Total potentially dilutive securities   871,559