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)

v3.19.2
Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Summary Of Significant Accounting Policies [Line Items]        
Total potentially dilutive securities 7,228,185 7,403,916 7,228,185 7,403,916
Warrant Issued to Private Investors [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Total potentially dilutive securities 4,702,354 3,035,688 4,702,354 3,035,688
Employee Stock Option [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Total potentially dilutive securities 576,293 856,635 576,293 856,635
Restricted Stock Units (RSUs) [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Total potentially dilutive securities 1,949,538 2,640,034 1,949,538 2,640,034
Performance Share Units [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Total potentially dilutive securities   871,559   871,559