Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Warrant Liabilities And Convertible Notes At Fair Value (Detail)

v3.8.0.1
Fair Value Measurements - Warrant Liabilities And Convertible Notes At Fair Value (Detail) - $ / shares
 1 Months Ended 12 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2017
Dec. 31, 2016
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Expected dividend yield     0.00%  
Expected volatility     70.00%  
Strike price     $ 1.01  
Warrants Issuable [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate 1.89% 1.14%    
Expected dividend yield 0.00% 0.00%    
Expected term in years 4 years 2 months 12 days 5 years    
Expected volatility 91.00% 118.85%    
Avenue [Member] | Convertible Debt [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Expected dividend yield       0.00%
Expected volatility       63.10%
Avenue [Member] | Minimum [Member] | Convertible Debt [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate       0.62%
Expected term in years       6 months
Avenue [Member] | Maximum [Member] | Convertible Debt [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate       1.20%
Expected term in years       2 years
Avenue [Member] | Warrant [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate       2.45%
Expected dividend yield       0.00%
Expected term in years       10 years
Expected volatility       87.00%
Helocyte [Member] | Convertible Debt [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Expected dividend yield     0.00% 0.00%
Expected volatility     52.40% 61.70%
Helocyte [Member] | Minimum [Member] | Convertible Debt [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate     1.53% 0.74%
Expected term in years     6 months 9 months
Helocyte [Member] | Maximum [Member] | Convertible Debt [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate     1.72% 1.17%
Expected term in years     10 months 28 days 1 year 10 months 28 days
Helocyte [Member] | Warrant [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Expected dividend yield     0.00% 0.00%
Expected volatility     70.00% 70.00%
Strike price     $ 0.46 $ 0.44
Helocyte [Member] | Warrant [Member] | Minimum [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate     2.04% 1.82%
Expected term in years     3 years 6 months 4 years 6 months
Helocyte [Member] | Warrant [Member] | Maximum [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate     2.08% 1.91%
Expected term in years     3 years 11 months 1 day 4 years 11 months 1 day
Caelum Warrant Liabilities [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Expected dividend yield     0.00%  
Expected volatility     70.00%  
Strike price     $ 1.43  
Caelum Warrant Liabilities [Member] | Minimum [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate     2.154%  
Expected term in years     4 years 6 months 29 days  
Caelum Warrant Liabilities [Member] | Maximum [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate     2.168%  
Expected term in years     4 years 8 months 16 days  
Caelum Convertible Notes [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Expected dividend yield     0.00%  
Expected volatility     70.00%  
Caelum Convertible Notes [Member] | Minimum [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate     1.506%  
Expected term in years     5 months 16 days  
Caelum Convertible Notes [Member] | Maximum [Member]        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Risk-free interest rate     1.851%  
Expected term in years     1 year 8 months 12 days