Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Financial Instruments Measured at Fair Value on Recurring Basis (Detail)

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Fair Value Measurements - Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - USD ($)
$ in Thousands
Jun. 30, 2016
Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term investments, at fair value $ 766 $ 2,485
Helocyte convertible note, at fair value 1,000 0
Warrant [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities 99 114
Warrant [Member] | Contingently Issuable Warrants [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities 203  
Fair Value, Inputs, Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term investments, at fair value 0 0
Helocyte convertible note, at fair value 0  
Fair Value, Inputs, Level 1 [Member] | Warrant [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities   0
Fair Value, Inputs, Level 1 [Member] | Warrant [Member] | Contingently Issuable Warrants [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities 0  
Fair Value, Inputs, Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term investments, at fair value 0 0
Helocyte convertible note, at fair value 0  
Fair Value, Inputs, Level 2 [Member] | Warrant [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities   0
Fair Value, Inputs, Level 2 [Member] | Warrant [Member] | Contingently Issuable Warrants [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities 0  
Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term investments, at fair value 766 2,485
Helocyte convertible note, at fair value 1,000  
Fair Value, Inputs, Level 3 [Member] | Warrant [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities 99 $ 114
Fair Value, Inputs, Level 3 [Member] | Warrant [Member] | Contingently Issuable Warrants [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities $ 203