Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Derivative Contingently Issuable Warrant liabilities (Detail)

v3.19.1
Fair Value Measurements - Derivative Contingently Issuable Warrant liabilities (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Additions   $ 9,914
Caelum Warrant Liabilities [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Beginning balance $ 222 0
Additions   225
Change in fair value 769 (3)
Ending balance 991 222
Helocyte [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Beginning balance 87 167
Change in fair value (87) (80)
Ending balance 0 87
Helocyte [Member] | Convertible Debt [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Beginning balance 4,700 4,487
Change in fair value of derivative liabilities (4,408)  
Change in fair value (292) 213
Ending balance 0 4,700
Caelum Convertible Notes [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Beginning balance 10,059 0
Additions   9,914
Change in fair value of derivative liabilities (145) 145
Ending balance $ 9,914 $ 10,059