Sponsored Research and Clinical Trial Agreements - summary of Helocyte’s expense related to its clinical research arrangements (Detail) - Helocyte Inc [Member] - USD ($) $ in Thousands  | 
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2018  | 
Jun. 30, 2017  | 
Jun. 30, 2018  | 
Jun. 30, 2017  | 
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| Payments For Research And Development Expenses | $ 204 | $ 547 | $ 204 | $ 1,282 | 
| COH Triplex Clinical Research and Support [Member] | ||||
| Payments For Research And Development Expenses | 0 | 535 | 0 | 1,035 | 
| COH PepVax Clinical Research And Support [Member] | ||||
| Payments For Research And Development Expenses | 0 | 0 | 0 | 235 | 
| COH Pentamer clinical research and support [Member] | ||||
| Payments For Research And Development Expenses | $ 204 | $ 12 | $ 204 | $ 12 | 
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