Organization, Basis of Presentation and Liquidity (Details Narrative) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
Mar. 08, 2019
Aug. 31, 2021
Dec. 31, 2021
Dec. 31, 2020
Jan. 01, 2022
Dec. 21, 2021
Mar. 05, 2021
May 01, 2020
Mar. 07, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Proceeds from sale of common shares     $ 30,865 $ 5,127          
Common stock, shares issued     169,477,347 153,095,883          
Retained earning accumulated deficit     $ 337,100            
Working capital     64,400            
Shareholders' equity     90,900            
Cash, cash equivalents and marketable equity securities     58,400            
Subsequent Event [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Upfront payment         $ 50,000        
Subsequent Event [Member] | Israeli Innovation Authority [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Upfront payment         12,100        
Subsequent Event [Member] | Hadasit [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Upfront payment         $ 8,900        
Merger Consideration [Member] | Parent Company [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Stock-for-stock transaction 24,695,898                
Value of equity shares issued $ 32,400                
Business combination purchase price consideration $ 52,600                
Merger Agreement [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Ownership percentage                 38.00%
Sales Agreement [Member] | Parent Company [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Proceeds from sale of common shares     $ 35,900            
Shares authorized, value           $ 64,100 $ 50,000    
Common stock, shares issued     14,908,735            
Sale of stock price per share     $ 2.41            
Sales Agreement [Member] | Parent Company [Member] | Common Stock [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Additional shares authorized, value             $ 25,000    
New Sales Agreement [Member] | Parent Company [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Proceeds from sale of common shares     $ 300            
Shares authorized, value           $ 64,100      
Common stock, shares issued     108,200            
Sale of stock price per share     $ 2.55            
Available for sale securities     $ 63,900            
Juvenescence Limited [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Proceeds from debt security   $ 24,600              
Asterias [Member] | Merger Consideration [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Stock-for-stock transaction $ 0.71                
Asterias [Member] | Merger Consideration [Member] | Restricted Stock [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Stock-for-stock transaction 58,085                
Cantor Fitzgerald And Co Member [Member] | Two Thousand Seventeen Sales Agreement [Member] | Maximum [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Shares authorized, value               $ 25,000  
Onco Cyte Corporation and AgeX Therapeutics Inc [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Proceeds from sale of common shares     10,100            
Roche Agreement [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Upfont payment received     50,000            
Collaboration License Agreement [Member]                  
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]                  
Milestone payments     $ 620,000