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Commitments and Contingencies - Additional Information (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2006
Commitments And Contingencies [Line Items]      
Restricted time deposits $ 2,072 $ 4,145  
Lease obligation liability 1,925    
Research and Pre-Clinical Stage Development Programs [Member]      
Commitments And Contingencies [Line Items]      
Maximum future milestone payments 11,000    
FibroGen, Inc. [Member]      
Commitments And Contingencies [Line Items]      
Restricted time deposits     $ 7,300
Prior period reclassification adjustment $ 2,100    
Description of lessee leasing arrangements, operating leases The agreement also included an expansion option to occupy part of an adjacent building, for which the Company gave notice to its landlord that it would not exercise this expansion option    
Lease incentive receivable from land lord through expansion option not used $ 5,000    
Lease obligation liability 1,500    
FibroGen, Inc. [Member] | Accrued and Other Current Liabilities [Member]      
Commitments And Contingencies [Line Items]      
Lease obligation liability 400    
FibroGen, Inc. [Member] | Long Term Portion of Lease Obligations [Member]      
Commitments And Contingencies [Line Items]      
Lease obligation liability $ 1,100