N-2 - $ / shares
Sep. 01, 2022
Jun. 30, 2022
Dec. 31, 2021
Cover [Abstract]      
Entity Central Index Key 0001314966    
Amendment Flag false    
Document Type N-CSRS    
Entity Registrant Name BlackRock Health Sciences Trust    
General Description of Registrant [Abstract]      
Investment Objectives and Practices [Text Block]
BlackRock Health Sciences Trust’s (BME) (the “Trust”)
investment objective is to provide total return through a combination of current income, current gains and long-term capital appreciation. The Trust seeks to achieve its investment objective by investing, under normal market conditions, at least 80% of its total assets in equity securities of companies engaged in the health sciences and related industries and equity derivatives with exposure to the health sciences industry. The Trust seeks to pursue this goal primarily by investing in a portfolio of equity securities and by employing a strategy of writing (selling) call and put options. 		   
Share Price [Table Text Block]
Market Price and Net Asset Value Per Share Summary
 
    
06/30/22
     
12/31/21
     
Change
     
High
     
Low
  
Closing Market Price
   $ 42.40      $ 48.50        (12.58 )%     $  48.50      $  39.97  
Net Asset Value
     41.95        47.96        (12.53 )       47.96        39.35  
    
Lowest Price or Bid   $ 39.97  
Highest Price or Bid   48.5  
Lowest Price or Bid, NAV   39.35  
Highest Price or Bid, NAV   47.96  
Latest Share Price   42.4 $ 48.5
Latest NAV   $ 41.95 $ 47.96
Capital Stock, Long-Term Debt, and Other Securities [Abstract]      
Outstanding Security, Held [Shares]   13,493,047