Quarterly report pursuant to Section 13 or 15(d)


Cover - shares
9 Months Ended
Sep. 30, 2023
Oct. 26, 2023
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2023  
Document Transition Report false  
Entity File Number 814-00702  
Entity Registrant Name HERCULES CAPITAL, INC.  
Entity Incorporation, State or Country Code MD  
Entity Tax Identification Number 74-3113410  
Entity Address, Address Line One 400 Hamilton Ave  
Entity Address, Address Line Two Suite 310  
Entity Address, City or Town Palo Alto  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 94301  
City Area Code 650  
Local Phone Number 289-3060  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   151,139,477
Entity Central Index Key 0001280784  
Document Fiscal Year Focus 2023  
Document Fiscal Period Focus Q3  
Current Fiscal Year End Date --12-31  
Amendment Flag false  
Common Stock Par Value $0.001 Per Share    
Document Information [Line Items]    
Title of 12(b) Security Common Shares, par value $0.001 per share  
Trading Symbol HTGC  
Security Exchange Name NYSE  
6.25% Notes Due 2033    
Document Information [Line Items]    
Title of 12(b) Security 6.25% Notes due 2033  
Trading Symbol HCXY  
Security Exchange Name NYSE