Hercules Capital, Inc. Quarterly report [Sections 13 or 15(d)]

Quarterly report [Sections 13 or 15(d)]

Investments - Schedule of Fair Value Portfolio by Industry Sector (Details)

Investments - Schedule of Fair Value Portfolio by Industry Sector (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2025	Dec. 31, 2024
Schedule Of Investments [Line Items]
Investments at Fair Value	$ 4,176,486	$ 3,659,978
Industry Sector Concentration Risk \| Total Industry Sectors
Schedule Of Investments [Line Items]
Investments at Fair Value	4,176,486	3,659,978
Industry Sector Concentration Risk \| Software
Schedule Of Investments [Line Items]
Investments at Fair Value	1,471,080	1,081,100
Industry Sector Concentration Risk \| Drug Discovery & Development
Schedule Of Investments [Line Items]
Investments at Fair Value	1,035,769	1,080,390
Industry Sector Concentration Risk \| Healthcare Services, Other
Schedule Of Investments [Line Items]
Investments at Fair Value	755,202	610,184
Industry Sector Concentration Risk \| Consumer & Business Services
Schedule Of Investments [Line Items]
Investments at Fair Value	375,233	372,641
Industry Sector Concentration Risk \| Defense Technologies
Schedule Of Investments [Line Items]
Investments at Fair Value	139,991	0
Industry Sector Concentration Risk \| Diversified Financial Services
Schedule Of Investments [Line Items]
Investments at Fair Value	118,110	113,491
Industry Sector Concentration Risk \| Medical Devices & Equipment
Schedule Of Investments [Line Items]
Investments at Fair Value	75,436	74,962
Industry Sector Concentration Risk \| Electronics & Computer Hardware
Schedule Of Investments [Line Items]
Investments at Fair Value	50,666	162,888
Industry Sector Concentration Risk \| Biotechnology Tools
Schedule Of Investments [Line Items]
Investments at Fair Value	34,836	35,434
Industry Sector Concentration Risk \| Communications & Networking
Schedule Of Investments [Line Items]
Investments at Fair Value	27,937	27,700
Industry Sector Concentration Risk \| Information Services
Schedule Of Investments [Line Items]
Investments at Fair Value	24,233	24,356
Industry Sector Concentration Risk \| Sustainable and Renewable Technology
Schedule Of Investments [Line Items]
Investments at Fair Value	22,723	27,696
Industry Sector Concentration Risk \| Manufacturing Technology
Schedule Of Investments [Line Items]
Investments at Fair Value	20,650	1,162
Industry Sector Concentration Risk \| Electronics & Computer Hardware
Schedule Of Investments [Line Items]
Investments at Fair Value	15,446	45,700
Industry Sector Concentration Risk \| Consumer & Business Products
Schedule Of Investments [Line Items]
Investments at Fair Value	8,663	1,497
Industry Sector Concentration Risk \| Semiconductors
Schedule Of Investments [Line Items]
Investments at Fair Value	345	704
Industry Sector Concentration Risk \| Media/Content/Info
Schedule Of Investments [Line Items]
Investments at Fair Value	157	63
Industry Sector Concentration Risk \| Drug Delivery
Schedule Of Investments [Line Items]
Investments at Fair Value	$ 9	$ 10
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Total Industry Sectors
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	100.00%	100.00%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Software
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	35.20%	29.50%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Drug Discovery & Development
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	24.80%	29.50%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Healthcare Services, Other
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	18.10%	16.70%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Consumer & Business Services
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	9.00%	10.20%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Defense Technologies
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	3.40%	0.00%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Diversified Financial Services
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	2.80%	3.10%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Medical Devices & Equipment
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	1.80%	2.00%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Electronics & Computer Hardware
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	1.20%	4.50%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Biotechnology Tools
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.80%	1.00%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Communications & Networking
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.70%	0.80%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Information Services
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.60%	0.70%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Sustainable and Renewable Technology
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.50%	0.80%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Manufacturing Technology
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.50%	0.00%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Electronics & Computer Hardware
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.40%	1.20%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Consumer & Business Products
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.20%	0.00%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Semiconductors
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.00%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Media/Content/Info
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.00%
Industry Sector Concentration Risk \| Industry Sector Investments Benchmark \| Drug Delivery
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.00%