Hercules Capital, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 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	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Schedule Of Investments [Line Items]
Investments at Fair Value	$ 3,560,513	$ 3,248,046
Industry Sector Concentration Risk \| Total Industry Sectors
Schedule Of Investments [Line Items]
Investments at Fair Value	3,560,513	3,248,046
Industry Sector Concentration Risk \| Drug Discovery & Development
Schedule Of Investments [Line Items]
Investments at Fair Value	1,125,617	1,257,699
Industry Sector Concentration Risk \| Software
Schedule Of Investments [Line Items]
Investments at Fair Value	1,018,236	764,985
Industry Sector Concentration Risk \| Healthcare Services, Other
Schedule Of Investments [Line Items]
Investments at Fair Value	574,750	300,079
Industry Sector Concentration Risk \| Consumer & Business Services
Schedule Of Investments [Line Items]
Investments at Fair Value	355,831	525,973
Industry Sector Concentration Risk \| Diversified Financial Services
Schedule Of Investments [Line Items]
Investments at Fair Value	112,709	114,722
Industry Sector Concentration Risk \| Electronics & Computer Hardware
Schedule Of Investments [Line Items]
Investments at Fair Value	96,125	20,324
Industry Sector Concentration Risk \| Information Services
Schedule Of Investments [Line Items]
Investments at Fair Value	81,266	126,605
Industry Sector Concentration Risk \| Medical Devices & Equipment
Schedule Of Investments [Line Items]
Investments at Fair Value	56,153	22,096
Industry Sector Concentration Risk \| Space Technologies
Schedule Of Investments [Line Items]
Investments at Fair Value	46,082	0
Industry Sector Concentration Risk \| Biotechnology Tools
Schedule Of Investments [Line Items]
Investments at Fair Value	35,311	48,381
Industry Sector Concentration Risk \| Sustainable and Renewable Technology
Schedule Of Investments [Line Items]
Investments at Fair Value	27,858	9,581
Industry Sector Concentration Risk \| Communications & Networking
Schedule Of Investments [Line Items]
Investments at Fair Value	26,465	29,400
Industry Sector Concentration Risk \| Manufacturing Technology
Schedule Of Investments [Line Items]
Investments at Fair Value	2,096	11,006
Industry Sector Concentration Risk \| Consumer & Business Products
Schedule Of Investments [Line Items]
Investments at Fair Value	1,285	2,589
Industry Sector Concentration Risk \| Semiconductors
Schedule Of Investments [Line Items]
Investments at Fair Value	655	1,205
Industry Sector Concentration Risk \| Media/Content/Info
Schedule Of Investments [Line Items]
Investments at Fair Value	55	12,704
Industry Sector Concentration Risk \| Drug Delivery
Schedule Of Investments [Line Items]
Investments at Fair Value	19	21
Industry Sector Concentration Risk \| Surgical Devices
Schedule Of Investments [Line Items]
Investments at Fair Value	$ 0	$ 676
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Total Industry Sectors
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	100.00%	100.00%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Drug Discovery & Development
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	31.60%	38.70%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Software
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	28.60%	23.60%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Healthcare Services, Other
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	16.10%	9.30%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Consumer & Business Services
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	10.00%	16.20%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Diversified Financial Services
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	3.20%	3.50%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Electronics & Computer Hardware
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	2.70%	0.60%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Information Services
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	2.30%	3.90%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Medical Devices & Equipment
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	1.60%	0.70%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Space Technologies
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	1.30%	0.00%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Biotechnology Tools
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	1.00%	1.50%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Sustainable and Renewable Technology
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.80%	0.30%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Communications & Networking
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.70%	0.90%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Manufacturing Technology
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.10%	0.30%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Consumer & Business Products
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.10%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Semiconductors
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.00%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Media/Content/Info
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.40%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Drug Delivery
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.00%
Industry Sector Concentration Risk \| Industry Sub Sector Investments Benchmark \| Surgical Devices
Schedule Of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.00%