Debt - Narrative (Details) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||||||||||||||||
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Mar. 10, 2025
USD ($)
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Feb. 05, 2025
USD ($)
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Nov. 26, 2024
USD ($)
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Jul. 16, 2024
USD ($)
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Jul. 09, 2024
USD ($)
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Oct. 27, 2020
USD ($)
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Jul. 16, 2019
USD ($)
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Mar. 31, 2025
USD ($)
creditFacility
$ / shares
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Mar. 31, 2024
USD ($)
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Dec. 31, 2024
USD ($)
creditFacility
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Jun. 23, 2022
USD ($)
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Jun. 22, 2022
USD ($)
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Jan. 20, 2022
USD ($)
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Sep. 16, 2021
USD ($)
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Mar. 04, 2021
USD ($)
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Nov. 04, 2020
USD ($)
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Jun. 03, 2020
USD ($)
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Feb. 05, 2020
USD ($)
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Sep. 24, 2018
USD ($)
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| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 2,564,345 | $ 2,329,475 | |||||||||||||||||||||||
| Repayments of debt | 360,812 | $ 207,000 | |||||||||||||||||||||||
| Restricted cash | 3,162 | 10,110 | $ 3,297 | ||||||||||||||||||||||
| Loss on extinguishment of debt | $ 15 | $ 0 | |||||||||||||||||||||||
| Number of available credit facilities | creditFacility | 2 | 2 | |||||||||||||||||||||||
| Credit Facility | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Line of credit interest rate | 6.32% | 7.63% | |||||||||||||||||||||||
| Debt average amount outstanding | $ 390,000 | $ 338,000 | |||||||||||||||||||||||
| SMBC LC Facility | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Maximum borrowing capacity | 300,000 | ||||||||||||||||||||||||
| VIE | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Restricted cash | 3,162 | 3,297 | |||||||||||||||||||||||
| SBA Debentures | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Maximum borrowing capacity | 350,000 | 350,000 | |||||||||||||||||||||||
| Outstanding principal balances | [1] | $ 350,000 | 350,000 | ||||||||||||||||||||||
| Debt instrument, interest rate | 4.89% | ||||||||||||||||||||||||
| SBA Debentures | HC IV | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Debt instrument, license description | HC IV and SBIC V each received their licenses to operate as an SBIC on October 27, 2020 and July 9, 2024, respectively, and each license has a 10 year term | ||||||||||||||||||||||||
| License term | 10 years | ||||||||||||||||||||||||
| Maximum borrowing capacity | $ 175,000 | $ 175,000 | 175,000 | ||||||||||||||||||||||
| Outstanding principal balances | $ 175,000 | ||||||||||||||||||||||||
| SBA Debentures | Hercules SBIC V, L.P. | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Debt instrument, license description | HC IV and SBIC V each received their licenses to operate as an SBIC on October 27, 2020 and July 9, 2024, respectively, and each license has a 10 year term | ||||||||||||||||||||||||
| License term | 10 years | ||||||||||||||||||||||||
| Maximum borrowing capacity | $ 175,000 | $ 175,000 | 175,000 | ||||||||||||||||||||||
| Outstanding principal balances | $ 120,000 | ||||||||||||||||||||||||
| July 2024 Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 105,000 | ||||||||||||||||||||||||
| Debt instrument, interest rate | 4.77% | ||||||||||||||||||||||||
| Maturity date | Jul. 16, 2024 | ||||||||||||||||||||||||
| Debt instrument, redemption, description | On July 16, 2019, the Company issued $105.0 million in aggregate principal amount of 4.770% interest-bearing unsecured notes due on July 16, 2024 (the “July 2024 Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement notes offering. | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the July 2024 Notes was due semiannually. | ||||||||||||||||||||||||
| Debt instrument, collateral | The July 2024 Notes were the general unsecured obligations of the Company that ranked pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. | ||||||||||||||||||||||||
| Repayments of debt | $ 105,000 | ||||||||||||||||||||||||
| Repayment of accrued interest | $ 2,500 | ||||||||||||||||||||||||
| February 2025 Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 0 | 50,000 | $ 50,000 | ||||||||||||||||||||||
| Debt instrument, interest rate | 4.28% | ||||||||||||||||||||||||
| Maturity date | Feb. 05, 2025 | ||||||||||||||||||||||||
| Debt instrument, redemption, description | On February 5, 2020, the Company issued $50.0 million in aggregate principal amount of 4.280% interest-bearing unsecured notes due February 5, 2025 (the “February 2025 Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement notes offering | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the February 2025 Notes was due semiannually | ||||||||||||||||||||||||
| Debt instrument, collateral | The February 2025 Notes were the general unsecured obligations of the Company that ranked pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. | ||||||||||||||||||||||||
| Repayments of debt | $ 50,000 | ||||||||||||||||||||||||
| Repayment of accrued interest | 1,100 | ||||||||||||||||||||||||
| June 2025 Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 70,000 | 70,000 | $ 70,000 | ||||||||||||||||||||||
| Debt instrument, interest rate | 4.31% | ||||||||||||||||||||||||
| Maturity date | Jun. 03, 2025 | ||||||||||||||||||||||||
| Debt instrument, redemption, description | On June 3, 2020, the Company issued $70.0 million in aggregate principal amount of 4.310% interest-bearing unsecured notes due June 3, 2025 (the “June 2025 Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement notes offering | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the June 2025 Notes is due semiannually. | ||||||||||||||||||||||||
| Debt instrument, collateral | The June 2025 Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. | ||||||||||||||||||||||||
| June 2025 3-Year Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 50,000 | 50,000 | $ 50,000 | ||||||||||||||||||||||
| Debt instrument, interest rate | 6.00% | ||||||||||||||||||||||||
| Maturity date | Jun. 23, 2025 | ||||||||||||||||||||||||
| Debt instrument, redemption, description | On June 23, 2022, the Company issued $50.0 million in aggregate principal amount of 6.000% interest-bearing unsecured notes due June 23, 2025 (the “June 2025 3-Year Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement notes offering | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the June 2025 3-Year Notes is due semiannually. | ||||||||||||||||||||||||
| Debt instrument, collateral | The June 2025 3-Year Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. | ||||||||||||||||||||||||
| March 2026 A Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 50,000 | 50,000 | $ 50,000 | ||||||||||||||||||||||
| Debt instrument, interest rate | 4.50% | ||||||||||||||||||||||||
| Maturity date | Mar. 04, 2026 | ||||||||||||||||||||||||
| Debt instrument, redemption, description | On November 4, 2020, the Company issued $50.0 million in aggregate principal amount of 4.500% interest-bearing unsecured notes due March 4, 2026 (the “March 2026 A Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement notes offering | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the March 2026 A Notes is due semiannually | ||||||||||||||||||||||||
| Debt instrument, collateral | The March 2026 A Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. | ||||||||||||||||||||||||
| March 2026 B Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 50,000 | 50,000 | $ 50,000 | ||||||||||||||||||||||
| Debt instrument, interest rate | 4.55% | ||||||||||||||||||||||||
| Maturity date | Mar. 04, 2026 | ||||||||||||||||||||||||
| Debt instrument, redemption, description | On March 4, 2021, the Company issued $50.0 million in aggregate principal amount of 4.550% interest-bearing unsecured notes due March 4, 2026 (the “March 2026 B Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement pursuant note offering | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the March 2026 B Notes is due semiannually | ||||||||||||||||||||||||
| Debt instrument, collateral | The March 2026 B Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. | ||||||||||||||||||||||||
| September 2026 Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 325,000 | 325,000 | $ 325,000 | ||||||||||||||||||||||
| Debt instrument, interest rate | 2.625% | ||||||||||||||||||||||||
| Maturity date | Sep. 16, 2026 | ||||||||||||||||||||||||
| Debt instrument, redemption, description | On September 16, 2021, the Company issued $325.0 million in aggregate principal amount of 2.625% interest-bearing unsecured notes due September 16, 2026 (the “September 2026 Notes”), unless repurchased in accordance with the terms of the Seventh Supplemental Indenture, dated September 16, 2021. | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the September 2026 Notes is payable semiannually in arrears on March 16 and September 16 of each year. | ||||||||||||||||||||||||
| Debt instrument, collateral | The September 2026 Notes are general unsecured obligations and rank pari passu, or equally in right of payment, with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. | ||||||||||||||||||||||||
| January 2027 Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 350,000 | 350,000 | $ 350,000 | ||||||||||||||||||||||
| Debt instrument, interest rate | 3.375% | ||||||||||||||||||||||||
| Maturity date | Jan. 20, 2027 | ||||||||||||||||||||||||
| Debt instrument, redemption, description | The Company may redeem some or all of the January 2027 Notes at any time, or from time to time, at the redemption price set forth under the terms of the January 2027 Notes Indenture. | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the January 2027 Notes is payable semiannually in arrears on January 20 and July 20 of each year. | ||||||||||||||||||||||||
| Debt instrument, collateral | The January 2027 Notes are general unsecured obligations and rank pari passu, or equally in right of payment, with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. | ||||||||||||||||||||||||
| 2028 Convertible Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 287,500 | $ 287,500 | 0 | ||||||||||||||||||||||
| Debt instrument, interest rate | 4.75% | ||||||||||||||||||||||||
| Maturity date | Sep. 01, 2028 | ||||||||||||||||||||||||
| Debt instrument, redemption, description | On March 10, 2025, the Company issued $287.5 million in aggregate principal amount of 4.750% interest-bearing convertible unsecured notes due on September 1, 2028 (the "2028 Convertible Notes"), unless previously converted or caused to repurchase the notes in accordance with their terms by the holders of the 2028 Convertible Notes. The Company may not redeem the 2028 Convertible Notes at its option prior to maturity. | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the 2028 Convertible Notes is due semiannually. | ||||||||||||||||||||||||
| Debt instrument, collateral | The 2028 Convertible Notes are unsecured obligations of the Company and rank pari passu, or equally in right of payment, with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. | ||||||||||||||||||||||||
| Initial conversion ratio (in dollars per share) | 0.0465631 | ||||||||||||||||||||||||
| Conversion price (in dollars per share) | $ / shares | $ 21.48 | ||||||||||||||||||||||||
| 2031 Asset-Backed Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 116,845 | 119,475 | $ 150,000 | ||||||||||||||||||||||
| Debt instrument, interest rate | 4.95% | ||||||||||||||||||||||||
| Maturity date | Jul. 20, 2031 | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the 2031 Asset-Backed Notes will be paid, to the extent of funds available. | ||||||||||||||||||||||||
| Repayments of debt | $ 2,600 | 30,500 | |||||||||||||||||||||||
| Loss on extinguishment of debt | 15 | 200 | |||||||||||||||||||||||
| 2031 Asset-Backed Notes | VIE | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Restricted cash | 3,200 | 3,300 | |||||||||||||||||||||||
| 2033 Notes | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 40,000 | 40,000 | $ 40,000 | ||||||||||||||||||||||
| Debt instrument, interest rate | 6.25% | ||||||||||||||||||||||||
| Maturity date | Oct. 30, 2033 | ||||||||||||||||||||||||
| Debt instrument, redemption, description | The Company may redeem some or all of the 2033 Notes at any time, or from time to time, at the redemption price set forth under the terms of the 2033 Notes indenture after October 30, 2023. | ||||||||||||||||||||||||
| Debt instrument, payment terms, description | Interest on the 2033 Notes is payable quarterly in arrears on January 30, April 30, July 30, and October 30 of each year | ||||||||||||||||||||||||
| Debt instrument, collateral | The 2033 Notes trade on the NYSE under the symbol “HCXY.” The 2033 Notes are general unsecured obligations and rank pari passu, or equally in right of payment, with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. | ||||||||||||||||||||||||
| MUFG Bank Facility | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 400,000 | 400,000 | |||||||||||||||||||||||
| MUFG Bank Facility | MUFG Bank Facility | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Maximum borrowing capacity | $ 400,000 | ||||||||||||||||||||||||
| Line of credit facility, description | funded by existing or additional lenders and with the agreement of MUFG Bank and subject to other customary conditions. | ||||||||||||||||||||||||
| Debt instrument, variable interest rate, type [Extensible enumeration] | One Month Secured Overnight Financing Rate Sofr Overnight Index Swap Rate [Member] | ||||||||||||||||||||||||
| Interest rate plus applicable margin adjustment | 2.75% | ||||||||||||||||||||||||
| Line of credit facility, covenant terms | these covenants require the Company to maintain certain financial ratios, including a minimum interest coverage ratio and a minimum tangible net worth with respect to Hercules Funding IV. | ||||||||||||||||||||||||
| MUFG Bank Facility | MUFG Bank Facility | Maximum | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Accordion feature, increase limit | $ 600,000 | ||||||||||||||||||||||||
| SMBC Facility | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | [2],[3] | 475,000 | 475,000 | ||||||||||||||||||||||
| SMBC Facility | Term Loan | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | 25,000 | 25,000 | |||||||||||||||||||||||
| SMBC Facility | SMBC LC Facility | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Maximum borrowing capacity | 175,000 | $ 175,000 | $ 175,000 | ||||||||||||||||||||||
| Line of credit facility, description | Availability under the revolving SMBC Facility will terminate on November 24, 2028, and the outstanding loans under the SMBC Facility will mature on November 26, 2029 | ||||||||||||||||||||||||
| Accordion feature, increase limit | $ 400,000 | ||||||||||||||||||||||||
| Line of credit facility, unused capacity, commitment fee percentage | 0.375% | ||||||||||||||||||||||||
| Line of credit facility, termination date | Feb. 05, 2028 | ||||||||||||||||||||||||
| SMBC Facility | SMBC LC Facility | Term Loan | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Outstanding principal balances | $ 25,000 | ||||||||||||||||||||||||
| Interest rate plus applicable margin adjustment | 2.00% | ||||||||||||||||||||||||
| SMBC Facility | SMBC LC Facility | Minimum | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Interest rate plus applicable margin adjustment | 1.00% | ||||||||||||||||||||||||
| SMBC Facility | SMBC LC Facility | Maximum | |||||||||||||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||||||||||||
| Accordion feature, increase limit | $ 500,000 | ||||||||||||||||||||||||
| Interest rate plus applicable margin adjustment | 2.00% | ||||||||||||||||||||||||
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