XML 63 R50.htm IDEA: XBRL DOCUMENT
v3.22.2.2

Debt - Additional Information (Details) $ in Thousands |  |  |  |  |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jun. 23, 2022 USD ($) | Feb. 22, 2022 USD ($) | Jan. 20, 2022 USD ($) | Sep. 16, 2021 USD ($) | Mar. 04, 2021 USD ($) | Oct. 27, 2020 USD ($) | Sep. 30, 2022 USD ($) | Sep. 30, 2021 USD ($) | Sep. 30, 2022 USD ($) Firm | Sep. 30, 2021 USD ($) | Dec. 31, 2021 USD ($) | Jun. 22, 2022 USD ($) | Feb. 01, 2022 USD ($) shares | Nov. 04, 2020 USD ($) | Jun. 03, 2020 USD ($) | Feb. 05, 2020 USD ($) | Jul. 16, 2019 USD ($) | Sep. 24, 2018 USD ($) | Oct. 23, 2017 USD ($) | Jan. 25, 2017 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  |  |  | $ 2,185,000 |  | $ 2,185,000 |  | $ 1,745,000 |  |  |  |  |  |  |  | $ 150,000 |
Investment Owned At Fair Value |  |  |  |  |  |  | $ 2,825,738 |  | $ 2,825,738 |  | 2,434,522 |  |  |  |  |  |  |  |  |
Debt instrument, interest rate |  |  |  |  |  |  | 4.625% |  | 4.625% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  |  |  |  |  |  |  | Oct. 23, 2022 |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, redemption, description |  |  |  |  |  |  |  |  | On October 23, 2017, the Company issued $150.0 million in aggregate principal amount of 4.625% interest-bearing unsecured notes that mature on October 23, 2022 (the “2022 Notes”), unless repurchased in accordance with their terms |  |  |  |  |  |  |  |  |  |  |
Repayment of debt |  | $ 150,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest payable |  | 2,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on extinguishment of debt |  |  |  |  |  |  | $ 0 | $ (1,702) | $ (3,686) | $ (1,702) |  |  |  |  |  |  |  |  |  |
Restricted cash (amounts related to a VIE $8,346 and $0, respectively) |  |  |  |  |  |  | 8,346 | $ 13,509 | $ 8,346 | $ 13,509 | 3,150 |  |  |  |  |  |  |  |  |
Line of credit facility, termination date |  |  |  |  |  |  |  |  | Nov. 09, 2026 |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Description |  |  |  |  |  |  |  |  | Availability under the SMBC Facility will terminate on November 7, 2025, and the outstanding loans under the SMBC Facility will mature on November 9, 2026. |  |  |  |  |  |  |  |  |  |  |
Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restricted cash (amounts related to a VIE $8,346 and $0, respectively) |  |  |  |  |  |  | 8,346 |  | $ 8,346 |  | 0 |  |  |  |  |  |  |  |  |
MUFG Bank Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Covenant Terms |  |  |  |  |  |  |  |  | these covenants require the Company to maintain certain financial ratios, including a minimum interest coverage ratio with respect to Hercules Funding IV and a minimum tangible net worth in an amount that is in excess of $723.0 million. |  |  |  |  |  |  |  |  |  |  |
Line of credit facility, termination date |  |  |  |  |  |  |  |  | Feb. 22, 2024 |  |  |  |  |  |  |  |  |  |  |
Minimum tangible net worth amount |  |  |  |  |  |  | 723,000 |  | $ 723,000 |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  | 545,000 |  | $ 545,000 |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Description |  |  |  |  |  |  |  |  | The MUFG Bank Facility contains an accordion feature, in which the Company can increase the credit line up to an aggregate of $600.0 million, funded by existing or additional lenders and with the agreement of MUFG Bank and subject to other customary conditions. |  |  |  |  |  |  |  |  |  |  |
MUFG Bank Facility | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  | 600,000 |  | $ 600,000 |  |  |  |  |  |  |  |  |  |  |
MUFG Bank Facility | One-month interest period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate plus applicable margin adjustment |  |  |  |  |  |  |  |  | 2.60% |  |  |  |  |  |  |  |  |  |  |
MUFG Bank Facility | Three-month interest period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate plus applicable margin adjustment |  |  |  |  |  |  |  |  | 2.65% |  |  |  |  |  |  |  |  |  |  |
MUFG Bank Facility | Lender [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  |  |  |  |  | 400,000 |  |  |  |  |  |  |  |  |
S M B C Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of credit facility, termination date |  |  |  |  |  |  |  |  | Nov. 07, 2025 |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  | 225,000 |  | $ 225,000 |  | 100,000 |  |  |  |  |  |  |  |  |
Line of Credit Facility, Description |  |  |  |  |  |  |  |  | the SMBC Facility provides for the issuance of letters of credit on the account of the Company or its designee in U.S. dollars and certain agreed upon foreign currencies in an aggregate face amount not to exceed $15.0 million. |  |  |  |  |  |  |  |  |  |  |
Line of credit facility, unused capacity, commitment fee percentage |  |  |  |  |  |  |  |  | 0.375% |  |  |  |  |  |  |  |  |  |  |
S M B C Facility [Member] | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate plus applicable margin adjustment |  |  |  |  |  |  |  |  | 0.875% |  |  |  |  |  |  |  |  |  |  |
S M B C Facility [Member] | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate plus applicable margin adjustment |  |  |  |  |  |  |  |  | 2.00% |  |  |  |  |  |  |  |  |  |  |
Credit Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt average amount outstanding |  |  |  |  |  |  |  |  | $ 115,600 |  | $ 28,800 |  |  |  |  |  |  |  |  |
Line of credit interest rate |  |  |  |  |  |  |  |  | 3.70% |  | 2.54% |  |  |  |  |  |  |  |  |
Debt Issuance Cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on extinguishment of debt |  | (300) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Prepayment Fees |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on extinguishment of debt |  | $ (3,300) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Foreign Currency Borrowing Member | S M B C Facility [Member] | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  | 15,000 |  | $ 15,000 |  |  |  |  |  |  |  |  |  |  |
2022 Convertible Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  |  |  | $ 0 |  | $ 0 |  | $ 230,000 |  |  |  |  |  |  |  |  | $ 230,000
Debt instrument, interest rate |  |  |  |  |  |  | 4.375% |  | 4.375% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  |  |  |  |  |  |  | Feb. 01, 2022 |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, redemption, description |  |  |  |  |  |  |  |  | On January 25, 2017, the Company issued $230.0 million in aggregate principal amount of 4.375% interest-bearing unsecured notes due on February 1, 2022 (the “2022 Convertible Notes”), unless previously converted or caused to repurchase the notes in accordance with their terms by the holders of the 2022 Convertible Notes |  |  |  |  |  |  |  |  |  |  |
Repayment of debt |  |  |  |  |  |  |  |  |  |  |  |  | $ 230,000 |  |  |  |  |  |  |
Interest payable |  |  |  |  |  |  |  |  |  |  |  |  | $ 5,000 |  |  |  |  |  |  |
Debt instrument, payment terms, description |  |  |  |  |  |  |  |  | Interest on the 2022 Convertible Notes is due semiannually in arrears on February 1 and August 1 of each year |  |  |  |  |  |  |  |  |  |  |
Convertible Debt Redemption Shares Issued on Redemption | shares |  |  |  |  |  |  |  |  |  |  |  |  | 981,169 |  |  |  |  |  |  |
2022 Convertible Notes | Additional Face Amount [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 30,000
July 2024 Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 105,000 |  |  |
Debt instrument, interest rate |  |  |  |  |  |  | 4.77% |  | 4.77% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  |  |  |  |  |  |  | Jul. 16, 2024 |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, redemption, description |  |  |  |  |  |  |  |  | On July 16, 2019, the Company issued $105.0 million in aggregate principal amount of 4.77% 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 is due semiannually |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Collateral |  |  |  |  |  |  |  |  | The July 2024 Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. |  |  |  |  |  |  |  |  |  |  |
February 2025 Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 50,000 |  |  |  |
Debt instrument, interest rate |  |  |  |  |  |  | 4.28% |  | 4.28% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  |  |  |  |  |  |  | Feb. 05, 2025 |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, redemption, description |  |  |  |  |  |  |  |  | On February 5, 2020, the Company issued $50.0 million in aggregate principal amount of 4.28% 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 is due semiannually |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Collateral |  |  |  |  |  |  |  |  | The February 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 Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 70,000 |  |  |  |  |
Debt instrument, interest rate |  |  |  |  |  |  | 4.31% |  | 4.31% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  |  |  |  |  |  |  | Jun. 03, 2025 |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, redemption, description |  |  |  |  |  |  |  |  | On June 3, 2020, the Company issued $70.0 million in aggregate principal amount of 4.31% 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] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount | $ 50,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate |  |  |  |  |  |  | 6.00% |  | 6.00% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Maturity Date | Jun. 23, 2025 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, redemption, description |  |  |  |  |  |  |  |  | On June 23, 2022, the Company issued $50.0 million in aggregate principal amount of 6.00% 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] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 50,000 |  |  |  |  |  |
Debt instrument, interest rate |  |  |  |  |  |  | 4.50% |  | 4.50% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  |  |  |  |  |  |  | Mar. 04, 2026 |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, redemption, description |  |  |  |  |  |  |  |  | On November 4, 2020, the Company issued $50.0 million in aggregate principal amount of 4.5% 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] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  | $ 50,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate |  |  |  |  |  |  | 4.55% |  | 4.55% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  |  |  |  |  |  |  | Mar. 04, 2026 |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, redemption, description |  |  |  |  |  |  |  |  | On March 4, 2021, the Company issued $50.0 million in aggregate principal amount of 4.55% 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 |  |  |  |  |  |  |  |  |  |  |
Net proceeds from sale of Notes |  |  |  |  | 49,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Debt Issuance Cost |  |  |  |  | $ 500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  | $ 325,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate |  |  |  |  |  |  | 2.625% |  | 2.625% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  |  |  |  |  |  |  | Sep. 16, 2026 |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, redemption, description |  |  |  |  |  |  |  |  | The Company may redeem some or all of the September 2026 Notes at any time, or from time to time, at the redemption price set forth under the terms of the September 2026 Notes Indenture. |  |  |  |  |  |  |  |  |  |  |
Debt instrument, payment terms, description |  |  |  |  |  |  |  |  | Interest on the September 2026 Notes is payable semi-annually in arrears on March 16 and September 16 of each year, commencing on March 16, 2022 |  |  |  |  |  |  |  |  |  |  |
Net proceeds from sale of Notes |  |  |  | 320,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Debt Issuance Cost |  |  |  | 4,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Discount On Issuance |  |  |  | $ 800 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  | $ 350,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate |  |  |  |  |  |  | 3.375% |  | 3.375% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument 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 semi-annually in arrears on January 20 and July 20 of each year, commencing on July 20, 2022 |  |  |  |  |  |  |  |  |  |  |
Net proceeds from sale of Notes |  |  | 343,400 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Debt Issuance Cost |  |  | 4,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Discount On Issuance |  |  | $ 2,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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. |  |  |  |  |  |  |  |  |  |  |
2031 Asset-Backed Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  |  |  |  |  |  |  |  | $ 150,000 |  |  |  |  |  |  |  |
Debt instrument, interest rate |  |  |  |  |  |  | 4.95% |  | 4.95% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument 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. |  |  |  |  |  |  |  |  |  |  |
2031 Asset-Backed Notes | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restricted cash (amounts related to a VIE $8,346 and $0, respectively) |  |  |  |  |  |  | $ 8,300 |  | $ 8,300 |  | $ 0 |  |  |  |  |  |  |  |  |
2033 Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 40,000 |  |
Debt instrument, interest rate |  |  |  |  |  |  | 6.25% |  | 6.25% |  |  |  |  |  |  |  |  |  |  |
Debt Instrument 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. |  |  |  |  |  |  |  |  |  |  |
HC IV |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
License term |  |  |  |  |  | 10 years |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, license description |  |  |  |  |  |  |  |  | HC IV received its license to operate as a SBIC on October 27, 2020. The license has a 10-year term. |  |  |  |  |  |  |  |  |  |  |
Regulatory capital commitment amount |  |  |  |  |  | $ 87,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Face Amount |  |  |  |  |  |  | $ 175,000 |  | $ 175,000 |  |  |  |  |  |  |  |  |  |  |
Investments held by number of companies | Firm |  |  |  |  |  |  |  |  | 18 |  |  |  |  |  |  |  |  |  |  |
Investment Owned At Fair Value |  |  |  |  |  |  | $ 277,100 |  | $ 277,100 |  |  |  |  |  |  |  |  |  |  |
Percentage of total investment portfolio |  |  |  |  |  |  | 9.80% |  | 9.80% |  |  |  |  |  |  |  |  |  |  |
Tangible Assets |  |  |  |  |  |  | $ 287,600 |  | $ 287,600 |  |  |  |  |  |  |  |  |  |  |
Percentage of total assets held |  |  |  |  |  |  | 9.80% |  | 9.80% |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  | $ 175,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
HC IV | SBA Commitment Fee [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt issuance cost |  |  |  |  |  |  | $ 1,750 |  | $ 1,750 |  |  |  |  |  |  |  |  |  |  |
HC IV | SBA Facility Fee [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt issuance cost |  |  |  |  |  |  | $ 4,200 |  | $ 4,200 |  |  |  |  |  |  |  |  |  |  |

X
- Definition Aggregate debt issuance cost + References No definition available. + Details
Name: | htgc_AggregateDebtIssuanceCost
Namespace Prefix: | htgc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Aggregate discount on issuance + References No definition available. + Details
Name: | htgc_AggregateDiscountOnIssuance
Namespace Prefix: | htgc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Convertible Debt Redemption Shares Issued on Redemption. + References No definition available. + Details
Name: | htgc_ConvertibleDebtRedemptionSharesIssuedOnRedemption
Namespace Prefix: | htgc_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Debt Instrument License Description + References No definition available. + Details
Name: | htgc_DebtInstrumentLicenseDescription
Namespace Prefix: | htgc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Investments held by number of companies. + References No definition available. + Details
Name: | htgc_InvestmentsHeldByNumberOfCompanies
Namespace Prefix: | htgc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition License term. + References No definition available. + Details
Name: | htgc_LicenseTerm
Namespace Prefix: | htgc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of assets held. + References No definition available. + Details
Name: | htgc_PercentageOfAssetsHeld
Namespace Prefix: | htgc_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of investment portfolio. + References No definition available. + Details
Name: | htgc_PercentageOfInvestmentPortfolio
Namespace Prefix: | htgc_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Regulatory capital commitment amount. + References No definition available. + Details
Name: | htgc_RegulatoryCapitalCommitmentAmount
Namespace Prefix: | htgc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Tangible assets held. + References No definition available. + Details
Name: | htgc_TangibleAssets
Namespace Prefix: | htgc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Discussion of whether the debt instrument is secured or unsecured, and, if secured, a description of the collateral and guarantees required or provided. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (d) -URI https://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentCollateral
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI https://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 50 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69C -URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69B -URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (d) -URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258 + Details
Name: | us-gaap_DebtInstrumentMaturityDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of the payment terms of the debt instrument (for example, whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(3)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentPaymentTerms
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of debt redemption features under terms of the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph e -URI https://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentRedemptionDescription
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of the original debt instrument that was repurchased. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28555-108399 + Details
Name: | us-gaap_DeferredFinanceCostsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 4 -URI https://asc.fasb.org/extlink&oid=126972273&loc=d3e12355-112629 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 2 -URI https://asc.fasb.org/extlink&oid=126972273&loc=d3e12317-112629 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585 + Details
Name: | us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of interest payable on debt, including, but not limited to, trade payables. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.15(5)) -URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.15(a)) -URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910 + Details
Name: | us-gaap_InterestPayableCurrentAndNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section 50 -Paragraph 6 -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=99383244&loc=d3e12121-115841 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 5D -Subparagraph (SX 210.12-13D(Column C)) -URI https://asc.fasb.org/extlink&oid=122147990&loc=SL120429264-123010 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-12B(Column C)) -URI https://asc.fasb.org/extlink&oid=122147990&loc=d3e611197-123010 + Details
Name: | us-gaap_InvestmentOwnedAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Average amount borrowed under the credit facility during the period. + References No definition available. + Details
Name: | us-gaap_LineOfCreditFacilityAverageOutstandingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Description of the conditions for borrowing under the credit facility including the nature of any restrictions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityCovenantTerms
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of the terms of a credit facility arrangement. Terms typically include interest rate, collateral required, guarantees required, repayment requirements, and restrictions on use of assets and activities of the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityDescription
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the credit facility terminates, in YYYY-MM-DD format. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition The effective interest rate during the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility. + References No definition available. + Details
Name: | us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of minimum net worth required for mortgage banking as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=6490092&loc=d3e47080-110998 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998 + Details
Name: | us-gaap_MinimumNetWorthRequiredForCompliance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The cash inflow associated with the sale of a borrowing supported by a written promise to pay an obligation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfNotesReceivable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of cash restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(1)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 8 -URI https://asc.fasb.org/extlink&oid=126999549&loc=SL98516268-108586 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(1)(a)) -URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(2)) -URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910 + Details
Name: | us-gaap_RestrictedCash
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=htgc_MUFGBankFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=htgc_OneMonthSecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=htgc_ThreeMonthSecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=htgc_LenderMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=htgc_SMBCFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=htgc_DebtIssuanceCostMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=htgc_PrepaymentFeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_ForeignCurrencyBorrowingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_TwoThousandTwentyTwoConvertibleNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=htgc_AdditionalFaceAmountMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_July2024NotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_February2025NotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_June2025NotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_June20253YearNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_March2026ANotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_March2026BNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_September2026NotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_January2027NotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_AssetBackedNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=htgc_NotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=htgc_HerculesCapitalFourLPMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=htgc_SbaCommitmentFeeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=htgc_SbaFacilityFeeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |