Annual report pursuant to Section 13 and 15(d)

Fair Value of Financial Instruments - Schedule of Reconciliation of Changes for All Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details)

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Fair Value of Financial Instruments - Schedule of Reconciliation of Changes for All Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Roll Forward]    
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Net realized gain (loss) Net realized gain (loss)
Significant Unobservable Inputs (Level 3) | Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Roll Forward]    
Beginning Balance $ 3,185,103 $ 2,882,285
Net Realized Gains (Losses) (65,781) (13,021)
Net Change in Unrealized Appreciation (Depreciation) (10,738) 19,550
Purchases 1,494,274 1,289,369
Sales (22,693) (2,632)
Repayments (965,924) (990,448)
Gross Transfers into Level 3 (2,323) (39,979)
Gross Transfers out of Level 3 (2,605) (39,979)
Ending Balance 3,613,959 3,185,103
Significant Unobservable Inputs (Level 3) | Recurring | Accounts Payable and Accrued Liabilities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Roll Forward]    
Beginning Balance 0  
Net Realized Gains (Losses) (10,938)  
Net Change in Unrealized Appreciation (Depreciation) 11,179  
Purchase 1,870  
Sales 1,353  
Repayments 0  
Gross Transfers into Level 3 1,770  
Gross Transfers out of Level 3 0  
Ending Balance 1,012 0
Significant Unobservable Inputs (Level 3) | Recurring | Preferred Stock    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Roll Forward]    
Beginning Balance 53,038 41,488
Net Realized Gains (Losses) (711) (3,441)
Net Change in Unrealized Appreciation (Depreciation) (5,709) (1,123)
Purchases 4,753 2,851
Sales 0 0
Repayments 0 0
Gross Transfers into Level 3 (2,431) (13,263)
Gross Transfers out of Level 3 0 0
Ending Balance 53,802 53,038
Significant Unobservable Inputs (Level 3) | Recurring | Common Stock    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Roll Forward]    
Beginning Balance 41,790 25,059
Net Realized Gains (Losses) (1,453) 0
Net Change in Unrealized Appreciation (Depreciation) (1,506) 11,325
Purchases 4,100 6,000
Sales 0 (594)
Repayments 0 0
Gross Transfers into Level 3 (1,662) 0
Gross Transfers out of Level 3 0 0
Ending Balance 44,593 41,790
Significant Unobservable Inputs (Level 3) | Recurring | Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Roll Forward]    
Beginning Balance 22,088 19,419
Net Realized Gains (Losses) (648) (4,295)
Net Change in Unrealized Appreciation (Depreciation) (702) 4,825
Purchases 3,914 3,894
Sales (2,829) (1,755)
Repayments 0 0
Gross Transfers into Level 3 0 0
Gross Transfers out of Level 3 0 0
Ending Balance 21,823 22,088
Significant Unobservable Inputs (Level 3) | Recurring | Senior Secured Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Roll Forward]    
Beginning Balance 2,987,577 2,741,388
Net Realized Gains (Losses) (52,120) (5,350)
Net Change in Unrealized Appreciation (Depreciation) (21,146) 17,277
Purchases 1,475,032 1,264,689
Sales 0 0
Repayments (965,924) (990,448)
Gross Transfers into Level 3 0 0
Gross Transfers out of Level 3 (4,375) (39,979)
Ending Balance 3,419,044 2,987,577
Significant Unobservable Inputs (Level 3) | Recurring | Unsecured Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Roll Forward]    
Beginning Balance 69,722 54,056
Net Realized Gains (Losses) 0 0
Net Change in Unrealized Appreciation (Depreciation) 1,277 4,268
Purchases 4,558 11,398
Sales 0 0
Repayments 0 0
Gross Transfers into Level 3 0 0
Gross Transfers out of Level 3 0 0
Ending Balance 75,557 69,722
Significant Unobservable Inputs (Level 3) | Recurring | Escrow and Other Investment Receivables    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Roll Forward]    
Beginning Balance 10,888 875
Net Realized Gains (Losses) 89 65
Net Change in Unrealized Appreciation (Depreciation) 5,869 (17,022)
Purchases 47 537
Sales (18,511) (283)
Repayments 0 0
Gross Transfers into Level 3 0 (26,716)
Gross Transfers out of Level 3 1,770 0
Ending Balance $ 152 $ 10,888
HTGC Debt And Equity Securities Realized Gain Loss    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Roll Forward]    
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Total net change in unrealized appreciation (depreciation) Total net change in unrealized appreciation (depreciation)