v3.26.1
Debt - Additional Information (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Mar. 09, 2026
Jan. 28, 2026
Sep. 09, 2025
Sep. 11, 2024
Mar. 11, 2024
Nov. 24, 2020
Feb. 10, 2020
Line Of Credit Facility [Line Items]                    
Debt, Current borrowing capacity $ 2,895,000   $ 2,995,000              
Deferred financing costs 12,444   13,245              
Carrying value [1] $ 1,898,158   1,874,620              
2025 Notes                    
Line Of Credit Facility [Line Items]                    
Aggregate principal amount                   $ 360,000
Interest rate                   3.75%
Debt Instrument, Maturity Date, Description The 2025 Notes bore interest at a rate of 3.750% per year, payable semi-annually in arrears on February 10 and August 10 of each year. The 2025 Notes matured and were fully repaid on February 10, 2025, in accordance with their terms, using proceeds from the Revolving Credit Facility.                  
Carrying value $ 0   0              
2026 Notes                    
Line Of Credit Facility [Line Items]                    
Aggregate principal amount     500,000           $ 500,000  
Interest rate                 2.875%  
Debt Instrument, Maturity Date, Description The 2026 Notes bore interest at a rate of 2.875% per year, payable semi-annually in arrears on January 15 and July 15 of each year. The 2026 Notes matured and were fully repaid on January 15, 2026, in accordance with their terms, using proceeds from the Revolving Credit Facility.                  
Carrying value     499,921              
2027 Notes                    
Line Of Credit Facility [Line Items]                    
Aggregate principal amount $ 400,000   400,000         $ 400,000    
Interest rate             6.375% 6.375%    
Debt Instrument, Maturity Date, Description The 2027 Notes bear interest at a rate of 6.375% per year, payable semi-annually in arrears on March 11 and September 11 of each year. The 2027 Notes will mature on March 11, 2027 and may be redeemed in whole or in part at the Company’s option at any time or from time to time at the redemption prices set forth in the indenture.                  
Carrying value $ 396,689   397,333              
2029 Notes                    
Line Of Credit Facility [Line Items]                    
Aggregate principal amount $ 400,000       $ 400,000          
Interest rate         5.10%          
Debt Instrument, Maturity Date, Description The 2029 Notes bear interest at a rate of 5.100% per year, payable semi-annually in arrears on January 28 and July 28 of each year, commencing on July 28, 2026. The 2029 Notes will mature on January 28, 2029 and may be redeemed in whole or in part at the Company's option at any time or from time to time at the redemption prices set forth in the indenture.                  
Carrying value $ 391,468                  
2030 Notes                    
Line Of Credit Facility [Line Items]                    
Aggregate principal amount $ 400,000   400,000     $ 400,000        
Interest rate       5.65%   5.65%        
Debt Instrument, Maturity Date, Description The 2030 Notes bear interest at a rate of 5.650% per year, payable semi-annually in arrears on March 9 and September 9 of each year. The 2030 Notes will mature on September 9, 2030 and may be redeemed in whole or in part at the Company’s option at any time or from time to time at the redemption prices set forth in the indenture.                  
Carrying value $ 389,502   391,616              
Revolving Credit Facility                    
Line Of Credit Facility [Line Items]                    
Weighted average interest rate 5.55% 6.37%                
Average outstanding balance $ 739,757 $ 891,971                
Debt, Current borrowing capacity [2] 1,695,000 [1]   1,695,000              
Maximum borrowing capacity $ 2,542,500                  
Revolving credit facility interest rate description Borrowings denominated in USD, including amounts drawn in respect of letters of credit, bear interest (at the Company’s election) of either (i) Term SOFR plus a margin of either (x) 2.00%, (y) 1.875% (subject to maintenance of certain long-term corporate debt ratings) or (z) 1.75% (subject to certain gross borrowing base conditions), in each case, plus an additional 0.10% credit adjustment spread or (ii) an alternative base rate, which is the highest of (a) zero, (b) the highest of (i) the Prime Rate in effect on such day, (ii) the Federal Funds Effective Rate for such day plus 1/2 of 1.00% and (iii) the rate per annum equal to (x) the greater of (A) Term SOFR for an interest period of one (1) month and (B) zero plus (y) 1.00%, plus a margin of either (x) 1.00%, (y) 0.875% (subject to maintenance of certain long-term corporate debt ratings) or (z) 0.75% (subject to certain gross borrowing base conditions). Borrowings denominated in non-USD bear interest of the applicable term benchmark rate or the applicable risk-free rate (the “RFR rate”) plus a margin of either 2.00%, 1.875% or 1.75% (subject to the conditions applicable to borrowings denominated in USD that bear interest based on the applicable term benchmark rate or the applicable RFR rate), plus, (i) in the case of borrowings denominated in GBP only, an additional 0.1193% credit adjustment spread, (ii) in the case of borrowings denominated in CHF only, an additional 0.0031% and (iii) in the case of borrowings denominated in CAD only, an additional 0.29547% (one-month interest period) or an additional 0.32138% (three-month interest period) credit adjustment spread. Borrowings from certain lenders, which hold approximately 84% of total lending commitments (the "Extending Lenders"), bear interest at the applicable rates described above less 0.10%. With respect to borrowings denominated in USD, the Company may elect either Term SOFR, or an alternative base rate at the time of borrowing, and such borrowings may be converted from one benchmark to another at any time, subject to certain conditions. Interest is payable in arrears on the applicable interest payment date as specified therein. The Company pays a fee of 0.375% per annum on committed but undrawn amounts under the Revolving Credit Facility, payable quarterly in arrears. Any amounts borrowed under the Revolving Credit Facility with respect to the Extending Lenders, will mature, and all accrued and unpaid interest will be due and payable, on June 24, 2030. Any amounts borrowed under the Revolving Credit Facility, will mature, and all accrued and unpaid interest will be due and payable, with respect to certain remaining lenders, on May 5, 2027, and with respect to other remaining lenders, on October 18, 2028.                  
Line of credit facility, commitment fee percentage 0.375%                  
Cost incurred in obtaining revolving credit facility $ 38,116                  
Unamortized deferred financing costs 12,444   13,245              
Carrying value [1],[2] $ 720,499   $ 585,750              
Revolving Credit Facility | Borrowings denominated in USD                    
Line Of Credit Facility [Line Items]                    
Additional credit adjustment spread 0.10%                  
Revolving Credit Facility | Borrowings denominated in Pound Sterling (GBP)                    
Line Of Credit Facility [Line Items]                    
Additional credit adjustment spread 0.1193%                  
Revolving Credit Facility | Borrowings denominated in CHF                    
Line Of Credit Facility [Line Items]                    
Additional credit adjustment spread 0.0031%                  
Revolving Credit Facility | Minimum                    
Line Of Credit Facility [Line Items]                    
Asset coverage ratio 150.00%                  
Asset coverage ratio with respect to consolidated assets 200.00%                  
Revolving Credit Facility | Lenders Hold 84% of Total Lending Commitments                    
Line Of Credit Facility [Line Items]                    
Revolving credit facility accrued and unpaid interest due and payable date Jun. 24, 2030                  
Revolving Credit Facility | Lenders Hold 84% of Total Lending Commitments | Borrowings denominated in USD                    
Line Of Credit Facility [Line Items]                    
Additional credit adjustment spread 0.10%                  
Revolving Credit Facility | Certain Remaining Lenders                    
Line Of Credit Facility [Line Items]                    
Revolving credit facility accrued and unpaid interest due and payable date May 05, 2027                  
Revolving Credit Facility | Other Lenders                    
Line Of Credit Facility [Line Items]                    
Revolving credit facility accrued and unpaid interest due and payable date Oct. 18, 2028                  
Revolving Credit Facility | One-month Canadian Dollars | Borrowings denominated in Canadian Dollars                    
Line Of Credit Facility [Line Items]                    
Additional credit adjustment spread 0.29547%                  
Revolving Credit Facility | Three-month Canadian Dollars | Borrowings denominated in Canadian Dollars                    
Line Of Credit Facility [Line Items]                    
Additional credit adjustment spread 0.32138%                  
Debt                    
Line Of Credit Facility [Line Items]                    
Asset coverage ratio requirement, description Investment Company Act, is at least 150% after such borrowing (if certain requirements are met). As of March 31, 2026 and December 31, 2025, the Company’s asset coverage ratio based on the aggregate amount outstanding of senior securities was 171% and 175%.                  
Asset coverage ratio 171.00%   175.00%              
Weighted average interest rate 5.75%   5.36%              
Average outstanding balance $ 1,897,534   $ 1,860,251              
Maximum borrowing capacity $ 2,542,500                  
[1] The carrying value is presented net of the unamortized debt issuance costs and includes the cumulative hedging adjustments for those borrowings that are designated in a fair value hedging relationship, as applicable.
[2] Provides, under certain circumstances, a total borrowing capacity of $2,542,500. The Company may borrow amounts in USD or certain other permitted currencies. Debt outstanding denominated in currencies other than USD has been converted to USD using the applicable foreign currency exchange rate as of the applicable reporting date. As of March 31, 2026, the Company had outstanding borrowings denominated in USD of $623,674, in EUR of EUR 13,700, in GBP of GBP 17,450, in CAD of CAD 57,020 and in AUD of AUD 24,500. As of December 31, 2025, the Company had outstanding borrowings denominated in USD of $489,674, in EUR of EUR 13,700, in GBP of GBP 18,950, in CAD of CAD 52,270 and in AUD of AUD 24,500.