Quarterly report pursuant to Section 13 or 15(d)

Investments - Schedule of Fair Value Portfolio By Industry Sector (Details)

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Investments - Schedule of Fair Value Portfolio By Industry Sector (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2024
Dec. 31, 2023
Schedule Of Investments [Line Items]    
Investments at Fair Value $ 3,571,641 $ 3,248,046
Industry Sector Concentration Risk | Drug Discovery & Development    
Schedule Of Investments [Line Items]    
Investments at Fair Value 1,223,365 1,257,699
Industry Sector Concentration Risk | Software    
Schedule Of Investments [Line Items]    
Investments at Fair Value 833,917 764,985
Industry Sector Concentration Risk | Consumer & Business Services    
Schedule Of Investments [Line Items]    
Investments at Fair Value 537,431 525,973
Industry Sector Concentration Risk | Healthcare Services, Other    
Schedule Of Investments [Line Items]    
Investments at Fair Value 480,002 300,079
Industry Sector Concentration Risk | Communications & Networking    
Schedule Of Investments [Line Items]    
Investments at Fair Value 29,482 29,400
Industry Sector Concentration Risk | Diversified Financial Services    
Schedule Of Investments [Line Items]    
Investments at Fair Value 111,526 114,722
Industry Sector Concentration Risk | Information Services    
Schedule Of Investments [Line Items]    
Investments at Fair Value 128,282 126,605
Industry Sector Concentration Risk | Manufacturing Technology    
Schedule Of Investments [Line Items]    
Investments at Fair Value 8,486 11,006
Industry Sector Concentration Risk | Biotechnology Tools    
Schedule Of Investments [Line Items]    
Investments at Fair Value 50,351 48,381
Industry Sector Concentration Risk | Electronics & Computer Hardware    
Schedule Of Investments [Line Items]    
Investments at Fair Value 76,014 20,324
Industry Sector Concentration Risk | Media/Content/Info    
Schedule Of Investments [Line Items]    
Investments at Fair Value 12,084 12,704
Industry Sector Concentration Risk | Sustainable and Renewable Technology    
Schedule Of Investments [Line Items]    
Investments at Fair Value 21,052 9,581
Industry Sector Concentration Risk | Consumer & Business Products    
Schedule Of Investments [Line Items]    
Investments at Fair Value 2,676 2,589
Industry Sector Concentration Risk | Semiconductors    
Schedule Of Investments [Line Items]    
Investments at Fair Value 998 1,205
Industry Sector Concentration Risk | Medical Devices & Equipment    
Schedule Of Investments [Line Items]    
Investments at Fair Value 55,332 22,096
Industry Sector Concentration Risk | Surgical Devices    
Schedule Of Investments [Line Items]    
Investments at Fair Value 622 676
Industry Sector Concentration Risk | Drug Delivery    
Schedule Of Investments [Line Items]    
Investments at Fair Value 21 21
Industry Sector Concentration Risk | Total Industry Sectors    
Schedule Of Investments [Line Items]    
Investments at Fair Value $ 3,571,641 $ 3,248,046
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Drug Discovery & Development    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 34.30% 38.70%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Software    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 23.40% 23.60%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Consumer & Business Services    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 15.10% 16.20%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Healthcare Services, Other    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 13.40% 9.30%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Communications & Networking    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 0.80% 0.90%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Diversified Financial Services    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 3.10% 3.50%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Information Services    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 3.60% 3.90%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Manufacturing Technology    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 0.20% 0.30%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Biotechnology Tools    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 1.40% 1.50%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Electronics & Computer Hardware    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 2.10% 0.60%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Media/Content/Info    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 0.30% 0.40%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Sustainable and Renewable Technology    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 0.60% 0.30%
Industry Sector Concentration Risk | Industry Sub Sector Investments Benchmark | Consumer & Business Products    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 0.10% 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 | 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 | Surgical Devices    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 0.00% 0.00%
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 | Total Industry Sectors    
Schedule Of Investments [Line Items]    
Percentage of Total Portfolio 100.00% 100.00%