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Investments - Geographic Investment (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2023 | Dec. 31, 2022
Schedule of Investments [Line Items] |  |
Cost | $ 9,669,106 | $ 9,657,872
Fair Value | $ 9,626,202 | $ 9,617,248
Fair Value as % of Net Assets | 229.72% | 231.24%
Investment Owned, At Fair Value | Investment Type Concentration Risk |  |
Schedule of Investments [Line Items] |  |
% of Total Investments at Fair Value | 100.00% | 100.00%
United States |  |
Schedule of Investments [Line Items] |  |
Cost | $ 8,983,241 | $ 8,934,926
Fair Value | $ 8,929,026 | $ 8,893,051
Fair Value as % of Net Assets | 213.08% | 213.83%
United States | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |
Schedule of Investments [Line Items] |  |
% of Total Investments at Fair Value | 92.76% | 92.47%
Canada |  |
Schedule of Investments [Line Items] |  |
Cost | $ 470,555 | $ 510,599
Fair Value | $ 486,555 | $ 520,368
Fair Value as % of Net Assets | 11.61% | 12.51%
Canada | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |
Schedule of Investments [Line Items] |  |
% of Total Investments at Fair Value | 5.05% | 5.41%
Europe |  |
Schedule of Investments [Line Items] |  |
Cost | $ 215,310 | $ 212,347
Fair Value | $ 210,621 | $ 203,829
Fair Value as % of Net Assets | 5.03% | 4.90%
Europe | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |
Schedule of Investments [Line Items] |  |
% of Total Investments at Fair Value | 2.19% | 2.12%

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