Income Taxes - Narrative (Details) - USD ($) |
3 Months Ended | 12 Months Ended | 26 Months Ended | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Aug. 26, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
Aug. 31, 2026 |
Aug. 31, 2025 |
Aug. 31, 2024 |
Aug. 31, 2025 |
Jun. 30, 2026 |
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| Income Taxes [Line Items] | |||||||||||
| Investment company, distributable earnings (loss), accumulated ordinary income | $ 0 | ||||||||||
| Investment company, distributable earnings (loss), accumulated long-term capital gain | 0 | ||||||||||
| Investment company, distributable earnings (loss), accumulated capital loss carryforward | 784,995,000 | ||||||||||
| Cost basis of investments for tax purposes | $ 6,025,665,000 | $ 6,367,797,000 | |||||||||
| Net unrealized loss | (81,188,000) | (25,239,000) | |||||||||
| Unrealized gains | 1,193,882,000 | 1,263,482,000 | |||||||||
| Unrealized losses | 1,275,070,000 | 1,288,721,000 | |||||||||
| Ordinary income | 141,699,000 | $ 189,162,000 | $ 227,508,000 | ||||||||
| Return of capital | $ 10,394,000 | $ 10,170,000 | [1] | 105,541,000 | $ 69,913,000 | $ 71,414,000 | |||||
| Retained Earnings (Accumulated Deficit) | 1,253,880,000 | 1,496,198,000 | 1,387,494,000 | ||||||||
| Reclassification, Adjustment | |||||||||||
| Income Taxes [Line Items] | |||||||||||
| Retained Earnings (Accumulated Deficit) | 59,743,000 | ||||||||||
| Scenario, Plan | |||||||||||
| Income Taxes [Line Items] | |||||||||||
| Ordinary income | $ 360,488,000 | ||||||||||
| Retained Earnings (Accumulated Deficit) | $ 1,194,137,000 | ||||||||||
| Distributions in excess of earnings | |||||||||||
| Income Taxes [Line Items] | |||||||||||
| Reclassification of distributions from capital, increase (decrease) | $ (10,170,000) | (55,000) | $ (97,000) | ||||||||
| Accumulated Realized Losses | |||||||||||
| Income Taxes [Line Items] | |||||||||||
| Reclassification of distributions from capital, increase (decrease) | 17,799,000 | 16,243,000 | |||||||||
| Paid-in capital in excess of par | |||||||||||
| Income Taxes [Line Items] | |||||||||||
| Reclassification of distributions from capital, increase (decrease) | $ 17,854,000 | $ 16,339,000 | |||||||||
| Return of capital | [1] | $ 10,170,000 | |||||||||
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