Investments - Schedule of Company's Investments in Limited Partnerships (Detail) - USD ($) $ in Thousands |
6 Months Ended | 12 Months Ended | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Jun. 30, 2026 |
Dec. 31, 2025 |
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| Investment Securities [Line Items] | ||||||||||||||||||||||
| Carrying Value | $ 16,394 | $ 17,690 | ||||||||||||||||||||
| Unfunded balance | 3,791 | 3,652 | ||||||||||||||||||||
| Private US Lower Middle Market Companies [Member] | ||||||||||||||||||||||
| Investment Securities [Line Items] | ||||||||||||||||||||||
| Carrying Value | [1],[2],[3] | 1,668 | 1,877 | |||||||||||||||||||
| Unfunded balance | [1],[2],[3] | $ 0 | $ 0 | |||||||||||||||||||
| Percentage investment held by the entity | [1],[2],[3] | 12.22% | 12.31% | |||||||||||||||||||
| Bank Loans Public and Private Corporate Bonds Asset Backed Securities Equity and Debt Restructuring [Member] | ||||||||||||||||||||||
| Investment Securities [Line Items] | ||||||||||||||||||||||
| Carrying Value | [1],[2],[4] | $ 573 | $ 587 | |||||||||||||||||||
| Unfunded balance | [1],[2],[4] | $ 0 | $ 0 | |||||||||||||||||||
| Percentage investment held by the entity | [1],[2],[4] | 1.30% | 1.27% | |||||||||||||||||||
| Power Utility and Energy Industries and Infrastructure [Member] | ||||||||||||||||||||||
| Investment Securities [Line Items] | ||||||||||||||||||||||
| Carrying Value | [2],[5],[6] | $ 2,854 | $ 2,769 | |||||||||||||||||||
| Unfunded balance | [2],[5],[6] | $ 0 | $ 0 | |||||||||||||||||||
| Percentage investment held by the entity | [2],[5],[6] | 0.18% | 0.18% | |||||||||||||||||||
| Senior and Junior Debts of Private Equity-Backed Companies [Member] | ||||||||||||||||||||||
| Investment Securities [Line Items] | ||||||||||||||||||||||
| Carrying Value | [2],[7],[8] | $ 1,198 | $ 1,333 | |||||||||||||||||||
| Unfunded balance | [2],[7],[8] | $ 0 | $ 0 | |||||||||||||||||||
| Percentage investment held by the entity | [2],[7],[8] | 0.53% | 0.53% | |||||||||||||||||||
| Mature Real Estate Private Equity Funds And Portfolios Globally [Member] | ||||||||||||||||||||||
| Investment Securities [Line Items] | ||||||||||||||||||||||
| Carrying Value | [2],[9] | $ 5,531 | $ 6,182 | |||||||||||||||||||
| Unfunded balance | [2],[9] | $ 1,706 | $ 2,042 | |||||||||||||||||||
| Percentage investment held by the entity | [2],[9] | 1.32% | 1.32% | |||||||||||||||||||
| Credit and Equity Investments, Primarily in Private Equity-Owned Companies [Member] | ||||||||||||||||||||||
| Investment Securities [Line Items] | ||||||||||||||||||||||
| Carrying Value | [2],[10] | $ 4,570 | $ 4,942 | |||||||||||||||||||
| Unfunded balance | [2],[10] | $ 2,085 | $ 1,610 | |||||||||||||||||||
| Percentage investment held by the entity | [2],[10] | 0.53% | 0.54% | |||||||||||||||||||
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