Investments - Gross Unrealized Gains and Losses and Cost of Equity (Detail) - USD ($) $ in Thousands |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Schedule Of Trading Securities And Other Trading Assets [Line Items] | ||
| Equity securities, Cost | $ 31,164 | $ 31,165 |
| Equity securities, Gross Unrealized Gains | 24,676 | 26,328 |
| Equity securities, at fair value | 55,840 | 57,493 |
| Domestic Common Stock [Member] | ||
| Schedule Of Trading Securities And Other Trading Assets [Line Items] | ||
| Equity securities, Cost | 31,164 | 31,165 |
| Equity securities, Gross Unrealized Gains | 24,676 | 26,328 |
| Equity securities, at fair value | $ 55,840 | $ 57,493 |