Fair Value Measurements - Additional Information (Detail) - USD ($) |
12 Months Ended | |
|---|---|---|
Sep. 30, 2022 |
Sep. 30, 2021 |
|
| Transfer from fair value level 1 to level 2 | $ 0 | $ 0 |
| Transfer from fair value level 2 to level 1 | 0 | 0 |
| Transfer into (out of) level 3 | 0 | $ 0 |
| 2026 Notes [Member] | Notes Payable [Member] | Level 1 [Member] | ||
| Notes Payable, Fair Value Disclosure | $ 37,300,000 | |