Summary of Significant Accounting Policies - Anti-dilutive Securities Excluded from the Computation of Diluted Net Loss (Detail) - shares shares in Thousands |
9 Months Ended | |
|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Employee Stock Option | ||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
| Antidilutive securities excluded from computation of earnings per share, amount | 6,667 | 5,953 |
| Unvested rTSRUs [Member] | ||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
| Antidilutive securities excluded from computation of earnings per share, amount | 104 | 93 |
| Unvested PSUs [Member] | ||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
| Antidilutive securities excluded from computation of earnings per share, amount | 104 | 93 |
| Unvested Restricted Stock [Member] | ||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
| Antidilutive securities excluded from computation of earnings per share, amount | 420 | 414 |