Income Taxes - Summary of Changes in Valuation Allowance (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
---|---|---|---|
Sep. 30, 2023 |
Sep. 30, 2022 |
Sep. 30, 2021 |
|
Valuation Allowance [Line Items] | |||
Balance at beginning of period | $ 5,973,000 | $ 5,853,000 | $ 5,518,000 |
Valuation allowance, deferred tax asset, increase (decrease), amount | 121,000 | 27,000 | |
Balance at end of period | 6,378,000 | 5,973,000 | 5,853,000 |
Allowance provision for new operating and other loss carryforwards | |||
Valuation Allowance [Line Items] | |||
Valuation allowance, deferred tax asset, increase (decrease), amount | 573,000 | 325,000 | 505,000 |
Allowance benefits | |||
Valuation Allowance [Line Items] | |||
Valuation allowance, deferred tax asset, increase (decrease), amount | $ (168,000) | $ (205,000) | $ (170,000) |