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Income Taxes - Additional Information (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | Sep. 30, 2020
Income Taxes [Line Items] |  |  |  |  |
Effective tax rate (ETR) from continuing operations | 26.30% | 30.70% | 25.50% | 28.30% |
Federal statutory rate |  |  | 21.00% |  |
State net operating loss carryforwards |  |  |  |  | $ 0.7
Domestic Tax Authority [Member] | 2027-2038 [Member] |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |
Net operating loss carryforwards |  |  |  |  | 512.6
State and Local Jurisdiction [Member] | 2021-2040 [Member] |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |
Net operating loss carryforwards |  |  |  |  | $ 223.9
Minimum [Member] | Domestic Tax Authority [Member] |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |
Operating loss carryforwards, expiration year |  |  |  |  | 2027
Minimum [Member] | State and Local Jurisdiction [Member] |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |
Operating loss carryforwards, expiration year |  |  |  |  | 2021
Maximum [Member] | Domestic Tax Authority [Member] |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |
Operating loss carryforwards, expiration year |  |  |  |  | 2038
Maximum [Member] | State and Local Jurisdiction [Member] |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |
Operating loss carryforwards, expiration year |  |  |  |  | 2040

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