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Selected Quarterly Financial Data (unaudited) - Narrative (Details) - USD ($) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2021 | Jun. 30, 2021 | Mar. 31, 2021 | Dec. 31, 2020 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |
Proceeds from federal relief grants |  |  |  |  |  | $ 4,299,000 | $ 4,629,000 | $ 15,597,000
Proceeds for reimbursement of legal fees |  | $ 658,000,000 |  |  |  |  |  |
Discontinued Operations, Held-for-sale |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |
Gain on sale of assets |  | 30,288,000,000 |  |  | $ 27,470,000,000 |  |  |
Grove Management Services |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |
Operating Revenue | $ 3,083,000,000 | 5,114,000,000 | $ 4,685,000,000 | $ 2,869,000,000 | 3,246,000,000 |  |  |
Operating expenses | $ 3,015,000,000 | $ 4,545,000,000 | $ 4,150,000,000 | $ 2,631,000,000 | $ 2,951,000,000 |  |  |

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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