| Long-Term Debt - Summary of Maximum Senior Leverage Ratio Required to Maintain for Vintage Stock (Details) | 3 Months Ended | 12 Months Ended | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jun. 30, 2021 | Mar. 31, 2021 | Dec. 31, 2020 | Sep. 30, 2020 | Jun. 30, 2020 | Mar. 31, 2020 | Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Mar. 31, 2019 | Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | |
| Debt Instrument [Line Items] | |||||||||||||||
| Senior leverage ratio | 200.00% | ||||||||||||||
| Maximum | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Senior leverage ratio | 240.00% | 240.00% | 260.00% | 265.00% | 285.00% | 285.00% | 200.00% | ||||||||
| Maximum | Scenario Forecast | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Senior leverage ratio | 155.00% | 160.00% | 185.00% | 205.00% | 215.00% | 220.00% | 240.00% | ||||||||
| Minimum | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Senior leverage ratio | 200.00% | ||||||||||||||
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- Definition Senior leverage ratio. No definition available. 
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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. No definition available. 
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