Inventories - Narrative (Details) - USD ($)  | 
9 Months Ended | 12 Months Ended | 
|---|---|---|
Jun. 30, 2020  | 
Sep. 30, 2019  | 
|
| Inventory Disclosure [Abstract] | ||
| Proceeds received from insurance relating to property and casualty damage claims | $ 486,000 | |
| Proceeds from federal relief grants | $ 4,629,000 | $ 15,597,000 | 
| X | ||||||||||
- Definition Proceeds From Federal Relief Grants No definition available. 
  | 
| X | ||||||||||
- Definition Proceeds Received from Insurance Relating to Property and Casualty Damage Claims No definition available. 
  | 
| X | ||||||||||
- References No definition available. 
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