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v3.20.4

Subsequent Events - Additional Information (Detail) |  |  |  | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Nov. 12, 2020 USD ($) Air-craft | Nov. 04, 2020 USD ($) | Oct. 30, 2020 USD ($) $ / shares shares | Sep. 30, 2019 USD ($) | Nov. 14, 2020 USD ($) | Nov. 13, 2020 USD ($) | Sep. 30, 2020 $ / shares | Jun. 28, 2018 shares
Subsequent Event [Line Items] |  |  |  |  |  |  |  |
Warrants to purchase shares of common stock | shares |  |  |  |  |  |  |  | 250,000
Warrants of common stock exercise price | $ / shares |  |  |  |  |  |  | $ 0.004 |
Prepayment |  |  |  | $ 1,672,000 |  |  |  |
Subsequent Event [Member] | United [Member] | United Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |
Prepayment |  | $ 85,000,000.0 |  |  |  |  |  |
Subsequent Event [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |
Calculated collateral coverage ratio |  |  | 1.6 |  |  |  |  |
Subsequent Event [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |
Additional collateral coverage ratio |  |  | 1.6 |  |  |  |  |
Subsequent Event [Member] | Loan Agreement [Member] |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |
Warrants to purchase shares of common stock | shares |  |  | 4,899,497 |  |  |  |  |
Warrants of common stock exercise price | $ / shares |  |  | $ 3.98 |  |  |  |  |
Repayments of long term debt | $ 164,100,000 |  |  |  |  |  |  |
Number of aircraft financed | Air-craft | 44 |  |  |  |  |  |  |
Cash proceeds to fund debt pay down | $ 81,300 |  |  |  |  |  |  |
Subsequent Event [Member] | Loan Agreement [Member] | Cash in Hand [Member] |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |
Cash proceeds to fund debt pay down | $ 82,800 |  |  |  |  |  |  |
Subsequent Event [Member] | United Capacity Purchase Agreement [Member] | American Airlines Inc. [Member] |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |
Number of aircraft financed | Air-craft | 40 |  |  |  |  |  |  |
Subsequent Event [Member] | Secured Term Loan Facility [Member] | Loan Agreement [Member] |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |
Secured term loan facility, maximum borrowing capacity |  |  | $ 200,000,000.0 |  |  |  |  |
Secured term loan facility, amount borrowed |  |  | $ 43,000,000.0 |  |  |  |  |
Secured term loan facility, additional amount borrowed |  |  |  |  | $ 0 | $ 152,000,000.0 |  |
Long term debt, basis spread on variable rate |  |  | 3.50% |  |  |  |  |
Long term debt interest rate description |  |  | annual rate based on Adjusted LIBO (as defined in the Loan Agreement) plus 3.5% |  |  |  |  |

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