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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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Exercise price per share or per unit of warrants or rights outstanding.

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-Publisher FASB
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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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