Long-Term Debt, Finance Leases, and Other Borrowings - Additional Information (Detail)					3 Months Ended	6 Months Ended	9 Months Ended
	Jan. 11, 2024 USD ($)	Sep. 06, 2023 USD ($)	Dec. 27, 2022 USD ($)	Oct. 30, 2020 USD ($) $ / shares shares	Mar. 31, 2024 USD ($) $ / shares	Mar. 31, 2024 USD ($) $ / shares	Jun. 30, 2023 USD ($)	Jun. 14, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Property and equipment-gross					$ 792,193,000	$ 792,193,000			$ 1,049,203,000
Long-Term Debt					393,413,000	393,413,000			$ 528,278,000
Gain on investments					$ 7,230,000	$ 7,230,000
Warrants of common stock exercise price | $ / shares					$ 3.98	$ 3.98
Treasury Loan [Member] | Maximum [Member]
Debt Instrument [Line Items]
Calculated collateral coverage ratio				1.55
Treasury Loan [Member] | Minimum [Member]
Debt Instrument [Line Items]
Additional collateral coverage ratio				1.55
Loan Agreement [Member]
Debt Instrument [Line Items]
Warrants to purchase shares of common stock | shares				4,899,497
Warrants of common stock exercise price | $ / shares				$ 3.98
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Repayments of long term debt	$ 2,100,000
Permitted amount to redraw from existing credit facility		$ 7,900,000
Revolving Credit Facility [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Line of credit available to draw								$ 2,200,000
Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Revolving commitments		50,700,000
Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Revolving commitments		$ 30,700,000
United [Member]
Debt Instrument [Line Items]
Repayments of long term debt	10,500,000
United Capacity Purchase Agreement [Member]
Debt Instrument [Line Items]
Repayments of long term debt	10,500,000
Gain on investments	$ 7,200,000
United Capacity Purchase Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate		3.50%	3.50%
Revolving loan			$ 10,500,000
Covenant capping restricted payments			5,000,000
Repayments of lines of credit					$ 10,500,000
Revolving commitments			$ 30,700,000
Rental coverage ratio			1
United Capacity Purchase Agreement [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Amount required							$ 15,000,000
United Capacity Purchase Agreement [Member] | Revolving Credit Facility [Member] | SOFR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate		4.50%	4.50%
United Capacity Purchase Agreement [Member] | United [Member]
Debt Instrument [Line Items]
Percentage of controllable completion factor						99.30%
United Capacity Purchase Agreement [Member] | United [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Deemed prepayment, outstanding					4,500,000	$ 4,500,000
Amount funded by company							$ 25,500,000
Additional prepayment with potential forgiveness					15,000,000	15,000,000
Equipment Notes [Member]
Debt Instrument [Line Items]
Long-Term Debt					97,300,000	$ 97,300,000
Secured Term Loan Facility [Member] | Loan Agreement [Member]
Debt Instrument [Line Items]
Secured term loan facility, maximum borrowing capacity				$ 200,000,000.0
Debt instrument, maturity date						Oct. 30, 2025
Secured Term Loan Facility [Member] | Loan Agreement [Member] | Treasury Loan [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate				3.50%
Secured term loan facility, amount borrowed										$ 195,000,000.0
Secured term loan facility, additional amount borrowed					0	$ 0
Debt instrument, maturity date				Oct. 30, 2025
Aircraft and Equipment [Member] | Pledged as Collateral [Member]
Debt Instrument [Line Items]
Property and equipment-gross					$ 528,000,000	$ 528,000,000