Long-Term Debt and Other Borrowings - Schedule of Long-term Debt (Parenthetical) (Detail)			1 Months Ended						12 Months Ended
	Jun. 28, 2018 USD ($) Air-craft	Jun. 27, 2018 USD ($) Air-craft	Sep. 27, 2019 USD ($)	Jun. 30, 2019 USD ($) Airfleet	Jan. 31, 2019 USD ($)	Jun. 30, 2018 USD ($) Air-craft	Feb. 28, 2018 Engine	Dec. 31, 2017 USD ($) Air-craft	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($) Air-craft	Sep. 30, 2015 USD ($) Air-craft	Sep. 30, 2007 USD ($) Airfleet	Sep. 30, 2005 USD ($) Airfleet	Sep. 30, 2004 USD ($) Airfleet	Sep. 30, 2014 USD ($) Airfleet
Debt Instrument [Line Items]
Imputed interest							9.128%
Number of spare engines leased \| Engine							2
CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 69,600,000	$ 27,500,000
Long term debt interest rate description	LIBOR plus a spread ranging from 3.50% for the senior promissory notes to 7.50% for the subordinated promissory notes								LIBOR plus 3.50%.
Long term debt basis spread on variable rate		3.50%
Number of aircraft financed \| Air-craft	6	6
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2019 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2019	2019
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2019 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Number of aircraft refinanced \| Airfleet														5	9
Debt instrument, face amount														$ 118,000,000
Long term debt interest rate description									London InterBank Offered Rate ("LIBOR"), plus 3%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2019 [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate														3.00%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2019 [Member] \| CRJ-700 [Member]
Debt Instrument [Line Items]
Number of aircraft refinanced \| Airfleet															5
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2019 [Member] \| Five C- R- J-700 and Nine C- R- J-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount															$ 254,700,000
Long term debt interest rate description									monthly LIBOR plus 3%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2019 [Member] \| Five C- R- J-700 and Nine C- R- J-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate															3.00%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2022	2022
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Number of aircraft refinanced \| Airfleet													3
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| CRJ-700 [Member]
Debt Instrument [Line Items]
Number of aircraft refinanced \| Airfleet													3
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Three C- R- J-900 and Three C- R- J-700 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount													$ 120,300,000
Long term debt interest rate description									monthly LIBOR plus 2.25%
Long term debt interest rate percentage									4.27%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Three C- R- J-900 and Three C- R- J-700 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate													2.25%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Ten C- R- J-900 Aircraft [Member]
Debt Instrument [Line Items]
Debt instrument, face amount																$ 88,400,000
Long term debt interest rate description									LIBOR plus a spread ranging from 1.95% to 7.25%
Number of aircraft financed \| Airfleet																10
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Ten C- R- J-900 Aircraft [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage									3.97%							1.95%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Ten C- R- J-900 Aircraft [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage									9.27%							7.25%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2024 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2024	2024
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2024 [Member] \| Eight C- R- J-900 Aircraft [Member]
Debt Instrument [Line Items]
Debt instrument, face amount																$ 114,500,000
Number of aircraft financed \| Airfleet																8
Long term debt interest rate percentage																5.00%
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2027 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2027	2027
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2027 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount												$ 170,200,000
Number of aircraft financed \| Air-craft												7
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2028	2028
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] \| Ten E-175 Aircraft [Member]
Debt Instrument [Line Items]
Debt instrument, face amount											$ 246,000,000
Number of aircraft financed \| Air-craft											10
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] \| Ten E-175 Aircraft [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage									4.75%
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] \| Ten E-175 Aircraft [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage									6.25%
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2028	2028
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] \| Eight E-175 Aircraft [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Number of aircraft refinanced \| Air-craft											8
Debt instrument, face amount											$ 195,300,000
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2022	2022
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2022	2022
Number of aircraft refinanced \| Air-craft						6		9
Debt instrument, face amount						$ 27,500,000		$ 74,900,000
Number of aircraft financed \| Air-craft						9
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| CRJ-900 [Member] \| Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 69,600,000
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2022	2022
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2022 [Member] \| Flight Equipment [Member]
Debt Instrument [Line Items]
Debt instrument, face amount										$ 99,100,000
Long term debt interest rate description									monthly LIBOR plus 7.25%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2022 [Member] \| Flight Equipment [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate										7.25%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2020 [Member] \| Flight Equipment [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2020	2020
Debt instrument, face amount												$ 8,300,000
Long term debt interest rate percentage												5.163%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2020 [Member] \| Flight Equipment Maintenance [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2020	2020
Debt instrument, face amount										$ 11,900,000	$ 11,900,000
Long term debt interest rate description									Three-month LIBOR plus a spread ranging from 2.93% to 2.96%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2020 [Member] \| Flight Equipment Maintenance [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage									5.02%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2020 [Member] \| Flight Equipment Maintenance [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage									5.05%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2020 [Member] \| Flight Equipment Maintenance [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate										2.93%	2.93%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2020 [Member] \| Flight Equipment Maintenance [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate										2.96%	2.96%
Notes Payable to Financial Institution Due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2020	2020
Notes Payable to Financial Institution Due 2020 [Member] \| Flight Equipment Maintenance [Member]
Debt Instrument [Line Items]
Debt instrument, face amount											$ 10,200,000	$ 10,200,000
Long term debt interest rate description									three-month LIBOR plus 3.07%
Long term debt interest rate percentage									5.16%
Notes Payable to Financial Institution Due 2020 [Member] \| Flight Equipment Maintenance [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage											3.07%	3.07%
Notes Payable to Financial Institution Due 2019 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2019	2019
Notes Payable to Financial Institution Due 2019 [Member] \| Flight Equipment Maintenance [Member]
Debt Instrument [Line Items]
Debt instrument, face amount										$ 25,000,000
Long term debt interest rate description									Three-month LIBOR plus 3.30%
Long term debt basis spread on variable rate										3.30%
Other Obligations Due to Financial Institution, Collateralized by the Underlying Equipment, Due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2023	2023
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2024	2024
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member] \| Flight Equipment [Member]
Debt Instrument [Line Items]
Debt instrument, face amount					$ 91,200,000
Long term debt interest rate description									monthly LIBOR plus 3.10%
Long term debt interest rate percentage									5.12%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member] \| Flight Equipment [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate					3.10%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2023	2023
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] \| CRJ-700 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount				$ 70,000,000
Long term debt interest rate description									monthly LIBOR plus 5.25%
Long term debt interest rate percentage									7.27%
Number of aircraft financed \| Airfleet				10
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] \| CRJ-700 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate				5.25%
Notes Payable to Financial Institution Due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year									2023	2023
Debt instrument, face amount			$ 8,000,000						$ 8,000
Long term debt interest rate description									monthly LIBOR plus 5.25%
Long term debt basis spread on variable rate			5.25%
Long term debt interest rate percentage									7.27%
Senior Notes Due Two Thousand Twenty Seven [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount												$ 151,000,000
Long term debt interest rate description									monthly LIBOR plus 2.71%
Long term debt interest rate percentage									4.73%
Senior Notes Due Two Thousand Twenty Seven [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate												2.71%
Subordinated Notes Due Two Thousand Twenty Seven [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Imputed interest												6.25%
Debt discount												$ 8,100,000
Senior Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member]
Debt Instrument [Line Items]
Long term debt interest rate description									Three-month LIBOR plus a spread ranging from 2.20% to 2.32%
Senior Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, face amount											$ 172,000,000
Long term debt interest rate percentage									4.29%
Senior Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage									4.41%
Senior Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate											2.20%
Senior Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate											2.32%
Subordinated Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage									4.50%
Senior Notes due Two Thousand Twenty Two [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount								$ 46,900,000
Long term debt interest rate description									three-month LIBOR plus 3.50
Long term debt interest rate percentage									5.59%
Senior Notes due Two Thousand Twenty Two [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate								3.50%
Subordinated Notes DueTwoThousandTwentyTwo [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Long term debt interest rate description									three-month LIBOR plus 4.50%
Long term debt interest rate percentage									6.59%
Subordinated Notes DueTwoThousandTwentyTwo [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage								4.50%
Senior Notes Due 2020 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 65,800,000
Long term debt basis spread on variable rate	3.50%					3.50%
Long term debt interest rate percentage										5.59%
Senior Notes Due 2020 [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt interest rate description										Three-month LIBOR plus 3.50%
Subordinated Notes Due 2020 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 29,800,000
Long term debt basis spread on variable rate	7.50%					7.50%
Long term debt interest rate percentage										9.59%
Subordinated Notes Due 2020 [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt interest rate description										three-month LIBOR plus 7.50%