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Organization and Operations - Additional Information (Detail) |  |  |  |  |  | 1 Months Ended | 2 Months Ended | 9 Months Ended
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Mar. 04, 2021 Air-craft | Nov. 19, 2020 Air-craft | Nov. 04, 2020 Air-craft | Dec. 20, 2019 Air-craft | Nov. 26, 2019 Air-craft Airfleet | Jun. 30, 2021 Daily_Departure State Air-craft | Jun. 02, 2021 Air-craft | Aug. 17, 2021 Air-craft | May 05, 2021 Air-craft | Mar. 03, 2021 Air-craft | Jun. 30, 2021 Daily_Departure State Air-craft City Employee
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of states in which entity operates | State |  |  |  |  |  | 36 |  |  |  |  | 36
Number of aircrafts operated |  |  |  |  |  |  |  |  |  |  | 155
Number of cities in which entity operates | City |  |  |  |  |  |  |  |  |  |  | 116
Number of daily departures | Daily_Departure |  |  |  |  |  | 470 |  |  |  |  | 470
Number of employees | Employee |  |  |  |  |  |  |  |  |  |  | 3,191
Aircraft leases to third party |  |  |  |  |  |  |  |  |  |  | 12
American Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Amendment Term |  | 5 years |  |  |  |  |  |  |  |  |
Maximum number of aircraft withdraw in twenty twenty one |  | 10 |  |  |  |  |  |  |  |  |
Maximum number of aircraft withdraw in twenty twenty two |  | 5 |  |  |  |  |  |  |  |  |
Maximum number of aircraft withdraw in twenty twenty three |  | 5 |  |  |  |  |  |  |  |  |
Aircrafts able to be withdrawn in future under normal withdrawal rights |  | 20 |  |  |  |  |  |  |  |  |
Aircrafts able to be withdrawn in future, thereafter under normal withdrawal rights |  | 20 |  |  |  |  |  |  |  |  |
American Capacity Purchase Agreement [Member] | CRJ-900 Aircraft [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts operated |  | 40 |  |  |  |  |  |  |  |  | 45
Amended and Restated American Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts withdrawable on conditions |  |  |  |  |  | 1 |  |  |  |  | 1
Amended and Restated American Capacity Purchase Agreement [Member] | CRJ-900 Aircraft [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts expected to operate | 5 |  |  |  |  |  |  |  |  | 3 |
American Capacity Purchase Agreement (Amendment No. 2) [Member] | CRJ-900 Aircraft [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts expected to operate |  |  |  |  |  |  | 3 |  | 5 |  |
American Capacity Purchase Agreement (Amendment No. 2) [Member] | CRJ-900 Aircraft [Member] | Forecast |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts expected to operate |  |  |  |  |  |  |  | 5 |  |  |
United Capacity Purchase Agreement [Member] | E-175 Aircraft [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts operated |  |  |  |  |  |  |  |  |  |  | 60
United Capacity Purchase Agreement [Member] | E-175 Aircraft [Member] | United [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts operated |  |  |  |  |  |  |  |  |  |  | 42
Aircraft lease extension period |  |  |  |  | 5 years |  |  |  |  |  |
Number of aircraft leased |  |  |  |  | 42 |  |  |  |  |  |
Lease expiration year |  |  |  |  | 2028 |  |  |  |  |  |
Number of aircrafts owned | Airfleet |  |  |  |  | 18 |  |  |  |  |  |
Notice period for termination of agreement |  |  |  |  |  |  |  |  |  |  | Permits United, subject to certain conditions, including the payment of certain costs tied to aircraft type, to terminate the agreement in its discretion, or remove E-175 aircraft from service, by giving us notice of 90 days or more
United Capacity Purchase Agreement [Member] | E-175 Aircraft [Member] | United [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Lease expiration year |  |  |  |  | 2024 |  |  |  |  |  |
United Capacity Purchase Agreement [Member] | E-175 Aircraft [Member] | United [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Lease expiration year |  |  |  |  | 2028 |  |  |  |  |  |
United Capacity Purchase Agreement [Member] | E175LL Aircraft [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts operated |  |  |  |  |  |  |  |  |  |  | 20
Number of additional aircrafts |  |  |  |  | 20 |  |  |  |  |  |
Number of years in operation |  |  |  |  | 12 years |  |  |  |  |  |
Air crafts expiring month and year description |  |  |  |  |  |  |  |  |  |  | expiring between November 2032 and June 2033
Number of aircraft leased |  |  | 20 |  |  |  |  |  |  |  |
Aircraft lease term |  |  | 12 years |  |  |  |  |  |  |  |
Number of aircraft delivered |  |  |  |  |  | 20 |  |  |  |  |
United Capacity Purchase Agreement [Member] | E175LL Aircraft [Member] | United [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Notice period for termination of agreement |  |  |  |  |  |  |  |  |  |  | Commencing five (5) years after the actual in-service date, United has the right to remove the E-175 aircraft from service by giving us notice of 90 days or more, subject to certain conditions, including the payment of certain wind-down expenses plus, if removed prior to the ten (10) year anniversary of the in-service date, certain accelerated margin payments
United Capacity Purchase Agreement [Member] | CRJ-700 Aircraft [Member] | United [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Aircraft lease term |  |  |  |  | 9 years |  |  |  |  |  |
DHL Flight Services Agreement [Member] | Boeing 737400F [Member] |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts operated |  |  |  | 2 |  |  |  |  |  |  |
Number of aircraft leased |  |  |  | 2 |  |  |  |  |  |  |
Aircraft lease term |  |  |  | 5 years |  |  |  |  |  |  |
Notice period for termination of agreement |  |  |  |  |  |  |  |  |  |  | At any time after the first anniversary of the commencement date of the first aircraft placed in service with 90 day’s written notice
Aircraft option to extend agreement description |  |  |  |  |  |  |  |  |  |  | DHL has the option to extend the agreement with respect to one or more aircraft for a period of one year with 90 days’ advance written notice.

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